FI86632B - Catalytic composition for isomerization of paraffin hydrocarbons - Google Patents

Description

1 86632

Catalytic composition for the isomerization of paraffinic hydrocarbons

The present invention relates to an improved catalytic composition and a hydroisomerization process using that catalytic composition. More particularly, this invention relates to an isomerization catalyst composition comprising a hydrogenation function selected from Group VIII metals, a hydrogenated crystalline aluminosilicate zeolite, and a refractory (difficult to reduce) inorganic oxide. The new catalytic composition is particularly useful for the isomerization of isomerizable hydrocarbons containing sulfur as an impurity.

The isomerization of low molecular weight normal paraffins is well known in the art. This reaction is of considerable importance in the oil industry, due to the substantially higher octane numbers of isoparaffins compared to their normal forms. Because gasoline blends require a distribution of substances with different boiling points, isoparaffins are important blend components in the C 1 -C 6 range. Until now, it has been the practice to isomerize paraffins to equilibrium mixtures of their branched isomers with various catalysts. Friedel-Crafts catalysts, such as aluminum chloride, are known to be effective isomerization catalysts. Precious metals such as platinum on the surface of halogenated alumina or silica alumina have also been used effectively in the isomerization of hydrocarbons. Recently, crystalline aluminosilicate zeolites that have been shown to be catalytically active have been used effectively in the isomerization of hydrocarbons. Both natural and synthetic crystalline aluminosilicates have been used. These include X-type and Y-type zeolites as well as synthetic mordenite.

Zeolites in particular, known as mordenites, have received much attention. Mordenites are crystalline, natural or synthetic aluminosilicate-type zeolites: they generally comprise a composition expressed as moles of the following oxide 2 86632 1.0 + 0.2 Na 2 O · Al 2 O 3 · 10 + 0.5 SiO 2;

The amount of SiO 2 may also be higher. Substituting all or part of the sodium, other alkali metals and / or alkaline earth metals may be present.

In general, it has been found that the sodium form of mordenite is not particularly effective in isomerizing hydrocarbons, and that replacing all or most of the sodium cations with hydrogen ions provides a more preferred hydrogen form of mordenite. The conversion of the sodium form to the hydrogen form can be accomplished in many ways.

One method is the direct replacement of sodium ions with hydrogen ions, using an acidified aqueous solution using the ion exchange method. Another method involves the substitution of sodium ions with ammonium ions followed by the decomposition of the ammonium solution using oxidative treatment at high temperature.

The activity and selectivity of the hydroisomerization catalysts depend on various factors, such as the method of preparation of the catalyst, the presence or absence of promoters, the quality of the feedstocks, the quality of the feedstocks to be fed, the process conditions or the like. Suitable catalysts can be conventionally prepared by combining commercially available crystalline zeolites, such as hydrogen mordenite, with a suitable matrix material, followed by the addition of a Group VIII metal, followed by activation by conventional means. A new catalyst has been invented which has a much more advanced isomerization capacity compared to conventionally prepared catalysts.

The isomerization process of hydrocarbons containing large amounts of sulfur can now be efficiently carried out by utilizing the novel catalyst of the present invention. As exemplified in the present invention, this catalyst exhibits an isomerization ability that is excellent compared to conventional isomerization catalysts when processing feedstocks containing sulfur.

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Accordingly, a sulfur-containing catalytic composition for isomerizing isomerizable hydrocarbons is provided. This catalytic composition comprises a combination of a platinum group component with a support material containing hydrogen aluminosilicate and refractory inorganic oxide, with the essential property that the surface area 2 of the composition is at least 580 m / g. Platinum is the preferred platinum group metal, and is preferably present in an amount of 0.15 to 0.5% by weight of said composition. The preferred hydrogen aluminosilicate has a silica to alumina ratio of at least 16 and is present in an amount of 75 to 95% by weight of said composition, and most preferably has a mordenite structure. The preferred refractory inorganic oxide is alumina selected from the group consisting of gamma alumina, eta alumina, and mixtures thereof.

