Combined Process of Hydrocracking and Hydrofining of Coal Tar
Menglong Niu, Zhaoyang Song, Liuyi Pan, Yongli Yan, Ning Liu, Dong Li, Wenhong Li
Abstract
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.