FI62819C - FOER FRAMEWORK CONVERSION AV EN KEROSENFRAKTION TILL JETBRAENSLE - Google Patents

Description

FSSF * 1 [8] (11) NOTICE A9ftl0 UTLAGGNI NGSSKRIFT OZO I 7 C (45And issued on 10 03 1933

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_. . (44) Date of dispatch of the decision. -

Patent · och ragisterstyreiaan AmMcm utkgd oeh utUkrtfwn puMkerad 30.11.82 (32) (33) (31) PyH · tty acuoMcau · —Begird priorket 13.H.72 USA (US) 305975 (71) The Lummus Company, 1515 Broad Street, Bloomfield, Rev Jersey 07003, USA (72) Morgan C. Sze, Upper Montclair, RJ, James W. Reilly, Westfield, NJ, USA (74) Berggren Qy Ab (54) Method for converting a fuel oil fraction to jet fuel - This invention relates to a Friedel-Crafts-type process for converting or refining a fuel oil fraction from a catalytic jet engine fuel. More specifically, this invention relates to a process for converting or refining a fuel oil fraction using a catalyst containing a Group VIII noble metal supported on a refractory oxide and an aluminum halide.

In Friedel-Crafts processes, the conversion of hydrocarbons is promoted using a catalyst containing aluminum halide, usually aluminum chloride or aluminum bromide. The original work of Friedel and Crafts involved the preparation of ketones by reacting benzene with acyl halides in the presence of aluminum chloride. During the 1930s and 1940s, and especially during World War II, large oil companies in particular conducted extensive research into this type of process and this catalyst system in general. This study mainly aimed at the use of such processes for the production of gasoline, the isomerization of normal paraffins to branched chain paraffins and the alkylation of aromatic and paraffinic compounds with olefins. To a lesser extent, work was done on other processes, such as the isomerization of cycloparaffins. Previously, aluminum chloride had been used in catalytic cracking processes. The first work during the 1930s and 1940s involved the invention of Friedel-Crafts catalysts containing only aluminum halide; then supported aluminum halides were invented. Further development led to the invention of catalysts containing aluminum halides with free aluminum, double salts of aluminum halides, aluminum halides with additives and organic complexes of aluminum halide. In a few patents involving only either aluminum halides or mixtures of aluminum halide and free aluminum, the aluminum halide itself was prepared in the hydrocarbon conversion zone by reacting the aluminum metal with halogen or halogen, which was fed either separately or mixed to the feed mixture. However, for the most part, work with such a system does not appear to have proceeded, except in connection with the alkylation of paraffinic hydrocarbons with olefins. In most of the literature, the aluminum halide catalyst was fed as such to the reaction. Much of the literature, particularly the patent literature, relates to methods for preparing supported aluminum halide catalysts by an improved impregnation process, particularly by sublimation of aluminum halides into the pores of the support.

Following this work, interest developed in the use of Group VIII noble metal catalysts to which halogen had been added to perform this type of hydrocarbon conversion reaction.

More recently, it has been proposed to use catalysts containing a Group VIII noble metal supported on alumina impregnated with both added halogen such as hydrogen halide and aluminum halide. The aluminum halide component is generally incorporated into the catalyst in vapor form by sublimation and impregnation of the sublimated vapors into the pores of the support.

It is an object of the present invention to provide a process for converting a fuel oil fraction to a jet engine fuel using an improved Group VIII noble metal, support and aluminum halide.

The main features of the invention appear from the appended claims.

The invention is illustrated by the accompanying drawings, in which: Figure 1 shows a flow chart illustrating the manufacture of jet fuel utilizing the present invention; 3 6281 9 Figure 2 shows an arrangement of catalyst components in a reactor in which a layer of aluminum metal is placed above a packed layer containing a noble metal catalyst supported on a refractory oxide; Figure 3 includes an alternative arrangement of a catalyst in a reactor in which a supported noble metal component is mixed with aluminum metal; and Figure 4 shows a catalyst arrangement similar to that of Figure 2, except that the hydrocarbon feed is passed past an aluminum metal layer.

