KINETICS OF SULFUR REMOVAL FROM A LIQUID COAL RESIDUE IN THERMAL, HYDROTHERMAL, AND HYDROCATALYTIC CRACKING

An asphaltenic residue from deasphalting a synthetic crude obtained by direct liquefaction of a subbituminous Spanish coal was submitted to several upgrading routes. In this paper, the kinetics of sulfur-remova l reactions in thermal, hydrothermal, and hydrocatalytic cracking are reported. The sulfur-removal reactions fit a 2.7 kinetic order for the thermal process, a 3.8 kinetic order for the hydrothermal process, an d a 4.7 kinetic order for the hydrocatalytic process, the activation e nergy being lowest in the hydrocatalytic process. The activation energ y for the thermal processes is higher in the presence of hydrogen. The percentages of sulfur removal range from 3.6 to 56.6 wt % in thermal cracking, from 15.3 to 61.5 wt % in hydrothermal cracking, and from 19 .1 to 55.0 wt % in hydrocatalytic cracking. The percentages of sulfur removal at low reaction times for the three processes increase in the order thermal < hydrothermal < hydrocatalytic.