In another embodiment, the invention includes a process for preparing the aforementioned catalytic composition and a hydroisomerization process using that catalytic composition. The preparation of the catalyst comprises forming a composition of matter comprising hydrogen mordenite and refractory oxide, and then contacting the formed composition with an acidic aqueous solution containing ammonium ions, followed by combining the platinum group metal with the formed mixture of materials.

Preferred isomerization process conditions using this catalytic composition include a temperature range of 93 to 427 ° C, a pressure of 690 to 6895 kPa, a gauge pressure, and an hourly rate of liquid passing through the catalyst in the range of 0.25 to 5 h. The amount of hydrogen required is also in the range of 0.5 to 5 moles of H2 / mole of hydrocarbon fed.

These, as well as other embodiments of the present invention, will become apparent from the following more detailed description.

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A large number of catalyst reformations for isomerization of hydrocarbons are known in the art. It is well known that acids such as strong mineral acids can be used to modify crystalline aluminosilicate powders through cation removal and aluminum removal. Ammonium compounds have also been successfully used to convert crystalline aluminosilicates from the alkali and / or alkali metal cation form to the hydrogen form.

Combinations of acid and ammonium treatments have been proposed for use in aluminosilicate powders. U.S. Patent 3,475,345 discloses a process for converting aluminosilicate zeolites, especially synthetic mordenite in sodium form, to the hydrogen form utilizing a three-step pretreatment of the zeolite powder. These pretreatment steps include 1) hot acid treatment, 2) cold acid treatment, and 3) treatment with an ammonium compound. U.S. Patent 3,442,794 also discloses a process for pretreating aluminosilicate zeolites to the hydrogen form. The preferred zeolite is again a synthetic sodium mordenite. The disclosed method is very similar to the aforementioned U.S. Patent 3,475,345, with the distinctive feature being a separate two-step pretreatment with 1) an acid compound and 2) an ammonium compound, in free form. An important feature of both references is that the treatments are performed exclusively on aluminosilicate zeolite, specifically for the purpose of modifying said zeolite before use in a catalyst formulation, and that no mention is made of the importance of the surface area of the catalytic composition. This differs from the present invention in that each treatment performed is a post-zeolite treatment to be added to the catalyst composition to be formed and, more importantly, without any obvious modification in the zeolite itself.

Acid treatment of aluminosilicate with acid has not only been effective in converting to the hydrogen form, but has also been used as a means to increase the ratio of silicic acid to alumina. The ratio of silica to alumina, about 10: 1, is typically detected with synthetic mordenite in the sodium form and does not substantially change if ammonium treatment is used to convert the mordenite to the hydrogen form. If the mordenite powder is subjected to an acid treatment, as described in U.S. Patent 3,597,155, an increase in silica relative to alumina is obtained. Acid treatment is believed to cause a decrease in the aluminum atoms of the tetrahedra in the backbone structure, thus increasing the relative proportion of silicon atoms present in the zeolite structure. The isomerization capacity increases as the ratio of silicic acid to alumina in the mordenite powder increases. As described in U.S. Patent 3,507,931, a ratio of silicic acid to alumina greater than about 20: 1 improves the isomerization of light hydrocarbons. U.S. Patent 4,018,711 also explains that the isomerization ability is improved if a pretreated mordenite powder having a silica to alumina ratio of at least 19: 1 is included in the catalytic composition. These references again specifically explain the use of acid treatment on zeolite powder alone, with the intention of increasing the ratio of silicic acid to alumina, while the present invention includes a crystalline aluminosilicate which already has a high ratio of silicic acid to alumina in the catalytic composition. Also, these references do not disclose the importance of the surface area of the catalytic composition or its relationship to the isomerization capacity.

A common feature in the above-mentioned prior art is that in all cases only crystalline aluminosilicate, in particular the synthetic sodium form of mordenite, is subjected to an acid and / or ammonium pretreatment step (s) to modify the aluminosilicate before its inclusion in the catalyst composition. Although pretreatment of mordenite, as described in the above references, increases the isomerization performance of catalytic compositions containing such pretreated mordenite, further improvements are still available.

