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1.	Jonsson, Rasmus, 1989, et al. (author) Chemical poisoning by zinc and phosphorous of Pt/Ba/Al2O3 NOx storage catalysts 2019 In: Applied Catalysis A: General. - : Elsevier BV. - 1873-3875 .- 0926-860X. ; 571, s. 158-169 Journal article (peer-reviewed)abstract The effects of phosphorous and zinc on the performance of Pt/Ba/Al2O3 catalysts were investigated through wet impregnation of ammonium phosphate and zinc acetate aqueous solutions. Six different sample combinations were studied; 1 wt-% P, 1 wt-% Zn, 1 wt-% P with 1 wt-% Zn, 2 wt-% P, 2 wt-% Zn, 2 wt-% P with 2 wt-% Zn. NOx storage and reduction (NSR) activity and NO2 temperature programmed desorption (TPD) profiles were measured before and after impregnation of P and Zn. Samples containing P performed significantly worse than samples only containing Zn in both NSR activity and TPD measurements. The increased NOx slip during lean phase in activity measurements for P-poisoned samples is mainly related to an increased slip of NO2. This was found for both NO and NO2 in the gas feed during lean phase and suggests that it is mainly the storage component that is poisoned and not the noble metal. Furthermore, the combination (1 wt-% P and 1 wt-% Zn) proved to result in slightly worse performance than only 1 wt-% P, however this was not the case for samples containing 2 wt-%, where the addition of zinc reduced the negative effect of phosphorous. Measurements from NO2-TPD experiments showed that NOx release at low temperature was not affected by the addition of P, while desorption in the temperature range 425–475 °C was significantly reduced. It can therefore be concluded that the poisoning mainly is related to barium NOx storage sites and not to alumina sites. Moreover, X-ray diffraction measurements indicate that some of the barium species are affected by phosphorous. Images from scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX) mapping were in line with the results seen in both the activity tests and NO2-TPD experiments. Phosphorous was concentrated at the same position as barium in the observed images, whereas zinc was more evenly distributed over the surface. For the sample with both 2 wt-% P and 2 wt-% Zn, X-ray photoelectron spectroscopy measurements indicate that Zn and P have a low interaction and this suggests that most of the zinc and phosphorous are separated. However, STEM-EDX showed agglomerates of some zinc and phosphorous, which could be zinc phosphates. This is a plausible explanation of the decreased deactivation observed after introducing 2 wt-% Zn compared to the sample only containing 2 wt-% P.
2.	Jonsson, Rasmus, 1989, et al. (author) Gas-phase phosphorous poisoning of a Pt/Ba/Al2O3 NOx storage catalyst 2018 In: Catalysts. - : MDPI AG. - 2073-4344. ; 8:4 Journal article (peer-reviewed)abstract The effect of phosphorous exposure on the NO x storage capacity of a Pt/Ba/Al 2 O 3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H 2 O and O 2 . The NOx storage capacity was measured before and after the phosphorus exposure and a significant loss of the NO x storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N 2 -physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P 4 O 10 . However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO 3 – ). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sample
3.	Andonova, Stanislava, 1977, et al. (author) Micro-calorimetric studies of NO2 adsorption on Pt/BaO-supported on gamma-Al2O3 NOx storage and reduction (NSR) catalysts-Impact of CO2 2017 In: Molecular Catalysis. - : Elsevier BV. - 2468-8231. ; 436, s. 43-52 Journal article (peer-reviewed)abstract The adsorption of NO2 on Pt/BaO/gamma Al2O3 catalyst has been investigated by micro calorimetry at atmospheric pressure, NOx storage tests and temperature-programmed desorption (TPD). The heat of adsorption of NO2 (Delta H-ads(NO2)) was determined over a wide range of NOx coverages, as the catalyst was exposed to 500/900 ppm NO2 in the absence/presence of 5% CO2 in the range of 423-773 K. The temperature dependent changes of Delta H-ads(NO2) verified the presence of energetically different NOx storage sites with different binding strength. The Delta H-ads(NO2) was found to follow a linear correlation versus temperature, ranging for example from -134.5 to -178.8 kJ/mol for NOx storage over Pt/BaO/gamma Al2O3 at 423-673 K. Thus, at high temperature mostly strongly bound nitrates were formed, while at lower temperature more loosely bound species were also present. Interestingly, the heat of adsorption was higher when using higher NO2 concentration, indicating more bulk barium nitrate formation. This is consistent with the TPD data where a clear high temperature peak was visible after adsorption using 900 ppm NO2 at 423 and 473 K, which was not the case for 500 ppm NO2. Moreover, the micro-calorimetric data also provided evidence in support of the detrimental effect of CO2 on the NOx uptake process. The heat released during the NOx storage in 500 ppm NO2 + 5% CO2 was determined to be significantly reduced ca. -97.8 kJ mol(-1) at 423 K, but ca. -134.5 kJ mol(-1) without CO2. Furthermore, our results show that it is critical to measure heat of adsorption for surface compounds since they are significantly different compared to thermodynamic data for bulk materials.
4.	Andonova, Stanislava, 1977, et al. (author) The effect of iron loading and hydrothermal aging on one-pot synthesized Fe/SAPO-34 for ammonia SCR 2016 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 180, s. 775-787 Journal article (peer-reviewed)abstract The current commercially-available technique for NOx reduction for diesel engines is the selective catalytic reduction (SCR) of NOx with NH3 over Cu zeolites. One of the problems of this technique is their limited ability to convert NOx at diesel particulate filter (DPF) regeneration temperatures. In addition, during regeneration of the DPF there is a risk of thermally deactivating the SCR catalyst. Thus, the aim of the current work was the development of a catalytic system that can reduce NOx both at low as well as high temperature and in addition is stable at high temperature. In order to reach this goal, a Fe/SAPO-34 with chabazite (CHA) structure was combined in a system with a commercial Cu/CHA catalyst. Earlier studies have shown that it is difficult to ion-exchange Fe into CHA structures due to steric hindrance, and we have therefore used a novel synthesis procedure which incorporated iron directly into the zeolite structure. Fe/SAPO-34 with three different Fe-loadings (0.27; 0.47 and 1.03 wt.% Fe) were synthesized and the catalysts were characterized using inductively coupled plasma atomic spectroscopy (ICP-AES), N-2 adsorption-desorption isotherms, BET area measurements and X-ray diffraction (XRD). The chemical composition, porous and crystalline structure of the parent SAPO-34 sample were found to be only slightly affected by addition of small amounts of Fe in the framework zeolite structure. However, more visible changes in the crystallinity were observed in the Fe/SAPO-34 catalysts with higher Fe content, which were attributed to the unit cell size expansion provoked by integration of higher amounts of Fe into the zeolite SAPO-34 framework. The Fe/SAPO-34 with the lowest Fe-loading (0.27 wt.%) was found to be the best catalyst when considering activity as well as high temperature stability. The synthesized Fe/SAPO-34 catalyst demonstrated a significantly improved NOx reduction performance at high temperatures (600-750 degrees C) when compared to a commercial Cu/CHA SCR system, and the combined system (Fe/SAPO-34+ Cu/CHA) exhibited a very good performance in a large temperature interval (200-800 degrees C) that encompasses most diesel exhaust gas conditions.
5.	Arora, Prakhar, 1987, et al. (author) Investigating the effect of Fe as a poison for catalytic HDO over sulfided NiMo alumina catalysts 2018 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 227, s. 240-251 Journal article (peer-reviewed)abstract The effect of iron (Fe) as poison present in renewable feeds was studied during hydrodeoxygenation (HDO) overmolybdenum based sulfided catalysts. The study was carried out at 6 MPa and 325 °C in batch reaction conditions. Different concentrations of Fe in the feed were tested over MoS2/Al2O3 and NiMoS/Al2O3. A notable drop in activity for the conversion of oxygenates was observed for both catalyst systems with an increased concentration of Fe in the feed. However, the changes in selectivity of products was opposite for unpromoted and Nipromoted catalysts. In the case of the NiMoS catalyst, at higher Fe concentration, the decarbonated product (C17 hydrocarbons) decreased while the direct hydrodeoxygenation product (C18 hydrocarbons)increased. On the contrary, for the base catalyst (MoS2), there was a decrease in the yield of direct hydrodeoxygenation (C18 hydrocarbons) products and an increase in yield of decarbonated products (C17 hydrocarbons). These sulfided catalysts have different sites for these two different reaction routes and they interacted differently with Fe during the deactivation process. With surface deposition of Fe, the ability of these catalysts to create active sites i.e. via sulfur vacancies deteriorated. TEM-EDX results suggested that the effect of Ni as a promoter for the decarbonation route was nullified and a resultant FeMo phase explains the drop in activity and change in selectivity.
