US3784622A - Saturated hydrocarbon averaging - Google Patents

Abstract

A PROCESS FOR PRODUCING LIGHT HYDROCARBONS AND JET FUEL BOILING RANGE PARAFFINIC HYDROCARBONS WHICH COMPRISES AVERAGING A RAFFINATE RICH IN PARAFFINS WITH ANOTHER PARAFFINIC FEEDSTOCK SELECTED FROM THE GROUP CONSISTING OF PROPANE OR C4 TO C10 TO C20 HYDROCARBONS OR MIXTURES OF THE FOREGOING HYDROCARBONS, TO OBTAIN AT LEAST C5 AND C10+ HYDROCARBONS.

Description

United States Patent 3,784,622 SATURATED HYDROCARBON AVERAGING Thomas R. Hughes, Orinda, Calif., assignor to Chevron Research Company, San Francisco, Calif.

No Drawing. Continuation-impart of applications Ser. No. 864,870 and Ser. No. 864,871, both Oct. 8, 1969, both now abandoned, Ser. No. 3,303 and Ser. No. 3,306, both Jan. 16, 1970. This application Sept. 14, 1972, Ser. No. 289,036

Int. Cl. C07c 5/18 US. Cl. 260-676 R 6 Claims ABSTRACT OF THE DISCLOSURE A process for producing light hydrocarbons and jet fuel boiling range paraflinic hydrocarbons which comprises averaging a raffinate rich in parafiins with another paraffinic feedstock selected from the group consisting of propane or C or C to C hydrocarbons or mixtures of the foregoing hydrocarbons, to obtain at least C and 0 hydrocarbons.

CROSS-REFERENCES This application is a continuation-in-part of now aban-. doned applications Ser. Nos. 864,870 and 864,871 filed Oct. 8, 1969, and also of applications Ser. Nos. 3,303 and 3,306, filed I an. 16, 1970. The disclosures of the four applications cited above are incorporated by reference into the present patent application.

BACKGROUND OF THE INVENTION The present invention relates primarily to averaging or the reaction of hydrocarbons of different molecular weight together in the presence of a catalyst to obtain new hydrocarbons. The present invention particularly relates to averaging alkane hydrocarbons.

The term averaging is used in this specification to mean conversion of feed components or hydrocarbon molecules of different molecular weight to at least components of intermediate molecular weight relative to the respective average molecular Weights of the feed components. The term averaging is used herein to include, however, conversion to components of molecular weight higher than the average molecular weight of the heavier feed to the averaging reaction. For example, in an averaging reaction between butane and hexane, the butane and hexane are converted to hydrocarbons such as pentane, heptane, and octane.

Averaging of alkanes is discussed further in my applications Ser. Nos. 864,870, now abandoned 864,871, now abandoned. The averaging processes disclosed in Ser. Nos. 864,870 and 864,871 are preferably carried out at a relatively low temperature, usually below about 850 F. According to the aforementioned patent applications, the averaging reaction is carried out using a catalytic mass having hydrocarbon dehydrogenation activity and olefin disproportionation activity or using a catalytic mass comprising a Group VIII component and a Group VI-B component.

The present invention is particularly concerned with upgrading raflinate obtained, for example, as a sideproduct after extracting aromatics from the effluent hydrocarbons from a catalytic reforming process. Usually, the raffinate boils in the range of about C and C hydrocarbons or about 220-350 F. The raffinate is not particularly attractive as a gasoline, as the highly parafiinic railinate has a relatively low octane rating. Also, the raffinate is not particularly suitable as a jet fuel because of its relatively low boiling range. Therefore, it would be desirable to convert the raffinate to C hydrocarbons boiling in the jet fuel range and also to lighter parafiinic hydrocarbons such as C hydrocarbons which could be used to obtain relatively high octane gasoline.

Patented Jan. 8, 1974 SUMMARY OF THE INVENTION In accordance with the present invention, a process 1s provided for producing light hydrocarbons and jet fuel boiling range paraffinic hydrocarbons which comprises averaging a rafiinate rich in parafiins with another paraffinic feedstock selected from the group consisting of propane or C or C to C hydrocarbons or mixtures of the foregoing hydrocarbons, to obtain at least C and 0 hydrocarbons.

Preferably, the averaging is carried out by contacting the rafiinate with a catalytic mass having catalytic activity for parafiin dehydrogenation as well as catalytic activity for olefin averaging.

