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- Azis, Muhammad Mufti, 1983, et al.
(författare)
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Microkinetic modeling of H2-assisted NO oxidation over Ag-Al2O3
- 2013
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 221, s. 382-397
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Tidskriftsartikel (refereegranskat)abstract
- A microkinetic model has been assembled to investigate the mechanism for NO oxidation over a monolith-supported Ag–Al2O3 catalyst both in the presence and absence of H2. The effect of H2 examined in the kinetic model was to reduce self inhibiting surface nitrate species on active silver sites. A reduced factorial design of inlet experimental conditions was used to generate transient experimental data. The kinetic model was developed based on a single channel reactor model which accounted for mass and heat transfer between gas and catalyst washcoat as well as mass transport resistance in the washcoat. In general, the modeling results could reproduce the transient experimental data well with correct levels of outlet concentrations and time scales for transient responses. It was found that the effect of increased NO and NO2 inlet concentration had a negative correlation with the NO oxidation conversion, which in the model was considered related to the formation of nitrate surface species. In addition, the model in agreement with experiments, clearly showed that H2 promoted the NO oxidation mainly at low temperature and this effect tended to decrease at elevated temperatures. When H2 was present in the feed, the kinetic model showed that H2 was consumed rapidly in the front part of the monolith. This was also seen in the experiments where in all cases H2 was entirely consumed. The rapid reaction of H2 along with resulting transport limitations indicated that the H2 promotion of the NO oxidation reaction may have been isolated to only a portion of the catalyst.
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- Chaoquan, Hu, 1981, et al.
(författare)
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Catalytic hydrogenation of C=C and C=O in unsaturated fatty acid methyl esters
- 2014
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Ingår i: Catalysis Science and Technology. - : Royal Society of Chemistry (RSC). - 2044-4753 .- 2044-4761. ; 4:8, s. 2427-2444
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Forskningsöversikt (refereegranskat)abstract
- Biodiesel derived from edible and non-edible oils has received much attention as a chemical feedstock or as a raw fuel alternative to the traditional diesel due to its renewability and biodegradability. However, the crude biodiesel containing large amounts of polyunsaturated fatty acid methyl esters (FAMEs) is susceptible to oxidation upon exposure to heat, light, and oxygen. Catalytic hydro-genation of biodiesel has been considered as a feasible and powerful technique to improve the oxidative stability of biodiesel and hence to provide stable raw materials for industrial applications. The catalytic hydrogenation of FAMEs is a complex process but basically consists of hydrogenation of C=C or C=O, depending on the desirable properties of final products. In this review, we summarize recent developments in hydrogenation of C=C and C=O in FAMEs with focus on catalysts, reaction mechanisms, and reactor conditions. The features of hydrogenation of FAMEs are generalized and the opportunities for future research in the field are outlined.
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- Creaser, Derek, 1966, et al.
(författare)
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Kinetic modeling of autothermal reforming of dimethyl ether
- 2010
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 1520-5045 .- 0888-5885. ; 49:20, s. 9712-9719
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Tidskriftsartikel (refereegranskat)abstract
- A global kinetic model was developed for the autothermal reforming of dimethyl ether (DME) over a Pd-Zn/Al2O3 catalyst on a cordierite monolith. A kinetic model consisting of five key overall reactions was found to capture the main features of experimental data. The modeling also accounted for heat transport effects in the reactor that are of importance when coupling the exothermic oxidation reactions with endothermic steam reforming reactions. The modeling confirmed that oxidation reactions dominate near the inlet of the reactor, generating a local hot spot. The heat from oxidation reactions accelerates the reforming reactions. Water adsorption was found to have a weak detrimental influence on the activity. Based on the model, the influence of the reactor scale and oxygen supply by air feed on the performance of the reactor was examined.
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- Creaser, Derek, 1966, et al.
(författare)
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Modeling study of 5 kWe-scale autothermal diesel fuel reformer
- 2011
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Ingår i: Applied Catalysis A: General. - : Elsevier BV. - 1873-3875 .- 0926-860X. ; 404, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- A model was developed that successfully describes key operating features of a 5 kWe-scale autothermal diesel fuel reformer with an engineered monolith-supported Rh based catalyst. The model consisted of a kinetic model comprised of four overall reactions including total oxidation, fuel steam reforming, methane formation via fuel decomposition and the water–gas shift reaction. The model also accounted for heat and mass transport effects that were of importance when coupling the exothermic oxidation reactions with endothermic steam reforming reactions in a full-scale reformer. According to the model, the total oxidation and steam reforming reactions occurred simultaneously, however the heat effects of the oxidation reaction dominated near the reactor inlet resulting in a local hot spot. Transport resistances were found to hinder the rates of the main reactions, especially at higher temperature operating conditions. The model was primarily based on experimental data for a commercial low-sulphur diesel fuel (MK1), however it was found to also reasonably well describe the operation of the reactor with a diesel surrogate (n-tetradecane).
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