Ziyauddin S. Qureshi*¹, Abdullah Aitani¹, M. Abdulbari Siddiqui¹, Abdulkadir Tanimu¹, Aaron C. Akah² Mansour AlHerz²

¹Center for Refining & Advanced Chemicals, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia

²Research & Development Center, Saudi Aramco, Dhahran, Saudi Arabia

* Speaker; E-mail address: zqureshi@kfupm.edu.sa

In this work, we have built a strategy for developing hierarchical zeolite catalysts, by dissolving a series of ZSM-5 zeolites and growing mesoporous silica and alumina on the surface of zeolites in a single-step approach. This resulted in the formation of core micropore zeolites coated with mesoporous silica-alumina shell, giving rise to a hierarchical structure. ZSM-5 zeolites (SiO₂/Al₂O₃ = 80, 30 and 23) were used as the reference zeolites core for the creation of uniform mesoporous silica and/or Al-containing shell using a simple template-directed sol-gel approach using CTAB as template, TEOS and Al₂(SO₄)₃.18 H₂O as silica and alumina source, respectively. The SiO₂/Al₂O₃ of the core-shell catalysts were controlled by varying the TEOS/zeolite and TEOS/aluminum sulfate ratio, and the catalysts properties were extensively studied. The effectiveness of this strategy in the steam catalytic cracking (SCC) of Arab Extra Light (AXL) crude oil to light olefins was investigated in a fixed-bed reactor. The cracking efficiency of parent Z30 zeolite was considerably increased by template-directed sol-gel coating of mesoporous silica-alumina shell on the zeolite framework to form Z30@MSA composite (as shown in Fig. 1). SCC of AXL at 675 °C showed that Z30@MSA was more selective to light olefins in addition to highest AXL crude oil conversion of 71% and C₂⁼ + C₃⁼ yield of 43.1 wt% ^[1].

Fig. 1. Steam catalytic cracking of crude oil.

References

[1] Qureshi, Z.S., Siddiqui, M.A., Tanimu, A. Aitani, A., Akah, A.C., Xu, Q., AlHerz M. J. Anal. Appl. Pyrol., 2022, 166, 105621.