Life Cycle Environmental and Cost Implications of Isostearic Acid

Subscriber access provided by Nottingham Trent University

Article

Life Cycle Environmental and Cost Implications of Isostearic Acid Production for Pharmaceutical and Personal Care Products Bahar Riazi, Jianwei Zhang, Winnie Yee, Helen Ngo, and Sabrina Spatari ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.9b02238 • Publication Date (Web): 09 Aug 2019 Downloaded from pubs.acs.org on August 13, 2019

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 49 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Life Cycle Environmental and Cost Implications of Isostearic Acid Production for Pharmaceutical and Personal Care Products Bahar Riazi1#, Jianwei Zhang2,3#, Winnie Yee2, Helen Ngo2, Sabrina Spatari*1,4 1 Drexel University, Department of Civil, Architectural, and Environmental Engineering, 3141 Chestnut Street, Philadelphia, PA, USA 2 USDA, ARS, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA, USA 3 School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong, China 4 Faculty of Civil and Environmental Engineering, Technion – Israel Institute of Technology, Haifa, Israel

*Corresponding author: [email protected], [email protected]

#Contributed equally to research modeling

Keywords: Techno economic analysis, Life cycle assessment, Bio-lubricants, Isomers, Fatty acids, Green chemicals

1 ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 2 of 49

Abstract Like many specialty chemicals used in pharmaceutical, personal care and cosmetic products, few life cycle inventory data are available to describe the synthesis of isostearic acids (IA). We investigate the cradle-to-gate life cycle environmental and economic performance of IA production from soybean oil and tall oil, both renewable resources, using chemical process simulation models that integrated experimental measurement and data from patent literature. Multiple life cycle impact assessment metrics were estimated where the difference in the climate change impact was most significant for the soybean oil (1.9 to 3.8) compared to tall oil (1 to 1.5) kg CO2 eq./kg IA process; however, results for both are low on a life cycle basis compared to synthetic lubricants. Considering the value-added from coproducts, the unit production cost for the soybean oil pathway was lower than that of tall oil but its profit and return-on-investment were also lower. Despite these differences, soybean oil remains a promising feedstock for expanding “green” IA production. Examining hotspots along the soybean oil-to-IA life cycle, we identify strategies for environmental and economic improvement at the product conversion and recovery stages. We discuss the challenges of predicting the environmental performance of specialty chemicals and new conversion processes and conclude that detailed process modeling like that performed herein is in many cases necessary for capturing environmental tradeoffs.


Page 3 of 49 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Introduction The vast majority of lubricants available on the market are produced from petroleum resources,1 whose production (along its supply chain) and use contribute to leakages to the environment. In particular, mineral oils derived from petroleum resources that contain sulfur, nitrogen, and metals could pose impacts to groundwater reserves and ecosystems due to their poor biodegradability and toxicity.

1-3

Moreover, petroleum-based lubricants have a wide range of

greenhouse gas (GHG) emissions ranging from 0.94 to 3.15 kg carbon dioxide equivalent (CO 2 e) per kg of lubricant over their production cycle depending upon the application. For example, the GHG intensity of premium lubricants used in automotive power steering can be as high as 3.1 kg CO 2 e per kg of lubricant.5 At the end of their use cycle, due to their toxicity and difficulty in handling, used lubricating oils can release an additional fossil-based 1.3-3.4 kg CO 2 e per kg of lubricant to the atmosphere depending on how they are managed either by recycling or by energy recovery.6-7 Bio-based lubricants, such as isostearic acids, may be environmentally preferable to petroleum-based lubricants given that they are biodegradable, made from renewable resources, and release biogenic carbon if combusted or when decomposed at end-of-life.1, 8 Isostearic acid is a mixture of saturated methyl branched-chain fatty acid isomers that is a liquid at room temperature.8 Due to their excellent oxidative stability, low temperature properties, good lubricity, and high viscosity index number, 45,000 tons of isostearic acids9, with expanding production capacity10, are consumed globally mainly as intermediates in the lubricant industry to produce numerous products including cosmetics, slip additives, anti-blocking agents, and emollients.8, 11-12 Based on recent market research reports, about 70%-80% of isostearic acid was used for chemical esters (mostly for producing personal care) and cosmetic products. Isostearic acid is typically



Page 4 of 49

produced from plant oils.1 Unprocessed plant oils such as soybean oil are promising sources of renewable lubricants due to their ease of extraction, low process energy requirement, as well as their biodegradability. 2-3, 7, 13 However, owing to their poor oxidative and thermal stability these oils can have low operational lifetimes.2-3, 13 Conversion to more stable compounds can help prolong the operational life of lubricants. Isostearic acid, one such stable lubricant, can be used in multiple value-added products, particularly for personal care, cosmetic and pharmaceutical products.14-15 Life cycle assessment (LCA) is a systematic method for comparing the environmental tradeoffs of products, processes, and activities.16 In recent years, LCA has been used to evaluate the production of value-added products such as fuels, chemicals, and polymers from biomass and novel technologies to compare them with existing products on the market.17-23 Combined with technoeconomic analysis (TEA), LCA enables a systematic evaluation of the environmental, economic and technological feasibility of new products and processes relative to their petroleum-based counterparts.24-28 Hence, evaluating both the economic (through TEA) and life cycle environmental impacts of chemicals from renewable feedstocks can provide insight into the economic feasibility as well as environmental footprint and potential risk of such products.29-30 Developing life cycle inventory (LCI) profiles for specialty chemicals presents many challenges owing to the vast quantity of chemicals that are manufactured and needed to synthesize a given chemical. Commercial LCA databases have a finite number of LCI data for chemicals. To address this and other challenges in prospective LCA, frameworks31, hierarchies and guidelines32 and a variety of methods, have been developed to approximate the LCI of specialty chemicals using CAS number, chemical composition, molecular weight, and chemical structure relationships. For example, Eckelman33 developed a method for assigning inherent toxicity to synthesized


Page 5 of 49 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


chemicals, Wernet et al.34-35 and Song et al.36 used artificial neural network (ANN) methods to approximate select life cycle impact assessment (LCIA) metrics for chemicals and Hou et al.37 used data mining techniques to estimate missing unit process data required for LCA. Cashman et al.38 also used data mining techniques rather than chemical process simulation and emission modeling to estimate uncontrolled air emissions, which Smith et al.39 argue adds to the list of chemical species emitted from a process without having knowledge of the technology; they circle back to process modeling as a means of controlling technology-specific data quality for a given chemical process in spite of the complexity involved in simulation. Approximations using machine learning, though valuable given the possibility of predicting results without undertaking time-intensive and costly experiments and chemical process simulations, are in most cases blackbox approximations that do not allow for evaluating alternative process and operational configurations that lead to understanding the sensitivity and variability of process parameters on life cycle and cost outcomes for a given product system. There is much value in combining LCA and TEA methods for early stage technology since these methods enable predicting both environmental impact and costs. Moreover, others posit that simulated uncertain parameters will be closer to actual industrial values given the ability of the process simulation to adjust such values based on other known parameters.40 While available chemical process simulation software are valuable tools, relying only on their results might lead to not taking into account all emissions during the process.41 To address this, Villalba et al. developed a framework based on building modules to integrate reaction emissions within the process simulation software.42 Also, while incorporating computer-aided process simulations and LCA provides comprehensive information to examine the process at the plant level43, a general flexible framework without the need for use of time-consuming process simulations can help policy makers screening a large number of



Page 6 of 49

emerging technologies to make decision at early stages.44 Process modeling and simulation, while it involves much computation, enables considering yield, side reactions, selectivity, equipment selection, consideration of chemical properties that are pressure and temperature dependent, heat integration, as well as other chemical process considerations32 that directly impact both LCA and TEA estimations. We apply LCA with TEA to the synthesis of isostearic acid and discuss the implications of benchmarking process models with ANN approaches. Prior LCA research has evaluated bio-lubricants made from renewable feedstock sources for metalworking fluids, automotive base oils, and hydraulic systems.7, 45-48 Moreover, much LCA research on soybean oil as a renewable feedstock has focused on its conversion to biodiesel as a transportation fuel49-55 and in some cases its direct use for operating off-road equipment56, all of which show a reduction in GHG emissions compared to petroleum-based diesel. However, soybean oil can be used as a resource to produce high-value products including polymers,57-58 and it can also be converted to lubricants such as isostearic acid.1 An important market for bio-based feedstocks is the personal care, pharmaceutical, and cosmetics markets, which more often seek to use green chemicals evaluated using LCA.59-61 Therefore, our objective is to evaluate the environmental and economic performance of bio-based isostearic acid production from soy oil, a renewable feedstock that has already been tested at laboratory scale1, 12 for conversion to high performance lubricants used in the personal care products industry. We also benchmark soybean oil fatty acids (SOFA) from soybean oil against tall oil fatty acid (TOFA), a by-product of pulp and paper manufacture that is currently the main renewable source of isostearic acid production.14, 62