6.	Arora, Prakhar, 1987, et al. (author) Kinetic study of hydrodeoxygenation of stearic acid as model compound for renewable oils 2019 In: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 364, s. 376-389 Journal article (peer-reviewed)abstract The kinetics during hydrodeoxygenation (HDO) of stearic acid (SA) was investigated to explore the fundamental chemistry and the reaction scheme involved for the reaction with a sulfide NiMo/Al2O3catalyst. Intermediates like octadecanal (C18 O) and octadecanol (C18 OH) were used to resolve the reaction scheme and explain the selectivity for the three major reaction routes (decarboxylation, decarbonylation and direct-HDO). Several reaction parameters, like temperature, pressure, feed concentration and batch-reactor stirring rate, were explored for their effect on changes in rate of conversion and selectivity. A weaker dependence on pressure (40–70 bar) and strong dependence on temperature (275–325 °C) was found for the product distribution during HDO of SA. A model based on Langmuir–Hinshelwood type kinetics was developed to correlate the experimental data. The model well predicted trends in variation of selectivities with the reaction conditions, in part by including intermediates like octadecanol and octadecanal and it predicted phenomenon like inhibiting effects of the fatty acid. The proposed kinetic model is expected to be applicable to liquid phase HDO of different renewable feeds containing long chain fatty acids, methyl esters and triglycerides etc.
7.	Auvray, Xavier, 1986, et al. (author) Aging of Cu/SSZ-13 for NH3 SCR in mixed lean condition 2018 Conference paper (other academic/artistic)abstract Two catalytic methods have been developed to remove the NOx emissions from diesel vehicles and comply with the emission regulations: the NOx storage and reduction process (NSR) and the reduction of NOx with NH3 (SCR). Advanced systems combining these two methods for an optimum efficiency are now studied. SCR catalysts are subjected alternating lean and rich conditions as well as to high temperatures in rich conditions during deSOx of the LNT material. The purpose of the present work is therefore to determine the response of a Cu/SSZ-13 to several aging treatments at 800°C involving rich and/or lean exposure. Deactivation was observed after all types of aging. However strong differences in deactivation degree exists between aging procedures. Lean aging, for 8h at 800°C, was the most moderate aging tested although it brought about significant activity loss below 250°C. Alternating between long lean periods and short rich periods caused slightly stronger deactivation, which was most significant at 200°C. However, the switching frequency between lean and rich had negligible influence on subsequent activity. As shown in Figure 1, SCR activity after 8h exposure in H2 was outstandingly low. It increased monotonically with temperature to reach a maximum of 58% NO conversion. Further investigation pertaining to the rich treatment was performed. The aging time was reduced to 2h and, for direct comparison, a 32h cycling aging was performed, implying a total rich time of 2h. Both samples were severely impacted over the whole temperature range. It revealed that 2h in rich conditions led to stronger deactivation than 8h in lean and lean/rich conditions, emphasizing the deterioration power of H2. Aging caused by rich conditions was so dominant that additional 30h in lean has negligible influence on SCR below 300°C. However, the long additional exposure to lean conditions lowered significantly the SCR activity between 400 and 500°C.
8.	Auvray, Xavier, 1986, et al. (author) Deactivation of Cu/SSZ-13 NH3-SCR catalyst by exposure to CO, H2, and C3H6 2019 In: Catalysts. - : MDPI AG. - 2073-4344. ; 9:11 Journal article (peer-reviewed)abstract Lean nitric oxide (NOx)-trap (LNT) and selective catalytic reduction (SCR) are efficient systems for the abatement of NOx. The combination of LNT and SCR catalysts improves overall NOx removal, but there is a risk that the SCR catalyst will be exposed to high temperatures and rich exhaust during the LNTs sulfur regeneration. Therefore, the effect of exposure to various rich conditions and temperatures on the subsequent SCR activity of a Cu-exchanged chabazite catalyst was studied. CO, H2, C3H6, and the combination of CO + H2 were used to simulate rich conditions. Aging was performed at 800 °C, 700 °C, and, in the case of CO, 600 °C, in a plug-flow reactor. Investigation of the nature of Cu sites was performed with NH3-temperature-programed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of probe molecules (NH3 and NO). The combination of CO and H2 was especially detrimental to SCR activity and to NH3 oxidation. Rich aging with low reductant concentrations resulted in a significantly larger deactivation compared to lean conditions. Aging in CO at 800 °C caused SCR deactivation but promoted high-temperature NH3 oxidation. Rich conditions greatly enhanced the loss of Brønsted and Lewis acid sites at 800 °C, indicating dealumination and Cu migration. However, at 700 °C, mainly Brønsted sites disappeared during aging. DRIFT spectroscopy analysis revealed that CO aging modified the Cu2+/CuOH+ ratio in favor of the monovalent CuOH+ species, as opposed to lean aging. To summarize, we propose that the reason for the increased deactivation observed for mild rich conditions is the transformation of the Cu species from Z2Cu to ZCuOH, possibly in combination with the formation of Cu clusters. © 2019, MDPI AG. All rights reserved.
9.	Auvray, Xavier, 1986, et al. (author) Kinetic modeling of NH3-SCR over a supported Cu zeolite catalyst using axial species distribution measurements 2015 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 163, s. 393-403 Journal article (peer-reviewed)abstract In this study, a kinetic model is developed for NH3-SCR over a honeycomb-monolith-supported Cu-zeolites using intra-catalyst axial species distribution measurements. An ammonia TPD experiment, together with micro calorimetry data were used for tuning the ammonia adsorption and desorption properties. The spatial distribution for NO oxidation, NH3 oxidation and NH3 "Standard" SCR were modeled between 200 and 400 degrees C. Four-step protocol measurements were employed in order to validate the transient functions of the model. The resulting kinetic model provides good spatiotemporal simulation of the SCR reaction and component reactions throughout the monolith catalyst system.
10.	Auvray, Xavier, 1986, et al. (author) Lean and rich aging of a Cu/SSZ-13 catalyst for combined lean NO x trap (LNT) and selective catalytic reduction (SCR) concept 2019 In: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 9:9, s. 2152-2162 Journal article (peer-reviewed)abstract © 2019 The Royal Society of Chemistry. In the combined lean NO x trap (LNT) and selective catalytic reduction (SCR) concept, the SCR catalyst can be exposed to rich conditions during deSO x of the LNT. Aging of Cu/SSZ-13 SCR catalysts, deposited on a cordierite monolith, was therefore studied in rich, lean and cycling lean/rich operations at 800 °C (lean condition: 500 ppm NO, 8% O 2 , 10% H 2 O and 10% CO 2 ; rich condition: 500 ppm NO, 1% H 2 , 10% H 2 O and 10% CO 2 ). The structure of the catalyst was investigated by X-ray diffraction (XRD), surface area measurements and scanning transmission electron microscopy (STEM). In general, aging decreased the SCR activity and NH 3 oxidation. However, rich conditions showed a very rapid and intense deactivation, while lean aging led to only a small low-temperature activity decrease. The XRD results showed no sign of structure collapse, but the number of active sites, as titrated by NH 3 temperature-programed desorption (NH 3 -TPD) and in situ DRIFTS, revealed an important loss of acid sites. NH 3 storage was significantly more depleted after rich aging than after lean aging. The Lewis sites, corresponding to exchange Cu 2+ , were preserved to some extent in lean conditions. Lean aging also decreased the enthalpy of NH 3 adsorption from -158 kJ mol -1 to -136 kJ mol -1 . Moreover, a comparison of aging in lean-rich cycling conditions with aging only in rich conditions revealed that adding lean events did not hinder or reverse the deactivation, and it was mainly the time in rich conditions that determined the extent of the deactivation. The STEM images coupled with elemental analysis revealed the formation of large Cu particles during rich aging. Conversely, Cu remained well dispersed after lean aging. These results suggest that the copper migration and agglomeration in large extra-framework particles, accelerated by the action of hydrogen, caused the observed severe deactivation.
11.	Auvray, Xavier, 1986, et al. (author) Stability and activity of Pd-, Pt- and Pd-Pt catalysts supported on alumina for NO oxidation 2015 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 168, s. 342-352 Journal article (peer-reviewed)abstract The association of palladium and platinum supported on alumina was studied for diesel oxidation catalyst application. The effect of propene, water and their combination on NO oxidation activity was investigated in flow reactor over Pt/Al2O3, Pd/Al2O3 and two Pt-Pd/Al2O3 catalysts, prepared by co-impregnation and sequential impregnation of the metals. Contrary to Pd/Al2O3, activity improvement due to the repetition of activity test was observed on Pt/Al2O3 and both Pt-Pd/Al2O3. Metal sintering during activity test was revealed by CO chemisorption. The bimetallic catalysts reached their final stability and activity before Pt/Al2O3. The presence of water decreased the NO oxidation activity of all catalysts and the propene completely inhibited NO oxidation at low temperature until propene combustion occurred. The addition of palladium to Pt/Al2O3 was found very efficient to oxidize propene and therefore significantly limited the inhibition of NO oxidation by propene. A mechanism was proposed to explain the NO oxidation promotion lying behind the addition of Pd. DRIFT measurements and flow reactor experiments showed that propene was less stable and able to react with surface nitrates on Pd-containing catalyst at low temperature (175 degrees C). On Pt/Al2O3, however, the propene consumption proceeded initially through selective catalytic reduction of NO, which took place at higher temperature (240 degrees C). In this way, propene combustion and consequently NO oxidation occurred at lower temperature on bimetallic catalysts than on Pt/Al2O3.
