Role of noble metal catalysts for transformation of bio-based platform molecules

The catalytic hydrogenation has attracted more attention because of straightforward deoxygenation of functionalized bio-based platform molecules to value-added products. This chapter summarizes the concept of noble metal catalysts for conversion of biomass-derived platform molecules such as levulinic acid (LA) and furfural (FFR) to downstream products. Ru metal–supported catalysts showed promising results on efficient conversion of LA with very high γ-valerolactone selectivity in both organic and aqueous solvents. Several factors play an important role in Ru-based catalyst systems for LA hydrogenation, for example, metal particle size, dispersion, and metal to support interaction, which are highlighted in this study. There were several noble metal catalysts (Ru, Pd, Pt, Ir) explored for FFR hydrogenation to achieve products such as furfuryl alcohol, tetrahydrofurfuryl alcohol (THFAL), 2-methyl furan (2-MF), 1,2 pentanediol (1,2 PeDO), cyclopentanone (CPO), and tetrahydrofuran (THF). Ir supported on carbon catalyst showed considerable performance for single-step hydrogenation of FFR with maximum 95% selectivity to 2-MF. The morphological effect of MFI with Pd metal function directs the selectivity to ring and side-chain hydrogenation of FFR to THFAL. Support MMT-K 10 possesses Bronsted acidic sites responsible for C5-O cleavage of furan ring; hence, 3% Pd/MMT-K 10 exhibited excellent catalytic performance by achieving complete FFR conversion and 66% selectivity to 1,2 PeDO. One-pot synthesis of CPO from FFR using 4% Pd/SiO2 gave very high 89% selectivity to CPO with complete FFR conversion. As THF is one of the important products obtained from FFR hydrogenation, process intensification (PI) of FFR hydrogenation to THF also has been addressed. In all these catalytic studies, PI aspects are intended to contribute to a sustainable process for bio-based chemicals.