Integrated biorefinery incorporating the one-pot production of esters, monophenols, and alkoxysilanes

An integrated biorefinery will transition towards a comprehensive refining and zero-waste utilization process of all the biomass components, including the largely wasted or ignored inorganics. Here, we report an effective process of combined valorization of both organic components and inorganics. Small molecules from carbohydrates (32.5 wt%) and lignin (22.5 wt%) were obtained under catalyst-free conditions, in addition to a large amount of alkoxysilanes (>80 mol%) from silicon in rice straw. The connection of silicon with other components in rice straw was probed with XPS etching, SEM mapping, and CP/MAS 29Si NMR, etc. Pretreatment of rice straw with physical, chemical, and biological methods helps us reveal the plant's active silicon. It was indicated that both organosilicon connected with organic components in rice straw and the inorganic silica deposited in silica cell exists in rice straw can be converted to alkoxysilanes. Furthermore, exogenous silica could be converted to alkoxysilanes directly when mixed with biomass, indicating a new conversion process. We also demonstrate efficient methods for separating and purifying alkoxysilane and recycling the solvent. An ex-ante life-cycle assessment of the processes has been established. The ex-ante LCA supports the economic viability and predicts minimized waste and clean production of the new process.