Catalytic desorption performance of CO2-rich amine solution over SO2− 4/TiO2-HZSM-5

Abstract

Amine-based solution absorption method, as the most mature CO₂ capture technology, requires enhancing CO₂ desorption performance while reducing energy consumption in desorption. A series of SO2− 4/TiO₂-HZSM-5 catalysts with different TiO₂ contents were prepared by sol-gel method using HZSM-5 as carrier and used in CO₂ catalytic desorption of N-methyl-diethanolamine and piperazine blended amine solution. Results indicated that catalyst performance can be regulated by changing the loading amount of TiO₂. When the mass ratio of TiO₂ to HZSM-5 was 2/1, the resultant STH(2/1) catalyst had large mesoporous surface area and abundant acidic sites and exhibited excellent catalytic performance. Compared with non-catalytic system, CO₂ desorption amount of the entire desorption increased by 15.38% and relative heat duty decreased by 21.69%. Meanwhile, STH(2/1) exhibited good activity and stability after regeneration cycles and had no impact on CO₂ absorption performance. Larger mesoporous surface area of catalyst facilitated sufficient contact between reactants and acidic sites. Abundant amount of strong acid sites and Brønsted acid sites provided a large amount of H⁺, promoting the decomposition of carbamate and deprotonation of protonated amines. The combined action of mesoporous surface area, strong acid sites and Brønsted acid sites promoted CO₂ desorption. In addition, a possible mechanism for CO₂ desorption catalyzed by SO2− 4/TiO₂-HZSM-5 was proposed.