The most prevalent process for the production of biodiesel-or chemically, the conversion of triglycerides to the corresponding methyl ester-is transesterification by homogeneous alkaline catalysis. Catalysts that can be used in this process include caustic soda (sodium hydroxide), caustic potash (potassium hydroxide) and sodium methylate.

Sodium methylate has become the catalyst of choice for modern large-scale biodiesel production accounting for more than 70 percent of the biodiesel produced in North America. All major technology providers including Lurgi PSI, Desmet Ballestra and Crown Iron Works offer biodiesel process technologies and plant designs that utilize sodium methylate. In addition, an increasing number of biodiesel producers are switching to superior water-free sodium methylate solutions from traditional solid catalysts like sodium or potassium hydroxide.

What is sodium methylate?

Sodium methylate is referred to by many names including alcoholate, methoxide and sodium methoxide. It is a versatile chemical reagent used for many decades in various industries to produce high-value end products like pharmaceuticals, food ingredients, pigments and crop protecting agents. In recent years, the production of biodiesel has become an exciting, new and fast-growing application for sodium methylate. In the future, biodiesel production will have a significant share of the overall sodium methylate demand worldwide. BASF is one of the world's leading providers of high-quality alcoholates, such as sodium methylate, and produces the catalyst in a dedicated world-scale facility in Ludwigshafen, Germany. From there, the corporation ships the product all over the world-from Europe to the United States to Asia to Australia.

In addition to its production facility in Germany, BASF operates large storage facilities in all major regions of the world. Typical packaging for sodium methylate solution can include drums, totes, isocontainers, bulk trucks and railcars. The company also provides customized and innovative customer service and logistical solutions for biodiesel plants worldwide.

Safe handling of sodium methylate

Sodium methylate is typically supplied either as a solid (crystal) or as solutions in methanol. For biodiesel production, solutions in a concentration range of 25 percent to 30 percent have proven most advantageous. Safety and handling practices for sodium methylate solutions are very similar to safety and handling practices for methanol. Like methanol, sodium methylate solution is flammable and is handled safely by many people on a daily basis. When handling sodium methylate, it is important to remember that:

• Sodium methylate solution needs to be stored in a dry place.


• Bulk storage of sodium methylate solution should conform to the general requirements for methanol.


• Sources of ignition like sparks, flames, heat and electrical discharges should be avoided.

For any questions or concerns, the sodium methylate manufacturer should be consulted and/or the material safety data sheet should be reviewed. In addition, BASF has a product stewardship group that can answer safety and handling questions, and provide training to personnel that handle this catalyst.

High yields, efficient, simple processing

Sodium methylate functions as a catalyst to accelerate the biodiesel chemical reaction process by reducing the energy needed to initiate the reaction. It is successfully used in large-scale production facilities for all major feedstocks like virgin vegetable oils, animal fat and/or yellow grease. The major advantage of sodium methylate is the virtually water-free character of the catalyst solution. This results in higher yields, lower purification costs and more consistent biodiesel quality. When mixing traditional hydroxides with methanol, hazardous solid handling is inevitable, and as a result, water is generated that will initiate unwanted side reactions.

Table 1 highlights the main benefits of using sodium methylate instead hydroxides. These advantages make it obvious why most producers rely on sodium methylate, especially since it has proven its favorable effects over the hydroxides in many reference plants. A 2004 NREL study, titled Biodiesel Production Technology, compared several catalysts including sodium methylate. The report concluded that sodium methylate, as a 25 percent solution in methanol, was a more powerful catalyst on a weight basis than a mixture of caustic soda and methanol. Another study titled Integrated Biodiesel Production: A Comparison of Different Homogeneous Catalysts Systems, conducted by the University of Madrid in 2004, found similar results. That study compared the effectiveness of sodium methylate, sodium hydroxide and potassium hydroxide in a reaction of sunflower oil and methanol. Table 2 summarizes the results.

Although all of the catalysts produce a high-quality biodiesel product, the sodium methylate catalyst provides the highest yield of biodiesel. Since feedstock costs of the vegetable oil or other triglyceride sources account for most of the variable cost of biodiesel production (up to 90 percent), a higher yield of a few percent usually translates into substantial savings that more than compensate for the higher catalyst cost.

To obtain more information about the BASF portfolio of biodiesel production catalysts, visit www.basf.com/alcoholates.

Susan Jackson is BASF product manager for standard alcoholates. Reach her at jacksos1@basf-corp.com or (724) 538-1374.