Performance modulation strategies of heterogeneous catalysts for formic acid dehydrogenation: A review

Abstract

Hydrogen has been regarded as a renewable and ideal energy carrier for fossil fuels replacement in the future. However, limitations of hydrogen storage and transportation severely restrict the development of the hydrogen industry. Formic acid (FA), as one of the typical liquid organic hydrogen materials (LOHC), is considered to be a potential material for efficient hydrogen storage. To release the hydrogen stored in FA, an appropriate catalyst is required. Although a number of researches paved the way of formic acid dehydrogenation (FAD) with heterogeneous catalysts, the performances were still unsatisfactory compared with the homogeneous counterparts. From the scientific and economic standpoints, it is necessary to develop the approach of catalytic performance enhancement for the heterogeneous FAD catalysts. In this review, we therefore summarized the performance modulation strategies of FAD with heterogeneous catalysts. The modulation of the heterogeneous FAD catalysts can be conducted on either the active phase or support, which are the essential components of heterogeneous catalysts. In addition to selecting different supports and active phases, they can also be modified to improve the catalytic performance: active phase can be modulated by introducing a second metal (such as Au, Ag, Co, Ni, et al.) to form an alloy or a core-shell structure, while supports can be modified by introducing other elements (such as N, K, O, B, Ca). Furthermore, other strategies such as adding formate, dispersant, and changing solvents were reviewed. This review also provides guidance for further development of heterogeneous FAD catalysts.