论文部分内容阅读
本文用ESR方法研究了金属卟啉在石油加氢脱硫催化剂表面的吸附机理。金属卟啉的模型化合物是VO-TPP,加氢脱硫催化剂是Co-Mo-Al_2O_3体系。VO-TPP在催化剂表面吸附时,由于中心VO~(2+)离子相对于表面有两种不同取向,从而可能发生两种不同模式的吸附:中心1吸附和中心2吸附。一般情况下由于催化剂表面化学吸附了供电基团H_2O、OH~-等,只可能发生中心1吸附。催化剂经高温灼烧后,脱除了表面吸附的供电基团,隔绝空气吸附VO-TPP,这时会出现中心2吸附。中心2吸附中卟啉分子与表面的作用比中心1吸附中卟啉分子与表面的作用强。样品暴露空气后,中心2吸附会逐渐转化为中心1吸附。
In this paper, the adsorption mechanism of metalloporphyrin on the surface of petroleum hydrodesulfurization catalyst was studied by ESR method. The model compound of metalloporphyrin is VO-TPP, and the hydrodesulfurization catalyst is Co-Mo-Al 2 O 3 system. When VO-TPP is adsorbed on the catalyst surface, two different modes of adsorption may occur due to two different orientations of the central VO 2+ ions relative to the surface: center 1 adsorption and center 2 adsorption. Under normal circumstances due to the chemical surface of the catalyst chemisorbed the feeding group H_2O, OH ~ - and so on, may only occur in the center 1 adsorption. After the catalyst is burnt at high temperature, the surface of the adsorbed power supply group is removed, and the air is adsorbed to the VO-TPP. At this time, the center 2 is adsorbed. Center 2 adsorption of porphyrin molecules and the role of the surface than the center of a adsorption of porphyrin molecules and the role of the surface. After the sample exposed to air, the center 2 adsorption will gradually transformed into the center 1 adsorption.