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SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE TO Y-BUTROLACTONE OVER PD/AL2O3 CATALYST USING SUPERCRITICAL CARBON DIOXIDE MEDIUM
Citation:
Pillai**, U R. AND E SahleDemessie*. SELECTIVE HYDROGENATION OF MALEIC ANHYDRIDE TO Y-BUTROLACTONE OVER PD/AL2O3 CATALYST USING SUPERCRITICAL CARBON DIOXIDE MEDIUM. Atwood, J.L. (ed.), CHEMICAL COMMUNICATIONS. Royal Society of Chemistry, Cambridge, Uk, 5:422-423, (2002).
Description:
Hydrogenation of maleic anhydride to g-butyrolactone over Pd/Al2O3 catalyst under supercritical carbondioxide medium
Unnikrishnan R. Pillai and Endalkachew Sahle-Demessie
National Risk Management Research laboratory (NRMRL), Clean Processes Branch, MS 443, United States-Environmental Protection Agency (US-EPA), Cincinnati, Ohio-45268, USA
E-mail: Sahle-Demessie.Endalkachew@epa.gov, Fax: 011-513-569-7677
Hydrogenation of maleic anhydride (MA) to either g-butyrolactone (GBL) or succinic anhydride (SAH) is described at 150-200oC and 2MPa H2 pressure over simple Pd/Al2O3 catalyst under supercritical CO2 medium. Selectivities different from normal liquid phase hydrogenations in organic solvents are being reported here at 100% MA conversion under supercritical conditions, showing the potential of the supercritical medium for partial hydrogenations. Product selectivity varies significantly with changes in temperature, pressure as well as the reaction medium. GBL selectivity increases with increase in CO2 pressure and temperature. Temperature is critical in obtaining the desired GBL yield. Maximum GBL selectivity is obtained at 12MPa CO2 at 200oC. Solubility studies of MA in Sc-CO2 at 50oC and 150oC in the presence of 2MPa hydrogen pressure show complete dissolution of MA at 12MPa CO2. The unusual GBL selectivity obtained may be a consequence of the enhanced reactant-product solubility as well as different reaction energetics in supercritical CO2 medium. This has considerable promise for both lab-scale as well as industrial selective hydrogenations of low vapor pressure compounds without employing environmentally harmful organic solvents.