Influence of Catalyst Acid/Base Properties in Acrolein Production by Oxidative Coupling of Ethanol and Methanol

Abstract

Oxidative coupling of methanol and ethanol represents a new route to produce acrolein. In this work, the overall reaction was decoupled in two steps, the oxidation and the aldolization, by using two consecutive reactors to investigate the role of the acid/base properties of silica-supported oxide catalysts. The oxidation of a mixture of methanol and ethanol to formaldehyde and acetaldehyde was performed over a FeMoO catalyst, and then the product mixture was transferred without intermediate separation to a second reactor, in which the aldol condensation and dehydration to acrolein were performed over the supported oxides. The impact of the acid/base properties on the selectivity towards acrolein was investigated under oxidizing conditions for the first time. The acid/base properties of the catalysts were investigated by NH -, SO -, and methanol-adsorption microcalorimetry. A MgO/SiO catalyst was the most active in acrolein production owing to an appropriate ratio of basic to acidic sites.

A Comparative Study of Basic, Amphoteric, and Acidic Catalysts in the Oxidative Coupling of Methanol and Ethanol for Acrolein Production

“…Besides the processes that have been reported and applied to the industrial production of acrolein, continuous research has been undertaken to further develop more environmentally friendly methods starting from renewable feedstocks and to optimize the cost of the production process …”

“…In this respect, alcohol oxidative coupling of methanol and ethanol has been recently proposed and extensively studied as a potential method to replace the current fossil‐based production of acrolein from propylene . In this process, which takes place in the gas phase, acrolein can be directly synthesized in a single reactor, thus minimizing the investment costs …”

“…The first consists of the oxidation of methanol and ethanol to produce formaldehyde and acetaldehyde, then the second step implies the aldol condensation of formaldehyde and acetaldehyde and the dehydration of the two aldehydes to acrolein in the presence of oxygen. Knowing that aldolization reactions are generally catalyzed by basic and/or acidic sites, improved yield and selectivity towards acrolein should be obtained by enhancing the cross‐aldolization reaction on acid/base catalysts …”

“…This knowledge is necessary to understand how to improve acrolein production in a single reactor by using a mixture of FeMoO x redox catalyst and an aldolization acid/base catalyst. Therefore, as reported in a previous paper, the two‐step reaction has been performed in two separate consecutive reactors. The impact of the acid/base properties of aldolization catalysts on acrolein production has been investigated.…”

Regulating Aromatic Alcohols Distributions by Cofeeding Methanol with Ethanol over Cobalt‐Hydroxyapatite Catalyst

“…What's more, formaldehyde was also a primary product via the dehydrogenation of methanol, which acts as an active electrophile. [39] The yields of acetaldehyde and formaldehyde soon reached plateaus as they converted to 2butenal and acrolein via secondary self-or cross-condensation. The weight hourly space velocity of ethanol and methanol is 0.37 g C2H5OH ·g Cat.…”