Virgin naphtha

Isomerization. Isomerization is a catalytic process which converts normal paraffins to isoparaffins. The feed is usually light virgin naphtha and the catalyst platinum on an alumina or zeoflte base. Octanes may be increased by over 30 numbers when normal pentane and normal hexane are isomerized. Another beneficial reaction that occurs is that any benzene in the feed is converted to cyclohexane. Although isomerization produces high quahty blendstocks, it is also used to produce feeds for alkylation and etherification processes. Normal butane, which is generally in excess in the refinery slate because of RVP concerns, can be isomerized and then converted to alkylate or to methyl tert-huty ether (MTBE) with a small increase in octane and a large decrease in RVP. 

Virgin Naphtha Catalytic Reforming (Powerfortning) This technique is used for the production of high octane motor gasoline, or as a source of aromatic compounds. 

Hydrofining is applied to virgin naphthas mainly in the form of a pretreatment step for the feed to catalytic reformers (Powerforming). Sulfur levels of 5 parts per million (ppm) or less are required to avoid deactivation of the platinum reforming catalyst. 

Virgin naphtha hydrofining processing conditions have been standardized at 550°F, 4 V/hr/V, 300-400 psig and 400-500 SCF/B of 70% H treat gas. Such conditions will make a 4 ppm sulfur product of most stocks of interest. 

Aromatics are petrochemicals. Fixed-bed reforming of virgin naphthas is one source of these materials. Aromatics fiom the high temperature of coking of coal, the main source prior to 1940, now only account but for a small proportion of the total production. 

Powerforming is one tecnique used for aromatics chemical production. Powerforming uses a platinum catalyst to reform virgin naphthas. The principal reaction is the conversion of naphthenes in virgin naphthas to aromatics e.g., isomerization and dehydrocyclization reactions also occur in catalytic reforming. 

The virgin naphtha feed after having been hydrofined over a cobalt molybdenum catalyst to remove sulftir compounds passes through the Powerformer. After stabilization, the aromatics are recovered by extracdon with... 

Aviation gasoline contains a high concentration of alkylate and high-octane-number aromatics. Careful fractionation of virgin naphtha can also be performed to isolate isohexane and isoheptane fractions. Aromatic components are limited by their calorific value and are typically C and Cg. 

Figure 2. Conventional Fixed-Bed Hydroforming of Various Virgin Naphthas...

F. virgin naphtha (predominantly East Texas). Kellogg MoOi on AlsOt gel catalyst]... 

In view of these considerations, a large amount of effort is reported in the scientific press on the development of a process to produce benzene from n-hexane by combined cyclization and dehydrogenation. w-Hexane has a low Research octane number of only 24.8 and can be separated in fair purities from virgin naphthas by simple distillation. Recently, an announcement was made of a process in the laboratory stage for aromatiza-tion of n-hexane (16). The process utilizes a chromia-alumina catalyst at 900° F., atmospheric pressure, and a liquid space velocity of about one volume of liquid per volume of catalyst per hour. The liquid product contains about 36% benzene with 64% of hexane plus olefin. The catalyst was shown to be regenerable with a mixture of air and nitrogen. The tests were made on a unit of the fixed-bed type, but it was indicated that the fluid technique probably could be used. If commercial application of this or similar processes can be achieved economically, it could be of immense help in relieving the benzene short-age. 

The new developments in catalyst improvements and in process optimization have brought new opportunities to directly process virgin naphtha from atmospheric distillation along with benzene and benzene precursors extracted from reformer feeds. This can eliminate the need for a separate naphtha hydrotreater as well as sepa-... 

Carbon Hydrocarbon number structure Virgin naphtha Thermal naphtha Catalytic naphtha Thermodynamic equilibrium at 470°C. ... 

Naphtha hydrotreater Vapor phase catalytic Remove S and N from catalytic and virgin naphtha before catalytic reforming... 

Symposium on Nonhydrocarbon Constituents of Petroleum), 121st Meeting, American Chemical Society, Milwaukee, Wis., p. 97. The Identification of Cyclohexanethiol in Virgin Naphthas. 

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