MXPA97008164A - Na improvement process - Google Patents

Abstract

The present invention relates to the production of a petrol with a low sulfur content, of a relatively high octane number, from a naphtha containing thermally fractionated sulfur, such as naphtha of the coker, by hydrodesulfurization followed by the treatment on an acid catalyst, perfectly a zeolite such as ZSM-5 or the beta zeolite with a hydrogenation component, preferably molybdenum. The treatment on the catalyst acid in the second step restores the octane loss which is carried out as a result of the hydrogenase treatment and leads to a gasoline product with a low sulfur content

Description

NAFTA IMPROVEMENT PROCESS Field of the Invention The present invention relates to a process for the concentration or enrichment of hydrocarbon streams. It relates more particularly to a process for improving or enriching fractions of petroleum from the boiling range of naphtha containing substantial proportions of sulfur impurities.

Background of the Invention Heavy fractions of petroleum, such as vacuum gas oil, or even waste such as atmospheric waste, can be catalytically thermocracked to lighter and more valuable products, especially gasoline. The catalytically thermocracked gasoline forms a major part of the group of gasoline products in the United States of America. It is conventional to recover the product from the catalytic thermofraction and to fractionate the thermo-fractionation products into various fractions such as light gases; naphtha, including light and heavy Rßf.025957 gasoline; Distillate fractions, such as heating oil and diesel fuel; fractions based on lubricating oil; and heavier fractions. Where the fraction of the oil that is catalytically thermofractioned contains sulfur, the products of the catalytic thermofraction usually contain sulfur impurities which normally require removal, usually by hydrotreating, to comply with the relevant product specifications. These specifications are expected to become stricter in the future, possibly allowing no more than about 300 ppmp (parts per million by weight) of sulfur in the gasolines for the engines. In the hydrotreating of naphtha, the naphtha is contacted with a suitable hydrotreating catalyst at elevated temperature and at a somewhat elevated pressure in the presence of a hydrogen atmosphere. A suitable family of catalysts that have been widely used for this service is a combination of a Group VIII element and a Group VI element, such as cobalt and molybdenum, on a suitable substrate, such as alumina. In the hydrotreatment of petroleum fractions, particularly naphthas, and more particularly heavy thermocracked gasoline, the molecules containing the sulfur atoms are gently thermocracked to release their sulfur, usually as hydrogen sulfide. After the hydrotreating operation is complete, the product can be hydrogenated, or even distilled instantly, to release the hydrogen sulfide and collect the gasoline now sweetened. Although this is an effective process that has been practiced on gasolines and heavier oil fractions for many years to produce satisfactory products, it has disadvantages. Naphthas, including light and full-range, unrefined naphtha, can be subjected to a catalytic reformation to increase their octane number by converting at least a portion of the paraffins and the cycloparaffins in them to aromatics. The fractions that are to be fed to the catalytic reforming, such as on a platinum type catalyst, also need to be desulfurized before reformation because the reforming catalysts are generally not sulfur tolerant. Accordingly, naphthas are usually pretreated by hydrotreating to reduce their sulfur content prior to reformation. The value or evaluation of the octanes of the reformed compounds can be further increased by processes such as those described in U.S. Pat. Nos. 3,767,568 and U.S. 3,729,409 (Chen) in which the octane value of the reformed compound is increased by the treatment of the compound reformed with ZSM-5. Aromatic compounds are generally the source of a high octane number, particularly very high search octane numbers and therefore are desirable components of the group or set of gasolines. They, however, have been subject to severe limitations as a component of gasoline because of possible adverse effects on the ecology, particularly with reference to benzene. It has therefore become desirable, whenever feasible, to create a group or group of gasolines in which the higher octanes are contributed by the olefinic and branched chain paraffinic components, rather than the aromatic components. Naphthas of the light and complete range or range can contribute a substantial volume to the group or group of gasolines, but they do not contribute significantly to the higher octane values without reformation. In U.S. Patents Nos. 5,346,609 and (Serial No. 08 / 850,106) the assignees of the present invention have described a process for effectively desulfurizing the catalytically thermocracked naphthas while maintaining a high octane number. Briefly, the process comprises an initial hydrodesulfurization step which reduces the sulfur to an acceptable level, albeit at the expense of the octane which is restored or recovered in a subsequent step by treatment on an acid catalyst such as one based on the ZSM- 5, as described in the US patents Nos. 5,346,609 and 5,409,596, the zeolite beta as described in U.S. Pat. No. 5,413,696 or MCM-22 as described in U.S. Pat. No. 5,352,354. The use of a ZSM-5 catalyst containing molybdenum is described in International Patent PCT / US95 / 10364 and a zeolite beta catalyst containing molybdenum in U.S. Pat. No. 5,411,658. Other highly unsaturated fractions boiling in the boiling range of gasoline, which are produced in some refineries or petrochemical plants, include gasoline obtained by pyrolysis and coker naphtha. Coke naphtha is a fraction which is produced by a coking process, either a delayed coke, a fluid coke or a contact coke, all of which are well known processes in the oil refining industry. See, for example, Modern Petroleum Technology, Hobson and Pohl (Ed.), Applied Science Publ. Ltd., 1973, ISBN 085334 487 6, pages 283-288, and Advances in Petroleum Chemistry and Refining, Kobe and McKetta, Interscience, N.Y. 1959, Vol. II, pages 357-433, to which reference is made for a description of these processes. The coker naphtha, which is produced by the coking of the waste raw materials, has a high sulfur content, typically at least 1,000 ppmp (0.1 weight percent) or even higher, for example 5,000 to 10,000 ppmp (0.5 to 1.0 percent) and a low number of octanes, typically not higher than about 70. It is also unstable and tends to form gums by the polymerization of diolefins and other unsaturated species which are present in these products Thermally fractioned Although the content of the unsaturated compounds is high, with a bromine number typically in the range of 50 to 80, there is no positive contribution to octane from the unsaturated compounds because they are components of a low octane content. The combination of a high sulfur content and a low octane content makes the coker naphtha an unlikely candidate for treatment by the process described in the patents referred to above. It has been found, however, that the use of molybdenum-containing catalysts is favorable for the treatment of coker naphthas, using either medium pore size or large pore size acid components in the catalysts, especially ZSM-5 and beta zeolite.

