MXPA95002248A - Catalytic process for the isomerization of parafines with prototipos superaci - Google Patents

Abstract

The present invention relates to a catalytic process for the isomerization of a light paraffin, such as the pentane molecule, characterized in that, starting from a feed stream constituted by a hydrocarbon and a reaction medium, which can be hydrogen; The reaction is carried out according to the following sequence. Said process consists of several stages which consist of: preparation of the charge that can be of a saturated hydrocarbon, activation of the prototype superacid catalyst and isomerization reaction in prototypes of Pt / ZrOz and mixtures with SiO2 (5, 10, 15, 20 , 25%), activated at a temperature between 400 -600 ° C, followed by the isomerization reaction and the analysis of the product between 150 - 350 ° C. The use of this type of solid catalysts of super-acid nature abate the high conditions required for temperature and pressure, which are normally necessary when using catalysts such as aluminas, zeolites, or silicoaluminates of moderate acidity. At the same time, the low temperature of the reaction leads to the fact that the synthesized catalyst prototype was not deactivated.

Description

CATALYTIC PROCESS FOR THE ISOMERIZATION OF PARAFFIN WITH SUPERIOR PROTOTYPES. # DESCRIPTION TECHNICAL FIELD OF THE INVENTION The present invention relates to a catalytic process for the isomerization of a light paraffin; such as the pentane molecule, characterized in that from a current of - »feed constituted by a hydrocarbon and a reaction medium, which may be hydrogen; The reaction is carried out according to the following sequence. Said process consists of several stages which consist of: preparation of the cargo that can be of a saturated hydrocarbon; activation of the super-acid prototype catalyst and isomerization reaction in prototypes of Pt / Zr? 2 and mixtures with Si? 2 (5, 10, 15, 20, 25%), activated at a temperature comprised A * between 400 - 600 ° C, followed by the isomerization reaction and the analysis of the product between 150 - 350 ° C. The use of this type of solid catalysts of superacid nature abate the high conditions required for temperature and pressure, which are normally necessary when using catalysts such as; aluminas, zeolites, or silicoaluminates of moderate acidity. In turn, the low temperature of the reaction leads to the prototype -k of the synthesized catalyst not being deactivated.

BACKGROUND OF THE INVENTION The isomerization reactions of hydrocarbons are of great importance because they create high reactivity molecules, which serve as raw material for the synthesis of infinite intermediate and end-use products. The most commonly used paraffins are those derived from hydrocarbon molecules of paraffinic nature of four, five or more carbon atoms, with butane and pentane being the most studied hydrocarbons. In Japanese Patent 87-344276 / 49, a process is described for the production of a catalyst which was prepared by impregnating a support (hydroxide or oxide) of group III or IV of the periodic table, with a metal of group VIII , In the Japanese patent 61-2633932 of November 1986, in which a catalyst was obtained by impregnating a Group VIII metal, for example; nickel, platinum, ruthenium, palladium, rhodium, osmium and iridium, with a precursor sulphate ion, deposited on a support made from Group IV metals such as titanium, zirconium, silicon, germanium or iron and hydroxides or oxides of the group III, based on aluminum, gallium, indium and thallium.

In Japanese Patent 62-246963 of April 2, 1986, a process is described for cracking paraffins by the use of hydrogen, an operation known as hydrocracking. Which is carried out thermally between 150 - 350 ° C, at 50 atmospheres of pressure and in the presence of a solid material. The catalyst used was manufactured from impregnating a metal of group VIII, such as nickel, platinum, ruthenium, rhodium and palladium, on A group III or IV hydroxide or oxide matrix, followed by a sulfuric acid treatment to complete a stabilization of the catalyst.

In the American patent 3 '678, 120 of July 18 of 1972, in which a catalyst was obtained from SbF3-HS03F. This has been particularly active for isomerization, alkylation and polymerization reactions.

In the American patent 3 '975, 299 of August 17 of 1976, in which the process for the production of a catalyst of acid nature (Ho = -3), of generic formula XF- > synthesized from phosphorus, arsenic, bismuth, tantalum, vanadium, and / or niobium; embedded in an alumina matrix.

