Utilization of ZSM-5/MCM-41 composite as FCC catalyst additive for enhancing propylene yield from VGO cracking

• Published in: Journal of porous materials Vol. 19; no. 4; pp. 499 - 509
• Main Authors: Jermy, B. R., Siddiqui, M. A. B., Aitani, A. M., Saeed, M. R., Al-Khattaf, S.
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01-08-2012; Springer Nature B.V
• Subjects: Additives; Catalysis; Catalysts; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Fracture mechanics; Gasoline; Molecular sieves; Physical Chemistry; Porous materials; Propylene; Transport; Propylene; Light olefins; Composite molecular sieve; Gasoline; ZSM-5; MCM-41; FCC additive; Catalytic cracking
• ISSN: 1380-2224; 1573-4854
• DOI: 10.1007/s10934-011-9499-0

A micro-mesoporous ZSM-5/MCM-41 composite molecular sieve (ZM13) was synthesized and tested as an FCC catalyst additive to enhance the yield of propylene from catalytic cracking of vacuum gas oil (VGO). The catalytic performance of the additive was assessed using a commercial equilibrium USY FCC catalyst (E-Cat) in a fixed-bed micro-activity test unit (MAT) at 520 °C and various catalyst/oil ratios. MCM-41, ZSM-5 and two ZSM-5/MCM-41 composites were systematically characterized by complementary techniques such as XRD, BET, FTIR and SEM. The characterization results showed that the composites contained secondary building unit with different textural properties compared to pure ZSM-5 and MCM-41. MAT results showed that the VGO cracking activity of E-Cat did not decrease by using these additives. The highest propylene yield of 12.2 wt% was achieved over steamed ZSM-5/MCM-41 composite additive (ZM13) compared with 8.6 wt% over conventional ZSM-5 additive at similar gasoline yield penalty. The enhanced production of propylene over composite additive was attributed to its mesopores that suppressed secondary and hydrogen transfer reactions and offered easier transport and accessibility to active sites. Gasoline quality was improved by the use of all additives except MCM-41, as octane rating increased by 6–12 numbers.