A particularly preferred catalyst for the averaging of rafiinate with other hydrocarbons fed to the averaging zone in the present invention comprises platinum on alumina and a Group VI-B metal on a refractory sup port. Preferred catalysts for use in the averaging zone in the process of the present invention are disclosed in applications Ser. Nos. 864,870, now abandoned, and 864,871, now US. Patent No. 3,593,432. It is preferred to carry out the averaging reaction at a temperature below about 850 F. and in the presence of no more than about 5 weight percent olefins.

One of the important advantages of the process of the present invention is that the process operates to convert raffinate to paraffinic C hydrocarbons which are particularly valuable for use as jet fuel. The paraffinic hydrocarbons which result from the alkane averaging reactions in the process of the present invention have a much higher ASTM moke point than aromatic hydrocarbons and therefore are particularly suitable for use as jet fuel. The term jet fuel or jet fuel boiling range hydrocarbons is used herein to mean hydrocarbons boiling in the range of about 300 F. to about 600 F. and more usually within the range of about 350 F. to 550 F.

The term C is used in the present specification to mean hydrocarbons such as normal decanes or branched C hydrocarbons and higher hydrocarbons such as C C etc. As the present invention operates by way of alkane averaging reactions, preferably under conditions including a dehydrogenation-hydrogenation catalytic component, and preferably at relatively low temperatures to avoid a substantial amount of olefins, usually the C hydrocarbons ar predominantly paraffinic hydrocarbons with smaller amounts of naphthenes and aromatics, and a very small amount of olefins. The parafiin (alkane) content of the 0 hydrocarbons produced in the process of the present invention usually is at least 90% by weight parafi'lns.

Various hydrocarbons can be averaged with the raffinate in the process of the present invention. Hydrocarbons uch as propane or iso or normal butane or heavier hydrocarbons such as any of the hydrocarbons in the range C -C or various mixtures of the above-mentioned hydrocarbons can advantageously. be averaged with the raffinate in the process of the present invention. Light hydrocarbons such as propane and C alkanes can be averaged with C and C rich raffinate to produce light hydrocarbons which can be used, in most instances after further processing, to form gasoline, and also minor amounts of jet fuel boiling range hydrocarbons. Thus, in using the C or C hydrocarbons for averaging with the raflinate, excess light hydrocarbons such as C or C, can be upgraded in value by conversion to liquid hydrocarbon including light gasoline boiling range hydrocarbons.

C to C hydrocarbons are particularly attractive for averaging with C to C raffinate because high yields of 0 jet fuel are obtained when averaging the relatively heavy C to C hydrocarbons with the typical raflinate rich in C and C parafiins. There is also a considerable amount of light gasoline boiling range hydrocarbons such as C C and C hydrocarbons produced when averaging hydrocarbons in the range C -C with raffinate composed mostly of C and C paraflins.

The term ratfinate is used in the present invention to mean any parafiin-rich hydrocarbon stream boiling mostly in the range of about C to C and having been separated from a mixed hydrocarbon stream containing a substantial amount of aromatics. Preferably, the raflinate is rich in paraffins and contains at least 50 percent paraffins by weight and preferably 70-80 percent or more paraflins by weight. Particularly preferred rafiinate for averaging in the process of the present invention are parafiinic rich raffinates obtained after extracting aromatics from the efiluent from a catalytic reforming process. Catalytic reforming processes are those reforming processes wherein a hydrocarbon feedstock, usually a naphtha boiling range feedstock, is converted in the presence of a catalyst, usually a catalyst comprising platinum on alumina, to higher octane hydrocarbons, by means of dehydrogenation and cyclization reactions.

Preferably the averaging of the raffinate with other hydrocarbons is carried out at a temperature below 850 F., and more preferably, below 800 F., and in the presence of no more than about five weight percent olefins, by contacting the raflinate and other hydrocarbon feedstock with a catalytic mass having catalytic activity for dehydrogenation of parafiins as well as catalytic activity for olefin averaging. The catalytic mass can comprise a physical mixture of catalyst particles which are active for hydrocarbon dehydrogenation and catalyst particles which are active for olefin averaging. Preferably, the catalytic mass comprises a noble metal or a noble metal compound on a refractory support, in addition to an olefin averaging component. Thus, preferred catalyst masses include platinum on alumina particles mixed with tungsten oxide on silica particles.

It is preferred in the proces of the present invention to operate the averaging reaction zone at a pressure above about 200 p.s.i.g., more preferably above about 400 p.s.i.g., and still more preferably above about 800 p.s.i.g. The elevated pressure has been found advantageous because it leads to higher conversion. The residence time of the reactant in the reaction zone increases with increasing pressure. Also, the equilibrium partial pressures of both olefin and H formed from dehydrogenation of saturated hydrocarbons rise in direct proportion to the square root of the total pressure. Thus, relatively high pressures, of the order of 500-1500 p.s.i.g., are particularly preferred.

