Modulation of framework Al distribution and acidity via the combination of hydrothermal treatment and La & P doping for catalytic cracking of n-heptane and diesel

Abstract

Catalytic cracking of light oil to produce the ethylene and propylene has become more attractive. However, the yields of ethylene and propylene remain challenging. Herein, the bifunctional La/P/HT-ZSM-35 zeolite was prepared by the combination of hydrothermal treatment and La & P doping. Compared to La/P/H-ZSM-35 zeolite obtained by direct impregnation method, La/P/HT-ZSM-35 catalysts have higher specific surface area and higher oxide dispersion due to the introduction of La & P interacting with non-framework Al produced by hydrothermal treatment of H-ZSM-35 zeolite. The total yields of ethylene and propylene increased to 57.05%, compared to H-ZSM-35 (31.0%) and La/P/H-ZSM-35 (45.44%), in which the free radical and monomolecular cleavage reactions were promoted in the catalytic cracking process of n-heptane. For real light diesel oil, the overall selectivity of ethylene and propylene was 64.73%, which exhibited excellent generalizability.