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Published in Brajendra K. Sharma, Girma Biresaw, Environmentally Friendly and Biobased Lubricants, 2016
Kenneth M. Doll, Bryan R. Moser, Zengshe Liu, Rex E. Murray
Decarbonylation produces an unsaturated hydrocarbon as well as carbon monoxide through a mechanism that involves the coordination of a carboxylate moiety to the metal center of a catalyst in an oxidative addition. The first observation of this reaction, catalyzed by ruthenium and osmium, was made approximately 50 years ago [26]. Methodologies using palladium or rhodium catalysts to decarbonylate acids of 8 to 12 carbons were later developed [27,28] and, finally, extensions to biobased fatty acids were made [23,29–37]. Although catalytic, there are some drawbacks to this technology. First, for efficacy, the mechanism requires either the addition of or the in situ production of a hydrogen acceptor such as an anhydride. This disadvantage is best demonstrated by the example of the palladium-catalyzed decarbonylation of decanoic acid. Turnovers of up to 12,370 were observed when equimolar acetic anhydride was added, whereas less than 5 turnovers were noted without the anhydride [28].
Performance of NiMo-Al2O3 catalyst in biokerosene production via hydrocracking of dirty palm oil
Published in International Journal of Ambient Energy, 2022
Luqman Buchori, W. Widayat, Oki Muraza, Aji Prasetyaningrum, Jedy Prameswari, Aditya Widiyadi, Gema Adil Guspiani
The conversion of liquid products (biofuels) decreased with increasing concentrations of catalyst, hydrocracking tempera-ture and reaction times. However, the yield of biokerosene increased for all the parameters. From the catalyst concentration parameter test, the highest yield of biokerosene obtained was 52.76% with 0.04 g-catalyst/g-oil, 450°C and 1.5 h reaction time. While results from the hydrocracking temperature revealed that 550°C was the optimal temperature as it produced the highest biokerosene yield 53.77% with 0.01 g-catalyst/g-oil and 1.5 h reaction time. Results from the reaction time parameter test indicated that the optimal time was 3 h due to the highest biokerosene yield obtained, 56.38% with 0.01 g-catalyst/g-oil and 450°C temperature. The catalyst of NiMo-Al2O3 can simultaneously encourage decarboxylation, decarbonylation and hydrocracking reactions. The catalyst promotes all reactions both hydrotreating and hydrocracking simultaneously. Future works in this study should include a detailed understanding of process parameters such as hydrogen partial pressure and hydrogen/feed ratio to further obtain optimal operating conditions for biokerosene production.
Studying of different supported metal catalysts for bio-JET production
Published in Petroleum Science and Technology, 2022
Zoltán Eller, Zoltán Varga, Jenő Hancsók
Chen et al. studied the production possibilities of biojet fuel from waste cooking oil with hydrogenation too. They applied a pre-sulfided NiMo/Al2O3 catalyst and a Pd/C catalyst at various process parameter combinations. The experimental apparatus was a fixed bed reactor operated in continuous down-flow mode. The main products of the experiments were C15–C18 normal-paraffins. Based on the gas chromatographic analyses they found both hydrodeoxygenation, decarbonylation and decarboxylation reactions took place. Comparing the hydrodeoxygenation activity of Pd/C and NiMo/Al2O3 catalysts it was found that NiMo/Al2O3 had higher affinity for this reaction type (Chen and Wang 2019). The decarbonylation and decarboxylation reactions result products those contain one carbon atom less paraffin chain than the fatty acid part of the triglyceride feedstock does (Srivastava and Hancsók 2014). Eller, Varga, and Hancsók (2016) found hydrogen sulfide containing hydrogen gas could be used to maintain the nickel molybdenum/alumina catalyst in sulfide state. It is important from the aspect that this catalytic system can directly be applied in an existing crude oil refinery. CoMo/Al2O3 catalyst for hydrogenation of renewable sources was also studied.
Catalytic hydrothermal deoxygenation of the lipid fraction of activated sludge
Published in Biofuels, 2021
Ifeanyichukwu Edeh, Tim Overton, Steve Bowra
Renewable energy can be produced from sludge by processes including gasification, pyrolysis, incineration, combustion, supercritical water oxidation and anaerobic digestion, but these methods either produce harmful substances in addition to biofuels or have high capital and operational costs [10]. Therefore, there is a need to consider hydrocarbons/renewable diesel from the lipid fraction of activated sludge which has the potential to supplement the gaseous fuels or substitute for them. This type of diesel is like conventional petrodiesel and can be produced and transported using the existing refinery facilities [11, 12]. It is usually produced by removing oxygen atoms from fats and oils or fatty acids in the presence of a catalyst through hydrotreating [12–14]. A high partial pressure of H2 gas and catalysts such as CoMo/Al2O3 and NiMo/Al2O3 are usually required to remove oxygen in the form of water molecules [15–17]. On the other hand, renewable diesel can be produced without the addition of hydrogen through decarboxylation or decarbonylation. The former produces paraffinic hydrocarbon by removing the carboxyl group and oxygen atom (in form of CO2) in the fatty acids, and the latter produces olefinic hydrocarbon when the oxygen atom is removed as carbon monoxide [14, 17, 18]. These hydrocarbon molecules have a higher energy density than those produced through hydrotreating processes [19].