Pengeluaran biodiesel telah membangun dengan pesat di Malaysia dan ia menjana lebihan gliserol mentah sebagai produk utama bersama. Berdasarkan keadaan semasa, penukaran gliserol kepada bahan kimia nilai tambah yang lebih tinggi seperti asid laktik telah menarik ramai penyelidik untuk memastikan kemampanan ekonomi industri biodiesel. Dalam kajian ini, CaO disokong pada alumina, γ-Al2O3 telah disintesis dengan berbeza muatan CaO (20-50 % berat) dan pengkalsinan terakhir pada suhu optimum iaitu 700 ° C. Pemangkin yang disintesis telah dicirikan melalui analisis permukaan, SEM, TEM, XRD, EDX, FTIR, TGA dan N2 penjerapan sesuhu. Ciri-ciri pemangkin dihubungkaitkan dengan aktiviti mangkin dalam eterifikasi gliserol kepada asid laktik dan prestasi yang ditunjuk berdasarkan penukaran gliserol dan hasil asid laktik. Hasil yang tinggi asid laktik telah dikenal pasti dengan menggunakan pemangkin 30CaO/γ-Al2O3 yang telah disediakan dengan menggunakan 30% berat muatan CaO memuatkan dan dikalsinasikan pada suhu 700 ° C dalam pengeluaran asid laktik daripada gliserol. Kesan keadaan tindak balas seperti muatan pemangkin (5-20 % berat), suhu tindak balas (270-330 °C), masa tindak balas (0.5 - 4 jam) juga dijelaskan dan dihubungkaitkan dengan ciri-ciri mangkin. Selain itu, keadaan tindak balas terbaik diperolehi pada muatan pemangkin 10% berat, suhu tindak balas 290 ° C dan masa tindak balas 2 jam di bawah keadaan, 95% daripada penukaran gliserol dan 49% hasil asid laktik telah dicapai. Dari segi penggunaan semula, pemangkin ini adalah boleh digunakan semula sehingga 3 kali dalam tindak balas dengan penurunan dari 95% kepada 73% dalam penukaran gliserol, manakala penurunan dalam hasil asid laktik dari 47% kepada 27% dalam aktiviti pemangkin. Kajian kinetik pembentukan asid laktik berjaya dilaksanakan dan didapati menepati model kinetic tertib pertama terhadap glycerol dengan tenaga pengaktifan sebanyak 61.730 kJ/mol. Sebagai kesimpulan, 30CaO/γ-Al2O3 merupakan pemangkin yang menunjukkan aktiviti yang baik dan ia merupakan pemangkin aktif yang sesuai untuk digunakan dalam tindak balas yang melibatkan gliserol.
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The biodiesel production has been developing rapidly in Malaysia and it generates a surplus of crude glycerol as the primary co-product. Based on the current situation, the conversion of glycerol to higher value-added chemicals like lactic acid has attracted many researchers to ensure the economic sustainability of the biodiesel industry. In the present work, CaO supported on alumina, γ-Al2O3 catalyst was synthesized with different CaO loadings (20-50 wt. %) and the final calcination at optimum temperature was 700 °C. The synthesized catalyst were then characterized by means of surface analysis, SEM, TEM, XRD, EDX, FTIR, TGA and N2 adsorption-desorption isotherm. The characteristics of the catalysts were correlated with the catalytic activity in glycerol etherification and the performance demonstrated based on the glycerol conversion and lactic acid yield. It was found that high yield of lactic acid was identified by using 30CaO/γ-Al2O3 catalyst which was prepared using 30 wt.% of CaO loading and calcined at 700 °C in the production of lactic acid from glycerol. Effects of reaction condition such as catalyst loadings (5-20 wt. %), reaction temperature (270-330 °C), reaction time (0.5-4 h) were also explained and correlated with the characteristics of the catalysts. On top of that, the best reaction conditions were obtained at 10 wt. % of catalyst loading, a reaction temperature of 290 °C and a reaction time of 2 h. Under these conditions, using 30CaO/γ-Al2O3 catalyst, 95 % of glycerol conversion and 49 % of lactic acid yield were obtained. In terms of reusability, this catalyst was reusable for up to 3 times in this reaction with decrease from 95% to 73% for glycerol conversion, while decrease from 47% to 27% in lactic acid yield in the catalytic activity. The kinetic study of lactic acid formation was successfully conducted with a first order kinetic model and the activation energy of reaction of 61.730 kJ/mol was determined. As a conclusion, 30CaO/γ-Al2O3 catalyst showed good activity and it is an active catalyst that is suitable to be used in the reaction involving glycerol.
Selective conversion of glycerol to lactic acid by CaO γ-Al2O3 supported catalyst / Kartina Mbong