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A Comparative Study of Basic, Amphoteric, and Acidic Catalysts in the Oxidative Coupling of Methanol and Ethanol for Acrolein Production
Author(s) -
Lilić Aleksandra,
Wei Tiantian,
Bennici Simona,
Devaux JeanFrançois,
Dubois JeanLuc,
Auroux Aline
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201701040
Subject(s) - acrolein , crotonaldehyde , chemistry , catalysis , acetaldehyde , methanol , isothermal microcalorimetry , aldol condensation , inorganic chemistry , formaldehyde , adsorption , organic chemistry , ethanol , enthalpy , physics , quantum mechanics
Abstract The impact of acid/base properties (determined by adsorption microcalorimetry) of various catalysts on the cross‐aldolization of acetaldehyde and formaldehyde leading to acrolein was methodically studied in oxidizing conditions starting from a mixture of methanol and ethanol. The aldol condensation and further dehydration to acrolein were carried out on catalysts presenting various acid/base properties (MgO, Mg–Al oxides, Mg/SiO 2 , NbP, and heteropolyanions on silica, HPA/SiO 2 ). Thermodynamic calculations revealed that cross‐aldolization is always favored compared with self‐aldolization of acetaldehyde, which leads to crotonaldehyde formation. The presence of strong basic sites is shown to be necessary, but a too high amount drastically increases CO x production. On strong acid sites, production of acrolein and carbon oxides (CO x ) does not increase with temperature. The optimal catalyst for this process should be amphoteric with a balanced acid/base cooperation of medium strength sites and a small amount (<100 μmol g −1 ) of very strong basic sites ( Q diff >150 kJ mol −1 ).