Study On Hydrodenitrogenation Catalyst Of Full-range Low-Temperature Coal Tar

With the roiling of the international crude oil market, crude oil prices remain at a high level. The dependency of China’s fast-growing economy on crude oil imports has also become more serious. Thus, in recent years, the development of non-oil processing route for preparing alternative fuel oil has been concerned by researchers. In our country, coal tar can’t convert to high value-added products cleanly and efficiently, and the utilization of coal tar is very low. So taking advantage of the full-range coal tar hydrotreating technology for cleaning fuel oil has great market potential and high strategic significance.Today, much coal tar hydrogenation catalyst is transplanted from heavy crude oil hydrogenation process. But there are many differences between heavy oil and coal tar, especially the characteristics of high nitrogen and low sulfur of coal tar cause the existing catalyst system can not achieve the ideal hydrogenation effect. The nitrogen content of the product after hydrotreating can not meet the requirements of the cracking catalyst. Therefore, on the basis of the analysis on the nature of the coal tar, we used quinoline as model compound to select the catalyst carrier and promoters on a micro fixed bed, then prepared the coal tar HDN catalyst SDDN-12.In order to obtain a suitable catalyst support, a first screening of different sources and specifications of macroporous alumina has been done. Through comparing different supports we found the dispersion of active component on catalyst surface is differet, and the catalyst activities are slightly different. Second, on the basis of the alumina carrier selection, we changed the content of promater fluorine, then studied the impact of fluorine on the dispersion of the active phase and the activity of the catalysts. The results show that, modification of fluorine can reduce the surface area of catalyst and the dispersion of active metal. But the reduction ability of active phase is improved and the effective utilization of the active metal increased. The catalyst modified with2%fluorine can preferably balance the influence of various aspects, and it has the best HDN actity. Furthermore, we added organic complexing agent EDTA to the impregnation system, and studied the effect of EDTA on pore volume, specific surface area of catalyst and the distribution of the active phase on catalyst surface. When the EDTA/Ni=0.5, the catalyst has more efficient active component and high degree of dispersion. So it has the highest HDN activity, as the denitrification rate10%is higher than the catalyst without the addition of EDTA. On the basis of the above three parts of the experiment, we prepared coal tar HDN catalyst SDDN-12, and investigated the HDN performance of SDDN-12and commercial catalyst CAT-1. Compared with the commercial catalyst, SDDN-12has higher hydrogenation activity. We can further the investigation of the coal tar with SDDN-12.