Direct Solid Lewis Acid Catalyzed Wood Liquefaction into Lactic Acid: Kinetic Evidences that Wood Pretreatment Might Not be a Prerequisite

The objective of the present work was to determine if wood sawdust can be used instead of isolated cellulose in the general solid‐acid‐catalyzed production of chemicals. The kinetics of model cellulose and pine‐wood sawdust liquefaction into lactic acid were determined in the presence of a solid Lewis acid, ZrW. The catalytic hydrolysis of pine wood was performed at 190 °C in a large‐scale batch reactor (2.5 L). Similar kinetic curves of lactic formation were obtained for cellulose and wood as substrates. Moreover, the initial lactic acid production rate of pine‐wood sawdust was higher than that of model cellulose, proving that, in spite of the presence of lignin/hemicellulose, the catalyst drives the transformation towards lactic acid formation. However, our results give also evidence of solid‐catalyst deactivation for both cellulose and wood substrates. This result indicates that if wood pretreatment can be bypassed, the bottleneck will be the solid‐catalyst regeneration and recycling.