Catalyst for preparing n-butane, preparation method of catalyst and application of catalyst in preparation of n-butane

Abstract

The invention discloses a catalyst for preparing n-butane, a preparation method of the catalyst and application of the catalyst to preparation of the n-butane. The catalyst comprises an alkaline carrier, an active component, an auxiliary component I and an auxiliary component II, wherein the active component, the auxiliary component I and the auxiliary component II are loaded on the alkaline carrier; the alkaline carrier is an alkaline molecular sieve carrier; the active component comprises an active element, and the active element is iridium; the auxiliary agent component I is a gold element; the auxiliary agent component II is selected from at least one of zinc, copper, rhenium, cobalt, lanthanum, cerium, titanium, tungsten and nickel. The catalyst disclosed by the invention can efficiently catalyze the conversion of isobutane to n-butane under a chlorine-free condition.

Description

TECHNICAL FIELD

[0001] The application relates to a catalyst for preparing n-butane and a preparation method and application in the preparation of n-butane, and belongs to the technical field of catalyst preparation. BACKGROUND

[0002] In a petroleum processing process, isobutane in a mixed carbon four by-product is mainly used for dehydrogenation to prepare isobutene, and then used for the production of methyl tert-butyl ether (MTBE). Due to the influence of MTBE on the environment and the potential carcinogenic risk, MTBE is being banned in more and more countries, thereby leading to a decrease in the demand for isobutane. Converting isobutane in the mixed carbon four into n-butane which is in increasing demand is an effective way to realize the efficient utilization of carbon four resources. The key to realizing the above industrial process is the development of a high-performance isobutane n-butane preparation catalyst.

[0003] Patent US4191845A discloses a Pt metal-loaded chlorinated alumina catalyst for isobutane n-butane preparation. However, the catalyst needs to be continuously supplied with chlorine-containing compounds to maintain the acidity of the catalyst, thereby causing problems such as equipment corrosion and the presence of chlorine-containing impurities in the product. Patent CN110385142B discloses an isobutane n-butane preparation catalyst containing an SO4 2- / ZrO2 acidic component and a platinum metal active component. The catalyst can effectively convert isobutane under chlorine-free conditions. Under the conditions of a reaction pressure of 2.0 MPa, a reaction temperature of 330 DEG C and an isobutane mass space velocity of 2.0 h -1 , the isobutane conversion rate can reach 25.8%, and the n-butane selectivity is 85.4%. However, the zirconium sulfate oxide is prone to decomposition at a relatively high temperature, and sulfur-containing compounds are generated, thereby causing problems such as poor regeneration performance of the catalyst and environmental pollution. Patent CN111569861B discloses a supported superacid catalyst taking tungsten oxide, molybdenum oxide, phosphorus-tungsten composite oxide or phosphorus-molybdenum composite oxide as a carrier. The catalyst can effectively convert isobutane, but also has problems such as too strong acidity, too many side reactions and low selectivity of the target product. SUMMARY

[0004] In view of the problems of the existing isobutane n-butane preparation catalysts, the application aims to provide a n-butane preparation catalyst and application. The catalyst is used under chlorine-free conditions and has the characteristics of high catalytic activity and good selectivity.

[0005] According to one aspect of the application, a catalyst for preparing n-butane is provided, the catalyst comprising a basic carrier and an active component, an auxiliary component I and an auxiliary component II supported on the basic carrier;

[0006] The basic carrier is a basic molecular sieve carrier.

[0007] the active component comprises an active element, the active element being iridium;

[0008] the assistant component I is a gold element;

[0009] the assistant component II is selected from at least one of zinc, copper, rhenium, cobalt, lanthanum, cerium, titanium, tungsten, nickel elements.

[0010] Optionally, the basic carrier is a basic molecular sieve carrier, and a topological structure of the basic molecular sieve carrier is at least one of X type, Y type, L type.

[0011] Optionally, a skeleton charge balance cation of the basic molecular sieve is one of cesium ion or rubidium ion.

[0012] Optionally, a mass ratio of the iridium to the basic molecular sieve carrier is 0.0005-0.01:1, and the mass of the iridium is calculated according to the mass of iridium element.

[0013] Optionally, the mass ratio of the iridium to the basic molecular sieve carrier is independently selected from any value of 0.0005:1, 0.0001:1, 0.005:1, 0.001:1, 0.01:1 or a range value between any two of the above values.

