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

Abstract

Aromatic alcohols, often used for the synthesis of plasticizers, coatings and pharmaceuticals, are currently produced from the oxidation of petroleum-derived aromatic hydrocarbons. Herein, we report a non-petroleum and environmentally friendly route for the production of aromatic alcohols: cofeeding methanol with ethanol over cobalt-hydroxyapatite catalyst, in which the distribution of aromatic alcohols products can be regulated by varying methanol pressure. Co species on hydroxyapatite can activate both methanol and ethanol to yield their corresponding aldehydes (formaldehyde and acetaldehyde). The followed cross-and self-condensations of aldehydes are catalyzed by hydroxyapatite to produce acrolein and 2-butenal, which are the key intermediates for the formation of aromatic oxygenates. The sequential cross-condensation and dehydrocyclization of acrolein and 2-butenal yield benzaldehyde, which is then hydrogenated to benzyl alcohol. The direct production of benzyl alcohol from methanol and ethanol could be regarded as a cutting-edge example, which ensures a promising route for sustainable aromatic alcohols production.

Direct synthesis of p-methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism

“…The synthesis of aromatic aldehydes from low-carbon aliphatic aldehydes (n ≤ 6) was explored under the optimal conditions ( Figure 5 ). When formaldehyde or acrolein were co-fed with acetaldehyde, a 10–12% selectivity of benzaldehyde was obtained, which was attributed to the complex network of competing reactions in these coupling-aromatization processes, leading to broad product distributions ( Zhou et al., 2020 ). Interestingly, p -MBA could be selectively synthesized from acetaldehyde or 2-butenal.…”

Catalytic Conversion of Ethanol to Oxygen-Containing Value-Added Chemicals

“…Notably, benzyl alcohol (BA−OH) is selectively formed on Co−HAP by co-feeding methanol with ethanol, and its selectivity increases with the partial pressure of methanol. 60 A maximum benzyl alcohol selectivity of ∼30% was achieved in the feed of 4 kPa methanol and 2 kPa ethanol at 325 °C. Detailed kinetic measurement indicates that high methanol pressure favors the formation of benzaldehyde and benzyl alcohols by facilitating the formation of enal intermediates with an odd carbon number.…”

Enhancing Ethanol Coupling to Produce Higher Alcohols by Tuning H2 Partial Pressure over a Copper-Hydroxyapatite Catalyst

“…The selectivity for aromatic oxygenates is as high as 40% over the Cu-HAP catalyst under a N 2 environment, which is in good accordance with our previous research. 30,32 Meanwhile, additional condensation products are 2-butenal, 2-butenol, and other unsaturated intermediates, resulting from acetaldehyde condensation (Table S2). 28 However, a further increase in hydrogen pressure would apparently shift the product selectivity from aromatic oxygenates to higher aliphatic alcohols, and barely any 2-MB-OH is detected when the H 2 partial pressure is above 20 kPa.…”