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Journal ArticleDOI

Reaction pathways for the deoxygenation of vegetable oils and related model compounds.

01 Sep 2013-Chemsuschem (John Wiley & Sons, Ltd)-Vol. 6, Iss: 9, pp 1576-1594
TL;DR: It is shown that the type of catalyst has a significant effect on the deoxygenation pathway, that is, group 10 metal catalysts are active in decarbonylation/decarboxylation whereas metal sulfide catalyststs are more selective to hydrode oxygengenation.
Abstract: Vegetable oil-based feeds are regarded as an alternative source for the production of fuels and chemicals. Paraffins and olefins can be produced from these feeds through catalytic deoxygenation. The fundamentals of this process are mostly studied by using model compounds such as fatty acids, fatty acid esters, and specific triglycerides because of their structural similarity to vegetable oils. In this Review we discuss the impact of feedstock, reaction conditions, and nature of the catalyst on the reaction pathways of the deoxygenation of vegetable oils and its derivatives. As such, we conclude on the suitability of model compounds for this reaction. It is shown that the type of catalyst has a significant effect on the deoxygenation pathway, that is, group 10 metal catalysts are active in decarbonylation/decarboxylation whereas metal sulfide catalysts are more selective to hydrodeoxygenation. Deoxygenation studies performed under H2 showed similar pathways for fatty acids, fatty acid esters, triglycerides, and vegetable oils, as mostly deoxygenation occurs indirectly via the formation of fatty acids. Deoxygenation in the absence of H2 results in significant differences in reaction pathways and selectivities depending on the feedstock. Additionally, using unsaturated feedstocks under inert gas results in a high selectivity to undesired reactions such as cracking and the formation of heavies. Therefore, addition of H2 is proposed to be essential for the catalytic deoxygenation of vegetable oil feeds.
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Journal ArticleDOI
TL;DR: The application of zeolites, equipped with a variety of active sites, in Brønsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview.
Abstract: Increasing demand for sustainable chemicals and fuels has pushed academia and industry to search for alternative feedstocks replacing crude oil in traditional refineries. As a result, an immense academic attention has focused on the valorisation of biomass (components) and derived intermediates to generate valuable platform chemicals and fuels. Zeolite catalysis plays a distinct role in many of these biomass conversion routes. This contribution emphasizes the progress and potential in zeolite catalysed biomass conversions and relates these to concepts established in existing petrochemical processes. The application of zeolites, equipped with a variety of active sites, in Bronsted acid, Lewis acid, or multifunctional catalysed reactions is discussed and generalised to provide a comprehensive overview. In addition, the feedstock shift from crude oil to biomass involves new challenges in developing fields, like mesoporosity and pore interconnectivity of zeolites and stability of zeolites in liquid phase. Finally, the future challenges and perspectives of zeolites in the processing of biomass conversion are discussed.

568 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed the contributions relevant to each one of the aforementioned subjects for obtaining a synthetic picture concerning the progress pointed out so far and the future perspectives as well.
Abstract: The accumulation of greenhouse gases in the atmosphere resulting from the extensive use of fossil fuels and the depletion of oil reserves due to the increasing demands for energy compel the progressive replacement of fossil fuels by renewable energy sources among which biomass. Triglycerides-based biomass such as plant oils, animal fats, waste cooking and micro-algal oils should be upgraded by transesterification, cracking/hydrocracking and selective deoxygenation (SDO) to provide, respectively, biodiesel (fatty acid methyl esters), the so-called organic liquid product (mixture of hydrocarbons in the range of gasoline, kerosene and diesel) and green diesel (hydrocarbons in the diesel range). Problems related to the production, storage and use of the already produced biodiesel shifts the research to the second and third upgrading route. Intensive work in the last ten years has shown that the noble metals (mainly palladium) and the NiMo, CoMo and NiW sulphide catalysts supported on high surface area carriers, are promising concerning SDO for producing green diesel in the context of a stand-alone process of natural triglycerides. However, the high cost of the noble metal catalysts and the eventual S-contamination of the end product when using the aforementioned sulfided catalysts have rise intensive parallel research in the last three years for developing low cost Ni-based non-sulphide catalysts. The research effort in this area seems to focus on the following issues: (i) effect of supports, nickel loading and promoters on the catalytic performance of Ni-based non-sulphide catalysts, (ii) SDO pathways over these catalysts, (iii) effect of preparation method on their catalytic performance, (iv) comparison of nickel catalysts with other metallic and sulphide catalysts, (v) development of nickel phosphide catalysts, (vi) development of NiMo, CoMo or NiW non-sulphide catalysts (reduced, carbides, nitrides) and (vii) deoxygenation in low or no hydrogen containing atmosphere. In the present article we critically review the contributions relevant to each one of the aforementioned subjects for obtaining a synthetic picture concerning the progress pointed out so far and the future perspectives as well.