Detailed description of the invention According to the present invention, the process for catalytically desulfurizing thermally-fractionated fractions in the boiling range of gasoline, especially coker naphtha, makes it possible for the sulfur to be reduced to acceptable levels for the mixture in the group or group of Refinery gasolines The value of octanes can be retained or even, in favorable cases, improved. According to the present invention, a thermally fractionated naphtha containing sulfur, such as coker naphtha, is hydrotreated, in a first step, under conditions which remove at least a substantial proportion of the sulfur. The hydrotreated intermediate is then treated, in a second step, by contact with an acid-functional catalyst under conditions which convert the fraction of the hydrotreated intermediate to a fraction in the boiling range of gasoline of the highest octane value. . Figures 1 to 3 are a series of graphs of octane and yield from the coker naphtha treatment using the catalysts of ZSM-5 and zeolite beta, as described in the Examples.

Feeding The feed for the process comprises a fraction of thermally fractionated oil that • contains sulfur, which boils in the boiling range of gasoline. The preferred feed of this type is coker naphtha although other thermally fractionated feeds such as gasoline obtained by pyrolysis can also be used. Coke naphtha is obtained by thermal fractionation of a residual feed in a coker. As mentioned above, coking processes are well established in the oil refining industry and are used to convert the raw materials of the cargo, residual, into liquid products of higher value. The delayed coking process is in wide use in the United States of America as noted above; variants of typical delayed coking processes are described in U.S. Pat. Nos. 5,200,061; 5,258,115; 4,853,106; 4,661,241 and 4,404,092. The naphthas of the coker can be light naphthas which typically have a boiling range of about C? at 165.55 ° C (330 ° F), the naphtha of the entire range typically has a boiling range of about Cs up to 215.55 ° C (420 ° F), the heavier naphtha fractions boiling in the range of about 126.66 ° C (260 ° F) to 211.11 ° C (412 ° F), or heavy gasoline fractions that boil at, or at least within, the range of approximately 165.55 ° C (330 ° F) to 260 ° C (500 ° F) ), preferably approximately 165.55 ° C (330 ° F) to 211.11 ° C (412 ° F), depending on the mode of operation of the coker fractionator (combined tower) and the requirements of the refinery. The present process can be operated with the complete naphtha fraction obtained from the coker or, alternatively, with part of it. The sulfur content of the coker naphtha will depend on the sulfur content of the feed with respect to the coker as well as the boiling range of the selected fraction used as the feed in the process. The lighter fractions, for example, will tend to have lower sulfur contents than the higher boiling fractions. As a practical rule, the sulfur content will normally exceed 1,000 ppmp and will usually be in excess of 2000 ppmp and in most cases in excess of approximately 5000 ppmp. The nitrogen content is not as characteristic of the feed as the sulfur content and is preferably not greater than about 50 ppmp although higher nitrogen levels typically of up to about 150 ppmp can be found in certain naphthas. As described above, coker naphthas are fractions containing significant amounts of diolefins as a result of thermal fractionation.

