Kinetic parameter estimation and reactor simulation of full-range low temperature coal tar during hydrodeasphaltenization over Ni–Mo/γ-Al2O3

Abstract

In this study, the whole fraction low temperature coal tar (LTCT) was used as raw material, a series of hydrodeasphaltenization (HDAs) experiments were conducted in an isothermal trickle bed reactor, then the kinetic equation of the reaction was established in gPROMS software and the parameters were estimated. The trickle bed reactor model was established and the effects of operating conditions on HDAs reaction and catalyst effective factors were analyzed. The reactor temperature was varied from 623 to 683 K, the hydrogen pressure from 6 to 12 MPa, keeping constant hydrogen-to-oil volume ratio at 1000:1, liquid hourly space velocity at 0.5 h−1. The results showed that the relative error between the experimental and the simulated results were less than ± 5%, which proved that the model had good applicability; the activation energy was 149.8 kJ mol−1, the pre-exponential factor was 633,832, the reaction order was 1.347, and the order of hydrogen was 2.33. The higher activation energy indicated that the HDAs was difficult to occur compared with the reaction in crude oil. And the high hydrogen order indicated that the pressure had a significant influence on the reaction rate. However, the high temperature and low pressure would reduce the effective factor of the catalyst. The reason may be that the large diffusion limitation and reaction heat of asphaltenes lead to a large difference in reaction rates between the catalyst surface and the tunnel of pores under high temperature. This study could contribute to a more in-depth understanding of the features and rules of LTCT HDAs, and also provide a useful model for reactor design, operation and control.