A comparative study of PdZSM-5, Pdβ, and PdY in hybrid catalysts for syngas to hydrocarbon conversion

The catalytic conversion of syngas into hydrocarbons over hybrid catalysts consisting of a methanol synthesis catalyst and Pd modified zeolites (PdZSM-5, Pdβ, and PdY) was investigated. The results indicate that the intermediate dehydration step of DME in the syngas to hydrocarbon process mainly occurs on the Bronsted acid sites of the Pd zeolite. The large pores and cavities of Pdβ and PdY promote the formation of C4+ hydrocarbons, which are mainly gasoline-type branched hydrocarbons. Moreover, the large pores and cavities provide enough space for the formation of higher aromatics which are the precursor of coke. The blockage of micropores of the Pd zeolites by hydrocarbon-type coke results in the deactivation of the hybrid catalysts.