CuO modified KIT-6 as a high-efficiency catalyst for energy-efficient amine solvent regeneration

Abstract

Chemical absorption using an amine solution is currently the most common and effective CO2 capture technology. However, this method suffers from the high energy consumption for solvent regeneration, which hinders its industrial application. It has been proven that catalytic CO2 desorption technology using solid acid catalysts is a promising way to lower regeneration energy consumption. In this study, three transition metal oxides (CuO, NiO and Fe2O3) modified mesoporous molecular sieve (KIT-6) catalysts were prepared and then utilized to catalyze the regeneration process of a rich CO2 monoethanolamine solution. The findings demonstrated that the four catalysts enhanced the CO2 desorption rate and reduced the relative energy consumption. The relative energy consumptions (%) for the amine solvent regeneration using the prepared catalysts follows the order of: blank test (100) > KIT-6 (79.8) > Fe2O3-KIT-6 (76.5) > NiO-KIT-6 (75.4) > CuO-KIT-6 (66.6). The superior catalytic activity of the CuO-KIT-6 catalyst is attributed to its high Brønsted acid sites and large mesoporous surface area. The cyclic test results revealed that after five cycles of absorption–desorption, the catalytic activity of CuO-KIT-6 was still kept at 93.4%. In addition, a potential CuO-KIT-6 catalyst-based catalytic CO2 desorption mechanism was suggested. This study provides a new idea to design and prepare a high-efficiency catalyst to promote regeneration of the CO2-loaded amine solution, lower the regeneration energy consumption, and ultimately increase the economic viability of the catalytic regeneration method.