High temperature synthesis of nanostructured Ce-SAPO-34 catalyst used in conversion of methanol to light olefins: effect of temperature on physicochemical properties and catalytic performance

摘要

The nanostructured SAPO-34 catalyst was synthesized at different temperatures via high temperature hydrothermal method. The synthesized catalysts at different temperatures were modified by impregnating of 0.5 wt% CeO_2. The structures of the synthesized catalysts were characterized by various methods including XRD, FESEM, EDX, BET and FTIR techniques. The synthesized sample at low temperature and without modification has high crystallinity and maximum surface area. By Ce impregnation, crystallinity and surface area reduced, strongly. According to the XRD and FTIR analysis, Ce interacts with structure and hydroxyl groups of SAPO-34. Effect of Ce modification and crystallization temperature on catalytic performance of the SAPO-34 and Ce-SAPO-34 catalysts was investigated in the methanol to olefins process. The modified catalysts by Ce impregnation have lower methane formation compared to the synthesized sample without modification. The catalyst synthesized at 250 ℃ and modified with 0.5 % CeO_2 showed longer lifetime in methanol to olefins process. The small particle size and Ce addition for this catalyst might be responsible for its improved catalytic performance.