The role of metal-support interactions in sintering and themal deactivation of HDS/HDN catalysts

摘要

The sintering process in CoO-MoO_3/Al_2O_3 and NiO-MoO_3/Al_2O_3 catalysts for HDS/HDN has been studied using two industrial catalysts and their model systems, subjected to thermal treatment in oxidizing and reducing atmospheres. The critical role of oxidizing atmosphere for rapid sintering has been found to be connected with the formation of free MoO_3 phase, distinguished by high mobility in lower temperature regime and intermediary presence of liquid phase at higher temperatures. A prerequisite for HDS/HDN catalyst sintering during regeneration is the destruction of active mon-olayer structure that results in formation of the precursor of MoO_3 phase. Specific role of metal-support interactions in this deactivation mechanism has been shown by comparative investigation on model systems prepared on more inert supports (α-Al_2O_3 and SiO_2).