Bioderived furanic compounds as replacements for BTX in chemical intermediate applications

Abstract

The valorization of sugars and cellulose into high value-added compounds represents a promising alternative to petrochemical processes to produce biobased chemicals. This approach can increase sustainability and improve the environmental impact of the chemical industry. The petroleum fraction BTX, composed of benzene, toluene and the isomers of xylene, provides a large variety of bulk chemicals which are used for myriad applications, most notably for polymers and surfactants. The high demand for bioderived products which are carbon neutral has pushed research toward seeking alternative routes to replace BTX-derived compounds at large scale. Much research has been focused on lignin valorization due to its high aromatic content which can release BTX through hydrocracking, but the development of this process is limited by the low theoretical yield of useful aromatics. Cellulose and hemicellulose represent a valid alternative with the potential to synthesize a large variety of new furanic compounds which can replace aryl compounds derived from BTX. 5-HMF and furfural derived from the dehydration of sugars are the key platform chemicals for a large variety of reactions which lead to different intermediate molecules that can replace BTX with molecules that deliver the same performance or even the same molecule. 2,5-Furandicarboxylic acid (FDCA), caprolactam, phthalic anhydride, furan, maleic anhydride and alkylfurans can be derived from these molecules and can substitute petrochemical resins to obtain the resin polyethylene furoate (PEF), nylon 6,6, plasticizers and surfactants. Much research activities have been focused on the development of catalytic pathways for the efficient valorization of these molecules at high yield but few chemical routes are commercially viable. In this paper, the state of the art in obtaining valuable biobased chemical intermediates to replace BTX will be reviewed by analyzing the synthesis of 5-HMF and furfural and their further transformation. Emphasis is given to the process sustainability, chemical challenges, and prospects for future research.