Selective adsorption of organic sulfur in coal extract by using metal-loaded carbon

The objective of this study was to develop an efficient cleaning process for hydrocarbon resources. We investigated the removal of organic sulfur from coal extract by using metal-loaded carbons. Tetralin and tetralin/phenol mixture were used for thermal extraction of Illinois No. 6 coal at 375 °C with a holding time of 1 h, and we examined the effects of temperature on product yield and sulfur-removal behavior using metal-loaded carbons. A decrease in the n-hexane insoluble fraction was observed at a temperature range from 200 °C to 250 °C in the extracts of tetralin and tetralin/phenol mixture. The organic sulfur content in the n-hexane insoluble fraction drastically decreased with increasing temperature. The organic sulfur in the n-hexane insoluble fraction was reduced above 200 °C, while the sulfur content reached 30–35% at 375 °C for both tetralin and tetralin/phenol mixture extracts. We investigated the effect of holding time on the extent of the coal extract desulfurization using Ni-loaded carbon. The sulfur content in the coal extract decreased as the holding time increased. The rate of coal extract desulfurization using tetralin/phenol was slower than that obtained using tetralin. The coal extract obtained using the tetralin/phenol mixture contained a heavier polar fraction, which may have impeded the adsorption. All organic sulfur in the coal extract could be successfully removed Ni-loaded carbon at a treatment temperature of 350 °C and a holding time of 8 h. No appreciable changes were observed in the content of carbon, hydrogen, or nitrogen at any temperature or holding time in the ultimate analysis of the n-hexane insoluble fraction treated with Ni-loaded carbon. The results demonstrated that Ni-loaded carbon was much effective in removing organic sulfurs from the coal extract.