The reference to the accompanying drawings facilitates the understanding of the present invention. The graphical representation shown in Figure 1 of the drawings illustrates that the isomerization performance is a function of the Langmuir surface area of the catalytic composition. The isomerization ability is characterized as selectivity for the desired products, namely 2,2-dimethylbutane (2.2 DMB) and isopentane (i-C 2).

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The graph in Figure 2 of the drawings illustrates the relationship between the Researc octane value (RON-O) of the C 1+ isomerization product and the average bed temperature of the catalyst in the reactor. This RON-O value is also compared in Figure 3 to the yield of the C ^ + isomerization product, measured as a percentage by volume of the liquid from the fresh volume of the feed.

While previous work has focused solely on pretreatment of the aluminosilicate component of the isomerization catalyst, it is an object of the present invention to provide a novel catalytic composition containing improved isomerization capacity due to the carefully controlled handling of the support material.

According to the present invention, there is provided a catalytic composition for isomerizing isomerizable hydrocarbons to their branched chain equivalents, a process for preparing said catalytic composition, and a process using said catalytic composition for producing high octane mixture components.

The catalyst composition of the present invention comprises a platinum group metal component, a hydrogen crystalline aluminosilicate, and a refractory inorganic oxide, said catalyst composition having a surface area of at least 580 m / g. According to the invention, it has been found that significant improvements in isomerization capacity will occur when the surface area of the catalytic composition is 580 m / g or more. Achieving such a surface area is the subject of one embodiment of the present invention and will be described in the Examples that follow.

The metal component included in the catalytic composition to provide the hydrogenation-dehydrogenation function is a Group VIII noble metal component of 86632. Precious metals of Group VIII include "platinum series" metals and "palladium series" metals, i.e. platinum, iridium, osmium, palladium, rhodium and ruthenium, commonly referred to herein as "platinum group metals". The preferred Group VIII precious metal is platinum. The Group VIII noble metal contained in the catalytic composition of the present invention is used in an amount of about 0.1 to about 5% by weight of the composition. It is particularly preferred that the metal component is at least about 0.15% by weight and not more than 0.5% by weight.

It is within the scope of the present invention that the catalytic composition also contains a catalytically effective amount of promoter metal. Examples of such promoter metals include tin, lead, germanium, cobalt, nickel, iron, tungsten, chromium, molybdenum, bismuth, indium, gallium, cadmium, zinc, uranium, copper, silver, gold, tantalum, one or more rare earth metals, and mixtures thereof.

The crystalline aluminosilicate of the present invention is a hydrogen-shaped silica alumina having either a three-dimensional or channel-opening crystal lattice structure. Three-dimensional aluminosilicates include both synthetic and naturally occurring silica aluminas, such as faujasites, which include X-type and Y-type, ultrasta-B-Y, and the like. L-type, omega-type, and mordenite are examples of crystalline aluminosilicates with a channel-opening structure.

A particular form of aluminosilicate material known as mordenite is the preferred aluminosilicate material in the catalytic composition of the present invention. Although mordenite occurs in nature, a variety of synthetic mordenites are commercially available, usually in powder form. These synthetic mordenites can be obtained in both sodium and hydrogen form and in various silica-alumina ratios. One preferred embodiment of the present invention is that the mordenite is in the form of hydrogen and that the ratio of 8,86632 silicic acid to alumina is at least 16: 1, more particularly in the range of 16: 1 to 60: 1. The pretreatment steps described in the aforementioned references are routinely and typically used in the preparation of commercially available mordenite powders that meet the requirements for a starting material in accordance with the present invention. These pretreatment steps are used to increase the ratio of silicic acid in the mordenite zeolite to alumina and to convert the sodium form to the more preferred form of hydrogen.

