Shuit , Siew Hoong (2015) Studies on The Sulfonated Carbon Nanotubes Catalyst and Membrane Reactor for Biodiesel Production. PhD thesis, Universiti Sains Malaysia.
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Abstract
Tumpuan kajian ini ialah penghasilan biodiesel dengan menggunakan sulfonat tiub-nano karbon dinding berlapis (s-MWCNTs) sebagai pemangkin dan reaktor membran jenis pervaporasi sebagai teknologi pertukaran. Pada mulanya, s-MWCNTs disintesis dan diguna untuk menukar sulingan asid lemak sawit (PFAD) kepada biodiesel. Hasilan biodiesel yang dicapai oleh s-MWCNTs yang disediakan melalui rawatan haba dengan asid sulfurik pekat, in-situ pempolimeran asetik anhydride dan asid sulfurik, penguraian haba ammonium sulfat ((NH4)2SO4) dan in-situ pempolimeran poli(natrium4-stirenasulfonat) ialah masing-masing 78.1 %, 85.8 %, 88.0 % dan 93.4 %. Penguraian haba (NH4)2SO4 ialah kaedah yang paling sesuai dalam penyediaan s-MWCNTs kerana ia adalah satu kaedah yang mudah dan bebas asid. Seterusnya, kesan kepekatan larutan (NH4)2SO4 dan tempoh ultrasonikasi MWCNTs dalam larutan (NH4)2SO4 dikaji dan dioptimumkan. Prestasi s-MWCNTs yang terbaik boleh diperolehi dengan ultrasonik campuran MWCNTs tulen dalam 10 % berat larutan (NH4)2SO4 selama 10 minit dan dipanaskan pada suhu 235 °C selama 30 minit. s-MWCNTs yang disediakan melalui cara ini memaparkan kestabilan haba dan penyebaran di dalam metanol yang baik serta mempunyai kawasan permukaan Brunauer-Emmett-Teller (BET) dan diameter liang yang besar. Kemudian, s-MWCNTs yang telah dioptimumkan diguna untuk kajian proses, kajian kinetik, penggunaan dan penjanaan semula pemangkin untuk menunjukkan potensi s-MWCNTs sebagai pemangkin dalam penghasilan biodiesel. Kajian proses termasuk nisbah metanol kepada PFAD (8 – 30), pemuatan pemangkin (1 – 3 % berat), suhu tindak balas (80 – 200 ºC) dan masa bertindak balas (1 – 5 jam). Hasilan biodiesel setinggi 93.5 diperolehi pada nisbah metanol kepada PFAD 20, 3 % berat pemangkin, suhu 170 ºC dan masa bertindak balas selama 2 jam. s-MWCNTs menunjuk aktiviti pemangkinan yang baik dengan hasilan biodiesel melebihi 75 % walaupun selepas penggunaan kelima. Penjanaan s-MWCNTs (setelah 5 kitaran) dengan asid sulfurik berjaya memulih aktiviti pemangkinan s-MWCNTs ke paras asalnya. Model kinetik pseudo-homogen bagi esterifikasi PFAD dengan metanol diterbit berdasarkan keputusan eksperimen. Faktor praeksponen, haba molar dan tenaga pengaktifan untuk tindak balas esterifikasi ialah 1.9 × 102 L mol-1min-1, 84.1 kJ mol-1 and 45.8 kJ mol-1 masing-masing. Seterusnya, poliimeda, kopoli(1,5-naftalena/3,5-asidbenzoik-2,2’-bis(3,4-dikarboksifenil) heksafluoropropanadimeda (6FDA-NDA/DABA) disintesis dan diubah-suai dengan perangkaian silang pasa suhu tinggi untuk dijadikan membran dalam reaktor membran. Dalam masa tindak balas selama 10 jam, membran polyimide 6FDA-NDA/DABA yang dirangkai silang berjaya menyingkirkan 94.8 % air yang dihasilkan dalam tindak balas esterifikasi. Peratus penyingkiran air yang tinggi oleh membran poliimeda ini telah mencetuskan peningkatan sebanyak 17.9 % dalam hasilan biodiesel yang dicapai oleh reaktor membran berbanding dengan reaktor kelompok di bawah keadaan tindak balas yang sama. Membran poliimeda 6FDA-NDA/DABA yang dirangkai silang merupakan membran bersifat hidrofilik yang menunjukkan darjah pengampulan yang boleh diabaikan pada larutan tindak balas, dan kestabilan haba yang tinggi pada suhu serta tekanan tindak balas yang tinggi. ____________________________________________________________________________________________________________________________ This study focused on the synthesis of biodiesel using sulfonated multi-walled carbon nanotubes (s-MWCNTs) as catalyst and pervaporation membrane reactor as the conversion technology. First, s-MWCNTs were synthesized and utilized as catalysts to transform palm fatty acid distillate (PFAD) into biodiesel. The biodiesel yields achieved by the s-MWCNTs prepared via thermal treatment with concentrated sulfuric acid, the in situ polymerization of acetic anhydride and sulfuric acid, the thermal decomposition of ammonium sulfate ((NH4)2SO4) and the in situ polymerization of poly(sodium4-styrenesulfonate) were 78.1 %, 85.8 %, 88.0 % and 93.4 %, respectively. Sulfonation via the thermal decomposition of (NH4)2SO4 was the most suitable method to prepare s-MWCNTs because it is a facile and acid-free method. Next, the effects of the concentration of (NH4)2SO4 solution and the ultrasonication period of MWCNTs in the (NH4)2SO4 solution were studied and optimized. The results showed that the best performance of the s-MWCNTs was obtained by ultrasonicating the purified MWCNTs in a 10 wt% (NH4)2SO4 solution for 10 min and heating at 235 °C for 30 min. s-MWCNTs prepared by this method demonstrated good thermal stability, good dispersibility in methanol and high Brunauer-Emmett-Teller (BET) surface area coupled with a large pore width. Then, the optimized s-MWCNTs were subjected to process parameters study, kinetic study, catalyst reusability and regeneration study to reveal the potential of s-MWCNTs as a catalyst for biodiesel production. The process parameters studied included the methanol-to-PFAD ratio (8 – 30), catalyst loading (1 – 3 wt %), reaction temperature (80 – 200 ºC) and reaction time (1 – 5 h). A high FAME yield of 93.5 % was obtained at a methanol-to-PFAD ratio of 20, catalyst loading of 3 wt %, reaction temperature of 170 ºC and reaction time of 2 h. The s-MWCNTs exhibited good catalytic activity, with a FAME yield higher than 75 % even after 5 repeated runs. The regeneration of the spent s-MWCNTs (after 5 runs) with sulfuric acid was able to restore the catalytic activity to its original level. A pseudo-homogeneous kinetic model for the esterification of PFAD with methanol using s-MWCNTs as a catalyst was then developed based on the experimental results. The pre-exponential factor, molar heat and activation energy for the esterification were found to be 1.9 × 102 L mol-1min-1, 84.1 kJ mol-1 and 45.8 kJ mol-1, respectively. Then, the polyimide, copoly(1,5-naphthalene/3,5-benzoicacid-2,2’-bis(3,4-dicarboxyphenyl) hexafluoropropanedimide (6FDA-NDA/DABA) was synthesized and modified via thermal cross-linking to serve as a membrane in membrane reactor. At 10 h of reaction time, the thermally cross-linked 6FDA-NDA/DABA polyimide membrane was able to remove 94.8 % of the generated water from the reaction mixture. The high removal percentage of water by the polyimide membrane has triggered a 17.9 % increment of FAME yield achieved by pervaporation membrane reactor as compared to the FAME yield achieved by the batch reactor under the same reaction conditions. The thermally cross-linked polyimide membrane was a hydrophilic membrane which demonstrated negligible swelling degree in the reaction mixture and high thermal stability under high reaction temperature and pressure.
| Item Type: | Thesis (PhD) |
|---|---|
| Additional Information: | Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=2120 |
| Subjects: | T Technology T Technology > TP Chemical Technology > TP1-1185 Chemical technology |
| Divisions: | Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Kimia (School of Chemical Engineering) > Thesis |
| Depositing User: | Mr Mohd Jasnizam Mohd Salleh |
| Date Deposited: | 13 Jun 2018 03:19 |
| Last Modified: | 13 Jun 2018 03:19 |
| URI: | http://eprints.usm.my/id/eprint/40782 |
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