Process Configuration The process is carried out in the manner described in U.S. Pat. No. 5,346,609, as to what are the operating conditions and the type of catalyst that can be used, such reference is made for details as to them. Briefly, the naphtha feed is treated in two steps by hydrotreating the feed first by the effective contact of the feed with a hydrotreating catalyst, which is suitably a conventional hydrotreating catalyst, such as a combination of a Group VI metal and of a Group VIII metal, on a suitable refractory support such as alumina, under hydrotreating conditions. Under these conditions, at least some of the sulfur is separated from the feed molecules and converted to hydrogen sulfide, to produce a hydrotreated intermediate comprising a normally liquid fraction that boils substantially in the same boiling range as the feed ( of boiling gasoline), but which has a lower sulfur content than the food. This hydrotreated intermediate which also boils in the boiling range of gasoline (and usually has a boiling range which is not substantially higher than the boiling range of the feed), is then treated by contact with a catalyst. acid under conditions which produce a second product comprising a fraction which boils in the boiling range of gasoline, which has an octane number higher than the portion of the hydrotreated intermediate product fed to this second step. The product of this second step usually has a boiling range which is not substantially higher than the boiling range of the feed with respect to the hydrotreating device, but is of a lower sulfur content while having an octane rating at the same time comparable or even higher than the result of the treatment of the second stage. The catalyst used in the second stage of the process has a significant degree of acid activity, and for this purpose the most preferred materials are the crystalline refractory solids having an effective intermediate pore size and the topology of a zeolitic material, which , in the form of the aluminosilicate, has a restriction or conditioning index of about 2 to 12. A metallic component having a slight degree of hydrogenation activity is preferably used in this catalyst.

Hydrotreating The temperature of the hydrotreating step is suitably from about 260 to 454 ° C (about 500 to 850 ° F), preferably about 260 to 400 ° C (500 to 750 ° F) with the exact selection depending on the desired desulphurization. for a given feed and catalyst. Because the hydrogenation reactions which are carried out in this step are exothermic, an elevation in temperature is carried out throughout the reactor; this is really favorable for the total process when it is operated in cascade mode because the second step is one that involves fractionation, an endothermic reaction. In this case, therefore, the conditions in the first step must be adjusted not only to obtain the desired degree of desulfurization of the coker's naphtha feed but also to produce the required inlet temperature for the second step of the process, to promote • selective thermofraction reactions, of the desired shape, in this step. A temperature rise of approximately 11 to 111 ° C (approximately 20 to 200 ° F) is typical under most hydrotreating conditions and with reactor inlet temperatures in the range of 260 to 427 ° C (500 to 800 ° C). F), normally, an initial temperature required for the cascade operation will be provided with respect to the second step of the reaction. Since the feeds are actually desulfurized, low to moderate pressures may be used, typically from about 445 to 10443 kPa (about 50 to 1500 pounds per square inch gauge), preferably in the approximate form of 2170 to 7,000 kPa (about 300 to 1000 pounds per square inch). square inch gauge). The pressures are the total pressure of the system, at the entrance of the reactor. The pressure will normally be chosen to maintain the desired aging rate for the catalyst during use. The space velocity (hydrodesulfurization step) is typically in the form of approximately 0.5 to 10 LHSV (h "1), preferably in the form of approximately 1 to 6 LHSV (h_1) .The ratio of hydrogen to hydrocarbon in the feed is typically in approximately 90 to 900 n.1.1"1 (approximately 500 to 5000 standard cubic feet / barrel), usually in the approximate form of 180 to 445 n.1.1" 1 (approximately 1000 to 3000 standard cubic feet / barrel). The desulfurization will depend on the sulfur content of the feed and, of course, on the sulfur specification of the product with the reaction parameters selected according to this, it is not necessary to reach very low nitrogen levels, but the levels of Low nitrogen can improve catalyst activity in the second step of the process Normally, denitrogenation which accompanies desulphurisation will lead to an acceptable organic nitrogen content in the feed with respect to the second step of the process; if necessary, however, to increase the denitrogenation to obtain a desired level of activity in the second step, the operating conditions in the first step can be adjusted accordingly. The catalyst used in the hydrodesulfurization step is suitably a conventional desulfurization catalyst composed of a metal of the Group VI and a Group VIII metal on a suitable substrate, as described in U.S. Pat. Do not. ,346,609. The metal of Group VI is preferably molybdenum or tungsten and the metal of Group VIII is usually nickel or cobalt.