The hydrogen aluminosilicate is mixed with a refractory inorganic oxide and formed into a catalyst composition. The developed catalyst composition can be prepared by any method known in the art, including well-known oil droplet and extrusion methods. The hydrogen aluminosilicate may be present in an amount ranging from 50 to about 99.5% by weight, preferably from 75 to about 95% by weight, and the refractory inorganic oxide may be present in an amount ranging from 0.5 to about 50%. .

Alumina is a preferred inorganic oxide for use in the present invention. The alumina is preferably selected from the group consisting of gamma alumina, eta alumina, and mixtures thereof. Other possible reactive inorganic oxides include, for example, silica gel, silica alumina, magnesia alumina, zirconia alumina, and the like.

Surprisingly and unexpectedly, it has been found that there is a strong correlation between the isomerization capacity of the catalyst composition of the present invention and the surface area of said composition. One preferred method of achieving maximum isomerization capacity is to utilize well-formed catalyst compositions having a surface area of at least 580 m / g. The surface area referred to herein is determined using Langmuir's method for correlating the adsorption / desorption isothermal material. The Langmuir process is particularly suitable for catalytic compositions containing 9 B6632 crystalline aluminosilicates in high concentrations. The material required for the Langmuir process is typically obtained by well-known adsorption / desorption devices, preferably a nitrogen adsorption / desorption device. Any method can be used which results in a surface area of the final catalyst mixture of at least 580 m / g. Top surface area catalytic compositions can be obtained in a variety of ways, such as by using crystalline aluminosilicate powder, which inherently has a very large surface area, or by having one component of the composition having a very large surface area in large proportions relative to the other components.

2

The preferred method of achieving a surface area of at least 580 m / g is to contact the formed catalyst mixture with an aqueous acidic solution containing ammonium ions. The resulting catalyst mixture composition may be dried and / or calcined prior to contact with the aqueous solution.

The acidity of the aqueous solution is achieved by the use of an acid. Particularly suitable are strong mineral acids such as H 2 PO 4, H 2 SO 4, HNO 2 and HCl. HCl is a preferred acid for the present invention. It is, of course, possible that mixtures of different acids may also be used. The preferred source of ammonium ion to be included in the acidic aqueous solution is NH 4 Cl, but any ammonium compound that can form ammonium ions, such as NH 4 OH, NH 2 NO 2, NH 4 sulfates, NH 4 phosphates, and the like, should be suitable.

The concentrations of acid and ammonium ions in the aqueous solution are not critical and can range from 0.5 M to 0.6 M in terms of acid content and from 0.5 M to 4 M in terms of ammonium ion content. Particularly good results are obtained by using a solution containing acid and ammonium ion concentrations in the range of 2 to 5 M for acid and 1 to 3 M for ammonium ion.

A large number of methods for contacting the formed catalytic composition with an acidic aqueous solution containing ammonium ions are in sight, without any method being particularly preferred. Such contactable methods may include, for example, a stationary catalyst bed in a static solution, a stationary catalyst bed in a mixed solution, a stationary catalyst bed in a continuously flowing solution, or any means for effectively contacting the catalyst composition with an aqueous solution.

The temperature of the contact solution should be in the range of 25 ° C to about 100 ° C, preferably in the range of about 50 ° C to about 98 ° C. The time required for the contact phase depends on the concentrations, temperature and contact efficiency. The contact time should generally be at least 0.5 h, but not more than 4 h, preferably between 1 and 3 h.

As a result of contacting the formed catalytic composition with an acidic aqueous solution containing ammonium ions, an increase in the measured surface area is observed.

Surprisingly and unexpectedly, this increase in surface area 2 to 580 m / g or more is not associated with an increase in silica relative to alumina in hydrogen crystalline aluminosilicate as measured by Magic Angle Spinning NMR (MASNMR). The MASNMR technique, which is a well-known analytical method in the art, does not show a reduction in the aluminum atoms in the tetrahedral structure of the catalyst compositions of the present invention. As will be shown below, the catalysts of the present invention having a surface area of 580 m / g perform surprisingly and unexpectedly better in performing the isomerization.

