An Environment Friendly Approach: Use of Spent FCC Catalyst for Carbonation Reactions

Abstract

In refineries, the FCC unit for the production of gasoline uses large amount of heterogeneous catalysts. The activity of catalyst decreases with time and hence requires regeneration. At certain point, it is impossible to regenerate a catalyst and often deactivated catalysts are discarded as a solid waste. Considering its quality and quantity, an alternative use of spent FCC catalyst was carried in order to utilize the waste effectively. The spent FCC catalyst, an inexpensive source of alumina and silica source was used as raw material to synthesize zeolite X by hydrothermal method. Various parameters were changed to reach its acceptable level. Those parameters include varying methods, synthesis time, aging and temperature. The prepared catalyst was characterized by BET surface area, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) analysis. This catalyst was used in synthesis of five membered cyclic carbonate and its activity was also compared with commercial NaX which has never been reported previously. The path chosen for the preparation of cyclic carbonate is eco-friendly which not only utilizes the carbon dioxide but also replaces the toxic chemical like phosgene. The conversion of carbon dioxide (CO2), an abundant renewable carbon reagent, into cyclic carbonates is of academic and industrial interest. Cyclic carbonate serves as green solvent and has some outstanding properties such as a high boiling point and low toxicity. An enhanced styrene carbonate yield of 31% was obtained under mild conditions of 120ºC, 5 h and 14 bars CO2 pressure. The influence of various parameters like amount of catalyst, reaction time and temperature were investigated carefully. The heterogeneous catalyst was readily separated after the reaction and reused without affecting the selectivity and yield of the product.