[0014] Optionally, a mass ratio of the assistant component I to the basic molecular sieve carrier is 0.001-0.02:1.

[0015] Optionally, the mass ratio of the assistant component I to the basic molecular sieve carrier is independently selected from any value of 0.001:1, 0.005:1, 0.008:1, 0.01:1, 0.015:1, 0.02:1 or a range value between any two of the above values.

[0016] Optionally, a mass ratio of the assistant component II to the basic molecular sieve carrier is 0.005-0.05:1.

[0017] Optionally, the mass ratio of the assistant component II to the basic molecular sieve carrier is independently selected from any value of 0.005:1, 0.008:1, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1 or a range value between any two of the above values.

[0018] Optionally, the basic molecular sieve carrier is selected from at least one of X type, Y type, L type molecular sieve.

[0019] Optionally, a skeleton charge balance cation of the basic molecular sieve carrier is cesium ion and / or rubidium ion.

[0020] According to another aspect of the present application, there is provided a method for preparing the catalyst as described above, comprising the following steps:

[0021] (1) stirring and dissolving a mixture I containing an active component precursor, an auxiliary component I precursor, and water to obtain an impregnation solution I;

[0022] (2) stirring and dissolving a mixture II containing an auxiliary component II precursor and water to obtain an impregnation solution II;

[0023] (3) impregnating a basic molecular sieve carrier in the impregnation solution I, drying I, calcining I, and reducing to obtain a catalyst precursor;

[0024] (4) impregnating the catalyst precursor in the impregnation solution II, drying II, and calcining II to obtain the catalyst.

[0025] Optionally, in the step (1), the active component precursor is selected from at least one of chloroiridic acid, sodium chloroiridate, and ammonium chloroiridate.

[0026] Optionally, the auxiliary component I precursor is selected from at least one of chloroauric acid, sodium chloroaurate, and potassium chloroaurate.

[0027] Optionally, in the step (2), the auxiliary component II precursor is selected from at least one of nitrates, hydrochlorides, and sulfates of zinc, copper, rhenium, cobalt, lanthanum, cerium, titanium, tungsten, and nickel elements.

[0028] Optionally, the mass ratio of the active component precursor to the basic molecular sieve carrier is 0.0005-0.01:1, and the mass of the active component precursor is calculated based on the mass of the active element of the active component.

[0029] Optionally, the mass ratio of the auxiliary component I precursor to the basic molecular sieve carrier is 0.001-0.02:1, and the mass of the auxiliary component I precursor is calculated based on the mass of the auxiliary element of the auxiliary component I.

[0030] Optionally, the mass ratio of the auxiliary component II precursor to the basic molecular sieve carrier is 0.005-0.05:1, and the mass of the auxiliary component II precursor is calculated based on the mass of the auxiliary element of the auxiliary component II.

[0031] Optionally, in the step (3), the drying I is performed at a temperature of 80-150°C for 0.5-20h.

[0032] Optionally, the calcining I is performed at a temperature of 300-600°C for 0.5-10h.

[0033] Optionally, the reducing is performed in a hydrogen atmosphere.

[0034] Optionally, the hydrogen I has a volume hourly space velocity of 100-10000 h -1 .

[0035] Optionally, the reduction temperature is 200-500°C and the reduction time is 0.5-20 h.

[0036] Optionally, in the step (4), the temperature of the drying II is 80-150°C and the drying II time is 0.5-20 h.

[0037] Optionally, the temperature of the calcination II is 400-600°C and the calcination II time is 0.5-20 h.

[0038] According to still another aspect of the present application, there is provided a use of the above-mentioned catalyst in preparing n-butane, wherein the catalyst is pre-reduced by hydrogen I, and then contacted with a raw material containing isobutane and hydrogen to obtain n-butane.

[0039] Optionally, the pre-reduction atmosphere is hydrogen I.

[0040] Optionally, the hydrogen I has a volume hourly space velocity of 100-10000 h -1 .

[0041] Optionally, the volume hourly space velocity of the hydrogen I is independently selected from any value of 100 h -1 , 1000 h -1 , 2000 h -1 , 5000 h -1 , 8000 h -1 , 10000 h -1 or a range value between any two of the above.

[0042] Optionally, the pre-reduction temperature is 350-600°C and the pre-reduction time is 0.2-100 h.

[0043] Optionally, the pre-reduction temperature is independently selected from any value of 350°C, 400°C, 450°C, 500°C, 550°C, 600°C or a range value between any two of the above.

