Alkene hydrogenation catalyzed by rhenium carbonyls bonded to highly dealuminated Y zeolite: spectroscopic characterization of the working catalyst

• Published in: Journal of molecular catalysis. A, Chemical Vol. 204; pp. 473 - 481
• Main Authors: Enderle, Bryan, Gates, Bruce C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.09.2003
• Subjects: Ethylene hydrogenation; EXAFS spectroscopy; In situ spectroscopy; Spectroscopy of working catalyst; Supported rhenium complex; EXAFS spectroscopy; Spectroscopy of working catalyst; Supported rhenium complex; In situ spectroscopy; Ethylene hydrogenation
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/S1381-1169(03)00329-7

Bonding of Re(CO) 3 in zeolite DAY. Key: O, red; Si, gray; Al, light blue; C, green; Re, dark blue. Distances are given in Å. This is the precursor of a catalyst for alkene hydrogenation; changes in the coordination of the Re atom to the zeolite during catalysis were observed by EXAFS spectroscopy, and evidence of reaction intermediates was obtained by IR spectroscopy. Rhenium carbonyls bonded to dealuminated zeolite Y calcined at 300 and at 500 °C were tested as catalysts for hydrogenation of ethylene and of propylene and characterized by infrared (IR) and extended X-ray absorption fine structure (EXAFS) spectroscopies, even under catalytic reaction conditions. The initially formed rhenium tricarbonyls bonded to the zeolite were converted into rhenium dicarbonyls during catalysis, as shown by IR and EXAFS spectra, and the coordination of the Re to the support changed, as shown by EXAFS results. Consequently, there were bonding positions on the Re centers for reactive ligands, including those identified by IR spectroscopy as alkyls and π-bonded alkenes. The catalysis is suggested to proceed via reaction of alkyl and hydride ligands on rhenium centers incorporating two CO ligands.