Recent strategies for enhancing the catalytic activity of CO2 hydrogenation to formate/formic acid over Pd-based catalyst

Abstract

The “greenhouse effect” caused by presence of the large amounts of carbon dioxide (CO2) is becoming extremely serious for the environment. Therefore, it is crucial to advance the progress of practical technologies to minimize the CO2 emissions. The catalytic CO2 hydrogenation with hydrogen (H2) to form formic acid/formate over Pd-based catalysts has been considered as an effective technology to deal with environment and CO2 emission issues. In the past decades, increasing efforts have been contributed to these fields and significant achievements have been obtained. In this review, the state-of-the-art of Pd-based heterogenous catalysts for catalytic conversion of CO2 to formate/formic acid is systematically summarized. First, the key factors associated with catalytic performance are discussed including Pd metal dispersion, electron density of Pd metal and acidity of supports. Second, major achievements on the design of efficient Pd nanometal supported on various materials, mainly metal-organic frameworks (MOFs), carbon materials, silica, zeolites and other porous material, are summarized. Third, the successful strategies applied to maximize catalytic activity of CO2 conversion by reducing the particle size of Pd, alloying foreign metal with Pd to change the electron density of Pd, as well as anchoring of functional groups were also highlighted. Special attention has been given to the mechanism of the catalytic reaction. Finally, a brief perspective to the challenges and new directions in the development of innovative catalytic materials to achieve high catalytic activity in CO2 conversion is also proposed, which would be of great interest in realizing carbon-neutrality in near future.