Acid catalysts for biodiesel production

Apart from a few reports" on solid acid catalyzed esterification of model compounds, to our knowledge utilization of solid catalysts for biodiesel production from low quality real feedstocks have been explored only recently. 12-Tungstophosphoric acid (TPA) impregnated on hydrous zirconia was evaluated as a solid acid catalyst for biodiesel production from canola oil containing up to 20 wt % free fatty acids and was found to give ester yield of 90% at 200°C. Propylsulfonic acid-functionalized mesoporous silica catalyst for esterification of FFA in flotation beef tallow showed a superior initial catalytic activity (90% yield) relative to a... 

Kiss, A.A., Dimian, A.C., Rothenberg, A., Solid acid catalyst for biodiesel production-towards sustainable energy, Adv. Synth. Catal., 368, 75-81, 2006... 

Kiss, A.A. A.C. Dimian G. Rothenberg. Solid acid catalysts for biodiesel production—towards sustainable energy Synth. Catal. 2006,348, 75—81. 

Table 6.6 Recent heterogeneous solid acid catalysts for biodiesel production... 

Fu, X., et al., 2013. A microalgae residue based carbon solid acid catalyst for biodiesel production. Bioiesource Technology 146, 767—770. Available at http //www.sciencedirect. com/science/article/pii/S0%0852413011851 (accessed 22.06.14.). 

Melero, J.A., Iglesias, J., Morales, G., 2009. Heterogeneous acid catalysts for biodiesel production current status and future challenges. Green Chemistry 11 (9), 1285. Available at http //xlink.rsc.org/ DOI=b902086a (accessed 19.06.14.). 

Sani, Y.M., Baud, W.M.A.W., Abdul Aziz, A.R., 2014. Activity of solid acid catalysts for biodiesel production a critical review. Applied Catalysis A General 470, 140-161. 

Carbonized sugar derivatives are used as solid acid catalysts for the production of biodiesel fuel,349 and carbonized sucrose treated with ethylene and then pyro-lyzed provides materials used as hard-carbon anodes for lithium-ion batteries.439... 

Hung Su, C. (2013). Recoverable and reusable hydrochloric acid used as a homogeneous catalyst for biodiesel production. Applied Energy, 104, 503—509. 

Cardoso, A. L., S. C. G. Neves M. J. da Silva (2009) Kinetic study of alcoholysis of the fatty acids catalyzed by tin chloride (II) An alternative catalyst for biodiesel production. Energy Fuels, 23,1718-1722,ISSN 0887-0624. 

Fu, J., et al., 2015. Free fatty acids esterification for biodiesel production using self-synthesized macroporous cation exchange resin as solid acid catalyst. Fuel 154, 1—8. Available at http //www.sciencedirect.com/science/article/pii/S0016236115003440 (accessed 11.05.15.). 

Experiments showed that high methyl ester yields can be achieved with solid bases and super acids under moderate reaction conditions. The solid bases were more effective catalysts than the solid super acids. High stability can be achieved by an ordinary inexpensive preparation process, and the catalyst can be separated easily from the reaction products in the heterogeneous catalysis process. The costly catalyst removal process can be avoided compared with the homogeneous process. Therefore, the heterogeneous process using a solid catalyst should be more economical for biodiesel production. 

The production of biodiesel from low quality oils such as animal fats, greases, and tropical oils is challenging due to the presence of undesirable components especially FFA and water. A pre-treatment step is required when using such high fatty-acid feedstock. Generally, this esterification pre-treatment employs liquid sulfuric acid catalyst which must subsequently be neutralized and either disposed of or recycled. However, requirement of high temperature, high molar ratio of alcohol to FFA, separation of the catalyst, enviromnental and corrosion related problems make its use costly for biodiesel production. 

There is a real opportunity to reduce biodiesel production costs and environmental impact by applying modem catalyst technology, which will allow increased process flexibility to incorporate the use of low-cost high-FFA feedstock, and reduce water and energy requirement. Solid catalysts such as synthetic polymeric catalysts, zeolites and superacids like sulfated zirconia and niobic acid have the strong potential to replace liquid acids, eliminating separation, corrosion and environmental problems. Lotero et al. recently published a review that elaborates the importance of solid acids for biodiesel production. ... 

Recently, two processes for biodiesel production from crude tall oil have been proposed [48, 49]. They rely on the use of a homogeneous acid catalyst or of an acyl halide for the esterification reaction, but no information was given on the properties of the fuel obtained, particularly concerning the oxidative stability and conformity with European specification EN 14214 2003 for IV. 

Lipases (triacylglycerol hydrolases, EC 3.1.1.3) are enzymes that catalyze reactions such as hydrolysis, interesterification, esterification, alcoholysis, acidolysis, and aminolysis [1]. There is an increasing interest in the development of lipase applications to oleochemical transformations to obtain esters of long-chain fatty acids, as monoalkyl esters of fatty acids [2]. Utilization of lipase as a catalyst for the production of biodiesel, defined as a mixture of monoalkyl esters, is a clean technology due to its nontoxic and environmental fnendly nature, requiring mild operating conditions compared with chemical method [3]. 

The alkali process for biodiesel production can achieve high purity and yield of biodiesel in a short time. However, vegetable oils high in free fatty acids result in the production of soap and the loss of catalyst in the alkali process. To overcome this, the free tatty acids should be removed before the transesterification reaction. Because a homogeneous acid catalyst like sulfuric acid can not be recovered and is toxic, a heterogeneous acid catalyst can be used for the esterification of free fatty acids. Solid catalysts can be easily recovered after the reaction and reused [10-12]. 

Jothiramalingam, R. M. K. Wang (2009) Review of Recent Developments in Solid Acid, Base, and Enzyme Catalysts (Heterogeneous) for Biodiesel Production via Transesterification. Industrial Engineering Chemistry Research, 48, 6162-6172,ISSN 0888-5885. 

Saka, S., Isayama, Y, Ilham, Z. and Jiayu X. 2010. New process for catalyst-free biodiesel production using subcritical acetic acid and supercritical methanol. Fuel. 89(7) 1442-1446. 

Rao, B. V. S. K., Chandra Mouli,K., Rambabu,N.,Dalai,A. K., and Prasad, R. B. N. Carbon-based solid acid catalyst from de-oiled canola meal for biodiesel production. Catal Comm 14,20-26 (2011). 

Wu, H.T., Liu, Y.P., et al., 2014. In situ reactive extraction of cottonseeds with methyl acetate for biodiesel production using magnetic solid acid catalysts. Bioresource Technology 174, 182-189. 

Lipases are competitive catalysts in comparison with acids and aUcah because a wide variety of triglyceride substrates can be used for the enzymatic synthesis of biodiesel. An economically viable solution for biodiesel production is to use waste or useless fats as a triglyceride source (Gog et al., 2012). 

Numerous types of basic heterogeneous catalysts, such as alkahne earth metal oxide, anion exchange resins and alkali metal compounds supported on alumina or zeolite can catalyze various chemical reactions such as isomerization, aldol, Michael, and Knoevenagel condensation, oxidation and transesterification [1], Today considerable attention is devoted to the production of biodiesel (FAMEs) as an alternative for petroleum-derived diesel fuel. Biodiesel is synthesized by direct transesterification of vegetable oil or animal fat with a short-chain alcohol, viz. methanol, ethanol, and isopropanol in presence of an acid, base or enzymatic catalyst [2], Considering the advantages of solid base catalysts, for easy separation and recovery, reduced corrosion and environmental acceptance [1], many studies have been conducted on basic heterogeneous catalysts development for biodiesel production [3-13],... 

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