Life cycle environmental and cost implications of alternative feedstocks and conversion processes for isostearic acid production for pharmaceutical and personal care products

Authors: RIAZI, BAHAR - Drexel University; ZHANG, JIANWEI - South China University Of Technology; Yee, Winnie; Ngo, Helen; SPATARI, SABRINA - Drexel University

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2019
Publication Date: 8/9/2019
Citation: Riazi, B., Zhang, J., Yee, W.C., Lew, H.N., Spatari, S. 2019. Life cycle environmental and cost implications of alternative feedstocks and conversion processes for isostearic acid production for pharmaceutical and personal care products. ACS Sustainable Chemistry & Engineering. 7:15247-15258. https://doi.org/10.1021/acssuschemeng.9b02238.
DOI: https://doi.org/10.1021/acssuschemeng.9b02238

Interpretive Summary: Isostearic acid is an essential ingredient in many pharmaceutical and personal care products. In the industry, isostearic acid is predominately produced by a process called the tall oil process. Although this is a well-established process to efficiently produce isostearic acid, there is still a significant environmental concern with this technology because of the large amount of solid waste material generated in the old process which uses clay and it is discarded after each reaction. At ERRC, the researchers designed a process called the soybean oil process which overcomes this problem. The soybean oil process utilizes a reusable catalyst to make isostearic acid. By using a reusable catalyst, much less waste is formed, making it a more environmentally friendly process. The yield of isostearic acid from the recycled soybean oil process is comparable to the tall oil process. Additionally, the process cost model and life cycle assessment software further verified that the soybean oil process has significantly cut down the cost of disposal of waste and reduced the impact on climate change. This discovery reveals the potential of the new soybean oil process to be a suitable source for the isostearic acid production, from both environmental and economic aspects.

Technical Abstract: Bio-based lubricants have attracted wide interest as replacements for those derived from petroleum given their lower toxicity, biodegradability, and that they are made from renewable resources. Despite these qualities, some bio-based lubricants can have low operational lifetimes due to their poor oxidative and thermal stability. Isostearic acids, which are mixtures of isomers of saturated 18 carbon branched-chain fatty acids (sbc-FAs), can overcome these challenges owing to their excellent oxidative stability, low temperature properties and good lubricity, all of which make them ideal in pharmaceutical, personal care and cosmetic products. Bio-based lubricants have attracted wide interest as replacements for those derived from petroleum given their lower toxicity, biodegradability, and that they are made from renewable resources. Despite these qualities, some bio-based lubricants can have low operational lifetimes due to their poor oxidative and thermal stability. Isostearic acids, which are mixtures of isomers of saturated 18 carbon branched-chain fatty acids (sbc-FAs), can overcome these challenges owing to their excellent oxidative stability, low temperature properties and good lubricity, all of which make them ideal in pharmaceutical, personal care and cosmetic products. We investigated the life cycle environmental and economic impacts of isostearic acid production from a new process that uses soybean oil fatty acids (SOFA) and compare it to an existing industrial process that uses tall oil fatty acids (TOFA), a by-product of pulp and paper making. Chemical process simulation models were built based on experimental observations for SOFA and patent literature for TOFA. Multiple life cycle impact assessment metrics were estimated using two allocation methods and found to be slightly higher for SOFA compared to TOFA feedstocks. The potential climate change benefits were most significant for SOFA (1.9 to 3.7) compared to TOFA (0.9 to 1.5) kg CO2 eq./kg isostearic acid; however, results for both are low on a life cycle basis. Based on our techno-economic analysis, while isostearic acids produced from both SOFA and TOFA have higher production costs compared to the current market price, the coproducts made from each pathway render a profit of $1.83 and $3.51/KG, respectively. Based on our findings, we conclude that SOFA shows promise in terms of environmental and economic performance for expanding production of isostearic acid.