“…Adding catalysts to the heavy oil slurry-phase hydrogenation reaction system is a very effective way to inhibit coke formation. These catalysts are mainly of two forms, solid powder catalysts and dispersed catalysts, − and the active components of these catalysts are generally transition metals of the IVB, VB, VIB, VIIB, and VIII families, such as cobalt, molybdenum (Mo), nickel (Ni), and iron. − Although Ente Nazionale Idrocarburi (ENI) has industrialized this technology, researchers and research institutions still continue to investigate the catalysts to improve the catalytic efficiency and reduce the costs, thereby improving the technical economy of this process. − However, in the slurry-phase hydrogenation reaction, the catalyst that is preferably dispersed in the raw material is likely to agglomerate during the heating process or the initial stage of the reaction to produce a large particle diameter. , Such agglomeration seriously affects the catalytic activity and the efficiency of use of metals because it is difficult for the metals inside the catalyst particles to contact the feedstock oil or H 2 to exert their activities of hydrogenation and coke inhibition, which is consistent with the results reported in the refs and ; that is, taking Mo catalyst as an example, the hydrogen evolution activity of MoS 2 is proportional to the number of edge sites on its outer surface, and the MoS 2 , which can exert hydrogen evolution reaction activity accounts for only a small portion of the entire MoS 2 . Therefore, designing a catalyst with a hollow structure , may improve this phenomenon because the active metal will be distributed in the shell of the hollow structure catalyst, thereby increasing the utilization of the metal.…”