Asphaltene organometallics

Physical methods of fractionation of tar sand bitumen usually indicate high proportions of nonvolatile asphaltenes and resins, even in amounts up to 50% wt/wt (or higher) of the bitumen. In addition, the presence of ash-forming metallic constituents, including such organometallic compounds as those of vanadium and nickel, is also a distinguishing feature of bitumen. 

Sulfur Compounds — Oxygen Compounds—Nitrogen Compounds — Organometallic Compounds Resins and Asphaltenes 40... 

Nickel and vanadium in petroleum exist as soluble organometallic complexes that fall into two categories metal porphyrins and nonporphyrin metal complexes. Both the porphyrins and the nonporphyrins may be distributed over a wide boiling range (350-650°C+), reflecting significant variations in molecular weight, structure, and polarity. Metal porphyrins and nonporphyrin metal complexes also tend to precipitate as part of the asphaltene materia] to an extent that varies with the source of the crude oil. 

Distillation concentrates the metallic constituents in the residua (Table 3-5) some can appear in the higher-boiling distillates but the latter may, in part, be due to entrainment. Nevertheless, there is evidence that a portion of the metallic constituents may occur in the distillates by volatilization of the organometallic compounds present in the petroleum. In fact, as the percentage overhead obtained by vacuum distillation of reduced crude is increased, the amount of metallic constituents in the overhead oil is also increased. The majority of the vanadium, nickel, iron, and copper in residual stocks may be precipitated along with the asphaltenes by low-boiling alkane hydrocarbon solvents. Thus, removal of the asphaltenes with n-pentane reduces the vanadium content of the oil by up to 95% with substantial reductions in the amounts of iron and nickel. 

The effect of elemental sulfur and organic sulfur compounds and organometallics on the mesophase microstructure was investigated. Elemental and organic sulfur coiqtounds and organometallic compounds were added to Catalytic Incorporated coal liquid asphaltene and A240 petroleum pitch. 

The cross polarized micrographs of the pyrolyzed residues of the Cat. Inc. original coal liquid and Cat. Inc. asphaltene are shown in Figure 2. The microstructures are primarily coarse mosaic textures. The following subsections describe the different additives of elemental and organic sulfur, organometallics and their combined effects on Cat. Inc. asphaltene during pyrolysis. 

The effect of organometallics at 1600 ppm and 800 ppm on the pyrolysis residues of the Cat. Inc. asphaltene are shown in Figure 5 and Table IV. The additives used were mentioned in the experimental part. Table IV shows that organic Hi and V inhibit mesophase formation because they promote dehydrogenation and condensation reactions to a greater extent than the other listed additives. Pyrolysis yields are increased because of increased... 

Table IV. Effect of Organometallics Added to Cat. Inc. Coal Liquid Asphaltene...

The combined effects of organometallic additives at 1600 ppm and 800 ppm with 6Z by weight organic sulfur, exemplified by dibenzothiophene (DBT), on the Cat. Inc. asphaltene are shown in Table V and Figure 6. It is shown that the microstructures stay unchanged except for the Hi addition. Also the pyrolysis yield is increased over that of Cat. Inc. asphaltene and 6Z organic sulfur without the organometallic additives. The effect of... 

The influence of organic enlfnr (M by weight) with organometallic compounds on mesophase formation in Cat. Inc. asphaltene. 

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