The direct and stable conversion of ethanol to propene with yields up to 60 mol % was achieved on scandium-modified indium oxide catalysts at 823 K in the presence of water and hydrogen. The reaction pathways are also suggested, ethanol ¼ acetaldehyde ¼ acetone ¼ propene, which is quite different from those on zeolites and on nickel ion-loaded silica catalysts.The use of bio-ethanol (bEtOH) as automobile fuels has increased rapidly over the world with expanded availability and reduced cost. 13 The conversion of this particular biomass-based feedstock to highly valuable chemicals has also been an important research goal.47 Direct conversion to propene and isobutene has very recently been reported on nickel ion-loaded mesoporous silica Ni-MCM-41 (Ni-M41) 8 and also a mixed oxide Zn 1 Zr 10 O z .9 Propene production is notably desirable, due to the increasing demand for propene derivatives such as propene oxide, acrylonitrile, and polypropene. Catalytic conversion of EtOH on zeolites has widely been reported, but the selectivity toward propene was approximately 2030% and decreased with reaction time. 10 Various oligomerization and scission reactions on strong acid sites in the zeolite pores lead to ethene, propene, and butenes due to the shape selectivity of pore windows. However, reactions in the pores eventually result in coke formation and short lifetimes of catalysts. On the other hand, Ni-M41 was active for the propene synthesis through dehydration, dimerization, isomerization, and metathesis. 8,11 Our additional experiments on the Ni-M41 process indicated deactivation of Ni-M41 at 30 vol % of ethanol during practical application. New catalyst(s) usable under practical conditions, therefore, should be developed to produce biochemicals and bioplastics from bio-ethanol.Our attention was focused on the formation of ketones from alcohols in which C x -alcohols are converted into C 2x¹1 -ketones; for example, ethanol to acetone on ZnOFe 2 O 3 etc.7,12,13 and 1-propanol to 3-pentanone on CeO 2 Fe 2 O 3 .14 It is expected that mixed oxide catalysts with hydrogenationdehydration activity for acetone (Reaction 3) could directly convert ethanol to propene (Reaction 4), though there has been no report on direct conversion through the suggested pathways.Our study revealed that In 2 O 3 -based oxides were notably active for the direct conversion of ethanol to propene, and the propene yield reached approximately 60% at 30% partial pressure of ethanol. The reaction pathways were also suggested based on the change in the products.Indium oxide, In 2 O 3 (4.2 m 2 g ¹1 after calcination at 1073 K for 5 h), was commercially obtained from Kanto Chemical Co. Japan. Metal-loaded In 2 O 3 samples were prepared by a conventional impregnation method using mainly nitrate salts. Metal loadings were determined by inductively coupled plasma analysis after the samples were dissolved in HF solutions. All catalysts were calcined at 1023 K for 5 h, and the respective particle sizes were adjusted to 300600¯m for use in catalytic runs. The struc...
Potential reaction intermediates in the conversion of ethanol to propene, acetaldehyde, ethyl acetate, crotonaldehyde, acetic acid, acetone, and 2-propanol were introduced as pulses onto a scandium-loaded indium oxide catalyst. The product distributions were primarily measured as a function of the space velocity in the absence or presence of hydrogen and water. The FT-IR spectra of the surface adsorbates were also collected after ethanol adsorption and indicated the formation of ethoxide species, which were converted to acetate species over the catalyst. The proposed reaction route involved the dehydrogenation of ethanol to acetaldehyde, direct oxidation of acetaldehyde with water or a surface hydroxyl group to yield acetic acid, ketonization of acetic acid to acetone and carbon dioxide, and hydrogenation and subsequent dehydration of acetone to propene. The total reaction can be described as 2 CH3CH2OH → CH2CHCH3 + CO2 + 3 H2. A side reaction involving isobutene formation also occurred via the acetone intermediate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.