| 1. |
- Salam, Muhammad Abdus, 1983, et al.
(författare)
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One-pot reductive liquefaction of sawdust to renewables over MoO x -Al 2 O 3 variants: insight into structure-activity relationships
- 2024
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Ingår i: Sustainable Energy and Fuels. - 2398-4902. ; 8:12, s. 2668-2681
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Tidskriftsartikel (refereegranskat)abstract
- Valorization of forest residual products can offer a vital pathway to derive bio-based chemicals and fuel components. Herein, we report the effective and direct conversion of sawdust biomass over a supported Mo-oxide catalyst that results in a dominant fraction of aliphatic/cyclic alkanes and alkylbenzenes with low residual solids. The reductive liquefaction was conducted in an autoclave reactor using a series of MoOx-Al2O3 variants in the range of 340-400 °C with an initial H2 pressure of 35 bar for 4 h. At 340 °C, a correlation between Mo-loadings and reactivity for depolymerization and hydrodeoxygenation was found optimal for a surface density of 3.2 Mo-atoms per nm2 corresponding to 8 wt% Mo-loading. The liquefied fraction showed high selectivity (∼38%) for the formation of cycloalkanes and alkylbenzenes. At higher temperatures (400 °C) enhanced reactivity over the optimal catalyst showed higher cycloalkane and alkylbenzenes formation (∼57%) at a low biomass-to-catalyst feed mass ratio (3 : 1). At a higher ratio (10 : 1), alkylphenols (∼41%) are the leading product fraction followed by cycloalkanes and alkylbenzenes (∼34%) with a high liquefied monomer bio-oil product yield of 39.4 wt%. Catalyst characterization via XRD, Raman, H2-TPR, and XPS analysis revealed that the origin for this reactivity arises from the Mo species formed and stabilized over the support surface. A well dispersed, octahedral, higher fraction of easily reducible Mo-species (Mo5+) was evident over the optimal catalyst which enables enhanced C-O cleavage facilitating the hydrodeoxygenation reaction. Moreover, the solid residue yield could be reduced to below 5 wt% by optimizing the reaction conditions and particle size of the sawdust.
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| 2. |
- Awan, Iqra Zubair, et al.
(författare)
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Composition Effect on the Formation of Oxide Phases by Thermal Decomposition of CuNiM(III) Layered Double Hydroxides with M(III) = Al, Fe
- 2024
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Ingår i: Materials. - 1996-1944. ; 17:1
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Tidskriftsartikel (refereegranskat)abstract
- The thermal decomposition processes of coprecipitated Cu-Ni-Al and Cu-Ni-Fe hydroxides and the formation of the mixed oxide phases were followed by thermogravimetry and derivative thermogravimetry analysis (TG – DTG) and in situ X-ray diffraction (XRD) in a temperature range from 25 to 800 °C. The as-prepared samples exhibited layered double hydroxide (LDH) with a rhombohedral structure for the Ni-richer Al- and Fe-bearing LDHs and a monoclinic structure for the CuAl LDH. Direct precipitation of CuO was also observed for the Cu-richest Fe-bearing samples. After the collapse of the LDHs, dehydration, dehydroxylation, and decarbonation occurred with an overlapping of these events to an extent, depending on the structure and composition, being more pronounced for the Fe-bearing rhombohedral LDHs and the monoclinic LDH. The Fe-bearing amorphous phases showed higher reactivity than the Al-bearing ones toward the crystallization of the mixed oxide phases. This reactivity was improved as the amount of embedded divalent cations increased. Moreover, the influence of copper was effective at a lower content than that of nickel.
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| 3. |
- Ho, Hoang Phuoc, 1983, et al.
