Combined Process of Hydrocracking and Hydrofining of Coal Tar

For coal tar hydrotreating technology, the combination of hydrofining and hydrocracking is a valuable research topic. Therefore, this paper will discuss this topic by comparing three different hydrogenation processes, which include hydrofining (process A); catalyst gradation of hydrofining and hydrocracking (process B); and hydrocracking of diesel fraction produced by hydrofining (process C). The research methods are mainly divided into three parts: product composition analysis, product properties analysis, and reaction kinetics analysis. The study reached the following conclusions: First, the combination of hydrofining and hydrocracking can get better quality gasoline and diesel oil. Second, process C has many advantages over process B and process A. The carbon number and hydrogen number of process C products are more concentrated. In process C, alkaline nitrogen is separated from coal tar in the form of ammonia with water or gas, so process C can effectively improve the service life of hydrocracking catalyst. Third, compared with the two catalysts graded and packed in the reactor, the two-stage hydrogenation method is more convenient in adjusting the ratio of gasoline to diesel oil. Finally, process C is recommended to complete the hydrogenation of coal tar through the analysis of the product composition, reaction path, and reaction kinetics.