Experimental Study of Supercritical Ethanol Deoxygenation of Shengli Lignite

Abstract

In this study, supercritical ethanol process is employed to remove the oxygen-containing functional groups in lignite and the effects of temperature, residence time and ethanol /coal mass ratio on the deoxygenation were systematically investigated. Specifically, the solid and liquid products after supercritical ethanol deoxygenation were characterized by FT-IR and GC/MS. Considering the deoxygenation rate (61.40%) and solid yield (89.62%), the optimal deoxygenation was achieved at 270°C with the residence time of 90 mins and alcohol/coal mass ratio of 5:1. In the liquid products generated at 220°C, the content of aromatic compounds was about 80% while the content of phenols and ester compounds was less than 5%. However, for the liquid products obtained at 270°C, the content of aromatic compounds was decreased by 31.69 % while the volume fraction of O-containing compounds was increased by 2.81 % and the content of phenols and ester compounds was increased to about 35%. During supercritical ethanol process, ether oxygen bonds were cracked. For the O-containing species in the products, phenol and its derivatives were the main components in solid products and esters (mostly ethyl esters) in liquid products.