The characteristic studies, by means of LR, UV-Vis and XPS spectroscopies, of the preparation process of Mo-Co-S and Mo-Fe-S catalysts for HDS and HDN, derived from (NH4)2MoS4-CoCl2 and (NH4)2MoS4-FeCl2 complexes supp...The characteristic studies, by means of LR, UV-Vis and XPS spectroscopies, of the preparation process of Mo-Co-S and Mo-Fe-S catalysts for HDS and HDN, derived from (NH4)2MoS4-CoCl2 and (NH4)2MoS4-FeCl2 complexes supported on γ-Al2O3, respectively, indicate that the catalytically essential moiety on the surface of the catalysts is dominantly some sulfido-bimetallic species with such a structural unit (M' =Co or Fe), and both Co and Fe, served as promoters, can donate electrons to Mo probably via bridging-S. The nature of active-sites and the mechanism of promotion are discussed according to the results.展开更多
With home-made multi-walled carbon nanotubes （MWCNTs, simplified as CNTs in later text） as support, CNT-supported Co-Mo-S catalysts, denoted as x%（mass percentage）MoiCoj/CNTs, were prepared. Their catalytic perfor...With home-made multi-walled carbon nanotubes （MWCNTs, simplified as CNTs in later text） as support, CNT-supported Co-Mo-S catalysts, denoted as x%（mass percentage）MoiCoj/CNTs, were prepared. Their catalytic performance for thiophene hydrodesulfurization （HDS） and pyrrole hydrodenitrification （HDN） reactions was studied, and compared with the reference system sup- ported by AC. Over the 7.24%Mo3Co1/CNTs catalyst at reaction condition of 1.5 MPa, 613 K, C4H4S/H2=3.7/96.3（molar ratio） and GHSV≈8000 mlswP/（g-cat.h）, the specific HDS activity of thiophene reached 3.29 mmolc4H4S/（s.molMo）, which was 1.32 times as high as that （2.49 mmolc4H4S/（s.molMo）） of the AC-based counterpart, and was 2.47 times as high as that （1.33 mmolc4H4S/（s-molMo）） of the catalysts supported by AC with the respective optimal MoaCol-loading amount, 16.90%Mo3Co1/AC. Analogous reaction-chemical behaviours were also observed in the case of pyrrole HDN. It was experimentally found that using the CNTs in place of AC as support of the catalyst caused little change in the apparent activation energy for the thiophene HDS or pyrrole HDN reaction, but led to a significant increase in the concentration of catalytically active Mo-species （Mo^4＋） at the surface of the functioning catalyst. On the other hand, H2-TPD measurements revealed that the CNT-supported catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to about 673 K. This unique feature would help to generate microenvironments with higher stationarystate concentration of active hydrogen-adspecies at the surface of the functioning catalyst. Both factors mentioned above were favorable to increasing the rate of thiophene HDS and pyrrole HDN reactions.展开更多
基金Supported by the National Natural Science Foundation of China
文摘The characteristic studies, by means of LR, UV-Vis and XPS spectroscopies, of the preparation process of Mo-Co-S and Mo-Fe-S catalysts for HDS and HDN, derived from (NH4)2MoS4-CoCl2 and (NH4)2MoS4-FeCl2 complexes supported on γ-Al2O3, respectively, indicate that the catalytically essential moiety on the surface of the catalysts is dominantly some sulfido-bimetallic species with such a structural unit (M' =Co or Fe), and both Co and Fe, served as promoters, can donate electrons to Mo probably via bridging-S. The nature of active-sites and the mechanism of promotion are discussed according to the results.
基金Supported by National Natural Science Foundation of China (No. 20473063 and No. 20590364).
文摘With home-made multi-walled carbon nanotubes （MWCNTs, simplified as CNTs in later text） as support, CNT-supported Co-Mo-S catalysts, denoted as x%（mass percentage）MoiCoj/CNTs, were prepared. Their catalytic performance for thiophene hydrodesulfurization （HDS） and pyrrole hydrodenitrification （HDN） reactions was studied, and compared with the reference system sup- ported by AC. Over the 7.24%Mo3Co1/CNTs catalyst at reaction condition of 1.5 MPa, 613 K, C4H4S/H2=3.7/96.3（molar ratio） and GHSV≈8000 mlswP/（g-cat.h）, the specific HDS activity of thiophene reached 3.29 mmolc4H4S/（s.molMo）, which was 1.32 times as high as that （2.49 mmolc4H4S/（s.molMo）） of the AC-based counterpart, and was 2.47 times as high as that （1.33 mmolc4H4S/（s-molMo）） of the catalysts supported by AC with the respective optimal MoaCol-loading amount, 16.90%Mo3Co1/AC. Analogous reaction-chemical behaviours were also observed in the case of pyrrole HDN. It was experimentally found that using the CNTs in place of AC as support of the catalyst caused little change in the apparent activation energy for the thiophene HDS or pyrrole HDN reaction, but led to a significant increase in the concentration of catalytically active Mo-species （Mo^4＋） at the surface of the functioning catalyst. On the other hand, H2-TPD measurements revealed that the CNT-supported catalyst could reversibly adsorb a greater amount of hydrogen under atmospheric pressure at temperatures ranging from room temperature to about 673 K. This unique feature would help to generate microenvironments with higher stationarystate concentration of active hydrogen-adspecies at the surface of the functioning catalyst. Both factors mentioned above were favorable to increasing the rate of thiophene HDS and pyrrole HDN reactions.
