Waste petroleum fluid catalytic cracking catalysts as a raw material for synthesizing valuable zeolites: A critical overview on potential, applications, and challenges

The fluid catalytic cracking (FCC) process in petroleum refineries produces enormous quantities of waste (spent) catalysts as solid waste. Due to stricter environmental regulations, the safe disposal of spent fluid cracking catalysts (SFCC) is a serious challenge to petroleum refineries. In recent years, the reuse of SFCC as a raw material to prepare valuable aluminosilicate materials (Zeolites) has received much attention since SFCC contains high aluminosilicate precursors (up to 90% w/w) needed to synthesize zeolites. Keeping this in view, in this review, we critically analyzed the potential of SFCC to reuse as a raw material to synthesize various types of zeolites (NaA, NaX, NaY, etc.). Particular attention has been given to different zeolite preparation methods and process parameters that affect the synthesized zeolites' quality, yield, and selectivity. The challenges for the commercialization of SFCC-based zeolites are identified, and the prospective status of research and development of the SFCC into zeolites are explored. Our assessment indicates that the reuse of SFCC to synthesize zeolites is technically feasible and offers exciting opportunities; however, several bottlenecks (purity, lack of scale-up studies, lack of economic feasibility, etc.) need to be addressed to facilitate the development of this process on an industrial scale.