Selective hydrogenation of cinnamaldehyde in supercritical CO sub(2) over Pt/SiO sub(2) and Pt/HS-CeO sub(2): An insight about the role of carbonyl interaction with supercritical CO sub(2) or with ceria support sites in cinamyl alcohol selectivity

• Published in: Applied catalysis. A, General Vol. 467; pp. 253 - 260
• Main Authors: Piqueras, Cristian M, Gutierrez, Victoria, Vega, Daniel A, Volpe, Maria A
• Format: Journal Article
• Language: English
• Published: 02.10.2013
• Subjects: Carbon dioxide; Catalysis; Catalysts; Cerium oxide; Hydrogenation; Platinum; Selectivity; Silicon dioxide
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2013.07.028

The catalytic hydrogenation of cinnamald?hyde employing H sub(2) as the reductant was carried out under supercritical (sc) CO sub(2), propane and other CO sub(2) dense mixture, employing Pt supported on silica and high surface (HS) ceria. The phase behavior of the mixtures was found to be in good agreement with the predictions obtained from the MHV2 (modified Huron-Vidal second-order) model. In order to study the influence of scCO sub(2) on the selectivity, the reaction was also conducted in dense propane and near-critical CO sub(2)-isopropanol mixtures. These results were compared with those corresponding to classical gas-liquid conditions with isopropanol as solvent and low H sub(2) pressure. In scCO sub(2), the selectivity to cinnamyl alcohol over Pt/SiO sub(2) was 91%, quite higher than under classical conditions (38%). Such an enhancement is originated by the interaction of the C=O with scCO sub(2). For Pt/HS-CeO sub(2) the selectivity under supercritical conditions was slightly lower (80%) than the one corresponding to Pt/SiO sub(2) but quite higher than the one corresponding to gas-iiquid conditions (54%). The interaction of the carbonyl group with ceria support predominates in this case, thus, the beneficial effect of scCO sub(2) is not observed in the same magnitude as in the case of Pt/SiO sub(2). A catalytic scenario is drawn for each catalyst in order to explain the different selectivity patterns.