The catalyst according to the invention has a special use in the isomerization of isomerizable hydrocarbons. The group of isomerizable hydrocarbons includes saturated hydrocarbons, including paraffinic hydrocarbons, and the catalyst is even more particularly suitable for the hydroisomerization of straight-chain or slightly branched-chain paraffins containing four or more carbon atoms per molecule. The isomerization reaction can be carried out over a wide range of temperatures, but is generally in the range of about 93 ° C to about 427 ° C. Room rates of about 0.25 to about 5 volumes of liquid 86632 11 per hour of said isomerizable hydrocarbons per volume of said catalyst are preferred, with the reaction zone heads preferably being in the range of about 690 kPa to about 6900 kPa. It is particularly preferred to carry out the isomerization reaction in the presence of hydrogen, preferably in the range of about 0.5 to about 5 moles per mole of hydrocarbon to be isomerized. The function of hydrogen is primarily to improve the life of the catalyst, presumably by preventing the polymerization of reaction intermediates that would otherwise polymerize and deposit on the surface of the catalytic composition. It is not necessary to use pure hydrogen, as hydrogen-containing gases, for example hydrogen-rich gas from the catalytic rearrangement of naphthas, are suitable.

The process of this invention is more particularly suitable for isomerizable hydrocarbons, including acyclic paraffins and cyclic naphthenes. It is useful for straight-chain or partially branched-chain paraffins, such as normal butane, normal pentane, normal hexane, normal heptane, normal octane, 2-methylpentane, 3-methylpentane, 3-ethylpentane, etc. It is also suitable for cyclopentaphylophenyls, such as and cyclohexanes, and methylcyclopentane, dimethylcyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, etc. The present inventive process is also applicable to mixtures of paraffins and / or naphthenes, including those derived from naphtha and natural gasoline. Examples of such mixtures of paraffins and / or naphthenes include the so-called pentane fractions, hexane fractions and mixtures thereof. The present invention is not limited in its scope to the listed saturated hydrocarbons. It is possible that Si-chain or branched chain saturated hydrocarbons containing up to 20 carbon atoms per molecule may be isomerized within the scope of the present invention. A preferred class of isomerizable hydrocarbons includes those hydrocarbons having from four to seven carbon atoms per molecule.

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Direct hydrocarbons suitable for the process of this invention may contain sulfur compounds in an amount ranging from 1 ppm (w / w) to about 300 ppm (w / w), based on elemental sulfur. An advantage of the present invention is that the combined feed to the isomerization reaction zone may contain H 2 S and / or organosulfur compounds in an amount that provides an elemental sulfur concentration of about 5 ppm (w / w) to about 200 ppm (w / w) in the combined feed. The term "combined feed" as used herein means a mixture of process streams that comes into contact with an isomerization catalyst. Those process streams include fresh isomerizable hydrocarbons, recycled isomerizable hydrocarbons, H2-rich light hydrocarbons, recycled H2-rich light hydrocarbons, and / or any other compounds that are desired to be added to the isomerization reaction zone. The term "H 2 -rich light hydrocarbons" as used herein means a process stream containing at least 50 mole percent H 2 with the remainder being C 1 -C 6 hydrocarbons. Recycled H2-rich light hydrocarbons are usually obtained from the product separation equipment of the isomerization process.

The level of sulfur in the combined feed may exceed the preferred maximum level of 200 ppm (by weight) when sulfur accumulation occurs. This results from the recycling of H2-rich light hydrocarbons containing measurable amounts of sulfur, typically in the form of H2S. H2S is formed when sulfur compounds associated with the isomerizable hydrocarbons change in the isomerization reaction zone. Thus, H2S is distinguished due to its high volatility, together with H2-rich light hydrocarbons in product separation equipment. As more and more of the sulfur compounds change in the Hiium reaction zone, the level of H2S in the recycle stream continuously increases, reaching a equilibrium level corresponding to the operating conditions of the product separator.

Thus, when the recycle stream is mixed with other process streams to form a combined feed, the total amount of sulfur in the combined feed increases to a level 20 to about 80% greater than the sulfur level in the fresh feed, depending on the separator temperature and pressure.

