Modeling the Lignin Degradation Kinetics in a Ethanol/Formic Acid Solvolysis Approach. Part 2. Validation and Transfer to Variable Conditions

A formal kinetic model treating the depolymerization and hydrodeoxygenation of wheat straw lignin in ethanol with formic acid as hydrogen source developed by Gasson et al [Gasson et al. Ind. Eng. Chem. Res. 2012, S1 (32), 10595-10606] IS validated and its applicability in a continuous stirred tank reactor (CSTR). at varying temperatures between 633 K and 673 K is tested. The fitted formal kinetic rate coefficients are compared and sensitivity and flux analyses are performed Activation energies are estimated for the lumped reactions. The depolymerization to primary products is considerably accelerated when transferring the reaction from batch to a continuous operation. Higher heating rates and continuous feeding Of the hydrogen donor formic acid aid in suppressing both gas and char production. Repolymerization of intermediate phenolic compounds is suppressed, which is suggested to be due to the interaction of intermediate and final products. The evaluation shows that a continuous system can aid in avoiding further gasification and charring of the intermediate products in this one-step lignin depolymerization deoxygenation reaction for the production of a phenol-rich bio-oil.