One-path and Selective Conversion of Ethanol to Propene on Scandium-modified Indium Oxide Catalysts

Abstract

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...

Selective Production of Aromatics from 2-Octanol on Zinc Ion-Exchanged MFI Zeolite Catalysts

“…The uniformity of MCM-41 resulted in excellent selectivity of products in various organic synthesis reactions [29][30][31][32][33][34][35]. In the current reaction on MCM-41, C5 and C3 compounds were obtained stoichiometrically with 100% conversions of 2-octanol at 623-773 K, and no further reaction, such as the scission reaction of C-C bonds of the C5 compounds, was observed due to the weak acidity of the MCM-41 catalyst [36][37][38][39][40][41]. The MCM-41 and the Zn-MFI catalysts were mounted in a series into the reactor and used for the reaction of 2-octanol.…”

“…These reaction pathways were further supported by the following experiments. Mesoporous silica materials containing very small amounts of aluminum ions, MCM-41, were reported to exhibit weak and uniform acid sites [29][30][31][32][33][34][35][36][37][38][39][40][41]. The uniformity of MCM-41 resulted in excellent selectivity of products in various organic synthesis reactions [29][30][31][32][33][34][35].…”

The role of m-ZrO2 in the selective oxidation of ethanol to acetic acid employing PdO/m-ZrO2

“…It can generate many different chemicals, including ethyl acetate [1][2][3][4], 1-butanol [5,6], acetone [7], propene [8], isobutene [9], 1,3 butadiene [10] in a one-pot reaction employing multifunctional catalysts.…”

Yttrium-Modified Ceria As a Highly Durable Catalyst for the Selective Conversion of Ethanol to Propene and Ethene

“…The decrease in the activity of Ni-M41 was not improved by addition of water, and the activity of Sc/In 2 O 3 became stabilized in the presence of water. 24 Currently, catalysts that are stable in the absence of water have been required to achieve the effective catalytic conversion of ethanol to lower olefins.Various neutral and acid−base oxides have been examined for conversion of ethanol to related substances. 11−25 In addition to ethene, the major products reported were oxygenated compounds, such as aldehydes and ketones.…”

“…Very recently, the conversion of ethanol to propene was reported on nickel ion-loaded mesoporous silica MCM-41 (Ni-M41) 23 and Sc-loaded In 2 O 3 . 24 Although these oxide catalysts produced new types of catalysis for the production of propene without shape selectivity, the catalytic activity gradually decreased with the reaction time at 30 vol % of ethanol (the high concentration of ethanol was required to reduce running costs of the practical process). The decrease in the activity of Ni-M41 was not improved by addition of water, and the activity of Sc/In 2 O 3 became stabilized in the presence of water.…”