224 citations

Journal ArticleDOI
TL;DR: The rational control of the size, shape, composition and surface properties of nano-scale metal catalysts in the transformation of cellulose, chitin, lignin and lipids has been critically discussed.

175 citations

Journal ArticleDOI
TL;DR: In this paper, the deoxygenation of palm oil to green diesel was performed in a trickle-bed reactor over four γ-Al 2 O 3 -supported monometallic catalysts (Co, Ni, Pd, and Pt).

170 citations

Journal ArticleDOI
TL;DR: In this article, a comparison of carbon nanofiber-supported W2C and Mo2C catalysts on activity, selectivity, and stability for the hydrodeoxygenation of oleic acid to evaluate the catalytic potential for the upgrading of fat/oil feeds was performed.
Abstract: Group 6 (W, Mo) metal carbide catalysts are promising alternatives to hydrodesulfurization (NiMo, CoMo) catalysts and group 10 (Pd) type catalysts in the deoxygenation of vegetable fats/oils. Herein, we report a comparison of carbon nanofiber-supported W2C and Mo2C catalysts on activity, selectivity, and stability for the hydrodeoxygenation of oleic acid to evaluate the catalytic potential for the upgrading of fat/oil feeds. W2C/CNF was more selective toward olefins, whereas Mo2C/CNF was more selective toward paraffins. This was related to the hydrogenation activities of the respective metal carbides. Mo2C/CNF showed higher activity and stability compared with W2C/CNF.

153 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of the currently available information on the different process steps of the production process of bio-diesel from JCL, being cultivation and production of seeds, extraction of the oil, conversion to and the use of the biodiesel and the by-products.
Abstract: The interest in using Jatropha curcas L. (JCL) as a feedstock for the production of bio-diesel is rapidly growing. The properties of the crop and its oil have persuaded investors, policy makers and clean development mechanism (CDM) project developers to consider JCL as a substitute for fossil fuels to reduce greenhouse gas emissions. However, JCL is still a wild plant of which basic agronomic properties are not thoroughly understood and the environmental effects have not been investigated yet. Gray literature reports are very optimistic on simultaneous wasteland reclamation capability and oil yields, further fueling the Jatropha bio-diesel hype. In this paper, we give an overview of the currently available information on the different process steps of the production process of bio-diesel from JCL, being cultivation and production of seeds, extraction of the oil, conversion to and the use of the bio-diesel and the by-products. Based on this collection of data and information the best available practice, the shortcomings and the potential environmental risks and benefits are discussed for each production step. The review concludes with a call for general precaution and for science to be applied. (C) 2008 Elsevier Ltd. All rights reserved.

1,170 citations

Journal ArticleDOI
TL;DR: The main factors affecting transesterification are the molar ratio of glycerides to alcohol, catalyst, reaction temperature and pressure, reaction time and the contents of free fatty acids and water in oils as mentioned in this paper.

1,115 citations

Journal ArticleDOI
TL;DR: Most current research on oil extraction is focused on microalgae to produce biodiesel from algal oil, where algal-oil processes into biodiesel as easily as oil derived from land-based crops.

950 citations

Journal ArticleDOI
TL;DR: In this paper, the authors discuss in a general and comparative fashion aspects such as fuel production and energy balance, fuel properties, environmental effects including exhaust emissions and co-products, and what the effect of production scale may be.

842 citations

Journal ArticleDOI
TL;DR: In this article, a novel method for production of diesel-like hydrocarbons via catalytic deoxygenation of fatty acid is discussed, where the model compound stearic acid is deoxgenated to heptadecane.
Abstract: A novel method for production of diesel-like hydrocarbons via catalytic deoxygenation of fatty acid is discussed. The model compound stearic acid is deoxygenated to heptadecane, originating from the stearic acid alkyl chain. The deoxygenation reaction is carried out in a semibatch reactor under constant temperature and pressure, 300 °C and 6 bar, respectively. A thorough catalyst screening was performed to obtain the most promising metal and support combination. The catalysts were characterized by N2-physisorption, CO-chemisorption, and temperature-programmed desorption of hydrogen. A highly active and selective in the deoxygenation reaction of stearic acid carbon supported palladium catalyst converted stearic acid completely with >98% selectivity toward deoxygenated C17 products.

599 citations