Although preferred operating condition for the averaging reaction zone are as indicated above, broader operating conditions include a temperature between about 400 and 900 F., a pressure between 50 and 2000 p.s.i.g., and a liquid hourly space velocity between 0.5 and 5.0.

Although the present invention is primarily directed to the averaging of rafiiuates rich in paraflins with other particularly parafiinic feedstocks, the present invention can also be applied to the conversion of only raflinate feedstocks fed to the reaction zone in the process of the present invention. In this instance, the reaction is largely a disproportionation reaction as opposed to an averaging reaction. Thus, the C hydrocarbons in the raflinate are disproportionated to form hydrocarbons such as a C and a C hydrocarbon from two C parafiins in the raflinate feed. There will, of course, be some averaging between the different molecular weight hydrocarbons in the raffinate feedstock itself, but the reaction will be primarily of a disproportionation character because of the relatively narrow hydrocarbon out which typically makes up the rafiinate feedstock.

EXAMPLES (1) In this example, normal butane is averaged with a rafiinate composed primarily of C and C paraflins.

The C hydrocarbons can be obtained from various sources such as petroleum distillates or from excess butanes from hydrocracking or catalytic reforming or other refinery process operations. The ratfinate used in this example was a rafiinate left after solvent extraction of aromatics from a portion of the efiiuent from a catalytic reforming process.

The conditions used to carry out the averaging reactions included a temperature of about 800 F., a pressure of about 900 p.s.i.g., a feed rate of about 9 cubic centimeters per hour of 1 part by volume raffinate with 2 parts by volume normal butane, a liquid hourly space velocity of 1.0, and catalyst consisting of 2 parts by volume of a 0.5 weight percent platinum plus 0.5 weight percent lithium on alumina together with 7 parts by volume of 8.0% tungsten oxide (calculated as tungsten) on silica.

The feed composition and the product or result of the averaging reaction are shown in Table I below. As can be seen from Table I below, over 9% of incremental C hydrocarbons was produced and the excess butanes were substantially upgraded to light hydrocarbons boiling in the C range which could be used in the production of gasoline. A portion of the feed to the averaging reaction was also converted to very light hydrocarbons such as C and hydrocarbons. The propane can advantageously be used to produce liquified petroleum gas (LPG).

TABLE I Feed, Product wt. percent wt. percent Net change Component:

O1 0. 63 +0. 53 1. 70 +1. 70 8. 97 +8. 97 1. 05 +1. 05 22. 81 -40. 36 2. 48 +2. 48 8.26 +8. 26 3. 51 +3. 51 5. 78 +5. 78 br-C1Hn--- 0. 10 4. 50 +4. 40 n-C1H1u 0. 67 4. 30 +3. 63 br-CsHm 17. 43 9. 72 --7. 71 n-CaHra. 3. 80 2. -0. 90 br-CsH:u--- 10. 43 9. 63 0. 80 n-CnHao 1. 37 1. 19 -0. 18 br-CmHn 1. 79 6. 88 +5. 09 n-CtoHza 0. 27 0. 2G -0. 07 (311+---.....----..-...-.; 0. 98 5. 08 +4. 10

(2) In this example, a paraflinic-rich raffinate comprising mostly C and C hydrocarbons was averaged with a paraflin in the range C to C specifically n-hexadecane (C The reaction conditions were substantially the same as those used in the previous example, except that the temperature was 700 F. instead of 800 F. The feed to the reaction zone was 50 volume percent of C 43 rich raffinate containing 82.1% paratfins, 12.3% naphthenes, and 57% alkyl benzenes, and 50 volume percent n-hexadecane.

With only one pass through the reactor, over 25 weight percent of the feed was converted to material boiling between the ratfinate and n-hexadecane, specifically between aobut 350 F. and 550 F. Thus, a relatively high yield of jet fuel was obtained with only one pass operation. It is preferable to recycle most or all of the unconverted hydrocarbons boiling above 550 F. for averaging with raffinate to convert the unconverted 550 F.+ hydrocarbons to jet fuel and lighter hydrocarbons.

In the one pass operation, substantial amounts of gasoline boiling range hydrocarbons are produced in addition to the jet fuel boiling range hydrocarbons. The gasoline boiling range hydrocarbons can be withdrawn for use as gasoline blending stock or for further processing to increase the octane rating of the gasoline boiling range bydrocarbons, or the gasoline boiling range hydrocarbons can be rcycled for further averaging.

A small amount of very light hydrocarbons are produced in any case, and these vey light hydrocarbons can be used as LPG.

(3) In this example, only raifinate was fed to the averging reaction zone. The raffinate was the same as the raffinate feed used in Examplee 2. Because only rafiinate was fed to the reaction zone, the reactions were primarily disproportionation of hydrocarbon molecules such as C or C molecules. However, some averaging reactions would occur between the C and C moleculespresent in the raffinate feed.

The conditions used to carry out the conversion of the raffinate included a temperature of about 800 F., a pressure of about 900 p.s.i.g., a liquid hourly space velocity of 1.0, and catalyst consisting of 2 parts by volume of a 0.5 weight percent platinum plus 0.5 weight percent lithium on alumina together with 7 parts by volume of 8.0% tungsten oxide (calculated as tungsten) on silica.

Table II below summarizes the results from the conversion of the ratiinate as well as tabulating the feed composition of the raflinate. In one pass operation through the reactor, approximately one-tenth of the feed was converted to LPG, about one-fourth to light gasoline in the C to C range, and over one-sixth of the feed was converted to jet fuel range hydrocarbons.

In the table below, i stands for iso, n stands for normal, and br stands for branched chain. The relatively minor amounts of cyclic compounds present are included in Table H with the branched chain compounds, and cyclic compounds such as C and C naphthenes or aromatics fall in the branched chain C and C weight percents, respectively.

Although various embodiments of the invention have been described, it is to be understood that they are meant to be illustrative only and not limiting. Certain features may be changed. It is apparent that the present invention has broad application to primarily averaging reactions wherein parafiinic-rich raflinate feedstocks are averaged with other hydrocarbons. Accordingly, the invention is not to be construed as limited to the specific embodiments or examples discussed but only as defined in the appended claims.

I claim:

1. A process for producing light hydrocarbons and jet fuel boiling range parafiinic hydrocarbons which comprises reacting a rafiinate containing paraffins boiling within the range C to C with another paraflinic feedstock having parafiinic hydrocarbon molecules of different molecular weight than said raflinate and selected from the group consisting of propane, butane, or C to C paraffins in an averaging zone to obtain a product comprising hydrocarbons of intermediate molecular weight relative to said raffinate and said other paraflinic feedstock, wherein the reacting is carried out by contacting said raffinate and other paraflinic feedstock with a catalyst mass comprising a noble metal or noble metal compound on a refractory support and a Group VI-B metal compound on a refractory support, and wherein the reacting is carried out at a temperature below 800 F. and in the presence of no more than 5 weight percent olefins.

2. A process in accordance with claim 1 wherein the catalytic mass comprises platinum on alumina and a Group VI-B metal on a refractory support.

3. A process in accordance with claim 1 wherein the hydrocarbons averaged with the raflinate are C or C hydrocarbons.

4. A process in accordance with claim 1 wherein the hydrocarbons averaged with the raflinate are in the range C to C hydrocarbons.

5. A process in accordance with claim 1 wherein the averaging reaction is carried out at a temperature below 800 F. and in the presence of no more than 5 weight percent olefins.

6. A process in accordance with claim 1 wherein the averaging reaction is carried out at a temperature between 400 and 800 F., a pressure between 50 and 2000 p.s.i.g., and a liquid hourly space velocity for the combined raffinate and other paraflinic feedstock through the averaging catalyst of .5 to 5.0.

References Cited UNITED STATES PATENTS 3,445,541 5/1969 Heckelsberg et al. 260683 3,446,868 5/1969 Box 260-676 3,294,858 12/ 1966 Butler et a1 260-683 3,484,499 12/ 1969 Lester et a1. 260-673 DELBERT E. GANTZ, Primary Examiner I. M. NELSON, Assistant Examiner US. Cl. X.R. 260-683 D UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,78 ,622 Dated Januarv 8 197 4 Inventor) Thomas R. Hughes It is certified that error appears in the aboe-1dentified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, llne 21, "86 5871, now U.S. Patent 3,593, 62 should read 864+,87l now abandoned Col. 2, line 46;, "am" should read --are--. Col. 5, line 1, "averging" should read --averaging-.

Col 5., line 3; "examplee" should read --example-- Signed and sealed this 6th day of August 1974.

' (SEAL) Attest: v I MCCOY M. GIBSON, JR. (3. MARSHALL DANN =-Attesting Office-T Commissioner of Patents