New biopolymers based on renewable building blocks from catalytic deoxygenation of hemicelluloses – CATBIOSE

Petroleum resources currently provide the main raw material used in the production of chemicals including synthetic polymers. In addition to the escalating scarcity of these resources, the harmful impact on human health as well as on environment is motivating the scientific community to develop sustainable alternatives for the chemical industry in general and for the polymer production in particular. In this context, renewable building blocks derived from biomass are considered as attractive and inexhaustible resources, if the cultivation of these later ones is well managed. Some of the key renewable raw materials being used to replace petrochemical feedstocks include plant oils, polysaccharides and other plant cell wall components such as lignin or polysaccharides. Hemicelluloses, which represent 15% to 35% of plants and wood and are the second most abundant natural polymers in the vegetal world after cellulose can be considered as a very interesting and underexploited source of bio-based building blocks for the chemistry and polymer industries. Unlike cellulose, hemicelluloses are composed of different 5- and 6-carbon sugars, have a low degree of polymerisation (50-300), present ramification in the main chain molecule, and are essentially amorphous. The most important classes of hemicellulose belong to (galacto)-glucomannans (G-GM) and arabino-xylans (AX). Recent efforts have been undergone to allow extracting hemicelluloses prior Kraft cooking with a minimum of damage to the fibers used in papermaking. However, despite important efforts, a large fraction of the extracted hemicelluloses-rich material is composed of monomers or low-molecular mass oligomers. Alternatives to add value to this low molecular mass fraction are therefore needed. In this project, we propose the development of i) an efficient recovery process for this low-molecular fraction and ii) the production of polyols through catalytic deoxygenation of the sugars; iii) their oxidation into dicarboxylic acids to be used as renewable building blocks for iv) the synthesis of polyesters and polyurethanes, with the main objective to replace petroleum-based counterparts. Based on previous work carried out for other mono/polysaccharides, the project proposes to study the hydrolysis/hydrogenolysis of soluble hemicelluloses/oligomers/monomers in presence of supported metals as catalysts to produce polyols (C2-C6) having different OH groups and their conversion into polymerisable dicarboxylic acids, depending on the reaction conditions. Depending on the number of remaining carbon atoms in the polyols (breakdown of C-C linkages), the number of OH groups (deoxygenation) and the degree of oxidation of OH into COOH groups, totally different polymers (polyesters or polyurethanes) can be obtained. The most promising conditions for hemicelluloses extraction and purification, their catalytic transformation into polyols then to carboxylic acids and polymerization as polyesters or polyurethanes will be optimized and scaled-up in order to produce enough amounts of materials to be tested in some specific applications (composites, insulating panels, cosmetics, etc). The approach will be completed by (simplified) technical, environmental and economic studies compared to other commercially available polyesters and polyurethanes. The project constitutes thus a coherent ensemble, proposing a new, eco-efficient way of producing bio-sourced commodity products. Although fundamental research aspects constitute the core of the project, the consortium gathers cross-disciplinary partners: IRCELYON, specialized in catalysis; LIST, specialized in polymers and materials science and FCBA, technical center for the forest-related industries which is in strong connection with wood, pulp and paper, and chemistry industry. This will undoubtedly guarantee effective transfer of knowledge created during the project to industry.