@article {46306, title = {Understanding the influence of alumina supported ruthenium catalysts synthesis and reaction parameters on the hydrodeoxygenation of lignin derived monomers}, journal = {Molecular Catalysis}, volume = {480}, year = {2020}, month = {JAN}, pages = {UNSP 110525}, type = {Article}, abstract = {

Up-gradation of lignin derived monomers to value-added and fuel grade products is important to make overall bio-refinery process economical. Although, few studies are devoted on this work yet, systematic study on commercially viable (low loading of metal, recyclable catalyst, mild conditions, high selectivities etc.) is scarce and typically done under harsh conditions. Herein, we report, the methodical effect of support (SiO2, Al2O3 (acidic, basic and neutral), SiO2-Al2O3) on the hydrodeoxygenation (HDO) of lignin derived various monomers, guaiacol, veretrol, eugenol, phenol using very low loading (0.5 wt\%) Ru catalyst. Very high yield (82\%) of cyclohexanol from guaiacol could be achieved in presence of cyclohexane as a solvent and Ru/Al2O3-Acidic catalyst at 225 degrees C and under 1 MPa H-2 pressure. The detailed study on the effect of solvent, stability and adsorption of reactant \& products etc. is done and it was observed that products are more prone to adsorb and undergo further reactions. The complete characterization of fresh and spent catalysts revealed that lower catalyst reduction temperature and presence of Ru in partially higher oxidation state proved by XPS, helps in enhancing the cyclohexanol formation. Subsequently, role of Ru particle size and support on the activity was also investigated.

}, keywords = {Cyclohexanol, Hydrodeoxygenation, lignin, reaction pathway, supported metal catalyst}, issn = {2468-8231}, doi = {10.1016/j.mcat.2019.110525}, author = {Singh, Dheerendra and Dhepe, Paresh L.} } @article {47109, title = {Efficient catalytic transfer hydrogenation-hydrodeoxygenation of lignin derived monomers: investigating catalyst properties-activity correlation}, journal = {Catalysis Communications}, volume = {149}, year = {2021}, month = {JAN }, pages = {106220}, type = {Article}, abstract = {

Reduction of O/C ratio of lignin derived monomers via hydrodeoxygenation (HDO) pathway is conventionally furnished using molecular hydrogen under severe conditions. Nonetheless, due to a prerequisite to accomplish HDO through commercially attractive methodology we report, HDO reactions of various phenolic compounds via catalytic transfer hydrogenation (CTH) pathway using very low loading of Ru (0.5 wt\%) on neutral and acidic Al2O3 under nitrogen atmosphere. With guaiacol as a substrate, 74\% cyclohexanol yield at 225 degrees C in the presence of IPA is realized. Bi-functionality of metal state, acidity of support and nature of alcohol are perceived to be responsible for the variation in activity.

}, keywords = {Catalytic transfer hydrogenation (CTH), Cyclohexanol, Hydrodeoxygenation, lignin, Supported metal catalysts}, issn = {1566-7367}, doi = {10.1016/j.catcom.2020.106220}, author = {Singh, Dheerendra and Dhepe, Paresh L.} } @article {49797, title = {Continuous flow hydrodeoxygenation of lignin-derived guaiacol to cyclohexanol over durable Al2O3 hollow fiber supported co catalyst}, journal = {ChemCatChem}, volume = {17}, year = {2025}, month = {SEP}, type = {Article}, abstract = {

The drive to decarbonize the chemical, oil, and gas industries through use of bio-derived resources is intensifying. This study focuses on converting lignin-derived phenolic compounds into cyclohexanol, a precursor for adipic acid production. The alumina hollow fiber supported cobalt catalyst (5Co/AHF@capillary) prepared by capillary action method was found to consist cobalt in both metallic and +delta oxidation states. Initial tests in a batch-mode reactor showed promising results, with 5Co/AHF@capillary catalyst demonstrating catalytic activity comparable to Ru/Al2O3 systems (225 degrees C, 1 MPa H-2, 4 h), achieving similar to 86\% cyclohexanol yield in guaiacol hydrodeoxygenation reactions. The catalytic system was then adapted for continuous flow reactors under milder conditions (300 degrees C, 2.5 MPa H-2, 18 mL min(-1)), resulting in 83\% guaiacol conversion and 74\% cyclohexanol yield. The durability of the catalyst was checked for \>80 h and results claim that catalyst was active in yielding consistent results. The roles of catalyst preparation method, hydrogen pressure, solvent, WHSV were thoroughly checked and discussed.

}, keywords = {biomass valorization, Carbon, Co/Al2O3, Cyclohexanol, lignin}, issn = {1867-3880}, doi = {10.1002/cctc.202500656}, author = {Singh, Dheerendra and Jogdand, Shunottara M. and Devi, R. Nandini and Dhepe, Paresh L.} }