Yaacob, Muhammad Hazim (2018) Selective Conversion Of Glycerol To Lactic Acid Using Nickel Supported On Calcium Oxide And Magnesium Oxide. Masters thesis, Universiti Sains Malaysia.
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Abstract
Peningkatan pesat dalam pengeluaran biodiesel di seluruh dunia menjana lebihan gliserol mentah sebagai produk utama yang memberi kesan yang buruk kepada harga pasaran gliserol. Untuk mengekalkan industri gliserol, pembangunan kepada produk bernilai tinggi daripada gliserol amat diperlukan. Asid laktik telah mendapat perhatian yang meluas disebabkan kepelbagaian aplikasinya di dalam industri makanan, kosmetik dan farmaseutikal. Dalam penyelidikan ini, gliserol telah ditukarkan kepada asid laktik melalui tindak balas pemangkin bes. Jenis mangkin yang berbeza (MgO, CaO, NiO, NiO/MgO dan NiO/CaO) telah digunakan pada tindak balas ini. Di antara pemangkin ini, NiO/CaO menunjukkan aktiviti yang tinggi dan telah dipilih untuk kajian yang seterusnya. Mangkin NiO/CaO telah disentesis dengan nisbah molar Ni/Ca (0.25, 0.43 dan 0.67) dan suhu pengkalsinan yang berbeza (800, 900 dan 1000°C). Di samping itu, sifat fizikokimia bagi mangkin ini telah dicirikan melalui penjerapan nitrogen, penyahjerapan karbon dioksida berprogramkan suhu (CO2-TPD), mikroskop pengimbas elektron (SEM) dan analisis gravimetri termal (TGA). Kesan keadaan tindak balas seperti masa tindak balas (30–160 minit), suhu tindak balas (280-300°C) dan bebanan mangkin (10-20 % berat) dikaji bagi mengenalpasti keadaan tindak balas yang terbaik untuk dapatkan hasil asid laktik yang tinggi. Didapati bahawa mangkin NiO/CaO menunjukkan aktiviti yang tertinggi dengan nisbah Ni/Ca 0.43 dan dikalsin pada 900°C. Tambahan lagi, didapati mangkin ini sesuai untuk digunakan pada tindak balas ini kerana ia memiliki kadar bes yang tinggi iaitu 11.28 mmol/g. Oleh itu, peningkatan jumlah bes pada mangkin mungkin menggalakkan pertukaran gliserol kepada asid laktik. 93.2% penukaran gliserol dan 41.3% hasil asid laktik telah berjaya diperolehi pada 290°C dalam 1.5 jam dengan bebanan mangkin 15% berat. Selain itu, mangkin ini boleh digunakan semula sehingga dua kali dengan sedikit penurunan dalam penukaran gliserol dari 89.3% ke 78.0%. Ini disebabkan oleh pengurasan kalsium daripada mangkin ke dalam gliserol. Walau bagaimanapun, sebanyak 28.7% hasil asid laktik boleh diperolehi setelah dua kitaran pemangkin. Model kinetik bagi kepekatan gliserol dalam penukaran gliserol dengan menggunakan 0.43NiO/CaO-900 sebagai mangkin telah juga dibangunkan. Model ini mampu untuk menerangkan reaksi sebenar di dalam reaktor pada kadar suhu 280-300°C. Oleh itu, ia kelihatan yang mangkin NiO/CaO mempunyai potensi pemangkin untuk penghasilan asid laktik dari gliserol. _______________________________________________________________________________________________________ The rapid increase of biodiesel production worldwide generates an excess of crude glycerol as the primary co-product which negatively affect the price of glycerol in the market. In order to sustain the glycerol industry, the development of value-added chemicals from glycerol is necessary. Among them, lactic acid has received a considerable attention due to its numerous applications in the food, cosmetic and pharmaceutical industries. In this study, glycerol was upgraded to lactic acid through a base catalyzed reaction. Different types of catalyst (MgO, CaO, NiO, NiO/MgO and NiO/CaO) were used in this reaction. Among these catalysts, NiO/CaO showed high activity and was selected for the following study. NiO/CaO catalysts were synthesized with different molar ratios of Ni/Ca (0.25, 0.43 and 0.67) and calcination temperatures (800, 900 and 1000°C). In addition, the physicochemical properties of these catalysts were characterized by nitrogen adsorption, temperature programmed desorption of carbon dioxide (CO2-TPD), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). Effects of reaction conditions such as reaction time (30-160 min), reaction temperature (280-300°C) and catalyst loading (10-20 wt. %) were also studied to identify the best reaction conditions obtain high lactic acid yield. It was found that NiO/CaO catalyst demonstrated the highest activity at a Ni/Ca ratio of 0.43 and calcined at 900°C. Furthermore, this catalyst was found to be excellent to be used in this reaction as it possessed the high amount basicity of 11.28 mmol/g. Thus, the increase in the total basicity of the catalyst might have favored its glycerol conversion to lactic acid. 93.2% of glycerol was converted to give 41.3% yield of lactic. Besides, this catalyst was reusable up to two cycles with a reduction in glycerol conversion from 89.3% to 78.0%. This could be due to leaching of calcium from the catalyst into glycerol. Nevertheless, high yield of lactic acid up to 28.7% could still be obtained after two catalytic cycles. A kinetic model for the glycerol concentration in glycerol conversion using 0.43NiO/CaO-900 as catalyst is also developed. This model could well describe the actual reaction occurring in the reactor in a temperature range of 280-300°C. Therefore, it appeared that CaO/NiO catalyst is a potential catalyst for lactic acid production from glycerol.
| Item Type: | Thesis (Masters) |
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| Additional Information: | Full text is available at http://irplus.eng.usm.my:8080/ir_plus/institutionalPublicationPublicView.action?institutionalItemId=4721 |
| 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: | 19 Jun 2019 08:18 |
| Last Modified: | 19 Jun 2019 08:18 |
| URI: | http://eprints.usm.my/id/eprint/44670 |
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