Pd/In2O3 modified with ionic liquid catalyzed phenylacetylene carboxylation

The carboxylation of alkynes with CO 2 is a pivotal reaction in organic synthesis. However, the generally poor adsorption and activation of CO 2 in heterogeneous catalytic systems have become a bottleneck problem restricting the efficiency of carboxylation reactions. In this study, we proposed a strategy for modifying heterogeneous catalysts with ionic liquid. By utilizing amino acid ionic liquids to modify the Pd/In 2 O 3 catalyst, the electronic structure of palladium (Pd) nanoparticles is optimized, and the adsorption and activation of CO 2 on the catalyst is enhanced. Additionally, the h-In 2 O 3 support not only regulates the electronic structure of Pd nanoparticles but also provides abundant oxygen vacancies, which facilitates the adsorption of CO 2 in the system. Due to the synergistic catalytic effects of the amino acid ionic liquid and the oxygen vacancies in the h-In 2 O 3 support, the Pd/h-In 2 O 3 -BmimPro catalyst demonstrates a remarkable phenylpropiolic acid yield of 93 % under mild conditions (50 °C, 0.5 MPa). This study provides valuable insights into the application of ionic liquid-modified catalysts in CO 2 conversion technologies. The ionic liquid is loaded on the surface of Pd/In 2 O 3 and commonly catalyzes the carboxylation reaction. • BmimPro modified Pd/h-In 2 O 3 catalyst. After modification, the electronic structure of Pd nanoparticles was optimized. • The CO 2 capture by ILs and the CO 2 activation at oxygen vacancies synergistically enhance the CO 2 conversion efficiency. • The support regulates the electronic structure of Pd, enhancing the adsorption of alkynes. • ILs modification strategies provide new insights for other CO 2 catalytic conversion systems.