Biodiesel feedstock

Transesterification of vegetable oils into the methyl ester fatty acid mixture (alcholysis) is achieved at similar reaction conditions for almost all oil feedstocks. Biodiesel is produced with the reaction of a vegetable oil with an alcohol (mostly methanol) in the presence of a catalyst (a strong base such as NaOH or KOH) at about 50°C temperature in a short time (shorter than 1 horn). The overall chemical reaction is presented in Scheme 1. 

Production costs for biodiesel from soybean oil exceeds 2.00 per gal ( 0.53 per 1), compared to 0.55 to 0.65 per gal ( 0.15 to 0.17 per 1) for conventional diesel. The main cost in biodiesel is in the raw material. It takes about 7.7 lb (3.5 kg) of soybean oil valued at about 0.25 per lb (0.36 per kg) to make 1 gal (3.81) of biodiesel. Waste oils, valued at 1 per gal ( 3.79 per 1) or less, have the potential to provide low feedstock cost. However, much waste oil" is currently collected, reprocessed as yellow and white greases, and used for industrial purposes and as an animal feed supplement. Production of biodiesel... 

The first engines invented by Rudolf Diesel ran on groundnut oil, but because of the advent of relatively cheap oil this type of biodiesel never became commercially viable. Since about 1930 the diesel engine has been refined and fine tuned to run on the diesel fraction of crude oil, which consists mainly of saturated hydrocarbons. For this reason the modem diesel engine cannot run satisfactorily on a pure vegetable oil feedstock because of problems of high viscosity, deposit formation in the injection system and poor cold-start properties. Today, however, environmental... 

Biodiesel is a fuel derived from renewable natural resources such as soybean and rapeseed and consists of alkyl esters derived from transesterification of triglycerides with methanol. In spite of all the advantages of biodiesel, such as low emissiotts, biodegradability, non-toxicity, and lubricity, the major hurdle in penetration of biodiesel is its high cost because of the expensive food grade refined vegetable oil feedstock. 

Biodiesel from High Free-Fatty Acid Feedstocks... 

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. ... 

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... 

Reports have shown solid catalysts for esterification of FFA have one or more problems such as high cost, severe reaction conditions, slow kinetics, low or incomplete conversions, and limited lifetime. We will present research describing our newly developed polymeric catalyst technology which enables the production of biodiesel from feedstock containing high levels (> 1 wt %) of FFAs. The novel catalyst, named AmberlysH BD20, overcomes the traditional drawbacks such as limited catalyst life time, slow reaction rates, and low conversions. 

Fatty acid methyl esters (FAME) are currently manufactured mainly by trans-esterification with an alcohol, using a homogeneous base catalyst (NaOH/KOH). Methanol is more suitable for biodiesel manufacturing, but other alcohols can in principle also be used, depending on the feedstock available. The... 

By 2006, the U.S. had 77 ethanol plants producing more than 3 billion gallons of ethanol per year. Canada produced an additional 60 million gallons. Corn was the feedstock in 62 of the 77 U.S. plants. Other feedstocks included seed corn, corn and barley, corn and beverage waste, brewery waste, cheese whey, corn and milo, corn and wheat starch, potato waste and various sugars. The U.S. had 11 additional plants under construction and 55 proposed. West Central Soy processes soybeans to a food grade oil. Alcohol and a catalyst are then used to produce biodiesel fuel and glycerin. 

BP has investments in an ethanol plant with DuPont and Associated British Foods. It is also investing in cellulosic ethanol research and developing jatropha as a biodiesel feedstock. BP and DuPont are planning a biobutanol demonstration plant and BP would like to eventually convert their ethanol plant to biobutanol production. BP has a 400 million investment with Associated British Foods and DuPont to build a bioethanol plant in the U.K. that may be converted to biobutanol. It has spent 500 million over 10 years at the Energy Biosciences Institute in California to research future biofuels and 9.4 million over 10 years to fund the Energy and Resources Institute (TERI) in India to study the production of biodiesel from Jatropha curcas. It also has a 160 million joint venture with D1 Oils to develop the planting of Jatropha curcas. 

In Europe, vegetable-oil-based fuels are mainly produced from rapeseed. In the USA, vegetable-oil-based fuels are mainly derived from soybeans. Another feedstock used in Europe and North America is sunflower seed. Most of the vegetable oil that is used as energy source for the generation of transportation fuel is converted to fatty acid methyl ester (FAME), often called biodiesel . 

Glycerol as a by-product from biodiesel production can be considered as a green chemical feedstock for subsequent catalytic transformation. In contrast to traditional petrochemical feedstocks, the present one is highly functionalized, its transformation requiring selective defunctionalization. 

The alternative fuels FT and DME fuels can be mannfactnred from natiual gas and are therefore not limited by feedstock availabiUty. Biodiesel on the other hand, is prodnced from vegetable (and some waste animal) oils whose supply for non-nutritional uses is presently quite limited. 

Table 4.6 Typieal properties of petroleum and biorenewable feedstocks and biodiesel...

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