Simultaneous absorption and hydrogenation of CO2 from flue gas by KBH4 catalyzed by nickel nanoparticles supported on TiO2

Considering that the carbon dioxide (CO2) emissions resulting from the combustion of fossil fuels significantly aggravate the global greenhouse effect and frequently lead to extreme environmental problems, it was proposed in this work to carry out the simultaneous capture and resource utilization of CO2 from flue gas by using a low-energy method. Importantly, nickel nanoparticles supported on titanium dioxide (Ni [email protected]2) was prepared to catalyze potassium borohydride (KBH4) to be transformed into BH4-n(OH)n− (n = 0–3) species with strong hydride donation capacity, which hydrogenated CO2 to formate under atmospheric pressure and mild temperature. The optimum experimental conditions for the catalytic hydrogenation of CO2 were determined by investigating the effects of various factors on the CO2 conversion: the Ni [email protected]2 dosage was 1 g·L−1, KBH4 concentration was 0.2 mol·L−1, solution pH was 9.5, reaction temperature was 60 °C and flow velocity of flue gas was 0.5 L·min−1. The average CO2 conversion efficiency was achieved as 51.2% under the optimal conditions. Based on a series of catalyst characterizations, product analyses and related literatures, the catalytic hydrogenation reaction mechanism for the conversion of CO2 to formate was analyzed. This work can provide reference for developing the processes for CO2 emission reduction combined with resource utilization.