Uniting 3D printing and photo-thermal catalysis to achieve CO2 hydrogenation over cordierite monolithic catalysts

Abstract

CO2 hydrogenation is a highly important reaction, since it reduces the CO2 concentration in air and provides important chemicals. Among the CO2 conversion routes, photo-thermal catalytic CO2 hydrogenation represents a promising technology. However, the design and fabrication of efficient catalyst is significantly crucial, especially a catalyst with high mass transfer and heating efficiencies. Uniting the advantages of 3D printing and photo-thermal catalysis, the customized cordierite monolithic catalyst was prepared successfully in this study, which can achieve a high CO2 hydrogenation activity at a low temperature. The internal relations among macro-structure, light absorption/heat transfer, and catalytic performance was revealed in detail. The results showed that reduction treatment of monolithic catalyst could improve the catalytic performance obviously. This phenomenon was mainly attributed to the changes in the valence states of Co and Cu, and an increase in the number of oxygen vacancies in catalytic coating. With decreasing the size of the transverse and longitudinal pores suitably, the catalytic performance of monolithic catalyst was improved effectively. The main products are CO and CH4 and their highest activities reached 67.42 and 25.5 mmol·g-1·h-1, respectively, at 200 ℃ and the H2/CO2 volume ratio of 4/1. The high catalytic performance was derived from the improvement of light absorption, heat transfer and reactive area, which collectively promote the electron-hole pairs generated on the catalyst surface and accelerate the adsorption and diffusion of reactants on the catalyst surface, respectively.