12.	Auvray, Xavier, 1986, et al. (author) The addition of alkali and alkaline earth metals to Pd/Al2O3 to promote methane combustion. Effect of Pd and Ca loading 2018 In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 299, s. 212-218 Journal article (peer-reviewed)abstract Methane catalytic combustion was studied on Pd/Al2O3 catalysts modified with alkali and alkaline earth metals (K, Na, Ca and Ba). Temperature-programmed reactions were performed in flow reactor on washcoated monolithic samples. CO chemisorption was carried out and BET surface area was measured in order to characterize the catalysts. Addition of alkaline metals was either beneficial or detrimental for methane oxidation, depending on the catalyst composition and pretreatment. High loading of alkaline modifiers and cooling in reaction mixture increased the light-off temperature of methane oxidation. However, promotion was achieved by doping with calcium after cooling in inert atmosphere. Furthermore, calcium doping was more beneficial in presence of NO, which inhibits the methane oxidation. Higher Pd loading enhanced CH4 oxidation, whereas the effect of calcium depends on Ca and Pd loading. Indeed, the promotion by calcium was more pronounced on catalysts with 5% Pd than with 2.5% Pd. On 2.5% Pd catalyst, high Ca loading was detrimental for CH4 oxidation. In contrary, on 5% Pd catalyst, even 1.51 wt% calcium (the highest loading used) induced promotion, which demonstrates a correlation between Ca: Pd ratio and promotion/inhibition effect. Samples with a mass ratio of 0.15 showed the best activity.
13.	Azis, Muhammad Mufti, 1983, et al. (author) Evaluation of H2 effect on NO oxidation over a diesel oxidation catalyst 2015 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 179, s. 542-550 Journal article (peer-reviewed)abstract The influence of H2 on NO oxidation over Pt/Al2O3 as a model DOC catalyst was evaluated with various DOC feed mixtures. Discrimination of surface chemistry and exothermal effects due to addition of H2 was made based on differences in time scales of transient responses. H2 was proposed to retard Pt oxide formation mainly at low temperatures (ca.
14.	De Abreu Goes, Jesus, 1989, et al. (author) Chapter 5: Mechanism and Kinetics of NOx Storage 2018 In: RSC Catalysis Series. - Cambridge : Royal Society of Chemistry. - 1757-6733 .- 1757-6725. ; 2018-January, s. 127-156 Book chapter (other academic/artistic)abstract In this chapter, experimental studies and kinetic models are presented to elucidate the fundamental mechanisms for NOxstorage on the NOxstorage and reduction (NSR) catalysts. A well-accepted reaction pathway for NOxstorage includes, as an initial step, the oxidation of NO to NO2under lean conditions, and subsequently storage on the NOxstorage sites in the form of nitrites or nitrates. NO can also be stored directly in the presence of NO and oxygen, in the so-called nitrite route. However, the NOxstorage process is largely influenced by the primary gas components in the exhaust stream, such as CO2, H2O and SO2. In particular, significant attention has been focused on sulphur poisoning and the interaction of SO2with different NSR components due to its large potential of harming NSR catalyst activity. Finally, a kinetic model describing in detail the sulphur poisoning over a commercial LNT catalyst is discussed. The model can well describe the gradual deactivation of the catalyst during sulphur exposure.
15.	De Abreu Goes, Jesus, 1989, et al. (author) Correlation between Vehicle- and Rapid- Aged Commercial Lean NOx Trap Catalysts 2017 In: SAE International Journal of Engines. - : SAE International. - 1946-3944 .- 1946-3936. ; 10:4, s. 1613-1626 Conference paper (other academic/artistic)abstract Even though substantial improvements have been made for the lean NOx trap (LNT) catalyst in recent years, the durability still remains problematic because of the sulfur poisoning and sintering of the precious metals at high operating temperatures. Hence, commercial LNT catalysts were aged and tested in order to investigate their performance and activity degradation compared to the fresh catalyst, and establish a proper correlation between the aging methods used. The target of this study is to provide useful information for regeneration strategies and optimize the catalyst management for better performance and durability. With this goal in mind, two different aging procedures were implemented in this investigation. A catalyst was vehicle-aged in the vehicle chassis dynamometer for 100000 km, thus exposed to real conditions. Whereas, an accelerated aging method was used by subjecting a fresh LNT catalyst at 800 °C for 24 hours in an oven under controlled conditions. Engine dynamometer studies were performed with a Volvo mid-sized diesel engine with the purpose of testing the NOx storage and reduction performance, as well as the THC and CO conversion activity of the catalysts under controlled conditions. The aged catalysts activity was shown to be significantly degraded, mainly at low working temperatures compared to the fresh LNT, and one reason for this could be limited NO oxidation. In addition, the oven-aged sample was found to be well correlated to the vehicle-aged catalyst. On top of that, several vehicle emission cycles were carried out in the vehicle chassis dynamometer with a 2.0 l Volvo XC90 diesel vehicle in order to study the catalysts performance under real driving conditions and monitor the gradual deterioration of the vehicle-aged catalyst during the vehicle aging testing.
16.	De Abreu Goes, Jesus, 1989, et al. (author) Detailed Characterization Studies of Vehicle and Rapid Aged Commercial Lean NOx Trap Catalysts 2018 In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 57:29, s. 9362-9373 Journal article (peer-reviewed)abstract Commercial lean NOxtrap (LNT) catalysts were aged and characterized to elucidate the effect of aging on their performances and examine the deactivation of a rapid-aged catalyst toward an improved correlation with respect to a vehicle-aged catalyst. Detailed characterization studies were carried out on the flow reactor with small cylindrical cores extracted from the commercial LNT catalysts. Physicochemical characterization techniques were also implemented. The catalyst evaluation revealed that aging resulted in a significant deterioration of NOxstorage and reduction functions as a consequence of precious metal sintering, loss of surface area of the NOxstorage and support materials, phase transitions of the adsorber compounds, and large accumulation of poison species. Among the aged samples examined, the middle (lengthwise) vehicle-aged sample showed the highest NOxconversion, while the oven-aged catalyst was the most active of the aged samples for water gas shift reaction and oxygen storage.
17.	De Abreu Goes, Jesus, 1989, et al. (author) Sulfur Poisoning Effects on Modern Lean NOx Trap Catalysts Components 2019 In: Catalysts. - : MDPI AG. - 2073-4344. ; 9:6 Journal article (peer-reviewed)abstract In the present work, a series of different materials was investigated in order to enhance the understanding of the role of modern lean NOx trap (LNT) components on the sulfur poisoning and regeneration characteristics. Nine different types of model catalysts were prepared, which mainly consisted of three compounds: (i) Al2O3, (ii) Mg/Al2O3, and (iii) Mg/Ce/Al2O3 mixed with Pt, Pd, and Pt-Pd. A micro flow reactor and a diffuse reflectance infrared Fourier transform spectrometer (DRIFTS) were employed in order to investigate the evolution and stability of the species formed during SO2 poisoning. The results showed that the addition of palladium and magnesium into the LNT formulation can be beneficial for the catalyst desulfation due mainly to the ability to release the sulfur trapped at relatively low temperatures. This was especially evident for Pd/Mg/Al2O3 model catalyst, which demonstrated an efficient LNT desulfation with low H-2 consumption. In contrast, the addition of ceria was found to increase the formation of bulk sulfate species during SO2 poisoning, which requires higher temperatures for the sulfur removal. The noble metal nature was also observed to play an important role on the SOx storage and release properties. Monometallic Pd-based catalysts exhibited the formation of surface palladium sulfate species during SO2 exposure, whereas Pt-Pd bimetallic formulations presented higher stability of the sulfur species formed compared to the corresponding Pt- and Pd-monometallic samples.
18.	Friberg, Ida, 1990, et al. (author) Complete methane oxidation over Ba modified Pd/Al2O3: The effect of water vapor 2018 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 231, s. 242-250 Journal article (peer-reviewed)abstract The effect on complete methane (CH 4 ) oxidation activity by an addition of up to 2 wt.% barium (Ba) promoter to alumina supported palladium (Pd/Al 2 O 3 , 2 wt.% Pd) was investigated. The catalyst samples were characterized with various techniques; temperature programmed oxidation (TPO), temperature programmed reduction with CH 4 (CH 4 -TPR), X-ray photoelectron spectroscopy (XPS), scanning transmission electron microscopy (STEM) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). Flow reactor was used to investigate the CH 4 oxidation activity in the presence and in the absence of water vapor and also to evaluate the possibility to regenerate the catalytic activity after water vapor exposure. The results from the TPO and the CH 4 -TPR experiments together with the XPS analysis gave no evidences for electronic promotion of the catalytic activity by addition of 0.5–2 wt.% Ba. This goes in line with the CH 4 conversion in dry gas condition, which was not affected by the Ba addition. However, we observed that an addition of Ba to Pd/Al 2 O 3 enhances the CH 4 oxidation activity in the presence of water vapor, hence mitigates the effect of water deactivation. Interestingly, it was also seen that after water vapor exposure, the CH 4 oxidation activity could be regenerated to greater extent for the Ba promoted samples, particularly for the regeneration temperatures of 500–600 °C. Our results clearly show that the support influences the water deactivation of the active palladium sites and that the addition of barium is beneficial for the catalyst regeneration.
