Solvent- and Base-Free Oxidation of 5-Hydroxymethylfurfural over a PdO/AlPO4-5 Catalyst under Mild Conditions

Recent Advances in the Synthesis of 2-Furoic Acid and 2,5-Furandicarboxylic Acid from Furfural

2,5-furandicarboxylic acid (FDCA) is an important organic platform compound that has been widely used in the fields of medicine, pesticides, dyes, plastics and resins due to its unique structure and properties. In recent years, with the emphasis on sustainable development and green chemistry, the synthesis of FDCA from biomass has attracted extensive attention. The catalytic conversion of furfural (FF) to FDCA has the advantages of easy availability of the raw material, environmental friendliness, economic feasibility and so on, which is an important direction for FDCA synthesis in the future. This paper mainly reviews the prepare pathways of furoic acid (FA) and FDCA using FF as a starting material, including the selective conversion of FF and FA to target products under different types of catalysts. First, the research progress in the synthesis of FA from FF was summarized, and then the advances in the catalytic conversion of FA to FDCA was reviewed. In addition, the development of efficient and green catalysts and the optimization of existing synthesis protocols are emphasized as key factors to improve the yield and purity of FDCA while reducing production costs. Finally, the opportunities and challenges were discussed.

Recent Advances in Lignocellulose-Based Monomers and Their Polymerization

Replacing fossil-based polymers with renewable bio-based polymers is one of the most promising ways to solve the environmental issues and climate change we human beings are facing. The production of new lignocellulose-based polymers involves five steps, including (1) fractionation of lignocellulose into cellulose, hemicellulose, and lignin; (2) depolymerization of the fractionated cellulose, hemicellulose, and lignin into carbohydrates and aromatic compounds; (3) catalytic or thermal conversion of the depolymerized carbohydrates and aromatic compounds to platform chemicals; (4) further conversion of the platform chemicals to the desired bio-based monomers; (5) polymerization of the above monomers to bio-based polymers by suitable polymerization methods. This review article will focus on the progress of bio-based monomers derived from lignocellulose, in particular the preparation of bio-based monomers from 5-hydroxymethylfurfural (5-HMF) and vanillin, and their polymerization methods. The latest research progress and application scenarios of related bio-based polymeric materials will be also discussed, as well as future trends in bio-based polymers.

Current Advances in the Sustainable Conversion of 5-Hydroxymethylfurfural into 2,5-Furandicarboxylic Acid

2,5-Furandicarboxylic acid (FDCA) is currently considered one of the most relevant bio-sourced building blocks, representing a fully sustainable competitor for terephthalic acid as well as the main component in green polymers such as poly(ethylene 2,5-furandicarboxylate) (PEF). The oxidation of biobased 5-hydroxymethylfurfural (HMF) represents the most straightforward approach to obtain FDCA, thus attracting the attention of both academia and industries, as testified by Avantium with the creation of a new plant expected to produce 5000 tons per year. Several approaches allow the oxidation of HMF to FDCA. Metal-mediated homogeneous and heterogeneous catalysis, metal-free catalysis, electrochemical approaches, light-mediated procedures, as well as biocatalytic processes share the target to achieve FDCA in high yield and mild conditions. This Review aims to give an up-to-date overview of the current developments in the main synthetic pathways to obtain FDCA from HMF, with a specific focus on process sustainability.

Insight into the dehydration of high-concentration fructose to 5-hydroxymethylfurfural in oxygen-containing polar aprotic solvents

A high 5-HMF yield of 85.4% was achieved in polar aprotic oxygen-containing solvent with strong electrophilic maleic acid by quenching DHH.