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Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates
Thesis (MEng)--Stellenbosch University, 2023.
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Stellenbosch : Stellenbosch University
2023
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| access_status_str | Open Access |
| author | Lourens, Corné |
| author2 | Goosen, Neill Jurgens |
| author_browse | Goosen, Neill Jurgens Lourens, Corné |
| author_facet | Goosen, Neill Jurgens Lourens, Corné |
| author_sort | Lourens, Corné |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2023. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/129068 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA en_ZA |
| last_indexed | 2026-06-10T12:41:37.777Z |
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| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2023 |
| publishDateRange | 2023 |
| publishDateSort | 2023 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
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| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/129068 Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates Lourens, Corné Goosen, Neill Jurgens Tadie, Margreth Stellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering. Ether Unsaturated fatty acids Surface active agents Metathesis (Chemistry) Thesis (MEng)--Stellenbosch University, 2023. ENGLISH ABSTRACT: Olefin metathesis is a powerful reaction, particularly relevant in the petrochemical field, which offers new industrial pathways for producing key chemicals. Lately, there has been a growing demand for production of value-added surfactants and chemical intermediates from renewable sources, as part of efforts to move away from fossil-based feedstocks and foster a more sustainable chemical industry. Natural oils, fats and their derivatives hold promise as renewable sources for future developments in the chemical sector. While metathesis of pure functionalised and non-functionalised olefins has been extensively studied, the literature on metathesis of mixtures of functionalised olefins is limited. This study focuses on self-metathesis (SM) of a mixture of unsaturated fatty acid esters (UFAEs) derived from sunflower oil as an alternative pathway for producing value-added surfactants and chemical intermediates. Metathesis of an unrefined mixture of UFAEs was compared to metathesis of a higher purity feedstock (mostly containing one UFAE) to determine differences in product distributions and metathesis performance for the two feedstocks. Within the scope of this project, it was not possible to produce a fatty acid ethyl ester mixture from waste cooking oil due to the complex nature of waste cooking oil, and it should be pretreated properly for producing fatty acid ethyl esters from waste cooking oil. The focus shifted towards a higher purity ethyl oleate and a sunflower-based feedstock from fresh sunflower oil. A higher purity ethyl oleate (HPEO) was prepared from oleic acid through acid catalysed esterification (98.7% yield) and a sunflower-based (SB) feedstock containing a mixture of ethyl esters was obtained through base catalysed transesterification of sunflower oil (82.1% yield). Using ethanol instead of methanol for base catalysed transesterification, added complexity to the process due to ethanol’s lower reactivity, leading to soap formation during the reaction; 3A molecular sieves were effective in resolving this issue. The product distribution for metathesis of these two feedstocks showed that a mixture of ethyl esters (ethyl 9-pentadeceneoate, ethyl oleate, ethyl linoleate, ethyl 9,12-henicosadienoate, ethyl 6,9,12-henicosatrienoate), alkenes (6-dodecene, 6-pentadecene, 6,9-pentadecadiene, 9-octadecene, 6,9-octadecadiene, 6,9,12-octadecatriene) and diesters (diethyl 9-octadecenedioate, diethyl henicosa9,12-diendioate, diethyl tetracosa-9,12,15-triendioate) were to be expected on a