Metal-support effects on the intramolecular selectivity of crotonaldehyde hydrogenation over platinum
- Pennsylvania State Univ., University Park (USA)
The vapor-phase hydrogenation of crotonaldehyde (CROALD) was studied at low temperature and low conversions over Pt powder and Pt dispersed on SiO{sub 2}, {eta}-Al{sub 2}O{sub 3}, and TiO{sub 2} after either a high- or a low-temperature reduction, HTR and LTR, respectively. The hydrogenation of butyraldehyde (BUTALD) and crotyl alcohol (CROALC) to butanol (BUTNOL) and the isomerization of CROALC to BUTALD were also investigated to obtain additional information about this network of reactions. The typical Pt catalysts produced 100% BUTALD. However, the TiO{sub 2}-supported Pt produced both CROALC and BUTNOL, and the best catalyst, (HTR) Pt/TiO{sub 2}, gave a selectivity of 37% CROALC with no BUTNOL formation. The turnover frequencies on the (HTR) Pt/TiO{sub 2} samples, based on sites counted by hydrogen chemisorption near reaction temperatures, were more than an order of magnitude higher than the catalysts displaying normal adsorption behavior. Activation energies were somewhat higher on the Pt/TiO{sub 2} catalysts, however. This behavior is very similar to that observed previously for CO and acetone hydrogenation over these same catalysts, and it is consistent with the proposal that sites created at the Pt-titania interface are responsible for the activation of carbonyl bonds. Previous studies of liquid-phase hydrogenation of CROALD and other molecules with conjugated C{double bond}C and C{double bond}O double bonds support this model and indicate that a 1,4 diadsorbed species, rather than 1,2 and 3,4 diadsorbed species (counting the oxygen atom as 1), is formed in polar solvents. By analogy, defect sites on the titania at the metal-support interface may interact with the O atom, polarize the C{double bond}O bond, and favor this intermediate which can react with hydrogen to give CROALC. 48 refs.
- DOE Contract Number:
- FG02-84ER13276
- OSTI ID:
- 7130582
- Journal Information:
- Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 115:1; ISSN 0021-9517; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Crotonaldehyde hydrogenation on Pt/TiO{sub 2} and Ni/TiO{sub 2} SMSI catalysts
The selective hydrogenation of crotonaldehyde over bimetallic catalysts
Related Subjects
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ALDEHYDES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
ELEMENTS
ENERGY
HYDROGEN
HYDROGENATION
ISOMERIZATION
KINETICS
METALS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
REACTION INTERMEDIATES
REACTION KINETICS
REDUCTION
SAMPLE PREPARATION
SEPARATION PROCESSES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS