Kinetic Study of Biodiesel Production from Chinese Tallow Tree Oil

Triadica sebifera, commonly known as the Chinese Tallow tree, was introduced into the United States from its native China as early as the 1700s. The fruit of the tree is a white seed that contains approximately 40% extractable material. This extract can be used to produce a number of valuable products, including biodiesel. The main benefit of choosing Triadica sebifera as a biodiesel feedstock is its high oil yield for a given plot of land. One hectare of Chinese Tallow trees can produce approximately 12,500 kg of seed, which could potentially yield 5,500 kg of oil. This amount of oil per hectare is almost 15 times that of soy oil, which is the most commonly used oil for making biodiesel in the United States. Also, the Chinese Tallow tree grows quickly in a variety of soils, making otherwise infertile land into a valuable source of revenue.

Unfortunately, the tree possesses invasive characteristics that allow it to overrun and easily displace native foliage in an uncontrolled environment. Despite its attractive appearance and valuable oil content, many regions have placed restrictions on the distribution of the tree, as it has invaded areas throughout the southeastern United States. Since the production of biodiesel from Triadica sebifera requires harvesting the oil-rich seeds, steps can and must be taken to prevent the spread of the seeds offsite.

Initial extractions have yielded between 40% and 45% extractable material. Gas chromatography with flame ionization detection has revealed that the oil from Triadica sebifera contains over 50% palmitic fatty acid, along with some oleic, linoleic and linolenic fatty acids. These fatty acids can be transesterified and processed to form biodiesel.

A study of the esterification reaction kinetics of converting the Chinese Tallow tree oil into biodiesel will be performed to determine the overall reaction order and rate constant. This information is necessary to engineer a biodiesel production facility that uses the seeds from the Chinese Tallow tree as a feedstock. Factors to be considered in the kinetics study include reaction temperature, mixing speed, ratio of methanol to oil, and reaction time. Also, the resulting biodiesel will be tested for compliance against the appropriate ASTM standards. If the biodiesel does not meet specifications, a study will determine the feasibility of blending the Chinese Tallow tree biodiesel with biodiesel from other feedstocks in order to make the resulting blend meet specifications.

Making biodiesel from Chinese Tallow oil would accomplish two major goals. The invasive Chinese Tallow tree would become a useful, commercially viable crop. Also, the biodiesel produced from Chinese Tallow would allow the United States to decrease its dependence on imported energy by displacing foreign petroleum with a domestic source of biodiesel that would not increase the necessary crop acreage.