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Thus, one embodiment of the present invention is to control the level of sulfur in the combined feed in the range of about 5 to 150 ppm (by weight). Any means of control known in the art can be used, including catalytic conversion, physical or chemical adsorption, physical separation, and the like. One preferred control method is to prevent the recycling of rich light hydrocarbons from the product separation plant. This arrangement would prevent the accumulation of sulfur described above from occurring. In another preferred method, to control the level of sulfur contained in the combined feed, the recycled H2-rich light hydrocarbons are subjected to a desulfurization process prior to addition to the combined feed.

This removal process can reduce or eliminate sulfur compounds from recycled H2-rich light hydrocarbons by any method known in the art, including adsorption processes, catalytic processes, or combinations thereof. Molecular sieves, high surface area aluminas, carbon molecular sieves, crystalline aluminosilicates, activated carbon and the like can be used in the adsorption processes. Catalytic processes can use conventional sulfur-reducing catalyst formulations known in the art, including refractory inorganic oxide support materials containing metals selected from the group consisting of Group VIB, Group IIB, and Group VIII metals. The amount of sulfur control can be varied to achieve the desired level of sulfur in the combined feed. Low levels of sulfur in fresh isomerizable hydrocarbons (5-150 ppm) do not require desulfurization of recycled ^ -rich light hydrocarbons because sufficiently low levels of recyclable H2S (§ 100 ppm) can be maintained through H2S losses in the fresh separator liquid, and conversely, a high level of sulfur in a fresh isomerizable hydrocarbon (§ 150 ppm) may require the removal of sulfur from recycled H2-rich light hydrocarbons.

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A large number of experiments were performed to investigate how surface changes in isomerization catalyst compositions affect isomerization performance. Five catalysts were prepared for evaluation. In all the catalyst preparations described in the following examples, the starting material was a hydrogen-shaped, low-thrust, partially dealuminized synthetic mordenite powder (marketed by Union Carbide as LZ-M-8), hereinafter referred to as established mordenite.

Example I

In this example, a process for formulating a catalyst designated Catalyst A was not in accordance with the present invention. A 9: 1 weight ratio mixture of stabilized mordenite and alumina was mixed with the acidified peptizing solution and extruded (extruded through a die) in a manner known in the art. The extruded mixture was dried, calcined in an oxidative atmosphere, saturated with platinum and calcined again. Platinum was added to 0.324% by weight, based on the weight of the finished catalyst.

2

The surface area of Catalyst A was measured to be 567 m / g, and the surface area was correlated with the isomerization performance of the catalyst.

This correlation is shown graphically in Figure 1 below.

Example II

The catalyst composition of this example was designated Catalyst B, nor was it prepared in accordance with the present invention. The stabilized mordenite powder was contacted with an acidic aqueous solution containing ammonium ions comprising 10% by weight HCl and 10% by weight NH 4 Cl at 60 ° C for 150 minutes with a weight ratio of zeolite to 5: 1. The resulting mordenite powder was washed with H 2 O and calcined before mixing with alumina and peptizing solution. Extrusion and addition of platinum were performed on Catalyst B in a similar manner to Catalyst A in Example I. The platinum level of Catalyst B was 0.321% by weight. The area of Catalyst B was measured to be 534 m / g, and the area was correlated with isomerization performance as shown in Figure 1 of the Annex.

15? 6 6 3 2

Example III

Catalyst C prepared according to the invention was formulated in substantially the same manner as Catalyst A in Example I. However, according to the present invention, the dry extrudate was contacted with an aqueous acid solution containing ammonium ions before calcination and addition of platinum. This solution contained 10% by weight of HCl and 10% by weight of NH 4 Cl. The combination of the solution and the extrudate was performed at 60 ° C for 120 minutes with a weight ratio of solution to zeolite of 25: 1. Subsequently, the extrudate was dried, calcined and treated with platinum following the same procedures as for Catalysts A and B. The platinum level of Catalyst C was 0.396% by weight. The area 2 of Catalyst C was measured to be 622 m / g, and the area was correlated with the isomerization performance of the catalyst, as shown in Figure 1 below.