[0044] Optionally, the isobutane has a feed volume hourly space velocity of 50-10000 h -1 .

[0045] Optionally, the isobutane has a feed volume hourly space velocity independently selected from any value of 50 h -1 , 100 h -1 , 1000 h -1 , 2000 h -1 , 5000 h -1, 8000h -1 、10000h -1 Any value in or a range of values ​​between any two of the above.

[0046] Optionally, the molar ratio of the hydrogen to the isobutane is 0.2 to 10:1.

[0047] Optionally, the molar ratio of the hydrogen to the isobutane is independently selected from any value among 0.2:1, 0.5:1, 1:1, 2:1, 5:1, 10:1 or a range between any two of the above values.

[0048] Optionally, the temperature of the contact reaction is 300-500° C., and the pressure of the contact reaction is 0.1-10.0 MPa.

[0049] As an optional implementation scheme, the present application is implemented through the following technical solutions:

[0050] The n-butane catalyst preparation method comprises the following steps:

[0051] a) adding a noble metal active component precursor and an auxiliary component A precursor into deionized water, stirring and dissolving them to prepare an impregnation solution A;

[0052] b) adding the precursor of the auxiliary component B into deionized water, stirring and dissolving to prepare an impregnation solution B;

[0053] c) uniformly adding the impregnation solution obtained in step a) to the alkaline support until adsorption is saturated, then standing at room temperature, drying, roasting, and then reducing to prepare a solid sample A;

[0054] d) adding the impregnation solution B obtained in step b) evenly to the solid sample A obtained in step c) until adsorption saturation, then standing at room temperature, drying, and calcining at 400-600° C. to prepare the n-butane preparation catalyst.

[0055] The process of using n-butane to prepare the catalyst includes: firstly pre-reducing the catalyst loaded in the reactor with hydrogen; after the reduction is completed, introducing isobutane-rich raw materials and hydrogen to react.

[0056] To achieve the above application effects, optionally, the reactor is at least one of a fixed bed reactor, a moving bed reactor and a fluidized bed reactor.

[0057] The beneficial effects of this application include:

[0058] The catalyst carrier provided by the application is a basic molecular sieve, which has excellent pore structure and effective basic sites, meets effective diffusion of raw materials and products and skeleton isomerization of reaction intermediates, and inhibits carbon deposition on the surface of the catalyst, thereby improving the service life of the catalyst. The catalyst preparation method provided by the application is simple in process, easy to operate, good in repeatability, and suitable for large-scale industrial production. The catalyst can catalyze the isobutane normal-forming n-butane reaction to be efficiently performed, and has the characteristics of high catalytic activity, good selectivity and low deactivation. DETAILED DESCRIPTION

[0059] The application will be described in detail below in combination with examples, but the application is not limited to the examples.

[0060] Unless otherwise specified, the raw materials in the examples of the application are purchased through commercial channels, and the parameters of the instruments and equipment are set according to the recommended parameters of the manufacturers.

[0061] Preparation of basic molecular sieves B-1 to B-5

[0062] 30 g of a sodium-type molecular sieve matrix was put into a solution of a cesium precursor or a rubidium precursor with a concentration of 0.5 mol / L, ion exchange was carried out at a liquid-solid ratio of 10:1 mL / g and 80°C for 4 hours, then centrifugation was performed, the ion exchange was washed with deionized water, and drying was performed at 120°C, and calcination was performed at 550°C for 4 hours, and then the above process was repeated for 1 to 3 times. The type of the molecular sieve matrix of the basic molecular sieves B-1 to B-5, the type of the ion exchange precursor and the total number of exchanges are shown in Table 1.

[0063] Table 1 Preparation conditions of the basic molecular sieves B-1 to B-5

[0064] Basic molecular sieve Molecular sieve parent type Cation precursor species Total ion exchange B-1 X Cesium chloride 2 B-2 X Cesium chloride 3 B-3 X Rubidium chloride, 3 B-4 Y Rubidium chloride 3 B-5 L Cesium chloride 3

[0065] Preparation of catalysts C-1 to C-10

[0066] The basic molecular sieves B-1 to B-5 prepared in Example 1 were used as the matrix, and catalysts were prepared by using an equal-volume impregnation method.