Octane Restoration - Second Processing Step After the hydrotreating step, the hydrotreated intermediate is passed to the second step of the process in which the thermofraction is carried out in the presence of the acid working catalyst. The effluent of the hydrotreating step can be subjected to a separation of the interetap step to remove the inorganic sulfur and nitrogen such as hydrogen sulfide and ammonia as well as the light endings but this is not necessary and, in fact, it has been found preferable to work cascading the product from the first stage directly to the second step to use the hydrotreatment exotherm to supply the enthalpy for the second stage of the treatment. The second step of the process is characterized by a controlled degree of selective thermofraction in terms of the shape of the hydrotreated, desulfurized effluent of the first step, to provide the desired contribution to the octane value of the product. The reactions carried out during the second step are mainly the selective thermofractionation in terms of the shape of the paraffins with a low octane content, to form products with a higher content of octanes, both by the selective thermofraction of heavy paraffins to lighter paraffins such as thermo-fractionation of n-paraffins with a low octane content, in both cases with the generation of olefins. Some isomerization of n-paraffins to branched chain paraffins of a higher octane content can be carried out, making an additional contribution to the octanes of the final product. The mechanism for the improvement of octanes with Mo / ZSM-5 and Mo / beta also seems to include the dehydrocyclization / aromatization of paraffins to alkylbenzenes. The conversion with recovery of organic materials (particularly with Mo / beta) also improves the octane content. In favorable cases, the evaluation of the original octane of the feed may be restored completely or perhaps even exceeded. Since the volume of the second stage product will typically be comparable to or even exceed that of the original feed, the number of octane barrels (octane x volume evaluation) of the final desulfurized product may exceed the octane barrels of the product. feeding. The conditions used in the second step are those in which it is appropriate to produce this controlled degree of thermocracking. Typically, the temperature of the second step will be from about 260 to 455 ° C (about 500 to 850 ° F), preferably about 315 to 425 ° C (about 600 to 800 ° F). The pressure in the second reaction zone is not critical since no hydrogenation is desired at this point in the sequence although a lower pressure in this stage will tend to favor the production of olefin with a consequent favorable effect on the octane of the product. The pressure will therefore depend primarily on operational convenience and will typically be comparable to that used in the first stage, particularly if a cascade operation is used. Accordingly, the pressure will typically be about 445 to 10445 kPa (about 50 to 1500 pounds per square inch gauge), preferably about .2170 to 7000 kPa (about 300 to 1000 pounds per square inch gauge), with speeds comparable spatially, typically from about 0.5 to 10 LHSV (h "1), typically in the approximate form 1 to 6 LHSV (h_1) .The hydrogen to hydrocarbon ratios typically range from about 0 to 890 n.1.1" 1 (0 to 5000 standard cubic feet / barrel), preferably in approximate form 18 to 445 n.1.1"1 (approximately 100 to 3000 standard cubic feet / barrel) will be selected to minimize the aging of the catalyst.The use of relatively lower hydrogen pressures thermodynamically favor the increase in volume which occurs in the second step and for this reason, the lower total pressures are preferred if they can be accommodated by the aging restrictions of the two catalysts In the cascade mode, the pressure in the second step may be restricted by the requirements of the first but in the two-stage mode the possibility of recompression allows the pressure requirements to be selected individually, producing the potential to optimize the conditions at each stage, consistent with the objective of restoring octane loss while retaining the volume of the final product, the conversion to products that boil down of the boiling range of gasoline (C5-) during the second stage is kept to a minimum but with the thermally fractionated naphtha feeds, a relatively high temperature may be required to give the desired octane increase of the product. The catalyst used in the second step of the process possesses sufficient acidic functionality to cause the desired thermofraction reactions to restore the octane loss in the hydrotreating step. The preferred catalysts for this purpose are the catalytic materials of intermediate pore size zeolitic behavior which are exemplified by those acidic operating or operating materials having the topology of the intermediate pore size aluminosilicate zeolites. These zeolitic catalytic materials are exemplified by those which, in their aluminosilicate form, could have a Restriction Index between about 2 and 12, such as ZSM-5, ZSM-11, ZSM-12, ZSM-21, ZSM-22. , ZSM-23, ZSM-35, ZSM-48, ZSM-50 or MCM-22, as described in US Pat. No. 5,346,609. However, other catalytic materials having the appropriate acid functionality may be employed. A particular class of catalytic materials which can be used are, for example, zeolite materials of large pore size which have a Restriction index of up to about 2 (in the form of the aluminosilicate). Zeolites of this type include mordenite, beta zeolite, faujasites such as zeolite Y and ZSM-4, with beta zeolite which is preferred for the treatment of coker naphthas. It is desirable to include a hydrogenation component in this catalyst, as described in the document Serial No. 08 / 133,403, which is referred to for details of acid catalysts containing molybdenum. Molybdenum is the preferred hydrogenation component, which produces good results with both ZSM-5 and beta zeolite, as shown in the following Examples. With coke naphtha, the Mo / ZSM-5 exhibits good activity for octane recovery. The octane value of the product can be increased to a value as high as 75 of the course or vehicle, raising the temperature of the reactor. However, the loss of yield per octane is very high. The Mo / beta has a lower activity for octane recovery than the Mo / ZSM-5 but has a significant advantage in the higher gasoline yield.

