Catalytic Developments in the Epoxidation of Vegetable Oils and the Analysis Methods of Cite This: RSC Adv.,2019,9,38119 Epoxidized Products
Total Page:16
File Type:pdf, Size:1020Kb
RSC Advances View Article Online REVIEW View Journal | View Issue Catalytic developments in the epoxidation of vegetable oils and the analysis methods of Cite this: RSC Adv.,2019,9,38119 epoxidized products Phyu Thin Wai, Pingping Jiang, * Yirui Shen, Pingbo Zhang, Qian Gu and Yan Leng Functionalization of vegetable oils (VOs) including edible, non-edible, and waste cooking oil (WCOs) to epoxides (EVOs) is receiving great attention by many researchers from academia and industry because they are renewable, versatile, sustainable, non-toxic, and eco-friendly, and they can partially or totally replace harmful phthalate plasticizers. The epoxidation of VOs on an industrial scale has already been developed by the homogeneous catalytic system using peracids. Due to the drawbacks of this method, other systems including acidic ion exchange resins, polyoxometalates, and enzymes are becoming alternative catalysts for the epoxidation reaction. We have reviewed all these catalytic systems including Received 31st July 2019 their benefits and drawbacks, reaction mechanisms, intensification of each system in different ways as Accepted 9th October 2019 Creative Commons Attribution-NonCommercial 3.0 Unported Licence. well as the physicochemical properties of VOs and EVOs and new findings in recent years. Finally, the DOI: 10.1039/c9ra05943a current methods including titrimetric methods as well as ATR-FTIR and 1H NMR for determination of rsc.li/rsc-advances conversion, epoxidation, and selectivity of epoxidized vegetable oils (EVOs) are also briefly described. 1. Introduction controlled plasticizer (along with DBP and BBP). In March 2015, the European Commission added DEHP/DOP as well as di Although phthalate plasticizers have been used for many normal butyl phthalate (DBP), diisobutyl phthalate (DIBP), and decades in poly(vinyl chloride) (PVC) insulation and jacketing of butylbenzyl phthalate (BBP) to Annex II of RoHS. Thus, their This article is licensed under a cables, several commonly utilized phthalates have been recog- presence was stipulated to not exceed 0.1% in electrical and nized or suspected to be harmful, of which diethylhexyl electronic equipment placed on the European Economic Area phthalate (DEHP)/dioctyl phthalate (DOP) is the most rigorously (EEA) market, with effect from July 22, 2019 (or July 22, 2021, for medical devices, or medical or industrial controls and instru- Open Access Article. Published on 21 November 2019. Downloaded 9/30/2021 2:11:46 PM. Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of ments). A er July 2019, DEHP/DOP, DBP, DIBP, or BBP over Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China. 0.1% w/w in any homogeneous plastic or rubber will be RoHS E-mail: [email protected] Phyu Thin Wai was born in Prof. Dr Pingping Jiang was born Taungdwingyi City, Magway in Wuxi City, Jiangsu Province of Division of Myanmar. She China. He has obtained received her Master's degree in a Master's degree from Beijing 2007 from Yadanabon Univer- University of Chemical Tech- sity, Mandalay Division of nology and doctoral degree from Myanmar. Aerwards she joined East China University of Science as an assistant lecturer at the and Technology. He has also same university in 2009. At been to the University of South present, she is a doctoral candi- Florida, U.S.A. as a senior date at School of Chemical and research scholar. He is now Material Engineering in Jian- working in the School of Chem- gnan University. Her current ical and Material Engineering, research area is the catalytic developments in the epoxidation of Jiangnan University as a doctoral Tutor and academic leader of the vegetable oils and their derivatives. research team of Advanced Functional Material and Environ- mental Additives. He has been engaged in the research of ne organic synthesis and industrial catalytic application. This journal is © The Royal Society of Chemistry 2019 RSC Adv.,2019,9, 38119–38136 | 38119 View Article Online RSC Advances Review non-compliant (2021 for certain types of equipment).1 Because annual production of WVO is over 700 000 tonnes in the EU and of these severe issues, nding an alternative to toxic phthalate 4.5 million tonnes in China.12 These are attractive sources for plasticizers has become an important concern. making valuable products. Vegetable oils (VOs) composed predominantly of triglycer- By using proper reagents and catalysts, vegetable oils can be ides are playing an important role in the chemical industry, modied into alternative compounds via different reactions, thanks to their inherent biodegradability, accessibility, and such as epoxidation, hydroxylation, carboxylation, halogena- versatile