In general, the process of the invention is carried out by passing a fuel oil fraction and a halogenating wave selected from the group consisting of hydrogen halides, halogens and mixtures thereof to a reaction zone containing metallic aluminum and a catalyst layer containing a Group VIII noble metal supported on a refractory oxide. Hydrogen can also be fed to the reaction zone either in significant amounts to participate in the main reaction, such as in hydrogenation processes, or in small amounts if needed to control the formation of unwanted by-products. The aluminum metal is contacted with a halogenating agent to form the corresponding aluminum halide. The aluminum halide then continuously combines with the physically supported noble metal catalyst to form a supported catalyst containing the noble metal and the aluminum halide. This generation of the aluminum halide component in the reaction zone itself provides replenishment of the unchanged freshly generated aluminum halide catalyst, allowing the reaction to proceed at a substantially constant rate for a considerable period of time.

Figure 1 shows a flow chart for the production of jet fuel. The hydrocarbon feed through line 1 is mixed with the recycle mixture from tube 8 below and the combined stream passes through line 3 to reactor 10. Depending on the origin of the feed mixture, preheating of the combined stream in tube 3 may be necessary to bring it to 121-232 ° C, preferably 149-204 ° C. This can easily be accomplished in the heat exchanger 12 by exchanging heat with the reaction products or in some other way that may be desirable. It is recommended to mix a halogenating agent, such as hydrogen halide, e.g. hydrogen chloride, in the feed mixture from the pipe 2 after preheating or alternatively to be fed separately to the reactor via the pipe. The mixture stream, which contains the feed, the circulating mixture and in most cases the halogenating agent, is fed to the upper end of the reactor 10.

“62319

In reactor 10, normal paraffins are isomerized to iso-paraffins under hydrogen pressure and unsaturated compounds (i.e., aromatics and olefins) are hydrogenated to the corresponding saturated compounds (naphthenes and paraffins, especially isoparaffins). Compared to most of the other processes described above, the amount used to produce jet engine fuel requires significant amounts of hydrogen. Even when hydrogen halide is used as the halogenating agent, the amount of hydrogen generated by the reaction between hydrogen halide and aluminum is not sufficient to effect the desired degree of hydrogenation. Thus, more hydrogen must preferably be fed to the bottom of the reactor through pipe 5A, whereby it comes into countercurrent contact with the hydrocarbon mixture.

The liquid product is removed from the bottom of the reactor via a pipe 6 and cooled in a heat exchanger 12. As described above, the heat exchanger 12 can also be used to preheat the feed to the reactor.

Gaseous products comprising volatile hydrocarbons, excess hydrogen and halogenating agent are removed from the top of the reactor via line 9, cooled in heat exchanger 16 and separated in separator 18 into a liquid product containing hydrocarbons and a gaseous product containing predominantly hydrogen and halogenating agent. The liquid product is recycled via line 8 to the reactor feed mixture. The gaseous products are transferred via line 10 to scrubber 20 and released into the atmosphere (line 13) and / or waste (line 11).

Another advantage of the present invention is that it can be performed under relatively mild temperature and pressure conditions. The feed temperature is between about 121-204 ° C, preferably between 149 and about 204 ° C. The temperature in the reactor ranges from about 121 ° C to about 316 ° C, preferably from about 177 to about 260 ° C and the pressure is from about 21 to 84 kp / cm 2, preferably from about 28 to 70 kp / cm . Significant cooling effect and consequent temperature control is achieved by transferring the heat of reaction by sensitive heating of both liquids and gases in the reactor and evaporation of the liquid as well as by feeding "cold" hydrogen without preheating to the reactor. The ratio of recycling to fresh feed is about 0.05-1.00, preferably 0.10-0.50.

When using this process for the production of jet fuel, it is not detrimental to use the reactor-catalyst system shown in Fig. 3, in which the feed comes into contact with the aluminum halide just prepared. Any cracking that may occur as a result of this contact tends to produce more isoparaffins that are beneficial to the quality of the product. The temperature control in the process prevents uncontrolled reactions leading to the formation of unwanted cracking by-products such as coke.

