Cd/Co-MOFs containing Lewis acid-base sites is used for CO2 chemical fixation and catalysis of Knoevenagel

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2024-04, Vol.687, p.133596, Article 133596
• Main Authors: Cai, Miao, Chen, Xiao-Li, Yan, Rui-Kui, Ren, Jing, Yang, Hua, Cui, Hua-Li, Wang, Ji-Jiang
• Format: Article
• Language: English
• Subjects: cadmium; carbon dioxide; catalysts; catalytic activity; Cd/Co-MOFs; condensation reactions; Cycladdition Reaction CO2; cycloaddition reactions; epoxides; filtration; hydrogen; industrial wastes; Knoevenagel condensation; Lewis acid-base active sites; Lewis acids; Lewis bases; ligands; porous media; pyridines; surface area
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2024.133596

With the continuous increase of CO2 concentration in the atmosphere, many environmental problems and natural disasters have been brought about, so CO2 capture and utilization technology has received extensive attention. Metal-organic frameworks (MOFs) play an important role in the field of CO2 capture due to their high specific surface area, diverse structures and modifiable functions. Herein, two MOFs were designed and synthesized by solvothermal synthesis: {[Cd2(dcpp)(H2O)2]·DMF·2 H2O}n (1), {[Co2(dcpp)(bpy)(H2O)4]·3.5 H2O}n (2) (H4dcpp = (3, 5- dicarboxyphenyl) pyridine, 2, 2′-bipyridine = bpy). MOFs 1 is 3D microporous network structure based on a binuclear cadmium unit and (dcpp)4- ligand. MOF 2 shows 1D lattice chain, which are linked each other by π···π stacking and hydrogen bonding interactions to form a 3D microporous network. TPD experiments show that there are both Lewis acid sites and Lewis base sites in 1–2, which have high catalytic activity for cycloaddition of epoxides and CO2 under mild solvent-free conditions, and has good recyclability and recyclability. Interestingly, 1–2 showed excellent catalytic CO2 conversion ability, and a strong application potential in the field of industrial waste gas purification. In addition, 1–2 can also be used as a highly efficient catalyst for the Knoevenagel reaction. The thermal filtration experiment has proved its heterogeneity. The cyclic experiments show that 1–2 is an efficient, recyclable and stable heterogeneous catalyst. Finally, the mechanism of CO2 cycloaddition and Knoevenagel condensation catalyzed by 1–2 was discussed. [Display omitted] •MOFs 1–2 has good catalytic activity against carbon dioxide and epoxides, based on abundant Lewis acid-base active sites.•MOFs 1–2 also have good catalytic conversion effect in simulated flue system.•MOFs 1–2 can catalyze Knoevenagel condensation efficiently, and has good catalytic effect on benzaldehyde with different substituents.•MOFs 1–2 catalysts in the two catalytic reactions have good stability, recyclability and heterogeneity.