MESOPORE STRUCTURE CONTROLLED CONVERSION AND PRODUCTS SELECTIVITY IN THE DESIGN OF HEAVY OIL CATALYTIC CRACKING CATALYST

摘要

Zeolite Y is a highly versatile molecular sieve, however its micropores with aperture diameter below 1 nm greatly limit its utilization in heavy oil catalytic cracking. Regarding the strategy for the design of heavy oil catalytic cracking catalyst, fast mass transfer of the reactants and products is a crucial factor and accordingly mesopore-structured zeolites attract significant interest. In the last decades, a lot of researches have been dedicated to circumvent the diffusional limitation in microporous zeolitic materials through the preferential removal of certain types of framework atoms, such as dealumination and desilication. In our work, four different types of ultrastable Y zeolite were obtained by the post-treatment of conventional NaY (denoted as USY), alkaline treatment of high silica NaY (denoted as USY_A), Boron-containing NaY (denoted as USY_B) and Iron-containing NaY (denoted as USY_(Fe)), with ammonium exchange and steaming. These mesopore structured materials show obvious better performance compare with the reference.