* In accordance with the present invention, an improved catalytic process for the isomerization of pentane with superacid prototypes is described, which is carried out in a series of steps comprising among others: 1. - Preparation of the feed charge, where the hydrocarbon stream to be isomerized, previously dried, is fed by a The reaction medium can be a gas. The mixture thus formed is subjected to a preheating. 2. - Preparation of the super acid material from the respective alkoxides obtained from the sol-gel process. Subsequently sulfating the EB-material with H2SO4 IM under controlled conditions. 3. Activation of the catalyst, which is carried out by passing a stream of dry air over the catalytic bed at the temperature at which the sites capable of carrying out the reaction are activated, that is temperatures between 400-650 ° C, preferably 500 ° C and for a time comprised between one and 4 hours, preferably three hours. 4. - Isomerization reaction of hydrocarbon fed, which may contain five or more carbon atoms, in the presence of a platinum-zirconia oxide catalyst and / or mixture with silicon oxide, at a temperature of 150-300 ° C and atmospheric pressure (585/760 m »Hg).

. - Isomerization reaction of the hydrocarbon fed, which may contain five or more carbon atoms, in the presence of a catalyst • Pt-oxide of zirconia / silicon oxide, at a temperature of 150-300 ° C and atmospheric pressure (585/760 mm Hg), characterized the process because the reaction is carried out through the use of a system constituted by a gas, preferably hydrogen.

The invention also provides an improved catalytic process for the preparation of 20 isomers of light paraffins, which works with a more active catalyst than the conventional ones based on Pt-Zr? 2 / Si? 2, which allows increase the volume of production.

In addition, the invention provides an improved catalytic process for obtaining isomers of light paraffins, where a highly selective catalyst is used for paraffins from hydrocarbons of five carbon atoms, which reduces the complexity and therefore the cost of the stage of reaction and * consequently of separation.

Additionally, the present invention provides an improved catalytic process for obtaining isomers of light paraffins that allows to operate under pressures around atmospheric pressure and relatively low temperatures, in comparison with conventional isomerization processes.

These and other objects of this invention will be illustrated with greater clarity and detail in the following chapters, in which the best method known by the applicant to bring it into practice is described.

BRIEF DESCRIPTION OF THE DRAWINGS.

In order to have a clearer knowledge of the process that will be described next, we have the following figure.

Figure 1 is a diagram of the process for obtaining isomers of paraffins in which each of the stages thereof is shown.

DETAILED DESCRIPTION OF THE INVENTION The improved catalytic process for the production of light olefins according to the present invention, enunciatively comprises several steps such as, for example: I Preparation of the feed charge.

# II Activation of the catalyst. 10 III Isomerization reaction. IV Analysis and quantification of the product.

Said stages can be developed successively and are integrated in such a way that together they define a global scheme for the continuous obtaining of parafine isomers of five carbon atoms.

The feed stream (A) is pre-heated in line at a temperature of 20-50 ° C. The feed is composed of the hydrocarbon to be isomerized mixed with hydrogen at the pre-established saturation temperature. While preparing the charge in parallel to the reactor, the catalyst is activated by a stream of hydrogen at 400-550, preferably 500 ° C for two hours, stream (B). The current of < * feed already prepared is fed to a simple tubular reactor, packed with the catalyst. The isomerization reaction of the hydrocarbon is carried out inside the reactor (C). When contacting the charge with the catalyst at a temperature between 150 - 350 ° C, pressure of 0.7 to 1.0 atmospheres, space velocity of 2.5 to 3.5 h ", and evaluation of the activity between 0-5 10 hours, preferably 4 hours.

Regarding the installation (C) of a double reaction system, it must be installed if the microplant is to be operated in a continuous mode, in addition the operation of this second reaction unit allows us to alternatively regenerate the material located inside the reactor bed. which can be activated or regenerated by using one? hydrogen stream at a temperature of 400-550 ° C, preferably 500 ° C, during an exposure time of 4 hours.

On the other hand, it is necessary to keep the pentane in the gas phase during the course of the operation; that is before the passage through the reactor and after the reaction is carried out, wherein the fed pentane has reacted, the corresponding isomer being produced preferentially, ie isopentane. Which is fed to the detection system constituted by the chromatographic analysis, using exprofeso a flame ionization detector and a capillary column system.