[0067] The saturated water absorption of the basic molecular sieve was determined by a saturated adsorption method, then, according to the saturated water absorption of the basic molecular sieve and the target loadings of the iridium metal active component and the additive component A, the mass of the iridium metal active component precursor and the additive component A precursor required for preparing the impregnation precursor solution was calculated. According to the calculation results, the noble metal active component precursor and the additive component A precursor with the required mass were added to deionized water, stirred and dissolved to prepare the impregnation precursor solution. The impregnation precursor solution was uniformly added to the basic molecular sieve until adsorption saturation, then the mixture was left to dry at room temperature, dried at 120°C for 4 hours, and then calcined at 500°C for 6 hours. The calcined sample was subjected to a n-butane normal-forming reaction at a volume space velocity of 1000 h -1The catalyst was reduced at 300 °C in a hydrogen atmosphere for 4 h to obtain a semi-finished catalyst.

[0068] Based on the saturated water absorption of the alkaline molecular sieve and the target loading of auxiliary component B, calculate the mass of auxiliary component B precursor required for the impregnation precursor solution. Based on the calculated results, add the required mass of auxiliary component B precursor to deionized water and stir to dissolve, thereby preparing the impregnation precursor solution. This impregnation precursor solution is evenly added to the semi-finished catalyst until adsorption saturation occurs. The catalyst is then allowed to dry at room temperature, oven-dried at 120°C for 4 hours, and calcined at 500°C for 4 hours. Catalysts C-1 to C-10 are obtained.

[0069] The preparation conditions used in the preparation of the above-mentioned catalyst, including the alkaline molecular sieve support, the type of iridium metal active component precursor, the type of auxiliary component A precursor, the type of auxiliary component B precursor, the iridium metal loading (in terms of precious metal elements, the mass ratio of the iridium metal loading to the alkaline molecular sieve support), the auxiliary component A loading (in terms of metal elements, the mass ratio of the iridium metal loading to the alkaline molecular sieve support), the auxiliary component B loading (in terms of metal elements, the mass ratio of the iridium metal loading to the alkaline molecular sieve support), and the calcination temperature, are shown in Table 2.

[0070] Table 2 Preparation conditions of catalysts C-1 to C-10

[0071]

[0072] Comparative Example 1

[0073] The catalyst of Comparative Example 1 was prepared using sodium molecular sieve as the matrix according to the preparation method of catalyst C-2 in Example 2.

[0074] Comparative Example 2

[0075] Using the basic molecular sieve B-2 in Example 2 as the matrix, the catalyst of Comparative Example 2 with a gold loading of 0.5 wt% and a copper loading of 2.5 wt% was prepared according to the loading method of the A and B additives in Catalyst C-2.

[0076] Example 3 Evaluation of Catalyst Isobutane Normal Activity

[0077] The catalytic performance of the catalysts C-1 to C-10 prepared in Example 2 and the catalysts of Comparative Examples 1 and 2 was evaluated for the conversion of isobutane to n-butane. A fixed bed reactor was used with an inner diameter of 8 mm and a catalyst loading of 2 mL. The catalyst was first heated at a volume space velocity of 1000 h -1 The reaction was carried out in a hydrogen atmosphere for 4 hours, followed by the introduction of feedstock containing isobutane and hydrogen. The product was analyzed online using an Agilent 7890A chromatograph. Catalyst activity was evaluated using indicators such as isobutane conversion and n-butane selectivity. The calculation methods for these indicators are as follows:

[0078]

[0079]

[0080] [isobutane] 进 represents the molar flow rate (mol / h) of isobutane at the reactor inlet; [isobutane] 出 and [n-butane] 出 respectively represent the molar flow rate (mol / h) of isobutane and n-butane at the reactor outlet. The catalysts, catalyst reduction temperature, reaction conditions and isobutane n-alkane reactivity of the catalysts of experiments exp 1 to exp 13 are shown in Table 2.

[0081] Table 2 Reaction conditions and catalyst activity of experiments exp 1 to exp 13

[0082]

[0083] In the experiments shown in Table 2, the reaction was sampled and analyzed once every 2h, and the reaction results in the table are the average values of 30h. Among them, experiment exp 2 was continuously operated for 1000h, and no obvious decrease in conversion rate and selectivity was observed, indicating that the catalyst has good stability.

[0084] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed as the above preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which is equivalent to the equivalent embodiments, and belongs to the scope of the technical solution.