19.	Friberg, Ida, 1990, et al. (author) The effect of Si/Al ratio of zeolite supported Pd for complete CH4 oxidation in the presence of water vapor and SO2 2019 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 250, s. 117-131 Journal article (peer-reviewed)abstract The catalytic properties of palladium supported on H-beta and H-SSZ-13 zeolite with different silica to alumina ratio (SAR) have been evaluated for complete CH 4 oxidation in the presence and absence of water vapor and together with SO 2 . Different SAR was successfully obtained by dealumination of the zeolites in an acidic solution at elevated temperature. Flow reactor experiments showed that the SAR of the zeolite support greatly impacts the catalytic activity, especially in the presence of water vapor. Pd supported on a highly siliceous beta zeolite expressed high and stable CH 4 conversion in the presence of water vapor, whereas the activity for Pd supported on zeolites with low SAR or Al 2 O 3 decreased over time due to accumulative water deactivation. Hence, an increased SAR of the zeolite support clearly correlates to a lower degree of water deactivation. We suggest that this is a result of the high hydrophobicity of the siliceous zeolites. The results also imply that the catalytic activity in the presence of water vapor is influenced more by the SAR than the type of the zeolite framework. The CH 4 oxidation activity was also enhanced with increasing SAR under dry conditions. This was addressed to the formation of more Pd particles in relation to ion-exchanged Pd 2+ species and changes of the oxidation-reduction behavior of the Pd. The high number of acidic sites in zeolites with low SAR provided higher dispersion of Pd particles and formation of more monoatomic Pd 2+ species, whereas almost exclusively Pd particles of larger sizes were formed on the highly siliceous zeolites. The monoatomic Pd 2+ species, mostly formed on zeolites with low SAR, were oxidized and reduced at significantly higher temperatures than Pd in the particle form. Hence, complete reduction or oxidation of the Pd supported on highly siliceous zeolites can be achieved at lower temperatures. Moreover, compared to Pd/Al 2 O 3 , the zeolite supported Pd expressed higher sensitivity to SO 2 . However, the major part of the catalytic activity could be regenerated more easily using siliceous zeolites as supports compared to Al 2 O 3 . We suggest that this is an effect of the lower SO 2 adsorption on the zeolite supports than on the Al 2 O 3 support, which results in the formation of more PdSO x species upon SO 2 exposure. On the other hand, the low SO 2 adsorption on the zeolites also results in less spillover of sulfur species from the support to the active PdO, which explains the facilitated regeneration.
20.	Funkenbusch, Li Lu T., et al. (author) Catalytic hydrotreatment of pyrolysis oil phenolic compounds over Pt/Al2O3 and Pd/C 2019 In: Fuel. - : Elsevier BV. - 0016-2361. ; 243, s. 441-448 Journal article (peer-reviewed)abstract A batch catalytic slurry reactor system was used to study the hydrodeoxygenation (HDO) of pyrolysis oil model compounds at high conversions and conditions similar to petroleum hydrotreatment reactors. The lignin fraction of pyrolysis oil was represented in this study by anisole, m-cresol and phenol, both individually and blended in pairs. Experiments were run from 250 °C to 350 °C using platinum on alumina (Pt/Al2O3) or palladium on carbon (Pd/C) in a Parr reactor at 50 bar. The Pt/Al2O3 catalysts exhibited ring saturation, demethylation and hydrodeoxygenation, with temperature-dependent pathway shifts. Tests with blended pairs yielded no secondary reactions but competitive adsorption for catalyst active sites was observed. Tests with Pd/C showed ring saturation followed by methanol abstraction. Rate constants and adsorption parameters were fitted to a Langmuir-Hinshelwood model for each catalyst and compound. Arrhenius relationships for those rate constants and surface adsorption parameters were then calculated. When used in a slurry reactor model with catalyst-specific reaction data, the product composition, hydrogen consumption, and energy requirements are well predicted for a known feed and set of reactor conditions.
21.	Grönqvist, Helena, 1975-, et al. (author) Fifteen Challenges in Establishing a Multidisciplinary Research Program on eHealth Research in a University Setting : A Case Study 2017 In: Journal of Medical Internet Research. - : JMIR Publications Inc.. - 1438-8871. ; 19:5 Journal article (peer-reviewed)abstract BACKGROUND:U-CARE is a multidisciplinary eHealth research program that involves the disciplines of caring science, clinical psychology, health economics, information systems, and medical science. It was set up from scratch in a university setting in 2010, funded by a governmental initiative. While establishing the research program, many challenges were faced. Systematic documentation of experiences from establishing new research environments is scarce.OBJECTIVE:The aim of this paper was to describe the challenges of establishing a publicly funded multidisciplinary eHealth research environment.METHODS:Researchers involved in developing the research program U-CARE identified challenges in the formal documentation and by reflecting on their experience of developing the program. The authors discussed the content and organization of challenges into themes until consensus was reached.RESULTS:The authors identified 15 major challenges, some general to establishing a new research environment and some specific for multidisciplinary eHealth programs. The challenges were organized into 6 themes: Organization, Communication, Implementation, Legislation, Software development, and Multidisciplinarity.CONCLUSIONS:Several challenges were faced during the development of the program and several accomplishments were made. By sharing our experience, we hope to help other research groups embarking on a similar journey to be prepared for some of the challenges they are likely to face on their way.
22.	Klionsky, Daniel J, et al. (author) Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition). 2016 In: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 12:1, s. 1-222 Journal article (peer-reviewed)
23.	Kubiak, L., et al. (author) Mechanistic investigation of the reduction of NOx over Pt-and Rh-based LNT catalysts 2016 In: Catalysts. - : MDPI AG. - 2073-4344. ; 6:3, s. Art. no. 46- Journal article (peer-reviewed)abstract The influence of the noble metals (Pt vs. Rh) on the NOx storage reduction performances of lean NOx trap catalysts is here investigated by transient micro-reactor flow experiments. The study indicates a different behavior during the storage in that the Rh-based catalyst showed higher storage capacity at high temperature as compared to the Pt-containing sample, while the opposite is seen at low temperatures. It is suggested that the higher storage capacity of the Rh-containing sample at high temperature is related to the higher dispersion of Rh as compared to Pt, while the lower storage capacity of Rh-Ba/Al2O3 at low temperature is related to its poor oxidizing properties. The noble metals also affect the catalyst behavior upon reduction of the stored NOx, by decreasing the threshold temperature for the reduction of the stored NOx. The Pt-based catalyst promotes the reduction of the adsorbed NOx at lower temperatures if compared to the Rh-containing sample, due to its superior reducibility. However, Rh-based material shows higher reactivity in the NH3 decomposition significantly enhancing N2 selectivity. Moreover, formation of small amounts of N2O is observed on both Pt- and Rh-based catalyst samples only during the reduction of highly reactive NOx stored at 150 °C, where NOx is likely in the form of nitrites.
24.	Leistner, Kirsten, 1984, et al. (author) Ammonia Desorption Peaks Can Be Assigned to Different Copper Sites in Cu/SSZ-13 2017 In: Catalysis Letters. - : Springer Science and Business Media LLC. - 1572-879X .- 1011-372X. ; 147:8, s. 1882-1890 Journal article (peer-reviewed)abstract The purpose of this study is to attribute NH 3 -TPD peaks observed over Cu/SSZ-13 catalysts to different catalytic sites. This is done by comparing a large number of copper loadings, especially below 40% ion exchange, to be able to see effects relevant to sites in both 6-membered and 8-membered rings. We found that intermediate (200–300 °C) and high (400–500 °C) temperature NH 3 -TPD peaks followed similar trends to the copper species in 6-membered and 8-membered rings respectively, as seen by H 2 -TPR and NO-DRIFTS. Thus we propose that these two TPD peaks represent ammonia stored on H and Cu sites in 6 and 8-membered rings, respectively. This assignment is further supported by the finding that the intermediate and high temperature NH 3 -TPD peaks of samples with different Si/Al ratios also follow the same trend. Moreover, we observe that the activation energy for ammonia oxidation is significantly lower for Cu in 6MR compared to Cu in 8MR rings. Graphical Abstract: [Figure not available: see fulltext.].