Examples The following examples illustrate the operation of the present process. In these examples, the parts and percentages are by weight unless they are expressly stated to depend on some other basis. Temperatures are in ° C and pressures in kg / cm2 man., Unless it is expressly stated that they will depend on some other base.

Example 1 Preparation of a Mo / ZSM-5 Catalyst A physical mixture of 80 parts of ZSM-5 and 20 parts of pseudoboehmite alumina powder (by weight, 100% solids base) was milled to form a uniform mixture and formed into 1.6 mm cylindrical extruded materials (1 / 16 inch) using a standard auger or screw extruder. The extruded materials were dried on a band dryer at 127 ° C and then calcined at 480 ° C in a nitrogen atmosphere for 3 hours followed by a 6 hour air calcination at 538 ° C. The catalyst is sprayed with 100% steam at 480 ° C for about 4 hours.

The extruded materials subjected to the steam are impregnated with 4% by weight of Mo and 2% by weight of P using an incipient damp method with a solution of hepta ammonium olibdate and phosphoric acid. The impregnated extruded materials were then dried at 120 ° C overnight and calcined at 500 ° C for 3 hours. The properties of the final catalyst are listed in Table 1 below.

Example 2 Preparation of the catalyst of Mo / zeolite beta A physical mixture of 65 parts of zeolite beta and 35 parts of powder of pseudoboehmite alumina (parts by weight, base of 100% solids) is combined to form a uniform mixture and formed into extruded materials of cylindrical shape of 1.6 mm (1 / 16 inch) using a standard screw extruder or auger. The extruded materials were dried on a band dryer at 127 ° C and then calcined with nitrogen at 480 ° C for 3 hours followed by a 6 hour air calcination at 538 ° C. The catalyst was then subjected to steam action at 100% steam at 480 ° C for 4 hours.

The extruded materials were impregnated with 4% by weight of Mo and 2% by weight of P using an incipient damp method with ammonium heptamolybdate and a phosphoric acid solution. The impregnated extruded materials were then dried at 120 ° C overnight and calcined at 500 ° C for 3 hours. The properties of the final catalyst are listed in Table 1. The properties of the hydrotreating catalyst are also reported in Table 1 given below.

Table 1 Physical Properties of the Catalysts Ca. G? T. Gat. Mo / Bßta Zeolite ISM-5 Bßta Zeolite, par cent weight 80 65 Alpha 132 * 141 Surface Area, p g-l 260 289 415 Sardine of n-ffexano,% weight 10.4 - Scxta? N of ci-He-earo,% weight 14.9 Co, weight percent 3.4 NA NA M? , P01- hundred weight 10.2 3.6 3.8 p par cent weight -. 1.7 1.7 * Before the -u-p-egnac-Lcn of Mo NA MD api ipahle Example 3 Improvement or enrichment of coker Naphtha with Mo / ZSM-5 catalyst This example illustrates the operation of the improvement or enrichment of the coker naphtha of a Mo / ZSM-5 catalyst (Example 1) to produce a gasoline of low sulfur content. The properties of the raw materials (Cocaine Naphtha I) are shown in Table 2 given below, along with those of other coker naphthas used in Example 4.