The scheme of the process described above works correctly on an industrial scale, according to its design, operating conditions, loads and arrangement, or arrangement of the mentioned stages, high selectivities and average conversions are obtained towards the corresponding isomer of the paraffin used. The process also allows the continuous production of olefin isomers by the effect of operating alternatively two or more reaction units.

The following practical examples are mentioned below in order to illustrate the present one better, without limiting the scope of the invention.

Example 1 The synthesis was carried out by the sol-gel technique. In a pyrex glass reactor, which contains four mouths for addition funnel, coolant, mechanical stirrer and thermometer. They are placed in the reactor: 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid. At room temperature they are added * 70.5 ml of silicon tetraethoxide and the reactor is heated in order to maintain the reflux condition (Tebii. 78 C) corresponding to the ethyl alcohol, maintaining the synthesis reaction with controlled agitation (both steps necessary to control gelation) for 2 hours. Subsequently the system is cooled to a temperature of 10 20 C and a mixture of 3.7 ml of zirconium tert-butoxide in 20 ml of ethyl alcohol is added after 4 hours of reflux, the white-colored gelled product is formed "condition necessary to be able to quantify Hammett acidity. " The Zr? 2-Si? 2 structures are formed, or variable compositions between 5 and 25%. of Zr? 2. The samples were sulfated with H2SO4IN, drying at a controlled temperature. 100 ° C. The material thus synthesized is then dried under mechanical JP vacuum conditions for 4 hours, at this point the acidity of the sample has been determined, whose values are presented in Table 1 through the use of Hammett indicators. To synthesize the platinum-based catalysts, a solution of 8 mg / ml concentration of chloroplatinic acid dissolved in ethyl alcohol was prepared. For all cases a metal / support ratio of 0.5% weight and 10 ml of ethyl alcohol / gram of support was maintained. We proceeded to impregnate the support to dryness, then the samples were activated in a temperature controlled oven, in air flow at 400 ° C for 5 hours, finally the acidity of the catalyst was determined by the use of Hammett indicators.

Table 1. Determination of Hammett acidity in superacids.

Sample Sulphated Sulfated Sulfated Pt / 5% Zr02-95% Si02 -0.9 -13.75 Pt / 10% Zr? 2-90% Si? 2 -2.4 -13.75 Pt / 15% Zr? 2-85% Yes? 2 -0.2 -12.70 Pt / 25 % Zr? 2-75% Yes? 2 -4.3 -12.70 Pt / 100% Zr02 -0.2 -9.30 Pt / 100% Si02 -4.3 -16.00 To carry out the experimental part, a reaction device was designed, or a reaction micro-plant, which consists mainly of three sections: feeding, reaction and analysis; already described above. Using a glass reactor provided with a porous plate to deposit the catalyst synthesized and activated, by means of an electric furnace, the temperature of the catalytic bed was varied within certain permissible limits, that is to say where the behavior of the catalyst varies linearly with the conversion or selectivity to the desired product. The degree reached by each of the aforementioned parameters is illustrated in the following table: Table 2. Determination of activity in prototypes exceeded.

Sample Conversion Selectivity (%) (%) Pt / 5% Zr? 2-95% Si? 2 14.4 100 Pt / 10% Zr? 2-90% Si? 2 16.6 98 Pt / 15% Zr? 2-85% Si? 2 24.9 92 Pt / 25 % Zr? 2-75% Yes? 2 19.6 88 Pt / 100% Zr? 2 10.6 90 Pt / 100% Si? 2 5.2 89 20 Reactor temperature 300 C, WHSV = 2.5 h-i- With: Conversion .- is the degree of conversion in% molar, defined as% paraffin or pentane, converted into the sum of all products. Selectivity .- is defined as the quotient of the amount of isopentane obtained and the amount of pentane converted in all products and normalized to a factor of percent.

Under the conditions imposed on the reaction, the degree of conversion of pentane that can be reached in the thermodynamic equilibrium is approximately 100%. The selectivity is practically total towards the product of interest, and for this case in particular the selectivity or conversion varies with the space-velocity used in the evaluation and the temperature of the reactor.

