A kinetic model of multi-step furfural hydrogenation over a Pd-TiO2 supported activated carbon catalyst

The multi-step, aqueous phase hydrogenation kinetics of furfural (FUR) to furfuryl alcohol (FA), 2-methylfuran (2MF), tetrahydrofurfuryl alcohol (THFA) and 5-hydroxy-2-pentanone (5H2P) over Pd-TiO2 on an activated carbon catalyst (derived from a monolith structure) was studied (180 degrees C, 2.1 MPa). Titanium addition created a metal?acid functional catalyst and promoted 5H2P synthesis from furfural. A Langmuir-Hinshelwood model with two active sites (a metal site for hydrogenation steps and an acid site for ring opening step) was applied to fit the kinetic data and parameters of the reaction system were obtained using non-linear regression of experimental data. The kinetic model showed an acceptable agreement with the experimental data with R-2 of 0.93-0.96 and concentration residuals (experimental-model) typically <= 5%. Adsorption constants of 2MF and THFA were significantly lower than the adsorption constants of the other three compounds. A reaction rate constant of 1.6-1.8 mol/gcat.h for furfural consumption was predicted by the model. Reaction rates of 0.2-0.35 mol/gcat.h, 0.1-0.13 mol/gcat.h and 0.8-1.0 mol/gcat.h were predicted for formation of 2-methylfuran, tetrahydrofurfuryl alcohol and 5-hydroxy-2-pentanone, respectively. External and internal mass transfer criterion indicate intrinsic rate parameters were estimated and indicate the model can be used to perform monolithic reactor design for aqueous phase hydrogenation of furfural.

Automated summary

The study investigated the aqueous phase hydrogenation kinetics of furfural to various compounds over a Pd-TiO2 catalyst on activated carbon, revealing the role of titanium in creating a metal-acid catalyst and promoting specific compound synthesis. By applying a Langmuir-Hinshelwood model, the kinetic data was fitted to predict reaction rates for different compounds, showing good agreement with the experimental data. The model also provided insights into adsorption constants, as well as intrinsic rate parameters, indicating its potential for reactor design in aqueous phase hydrogenation.