Example IV

The calcined extruded composition of Example II was combined with an acidic aqueous solution in the same manner as for Catalyst C in Example III before the platinum was added a second time. This second contact of the formed composition with the acidic aqueous solution is in accordance with the present invention. Platinum was then added to the composition to a level of 0.308% by weight, and this was designated Catalyst D. The surface area of Catalyst D was measured to be 630 m / g and correlated with isomerization. This correlation is illustrated in Figure 1 below.

Example V

Catalyst E was formulated in the same manner as Catalyst A, except that the acidity of the peptizing solution was reduced by 90%. As in Example I, Catalyst E was not formulated in accordance with the present invention. The platinum level of Catalyst E was 0.313% by weight. The surface area of Catalyst E was measured to be 542 m / g, and the surface area was correlated with the test results for the isomerization performance of the catalyst. This correlation is shown in Figure 1 below.

86632 BC

Example VI

The five catalyst formulations of Examples I to V containing platinum on the surface of the hydrogen mordenite gamma-aluminum composition were evaluated for their isomerization performance in a flow reactor treated with a feed containing a mixture of 46% by weight of n-pentane, 47.0% by weight. -% n-hexane, 5.5% by weight of methylcyclopentane and 1.5% by weight of benzene.

The operating conditions used to test the isomerization performance of Catalysts A to E included a reactor pressure of 2170 kPa, an hourly liquid flow rate of 1.0 h, a molar ratio of H 2 O to a hydrocarbon of 1.0, and temperatures ranging from 254 ° C to 277 ° C. The test run results, in particular the selectivity to isopentane (i-C 2) and 2,2-dimethylbutane (2.2 DMB) in 97% w / w yield, were used as a measure of isomerization performance. The selectivity value for i-C 1, shown in the accompanying Figure 1, is defined as the weight fraction of i-C 2 in the liquid isomerization product divided by the weight fraction of the total amount of C 1 -C 2 hydrocarbon in the product. To obtain the selectivity value of 2.2 DMB shown in Figure 1, the weight fraction of 2.2 DMB in the liquid isomerization product is divided by the weight fraction of the total, non-cyclic C8 hydrocarbon in the product.

Under the isomerization test run conditions used in the above examples, the selectivities for i-Cl 2 and 2.2 DMB are a direct function of the measured surface area of the finished catalyst. As graphically illustrated in Figure 1 below, the selectivities for i-Cl 2 and 2.2 DMB increase with increasing surface area. Catalyst C from Example III and Catalyst D from Example IV appear to have the highest selectivities for i-C, and 2.2 DMB according to the invention, each having a measured surface area of at least 580 m / g. A comparison of the platinum levels in Catalysts C and D with each other and with the other three catalysts shows that the platinum level does not correlate with the isomerization performance, further concretizing the benefit achieved with catalyst compositions having surface areas of at least 580 m / g. Thus, by utilizing the catalytic composition of the present invention, catalysts having excellent isomerization performance are produced.

Example VII

Two isomerization process experiments were performed to investigate the effect of sulfur-containing feedstocks on isomerization performance. In the first process, designated Process A, an isomerization catalyst having a surface area not in accordance with the present invention was utilized. Process A was tested to demonstrate isomerization performance when the sulfur-containing feed is subjected to a conventional prior art isomerization catalyst. The catalyst used was identical to Catalyst A of Example I.

The second process, designated Process B, was in accordance with the present invention and utilized Catalyst C formulated in Example IV in accordance with the present invention.

Processes A and B were evaluated for isomerization performance in a flow reactor treated with a feed comprising a mixture of 6.8 wt% butane, 20.9 wt% n-pentane, 14.5 wt% i-pentane, 15.7 wt% % n-hexane, 19.0 wt% i-hexane, 12.4 wt% cyclopentanes / cyclohexanes and 2.5 wt% benzene, 8.2 wt% Cg + and 133 ppm (w / w) sulfur.

