Sulfated Zirconia Supported on Sba-15 For Selective Glycerol Esterification with Palmitic Acid to Monopalmitin

Mohd Yusoff, Mohd Hizami (2016) Sulfated Zirconia Supported on Sba-15 For Selective Glycerol Esterification with Palmitic Acid to Monopalmitin. PhD thesis, Universiti Sains Malaysia.

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    Abstract

    Peningkatan pesat dalam pengeluaran biodiesel di Malaysia menjana lebihan gliserol mentah sebagai produk utama yang mempunyai aplikasi yang terhad dalam industri tempatan. Berdasarkan keadaan semasa, penukaran gliserol kepada produk bernilai tinggi seperti monogliserida adalah satu alternatif yang menarik. Dalam kajian ini, mangkin meso liang SZSBA-15 telah disintesis dengan muatan zirkonia (5 – 20 % berat) dan suhu pengkalsinan akhir (450 – 650 oC) yang berbeza. Mangkin-mangkin yang disintesis telah dicirikan melalui analisis permukaan, SEM, TEM, XRD, FTIR, EDX, TGA, NH3-TPD dan penentuan keasidan melalui titratan. Ciri-ciri mangkin tersebut kemudiannya dikaitkan dengan aktiviti mangkin dalam pengesteran gliserol dengan asid palmitik dan prestasinya ditunjuk berdasarkan penukaran asid palmitic dan hasil monopalmitin. Kesan keadaan tindak balas seperti masa (1 – 6 jam), kadar aliran N2 (5 – 40 cm3/min), suhu tindak balas (160 – 180 oC), muatan mangkin (1 – 3 % berat), nisbah bilangan mol gliserol/asid palmitik (2:1 – 6:1) juga dijelaskan dan dikaitkan dengan ciri-ciri mangkin. Didapati bahawa mangkin SZSBA-15 yang disediakan menggunakan 10 % berat muatan zirkonia dan dikalsin pada 500 oC (10SZSBA-15(500)) menunjukkan aktiviti yang tinggi dalam penghasilan monopalmitin. Peningkatan masa tindakbalas, kadar aliran N2, suhu tindakbalas dan muatan mangkin telah meningkatkan penukaran asid palmitik. Sebaliknya, perubahan dalam penukaran asid palmitik tidak ketara apabila nisbah bilangan mol melebihi 4:1. Tambahan pula, keadaan tindak balas terbaik telah diperolehi pada masa tindak balas 3 jam, suhu tindak balas 170 oC, muatan mangkin 2 % berat dan nisbah gliserol/asid palmitik 4:1. Di bawah keadaan ini menggunakan mangkin 10SZSBA-15(500), sebanyak 86 % penukaran asid palmitik dan 43 % hasil monopalmitin telah diperolehi. Dari segi kebolehgunaan semula, mangkin ini boleh digunakan semula sehingga empat kali dalam tindak balas ini dengan sedikit penurunan dalam aktiviti pemangkin. Ini disebabkan oleh kehilangan kumpulan sulfur daripada mangkin. Walau bagaimanapun, struktur liang tidak terjejas setelah empat kitaran pemangkin. Pengesteran gliserol dengan asid palmitik didapati menepati model kinetik tertib kedua terhadap gliserol dan asid palmitik dengan tenaga pengaktifan yang rendah sebanyak 38.2 kJ/mol. Sebagai kesimpulan, mangkin 10SZSBA-15(500) yang menunjukkan aktiviti yang baik merupakan mangkin aktif dan sesuai digunakan dalam tindak balas melibatkan molekul-molekul besar. ________________________________________________________________________________________________________________________ The rapid increase of biodiesel production in Malaysia generates an excess of crude glycerol as the primary co-product which has limited application in local industries. Based on the current situation, the conversion of glycerol to higher value products like monoglyceride is an attractive alternative. In the present work, mesoporous SZSBA-15 catalyst has been synthesized with different zirconia loadings (5 - 20 wt. %) and final calcination temperatures (450 – 650 oC). The synthesized catalysts were characterized by means of surface analysis, SEM, TEM, XRD, FTIR, EDX, TGA, NH3-TPD and determination of acidity by titration. The characteristics of the catalyst were then correlated with the catalytic activity in glycerol esterification with palmitic acid and the performance was demonstrated based on the palmitic acid conversion and monopalmitin yield. Effects of reaction conditions such as time (1 – 6 h), N2 flow rate (5 – 40 cm3/min), reaction temperature (160 – 180 oC), catalyst loading (1 – 3 wt. %) and glycerol/palmitic acid molar ratio (2:1 – 6:1) were also elucidated and correlated with the characteristics of the catalysts. It was found that SZSBA-15 catalyst prepared using 10 wt. % of zirconia loading and calcined at 500 oC (10SZSBA-15(500)) demonstrated high activity in the production of monopalmitin. An increase in the reaction time, nitrogen flow rate, reaction temperature and catalyst loading increased the conversion of palmitic acid. On the contrary, changes in the palmitic acid conversion was insignificant when the molar ratio exceeded 4:1. On top of that, the best reaction conditions were obtained at a reaction time of 3 h, a reaction temperature of 170 oC, 2 wt. % of catalyst loading and 4:1 of glycerol/palmitic acid molar ratio. Under these conditions using 10SZSBA-15(500) catalyst, 86 % of palmitic acid conversion and 43 % monopalmitin yield were obtained. In terms of reusability, this catalyst was reusable for up to four times in this reaction with slight decrease in the catalytic activity. This was attributed to the loss of sulfur groups from the catalyst. Nevertheless, the pore structure remained unaffected after four catalytic cycles. The glycerol esterification with palmitic acid was found to follow a second order kinetic model with respect to glycerol and palmitic acid with a low activation energy of 38.2 kJ/mol. As a conclusion, 10SZSBA-15(500) catalyst which exhibited good activity was as an active catalyst and suitable to be used in the reaction involving bulky molecules.

    Item Type: Thesis (PhD)
    Additional Information: full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=2070
    Subjects: T Technology
    T Technology > TP Chemical Technology > TP248.13-248.65 Biotechnology
    Divisions: Kampus Kejuruteraan (Engineering Campus) > Pusat Pengajian Kejuruteraan Kimia (School of Chemical Engineering) > Thesis
    Depositing User: Mr Mohd Jasnizam Mohd Salleh
    Date Deposited: 12 Jun 2018 10:11
    Last Modified: 12 Jun 2018 10:11
    URI: http://eprints.usm.my/id/eprint/40752

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