02878nas a2200277   4500008004100000022001400041245014900055210006900204260000800273300001600281490000600297520188700303653003702190653001702227653000802244653002302252653001302275653002002288653003002308100002502338700002202363700002902385700002602414700002902440856013102469       2021                        eng d  a2168-048500aMechanistic investigations on the catalytic transfer hydrogenation of lignin-derived monomers over Ru catalysts: theoretical and kinetic studies0 aMechanistic investigations on the catalytic transfer hydrogenati  cOCT  a14040-140500 v93 aThe hydrodeoxygenation (HDO) reaction of oxygenated compounds such as lignin-derived phenolics is well studied using molecular H-2 as a hydrogen source, yet the use of high pressures discourages its use on an industrial scale. As an alternative, the catalytic transfer hydrogenation (CTH) pathway provides in situ hydrogenation species, which reduces the need for the high-pressure infrastructure required when molecular hydrogen is used. Nevertheless, this strategy is scantly studied, and in lieu with this, herein we report the kinetic and mechanistic investigations of the CTH strategy for the HDO of guaiacol, phenol, anisole veratrole, and eugenol to their respective products. For potential commercialization purposes, low loading of metal, milder reaction conditions, and high selectivity toward desired products with a high H/C ratio were considered while designing catalysts (0.5 wt % Ru on SiO2-Al2O3, SiO2, Al2O3-acidic, Al2O3-basic, and Al2O3-neutral) for these reactions. As high as 74% cyclohexanol yield from guaiacol was achieved at 225 degrees C in the presence of isopropyl alcohol (IPA) as the hydrogen source and over the Ru/Al2O3-acidic catalyst reduced at 150 degrees C. A detailed kinetic study is carried out to understand the interaction of the substrate and intermediates with the catalyst and the influence of reaction parameters on the product formation. It was observed that the cisisomer of 2-methoxycyclohexanol rapidly undergoes further conversion than the trans-isomer. The experimental observations are substantiated through density functional theory (DFT) studies on Ru(0001) and guaiacol molecule complexes. DFT studies indicate that the adsorption of the cis-isomer is more exothermic as compared to that of the trans counterpart, and the underlying electronic factors are elucidated using charge density difference and density of states plots.10acatalytic transfer hydrogenation10aCyclohexanol10aDFT10aHydrodeoxygenation10akinetics10alignin monomers10aSupported metal catalysts1 aKhan, Tufeil, Sartaj1 aSingh, Dheerendra1 aSamal, Pragnya, Paramita1 aKrishnamurty, Sailaja1 aDhepe, Paresh, Laxmikant  uhttps://library.ncl.res.in/content/mechanistic-investigations-catalytic-transfer-hydrogenation-lignin-derived-monomers-over-ru02480nas a2200325   4500008004100000245010800041210006900149260000800218300001400226490000600240520139800246653001601644653002401660653002601684653002301710653001501733653001701748100002101765700002601786700002901812700002901841700002501870700002601895700002101921700002201942700001601964700002601980700002602006856012202032       2023                        eng d00aMnXWO4 nanostructure-based catalysts for single-step oxidation of cyclohexane and methane to oxygenates0 aMnXWO4 nanostructurebased catalysts for singlestep oxidation of   cAPR  a7245-72580 v63 a<p>
	Activation of the C-H bond in cyclohexane (CYH) and methane is a crucial step to obtain desirable oxygenated products using nanostructured catalyst and is a great challenge and an efficient route to mitigate the inauspicious effects of climate change. The active sites were identified using XRD, HR-TEM, SEM, N2 sorption analysis, TPR, Raman, XPS, TGA, in situ DRIFT, XAS, etc. In optimal reaction conditions, 46% of CYH was converted into adipic acid (AA) on MnxWO4 nanostructures within 6 h. The recyclability test confirmed the catalyst heterogeneity, which revealed no appreciable loss of catalytic activity even after three consecutive reactions. In situ DRIFT study reveals that CYH is oxidized to cyclohexanone and cyclohexanol (KA oil) and is further oxidized to AA via carboxylate intermediates. DFT studies disclosed that MnOx species are responsible for the C-H activation of CYH, and the Mn2+/Mn3+ redox centers play a vital role in the absorption of KA oil to form AA. Herein, we demonstrated the significant role of the ``MnOx'' species and that adequate Lewis and Bronsted acidic sites, redox centers of (Mn2+/Mn3+), and lattice oxygen are accountable for the CYH conversion toward the AA. Additionally, we have reported the oxidation of methane to methanol (146 mu mole per gram of catalyst) in the presence of water at 75 degrees C without over-oxidation products.</p>
10aAdipic Acid10aC-H bond activation10aCyclohexane oxidation10amethane activation10aMnOx chain10aRedox center1 aPrabu, Marimuthu1 aManikandan, Marimuthu1 aSamal, Pragnya, Paramita1 aGurrala, Lakshmi, Prasad1 aMekala, Siva, Prasad1 aArchana, Ramakrishnan1 aNayak, Chandrani1 aBhattacharyya, D.1 aJha, S., N.1 aKrishnamurty, Sailaja1 aRaja, Thirumalaiswamy  uhttps://library.ncl.res.in/content/mnxwo4-nanostructure-based-catalysts-single-step-oxidation-cyclohexane-and-methane