25.	Leistner, Kirsten, 1984, et al. (author) Comparison of Cu/BEA, Cu/SSZ-13 and Cu/SAPO-34 for ammonia-SCR reactions 2015 In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 258, s. 49-55 Journal article (peer-reviewed)abstract In this study, the ammonia-SCR process was investigated using 2.5 wt.% Cu/BEA, 2.6 wt.% Cu/SAPO-34 and 3.1 wt.% Cu/SSZ-13. Several reactions such as NO oxidation, ammonia oxidation, standard SCR, fast SCR and NO2 SCR were studied to understand the effect of zeolite type. It was found that the small-pore zeolites/silicoaluminophosphates with CHA structure (Cu/SAPO-34 and Cu/SSZ-13) exhibited higher SCR activity at 150°C and lower selectivity toward N2O formation during standard SCR conditions than Cu/BEA. However, formation of ammonium nitrate species during fast SCR conditions at 150°C occurred over Cu/CHA catalysts, which resulted in a gradual decrease of the NOx conversion. Such blocking was also observed over Cu/BEA, albeit to a minor extent. The ammonium nitrate formation and its decomposition temperature regimes resulted in that the Cu/BEA was catalytically more active at lower temperature than either Cu/SAPO-34 or Cu/SSZ-13 during fast SCR conditions. Additionally, our results show that the ammonium nitrate species were more stable on the small-pore zeolites than on Cu/BEA. Comparing the two Cu/CHA catalysts, Cu/SAPO-34 and Cu/SSZ-13, it was found that ammonia oxidation at high temperatures and ammonia SCR at 150°C was higher on Cu/SAPO-34. Further, TPR experiments showed that Cu in Cu/SAPO-34 is more easily reduced compared to Cu/SSZ-13. This can facilitate the redox processes and can thereby be a reason for the higher activity at 150°C for Cu/SAPO-34. In addition, Cu/SAPO-34 forms less N2O and this might be a result of the formation of more stable ammonium nitrates. To conclude, the choice of the type of zeolite/silicoaluminophosphates affects the activity and selectivity of the different steps in the SCR process.
26.	Leistner, Kirsten, 1984, et al. (author) Deactivation of Cu/SAPO-34 during low-temperature NH3-SCR 2015 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 165, s. 192-199 Journal article (peer-reviewed)abstract The sensitivity of NH3-SCR activity to water vapour at 70 degrees C is tested for Cu/SAPO-34 (morph.) catalysts. The synthesised Cu/SAPO-34 (morph.) is remarkably susceptible to low-temperature activity loss. After only 3 hat 70 degrees C, the NOx conversion decreases from an initial 87% to 66% at 200 degrees C, after another 9 h to 6%. This deactivation is accompanied by a partial loss of microporous volume, but the SAPO-34 framework remains crystalline. We postulate that a transformation of the active copper sites into an inactive form could be the cause for the deactivation. Regeneration of the catalyst was attempted, but had no impact on activity.
27.	Leistner, Kirsten, 1984, et al. (author) Impact of Copper Loading on NH3-Selective Catalytic Reduction, Oxidation Reactions and N2O Formation over Cu/SAPO-34 2017 In: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 10:4 Journal article (peer-reviewed)abstract We developed a procedure for aqueous ion exchange to obtain different Cu loadings of Cu/SAPO-34 (between 0 and 2.6 wt %). The catalysts were washcoated on monoliths and characterised with respect to their activity and selectivity under standard selective catalytic reduction (SCR), fast SCR, NH3 oxidation and NO oxidation reactions. They were further characterised using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), H-2-temperature programmed reduction (H-2-TPR), ultraviolet (UV)-vis spectroscopy and NH3 adsorption. As expected, activity of all reactions increased with copper loading, due to increased number of active sites. However, the N2O formation during standard and fast SCR yielded interesting mechanistic information. We observed that N2O formation at low temperature increased with copper loading for the standard SCR reaction, while it decreased for fast SCR. The low-temperature N2O formation during fast SCR thus occurs predominantly over Bronsted sites. Species responsible for N2O formation during standard SCR, on the other hand, are formed on the copper sites. We further found that the fast SCR reaction occurs to a significant extent even over the H/SAPO-34 form. The Bronsted sites in SAPO-34 are thus active for the fast SCR reaction.
28.	Leistner, Kirsten, 1984, et al. (author) Mechanistic study of hydrothermally aged Cu/SSZ-13 catalysts for ammonia-SCR 2018 In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 307, s. 55-64 Journal article (peer-reviewed)abstract The impact of hydrothermal ageing on the copper sites, crystalline order and critical reactions of a Cu/SSZ-13 was studied. The investigated catalyst had a low Si/Al ratio of 3.7 and was underexchanged at 65%. We propose that this catalyst had nearly saturated ion exchange positions in the 6-membered ring units (6MR) with copper ions, but still contained a significant amount of protonic sites in the large cages (8MR units). Investigation of a broad range of ageing temperatures (550-850 degrees C) allowed us to observe that no significant number of copper ions moved from the large cages into the 6MR units. Nevertheless, the Cu ions experienced a significant increase in reducibility above ageing temperatures of 700 degrees C. However, these changes appeared not to have a large impact on catalyst activity, which was more significantly correlated with long and short-range loss of crystallinity. Thus dealumination occurred at all temperatures above 550 degrees C and was correlated with significantly reduced ammonia storage capacity and ammonia oxidation ability. Low-temperature SCR activity was not much affected below 850 degrees C, but decreased significantly when total collapse of the zeolite framework occurred at this temperature. At ageing temperatures above 750 degrees C, formation of oxidic copper species was observed and correlated partially with increased high-temperature ammonia oxidation capacity, though it is possible that oxidation in parallel occurs on non-oxidic sites in ion-exchange positions. On the other hand, low-temperature ammonia oxidation was shown to occur on ionic copper sites (likely in the 6MR units) and decrease with increasing ageing temperature. We further found some evidence that low-temperature formation of N2O during standard SCR may occur on different sites or via different mechanisms.
29.	Leistner, Kirsten, 1984, et al. (author) Volatilisation and subsequent deposition of platinum oxides from diesel oxidation catalysts 2019 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 241, s. 338-350 Journal article (peer-reviewed)abstract In this study, we have reproduced a DOC-upstream-of-SCR configuration in the laboratory, with washcoated model Pt/Al2O3, Pd-Pt/Al2O3and Pd/Al2O3catalysts, as well as a commercial DOC, upstream of an alumina-washcoated core. We studied vapour-phase noble metal poisoning of the alumina core, as noble metal from the model DOC catalysts deposited on the downstream alumina core. The mobile species were predominantly volatile platinum oxides, whereas Pd volatilised in such small traces that it was close or below detection limit by Inductively Coupled Plasma – Sector Field Mass Spectrometry (ICP-SFMS), even when the model DOC had only Pd as active species. Even after volatilisation at temperatures as low as 550 °C, the deposited trace amounts of noble metal were highly active for ammonia oxidation. The deposited platinum appears to be finely dispersed, but when subjected to reaction conditions, it likely undergoes sintering, causing a further increase of the ammonia oxidation ability, which will affect the extent of poisoning in a real exhaust aftertreament system. We investigated the dependence of volatilization on temperature, and, as predicted, found it to be exponential. Exposure to increasing temperatures causes different degrees of sintering of the noble metal particles and we found qualitative evidence that sintering decreases the amount of volatilisation. Adding a small amount of Pd (Pd:Pt = 0.5:1) to the catalyst had no effect on volatilisation. However, larger Pd concentrations (Pd:Pt = 1:1 or 2:1) decrease volatilisation. The results for the model DOCs were confirmed by volatilisation from a commercial DOC, where in fact the capturing core exhibited even higher ammonia oxidation ability compared to those downstream of the model DOCs, after evaporation at 700 °C.
30.	Mihai, Oana, 1975, et al. (author) Adsorption and Oxidation Investigations over Pt/Al2O3 Catalyst: A Microcalorimetric Study 2016 In: Catalysts. - : MDPI AG. - 2073-4344. ; 6:5, s. Art. no. 73- Journal article (peer-reviewed)abstract The differential adsorption heats of oxygen and NO, as well as catalytic oxidation behavior during NO oxidation and NO2 dissociation reactions over supported Pt-catalysts, were investigated by microcalorimetric measurements. The average heat of adsorption (Delta H) of oxygen ranged from 310 kJ/mol at 200 degrees C to 289 kJ/mol at 400 degrees C. Over this temperature range formation of platinum oxides and coverage dependence caused variations in the apparent heat of adsorption. NO heat of adsorption from 50 to 150 degrees C was near constant with an average value of 202 kJ/mol over the temperature range.
31.	Mihai, Oana, 1975, et al. (author) Evaluation of an Integrated Selective Catalytic Reduction-Coated Particulate Filter 2015 In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 54:47, s. 11779-11791 Journal article (peer-reviewed)abstract In this study, an SCR-coated particulate filter with soot loaded from engine bench experiments was evaluated. Prior to soot loading, the sample was hydro-thermally aged at 850 degrees C. Flow reactor measurements were performed under various reaction conditions to examine the impact of soot in an SCR-coated diesel particulate filter (DPF) on standard SCR, fast SCR, NH3 oxidation, and NO oxidation. In the presence of soot, NOx conversion was slightly lower at 200-300 degrees C due to the blocking of active sites. However, at higher temperatures, the NOx conversion was somewhat higher with soot, indicating that soot more strongly inhibited the oxidation of NH3 than the SCR reaction. When feeding equal amounts of NO and NO2 together with NH3, ammonium nitrates on the sample were formed. The presence of soot significantly decreased the formation or the stability of ammonium nitrate, resulting in higher conversion with soot. To further understand this interesting aspect, ammonium nitrate formation and decomposition experiments using model Cu/BEA catalyst with and without soot were performed. It was observed that less N2O was formed in the presence of soot, and this in combination with COx formation during the ammonium nitrate formation step suggested that soot reacted with the ammonium nitrates, and we propose that this occurs on CuO species on the outside of the zeolite particles.
