Lignocellulosic Materials for the Production of Biofuels, Biochemicals and Biomaterials and Applications of Lignocellulose-Based Polyurethanes: A Review

The present review is devoted to the description of the state-of-the-art techniques and procedures concerning treatments and modifications of lignocellulosic materials in order to use them as precursors for biomaterials, biochemicals and biofuels, with particular focus on lignin and lignin-based products. Four different main pretreatment types are outlined, i.e., thermal, mechanical, chemical and biological, with special emphasis on the biological action of fungi and bacteria. Therefore, by selecting a determined type of fungi or bacteria, some of the fractions may remain unaltered, while others may be decomposed. In this sense, the possibilities to obtain different final products are massive, depending on the type of microorganism and the biomass selected. Biofuels, biochemicals and biomaterials derived from lignocellulose are extensively described, covering those obtained from the lignocellulose as a whole, but also from the main biopolymers that comprise its structure, i.e., cellulose, hemicellulose and lignin. In addition, special attention has been paid to the formulation of bio-polyurethanes from lignocellulosic materials, focusing more specifically on their applications in the lubricant, adhesive and cushioning material fields. High-performance alternatives to petroleum-derived products have been reported, such as adhesives that substantially exceed the adhesion performance of those commercially available in different surfaces, lubricating greases with tribological behaviour superior to those in lithium and calcium soap and elastomers with excellent static and dynamic performance.

Automated summary

This review provides a comprehensive overview of the latest techniques and procedures for treating and modifying lignocellulosic materials to be used as precursors for biomaterials, biochemicals, and biofuels, with a focus on lignin and lignin-based products. Four main pretreatment types, including thermal, mechanical, chemical, and biological, are discussed, with particular attention given to the biological action of fungi and bacteria. The review highlights the vast possibilities of obtaining different final products depending on the selected microorganism and biomass. It extensively describes biofuels, biochemicals, and biomaterials derived from lignocellulose, covering not only the whole lignocellulosic structure but also the main biopolymers, cellulose, hemicellulose, and lignin. Moreover, the formulation of bio-polyurethanes from lignocellulosic materials is emphasized, especially in their applications in lubricant, adhesive, and cushioning material fields. The review also presents high-performance alternatives to petroleum-derived products such as adhesives, lubricating greases, and elastomers with improved properties.