Spent fluid catalytic cracking catalyst derived MCM-41 supported polyethylenimine for post-combustion CO2 capture

Abstract

The buildup of solid waste as well as the global warming has become one of the major challenges. CO2 capture with solid amine synthesized from solid waste can not only address the issue of large CO2 emissions, but also achieve efficient utilization of solid waste. In this work, spent fluid catalytic cracking catalysts (sFCCc), a type of major wastes in petrochemical industries, are first utilized to synthesize polyethyleneimine (PEI) functionalized ordered mesoporous materials. The as-obtained MCM-41-PEI from sFCCc exhibits an acceptable equilibrium CO2 capacity (qe) of 2.7 mmol/g in simulated flue gases (10 % CO2/N2) at 65 °C, which is higher than one prepared with commercial silicon source. Moreover, the adsorbent displays excellent cyclic stability during 50 TSA cycles in the dry simulated flue gases, where the capacity decreases only by 4.9 %. Additionally, the breakthrough capacity (qb) is significantly improved from 0.6 mmol/g to 1.6 mmol/g under humid conditions (35 °C, 10 % CO2/N2). Interestingly, we discover that the optimal adsorption temperature of MCM-41-PEI with different PEI loadings shifted due to the distinct PEI distribution behavior within the pores. The Avrami model provides a reliable interpretation for the CO2 adsorption behavior of MCM-41-PEI at various test conditions. The synthetic strategy here provides a new route in the treatment of excessive sFCCc resources to achieve valuable adsorbents, which can be applied to dilute source CO2 capture processes.