Study on preparation of high aromatic potential naphtha from pyrolysis heavy oil via hydrocracking

The heavy fraction of Hami pyrolysis tar was firstly hydrocracked in a suspended bed reactor, and the as-prepared light product oil was analyzed. The light oil that retains the basic unit structure characteristics of coal and contains a large number of naphthenes and aromatic compounds as well as high nitrogen content was then used to produce naphtha in a 200 mL fixed bed refining-cracking tandem unit. The effect of different temperatures on the hydrocracking reaction was investigated at reaction pressure of 15 MPa. The results show that the optimum cracking temperature is 390℃, at which the conversion of >180℃ fraction is 53.69%, the hydrogen consumption is 5.13%, and the < 180℃ naphtha yield reaches 56.8%. The main components of naphtha are C_6-9 hydrocarbons with the naphtha of 71.99%, the naphthene of 3.13% aromatics and the aromatic potential of 70.1. The catalytic reforming of cracked naphtha under optimum conditions to produce BTXE was conducted and compared with that with the middle base naphtha of petroleum series as feed. After reforming, the yield of BTXE from cracking naphtha is 55.85%, 25.53% higher than that from petroleum-based naphtha. The advantages and characteristics of coal-based oil are highlighted. It is verified that naphtha from coal pyrolysis heavy oil hydrocracking is a good raw material for preparing BTXE.