Example 2 The prototype Pt / 10% Zr? 2-90% Si? 2 M p-0 described according to its activity in the corresponding table 2 was evaluated in a microplant with catalytic activity operating in integral kinetic regime and continuous flow. was synthesized from the sol-gel technique, maintaining the reaction system described in example 1. In a pyrex glass reactor, which contains four mouths for addition funnel, coolant, mechanical stirrer and thermometer. They are placed in the reactor: 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid. At room temperature, 66.8 ml of silicon tetraethoxide are added and the reactor is heated in order to maintain the reflux condition corresponding to ethyl alcohol for 2 hours.

Subsequently, the system is cooled to a temperature of 20 C and a mixture of 7.4 ml of zirconium terbutoxide in 20 ml of ethyl alcohol is added after 4 hours of reflux to form the gelled product. The subsequent steps of acidification, drying, impregnation and catalyst activation have been maintained as described in the previous example.

The experimentation was carried out at a controlled temperature of 250 ° C. For the prototype described the degree of conversion, although; has increased this has been controlled. The percentage of conversion was 16.6% and the selectivity towards isopentane 98%.

-C Example 3 20 In a microplant with catalytic activity operating in integral kinetic regime and continuous flow, the prototype Pt / 15% Zr? 2-85% Si? 2 was evaluated according to its activity. In the corresponding table 2, the results obtained for this preparation are shown, which was synthesized from the sol-gel technique. They are placed in the reactor: 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid. At room temperature 78.9 ml of silicon tetraethoxide are added and the reactor is heated in order to keep the system in reflux corresponding to ethyl alcohol, maintaining the synthesis reaction with controlled agitation for 2 hours. Subsequently, the system is cooled to 20 C and a mixture of 13.9 ml of zirconium terbutoxide in 20 ml of ethyl alcohol is added; after 4 hours of reflux, the gelled product 10 is formed. The subsequent steps of acidification, drying, impregnation and catalyst activation have been maintained as described in example 1.

In order to evaluate the conversion percentage reached by this system, it has been maintained at 250 ° C, proceeding to determine its activity. The result obtained indicates that the maximum conversion has been reached for this catalyst. In parallel, figure 2 shows the maximum conversion achieved for this prototype and the degree of stability or percentage of deactivation in this sample.

Example 4 In a microplant of catalytic activity operating in integral kinetic regime and continuous flow, the prototype Pt / 25 Zr? 2-75% Si? 2 was evaluated, being synthesized from the sol-gel technique, as described in Example 1. 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid were reacted. At room temperature, 83.5 ml of silicon tetraethoxide are added and the reactor is heated in order to maintain the reflux condition, maintaining the synthesis reaction with controlled stirring also for 2 hours. Subsequently, a mixture of 7. 4 ml of zirconium terbutoxide in 20 ml of ethyl alcohol after 4 hours of reflux is used to form the # gelled product. The subsequent steps of acidification, drying, impregnation and catalyst activation have been maintained as described in example 1.

The experimentation was carried out at 300 C for the prototype described, the degree of conversion was 19.6%, together with a high percentage of selectivity • [88%} . 20 Example 5 In a microplant with catalytic activity operating in the integral kinetic and continuous flow regime, the prototype Pt / 100% Zr02 described according to its activity was evaluated in the corresponding table 1, as described in the previous examples 1 to 4. it reacted 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid. 92.8 ml of zirconium terbutoxide previously dissolved in 70 ml of ethanol was added, the reactor is heated in order to maintain the reflux condition corresponding to the alcohol, the synthesis reaction being maintained with controlled agitation for 2 hours. The subsequent stages of acidification, drying, Catalyst impregnation and activation have been maintained as described in example 1.

The experimentation was carried out at 250 ° C for the prototype described, the degree of conversion although it has decreased in comparison with the case analyzed with example one, this one is still significant [10.6%].

Example 6 jj ^ 20 In a microplant with catalytic activity operating in integral kinetic regime and continuous flow, the prototype Pt / 100% Si? 2 was evaluated, described according to its activity in the corresponding table 1, it was synthesized from the technique sol-gel. They are placed in the reactor: 47 ml of bidistilled water, 80 ml of ethyl alcohol and 2 ml of hydrochloric acid. 74.2 ml of silicon tetraethoxide are added and the reactor is heated in order to maintain the

Claims (9)

1. reflux condition corresponding to the alcohol, the reaction being maintained for 2 hours. The stages Subsequent acidification, drying, impregnation and catalyst activation have been maintained as described in example 1. The experimentation was carried out at a temperature of 250 ° C. The degree of conversion has decreased to 5%, the loss of activity is associated with the 10 acidity of the support and the degree of dispersion of the metal in the • matrix. CLAIMS 1. - An improved catalytic process for the isomerization of light paraffins in order to obtain isomers of paraffins, from a stream composed of hydrocarbons to be isomerized and a reaction medium which can be a gas in the presence of a catalyst, characterized by the following stages: Preparation of the feed stream formed by the hydrocarbon to be isomerized mixed with a reaction medium that can be hydrogen, at the time of mixing the feed is preheated from 0 to 20 ° C; feeding the mixed stream or alone to a tubular reactor to bring it into contact with a super oxide type material such as zirconia, the isomerization reaction of the hydrocarbon fed at a temperature of 150-300 C, and at atmospheric pressure being carried out . { 585/760 m Hg} , and for a period of 0 to 5 hours; preferably 2 hours. 2. - An improved catalytic process for the isomerization of light paraffins in order to obtain isomers of paraffins of five carbon atoms, according to clause 1, characterized in that the The hydrocarbon to be isomerized is fed with a reaction medium which may be hydrogen. 3. - An improved catalytic process for the isomerization of light paraffins in order to obtain paraffins of up to 5 carbon atoms, according to clauses 1 to 2, characterized in that it is necessary to preheat the feed mixture from 0 to 20 ° C. 4.- An improved catalytic process for the isomerization of light paraffins in order to obtain paraffins of up to 5 carbon atoms, in accordance with clauses 1 to 3, characterized in that the isomerization reaction is carried out in the gas phase at temperature between 150 - 300 ° C, pressure between 0.75 and 1.0 atmospheres, with a reaction period of three hours. # 5. - An improved catalytic process for the isomerization of light paraffins in order to obtain paraffins of up to 5 carbon atoms, according to clauses 1 to 4, characterized in that the isomerization reaction is carried out in phase J 10 ^ gaseous at a temperature between 150 - 300 ° C, pressure between 0.75 and 1.0 atmospheres, with prototypes of high acidity known as superacid materials, (low Ho) property that affects the high selectivity / conversion towards the respective branched paraffins together to a low or no production of light hydrocarbons. 6. - An improved catalytic process for the isomerization of light paraffins in order to obtain isomers of up to five carbon atoms, in accordance with clauses 1 to 5, characterized in that a series of platinum catalysts supported on zirconia oxide base is used - silica oxide, this type of synthesized material is particularly interspersed oxide phases of super-acid nature, determined by the use of Hammett indicators. 7. - An improved catalytic process 9 for the isomerization of light paraffins in order to obtain isomers of up to five carbon atoms, according to clauses 1 to 6, characterized in that when the platinum supported on zirconium oxide supported on Si? 2 is found, it is considerably increased the acidity of the samples favoring the selectivity towards the corresponding isomer. # 10 8.- An improved catalytic process for the isomerization of light paraffins in order to obtain isomers of up to five carbon atoms, in accordance with clauses 1 to 7, characterized in that the calcination is carried out at temperatures between 400 550 C, preferably 500 C for 3 hours in an oxidizing atmosphere of air or oxygen. * 9. - An improved catalytic process for the isomerization of light paraffins in order to obtain isomers of up to five carbon atoms, in accordance with clauses 1 to 6, characterized in that the samples of the reaction mixture are not deactivated in periods Reaction time of 4 hours. In testimony of which, I sign the present in the city of Mexico, D.F., to DIECISIETE of MAY, 1995. BY MEXICAN INSTITUTE OF PETROLEUM. • 2. 3