Mathematical models for kinetics of batchwise hydrogenation of shale oil

Hydrogenation of shale oil in a batch autoclave is described by a second order kinetic equation depending on the hydrogen current concentration (H) and on the current value of a total characteristic of the oil (xi), both approaching to their equilibrium levels (H∞, xi∞). Algorithms are proposed to estimate the values of hydrogenation rate coefficient (k) and H∞ from the plot of decrease in hydrogen concentration in time versus H at isothermal conditions. A new concept “specific change of the characteristic” (βi = dxi / dH) is introduced to handle various xi (oil yield, viscosity, density, iodine number, and yield of the fraction 200–275 °C).The equilibrium constants (Ki) and βi for the characteristics are estimated on the basis of experimental results. The temperature-dependencies for k, Ki and βi are determined. A scheme is proposed to predict current values of H and xi for different H0, Tmax and oil mass under isothermal and non-isothermal conditions.The model deduced and the coefficients and constants found can be applied for quantitative evaluation of catalysts and initial oils for hydrogenation.