Kinetika Nitrasi Metil Risinoleat, Karakterisasi Dan Uji Produk Sebagai Zat Aditif Peningkat Indeks Setana

Nitration of methyl ricinoleate using the mixture of nitric acid and acetic anhydride has carried out. Methyl ricinoleate nitration was done by varying concentration of methyl ricinoleate and reaction temperature in order to determine the reaction rate (r), order of reaction (n), the reaction rate constant (k), activation energy (Ea), Arhenius frequency factor (f) and the optimum reaction time. The product of the nitration of methyl ricinoleate was then characterized to determine the value of density, viscosity, refractive index, iodine number, solubility in diesel and molecular structure of methyl ricinoleate nitration results using instrument of Fourier Transform Infra Red (FTIR) spectrophotometer and Gas Cromatography-Mass Spectrometer (GC-MS). The characterization of diesel oil after the addition of additive was conducted by determination of specific gravity, viscosity, pour point, flash point, Conradson Carbon Residue (CCR), heat of combustion, and Calculated Cetane Index (CCI) determination. The results showed that the nitration of methyl ricinoleate (0.018 mole) using reagent the mixture nitric acid (0.027 mole) and acetic anhydride (0.027 mole) at a temperature of 29 °C for 90 minutes, producing methyl ricinoleate nitrate of 38%. The nitration rate of methyl ricinoleate with initial methyl ricinoleate concentration of 0.375, 0.319 and 0.261 M was 3.73 x 10-5, 3.00 x 10-5 and 2.69 x 10-5 M sec-1 respectively. The nitration was performed with the excess concentration nitric acid was pseudo first order reaction, with rate constant at 29 oC was 8.67 x 10-5 sec-1. The activation energy (Ea) and frequency factor (f) were 49.77 kJ/mol and 5.51 x 104 sec-1 respectively. The products (sample A) has a density of 0.9678 (g/mL), viscosity 32.43 (cPs), refractive index 1.4604, iodine number 25.8 and completely miscible with diesel fuel. Addition of 0.5% (v/v) the additive (sample A), did not cause the diesel fuel out from diesel fuel specifications and able to increases cetane index of 51 to 54. Therefore, the products of the nitration of methyl ricinoleate can be used as additives for improving of cetane number