32.	Mihai, Oana, 1975, et al. (author) The effect of changing the gas composition on soot oxidation over DPF and SCR-coated filters 2018 In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 306, s. 243-250 Journal article (peer-reviewed)abstract In this study, we have investigated the effect of changing the gas feed composition on soot oxidation over diesel particulate filter (DPF) and SCR-coated filter during temperature ramp experiments from 200 to 750 degrees C. For DPF, the increasing NO2/NOx ratio promoted soot oxidation across a fairly low temperature range (200-500 degrees C) and, in addition, soot oxidation was enhanced by water. Interestingly, the presence of NH3 in the gas feed inhibited the soot oxidation under various feed compositions for the DPF. Moreover, ammonia oxidation was also observed over the filter and based on these experiments together with experiments without soot, we conclude that ammonia oxidation is actually occurring on soot particles and that the interaction of the ammonia with the soot is inhibiting soot oxidation. Further, fast and NO2 SCR reactions were found to occur on soot particles, while no reactions with NO under standard SCR conditions was observed. Thus, the NH3 and NO2 molecules are interacting with the soot. When comparing the DPF and SCR-filter we found that the SCR material enhanced the soot oxidation under standard and fast SCR conditions, because of the fact that soot oxidation was inhibited by NH3 and would be rapidly consumed under SCR reactions with the Cu-zeolite in the SCR-filter. Furthermore, during fast SCR conditions, because NO2 is consumed during fast SCR reaction for the SCR-filter, the opposite results were found where soot oxidation occurred at lower temperature for the DPF. (c) 2017 Elsevier B.V. All rights reserved.
33.	Mihai, Oana, 1975, et al. (author) The Effect of Si/Al Ratio for Pd/BEA and Pd/SSZ-13 Used as Passive NOx Adsorbers 2018 In: Topics in Catalysis. - : Springer Science and Business Media LLC. - 1572-9028 .- 1022-5528. ; 61:18-19, s. 2007-2020 Journal article (peer-reviewed)abstract The mitigation of cold-start emissions involves the development of passive NOx adsorbers (PNA) systems that store NOx at low temperature, being designed to release the trapped NOx at higher temperatures, where downstream NOx reduction catalysts are efficient. Pd-based zeolites (BEA, SSZ-13) with different SAR (Si-to-Al ratio) were used for PNA investigation, and Pd/Ce/Al2O3 catalyst was used as a reference for comparison. In this study, NOx adsorption is investigated at low temperature (80 °C) and it is released during a temperature ramp (to 400 °C) under various gas feed composition. Moreover, detailed characterization was performed using BET, XRD, XPS, TPO, STEM and ICP-SFMS and the stored NO species was studied using in-situ DRIFTS. The addition of CO to the storage mixture resulted in that for Pd/zeolites with low and medium SAR the binding energy for NO was increased. In addition, NO was stored in larger quantities, especially for the Pd/SSZ-13 samples. However, for Pd/BEA (SAR = 300) no such stable NO species was formed and for Pd/Ce/Al2O3 the CO addition was even negative. Moreover, in-situ NO DRIFTS showed that there was large amount of nitrosyls on ionic palladium for the Pd/zeolites with low and medium SAR, indicating that a significant fraction of the palladium was in ion-exchanged positions, while this peak was small for the Pd/BEA (SAR = 300) and non-existing for Pd/Ce/Al2O3. Thus, CO addition is beneficial for Pd species that are in ion-exchanged positions, but this is not the case for Pd particles and this can explain the observations that CO is only beneficial for Pd/zeolites with low and medium SAR. Moreover, experiments with similar SAR [Pd/BEA (SAR = 25) and Pd/SSZ-13 (SAR = 24)], showed that there is larger stability of the stored NOx in the small pore Pd/SSZ-13.
34.	Mihai, Oana, 1975, et al. (author) The effect of soot on ammonium nitrate species and NO2 selective catalytic reduction over Cu-zeolite catalyst-coated particulate filter 2016 In: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2061 Journal article (peer-reviewed)abstract A selective catalytic reduction (SCR)-coated particulate filter was evaluated by means of dynamic tests performed using NH3, NO2, O-2 and H2O. The reactions were examined both prior to and after soot removal in order to study the effect of soot on ammonium nitrate formation and decomposition, ammonia storage and NO2 SCR. A slightly larger ammonia storage capacity was observed when soot was present in the sample, which indicated that small amounts of ammonia can adsorb on the soot. Feeding of NO2 and NH3 in the presence of O-2 and H2O at low temperature (150, 175 and 200 degrees C) leads to a large formation of ammonium nitrate species and during the subsequent temperature ramp using H2O and argon, a production of nitrous oxides was observed. The N2O formation is often related to ammonium nitrate decomposition, and our results showed that the N2O formation was clearly decreased by the presence of soot. We therefore propose that in the presence of soot, there are fewer ammonium nitrate species on the surface due to the interactions with the soot. Indeed, we do observe CO2 production during the reaction conditions also at 150 degrees C, which shows that there is a reaction with these species and soot.
35.	Mihai, Oana, 1975, et al. (author) The effect of water on methane oxidation over Pd/Al2O3 under lean, stoichiometric and rich conditions 2017 In: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 7:14, s. 3084-3096 Journal article (peer-reviewed)abstract In this study, the effect of oxygen concentration and the presence of water on methane oxidation were examined over a Pd/Al2O3 catalyst. The physicochemical properties of the catalyst were investigated in detail using BET, XRD, STEM, O-2-TPO and CH4-TPR. Ramping experiments from 150 to 700 degrees C were conducted using rich, stoichiometric and lean gas mixtures in the absence and presence of water. It was found that increasing the oxygen concentration in a dry atmosphere resulted in higher methane oxidation activity, which can be connected to the facilitation of palladium oxide formation. The TPO data showed that only minor amounts of PdO up to 700 degrees C were decomposed; however, in the stoichiometric and rich reaction mixture, PdO was still decomposed because of the oxygen limitation. This fact resulted in a "negative activation" during cooling, with increased activity because of palladium re-oxidation. Moreover, methane steam reforming and water gas shift reactions were important reactions under rich conditions over the metallic palladium sites. A significant inhibiting effect of water on the Pd-catalyst with loss of methane activity was found. Interestingly, the inhibition effect was much greater using high oxygen concentration in the gas mixture (500 ppm CH4, 8% O-2, 5% H2O) than that at lower oxygen levels (800-1200 ppm) and we propose that the hydroxyl species formation, which blocks the active sites, are facilitated by a large oxygen excess. In addition, the re-oxidation of palladium occurring during the cooling ramp in dry feed using rich and stoichiometric gas mixtures was also significantly suppressed in the presence of a large amount of water. Thus, water impedes the oxidation of palladium, which significantly deactivates the Pd catalyst.
36.	Ojagh, Houman, 1976, et al. (author) Effect of Dimethyl Disulfide on Activity of NiMo Based Catalysts Used in Hydrodeoxygenation of Oleic Acid 2017 In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 56:19, s. 5547-5557 Journal article (peer-reviewed)abstract Alumina supported NiMo catalysts were synthesized. The prepared NiMo catalysts were activated by DMDS in a sulfidation process and characterized. The sulfided NiMo catalysts were next used in hydrodeoxygenation (HDO) of oleic acid in a batch reactor. Afterward, the NiMo catalysts were recovered and used in another set of HDO reactions of oleic acid under the same conditions used in the previous HDO reactions. After the HDO experiments, the active phase and deposited coke on spent catalysts were characterized. The results indicated that higher concentrations of DMDS promoted the production of heptadecane (C-17) but had no effect on the production of octadecane (C-18). Moreover, the XPS results revealed the promotional effect of DMDS concentration on maintenance of the sulfidity of the catalysts. In addition, the results for the experiments with the second run catalyst revealed a clear deactivation due to increased coke depositions. Furthermore, after two repeated experiments with first run and second run catalysts, it was observed that coke formation decreased when the concentration of DMDS was increased. These results dearly indicate a correlation between the concentration of DMDS and coke formation.
37.	Ojagh, Houman, 1976, et al. (author) Effect of Thermal Treatment on Hydrogen Uptake and Characteristics of Ni-, Co-, and Mo-Containing Catalysts 2015 In: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 54:46, s. 11511-11524 Journal article (peer-reviewed)abstract Nonsulfided alumina supported Ni, Co, Mo, NiMo, and CoMo hydrotreating catalysts were synthesize. The TEM results indicated low dispersions of the active metals for Mo, NiMo, and CoMo, samples but significantly higher dispersion for the Ni sample. The effect of calcination and reduction on the hydrogen uptake capacity of the samples was investigated. The H-2-chemisorption and XPS results together showed that the precalcination step had a detrimental effect on the hydrogen absorption of the Ni sample formation of stable metal oxides. The XPS results revealed that the metal oxides of all calcined samples reached with the alumina support to form very stable spinels. Futher, the positive effects of a hydrogen atmosphere during the reduction, on the hyderogen uptake of the samples were cinfirmed by H-2-chemisorption measurements. Finally, the heats of adsorption (Delta H) of hydrogen for the Ni and Co samples were calculated to be 140 and 98 kJ mol(-1), respectively.
