TY - GEN
T1 - Mechanisms and active sites for vapor-phase oxidation of ethylene to acetic acid over Pd-H4SiW12O40/SiO2
AU - Kawakami, T.
AU - Ooka, Y.
AU - Hattori, H.
AU - Chu, W.
AU - Kamiya, Y.
AU - Okuhara, T.
PY - 2007
Y1 - 2007
N2 - The selective oxidation of ethylene to acetic acid in vapor phase was studied over the catalysts composed of Pd and solid acid to elucidate the reaction mechanisms as well as the roles of Pd and acidic sites in promoting the reaction. Among several solid acid catalysts examined, H1SiW12O/SiO2 and WO3/ZrO2 exhibited high activities for the formation of acetic acid by combination with palladium. Contact time dependency of the products and the requirement of the presence of H2O indicated that acetic acid is formed through acetaldehyde formed by a Wacker-type reaction. This was also supported by the kinetic results that the ethanol oxidation to acetic acid is slower than both of the acetaldehyde oxidation and the ethylene oxidation to acetic acid. For the formation of acetic acid from ethylene, co-presence of Pd2+, Pd0, and acidic site (protonic acid site) was required. The Pd2+ sites were relevant to the Wacker-type reaction to form acetaldehyde from ethylene in the presence of H2O. The Pd2+ was reduced to Pd0 as acetaldehyde was formed. The oxidation of acetaldehyde to form acetic acid took place on the Pd0 sites, which may be different from the interfacial Pd sites. This is an abstract of a paper presented at the 17th Annual Saudi-Japanese Symposium on Catalysts in Petroleum Refining and Petrochemicals 2007 (Dhahran, Saudi Arabia 11/11-12/2007).
AB - The selective oxidation of ethylene to acetic acid in vapor phase was studied over the catalysts composed of Pd and solid acid to elucidate the reaction mechanisms as well as the roles of Pd and acidic sites in promoting the reaction. Among several solid acid catalysts examined, H1SiW12O/SiO2 and WO3/ZrO2 exhibited high activities for the formation of acetic acid by combination with palladium. Contact time dependency of the products and the requirement of the presence of H2O indicated that acetic acid is formed through acetaldehyde formed by a Wacker-type reaction. This was also supported by the kinetic results that the ethanol oxidation to acetic acid is slower than both of the acetaldehyde oxidation and the ethylene oxidation to acetic acid. For the formation of acetic acid from ethylene, co-presence of Pd2+, Pd0, and acidic site (protonic acid site) was required. The Pd2+ sites were relevant to the Wacker-type reaction to form acetaldehyde from ethylene in the presence of H2O. The Pd2+ was reduced to Pd0 as acetaldehyde was formed. The oxidation of acetaldehyde to form acetic acid took place on the Pd0 sites, which may be different from the interfacial Pd sites. This is an abstract of a paper presented at the 17th Annual Saudi-Japanese Symposium on Catalysts in Petroleum Refining and Petrochemicals 2007 (Dhahran, Saudi Arabia 11/11-12/2007).
UR - http://www.scopus.com/inward/record.url?scp=44649083170&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:44649083170
SN - 9781604238631
T3 - King Fahd University of Petroleum and Minerals, Research Institute - Annual Catalysts in Petroleum Refining and Petrochemicals Symposium Papers
SP - 73
EP - 83
BT - King Fahd University of Petroleum and Minerals - 17th Annual Saudi-Japanese Symposium on Catalysts in Petroleum Refining and Petrochemicals 2007
ER -