Upgrading heavy crude oils to lighter products with a dispersed zeolite

#This invention is concerned with a catalytic process for upgrading a heavy oil. It is particularly concerned with crude oils that have a substantial wax content such as, for example, Taching Crude, and fractions thereof. The process of this invention is a catalytic process in which a relatively new type of synthetic zeolite, exemlified by ZSM-5, is employed as catalyst.

#Fuels refineries historically have shown considerable interest in converting crude petroleum to portable liquid fuels boiling below about 800.degree. F. Particular attention has been paid to processes which are capable of reducing the molecular weight of the heavier distillate fractions to high quality gasoline and middle distillates. Although initially a certain amount of so called thermal cracking was practised, this was supplanted almost entirely by highly effective catalytic processes that produced higher quality gasoline. At the present time practically all petroleum refiners who employ catalytic cracking depend on one version or another of a system in which the cracking catalyst is fluidized by the hyrocarbon feed and is converted while in that state. We shall for convenience collectively refer to these versions as the "fluid catalytic cracking process", or simply "the FCC process".

#The outstanding feature of a modern FCC operation is that it is capable of extensively converting a clean distillate feed with minimum formation of unwanted by-products. The process is designed so that the coke by-product is carried with the catalyst and is burned in a regenator to supply necessary process heat. Economy of scale is achieved by building very large plants, typically capable of processing from about 50,000 to about 250,000 barrels per day of feed. The process, however, is not without shortcomings.

#FIG. 1 of the drawing is a flow sheet illustrating the invention.

#FIG. 2 of the drawing illustrates one configuration for the reactor section .

#A wide range of hydrocarbon oil feeds may be used in the process of this invention. For example, the process may be adapted to upgrading a high pour point distillate such as that described in U.S. Pat. No. 4,067,797 issued to Chen et al Jan. 10, 1978. In that patent is described the dewaxing by a fixed bed process of an Arabian Light gas oil boiling in the range of 470.degree. to 730.degree. F. Note that the term "heavy" as used in the present disclosure and claims means a feed which contains at least 50 wt% of a fraction boiling above about 550.degree. F. at atmospheric pressure, or, alternatively, an oil that has an ASTM 50% temperature not lower than about 550.degree. F. Examples 19 to 30 of the cited Chen et al patent describes the dewaxing of the 645.degree. to 750.degree. F. portion of the wider cut Arabian Light gas oil, and this fraction clearly illustrates a heavy, waxy hydrocarbon oil feed within the scope of the present invention. For purposes of the present invention, a hydrocarbon oil that has an ASTM 50% temperature lower than about 550.degree. F. often may be fractionated to provide a suitable heavy hydrocarbon feed. The entire content of U.S. Pat. No. 4,067,797 is incorporated herein by reference.

#The heavy Arabian Light gas oil illustrated above, being a distillate, represents a very high quality feed substantially free of metals. Such a feed utilized in the present invention will be characterized by demanding a relatively small circulating inventory of catalyst and low catalyst consumption, as will be more fully described hereinbelow.

#Other feeds that may be used in the process of this invention include waxy whole crudes, topped crudes, vacuum gas oils, and, in general, any hydrocarbon oil derived from petroleum, coal, shale, or from another source, providing that the oil has an ASTM 50% temperature not lower than about 550.degree. F. U.S. Pat. No. 4,263,126 to Rollmann cited above discloses the properties, including the composition, and the conversion of virgin Taching whole crude. It is noted therein in Example 1 that 60.5% of the crude is a residual oil fraction boiling above 800.degree. F., and therefore a heavy oil within the scope of this invention. Thus, the hydrocarbon oil feed utilized on the process of this invention may contain a residual fraction. The Taching crude, unlike the Arabian Light distillate contains metals. Therefore, when this type of feed is used, the circulating inventory of catalyst will be relatively large, and to control catalyst consumption, it will be required to regenerate all or part of the circulating inventory of catalyst, as more fully described herein below.