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This study investigates the effect of biodiesel-derived contaminants on vanadia-based NH 3 -SCR catalysts in heavy-duty exhaust aftertreatment. The aim was to study, not only the effect of single contaminants on the catalyst performance, but also of possible interaction effects between poisons. The effect of six potential catalyst poisons (Na, K, Mg, P, S and Zn) was evaluated using an experimental design and multivariate data analysis. Monolithic V 2 O 5 -WO 3 /TiO 2 catalysts were subjected to accelerated laboratory-scale aging, where the six contaminants were fed simultaneously using a wet impregnation method. In addition to NO x conversion tests, the catalysts were characterized by means of ICP-OES, SEM-EDX, XPS, N 2 physisorption and NH 3 -TPD. The lab-aged samples were compared to fresh and vehicle-aged catalysts. The accelerated aging method showed good reproducibility and gave rise to surface compounds similar to those found in vehicle-aged catalysts. Despite plausible differences regarding penetration depth of the contaminants into the walls of the catalyst, the aging method appears to be an efficient way to point out significant chemical poisons. The model obtained from the experimental design was found to correlate well with the experimental data and can therefore be used to predict effects of the various poisons and poison interactions. Significant effects on the NO x conversion were found for P, S, Na, Mg and K as well as for the interactions P × Na, P × K and S × Na. A poisoning effect was found for Mg, Na, K, P × K, and P × Na, where Na and K exhibited the strongest poisoning effect. The deactivating effect of alkali was lowered in the presence of phosphorus and sulfur, which is explained by the formation of phosphates and sulfates, preventing the interaction of the alkali metals with the vanadia active sites. [ABSTRACT FROM AUTHOR]

We report on a high NO x reduction activity over Ag/Al 2 O 3 catalysts, using hydrogen produced in a fuel reformer. The focus of the study is to evaluate the performance of a hydrocarbon selective catalytic reduction (HC-SCR) catalyst in real conditions. Initially, the catalytic materials for the fuel reformer (Rh/CeO 2 -ZrO 2 ) and the HC-SCR (Ag/Al 2 O 3 ) were evaluated in separate bench-scale reactor setups. These two setups were subsequently joined into an integrated bench-scale reactor setup with the aim to evaluate the influence of the reformate on the HC-SCR activity in a controlled environment. In the final phase of the study a 4 wt.% Ag/Al 2 O 3 catalyst doped with 100 ppm(w) Pt was scaled up and tested in a pilot-scale reactor setup. The pilot-scale reactor setup enabled evaluation of the HC-SCR activity in real exhaust gases generated by a single cylinder engine (genset) together with a hydrogen-rich gas supplied from a fuel reformer. Commercial biodiesel (NExBTL) was used as reducing agent for the HC-SCR as well as fuel in the fuel reformer for both the bench-scale and pilot-scale experiments. This study gives an excellent link between evaluations of the catalytic materials, controlled bench-scale experiments and applied engine experiments, proving a viable concept for lean NO x reduction together with onboard hydrogen production. A NO x conversion of above 70% was reached at temperatures below 250 °C, in bench-scale experiments when hydrogen produced in the fuel reformer is added. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this paper is to study and clarify the role of selected supports (both reducible and non-reducible) on the activity, selectivity and stability of RhPt-based catalyst for diesel reforming. Autothermal reforming (ATR) of low-sulfur diesel (S ∼6ppm, C/H ∼6.43 (w/w)), H2O/C ∼2.5, O2/C ∼0.49, was tested at bench scale to detect differences in activity for catalysts consisting of 1wt% Rh and 1wt% Pt supported on alumina, ceria–zirconia (17.5wt% ceria), silica and titania. Promoters in the form of MgO, Y2O3, La2O3, CeO2 and ZrO2, ranging from 4wt% to 10wt%, were also added onto the supports to detect differences in catalyst activity in terms of diesel conversion, CO2 selectivity, and hydrogen and ethylene production. All metals were added sequentially onto the support by the incipient wetness technique and washcoated on 400cpsi cordierite monolithic carriers with dimensions d =17.8mm, l =30.5mm. The product gas analysis, using FTIR and NDIR, showed that RhPt/CeO2–ZrO2 was found to be most active for ATR of diesel since a fuel conversion close to 98% was obtained. Furthermore, the catalyst activity of the unpromoted samples, in terms of diesel conversion, increased in the following order: RhPt/SiO2

Abstract: The catalytic properties of Pd supported on mixtures of zinc oxide, zinc aluminate, and alumina, prepared from γ-alumina and zinc nitrate, were studied for autothermal reforming (ATR) of dimethyl ether (DME). The performance of the catalysts was tested in a small-scale reactor, using cordierite monoliths as substrate. The catalysts exhibited high activity and generated hydrogen-rich product gases with CO concentrations below 5vol.% in the temperature range between 350 and 450°C (at O2:DME=0.7, H2O:DME=2.5, and GHSV=15000h−1). The highest DME conversion was obtained for a catalyst in which the support comprised mainly ZnAl2O4. Physical mixing of the catalysts with γ-Al2O3 resulted in increased DME conversion but a lowering of the CO2 selectivity. The catalysts were characterized by CO chemisorption, liquid nitrogen adsorption, temperature-programmed desorption of ammonia, temperature-programmed reduction, transmission electron microscopy, and X-ray diffraction. It was found that decreasing surface area and decreasing number of acid sites, caused by thermal treatment during generation of the supports, did not affect the activity negatively. The high CO2 selectivity of the catalysts was correlated with PdZn alloy formation. [Copyright &y& Elsevier]