Hydrodeoxygenation of Lignin-Based Compounds over Ruthenium Catalysts Based on Sulfonated Porous Aromatic Frameworks

Bifunctional catalysts are a major type of heterogeneous catalytic systems that have been widely investigated for biomass upgrading. In this work, Ru-catalysts based on sulfonated porous aromatic frameworks (PAFs) were used in the hydrodeoxygenation (HDO) of lignin-derived compounds: guaiacol, veratrole, and catechol. The relationship between the activity of metal nanoparticles and the content of acid sites in synthesized catalysts was studied. Herein, their synergy was demonstrated in the Ru-PAF-30-SO3H/5-COD catalyst. The results revealed that this catalytic system promoted partial hydrogenation of lignin-based compounds to ketones without any further transformations. The design of the Ru-PAF-30-SO3H/5-COD catalytic system opens a promising route to the selective conversion of lignin model compounds to cyclohexanone.

DFT study on dibenzofuran conversion to cyclohexane and benzene in gas, water and methanol solvents

Hydrodeoxygenation (HDO) of dibenzofuran is studied using density functional theory (DFT) with SMD implicit solvation model to give products like benzene and cyclohexane. Water and methanol are used as solvents, and gas-phase calculations are also performed for comparison. HDO is proposed via two major route- 1) saturation of phenyl rings followed by deoxygenation, 2) cleavage of C-O bond for oxy -removal followed by ring saturation. First, thermochemical parameters like Gibbs free energy change and enthalpy change are calculated at varying temperature in gas, water and methanol. Then, the solvation free energy is calculated for methanol and water to determine the ease of separation of products from the solvents. Finally, a Single Point Energy calculation is performed in the gas phase. It is found that water is the best solvent among three mediums and offers a significant advantage in some reactions such as the conversion of dibenzofuran to 1,2,3,4,4a,9b-hexahydrodibenzo[b,d]furan, 2-cyclohexyl phenol to bicyclo-hexan-2-ol and biphenyl to cyclohexyl benzene. Water is also found to be a better medium for separation of all the intermediates and products from the solvent over methanol. The effect of temperature was also studied, and it was found that the increase in temperature is unfavourable in all mediums for almost all reactions.

Intrinsic role of pH in altering catalyst properties of NiMoP over alumino-silicate for the vapour phase hydrodeoxygenation of methyl heptanoate

Ni₂P, MoP, and NiMoP supported on MAS (10) were successfully prepared using acid and base regulators. The intrinsic role of pH and synergic factors has altered the physicochemical properties of the catalysts, which are responsible for HDO activity.