The operating conditions used to test the isomerization performance of processes A and B included a reactor pressure of 3200 kPa, an hourly liquid flow rate of 1.0 h in a molar ratio of 2.0 to the hydrocarbon feed, and temperatures ranging from 254 ° C to 316 ° C. The Research octane number (RON-O) of the liquid C 2+ product, the average reactor catalyst bed temperature, and the% by weight of C 1+ yield were used to determine the isomerization performance. RON-O is shown in the accompanying Figures 2, 3 and 3 as a function of both the average reactor bed temperature and the C 1 - + yield. The process of this invention, Process B, includes a significant activity advantage over the conventional isomerization process, Process A, which uses a prior art catalyst. This is illustrated by the lower 32.2 ° C temperature requirement in Figure 2 to achieve RON-O 78. Process B also involves a significant octane advantage C, of up to four digits, in a yield of 94% by weight, compared to process A, as shown in Figure 2.

These examples clearly demonstrate the superior performance of the present invention when compared to the isomerization performance achieved by a conventional process using a prior art catalyst. A comparison in equivalent product yields shows that the invention of this application contains higher isomerization activity with increased octane value of the product. Conversely, a comparison in equivalent product octane values (e.g.

78 RON) indicates that the invention of this application has a higher product yield.

Claims (13)

A catalytic composition for isomerization of isomerizable hydrocarbons, characterized in that a combination of a metal component of the platinum group together with a carrier containing a crystalline mordenite in hydrogen and a refractory inorganic oxide, the surface area of said catalytic composition being at least 580 m 2 / g. Composition according to claim 1, characterized in that the metal component of the platinum group is platinum present in an amount of 0.1-0.5% by weight of the amount of the catalytic composition. Composition according to claim 1, characterized in that the ratio of silica to alumina of the hydrogen crystalline mordenite is at least 16: 1. Composition according to claim 1, characterized in that the hydrogen crystalline mordenite is present in an amount of 75-95% by weight of the composition. Composition according to claim 1, characterized in that the refractory inorganic oxide is alumina selected from the group consisting of gamma-alumina beta-alumina and mixtures thereof. Process for the preparation of a catalytic isomerization composition according to claim 1, characterized in that it comprises the following steps: (a) forming a composition containing hydrogen mordenite and refractory inorganic oxide; (b) calcining said composition; (C) subjecting said composition to contact with an acidic aqueous solution containing ammonium ions, under conditions selected to produce a final catalytic composition whose surface area is at least 580 m 2 / g; (d) calcining said contacted composition; and (e) incorporating a platinum group metal component with the calcined composition formed at step (d). Process according to Claim 6, characterized in that the metal component of the platinum group is platinum present in an amount of 0.15-0.5% by weight of the catalytic composition. An isomerization process for isomerizable hydrocarbons, characterized in that it comprises bringing a feed stream containing said isomerizable hydrocarbons and a hydrogen stream under isomerization conditions into contact with a catalyst composition having the features of any of claims 1-5. Process according to claim 8, characterized in that the isomerizable hydrocarbons comprise normal paraffins containing 4-7 carbon atoms per molecule. Process according to claim 8, characterized in that the isomerizing conditions consist of a temperature in the range 93-427 ° C, a pressure of 690-6895 kPa as a pressure gauge, the volume flow rate per hour of 0.25-5 h and a mole ratio of hydrogen to hydrocarbon of 0.5-5 moles of I / mole of the isomerizable hydrocarbon. Process according to Claim 8, characterized in that the combination of the input hydrocarbon stream and the hydrogen stream contains sulfur compounds in an amount of 5-200 ppm (weight) of the combination based on elemental sulfur. 23 86632 Process according to claim 11, characterized in that the amount of the sulfur charged to the process is controlled without circulating from a product separating device, H2-rich light hydrocarbons. Process according to claim 11, characterized in that the amount of the sulfur charged to the process is regulated by exposing a circulating, H2-rich stream of light hydrocarbons from a product separation device to a sulfur separation process before entering the process.