Enantioselective hydrogenation of ethyl pyruvate in supercritical fluids

Hydrogenation of phenol with supported Rh catalysts in the presence of compressed CO2: Its effects on reaction rate, product selectivity and catalyst life

“…11) that the adsorbed CO was produced from CO 2 -H 2 , although no gaseous CO was detected in the gas phase after the hydrogenation runs in the presence of CO 2 . Several research groups reported, by FTIR (not in situ), the formation of adsorbed CO from CO 2 -H 2 mixtures via reverse water gas shift reaction over Pt [37][38][39][40], Rh [40], Ru [40,41], and Pd [40,41] catalysts even at such a low temperatures as 323 K. Some authors have also shown that adsorbed CO suppresses hydrogenation of ethyl pyruvate over Pt/Al 2 O 3 [38] and dechlorination of chloroaniline over Pt/C [39]. Hence, the formation and adsorption of CO should retard the phenol hydrogenation by blocking Rh active site.…”

“…These CO 2 -dissolved expanded liquid phases are demonstrated to be interesting reaction media for reactions including gaseous reactants like O 2 , H 2 , and CO. Moreover, it is reported that CO may be formed in hydrogenation reactions with supported noble metal catalysts in scCO 2 and this has negative impacts on the catalytic activity and, subsequently, the reaction rate and selectivity [37][38][39][40][41][42].…”

“…Furthermore, in situ high-pressure transmittance FTIR measurements have been made to study the molecular interactions of the reacting species with CO 2 and the formation and adsorption of CO on the catalysts at high pressures. In situ high-pressure measurement of the formation of CO from pressurized CO 2 and H 2 over supported metal catalysts was studied only by Baiker et al, who used attenuated total reflection infrared (ATR-IR) spectroscopy [37,38,40].…”

Heterogeneous Catalysis in Supercritical Media, Part 3: Other Media

“…Enantioselective hydrogenation of ethyl pyruvate to ethyl lactate took place in supercritical ethane and for comparison in liquid toluene with a platinum catalyst on an aluminum oxide support [44][45][46]. The catalyst was modified with cinchonidine to generate chiral active centers.…”

In situ FTIR study on the formation and adsorption of CO on alumina-supported noble metal catalysts from H2 and CO2 in the presence of water vapor at high pressures

“…Using in situ high pressure FTIR techniques, a few authors investigated this phenomenon important in catalytic hydrogenation and other reactions in the presence of dense phase CO 2 . [9][10][11][12][13][14][15] Baiker et al used attenuated total reflection infrared spectroscopy (ATR-IR) to follow the reaction of CO 2 with H 2 over alumina-supported Pt catalyst in the form of thin film in cyclohexane at 313 K. 9,10,12 It is indicated that carbonate-like species are formed from CO 2 adsorbed on the support and then react with H 2 , forming CO. The formation of CO was responsible for the catalyst deactivation observed in hydrogenation of ethyl pyruvate in supercritical CO 2 .…”