6281 9 5

Figure 2 shows an embodiment of the arrangement of the catalyst components in the reactor. The feed mixture in the tube 3, which contains a hydrocarbon plus a halogenating agent, enters the top of the reactor through the feed opening 36 and passes through the gas distributor 30 to the aluminum-metal layer 32, which is preferably in the form of spheres. The halogenating agent in the feed mixture reacts with the aluminum metal to form an aluminum halide which flows downward together with the feed to a packing layer 34 containing a Group VIII noble metal catalyst such as platinum supported on a refractory oxide such as alumina. The hydrocarbon then reacts with the supported aluminum halide noble metal catalyst to form the desired products which can be removed along line 6. If hydrogen is to be used, it can be fed either parallel to the feed mixture in the pipe 5 or in the pipe. 3A countercurrent to the feed mixture. Any excess hydrogen is removed along line 9, which can act to remove other gaseous substances from the reactor.

Figure 3 shows an alternative embodiment of the catalyst system of the invention in which there is no separate aluminum metal layer 32, but aluminum spheres are applied to the entire supported noble metal catalyst filler layer 34. The aluminum halide formed in the bed is continuously mixed with the catalyst system. In some cases, this system has been found to be better than that shown in Figure 2 in that it tends to reduce cracking that may result from direct contact of some feed mixtures with pure aluminum chloride before they reach the catalyst filler layer 34.

Figure 4 shows a preferred embodiment for certain processes in which cracking is further reduced. In this figure, the hydrocarbon feed mixture enters space 42 through the feed port li0 at the top of the reactor. The aluminum layer 32 is covered with a plate or septum 43 having tubes or channels 44 extending therethrough and passing through the aluminum layer opening to the noble metal alumina catalyst filler layer 34. The hydrocarbon feed is passed through the tubes 44 to the filler layer 34 bypassing the aluminum layer 32. In this embodiment halogen before it enters the reactor, but is fed from the pipe 4 through the feed opening 4'5 directly to the aluminum metal layer 32, where it converts it into an aluminum halide which flows downwards into the packed bed of the supported noble metal catalyst 6 6281 9. Thus, the hydrocarbon feed does not come into contact with the newly formed aluminum halide.

The aluminum halide generated during the operation of the process may be any aluminum halide known to be suitable as a Friedel-Crafts catalyst, such as aluminum chloride, aluminum bromide and mixtures of chlorides and fluorides and other mixtures of aluminum halides. Aluminum chloride is the preferred compound. The aluminum metal can be used in any suitable form, e.g., powder, spheres, granules, etc., and is generally used in an amount of 1 to 5% by weight of the total amount of catalyst charge.

The aluminum halide is formed by a reaction between aluminum and a halogenating agent, which halogenating agent may be hydrogen halide, free halogen or mixtures thereof. Particularly suitable are hydrogen chloride, hydrogen bromide, chlorine, bromine (in the vapor state) and mixtures of hydrogen chloride and hydrogen and hydrogen bromine and bromine. Preferred halogenating agents are hydrogen halides, especially hydrogen chloride. The use of hydrogen halide has at least two advantages over free halogen. The reaction of hydrogen halide with aluminum produces hydrogen, which can act as a reagent, for example, in the production of jet fuel or in the prevention of the formation of unwanted by-products. Second, the catalyst support does not need to be impregnated with halogen, as is usually done, as any excess hydrogen hydrogen that is not required for the reaction with aluminum acts as a substitute for impregnation.

This can aid in catalyst activity in several processes. The halogenating agent is added to the system as needed to maintain the activity of the catalyst and is usually in the ppm range based on the fresh feed.

The noble metal component of Group VIII of the catalyst is selected from the platinum group; i.e. platinum, palladium, ruthenium, rhodium, osmium and iridium. Platinum and palladium are the preferred metals. The refractory oxide is a solid and can be selected from a wide variety of oxides that are not necessarily equivalent supports. Suitable refractory oxides include various materials such as alumina, titanium dioxide, zirconia, chromium oxide, zinc oxide, silicon alumina, chromium alumina, aluminum chlorine oxide, silicon zirconium oxide, and various naturally occurring refractory oxides such as bauxite.

The Group VIII noble metal is coupled to the support by any suitable technique known in the art and is present in the catalyst in elemental form.

7 6231 9 The preferred catalyst system for use in the processes of this invention contains platinum supported on alumina to which is added aluminum chloride generated in the reactor itself by reacting the aluminum with hydrogen chloride.

