Cu nanoparticles-dispersed Mg-Al layered double hydroxides as efficient catalysts for CO2 conversion with propargyl alcohols

Upgrading carbon dioxide (CO 2 ) into valuable products is a highly promising strategy of artificial carbon cycle. In this study, a series of in situ reduced CuMgAl layered double hydroxides (R-CuMgAl-LDHs) composites were synthesized, in which Cu nanoparticles were effectively dispersed and anchored on MgAl-LDHs with formation of Cu + and Cu 0 species. The optimized R-Cu 1.5 Mg 1.5 Al 1 -LDH exhibited excellent catalytic performance for the carboxylative cyclization of 2-methyl-3-butyn-2-ol with CO 2 (turnover number of 243) under mild conditions. The layered structure of LDH stabilized the active Cu species with high dispersion, enhancing the catalytic efficiency of this carboxylative cyclization reaction. Simultaneously, the dual-activation of both CO 2 and propargylic alcohol by Cu 0 /Cu + species generated on the surface of LDH contributed significantly to the catalytic efficiency enhancement. Furthermore, R-Cu 1.5 Mg 1.5 Al 1 -LDH catalyzed the reaction of a wide range of terminal or internal propargyl alcohols with CO 2 , yielding various functionalized α-alkylene cyclic carbonates. Finally, a reasonable reaction mechanism was put forward according to the comprehensive analysis.