Clay-Supported Molybdenum-Based Catalysts for Higher Alcohol Synthesis from Syngas

Abstract

A kind of clay-supported K-Co-Mo catalyst was prepared by a sol-gel method combined with incipient wetness impregnation. The catalyst structure was characterized by X-ray diffraction, N2 adsorption-desorption, H2 temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques and its catalytic performance for higher alcohol synthesis from syngas was investigated. The active components has a high dispersion on the clay support surface. The increase of the Mo loading promoted reduction of Mo6+ but had no significant influence on the reduction of Mo4+ and Co2+ species. After reduction, a kind of lower state Moδ+ (1<δ<4) species was observed on the surface. Compared with the unsupported catalyst, the clay supported K-Co-Mo catalysts showed much higher catalytic performance for alcohol formation. The reason can be explained that the supported catalyst have a high active surface area and the mesoporous structure prolonged the residence time of intermediates for alcohol formation to some extent, which promoted the formation of higher alcohols. The high activity of the catalyst reduced at 773 K may be attributed to the high content of Moδ+ (1<δ<4) species on the surface, which was regarded as the active site for the adsorption of nondissociative CO and responsible for the alcohol formation.