38.	Ojagh, Houman, 1976, et al. (author) Hydroconversion of abietic acid into value-added fuel components over sulfided NiMo catalysts with varying support acidity 2019 In: Fuel Processing Technology. - : Elsevier BV. - 0378-3820. ; 190, s. 55-55-66 Journal article (peer-reviewed)abstract The hydroconversion of abietic-type rosin acids, with a tri-ring structure into mono-ring structure hydrocarbons, was investigated. The reactions were performed at 380 °C under 7500 kPa of H2 pressure over sulfided NiMo catalysts supported on alumina, USY-zeolite and mixed alumina/USY-zeolite. The NiMo supported catalysts were characterized using N2-physisorption, ethylamine-temperature programmed desorption (ethylamine-TPD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and temperature programmedoxidation (TPO). The sulfided NiMo supported on only USY-zeolite showed the highest selectivity towards production of the mono-ring hydrocarbons such as methyl cyclopentane due to the strong Brønsted acid character of USY-zeolite. Whereas, the sulfided NiMo supported on alumina with weaker Brønsted acidity showed strong selectivity towards the di and tri-ring hydrocarbons such as dimethyl tetralins and retene. Moreover, the selectivities towards the mono-ring hydrocarbons over the NiMo catalysts with mixed supports were lower with a higher alumina content. Finally, the results show that the sulfided NiMo catalyst supported on alumina/USY-zeolite support with 50 wt% zeolite achieved a good level of deoxygenation, ring opening and cracking of the rosin acid while avoiding excessive coke formation.
39.	Ojagh, Houman, 1976, et al. (author) The effect of rosin acid on hydrodeoxygenation of fatty acid 2019 In: Journal of Energy Chemistry. - : Elsevier BV. - 2095-4956. ; 28, s. 85-94 Journal article (peer-reviewed)abstract In this study, inhibition of tall oil fatty acid hydrodeoxygenation (HDO) activity due to addition of rosin acid over sulfided NiMo/Al2O3 was investigated. Oleic acid and abietic acid were used as model compounds for fatty acid and rosin acid respectively in tall oil. After completion of each HDO experiment, the NiMo catalysts were recovered and used again under the same conditions. The results showed that the oleic acid HDO activity of sulfided catalysts was inhibited by addition of abietic acid due to competitive adsorption and increased coke deposition. The rate of carbon deposition on the catalysts increased when abietic acid was added to oleic acid feed. Moreover, the coke was in a more advanced form with higher stability for the catalysts exposed to both oleic acid and abietic acid. Furthermore, a clear correlation between the rate of coke formation and concentration of abietic acid was observed.
40.	Olsson, Louise, 1974, et al. (author) A kinetic model for sulfur poisoning and regeneration of Cu/SSZ-13 used for NH3-SCR 2016 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 183, s. 394-406 Journal article (peer-reviewed)abstract In this study, we have developed a multi-site kinetic model that describes the sulfur poisoning and gradual sulfur removal over Cu/SSZ-13 used for NH3-SCR. Sulfur poisoning was conducted under SCR conditions and thereafter, repeated SCR experiments were conducted to examine the effect of such poisoning and the subsequent gradual removal of sulfur. In addition, the effect of sulfur poisoning was examined on NH3 TPD and ammonia oxidation experiments. The following sites were used in the kinetic model: copper in the six-membered rings as described by S1Cu, copper in the larger cages with S2 and S3 as a site where physisorbed ammonia can attach. Further, ammonia was also adsorbed on the Brönsted sites, represented by S1Brön in the model, but in order not to further complicate the model, small amounts of ammonia storage on Brönsted sites were also lumped into S2. In the model, SO2 was adsorbed on the sites containing copper, which are S1Cu and S2. It should be noted that S1Cu and S2 represents hydrated copper sites. Interestingly, we observed experimentally that ammonia storage was larger after sulfur poisoning compared to before, which is why we added ammonia storage and desorption to the S1Cu-SO2 and S2-SO2 sites. However, ammonia was already adsorbing on the copper site; thus, these steps did not result in increased storage. Consequently, reaction steps were added where additional ammonia was adsorbed to form S1Cu-SO2-(NH3)2 and S2-SO2-(NH3)2 species, which could be interpreted as precursors to ammonium sulfates. Another aspect that must be addressed in the model is the observation in the literature that SO2 is more easily desorbed in SO2+NH3+O2 TPD than SO2+O2 TPD. Reversible reaction steps were therefore added whereby the S1Cu-SO2-NH3 and S2-SO2-NH3 species were decomposed to form SO2. A final reaction step was incorporated into the model to describe the SCR reaction with ammonia attached to the sulfur sites. The developed model could well describe the sulfur poisoning and gradual regeneration during repeated SCR experiments. In addition, the model well described the NH3 TPD and NH3 oxidation before and after sulfur poisoning.
41.	Olsson, Louise, 1974, et al. (author) A multi-site kinetic model for NH3-SCR over Cu/SSZ-13 2015 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 174, s. 212-224 Journal article (peer-reviewed)abstract In this study, we have developed a kinetic model for ammonia-SCR over a well-characterized Cu/SSZ-13 catalyst. It was found that a three-site model was needed in order to describe the ammonia temperature programmed desorption (TPD) with adsorption at 50 and 150 degrees C as well as ammonia oxidation, and NH3-SCR up to 600 degrees C. Based on literature studies, where detailed characterization of Cu/SSZ-13 have been conducted using several experimental techniques', we suggest the following physical interpretation of the S1 and S2 sites in the model. The S1 sites are associated with copper located in a six-membered ring, possibly slightly distorted due to interactions with-water and ammonia while, the S2 sites represent copper in the large cages or CuxOy species. In addition, ammonia is also stored on Bronsted acid sites, but in order not to complicate the model further, it was lumped together in the S1 and S2 sites. Finally, S3 sites have been added in order to describe the large amount of physisorbed ammonia at low temperature. This three-site model was capable of adequately describing the ammonia TPD experiments with the initial temperature of 50 and 150 degrees C. The heats of adsorption of ammonia on the Si and S2 sites were determined using micro-calorimeter experiments. Further, the main SCR reaction in the model occurs on S1 sites and the main ammonia oxidation reaction on S2 sites. However, due to the complex behavior associated with ammonia oxidation, where the conversion slightly decreased when the temperature was increased from 350 to 400 degrees C, an ammonia oxidation reaction occurring at low temperature with low rate needed to be introduced on S1. In a similar way, an added step was needed for ammonia-SCR on S2, which occurred at high temperature where the ammonia coverage on Si was low resulting in low conversion. To summarize, the-three-site model developed was capable of well describing the ammonia storage and release, ammonia oxidation as well as SCR and N2O formation across a broad temperature interval (100-600 degrees C).
42.	Sadokhina, Nadezda, 1985, et al. (author) An Experimental and Kinetic Modelling Study for Methane Oxidation over Pd-based Catalyst: Inhibition by Water 2017 In: Catalysis Letters. - : Springer Science and Business Media LLC. - 1572-879X .- 1011-372X. ; 147:9, s. 2360-2371 Journal article (peer-reviewed)abstract The water inhibition of methane oxidation over a bimetallic Pt-Pd on CeO2-Al2O3 catalyst was investigated and the experimental data were used to develop a kinetic model, consisting of only three reaction steps. In the model, the water effect was assigned to the adsorption of H2O on surface sites, as well as to the formation and accumulation of surface hydroxyl groups. These two effects were accounted by the model, which could well describe the experimental data obtained under various conditions.
43.	Sadokhina, Nadezda, 1985, et al. (author) Deceleration of SO2 poisoning on PtPd/Al2O3 catalyst during complete methane oxidation 2018 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 236, s. 384-395 Journal article (peer-reviewed)abstract The inhibiting effect of SO2 on the catalytic activity of the monometallic Pt/Al2O3 and Pd/Al2O3, as well as on bimetallic PtPd/Al2O3 catalyst for the complete oxidation of methane under lean conditions has been studied. Flow reactor experiments, in-situ DRIFT spectroscopy and characterization with XPS, STEM-EDX were performed. It was found that the addition of Pt to the Pd/Al2O3 resulted in a catalyst that was more robust towards sulfur poisoning. XPS results revealed residual sulfates on catalyst surface after regeneration. This was confirmed with EDX analysis, which demonstrated that sulfur was accumulated in noble metal particles and especially in the region of the particle rich in Pt. Although the catalyst has been deactivated in the presence of both SO2 and H2O, an additional presence of NO in the gas mixture of reactants resulted in an increased lifetime of the sample under reaction conditions. This NO effect strongly depends on the temperature of experiments and is most intense at a temperature close to 550 degrees C A postponed inhibition caused by the addition of NO may be explained by the DRIFTS results, which demonstrated that the presence of NO lowers the sulfate formation and mostly surface sulfites are observed that increase the lifetime of the catalyst during SO2 exposure.
