Alcohol synthesis over cesium-promoted copper/zinc oxide catalysts: Surface species, mechanistic pathways, and catalyst lifetime

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:6373268

Bogdan, C E

Under methanol synthesis conditions, Cs salt addition to the Cu/ZnO catalyst promoted the synthesis rates of methanol, methyl formate and ethanol. Using {sup 13}CH{sub 3}OH and {sup 12}CO/H{sub 2}, {sup 13}C-NMR analysis of the products synthesized evidenced the formation of methyl formate by the direct carbonylation of methanol whereas ethanol was formed by coupling of oxygenated C{sub 1} intermediates formed from the enriched methanol. Cs promotion of the Cu/ZnO catalyst increased the synthesis rates of the higher oxygenates, especially 2-methyl-1-propanol. Injection of C-13 enriched ethanol into the synthesis gas demonstrated that the synthesis of higher alcohols involves pathways of linear and branched C chain growth. The growth is dominated by C, oxygenate addition to the {beta}-carbons of oxygenated intermediates as well as by linear addition. Over the undoped Cu/ZnO catalyst, only the linear chain growth of ethanol was observed, CH{sub 3}{sup 13}CH{sub 2}OH + CO/H{sub 2}{r arrow} CH{sub 3} {sup 13}CH{sub 2}CH{sub 2}OH while Cs promoted {beta}-carbon addition, CH{sub 3}{sup 13}CH{sub 2}OH + CO/H{sub 2}{r arrow} {sup 13}CH{sub 3} CH{sub 2}CH{sub 2}OH. The isotope labeling evidenced the retention of the oxygen associated with the C{sub 1} intermediate formed from CO/H{sub 2} and loss of the oxygen from the {sup 13}CH{sub 2}OH group of ethanol. The mechanism has been proposed to proceed via a {beta}-ketoalkoxide intermediate, the mechanism termed as aldol coupling with oxygen retention reversal. Higher oxygenate synthesis also proceeds by oxygen retention reversal and normal oxygen retention in the coupling reactions, the pathways observed attributed to steric effects involving the {beta}-alkoxide intermediates. Catalytic lifetime tests were performed under higher alcohol synthesis conditions. Careful control of the testing conditions demonstrated the intrinsic stability of the Cs promoted Cu/ZnO catalyst.

• Research Organization: Lehigh Univ., Bethlehem, PA (USA)
• OSTI ID: 6373268
• Country of Publication: United States
• Language: English

Related Subjects

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ADDITIVES
ALCOHOLS
ALDEHYDES
ALKALI METAL COMPOUNDS
CARBON 12
CARBON 13
CARBON COMPOUNDS
CARBON ISOTOPES
CARBON MONOXIDE
CARBON OXIDES
CARBOXYLIC ACID SALTS
CATALYTIC EFFECTS
CESIUM COMPOUNDS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COPPER
DOPED MATERIALS
ELEMENTS
ETHANOL
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
FORMALDEHYDE
FORMATES
HYDROGENATION
HYDROXY COMPOUNDS
INFRARED SPECTRA
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
MATERIALS
METALS
METHANATION
METHANOL
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PROMOTERS
PROPANOLS
REACTION INTERMEDIATES
REACTION KINETICS
RESONANCE
SPECTRA
STABLE ISOTOPES
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS
ZINC COMPOUNDS
ZINC OXIDES