Research Projects

Furfural (FA) serves as an excellent platform chemical for the production of valuable chemicals like Tetrahydrofurfuryl alcohol (THFA). However, the one–pot selective hydrogenation of furfural to THFA under mild operating conditions remains a challenge due to competitive decarbonylation (to furan) and dexoygenation reactions (to ring opened products, methylfuran) which reduce selectivity to THFA. On Pd based catalysts, high THFA yields and selectivity (upto 95%) are reported under mild operating conditions (1 MPa, 30 °C), while Ni and Cu based catalysts require harsher conditions (4 MPa, 150 °C). Most of the studies have however been conducted under batch conditions in liquid phase. Commercial scale up of the technology would require continuous flow vapour phase studies to avoid catalyst separation and leaching problems. Vapour phase hydrogenation of furfural on Pd catalysts at atmospheric conditions and ~ 230 °C leads to high furan and low THFA selectivity (less than 10%). Lower reaction temperatures and higher H2 pressures is likely to reduce decarbonylation and favour hydrogenation, but require active catalysts. In this regard, transition metal bimetallic catalysts have demonstrated enhanced catalyst activity and selectivity via modification of the electronic structure and atomic arrangement at the active site. Preliminary theoretical investigations in our group have revealed addition of Co to Pd lowers ring hydrogenation barriers (favour THFA formation) and also inhibits ring opening and decarbonylation reactions (high C-O and C-C scission barriers). In addition, furfuryl alcohol (an intermediate in THFA formation) is also stabilised on the Pd-Co surface. Oxide supports have been used for furfural hydrogenation as they act as Lewis acid sites for furan ring adsorption. Oxygen vacancy concentration of the support has been shown to significantly alter product distribution for other chemistries, but its effect on product selectivity for furfural hydrogenation is still unexplored. In this work, vapour phase hydrogenation of FA on supported Pd-Co bimetallic catalysts under mild reaction conditions (H2 pressure of 1-2 MPa and 150 - 200 °C) in a lab-scale continuous flow fixed bed reactor will be investigated through a combination of experiments and ab-initio Density Functional Theory (DFT) calculations. The role of different catalyst supports (Al2O3, ZrO2, TiO2) and the effect of varying oxygen vacancy concentration of the support on catalytic performance will be evaluated. Process variables will be optimised to identify the catalyst-support combination with highest THFA selectivity. To explain observed activity trends, Density Functional Theory (DFT) calculations will be performed to evaluate the energetics and mechanism of furfural hydrogenation on the Pd-Co surfaces. Results from this work will pave a way for technological scale up of furfural hydrogenation to THFA.