modications as well as environmental issues and tion, hydrogenation, and oxidation.13 Among many functional- scarcity of petroleum sources.2 According to Statista, vegetable ization reactions of vegetable oils, the epoxidation of vegetable oil production is growing constantly and amounted to some oils is a renowned reaction, with patented applications since 203.83 million metric tons worldwide in 2018–2019.3 Vegetable 1946 and nowadays, it is becoming more and more popular due oils are also extensively utilized as precursors for the production to the high reactivity of the epoxy group.14 of lubricants, cosmetic products, surfactants, paint formula- However, the unsaturated sites within the fatty acids of tion, coatings, and resins.4 Waste vegetable oils (WVO) as well as vegetable oils may be less prone to epoxidation in comparison non-edible oils such as tall oil,5 jatropha oil,6 and cottonseed with terminal double bonds of short-chain olens.15 Moreover, 7 oil have become alternative promising candidates of triglycer- it was reported that H2O2 and oil or fat in the absence of cata- ides that are yet to be profoundly exploited because they have lysts did not show any apparent reactivity, so an oxidant was the potential to meet the requirements of low price materials crucial to shi the active oxygen from the aqueous to the oil without having the need for competition with food crops.8 phase.16 Besides, the improper disposal of WVO results in oxygen In addition to H2O2, organic hydroperoxides (e.g., TBHP) are depletion that severely harms aquatic life; technological valo- also appropriate oxidants for epoxidation reactions catalyzed by rization of WCO can solve such a serious environmental various transition metal compounds such as Mo15 and Ti.17 issue.9,10 However, appropriate collection management system These metals with strong Lewis acid character are active cata- Creative Commons Attribution-NonCommercial 3.0 Unported Licence. and analysis of the quality of WCO should be done to meet the lysts that act as relatively weak oxidants. In particular, requirements for valorization.11 It is approximated that the molybdenum-containing complexes have been extensively Yirui Shen received her Bache- Qian Gu received her Bachelor's lor's degree from Jiangnan degree from Suzhou University University in China in 2014. of Science and Technology in Now, she is a doctoral candidate China in 2013 and obtained her This article is licensed under a in Jiangnan University. Her MS degree from Shanghai Insti- research mainly focuses on the tute of Technology in China in design and preparation of 2016. Now, she is a doctoral heterogeneous catalysts applied candidate in Jiangnan Univer- Open Access Article. Published on 21 November 2019. Downloaded 9/30/2021 2:11:46 PM. in epoxidation of alkenes and sity. Her research mainly focuses vegetable oils. on heterogeneous catalysis of vegetable oils and its derivatives. Pingbo Zhang was born in Laiz- Yan Leng was born in 1983 in hou City, Shandong Province of Zhengjiang City, Jiangsu Prov- China. From the School of ince of China. From the School Chemical Engineering and of Chemical and Material Engi- Technology, Tianjin University, neering, Jiangnan University, she received Bachelor's degree in she received her Bachelor's 2004, Master's degree in 2007 degree in 2006 and PhD in 2011. and Doctor's degree in 2009. Aerwards, she joined the Jian- Aerwards, she joined School of gnan University, as a lecturer. Chemical and Material Engi- Her present research interests neering, Jiangnan University, as focus on green catalysis and Associate Professor. Her present sustainable processes by research interests focus on green exploring new catalytic mate- synthesis and catalytic rials composed of ionic liquids, transition metal compounds, het- conversion. eropolyacids, and porous materials. 38120 | RSC Adv.,2019,9, 38119–38136 This journal is © The Royal Society of Chemistry 2019 View Article Online Review RSC Advances studied due to their good catalytic activity and ready avail- starting materials to produce polyols and prepolymers in ability.18 Vegetable oils including edible, non-edible, and waste surface coating formulations and to synthesize polyurethane cooking oils can be transformed into valuable epoxides by the foams.66,67 Epoxidized vegetable oils are intermediates for the conventional homogeneous system (current industrial process), production of isocyanate and non-isocyanate polyurethane. The in which peracids such as performic acid, peracetic acid, and former can be prepared from the ring opening product of EVOs perpropanoic acid are chosen as oxygen carriers in the presence and harmful isocyanate. The pathway for non-isocyanate poly- of H2O2 and inorganic acid catalysts (H2SO4,H3PO4, and urethane consists of a series of esterication, epoxidation,