Stabilized hierarchical USY zeolitecatalysts for simultaneous increase in diesel and LPG olefinicity during catalytic cracking

Abstract

Hierarchical USY zeolites obtained by scalable and affordable post-synthetic modifications (PSM) are stabilized by means of REO ion exchange and/or hydrothermal treatments, leading to FCC catalysts with improved hydrothermal stability, increased bottoms conversion capacity and improved product selectivity, as compared to a conventional commercial USY based catalyst of comparable activity. The stabilized mesoporous USY yields more and better quality diesel with a reduced content of polyaromatic compounds, while producing lower amounts of gases but with a LPG fraction enriched in propene and butenes. The obtained selectivity slate is attributed to the combination of appropriate Brønsted acidity and reduced diffusion pathway in the zeolite crystals. A detailed characterization relates the physico-chemical, textural and morphological changes induced by the PSM to the resulting catalytic behavior.