Metal-support effects on the intramolecular selectivity of crotonaldehyde hydrogenation over platinum

Journal Article · Sun Jan 01 00:00:00 EST 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90007-9· OSTI ID:7130582

Vannic, M A; Sen, B ^[1]

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1. 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), Vol. 115:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALDEHYDES
HYDROGENATION
PLATINUM
CATALYTIC EFFECTS
ACTIVATION ENERGY
ALUMINIUM OXIDES
CARBON MONOXIDE
CATALYSIS
CHEMICAL REACTION KINETICS
CHEMISORPTION
HYDROGEN
ISOMERIZATION
REACTION INTERMEDIATES
REDUCTION
SAMPLE PREPARATION
SILICA
TITANIUM OXIDES
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
ENERGY
KINETICS
METALS
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
SEPARATION PROCESSES
SILICON COMPOUNDS
SILICON OXIDES
SORPTION
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties