Research on the process of C₄ olefins to propylene and catalysts

Objective  To develop the process of catalytic cracking of C₄ olefins to propylene and the catalyst preparation technology, the pilot test and industrial side line test are completed.

Methods  The fixed-bed evaluation apparatus was used to investigate the impact of catalyst formulation, modification, and industrial conditions on catalyst activity, selectivity, and stability.

Results  The catalyst with ZSM-5 zeolite as the active component had good activity, selectivity, stability and regeneration performance in the conversion of C₄ olefins to propylene. The introduction of phosphorus did not change the crystal structure of the catalyst, but it reduced the number of acidic sites on the catalyst, and adjusted the molar ratio of B acid and L acid of ZSM-5 zeolite. With the increase of phosphorus loading to 5 wt%, the interaction between phosphorus and aluminum in molecular sieves was gradually strengthened, and phosphorus could interact with framework aluminum and non-framework aluminum.

Conclusions  The conversion rate of C₄ olefins is more than 80%, the selectivity of propylene is 35%-45%, the once-through life of catalyst is more than one month, and the regeneration recovery rate is 95%.