Claims

1. A catalyst for the production of n-butane, characterized in that, The catalyst comprises a basic carrier and active component, auxiliary component I and auxiliary component II supported on the basic carrier; The basic carrier is a basic molecular sieve carrier; The active component comprises an active element, and the active element is iridium; The auxiliary component I is a gold element; The auxiliary component II is selected from at least one of zinc, copper, rhenium, cobalt, lanthanum, cerium, titanium, tungsten and nickel elements.

2. The catalyst according to claim 1, characterized in that, The mass ratio of the iridium to the basic molecular sieve carrier is 0.0005-0.01:1, and the mass of the iridium is calculated according to the mass of the iridium element; Preferably, the mass ratio of the auxiliary component I to the basic molecular sieve carrier is 0.001-0.02:1; Preferably, the mass ratio of the auxiliary component II to the basic molecular sieve carrier is 0.005-0.05:1; Preferably, the basic molecular sieve carrier is selected from at least one of X type, Y type and L type molecular sieves; Preferably, the skeleton charge balance cation of the basic molecular sieve carrier is cesium ion and / or rubidium ion.

3. The method for preparing the catalyst according to any one of claims 1 to 2, characterized in that: The preparation method comprises the following steps: (1) stirring and dissolving a mixture I containing an active component precursor, an auxiliary component I precursor and water to obtain an impregnation solution I; (2) stirring and dissolving a mixture II containing an auxiliary component II precursor and water to obtain an impregnation solution II; (3) impregnating a basic molecular sieve carrier in the impregnation solution I, drying I, calcining I and reducing to obtain a catalyst precursor; (4) impregnating the catalyst precursor in the impregnation solution II, drying II, calcining II to obtain the catalyst.

4. The production method according to claim 3, characterized by, In the step (1), the active component precursor is selected from at least one of chloroiridic acid, sodium chloroiridate and ammonium chloroiridate; Preferably, the auxiliary component I precursor is selected from at least one of chloroauric acid, sodium chloroaurate and potassium chloroaurate; Preferably, in the step (2), the auxiliary component II precursor is selected from at least one of nitrate, hydrochloride and sulfate of zinc, copper, rhenium, cobalt, lanthanum, cerium, titanium, tungsten and nickel elements.

5. The preparation method according to claim 3, characterized in that The mass ratio of the active component precursor to the basic molecular sieve carrier is 0.0005-0.01:1, and the mass of the active component precursor is calculated according to the mass of the active element of the active component; Preferably, the mass ratio of the auxiliary component I precursor to the basic molecular sieve carrier is 0.001-0.02:1, and the mass of the auxiliary component I precursor is calculated according to the mass of the auxiliary element of the auxiliary component I; Preferably, the mass ratio of the auxiliary component II precursor to the basic molecular sieve carrier is 0.005-0.05:1, and the mass of the auxiliary component II precursor is calculated according to the mass of the auxiliary element of the auxiliary component II.

6. The preparation method according to claim 3, characterized in that In the step (3), the temperature of the drying I is 80-150℃, and the time of the drying I is 0.5-20h; Preferably, the temperature of the calcining I is 300-600℃, and the time of the calcining I is 0.5-10h; Preferably, the atmosphere of the reduction is hydrogen; Preferably, the volumetric space velocity of the hydrogen gas is 200 to 500 h -1 ; Preferably, the temperature of the reduction is 200-500℃, and the time of the reduction is 0.5-20h.

7. The preparation method according to claim 3, characterized in that In the step (4), the temperature of the drying II is 80-150°C, and the time of the drying II is 0.5-20h; Preferably, the temperature of the calcination II is 400-600°C, and the time of the calcination II is 0.5-10h.

8. Use of a catalyst according to any one of claims 1 to 2 for the production of n-butane, characterized in that, After the catalyst is pre-reduced by hydrogen, the catalyst is contacted with a raw material containing isobutane and hydrogen to obtain n-butane.

9. Use according to claim 8, characterized in that, The atmosphere of the pre-reduction is hydrogen I; Preferably, the volumetric space velocity of the hydrogen I is 100 to 10000 h -1 ; Preferably, the temperature of the pre-reduction is 350-600°C, and the time of the pre-reduction is 0.2-100h.

10. Use according to claim 8, characterized in that, The feed volume hourly space velocity of the isobutane is 50-10000 h -1 ; Preferably, the molar ratio of the hydrogen to the isobutane is 0.2-10:1; Preferably, the temperature of the contact reaction is 300-500°C, and the pressure of the contact reaction is 0.1-10.0MPa.

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