STIRRED AND UNSTIRRED LIGNIN SOLVOLYSIS WITH FORMIC ACID IN AQUEOUS OR ETHANOLIC SOLVENTS BY USING 5-L REACTOR

摘要

Work objective: Lignin is a low-cost renewable by-product from paper- and pulp and bio-ethanol production which has a high potential for further development as a raw material. Previously, we have developed a solvolytic conversion process with formic acid as a hydrogen donor where lignin is hydrodeoxygenated in a one-step conversion to low molecular weight bio-oils. The thermal decomposition of formic acid gives active hydrogen species that are more reactive than molecular hydrogen at the same conditions. The resulting product is a bio-oil which is a mixture of monomeric phenols and more hydrogenated products. Ongoing research is addressing the upscaling of the process and testing of the final products. We will report results from lignin solvolysis in a 5-L stirred and unstirred batch reactor. Methodology: Lignin conversion is performed at 320-350 ℃ in aqueous or ethanolic solvents. Different levels of loading in the reactor have been tested under stirred and unstirred conditions. Mass and elemental composition balance data for oil and coke yields relative to the input of lignin and formic acid are determined. Experimental designs are used to systematically explore the relationship between the oil and coke yields and the reaction conditions. Results: Oil yields differ with type of the solvent, stirred condition and operating temperature. Overall, ethanolic solvent together with high level of loading in the reactor result in highest oil yield. More than 40% weight of the lignin can be directly recovered as oil at 320 ℃ by using stirring, regardless of solvent type. The increased oil yield can be because of the efficient stirring and/or higher operating pressure when higher level of the reactor is loaded. Compositional data for the bio-oil will also be presented and discussed in the perspective of identifying value-added products. Multivariate statistical models based on the experimental designs provide equations describing the relationship between the reaction conditions and the oil yields.