Effects of mechanical activation atmosphere on the co-liquefaction of Xigou coal and petroleum vacuum residue

Abstract

The effects of mechanical activation (MA) atmosphere on the co-liquefaction of Xigou coal and Karamay petroleum vacuum residues were investigated. MA induces a smaller particle size of coal powders, which are more easily dissolved in wash oil during co-liquefaction. FT-IR and 13C NMR data of coal samples show that MA can partially break alkyl side chains. Especially, it is easier for MA under hydrogen and air atmosphere to shorten or break alkyl side chains and bridged bonds compared to vacuum and nitrogen atmosphere. MA enhances pyrolysis reaction activity of coal samples through decreasing the apparent activation energy, which is conductive for co-liquefaction. For MA with hydrogen atmosphere, the highest conversion rate and oil yield of co-liquefaction are obtained, which are 98.2% and 84.4%, respectively, followed by air atmosphere. More distillate oil and heavy oil are produced from co-liquefaction with MA under hydrogen atmosphere, but fewer gaseous products. There are 9.7% petrol generated from co-liquefaction with MA under air atmosphere, which are higher than that from other atmospheres. MA partially destroys the physicochemical structure of coal and increases the concentration of free radicals because of the energy generated by collision and friction, thereby enhancing the reactivity in co-liquefaction.