In this paper, we report on our effort to design a novel lithium salt derived from bis(trifluoroborane)benzimidazolide by using density functional theory (DFT) calculations. The effects of different substituents are investigated with respect to ion pair dissociation energies and intrinsic anion oxidation potential of the molecules. Based on our calculations, we have found that ion pair dissociation energies and intrinsic anion oxidation potentials of the anions are mainly affected by the position and the type of substituents introduced into the parent structure. Compared to -CH3, substitution at the C2 position of the parent bis(trifluoroborane)benzimidazole (BTB(-)) by -CF3 results in an increase in anion oxidation stability. However, we observed a negligible change in the intrinsic anion oxidation potential as the length of the fluoroalkyl group increased to -C2F5. The most promising anions are generated by considering double-substitution at C2 and C5 positions. Among the possible anions, bis(trifluoroborane)-5-nitro-2-(trifluoromethyl) benzimidazolide (BTNTB(-)), with the calculated intrinsic anion oxidation potential of 5.50 V vs. Li(+)/Li, can be considered as a potential candidate for high voltage Li-ion batteries.
Abstrak- Bioethanol merupakan salah satu sumber energi alternatif yang sangat berpeluang untuk dikembangkan di Indonesia. Selain sebagai bahan baku alam yang dapat diperbaharui dan bersifat ramah lingkungan, bioethanol juga dapat dimanfaatkan sebagai bahan bakar substitutif maupun aditif pada bahan bakar fosil. Namun kenyataannya bioethanol hasil fermentasi hanya mempunyai kadar ethanol sebesar 10-15%, sedangkan untuk dapat digunakan sebagai bahan bakar atau bahan substitusi bioethanol harus mempunyai kemurnian mencapai 99,5%. Dalam proses pemurniannya, air yang terdapat pada bioethanol akan membuat campuran azeotrop sehingga sulit dipisahkan dengan proses distilasi biasa. Salah satu metode pemisahan untuk memisahkan campuran azeotrop adalah dengan menggunakan metode distilasi azeotrop. Pada distilas ini akan ditambahkan entrainer yaitu zat yang berperan mengubah volatilitas relatif komponen kunci. Untuk menaikan kadar bioethanol dan mengetahui pengaruh entrainer pada distilasi azeotrop digunakan dua jenis entrainer yaitu benzene dan n-heptane. Dari hasil penelitian didapatkan bahwa benzene yang mempunyai gugus aromatik dapat menaikan kadar ethanol lebih baik dibadingkan dengan n-heptane dan cyclohexane. Keywords: bioethanol, distilasi azeotrop, entrainer, benzene, n-heptane
The main goal of this work is optimize low temperature shift converter (LTS) of Carbon Monoxide (CO) in an Industrial Ammonia Plant considering life time of the catalyst in that converter. Shift converter is a reactor to convert CO into carbon dioxide. CO in ammonia plant comes from steam reforming process that convert natural gas into hydrogen gas. This process will also produce CO gas, where CO gas is toxic to the catalyst in ammonia syntesis reactor and also able to oxidize Fe in ammonia synthesis that is the reason why CO is one of component that can interfere the ammonia gas manufacturing process. To prevent this, the CO gas purification process needs to be done, one of the method is using shift converter process. From the optimization of several operating conditions in low temperature shift converter, a relatively strong correlation is found between flow rate feed and average temperature bed catalyst with the lifetime of the catalyst. The optimization result show that the optimum flow rate feed in LTS is 2754.49 m3/day and average temperature bed catalyst is 224°C. Operating at the proposed optimal condition increases life time of the catalyst about 8.02% per year.
Salah satu sumber energi alternatif yang potensial dikembangkan di Indonesia adalah bioethanol. Serat siwalan adalah limbah organik yang potensial dikembangkan sebagai bahan baku bioethanol. Proses delignifikasi diperlukan sebelum limbah siwalan difermentasi menjadi bioethanol. Pada proses ini, lignin yang terdapat pada serat siwalan akan dipecah untuk mendapatkan selulosa yang dikonversi menjadi gula. Dari hasil penelitian diperoleh bahwa konsentrasi NaOH 1N mampu meningkatkan kadar selulosa hingga 71,37% dibanding dengan konsentrasi NaOH 2N yang hanya mampu menaikkan kadar selulosa sebesar 59,53%. Untuk waktu pemanasan optimal pada proses ini adalah 30 menit pada suhi 100 oCKata kunci: limbah siwalan, delignifikasi, NaOH, bioethanol, lignin, selulosa
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