theoretical basis. Mass spectra were unavailable because most of the resulting metathesis compounds were not commercially available. However, standards were produced for two main high value metathesis target compounds (9-octadecene and diethyl 9-octadecenedioate) and eight of the twelve expected metathesis products (as mentioned above) were identified using a combination of GC-MS and NMR. Metathesis of these two feedstocks, using Grubbs 2nd generation catalyst, was conducted in sealed tubes while the effect of temperature (20-100 °C), time and catalyst loading (0-0.4 mol%) on the metathesis efficiency was investigated. For the HPEO feedstock, peak performance (with regards to UFAE conversion) was observed at 50 °C at a catalyst loading of 0.2 mol% (67.4% UFAE conversion, turnover Stellenbosch University https://scholar.sun.ac.za iii number (TON) of 337 and primary metathesis product (PMP) yield of 47.7%). In comparison, for the SB feedstock peak performance (with regards to UFAE conversion) was observed at 50 °C and a catalyst loading of 0.4 mol% (87.8% UFAE conversion, TON of 219 and PMP yield of 11.6%). Overall, metathesis of SB feedstock required higher catalyst loadings, possibly due to the feedstock containing impurities (soaps and hydroperoxides) deactivating the catalyst. Organic solvent nanofiltration (OSN) using PuraMem® 280 membrane, was employed to remove the catalyst from reaction mixtures effectively to low levels (1.2-4.5 ppm). Additionally, introducing the 1 st permeate fractions to a 2 nd nanofiltration step, using the same membrane and operating conditions, allowed for partial product fractionation. The mass fraction ratio of diethyl 9-octadecenedioate to 9-octadecene in the 2 nd permeate stream was increased and the ratio was decreased in the 2 nd retentate stream (from 1.18 in reaction mixture from HPEO feed to 1.95 in 1st permeate to 5.87 in 2nd permeate and from 8.45 in the reaction mixture from the SB feed to 13.52 in the 1st permeate to 25.9 in the 2nd permeate). However, complete product fractionation was hindered by compound-membrane interactions and the proximity of molecular weights of the reaction products. Foaming tests of the HPEO feed, SB feed, 1st and 2nd permeate fractions for HPEO reaction mixture and 1 st and 2nd permeate fractions for the SB reaction mixture, showed that the foaming capacity of these mixtures were not comparable to that of Flotanol (industrial frother). The effectiveness of these mixtures as surfactants could not be determined due to critical micelle concentrations (CMC) lacking. The CMCs were lacking because of low water solubility of these mixtures, therefore reaching their solubility limits before the CMC is achieved. Although the CMC values were not measured, the efficiency of the feedstocks and the reaction mixtures were compared by considering the PC20 values. Flotanol had a PC20 of -3.89, HPEO feed -3.92, SB feed -0.95. Furthermore, the PC20 of the HPEO feed and the SB feed increased from -3.92 and -0.95 to -3.62 and -0.42 upon metathesis and consecutive filtration steps (2nd permeate), clearly showing that metathesis upgraded the surfactant potential of the feedstocks since a higher PC20 represents a more efficient surfactant. This study showed that metathesis of ethyl esters derived from sunflower oil, represents a promising pathway for producing a mixture of products (C12-C18 alkenes, C16-C21 ethyl esters and C18-C24 diethyl diesters) with surfactant properties. Further product fractionation could be useful in separating the surface-active compounds from the non-surface-active compounds, of which the latter could find application as chemical intermediates in the chemical synthesis industry. Therefore, this pathway not only facilitates the production of value-added surfactants but also other important chemical intermediates, contributing to a more sustainable and diverse chemical industry. AFRIKAANSE OPSOMMING: Olefin-metatese is 'n kragtige reaksie, veral relevant in die petrochemiese veld, wat nuwe industriële weë bied vir die vervaardiging van sleutel-chemikalieë. Die afgelope tyd was daar 'n groeiende vraag na die produksie van waarde toegevoegde oppervlak-aktiewe middels en chemiese intermediêre uit hernubare bronne, as deel van pogings om weg te beweeg van fossiel-gebaseerde voerstowwe en 'n meer volhoubare chemiese industrie te bevorder. Natuurlike olies, vette en hul afgeleides hou belofte in as hernubare bronne vir toekomstige ontwikkelings in die chemiese sektor. Terwyl metatese van suiwer gefunksioneerde en nie-gefunksioneerde olefiene omvattend bestudeer is, is die literatuur oor metatese van mengsels van gefunksioneerde olefiene beperk. Hierdie studie fokus op self-metatese (SM) van 'n mengsel van onversadigde vetsuur esters (OVEs) afkomstig van sonneblomolie as 'n alternatiewe weg vir die vervaardiging van waarde toegevoegde oppervlak-aktiewe middels en chemiese intermediêre. Metatese van 'n ongeraffineerde mengsel van OVEs is vergelyk met metatese van 'n suiwerder voerstof (wat meestal een OVE bevat) om verskille in produk verspreidings en metatese prestasie tussen die twee voerstowwe te bepaal. Binne die omvang van hierdie projek was dit nie moontlik om 'n vetsuur-etiel ester mengsel vanuit afval kookolie te produseer nie weens die komplekse aard van afval kookolie, en die olie moet dus eers behoorlik behandel word vir die vervaardiging van vetsuur-etiel esters vanuit afvalkookolie. Die fokus van die projek het dus verskuif na a hoër suiwerheid etiel oleaat and ‘n sonneblom-gebaseerde voerstof. 'n Hoërsuiwerheid etiel oleaat (HSEO) is berei uit oliesuur deur suur gekataliseerde esterifikasie (98.7% opbrengs) en 'n sonneblom-gebaseerde voerstof (SB) wat 'n mengsel van etiel esters bevat, is verkry deur middel van basis gekataliseerde transesterifikasie van sonneblomolie (82.1% opbrengs). Die gebruik van etanol in plaas van metanol vir basis gekataliseerde transesterifikasie, het kompleksiteit by die proses gevoeg as gevolg van etanol se laer reaktiwiteit, wat gelei het tot seepvorming tydens transesterifikasie; 3A molekulêre siwwe was effektief om hierdie probleem op te los. Die produk verspreiding vir metatese van hierdie twee voerstowwe het getoon dat 'n mengsel van etiel esters (etiel 9-pentadekenoaat, etiel oleaat, etiel linoleaat, etiel 9,12-henikosadienoaat, etiel 6,9,12- henikosatrienoaat), alkene (6-dodekeen, 6-pentadekeen, 6,9-pentadekadieen, 9-oktadekeen, 6,9-oktadekadieen, 6,9,12-oktadekatrieen) en diesters (di-etiel 9-octadekenedioaat, di-etiel henikosa9,12-dieendioaat, di-etiel tetrakosa-9,12,15-trieendioaat) te wagte was op ʼn teoretiese basis. Die meeste van die gevolglike verbindings was nie kommersieel beskikbaar nie, en massaspektra was nie beskikbaar vir identifikasie nie. Standaarde is egter suksesvol vervaardig vir twee hoofhoëwaardemetatese-teikenverbindings (9-oktadekeen en di-etiel 9-oktadekenedioaat) en agt van die twaalf verwagte metatese produkte is geïdentifiseer met 'n kombinasie van GC-MS en NMR. Stellenbosch University https://scholar.sun.ac.za v Metatese van hierdie twee voerstowwe, met behulp van Grubbs 2de generasie katalisator, is in verseëlde buise uitgevoer, terwyl die effek van temperatuur (20-100 °C), tyd en katalisator lading (0-0.4 mol%) op die metatese-doeltreffendheid ondersoek is. Vir die HSEO voerstof, piekprestasie (met betrekking tot OVEs-omskakeling) is waargeneem by 50 °C teen 'n katalisatorlading van 0.2 mol% (67.4% OVE-omskakeling, TON van 337 en PMP-opbrengs van 47.7%). Ter vergelyking vir die SBvoerstof, piekprestasie (met betrekking tot OVE-omskakeling) is waargeneem by 50 °C en 'n katalisator lading van 0.4 mol% (87.8% OVE-omskakeling, TON van 219 en PMP-opbrengs van 11.6%). Hoër katalisator ladings was benodig vir metatese van SB-voerstof, asgevolg van katalisator deaktivering. Organiese oplosmiddel-nanofiltrasie (OON) met behulp van PuraMem® 280-membraan, is gebruik om die katalisator van die reaksiemengsels effektief te verwyder tot lae vlakke (1.2-4.5 ppm). Daarbenewens het die bekendstelling van die 1ste deurdringende breuke tot 'n tweede nanofiltrasiestap, met dieselfde membraan en toestande, gedeeltelike produk fraksie moontlik gemaak. Die massa fraksie verhouding van di-etiel 9-octadekenedioaat tot 9-oktadekeen in die 2de permeaat stroom is verhoog en die verhouding is verlaag in die 2de retentaat stroom (van 1.18 in reaksiemengsel van HSEO voerstof tot 1.95 in 1ste permeaat tot 5.87 in 2de permeaat en van 8.45 in die reaksiemengsel van die SB voerstof tot 13.52 in die 1ste permeaat tot 25.9 in die 2de permeaat). Volledige produk fraksionering is egter belemmer deur ‘n kombinasie van verbinding-membraan interaksies en die nabyheid van molekulêre massas van die reaksie produkte. Skuimtoetse van die HSEO voerstof, SB voerstof, 1ste en 2de permeaat fraksies vir HSEOreaksiemengsel en 1ste en 2de permeaat fraksies vir die SB-reaksiemengsel, het getoon dat die skuimvermoë van hierdie mengsels nie vergelykbaar is met dié van Flotanol (industriële skuim) nie. Die doeltreffendheid van hierdie mengsels as oppervlak-aktiewe middels kon nie bepaal word nie as gevolg van kritieke micelle konsentrasies (KMK) wat ontbreek as gevolg van lae wateroplosbaarheid van hierdie mengsels, en dus is hul oplosbaarheidsgrense bereik voordat die KMK bereik word. Alhoewel die KMK-waardes ontbreek het, is die doeltreffendheid van die voerstowwe en die reaksiemengsels vergelyk deur die PC20-waardes in ag te neem. Flotanol het 'n PC20 van -3.89, HSEO voerstof -3.92, SB voerstof -0.95. Verder het die PC20 van die HSEO-voerstof en die SB-voerstof toegeneem van -3.92 en -0.95 tot -3.62 en -0.42 met metatese en opeenvolgende filtrasiestappe (2de permeaat fraksie), wat duidelik toon dat metatese die oppervlak-aktiewe potensiaal van die voerstowwe opgegradeer het, aangesien 'n hoër PC20 'n doeltreffender oppervlak-aktiewe middel verteenwoordig. Hierdie studie het getoon dat metatese van etiel esters afkomstig van sonneblomolie 'n belowende weg verteenwoordig vir die vervaardiging van 'n mengsel van produkte (C12-C18 alkene, C16-C21 etiel esters en C18-C24 di-etiel diesters) met oppervlak-aktiewe eienskappe. Verdere produk fraksionering kan nuttig wees om die oppervlak-aktiewe verbindings van die nie-oppervlak-aktiewe verbindings te skei, waarvan die laasgenoemde toepassing as chemiese intermediêre in die chemiese sintetiese bedryf kan vind. Daarom, vergemaklik hierdie pad nie net die produksie van waarde toegevoegde oppervlakaktiewe middels nie, maar ook ander belangrike chemiese intermediêre, wat bydra tot 'n meer volhoubare en’n diverse chemiese industrie. Masters 2023-11-29T08:12:24Z 2024-01-08T21:14:31Z 2023-11-29T08:12:24Z 2024-01-08T21:14:31Z 2023-12 Thesis https://scholar.sun.ac.za/handle/10019.1/129068 en_ZA en_ZA Stellenbosch University xii, 176 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Ether Unsaturated fatty acids Surface active agents Metathesis (Chemistry) Lourens, Corné Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title | Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title_full | Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title_fullStr | Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title_full_unstemmed | Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title_short | Metathesis of unsaturated fatty acid ethyl esters for production of value-added surfactants and chemical intermediates |
| title_sort | metathesis of unsaturated fatty acid ethyl esters for production of value added surfactants and chemical intermediates |
| topic | Ether Unsaturated fatty acids Surface active agents Metathesis (Chemistry) |
| url | https://scholar.sun.ac.za/handle/10019.1/129068 |
| work_keys_str_mv | AT lourenscorne metathesisofunsaturatedfattyacidethylestersforproductionofvalueaddedsurfactantsandchemicalintermediates |