Transition Metal B-Site Substitutions in LaAlO3 Perovskites Reorient Bio-Ethanol Conversion Reactions

LaAlO3 perovskites, as such and with 25% molar Al substitution by Cu, Co, or Ga, have been prepared by sol-gel methods and tested as heterogeneous catalysts in the gas-phase conversion of ethanol. LaAlO3 presented a significant acidic character, with high formation of ethylene by ethanol dehydration...

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Bibliographic Details
Published in:Catalysts 2021-03, Vol.11 (3), p.344
Main Authors: Tran, Quang Nguyen, Gimello, Olinda, Tanchoux, Nathalie, Ceretti, Monica, Albonetti, Stefania, Paulus, Werner, Bonelli, Barbara, Di Renzo, Francesco
Format: Article
Language:English
Subjects:
Acetaldehyde
Acetone
Acids
Alcohols
Aldehydes
Alkenes
Aluminum
Basicity
Biodiesel fuels
Biofuels
Butadiene
Catalysts
Chemical reactions
Chemical Sciences
Condensates
Conversion
Copper
Dehydration
Dehydrogenation
Ethanol
Ethylene
Gallium
Hexadiene
Materials substitution
Perovskites
Polyolefins
Sol-gel processes
Transition metals
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Summary:LaAlO3 perovskites, as such and with 25% molar Al substitution by Cu, Co, or Ga, have been prepared by sol-gel methods and tested as heterogeneous catalysts in the gas-phase conversion of ethanol. LaAlO3 presented a significant acidic character, with high formation of ethylene by ethanol dehydration. B-site substitutions increased the basicity of the catalysts, favoring the dehydrogenation of ethanol to acetaldehyde. The most reducible Cu- and Co-substituted materials, characterized by easier formation of surface oxygen vacancies, promoted the self-condensation of acetaldehyde by the Tishchenko mechanism, with formation of acetone and odd-carbon number products. Aldol coupling of acetaldehyde, favored on pure and Ga-substituted LaAlO3, led to the formation of butadiene and hexadiene. The role of Ga insertion, favoring both dehydrogenation of ethylene and dehydration of higher alcohols, corresponds to an amphoteric character. The formation of olefins and diolefins on all catalysts suggests that LaAl-based materials present the most acidic character among La-perovskites.
ISSN:2073-4344
2073-4344
DOI:10.3390/catal11030344