Ir/ γ Al 2O 3 catalyst for hydrazine decomposition has been investigated by using XPS, SEM, H 2 TPD and H 2 isothermal adsorption. The results show that the iridium species enrich on the surface of the catalyst in mo...Ir/ γ Al 2O 3 catalyst for hydrazine decomposition has been investigated by using XPS, SEM, H 2 TPD and H 2 isothermal adsorption. The results show that the iridium species enrich on the surface of the catalyst in more than one state, and that the metallic iridium is the active sites for the reaction. The iridium species were sintered seriously during the reaction, and the amount of H 2 adsorption on used sample was only a quarter of that on fresh sample. The concentration of Cl - species on the surface decreased quickly at the initial period of the reaction process and stayed at a certain low value. Obvious breakup of the surface structure of the used sample was found. In all, the sintering of metallic iridium and the damage of alumina surface structure are the reasons for deactivation of the catalyst, while the Cl - concentration has little effect on the reaction performance.展开更多
The microcalorimetric technique is employed to study the interaction of NO and NO 2 with the In/HZSM 5 catalyst which has been reported to be active for the selective catalytic reduction (SCR) of NO by CH 4. The amoun...The microcalorimetric technique is employed to study the interaction of NO and NO 2 with the In/HZSM 5 catalyst which has been reported to be active for the selective catalytic reduction (SCR) of NO by CH 4. The amounts of chemisorption and differential heat of NO 2 adsorption on In 2O 3, HZSM 5 and In/HZSM 5 are much larger than those of NO. Furthermore, NO 2 adsorption on In 2O 3 is irreversible. Associating with the results of in situ IR and TPD, and the NO x conversion in NO(NO 2)+CH 4 system over In/HZSM 5 and HZSM 5 catalysts, it is reasonable to propose that in the CH 4 SCR process NO 2 plays a key role, and NO 2 species chemisorbed on the HZSM 5 support can migrate to the In sites to react with CH 4.展开更多
文摘Ir/ γ Al 2O 3 catalyst for hydrazine decomposition has been investigated by using XPS, SEM, H 2 TPD and H 2 isothermal adsorption. The results show that the iridium species enrich on the surface of the catalyst in more than one state, and that the metallic iridium is the active sites for the reaction. The iridium species were sintered seriously during the reaction, and the amount of H 2 adsorption on used sample was only a quarter of that on fresh sample. The concentration of Cl - species on the surface decreased quickly at the initial period of the reaction process and stayed at a certain low value. Obvious breakup of the surface structure of the used sample was found. In all, the sintering of metallic iridium and the damage of alumina surface structure are the reasons for deactivation of the catalyst, while the Cl - concentration has little effect on the reaction performance.
文摘The microcalorimetric technique is employed to study the interaction of NO and NO 2 with the In/HZSM 5 catalyst which has been reported to be active for the selective catalytic reduction (SCR) of NO by CH 4. The amounts of chemisorption and differential heat of NO 2 adsorption on In 2O 3, HZSM 5 and In/HZSM 5 are much larger than those of NO. Furthermore, NO 2 adsorption on In 2O 3 is irreversible. Associating with the results of in situ IR and TPD, and the NO x conversion in NO(NO 2)+CH 4 system over In/HZSM 5 and HZSM 5 catalysts, it is reasonable to propose that in the CH 4 SCR process NO 2 plays a key role, and NO 2 species chemisorbed on the HZSM 5 support can migrate to the In sites to react with CH 4.
