open access publication

Article, 2023

A study of the conversion of ethanol to 1,3-butadiene: effects of chemical and structural heterogeneity on the activity of MgO–SiO 2 mixed oxide catalysts

In: Reaction Chemistry & Engineering, ISSN 2058-9883, Volume 8, 3, Pages 718-731, 10.1039/d2re00450j

Contributors (8)

Szabó, Blanka (0000-0001-5746-172X) [1] Hutkai, Virág [2] Novodárszki, Gyula (0000-0001-9159-0330) [1] Lónyi, Ferenc (0000-0002-7251-118X) [1] Pászti, Zoltán [1] Fogarassy, Zsolt [3] Valyon, József [1] Barthos, Róbert (0000-0002-7917-1835) [1]

Affiliations

  1. [1] Institute of Materials and Environmental Chemistry
  2. [NORA names: Hungary; Europe, EU; OECD]
  3. [2] Erhvervsakademi Aarhus, Sønderhøj 30, 8260 Viby J, Denmark
  4. [3] Institute for Technical Physics and Materials Science
  5. [NORA names: Hungary; Europe, EU; OECD]

Abstract

MgO–SiO 2 catalysts were synthesized by using non-porous and mesoporous MgO for ethanol to butadiene reaction. Significantly higher butadiene yields were achieved over mesoporous MgO based catalysts. The ethanol-to-butadiene (ETB) transformation proceeds through consecutive reactions, involving hydrogenation/dehydrogenation, C–C coupling, and dehydration. Uniform active sites are needed to attain high catalytic selectivity. It is a challenge to generate a catalyst containing three kinds of co-operating active sites in high homogeneity. Lacking dehydration activity, basic MgO is active in converting ethanol mainly to acetaldehyde and butanol, whereas the main products obtained over SiO 2 catalysts are dehydration products ethylene and diethyl ether. 1,3-Butadiene could be obtained over MgO–SiO 2 mixed oxide catalysts, having acidic and basic sites of strength and concentration favoring all three reactions. Silica was either precipitated over the surface of MgO, or wet-kneaded with MgO to get mixed oxide catalysts. More active ETB catalysts were obtained if the MgO component has a higher specific surface area. XRD, EDS, XPS and acidity/basicity examinations showed that Mg atoms got incorporated into the silica phase, generating new Lewis acid surface sites. An amorphous MgO–SiO 2 mixed oxide preparation, having the highest surface Mg/Si ratio and atomic homogeneity, had the highest activity and 1,3-butadiene selectivity. The catalyst was obtained by hydrolyzation/condensation/precipitation of an Si,Mg–alkoxide solution within carbon mesopores and burning out the carbon/precipitate material. The catalytic ETB mechanism is discussed.

Keywords

C coupling, EDS, Lewis acid surface sites, Mg atoms, Mg/Si ratio, MgO, MgO component, Si, Si ratio, XPS, XRD, acetaldehyde, acid surface sites, active site, activity, area, atomic homogeneity, atoms, basic MgO, basic sites, butadiene, butadiene selectivity, butadiene yield, butanol, carbon mesopores, catalyst, catalytic selectivity, challenges, chemicals, components, concentration, consecutive reactions, conversion, conversion of ethanol, coupling, dehydration, dehydration activity, dehydrogenation, diethyl ether, effect, effects of chemicals, ethanol, ether, ethylene, examination, heterogeneity, high activity, high catalytic selectivity, high homogeneity, high specific surface area, homogeneity, hydrogenation/dehydrogenation, kind, main product, materials, mechanism, mesopores, mesoporous MgO, oxide catalysts, oxide preparation, phase, precipitate material, precipitation, preparation, product ethylene, products, ratio, reaction, selectivity, silica, silica phase, sites, solution, specific surface area, strength, structural heterogeneity, study, surface, surface area, surface of MgO, surface sites, transformation, yield

Funders

  • National Research, Development and Innovation Office
  • Hungarian Academy of Sciences
  • European Commission