Table 2 Properties of Cocaine Naphtha Feeding tfefta 1 del (-bq-ñzat- -r Nafta 2 del (TprjTiyarfar General Properties Intercalo aml licicn Nominal, ° C 76.66 - 165.55 87.22 - 204.44 Dens-u-fe BeLatiMß, g / sc 0.742 0.772 Total sulfur,% weight 0. 7 0. 6 Nitrogen, ffp- 71 120 Nu-exD of Ba-mo 72. 0 61.9 Octane of the Search or Ipvestigacix-n 68.0 60.0 Octane of the Msbar 60. 6 56. 3 Distillation, ßC (D28887) IBP ZL.ll 76.11 5% 36.66 95.55 10% 58.88 100.55 30% 96.11 128.88 50% 123.33 152.77 70% 147.22 173.33 90% 171.66 198.88 95% 177.22 204.44 EP 211.66 227.22 The experiments were carried out in a fixed bed pilot unit using a commercial CoMo / A1203 hydrodesulfurization catalyst (HDS) and the Mo catalyst. / ZSM-5. Each catalyst was sized to a 14/28 mesh from the U.S. and it was charged in a reactor. The pilot unit is operated in a cascade mode where the desulfurized effluent from the hydrotreating stage is cascaded directly to the catalyst containing zeolite without the removal of the ammonia, hydrogen sulfide, and light hydrocarbon gases in the interetapa. The conditions used for the experiments included temperatures from 260 ° C-427 ° C (500-800 ° F), 1.0 LHSV (based on fresh feed relative to the total catalysts), 535 n.1.1"1 (3000 ft. standard cubic / barrel) of hydrogen circulation without recycling, and an inlet pressure of 4240 kPa abs (600 pounds per square inch gauge) The ratio of the hydrotreating catalyst to the thermal cracking catalyst was 1/1 vol / Table 3 summarizes the results: Octane recovery and gasoline volume performance are plotted in Figures 1 and 2 as a function of temperature.

Table 3 Cocaine Naphtha Improvement with Mo / ZSM-5 LIKE HDS / Alipeptacicn of Nafta M? / ZSM-5 Ttepp., Stage 1, ° C m 373.88 371.66 372.22 Tfnp., Stage 2, ° C 367.22 400.55 414.44 Das sotze la Garriente 5.0 8.2 9.2 Amlisris of the Product Sulfur,% by weight 0.7 0.020 * 0.006 * 0.012 * Nitrogen, pppp 71 < 1 * < 1 * 7 * Octane C5 + - Search 68.0 45.4 68.3 77.5 Octane C5-- Kill 60.6 46.8 66.3 74.7 Rarii? Olefin protein,% weight C2- + C3- + C4- 0.2 1.4 1.2 C5- + 39.9 0.2 0.6 0.4 Ren-ün? Ents C5 + Gasoline% vol. 100 100.3 79.3 68.8% weight 100 98.8 78.1 68.4 e-ndip of the Proaeso,% weight C1 + C2 0.1 1.1 2.2 C3 0.4 9.0 13.8 04 1.0 12.4 16.4 C5-300 * F 71.3 71.4 61.7 52.0 300T + 28.7 27.4 16.4 16.4 Conversion,% 300 * F + - 11 • 47 47 Equilibrium Censure (m l) 0.0712 0.1068 0.1424 *: Measured with a separate product to remove H2S. Conditions: 4240 kPa abs., 535 n.1.1"1 of H2, 1.0 of total LHSV The data contained in Table 3 and Figure 1 clearly demonstrate the improvement of the quality of the naphtha product of the coker with this process. of catalyst of HDS and Mo / ZSM-5 produces a gasoline with a very low sulfur content (<200 ppm) and nitrogen (<10 ppm). After hydrodesulphurisation, the octane value of coker naphtha decreases up to about 45 octane road or vehicle.With Mo / ZSM-5, the octane of the feed is easily recovered at about a reactor temperature of 398.88 ° C (750 ° F). / ZSM-5 can further increase the octane level of the coker naphtha.The desulphurised gasoline can be produced with an octane for the road or vehicle from 77 to a gasoline yield of approximately 68% .The produced gasoline contains a very high level. low olefin s (< 1%); This is an advantage to meet olefin specifications for clean fuels.

Example 4 Cocaine Naphtha Improvement with Mo / ZSM-5 This example illustrates the operation of improving the coker naphtha of a Mo / ZSM-5 catalyst (Example 1) with another naphtha feed from the coker. The properties of the raw materials (Cocaine Naphtha II) are shown in Table 2 above. The experiments were carried out under conditions similar to those of Example 3 with the exception of a lower hydrogen circulation (2000 standard cubic feet / barrel) and a slightly lower total pressure (37.65 kg / cm2 man. (535 pounds per inch). square gauge)). Table 4 summarizes the results. Octane recovery is plotted in Figure 3 as a • function of temperature.

