Selective hydrogenation of oxalic acid to glycolic acid and ethylene glycol with a ruthenium catalyst
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Selective hydrogenation of oxalic acid to glycolic acid and ethylene glycol with a ruthenium catalyst Jackson H. S. Santos1 · Jadiete T. S. Gomes1 · Mohand Benachour1 · Eliane B. M. Medeiros1 · Cesar A. M. Abreu1 · Nelson M. Lima‑Filho1 Received: 8 July 2020 / Accepted: 17 August 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The hydrogenation of the oxalic acid was evaluated with a ruthenium micromesoporous catalyst (5 wt%/activated carbon, 710 m 2 g−1, 0.39 cm3 g−1), at 120 °C–150 °C under 80.0 bar in a slurry reactor, for the development of glycolic acid and ethylene glycol productions. The kinetic behavior of the process based on a surface mechanism was established according to the Langmuir–Hinshelwood approach. The mass balance equations fitted to the experimental data provided orders of magnitude for the specific reaction rates, reaching 1.93 × 10–1 h−1 for the hydrogenation of oxalic acid into glycolic acid at 130 °C and 2.51 × 10–2 h−1 for the production of volatile products at 150 °C. The kinetic selectivities under these conditions, 130 °C and 150 °C, were circa 70% for the production of glycolic acid, while for the volatile compounds was reached 87%. Keywords Hydrogenation · Ruthenium catalyst · Oxalic acid · Glycolic acid · Ethilene glycol · Selectivity
Introduction In the context of the development of innovative strategies for the sustainable production of chemicals and low emission fuels, the use of renewable raw materials is under focus [1]. A viable alternative is the catalytic hydrogenation of carboxylic acids [2, 3] which constitute intermediates group that provides the production of alcoholic compounds [4–6]. Glycolic acid, a key intermediate, and through its derivatives, with direct applications in the textile, food, pharmaceutical and plastics industries, can be produced through the catalytic hydrogenation of oxalic acid obtained by the oxidation of by-product of biodiesel production [1, 7]. * Cesar A. M. Abreu [email protected] 1
Laboratório de Processos Catalíticos (LPC), Universidade Federal de Pernambuco (UFPE), Av. Prof. Moraes Rego 1235, Cidade Universitária, Recife 50670‑901, Brazil
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Reaction Kinetics, Mechanisms and Catalysis
The noble metals ruthenium, platinum and palladium are very effective in the catalytic hydrogenation of carboxylic acids for alcohols, constituting catalytic systems as active phases or promoters on supports [8, 9]. Ruthenium has been highlighted as the active phase for the selective hydrogenation of various carboxylic acids and esters. The hydrogenation of lactic acid to propylene glycol was evaluated at 423 K and 13.6 MPa with a ruthenium catalyst, where a catalytic reaction mechanism served as basis for the proposal of Langmuir–Hinshelwood model [10]. The hydrogenation of maleic acid was performed at 543 K with RuRe catalyst to succinic acid, butyrolactone and tetrahydrofuran. The product selectivities were established through the kinetic rate equations for the reaction steps [11]. In the present study a rutheniu
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