Study On Hydro-upgrading Of Residue In The Presence Of Unsupported Catalysts

The global reserves of heavy oil are great, the crude oil resources are becomingincreasingly heavier, the consumption demands for transportation fuel are progressivelyincreased and the environmental requirements on oil quality are more and more stringent.These factors promote the development of heavy oil hydrogenation processes and the study ofhydrogenation catalysts. Unsupported catalysts, active site density of which is much higherthan traditional supported hydrogenation catalysts, are more and more widely used for its ultrahigh hydrogenation desulfurization, denitrogenation and aromatics saturation activity.In this paper, a series of unsupported hydrogenation catalysts were made and thehydro-upgrading performance of Shengli VR in autoclave was studied. It was showed that thethree-componential NiMoW unsupported catalyst had higher Shengli VR hydro-upgradingcapacity than two-componential NiMo and NiW unsupported catalyst. The heteroatomsremoval performance of unsupported catalysts could be further improved by increasing theratio of binder and improving the pore properties.In the presence of NiMoW unsupported catalyst, effect of reaction and catalystconditions on Shengli VR hydro-upgrading reaction was studied. It was showed that thermalcracking reactions occurred in the vacuum residue hydro-upgrading process. Increasingprocess temperature, reducing the initial hydrogen pressure, longer reaction time, improvedthe conversion of VR, resulted in the increasing yield of gasoline, diesel and VGO. Theunsupported catalyst could promote the removal of heteroatoms while inhibit the formation ofcoke. As the support of coke deposition, the unsupported catalyst avoided the coking onautoclave wall.Considering the vacuum residue conversion, the amount of coke and the removal of the S, N, Ni, V-heteroatom, it was decided that the optimal process parameters for Shengli VRhydrogenation reaction in the presence of unsupported catalysts were as followed: thereaction temperature was400℃, the initial hydrogen pressure was8MPa, the reaction timewas2h, the catalyst addition was5%and the catalyst particle size was40-60mesh. Underthese parameters, the hydro-upgrading results were as followed: the VR conversion was54.2%, the sum of gasoline and diesel yield was22.6%, the VGO yield was29.1%and thecoke yield was0.51%. The S, N, Ni, V-heteroatom removal rate was73.7%,24.5%,66.9%,80.5%respectively.Under the optimal process parameters, the hydrogenation conversion results of DaqingVR, Gudao VR, Shengli VR, Shaqing VR and Weinei VR showed that: the vacuum residuewith more asphaltene got higher conversion and higher coke yield, its vacuum residuefractions of hydrogenation products were more inferior. Residue hydro-upgrading process inthe presence of unsupported catalyst was more suitable for processing middle-sulfur,low-nitrogen and low-metal residue, such as Gudao VR.