In vacuum gas oil

The aromatics in vacuum gas oil may contain one to six fused aromatic rings that may bear additional naphthene rings and alkyl substituents in keeping with their boiling range. Mono- and di-aromatics account for about 50% of the aromatics in vacuum gas oil samples. 

Coprocessing of waste plastics with heavy petroleum fractions have considerable interest in feedstock recycling. In this study, we aimed to investigate the processing of municipal waste plastics (MWP) in presence of conventional and non-conventional catalysts in a refinery stream. For this purpose, the hydrocracking of MWP in vacuum gas oil (VGO) over metal loaded active carbon and conventional acidic catalysts (HSZM-5, DHC-8) was carried out to obtain liquid fuel. 2 refs. 

S. Karagoz, J. Yanik, S. Ugar, M. Sa-lam and C. Song. Catalytic and thermal degradation of high-density polyethylene in vacuum gas oil over non-acidic and acidic catalysts. Applied Catalysis A General, 242, 51-62 (2003). 

Besides the fully unsaturated 5 f-l,4-dioxepin (45), the unsaturated 1,4-dioxepins, 6,7-dihydro-5Ef-l,4-dioxepin (46), and 2,3-dihydro-5 f-l,4-dioxepin (47), incorporate either the structural feature of an enediol ether or an enol ether. One general method for the preparation of seven-membered rings of type (46) involves ring expansion thus, treatment of 2-(methoxymethyl)-l,3-dioxane with dodecylbenzenesulfonic acid in vacuum gas oil at 250 °C and simultaneous distillation gave (46) with 69% conversion and 84% selectivity. Several 6,6-disubstituted derivatives (49), which have found interest as intermediates for agrochemicals, drugs, and plastics, have analogously been... 

Modelling diffusion, reaction and deactivation in FCC catalysts becomes important as new trends in vacuum gas oil processing point to short catalyst/oil contact times (less than 1 sec) in industrial riser reactors. Under short contact times catalysts particles may experience diffusion limitations [6], and thus catalyst pore dimensions become very important in determining conversion and selectivity. FCC catalysts are made of several different components to produce the necessary activity and mechanical properties. As the accessibility of large molecules to the active sites within the catalyst might be constrained,... 

When I had instructed the crude unit operators to reduce vacuum tower wash oil by 50%, the entrainment of resid or tar into the gas-oil FCCU feed had substantially increased. As shown in the above tabulation of laboratory data, the entrainment had caused an increase in conradson carbon residue of the vacuum gas oil. This was of no consequence. The extra coke made due to the higher conradson carbon was compensated for by cutting the FCCU feed preheat temperature to hold the regenerator in heat balance. Of greater importance was the increase in nickel content from 0.5 ppm in vacuum gas oil to 2.0 ppm. This fourfold multiplication in nickel content was reflected by a concurrent increase of nickel accumulation of the circulating catalyst. As the nickel content of the catalyst increased. 

In vacuum gas oils and other 650°F-plus (343°C-plus) material, more than half of the carbon atoms may be found in ring compounds - polyaromatic hydrocarbons (PAH), partially saturated PAH (naphthene-aromatics) and fully saturated naphthenes. According to Qader and McOmber and Lapinas, et al., ° hydrocracking converts complex ring compounds into light products by the following sequence of reactions ... 

Organo-metallic compounds contained in the feed will be decomposed and the metals will be retained on the catalyst, thus decreasing its activity. Since metals are normally not removable by oxidative regeneration, once metals have poisoned a catalyst, its activity cannot be restored. Therefore, metals content of the feedstock is a critical variable that must be carefully controlled. The particular metals which usually exist in vacuum gas oil type feeds are naturally occurring nickel, vanadium and arsenic as well as some metals which are introduced by upstream processing or contamination such as lead, sodium, silicon and phosphorous. Iron naphthenates are soluble in oil and will be a poison to the catalyst. Iron sulfide as corrosion product is normally not considered a poison to the catalyst and is usually omitted when referring to total metals. 

Thermal Cracking. In addition to the gases obtained by distillation of cmde petroleum, further highly volatile products result from the subsequent processing of naphtha and middle distillate to produce gasoline, as well as from hydrodesulfurization processes involving treatment of naphthas, distillates, and residual fuels (5,61), and from the coking or similar thermal treatment of vacuum gas oils and residual fuel oils (5). 

As is indicated in Figure 4, saturates contribute less to the vacuum gas oil (VGO) than the aromatics, but more than the polars present at percentage, rather than trace, levels. VGO itself is occasionally used as a heating oil but most commonly it is processed by catalytic cracking to produce naphtha or by extraction to yield lubricant oils. 

Steam Cracking. Steam cracking is a nonselective process that produces many products from a variety of feedstocks by free-radical reactions. An excellent treatise on the fundamentals of manufacturing ethylene has been given (44). Eeedstocks range from ethane on the light end to heavy vacuum gas oil on the heavy end. All produce the same product slate but in different amounts depending on the feedstock. 

Deep C t lytic Crocking. This process is a variation of fluid catalytic cracking. It uses heavy petroleum fractions, such as heavy vacuum gas oil, to produce propylene- and butylene-rich gaseous products and an aromatic-rich Hquid product. The Hquid product contains predorninantiy ben2ene, toluene, and xylene (see BTX processing). This process is being developed by SINOPEC in China (42,73). SINOPEC is currentiy converting one of its fluid catalytic units into a demonstration unit with a capacity of 60,000 t/yr of vacuum gas oil feedstock. 

Effect of Feed Rate The effect of feed rate on hydrodesulfiirization of vacuum gas oil is shown in Figure 3. Halving the feed rate in this range approximately halves the product sulfur. 

An RFCC is distinguished from a conventional vacuum gas oil FCC in the quality of the feedstock. The residue feed has a high coking tendency and an elevated concentration of contaminants. 

Heavy fractions (e.g., vacuum gas oils) and residues HDP might involve both, hydrotreatment and hydrocracking operations. HDT, in this case, is a feed pretreatment, for preparation to another process unit, which might be a HCK unit. This process combination, HDT-HCK can be used on Cycle Oil (FCC, coker), VGO (SR and coker) and SR residues (atmospheric and vacuum). It can be carried out in a single reactor with more than one catalyst, or in more than one reactor. 

VGO Isomax [Vacuum gas oil] A hydrodesulfurization process adapted for treating vacuum gas oil, a petroleum fraction. Developed by Chevron Research Company in the early 1970s. In 1972, five plants were in operation and six were under construction. See also RDS Isomax and VRDS Isomax. 

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