ENVIRONMENTALLY FRIENDLY UTILIZATION OF SPENT FCC CATALYST: AN EFFICIENT SOLID ACID CATALYST FOR FRIEDEL-CRAFTS ALKYLATION REACTION

摘要

Spent fluidized catalytic cracking (FCC) catalyst discarded from petroleum refineries in large volume is composed mainly of thermally stable aluminosilicates and various metal oxides. Utilization of this catalyst for other industrial applications provides a cost-effective and environmentally friendly way of recycling this solid waste, significantly reducing its environmental effects. Friedel-Crafts alkylation, usually catalyzed by Lewis acids in the liquid phase, constitutes a very important class of reactions commonly used in fine chemicals, intermediates, and petrochemical industries. These reactions were traditionally performed in liquid phase using homogeneous acid catalysts like AlCl_3, HF, BF_3, or H_2SO_4. The new environmental legislation pushes for the replacement of all liquid acids by solid acid catalysts that are environmentally benign and that lead to minimal pollution and waste. In the present study we have made an attempt to convert spent FCC catalyst into zeolite X, which is further modified as a Fe-supported catalyst for benzylation of various aromatic substrates such as xylene and toluene. The said catalyst was characterized by powder X-ray diffraction, surface area and acidity measurement, and morphology study. Furthermore, the catalyst could be easily recovered from the reaction mixture and recycled without any significant loss in activity and leaching of the Fe metal. This solid acid catalyst can be used as a potential catalyst for alkylation applications.