Intensifying Ethylene and Propylene of Pentene Cracking of FCC Gasoline by Modulating the Brønsted Acid Site Concentrations
Hailing Sun, Binrui Zhang, Chenhao Wei, Liyuan Cao, Yuhao Zhang, Liang Zhao, Jinsen Gao, Chunming Xu
Abstract
To reveal the effects of Brønsted acid site concentrations on product distribution and reaction pathways of pentene cracking, ZSM-5 zeolites with similar pore structures and different acid concentrations were prepared and evaluated using C5 distillate of FCC gasoline as feed. Three indexes related to reaction pathways (M/B, P/O, and A/O) were defined. A high strong Brønsted acid sites (SBAS) concentration favored the increase in the M/B index to promote monomolecular cracking pathways. However, the P/O index and the A/O index also increased, resulting from the enhancement of the hydrogen transfer reaction and aromatization. Therefore, an intermediate concentration of SBAS was advantageous to produce more ethylene and propylene. The optimum concentration range of SBAS was 4.4–6.7 μmol·g–1 for the maximum total yield of ethylene and propylene (74.7 wt %). The indexes (M/B, P/O, and A/O) provided a new thought to optimize the design of catalysts for intensifying ethylene and propylene by controlling the olefin cracking reaction pathways.