Sustainable production of formic acid from biomass and carbon dioxide

Formic acid (FA) is a versatile molecule with widespread applications in both chemical industries and renewable energy fields. However, the commercial manufacture of FA is still based on non-renewable fossil feedstock, and thus alternative methods to obtain FA from renewable resources are highly desirable and attract significant scientific attentions. Biomass represents the largest carbon resource on Earth, and various strategies including acid hydrolysis, wet oxidation and catalytic oxidation have been developing to transform biomass resources into FA with relatively high yield and selectivity. Meanwhile, carbon dioxide (CO2) as an inexpensive and widely available C1 platform compound, is also a potential resource to produce FA via hydrogenation by different strategies such as chemical, photochemical and electrochemical catalysis. In this review, FA production from biomass resources especially cellulosic biomass will be systematically summarized according to the transformation methods. Following this, recent progresses in the CO2 valorization to generate FA will be generally illustrated. Finally, the catalytic dehydrogenation of FA to generate hydrogen as a clean and renewable energy fuel will be concisely mentioned since it exemplifies the critical role of FA in future energy restructure tactics.