Catalytic advancements in carboxylic acid ketonization and its perspectives on biomass valorisation

Boekaerts, Bert; Sels, Bert F.

doi:10.1016/j.apcatb.2020.119607

Cited by 68 publications

(68 citation statements)

References 157 publications

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“…Both basic and acidic metal oxides such as ZrO 2 , TiO 2 , and CeO 2 as well as mixed metal oxide catalysts have been studied to improve the conversion of carboxylic acids and their selectivity to ketone. 26 − 29 In this context, the use of amphoteric catalysts can be the key in tuning the strength of acid–base sites available for ketonization. Pristine zirconia (monoclinic and tetragonal ZrO 2 ) has been investigated for the ketonization of acetic acid.…”

Section: Introductionmentioning

confidence: 99%

Role of Sulfation of Zirconia Catalysts in Vapor Phase Ketonization of Acetic Acid

et al. 2021

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The effect of the sulfation of zirconia catalysts on their structure, acidity/basicity, and catalytic activity/selectivity toward the ketonization of organic acids is investigated by a combined experimental and computational method. Here, we show that, upon sulfation, zirconia catalysts exhibit a significant increase in their Brønsted and Lewis acid strength, whereas their Lewis basicity is significantly reduced. Such changes in the interplay between acid–base sites result in an improvement of the selectivity toward the ketonization process, although the measured conversion rates show a significant drop. We report a detailed DFT investigation of the putative surface species on sulfated zirconia, including the possible formation of dimeric pyrosulfate (S 2 O 7 2– ) species. Our results show that the formation of such a dimeric system is an endothermic process, with energy barriers ranging between 60.0 and 70.0 kcal mol –1 , and which is likely to occur only at high SO 4 2– coverages (4 S/nm 2 ), high temperatures, and dehydrating conditions. Conversely, the formation of monomeric species is expected at lower SO 4 2– coverages, mild temperatures, and in the presence of water, which are the usual conditions experienced during the chemical upgrading of biofuels.

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Section: Introductionmentioning

confidence: 99%

Role of Sulfation of Zirconia Catalysts in Vapor Phase Ketonization of Acetic Acid

et al. 2021

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“…Ketonization is the first unit operation to elongate the carbon backbone of VFAs ( 14 , 22 ). Ketonization reacts two VFAs to produce a single ketone that is one carbon shorter than the sum of both acids and removes oxygen in the form of water and carbon dioxide ( 36 , 37 ). Ketonization of acetic acid to acetone has been commercialized ( 37 ), with longer chain acids actively researched for biofuel and biochemical applications.…”

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confidence: 99%

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Huq

Hafenstine

Huo

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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With the increasing demand for net-zero sustainable aviation fuels (SAF), new conversion technologies are needed to process waste feedstocks and meet carbon reduction and cost targets. Wet waste is a low-cost, prevalent feedstock with the energy potential to displace over 20% of US jet fuel consumption; however, its complexity and high moisture typically relegates its use to methane production from anaerobic digestion. To overcome this, methanogenesis can be arrested during fermentation to instead produce C2 to C8 volatile fatty acids (VFA) for catalytic upgrading to SAF. Here, we evaluate the catalytic conversion of food waste–derived VFAs to produce n-paraffin SAF for near-term use as a 10 vol% blend for ASTM “Fast Track” qualification and produce a highly branched, isoparaffin VFA-SAF to increase the renewable blend limit. VFA ketonization models assessed the carbon chain length distributions suitable for each VFA-SAF conversion pathway, and food waste–derived VFA ketonization was demonstrated for >100 h of time on stream at approximately theoretical yield. Fuel property blending models and experimental testing determined normal paraffin VFA-SAF meets 10 vol% fuel specifications for “Fast Track.” Synergistic blending with isoparaffin VFA-SAF increased the blend limit to 70 vol% by addressing flashpoint and viscosity constraints, with sooting 34% lower than fossil jet. Techno-economic analysis evaluated the major catalytic process cost-drivers, determining the minimum fuel selling price as a function of VFA production costs. Life cycle analysis determined that if food waste is diverted from landfills to avoid methane emissions, VFA-SAF could enable up to 165% reduction in greenhouse gas emissions relative to fossil jet.

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“…Despite the large number of studies focusing on surface ketonization published over the last three decades, both experimentally [21,22,24,25] and computationally [26,27], a general agreement on how the α-hydrogen is involved is still the subject of debate, and several mechanisms involving the participation of different intermediates have been proposed (e.g., via the direct concerted coupling of carboxylates [28], via ketene [29], via β-ketoacid [30], via carboxylic anhydride [31], or via a dianion interaction with a catalyst surface with a negatively charged α-carbon and a bidentate carboxylate group [21]). Nonetheless, several experimental evidence, carefully reviewed by Pham and co-workers [10] and by Sels and co-workers [32], suggest that the mechanism involving the formation of a β-ketoacid is the most probable one over the transition metal oxides.…”

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confidence: 99%

Evaluation of the Catalytic Activity of Metal Phosphates and Related Oxides in the Ketonization of Propionic Acid

Maron

Bellotti

Baldelli

et al. 2022

Sustainable Chemistry

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In recent years, the upgrading of lignocellulose bio-oils from fast-pyrolysis by means of ketonization has emerged as a frontier research domain to produce a new generation of biofuels. Propionic acid (PA) ketonization is extensively investigated as a model reaction over metal oxides, but the activity of other materials, such as metal phosphates, is mostly unknown. Therefore, PA ketonization was preliminarily investigated in the gas phase over both phosphates and oxides of Al, Zr, and La. Their catalytic activity was correlated to the physicochemical properties of the materials characterized by means of XRD, XRF, BET N2 porosimetry, and CO2- and NH3-TPD. Noteworthy, monoclinic ZrO2 proved to be the most promising candidate for the target reaction, leading to a 3-pentanone productivity as high as 5.6 h−1 in the optimized conditions. This value is higher than most of those reported for the same reaction in both the academic and patent literature.

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Catalytic advancements in carboxylic acid ketonization and its perspectives on biomass valorisation

Cited by 68 publications

References 157 publications

Role of Sulfation of Zirconia Catalysts in Vapor Phase Ketonization of Acetic Acid

Role of Sulfation of Zirconia Catalysts in Vapor Phase Ketonization of Acetic Acid

Toward net-zero sustainable aviation fuel with wet waste–derived volatile fatty acids

Evaluation of the Catalytic Activity of Metal Phosphates and Related Oxides in the Ketonization of Propionic Acid

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