Table 4 Cocaine Naphtha Improvement with Mo / ZSM-5 • LIKE HDS / Al-iiBBntrKn.cn of Nafta MO / ZSM-5 Tepp. Stage 1, ° C - 328.88 372.22 370.55 371.11 Iteprp., Stage 2, ° C 148.88 371.11 388.33 405.0 Days in the stream 181.3 168.2 176.8 173.3 Product Analysis Sulfur,% by weight 0.6 < 0.002 * 0.006 * 0. 002 * 0. 014 * Nitrogen, f q 120 5 * < 5 * < 5 * < 5 * Octane search + C5 60.0 37.1 51.9 62.7 73.1 Octane Engine + C5 56.3 31.2 55.9 62.9 70.5 Rentuipiepto of Olefira,% weight C2- + C3- + C4 »0.0 0.6 1.0 0.8 05- 34 ** 0.1 0.6 0.6 0.4 epidimiapto Giasolin + C5% vol. 100 101.1 93.2 85.6 75.4% weight 100 99.7 93.0 84.3 74.6 Piuuts Renduites -?% Weight C1 + C2 0.1 0.3 0.7 1.7 03 0.1 2.9 6.2 11.4 04 0.4 4.0 9.3 13.1 C5-300OF 53.2 50.0 53.8 51.2 45.1 300OF + 46.8 49.7 39.2 33.1 29.5 Conversion,% 300OF + - 7 26 38 45 Cbnst-mD de ftu ± rogato (mVl) 0.0712 0.0712 0.0979 0.1115 *: Measured with the separate product to remove H2S **: Estimated bromine number Conditions: 37.65 kg / cm2, 2000 standard cubic feet / H2 barrel, 1.0 total LHSV.

The data contained in Table 4 and Figure 3 also demonstrate the improvement of the coke naphtha quality product with this process. Again, the gasoline produced has a very low sulfur content (<150 ppm), nitrogen (<5 ppm), and olefins (<1% weight). After hydrodesulfurization, the octane of the coker's naphtha decreases to 34 octane of the vehicle or vehicle. The octane of the feed can be recovered with the Mo / ZSM-5 at temperatures slightly above 371.11 ° C (700 ° F); the gasoline yield in these conditions is around 90% in vol. of C5 +. By increasing the reactor temperatures, the octane of the desulfurized gasoline can be increased by almost 40 octane numbers of the track or vehicle up to 72 octanes of the track or path with a yield of 75% vol. of gasoline.

Example 5 Improvement of Cocaine Naphtha with Mo / Beta This example illustrates the operation of improving the coker naphtha of a Mo / beta catalyst (Example 2) to produce a gasoline with a low sulfur content. The same coker naphtha used in Example 3 (Cocaine Naphtha I) was used for these experiments. Table 5 summarizes the results. Octane recovery and gasoline volume performance are plotted in Figures 1 and 2 as a function of temperature.

Table 5 Improvement of Cocaine Naphtha with Mo / Beta , LIKE HDS / Al-bieptac-Lcn from Naphtha M O / Bet "teip.ra-apt 1, ° C - 343.88 372.22 375 374.44 Tfcarp. Stage 2, ° C "341.66 370.0 400.5 413.33 nías on the Cb-criepte" 27.4 28.4 29.4 31.4 Product Analysis Sulfur,% by weight 0.7 o.oc > 5 * 0.005 * 0.019 * 0.009 Ntl-cuijE-po, jjjn 71 1 * 1 * 2 * < 1* Octane of Search + C5 + 68.0 50. 7 52.8 59.6 59.2 Cctanodel M - tar + C5 60.6 51.9 54.4 59.3 59.7 Olefin yield,% weight C2- + C3- + C4- 0.2 0.6 0.6 0.6 C5- + 39.9 0.1 0.3 0.3 0.3 R-? Rriip? Eptos (-5+ Gfe-solina% vol.100 97.7 94.4 92.9 93.4% weight 100 96.6 93.1 92.7 92.4 er - h? ratar-tt > del Pruoeso,% ¿to C1 + C2 0.1 0.2 0.2 0.2 03 0.6 1.3 1.3 1.4 04 2.9 5.6 5.7 6.1 05-300'F 71.3 71.4 71.3 69.7 71.9 300 * F + 28.7 25.2 21.8 23.0 20.5 Conversion,% 300 * F + - 19 30 26 34 Censuro fe lü? L -? Yt-nu (m3?) _ 0.0712 0.089 0.0534 0.071-i *: Measured with the separated product to remove the H2S Conditions: 4240 kPa abs., 535 n.1.1"1 H2, 1.0 LHSV total.

