Techno-economic analysis of an improved process for producing saturated branched-chain fatty acids

Authors: Ngo, Helen; Yee, Winnie; McAloon, Andrew; Haas, Michael

Submitted to: Journal of Agricultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2014
Publication Date: 9/15/2014
Publication URL: http://handle.nal.usda.gov/10113/60661
Citation: Lew, H.N., Yee, W.C., Mcaloon, A.J., Haas, M.J. 2014. Techno-economic analysis of an improved process for producing saturated branched-chain fatty acids. Journal of Agricultural Science. 6(10):158-168.

Interpretive Summary: Biobased products have many advantages over petroleum-based products, such as biodegradability. Unfortunately, the high cost of the finished products has limited their production and use. To overcome this obstacle, research efforts on the development of economically feasible technologies to make these products are necessary, and these technologies must be competitive with petroleum-based processes. Commercial isostearic acids (IA) are unique biobased chemicals because of their excellent low temperature and lubricant properties. The existing technology for IA production is neither efficient nor cost effective as it gives low yields of the desired IA products. At ARS, an efficient process has been developed to give high yields of the IA product and low formation of undesirable byproducts. In this paper, a process model of this new method was constructed, allowing calculation of the economic feasibility of the technology. The calculation indicated that the new process is a lower cost alternative to previously described method for the production of IA. This work will be of great interest to manufacturers of biobased lubes and greases.

Technical Abstract: Vegetable oils provide a source of environmentally desirable lubricants, but they are not widely utilized because of their poor oxidative stability. Branched-chain fatty acid isomers are desirable products because they have excellent thermostabilities and lubricities when compared to the parent vegetable oil. This paper describes the construction and evaluation of a techno-economic model for industrial scale (5,089,626 kg branched-chain product annually) implementation of a fatty acid isomerization process catalyzed by H-Ferrierite zeolite. As opposed to prior analyses, the process modeled here included a regeneration protocol that allowed reuse of the catalyst. The model targeted 19 reuses of the catalyst, with a >80% yield of the branched-chain fatty acid product at each reaction. Data to guide the modeling was produced by conducting a series of 20 isomerizations, each reaction containing 50 g of oleic acid, 2.5 g of H-Ferrierite zeolite, small amounts of water and triphenylphosphine incubated at 260 oC for 4 hours. According to the techno-economic studies, the difference in the unit production costs between various catalyst reuse models is substantial, falling with repeated reuse of the catalyst. The saving generated by reuse of the catalysts are especially striking when compared to a previously reported model (Ngo, H.L., Yee, W.C., McAloon, A.J., Haas, M.J. Process and cost modeling of saturated branched-chain fatty acid isomer production. I&EC Research, 2012, 51, 12041-12045) in which catalyst was regenerated and used a total of 5 times.