Aqueous-Phase Glycerol Catalysis and Kinetics with in Situ Hydrogen Formation

Abstract

Hydrodeoxygenation (HDO) is a widely used technology to convert biomass-based feedstock into value-added fuels and chemical products that usually require high-pressure hydrogen (H2) to remove excess oxygen in the biomass feedstock. To make this process safer and more sustainable, we investigated glycerol conversion under an inert atmosphere in aqueous media using multimetallic catalysts (comprised of Ru, Re, and Pt) supported on activated carbon. Here we report a trimetallic Ru-Re-Pt catalyst that converts glycerol to value -added products such as 1,2-propanediol (1,2-PDO) and linear alcohols with higher selectivity with in situ formed H2 (without using external H2). Thus, the proposed system eliminates use of expensive hydrogen while giving high selectivity unlike the hydrogenation with external hydrogen. The results of catalyst screening showed high glycerol conversion (83%) with liquid-phase product selectivity of 72% and 1,2-PDO selectivity of 43% at 493 K and autogenous pressure with optimized Ru-Re-Pt/C trimetallic catalyst in the presence of a solid base promoter (MgO). To infer the mechanism of hydrogenation with in situ-formed H2, temporal concentration-time profiles at various operating conditions were elucidated using a kinetic model. Such a model provides valuable mechanistic insights and guidance for developing optimal catalyst formulations for maximizing hydrodeoxygenation products with in situ-formed hydrogen.

Synergistic Bimetallic Pd–Pt/TiO2 Catalysts for Hydrogenolysis of Xylitol with In Situ-Formed H2

“…According to the product distribution (Figure 2) and literature reference, 24,43,44 we proposed reaction pathways (Figure 3 Based on the discussion mentioned above, it can be seen that the presence of bimetallic Pd−Pt nanoparticles is able to catalyze tandem H 2 generation and hydrogenolysis of xylitol; thus, the formation of glycols can be well achieved even in the absence of externally added H 2 .…”

Catalytic Transfer Hydrogenolysis of Glycerol over Heterogeneous Catalysts: A Short Review on Mechanistic Studies

“…Type A : In‐situ hydrogenolysis without using external H‐donors . Extensive studies have been reported in recent years on glycerol hydrogenolysis to 1,2‐PDO using H 2 generated in‐situ [7–8,30a,b] . Very limited efforts have been devoted to this area, because rational design of bifunctional materials to transform glycerol in simultaneous C−O and C−H cleavage is very challenging [5d,9] .…”

Direct Transformation of Glycerol to Propanal using Zirconium Phosphate‐Supported Bimetallic Catalysts

“…[13,14] It is worth noting that highly efficient and selective hydrogenolysis of glycerol to 1,2-PDO has been achieved on various catalytic systems. [7,[15][16][17][18][19][20] Although the dehydration of 1,2-PDO to propanal (PA) has also been studied using various types of heterogeneous catalysts, the catalytic activity and selectivity to PA still remains a huge challenge. [21][22][23][24][25][26] The PA with a reactive formyl group is an important potential intermediate material to produce high value-added chemicals such as rubbers, plastics, paints, and pesticides, which are commercially produced from fossil resources now.…”

“…Among them, one of the most promising approaches is the catalytic hydrogenolysis of glycerol into propanediols, such as 1,3‐propanediol (1,3‐PDO) and 1,2‐propanediol (1,2‐PDO) . It is worth noting that highly efficient and selective hydrogenolysis of glycerol to 1,2‐PDO has been achieved on various catalytic systems …”