The data contained in Table 5 demonstrate that the combination of Mo / beta catalyst and HDS also produces gasoline with a very low sulfur content (<200 ppm) and nitrogen (<10 ppm). After hydrodesulfurization, the octane value of the coker naphtha decreases to approximately 45 octanes of the pathway or vehicle. With the Mo / beta, it is possible to recover the octane value up to approximately 60 octanes of the pathway or vehicle (Table 5, Figure 1). Unlike the Mo / ZSM-5, the Mo / beta shows an elevated activity at low temperatures and at high temperatures the recovery of the octane value is rather insensitive to changes in temperature. The Mo / beta has an advantage in the higher gas volume performance compared to the Mo / ZSM-5 (Figure 2). The total number of octane-barrels is higher with the Mo / beta catalyst.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following 15 20 25

Claims (10)

1. A process for improving a fraction of naphtha feed of the coker, unsaturated, thermally fractionated, containing sulfur, which boils in the boiling range of gasoline, characterized in that it comprises: submitting a residual feed in a coker to form a fraction of the naphtha feed of the sulfur-containing coker, which boils in the boiling range of gasoline and contains at least 1000 pph sulfur, contact the sulfur-containing feed fraction with a hydrodesulfurization catalyst in a first zone reaction, operating under a combination of elevated temperature, high pressure and an atmosphere comprising hydrogen at a temperature of about 260qC to 427 ° C (500-800 ° F), a pressure of about 445 to 10445 kPa (50-1500 pounds) per square inch gauge), a space velocity of approximately 0.5 to 10 LHSV, and a hydrogen ratio ah idrocarburium of approximately 90 to 900 n.1.1"1 (500 to 5000 standard cubic feet of hydrogen per barrel) of feed, to produce an intermediate product comprising a normally liquid fraction which has a reduced sulfur content and a reduced amount of octane when compared to food; contacting at least the portion of the boiling range of the intermediate product gasoline in a second reaction zone with an acid functional catalyst which also includes molybdenum as a metal component having a hydrogenation functionality at a temperature of about 315 at 455 ° C (600 to 850 ° F), a pressure of about 445 to 10445 kPa (50 to 1500 pounds per square inch gauge), a space velocity of about 0.5 to 10 LHSV, and a hydrogen to hydrocarbon ratio of about 0 to 890 n.1.1"1 (0 to 5000 standard cubic feet) of hydrogen per barrel of feed to convert the portion of the boiling range of gasoline to a product that comprises a fraction boiling in the boiling range of gasoline , which has an octane number higher than the fraction of the boiling range of the intermediate product gasoline.

2. The process according to claim 1, characterized in that the feed fraction comprises a naphtha of the coker having a boiling range within the range of Ce at 215.55 ° C (420 ° F).

3. The process according to claim 1 or 2, characterized in that the fraction of the feed comprises a naphtha fraction of the coker with a boiling range in the range of c5 to 165.55 ° C (330 ° F).

4. The process according to any of claims 1 to 3, characterized in that the acid catalyst comprises a zeolite of intermediate pore size.

5. The process according to claim 4, characterized in that the zeolite of intermediate pore size has the topology of the ZSM-5.

6. The process according to claim 5, characterized in that the zeolite of the intermediate pore size is in the form of the aluminosilicate.

7. The process according to any of claims 1 to 6, characterized in that the acid catalyst comprises the zeolite beta in the form of the aluminosilicate.

8. The process according to any of claims 1 to 7, characterized in that the second stage of the improvement is carried out at a temperature of about 343.33 to 425 ° C (650 to 800 ° F), a pressure of about 2170 to 7,000 kPa (300 to 1000 pounds per square inch gauge), a space velocity of approximately 1 to 3 LHSV, and a hydrogen to hydrocarbon ratio of approximately 18 to 445 n.1.1"1 (100 to 3000 standard cubic feet) of hydrogen per barrel of food.

9. The process according to any of claims 1 to 8, characterized in that the coker naphtha is produced by the delayed coking of a residual petroleum fraction.

10. The process according to any of claims 1 to 9, characterized in that the coker naphtha has a sulfur content of 1,000 to 10,000 ppm and a bromine number of 30 to 100.