Formic acid is a main product from biomass-derived carbohydrates and is attracting ever more attention as a sustainable hydrogen source, owing to its high volumetric hydrogen density of 53 g of H2 per liter. In this review, we give an overview of the formic acid mediated transformations of biomass-based feedstocks into added-value products, including biofuels; attention will be primarily focused on the transformation of biomass-derived platform chemicals, with an emphasis on levulinic acid. Formic-acid mediated lignin depolymerization and biomass-oil upgrading will be also discussed.

Formic acid, a biomass-derived source of energy and hydrogen for biomass upgrading

Currently, the development of alternative and green energy sources has been being strongly pushed aiming to recoup the lack of fossil energy, to meet the ever-increasing demand of energy use in modern society, and to palliate concerns regarding environmental pollution and global climate change. Therefore, producing energy from biomass sources has recently been of great interest because biomass is considered as a reliable and ubiquitous source. Indeed, the conversion of biomass into furan derivatives through the catalytic production process is emerging as a fascinating and promising method. Being one of the furan-based compounds, 2-Methylfuran (MF) is known as a critical platform substance and an ideal green solution on the pathway of finding alternative fuels because the MF properties are similar to those of fossil fuels and MF could be generated from renewable biomass source. In this review paper, the process of MF synthesis from biomass through catalyst reactions was thoroughly analyzed. More importantly, the pyrolysis and oxidation progress of MF was also critically presented aiming to clarify the applicability of MF to internal combustion engines. Finally, the performance, the characteristics of combustion, and pollutant formation of internal combustion engines fueled with MF were discussed in detail. In general, MF could become a promising alternative fuel for internal combustion engines although studies on the engine durability, compatibility to materials, tribology behaviors should be further carried out in the future.

2-Methylfuran (MF) as a potential biofuel: A thorough review on the production pathway from biomass, combustion progress, and application in engines

Abstract The ruthenium-catalyzed generation of hydrogen from formic acid was investigated in the presence of amines and halide additives. While amidines and halide additives increase the production of hydrogen with [RuCl 2 ( p -cymene)] 2 , >330 mL hydrogen/h is generated in the presence of [RuCl 2 (benzene)] 2 /dppe and N , N -dimethyl- n -hexylamine.

Improved Hydrogen Generation from Formic Acid

As a natural renewable resource, the catalytic conversion of lignocellulosic biomass is considered to be an important strategy to alleviate the tremendous dependence on fossil resources. The synthesis of γ-valerolactone (GVL), which is hailed as a new-generation of biomass-based platform molecule, is one of the pivotal steps in the transformation of biomass resources into liquid fuels and high-value chemicals. The catalytic routes for the synthesis of GVL from lignocellulosic feedstocks have been continuously enriched and improved in recent years. Herein, our principal focus is the reaction mechanisms and catalytic systems of GVL from various biomass-derived feedstocks. The specific reaction routes and catalytic performances of GVL synthesis based on the traditional basic raw materials such as levulinic acid (LA) and alkyl levulinates (AL) were discussed and compared, and one-pot processes with cascade steps of cellulosic and hemicellulosic derivatives such as furfural (Fur), furfuryl alcohol (FAL) as well as cellulosic carbohydrates into GVL were also summarized and analyzed in detail. A more intuitive and comprehensive retrospection of the up-to-date literatures on GVL synthesis through multiple pathways was presented, and practical suggestions on improving the cost, stability and efficiency of the overall catalytic systems were also proposed.

Jing Feng

Papers

A review about GVL production from lignocellulose: Focusing on the full components utilization

Production of γ-valerolactone from levulinic acid over a Ru/C catalyst using formic acid as the sole hydrogen source.