Cashman et al.63 evaluated the life cycle greenhouse gas emissions for fuels and chemical

products from TOFA but to date no prior study has examined multiple LCIA metrics for isostearic acid produced from TOFA. Soybean oil is co-produced with soy meal, which is used as animal


Page 7 of 49 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


feed, and can be used to produce high performance isostearic acids with viscosity indexes higher than those of mineral oils, and thus may be a suitable feedstock for the expanding isostearic acid market. Unlike plant oils like palm oil, which can be used as feedstock for lubricant production, but currently contribute to deforestation in Southeast Asia64, land use change (LUC)-related GHG emissions and loss of species diversity, SOFA and TOFA feedstocks do not introduce major LUCrelated environmental impacts due to continued cultivation on existing agricultural land (SOFA) or being an industrial residue (TOFA). Methods We apply LCA and TEA to evaluate the environmental and economic implications of isostearic acid produced from SOFA (origin is soybean oil) and TOFA. We use mass and energy balances generated from chemical process simulations modeled based on experimental observations and build a LCI model following the International Organization for Standardization (ISO 2006).16 The functional unit is defined as 1 kg of isostearic acid. We apply the ReCiPe LCIA method to evaluate midpoint (hierarchist) environmental burdens for different feedstocks and conversion processes for producing isostearic acid.65-66 ReCiPe LCIA metrics provide a holistic approach to compare the “level of greenness”67 of isostearic acids produced from alternative feedstocks. These metrics have been applied in both Europe and North America to evaluate the life cycle environmental impacts of a wide range of product and engineering designs, including, green infrastructure68, urban water infrastructure69, photovoltaics70-71, chemicals72-74, pharmaceuticals75-77, and nanotechnology78-79. Our goal is to use select ReCiPe LCIA metrics to evaluate new production routes for bio-based isostearic acids within a prospective LCA framework. A set of midpoint LCIA metrics (Table 1) were chosen for evaluation in this study based on their importance as decision metrics for using bio-based feedstocks in pharmaceutical and personal care products, which relate



Page 8 of 49

to energy and climate change, human toxicity potential, consumption and degradation of renewable resources (water), environmental impact (ozone depletion and terrestrial acidification) and land transformation.17, 29, 67, 73, 80-81 We simulated the conversion of SOFA from soybean oil and TOFA to isostearic acid and coproducts for facilities with a plant capacity of 4.5 million kg year-1 (10 × 106 lb year-1) of isostearic acid production using SuperPro Designer82 software. The input parameters are based on experiments for SOFA, patent literature for TOFA, academic literature and information provided by industrial experts and equipment suppliers.9, 83 We use TEA based on our SuperPro Designer process simulation models to estimate the production cost and profit for the production of 1 kg isostearic acid from SOFA and TOFA; estimate the payback time and return on investment of the projected bio-plants; and we examine the sensitivity of key cost metrics due to variation in historic soybean oil market price and variation in tall oil market price. Soybean oil has varied between $0.63 to $1.21 per kg over the last decade84. An average market price for tall oil price was varied by +/-20% due to limited market price data on the commodity. Table 1. List of chosen environmental impact categories using ReCipe midpoint (H) method Impact category

Unit

Climate Change

kg CO 2 eq.

Ozone depletion

kg CFC 11 eq.

Fossil depletion

kg oil eq.

Human toxicity

kg 1,4-dichlorobenzene eq.

Water depletion

m3

Marine eutrophication

kg N eq.

Terrestrial acidification

Kg SO 2 eq.

Natural land transformation

m2


Page 9 of 49 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


SOFA-based isostearic acid Production of isostearic acid coproduced with dimer acid and stearic acid is modeled as a cradle-to-gate process that includes soybean farming, soybean oil extraction where the oil is coproduced with soybean meal, hydrolysis, isomerization, hydrogenation and product recovery (Figure 1). The dimer acid co-produced in the SOFA process is not distilled dimer acid and it contains

Life Cycle Environmental and Cost Implications of Isostearic Acid

Recommend Documents