(författare)
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Effect of the Preparation Methods on the Physicochemical Properties of Indium-Based Catalysts and Their Catalytic Performance for CO 2 Hydrogenation to Methanol
- 2024
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Ingår i: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 38:6, s. 5407-5420
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Tidskriftsartikel (refereegranskat)abstract
- Indium oxides (In2O3) and indium oxides supported zirconia (ZrO2) have been known possible alternatives for conventional copper-based catalysts in the CO2-hydrogenation to methanol. This study aims to investigate the effect of preparation techniques on the physicochemical properties of indium-based materials and their catalytic performance for the hydrogenation of CO2 to methanol. Two series of both single oxide In2O3 and binary In2O3-ZrO2 have been synthesized by combustion, urea hydrolysis, and precipitation with different precipitating agents (sodium carbonate and ammonia/ethanol solution). Physicochemical properties of materials are characterized by elemental analysis, XRD, N2 physisorption, SEM/EDX, micro-Raman, XPS, H2-TPR, and CO2-TPD. Cubic In2O3 was the common phase generated by all four synthesis methods, except for urea hydrolysis, where rhombohedral In2O3 was additionally present. The combustion method produced the materials with the lowest specific surface areas while the precipitation using ammonia/ethanol aided in creating more oxygen defects. The synthesis methods strongly influenced the degree of interaction between the oxides and resulted in improvements in properties that boosted the catalytic performance of the binary oxides compared to their single-oxide counterparts.
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| 4. |
- Le, Ha V., et al.
(författare)
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A sulfonate ligand-defected Zr-based metal-organic framework for the enhanced selective removal of anionic dyes
- 2024
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Ingår i: RSC Advances. - 2046-2069. ; 14:23, s. 16389-16399
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we introduce a novel defective analogue of the representative 6-connected zirconium-based metal-organic framework (MOF-808), by employing 5-sulfoisophthalic acid monosodium salt (H2BTC-SO3Na) as a defect inducer via a mixed-linker approach. The structural integrity and different physicochemical properties were investigated by various characterization techniques, including powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and nitrogen physisorption at 77 K. Additionally, proton nuclear magnetic resonance (1H-NMR), energy-dispersive X-ray (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES) were employed to confirm the presence of 6.9 mol% of the 5-sulfoisophthalate ligand within the highly crystalline MOF-808 structure. The defective material exhibited significant enhancements in the removal efficiency of various organic dyes, including approximately 64% and 77% for quinoline yellow and sunset yellow, and 56% and 13% for rhodamine B and malachite green, compared to its pristine counterpart. Importantly, the defective MOF-808 showed a remarkable selectivity toward anionic species in binary-component dyes comprising both anionic and cationic dyes.
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| 5. |
- Leventaki, Emmanouela, 1996, et al.
(författare)
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Aqueous mineral carbonation of three different industrial steel slags: Absorption capacities and product characterization
- 2024
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Ingår i: Environmental Research. - 0013-9351 .- 1096-0953. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- Heavy carbon industries produce solid side stream materials that contain inorganic chemicals like Ca, Na, or Mg, and other metals such as Fe or Al. These inorganic compounds usually react efficiently with CO2 to form stable carbonates. Therefore, using these side streams instead of virgin chemicals to capture CO2 is an appealing approach to reduce CO2 emissions. Herein, we performed an experimental study of the mineral carbonation potential of three industrial steel slags via aqueous, direct carbonation. To this end, we studied the absorption capacities, reaction yields, and physicochemical characteristics of the carbonated samples. The absorption capacities and the reaction yields were analyzed through experiments carried out in a reactor specifically designed to work without external stirring. As for the physicochemical characterization, we used solid-state Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Using this reactor, the absorption capacities were between 5.8 and 35.3 g/L and reaction yields were in the range of 81–211 kg CO2/ton of slag. The physicochemical characterization of the solid products with solid FTIR, XRD and SEM indicated the presence of CaCO3. This suggests that there is potential to use the carbonated products in commercial applications.
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| 6. |
- Olsson Månsson, Emma, 1992, et al.
