FCC spent catalyst: a reusable catalyst for efficient esterification to synthesize wax esters, acrylates and plasticizers

Abstract

The disposal of spent fluid catalytic cracking (FCC) catalyst, a hazardous waste material from oil refineries, poses a significant challenge for the refining industry. However, reusing the spent FCC catalyst in other chemical processes not only addresses the disposal issue but also improves the economics for refiners. Herein, we present the direct use of spent FCC catalyst as a highly efficient solid acid catalyst for synthesizing industrially important esters such as ‘wax esters’, acrylates, and plasticizers on a multi-gram scale. Furthermore, the catalyst can be easily recovered from the reaction mixture and reused for up to 5 cycles without a significant decrease in its catalytic activity. Analysis of the used spent FCC catalyst through XRD, FT-IR, BET surface area, and FE-SEM revealed no significant change in catalyst composition or morphology even after multiple catalytic cycles. This process is suitable for sustainable development due to the utilization of industrial waste, its high catalytic efficiency, and its ease of purification. Additionally, DFT calculations indicated that the esterification follows the Langmuir–Hinshelwood mechanism, where both the alcohol and the acid co-adsorb on the catalyst surface prior to their reaction. Moreover, the esterification proceeds via a crucial four-membered transition state resulting in the formation of a new C–O bond.