44.	Sadokhina, Nadezda, 1985, et al. (author) Methane oxidation over Pd containing catalysts for lean and stoichiometric conditions 2017 Conference paper (other academic/artistic)
45.	Sadokhina, Nadezda, 1985, et al. (author) The influence of gas composition on Pd-based catalyst activity in methane oxidation - inhibition and promotion by NO 2017 In: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 200, s. 351-360 Journal article (peer-reviewed)abstract The individual influence, as well as the combined effect of H2O and NO on the activity of Pd/Al2O3, PtPd/Al2O3 and PtPd/CeAl2O3 catalysts in complete methane oxidation under lean conditions were investigated. Under temperature-programmed ramping experiments the activity was severely inhibited in the presence of 5 vol.% H2O in the reaction mixture. We propose that this is due to blocking by both water and hydroxyl species. Under the influence of NO without water in the gas flow, it was found that the methane oxidation activity was partly suppressed, due to blocking of active sites. Indeed TPD performed after ramping experiments showed NOx storage on the catalyst. Contrary to the negative effect of NO in the dry case, the promotional NO effect on the activity was observed when water was co-fed, comparing the case with only water presence. The promotional NO effect was confirmed with isothermal experiments, where e.g. the methane conversion decreased from initial 96% to 25% after 10 h of exposure in CH4-O-2-H2O mixture at 450 degrees C over the Pd/Al2O3 sample, while the decrease was only from 88% to 60% when catalyst was exposed to CH4-O-2-H2O-NO mixture. We propose that the reason is that the NO reacts with the hydroxyl species to form HNO2, which reduces the water deactivation effect.
46.	Salam, Muhammad Abdus, 1983, et al. (author) Influence of bio-oil phospholipid on the hydrodeoxygenation activity of NiMoS/Al2O3 catalyst 2018 In: Catalysts. - : MDPI AG. - 2073-4344. ; 8:10 Journal article (peer-reviewed)abstract Hydrodeoxygenation (HDO) activity of a typical hydrotreating catalyst, sulfided NiMo/γ-Al2O3for deoxygenation of a fatty acid has been explored in a batch reactor at 54 bar and 320°C in the presence of contaminants, like phospholipids, which are known to be present in renewable feeds. Oleic acid was used for the investigation. Freshly sulfided catalyst showed a high degree of deoxygenation activity; products were predominantly composed of alkanes (C17 and C18). Experiments with a major phospholipid showed that activity for C17 was greatly reduced while activity to C18 was not altered significantly in the studied conditions. Characterization of the spent catalyst revealed the formation of aluminum phosphate (AlPO4), which affects the active phase dispersion, blocks the active sites, and causes pore blockage. In addition, choline, formed from the decomposition of phospholipid, partially contributes to the observed deactivation. Furthermore, a direct correlation was observed in the accumulation of coke on the catalyst and the amount of phospholipid introduced in the feed. We therefore propose that the reason for the increased deactivation is due to the dual effects of an irreversible change in phase to aluminum phosphate and the formation of choline.
47.	Salam, Muhammad Abdus, 1983, et al. (author) NiMoS on alumina-USY zeolites for hydrotreating lignin dimers: Effect of support acidity and cleavage of C-C bonds 2019 In: Sustainable Energy and Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 4:1, s. 149-163 Journal article (peer-reviewed)abstract NiMoS on alumina, USY and mixed alumina-USY supports was studied in a batch reactor to assess the effect of support acidity in valorizing lignin dimers by hydrodeoxygenation (HDO). The reactivity of α-O-4 (benzyl phenyl ether), β-O-4 (2-phenethyl phenyl ether) and 5-5′ (2,2′-dihydroxybiphenyl) linkages was investigated in dodecane at 593 K and a H2 pressure of 5 MPa. A relatively fast rate of hydrogenolysis of the sp3 hybridized etheric bonds was observed for the catalyst supported on the mixed support. With the α-O-4 linkage, the USY supported catalyst selectively yielded deoxygenated aromatics including BTX products with fewer residual C-C dimers. For the β-O-4 linkage, analogous trends have been observed but with more aromatics. Interestingly, with 5-5′ linkages the catalyst on USY and mixed supports can break the C-C linkages without producing other intermediate C-C dimer byproducts. The results show high hydrocracking and isomerization activities of the catalyst supported on USY and mixed supports. This is consistent with XRD, Raman, XPS and TEM measurements, where enhanced dispersion of the active phase was observed. However, hydrogenation activity on the USY support is reduced to a significant degree which results in a large amount of benzene compared to NiMoS-Al2O3 that produces mostly cyclohexane. In addition, elemental analysis revealed that carbon deposition is higher on the USY-based catalyst compared to the alumina-based catalyst owing to its higher acidity. However, the potential for superior C-C bond cleavage on NiMoS-USY opens the possibility to valorize technical lignin in biorefinery processes.
48.	Say, Zafer, et al. (author) Sulfur-tolerant BaO/ZrO2/TiO2/Al2O3 quaternary mixed oxides for deNOX catalysis 2017 In: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 7:1, s. 133-144 Journal article (peer-reviewed)abstract Advanced quaternary mixed oxide materials in the form of BaO/Al2O3/ZrO2/TiO2 functionalized with Pt active sites (i.e. Pt/BaO/AZT) were synthesized and structurally characterized via XRD and BET in comparison to a conventional Pt/20BaO/Al benchmark NSR/LNT catalyst. The interactions of these catalysts' surfaces with SOx and NOx gases were monitored via in situ FTIR and TPD. There exists a delicate trade-off between NOx storage capacity (NSC) and sulfur uptake/poisoning which is strongly governed by the BaO loading/dispersion as well as the surface structure and acidity of the support material. Flow reactor measurements performed under realistic catalytic conditions show the high NOx activity for the Pt/20BaO/AZT catalyst at 573 K. After sulfur poisoning and subsequent regeneration at 773 and 973 K, Pt/20BaO/AZT surpassed the NOx catalytic performance at 573 K of all other investigated materials including the conventional Pt/20BaO/Al benchmark catalyst. © The Royal Society of Chemistry 2017.
49.	Say, Zafer, et al. (author) Trade-off between NOx storage capacity and sulfur tolerance on Al2O3/ZrO2/TiO2–based DeNOx catalysts 2019 In: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 320, s. 152-164 Journal article (peer-reviewed)abstract Al2O3/ZrO2/TiO2 (AZT) ternary mixed oxides functionalized with Pt and BaO were synthesized in powder and monolithic forms and were utilized in NOx Storage Reduction/Lean NOx Trap (NSR/LNT) catalysis as novel catalytic materials. Adsorption of NOx and SOx species and their interactions with the catalyst surfaces were systematically investigated via in-situ FTIR technique revealing different NOx coordination geometries governed by the presence and the loading of BaO in the powder catalyst formulation. While BaO-free Pt/AZT stored NOx as surface nitrates, BaO incorporation also led to the formation of bulk-like ionic nitrate species. NOx adsorption results obtained from the current Temperature Programmed Desorption (TPD) data indicated that NOx Storage Capacity (NSC) was enhanced due to BaO incorporation into the powder catalyst and NSC was found to increase in the following order: Pt/AZT < Pt/8BaO/AZT < Pt/20BaO/Al2O3 < Pt/20BaO/AZT. Increase in the NSC with increasing BaO loading was found to be at the expense of the formation of bulk-like sulfates after SOx exposures. These bulk-like sulfates were observed to require higher temperatures for complete regeneration with H2(g). Catalytic activity results at 473 K and 573 K obtained via flow reactor tests with monolithic catalysts suggested that Pt/AZT and Pt/8BaO/AZT catalysts with stronger surface acidity also revealed higher resistance against sulfur poisoning and superior SOx regeneration in spite of their relatively lower NSC. Monolithic Pt/20BaO/AZT catalyst revealed superior NSC with respect to the conventional Pt/20BaO/Al2O3 benchmark catalyst at 573 K after sulfur regeneration. On the other hand, this trend was reversed at high-temperatures (i.e. 673 K). Preliminary results were presented demonstrating the enhancement of the high-temperature NSC of AZT-based materials by exploiting multiple NOx-storage components where BaO functioned as the low/mid-temperature NOx-storage domain and K2O served as the high-temperature NOx storage domain. Enhancement in the high-temperature NOx-storage in the BaO-K2O multiple storage domain systems was attributed to the formation of additional thermally stable bulk-like nitrates upon K2O incorporation.
50.	Shrestha, S., et al. (author) Selective ammonia oxidation on multi-layer Cu-SSZ-13/Pt/Al2O3 Monoliths: Impact of top layer 2015 In: Catalysis and Reaction Engineering Division. ; 1:2015, s. 527-530 Conference paper (peer-reviewed)

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