(författare)
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Removal of Inorganic Impurities in the Fast Pyrolysis Bio-oil Using Sorbents at Ambient Temperature
- 2024
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Ingår i: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 38:1, s. 414-4254
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Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis bio-oil (FPBO) sourced from residual biomass waste (such as sawdust) is a promising feedstock that may be used for biofuel production. Their inorganic elements may, however, vary and cause deactivation of the catalysts in the hydrodeoxygenation (HDO) upgrading biorefinery unit. It was found that the use of zeolite Y and strong acidic ion-exchange resins as adsorbents was almost equally efficient in lowering the concentrations of Ca from <10 to <1 ppm and of Fe, K, and Mg to <0.3 ppm in FPBO at 30 °C, atmospheric pressure, and 4 h adsorption time. The removal efficiency of zeolite and resins exceeded 85–98% (detection limit) of these particular elements. For the first time for the FPBO, phosphorus was reported as being successfully targeted by aluminum oxide, being lowered from 1 ppm to <0.1 ppm, which is a reduction of at least 90%. Characterization of the oil and sorbents suggests that the surface acidity affects the removal efficiency of these elements from FPBO. Organic compounds in the pyrolysis oil, including isopropanol, lactic acid, hydroxy acetone, furfural, guaiacol, and levoglucosan, were semiquantified using two-dimensional gas chromatography coupled with mass spectrometry (GCxGC-MS). Compared to the fresh oil, the compositions and contents of these organic compounds were not impacted significantly by the sorbents under these mild operating conditions. This research indicates that inorganic impurities present in bio-oils can be removed, and thus, they may be considered feedstocks for producing biofuels with less deactivation of HDO catalysts.
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| 7. |
- Shao, Jieling, 1993, et al.
(författare)
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Pt-based catalysts for NOx reduction from H2 combustion engines
- 2024
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Ingår i: Catalysis Science and Technology. - 2044-4753 .- 2044-4761. ; 14:11, s. 3219-3234
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Tidskriftsartikel (refereegranskat)abstract
- Platinum supported on SSZ-13 zeolite has been found to be a potential catalyst for the selective catalytic reduction of NO by H-2. This work has studied the effects of the H-2/NO molar feed ratios (0/4.4/8.8/13.2) and the impact of water on the performance of the H-2-SCR of NO on the Pt/SSZ-13 catalyst. A higher H-2/NO ratio promoted the start of the reaction at lower temperatures and favoured the production of N-2. The effect of Pt loadings was also studied with three loadings of 0.5/1.0/2.0 wt%. It was found that the 0.5 wt% Pt sample displayed the highest N-2 selectivity of 75%. In addition, an inhibiting effect of water for H-2-SCR at low temperatures was proved. Pt/SSZ-13 has shown good hydrothermal durability after 6 h in total ageing pretreatment at 800 degrees C and interestingly the nitrogen formation even increased. The support effect of SSZ-13, BETA and Al2O3 on H-2-SCR was evaluated in terms of catalytic performance and their catalytic durabilities by hydrothermal ageing experiments, showing that zeolites are significantly better for H-2 SCR. In situ DRIFT measurements helped to explore the mechanism of H-2-SCR on the Pt catalyst. A careful design of the measurements was used to distinguish the overlapping peaks of the water on the DRIFT spectrum. NH4+ ions are formed and it was shown that they play a role as intermediates during the reaction to assist the NO reduction.
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| 8. |
- Yao, Dawei, 1991, et al.
(författare)
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Deciphering SO2 poisoning mechanisms for passive NOx adsorption: A kinetic modeling approach and development of a high-resistance catalyst
- 2024
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Ingår i: Chemical Engineering Journal. - 1385-8947. ; 487
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Tidskriftsartikel (refereegranskat)abstract
- Passive NOx adsorption (PNA) is a promising technology aimed at reducing NOx emissions from vehicles during the cold start phase of the engine. This work investigated the SO2 poisoning mechanism of PNA through a combination of experimental research and kinetic modeling, leading to the development of a novel PNA sample with high resistance to SO2 poisoning. Pd/SSZ-13 samples were synthesized using different drying conditions, revealing that samples dried at room temperature showed lower degradation (10 %) compared to those dried at 80 °C (26 %). Investigation into the degradation revealed that ion-exchanged Pd sites with a hydroxyl group were more resistant to SO2 poisoning than other Pd sites. It is also found that SO2 aids in NOx storage on Pd sites, enhancing the PNA performance. A kinetic model was developed to describe the SO2 poisoning behavior and its influence on NOx storage. The model, which was verified under various conditions, effectively simulated the PNA behavior and SO2 poisoning of Pd/SSZ-13.
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