还原温度对氧化铝负载的磷化钨催化剂咔唑加氢脱氮活性影响(英）

A series of WP/Al2O3 catalysts with WO3 loading of 30% were prepared by impregnation and reduced in H2 for 4h at different temperatures. The catalysts were characterized by XRD, BET, TG and 31P MASNMR. Over these catalysts, the hydrodenitrogenation (HDN) of carbazole was performed at 633K and 3.0MPa. The results indicated that the active species of WP was accumulated on the support surface at a reduction temperature above 1023K. Only phosphate was detected at the chemical shift of -2.4×10-5 in the catalyst reduced at 923K. WP species was observed at the chemical shift of 2.55×10-4 with low speed of sample rotation in the catalyst reduced at 1073K, while another peak was also detected with the chemical shift of 6.88×10-4 at high speed of sample rotation; this was probably related to a similar structure of —Al—O—W—P owing to the strong interaction of active species with support, which corresponded to the species with the peak at 2θ of 40.44° by XRD. The phosphiding degree of catalyst precursor could be improved by increasing reduction temperature. WP/Al2O3 prepared at 923K exhibited the highest HDN activity with a carbazole HDN conversion of 79%. Three reaction paths of carbazole HDN were derived, which suggested that hydrodenitrogenation was superior to the direct denitrogenation.