Liquid–liquid equilibrium (LLE) data for the ternary system composed of diethyl carbonate (DEC) + 1-propanol + water were measured under atmospheric pressure (101.32 ± 1 kPa) at temperature range of 303.15–333.15 K. The equilibrium data were found to be consistent with the Bachman–Brown method. The data were further correlated with the nonrandom two-liquid (NRTL) and the universal quasi-chemical (UNIQUAC) models, and 0.37% root-mean-square deviation was obtained between the experimental and calculated phase composition. Distribution coefficient and separation factor for this ternary system were calculated from the experimental data.

This study successfully improved the performance of oxidative desulfurization method to reduce sulfur content from residue oil (condensate) with modifications of oxidation and extraction steps which was repeated for several stages. Residue oil used in this study contain 386.2 ppm of initial sulfur content. In oxidation process, H2O2 as oxidizer and acid as catalyst were used within temperature range of 30–60 °C and time interval from 30 to 120 min. In extraction process, various alcohol solvents (methanol, ethanol, and propanol) were used with the temperature of 30 °C in 30 min for every residue oil ratio to solvent (v/v). The best reducing sulfur result achieved was 35.9 ppm or 90.7% desulfurization. This result was achieved after 4 recursively extractions using ethanol as solvent. This study successfully reduced sulfur content in residue oil to meet the international standard (< 50 ppm).

No abstract

In this work, the vapor pressure of binary mixtures of 2-butanol + diethyl carbonate and tert-butanol + diethyl carbonate was measured in the temperature range from 303.15 to 323.15 K. The experimental apparatus used in this work was a simple quasi-static ebulliometer developed in our previous works. The reliability of this apparatus was verified by comparing the measured vapor pressures of 2-butanveol, tert-butanol, and diethyl carbonate with literature data. The comparisons showed that the vapor pressures of pure 2-butanol, tert-butanol, and diethyl carbonate were in good agreement with the literature data with average absolute deviations of 0.6, 0.6, and 0.8%, respectively. The experimental results show that the vapor pressures increased with the alcohol mole fraction for all systems studied. The experimental data were well-correlated with the Wilson, nonrandom two-liquid, and universal quasichemical activity coefficient models, giving an average absolute deviation of no more than 1.9%. The binary vapor−liquid equilibrium data obtained in this work showed a positive deviation from Raoult's law.

Urea adalah pupuk kimia mengandung Nitrogen (N) berkadar tinggi. Unsur Nitrogen merupakan zat hara yang sangat diperlukan tanaman. Bahan baku utama pada proses pembuatan pupuk urea adalah gas alam. Namun ketersediaan gas alam semakin menipis jumlahnya, sehingga perlu dikembangkan teknologi proses yang memungkinkan substitusi bahan baku gas sintesis. Bahan baku yang paling memungkinkan untuk menggantikan gas alam adalah batubara, baik melalui teknologi CBM (Coal Bed Methane) maupun teknologi gasifikasi. Produksi pupuk urea melalui 4 tahapan yaitu pembentukan syngas, pemisahan sulphur dari syngas, pembentukan ammonia, dan pembentukan urea. Perbedaan dari proses yang ada, lebih pada perlakuan awal untuk pembentukan syngas (CO dan H2). Hal ini disesuaikan kondisi bahan baku yang digunakan (batubara, gas alam, dan biomassa).Dari hasil analisa ekonomi tersebut terlihat bahwa IRR sebesar 34,84%, dengan POT pada tahun ketiga menginjak tahun keempat. Selain itu, terlihat bahwa fluktuatif bahan baku tidak memberikan pengaruh yang cukup signifikan terhadap kenaikan atau penurunan nilai IRR pabrik. Sehingga pabrik pupuk urea dari bahan batubara kelas rendah berkapasitas 1.25 Juta ton urea/tahun dan 590000 ton ammonia/tahun ini layak didirikan di Tanjung Enim, Muara Enim, Sumatra Selatan pada tahun 2019.