01797nas a2200265   4500008004100000022001400041245011200055210006900167260007300236300001000309490000800319520082700327653001701154653001301171653004001184653004201224653002101266653001801287653003301305100002201338700001701360700001301377700001501390856012601405       2005                        eng d  a0926-860X00aBiphenyl hydrogenation over supported transition metal catalysts under supercritical carbon dioxide solvent0 aBiphenyl hydrogenation over supported transition metal catalysts  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL  a43-470 v2883 a<p>Catalytic hydrogenation of biphenyl to bicyclohexyl, an organic hydrogen storage medium, was examined over supported transition metal catalysts in supercritical carbon dioxide solvent. The yield of bicyclohexyl was almost 100% over the charcoal-supported rhodium (Rh/C) and ruthenium (Ru/C) catalysts at the temperature of 323 K, which was much lower than that required for biphenyl hydrogenation in organic solvents (573 K). The initial activity was higher over the Rh/C catalyst, while the initial selectivity to bicyclohexyl was higher over the Ru/C catalyst. The conversion of biphenyl increased with increase in hydrogen and carbon dioxide pressures, while the selectivity to bicyclohexyl was independent of hydrogen and carbon dioxide pressures over both catalysts. (c) 2005 Elsevier B.V. All rights reserved.</p>10abicyclohexyl10abiphenyl10acharcoal-supported rhodium catalyst10acharcoal-supported ruthenium catalyst10aHydrogen storage10aHydrogenation10aSupercritical carbon dioxide1 aHiyoshi, Norihito1 aRode, C., V.1 aSato, O.1 aShirai, M.  uhttps://library.ncl.res.in/content/biphenyl-hydrogenation-over-supported-transition-metal-catalysts-under-supercritical-002378nas a2200241   4500008004100000022001400041245013600055210006900191260009500260300001000355490000800365520138100373653004001754653003401794653004101828653002701869100002201896700002901918700001601947700002201963700002101985856013002006       2007                        eng d  a0021-951700aStereoselective hydrogenation of tert-butylphenols over charcoal-supported rhodium catalyst in supercritical carbon dioxide solvent0 aStereoselective hydrogenation of tertbutylphenols over charcoals  a525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USAbACADEMIC PRESS INC ELSEVIER SCIENCEcNOV  a57-680 v2523 a<p>Hydrogenation of 2-, 3-, and 4-tert-butylphenols was studied over a charcoal- supported rhodium catalyst in supercritical carbon dioxide (scCO(2)) solvent, and the results were compared with those in organic solvents. In the hydrogenation of 4-tert-butylphenol, a higher cis ratio for 4-tert-butylcyclohexanol (0.79) was obtained in scCO(2) (10 MPa) than in 2-propanol (0.70) and cyclohexane (0.64) under similar conditions of hydrogen pressure (2 MPa) and temperature (313 K). In the case of 2-tert-butylphenol, the cis ratio for 2-tert-butylcyclohexanol was as high as 0.95 in both scCO(2) and 2-propanol (hydrogen pressure, 2 MPa; reaction temperature, 313 K). In the case of hydrogenation of 3-tert-butylphenol, the cis ratio decreased with the progression of consecutive hydrogenation of 3-tert-butylcyclohexanone intermediate. In addition, the stereoselectivity to cis-tert-butylcyclohexanols in scCO(2) was improved in the presence of hydrochloric acid. It was found that the protons of hydrochloric acid accelerated the hydrogenation of the intermediates, tert-butylcyclohexanones, to the corresponding cis-tert-butylcyclohexanols. The hydrogenation mechanism of tert-butylphenols, particularly the enhanced selectivity to cis-tert-butylcyclohexanols in scCO(2), is postulated based on the observed reaction profiles. (c) 2007 Elsevier Inc. All rights reserved.</p>10acharcoal-supported rhodium catalyst10astereoselective hydrogenation10asupercritical carbon dioxide solvent10atert-butylcyclohexanol1 aHiyoshi, Norihito1 aRode, Chandrashekhar, V.1 aSato, Osamu1 aTetsuka, Hiroyuki1 aShirai, Masayuki  uhttps://library.ncl.res.in/content/stereoselective-hydrogenation-tert-butylphenols-over-charcoal-supported-rhodium-catalyst-0