The generation of the aluminum halide portion of the catalyst in the reactor itself is advantageous when carrying out hydrocarbon conversion processes in which the fuel oil is converted to jet fuel as described below.

The present invention relates to a new process for the production of high quality jet fuel from a combustible oil fraction, comprising jet fuels for use in both conventional and supersonic aircraft. Current specifications for jet fuel used in faster-than-airplanes require a freezing point of at least -49 ° C, a luminometric value (ASTM Designation D-1322-54T). which is at least 79 and / or a smoke point of at least 35. Such fuels are also required to have a low aromatic content (preferably less than 1.0 vol.), high thermal stability and a high calorific value. Some few varieties of fire oil are usually suitable as jet engine fuel without further processing; however, most need to be improved. Various methods have been developed for the preparation of jet fuel from fuel oil fractions by isomerization, hydrogenation and hydrocracking alone or in combination of two or more. For example, U.S. Patent No. 3,420,769 discloses a two-step process for preparing jet fuel for faster airborne aircraft by isomerization followed by hydrogenation of petroleum distillate.

It has now been found that by using this invention to provide a catalyst containing a noble metal supported on a refractory oxide and an aluminum halide generated in the reactor itself, jet fuel, including jet fuel hydroisomerization and hydrogenation process.

The term "fuel oil fraction" means a hydrocarbon fraction boiling to the final point of 288 ° C and having an initial boiling point high enough to give a flash point of at least 38 ° C. This fraction can be a straight-run petroleum distillate or can be obtained from a suitable hydrocarbon conversion process such as hydrocracking, catalytic cracking, thermal cracking, etc. In virtually all cases, the fuel oil fraction must be desulfurized before treatment because the sulfur reacts with and destroys the aluminum halide portion of the catalyst.

The following illustrative example is provided to facilitate an understanding of the nature of the present invention:

Example 1

The liquid jet fuel oil fraction was first impregnated with hydrogen chloride by passing a stream of dry HCl gas through it.

The HCl concentration in the feed was 5360 ppm. The mixture was preheated, stirred with make-up hydrogen, heated to feed temperature (120-123 ° C) and fed to the reactor. The reactor was operated at a maximum temperature of 200-201 ° C 2, a pressure of 35 kp / cm and a volumetric flow rate (L.H.S.V.) of 0.7-

Example 2

The liquid jet engine fuel oil fraction (containing dissolved water) was saturated with hydrogen chloride by bubbling for one hour before it was fed to the reactor. The HCl content in the feed-jet engine fuel oil was determined by extraction and titrated with 0.01 N base and found to be 5360 (w / w) ppm. The arrangement of the catalyst in the reaction vessel is shown in Figure 3 and had a layer of aluminum pellets (16 mm deep) on a mattress of platinum-coated aluminum catalyst tablets with a total depth of 30 cm. The weight ratio of Pt / aluminum to aluminum metal was 33.6 / 1.

The liquid hydrocarbon feed (with dissolved water and hydrochloric acid) was pumped to system pressure, preheated and mixed with hydrogen gas and charged to the top of the reactor. The inlet temperature of the catalyst bed (immediately at the top of the aluminum pellet layer) was maintained at 120-123 ° C. The feed rates for liquid jet engine fuel oil and hydrogen gas were 210 cm 2 / h (specific gravity = 0.8 L) and 0.2 SCP / h. Upon direct contact of the aluminum pellet layer, a reaction between HCl dissolved in the hydrocarbon (in the presence of dissolved water) and metallic aluminum was obtained, resulting in aluminum chloride. This active Grignard mixture was then fed to a platinum-coated main aluminum catalyst mattress, where it physically merged with the platinum-coated aluminum tablets. The inlet temperature was maintained at 120-123 ° C and the maximum temperature of 200-201 ° C was reached at a depth of 15 cm. The catalyst bed discharge temperature was 154-159 ° C. The reactor pressure was adjusted during the 35 ata experiment with hydrogen gas to minimize side reactions such as cracking and coke formation.

Examination of the feed mixture and the product for the properties required for improved performance in faster airplanes yielded the following results: