CN108786861B

CN108786861B - Light alkane isomerization catalyst and preparation method and application thereof

Info

Publication number: CN108786861B
Application number: CN201710305624.8A
Authority: CN
Inventors: 刘洪全; 张秋平; 王京红; 于中伟; 马爱增
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2017-05-03
Filing date: 2017-05-03
Publication date: 2021-03-12
Anticipated expiration: 2037-05-03
Also published as: CN108786861A

Abstract

A light paraffin isomerization catalyst contains gamma-Al₂O₃A carrier and active components with the following content calculated by taking the carrier as a reference: 0.05-1.0 mass% of platinum, 2-12 mass% of chlorine, and gamma-Al₂O₃The carrier is distributed in a double-peak hole mode with large and small holes, the diameter of the largest possible holes of the small holes is 6-10 nm, and the diameter of the largest possible holes of the large holes is 12-20 nm. The catalyst has high isomerization activity and selectivity.

Description

Light alkane isomerization catalyst and preparation method and application thereof

Technical Field

The invention relates to a normal paraffin isomerization catalyst, a preparation method and application thereof, in particular to a light normal paraffin isomerization catalyst, a preparation method and application thereof.

Background

Isomerization of light paraffins generally refers to the isomerization of C₄～C₈The process of converting normal paraffin into isomeric paraffin. The isomerization product of n-butane, i.e. isobutane, is a raw material for important petrochemical processes such as isobutane dehydrogenation, isobutane-butene alkylation, isobutane-propylene co-oxidation and the like. C₅、C₆The octane number of normal paraffin is lower, the octane number of the generated oil obtained after isomerization is obviously improved, and the isomerized generated oil has the characteristics of low sulfur content, no aromatic hydrocarbon and olefin, small difference value (only about 2 units) between the research method octane number and the motor method octane number, low density and the like, is an important blending component of the automobile gasoline, improves the distribution of the octane number of gasoline fractions, improves the front-end octane number of the gasoline, improves the octane number of the automobile, and the likeThe starting performance of (2) plays an important role.

In recent years, along with the continuous acceleration of the upgrading pace of gasoline in China and the rapid development of the petrochemical industry, the importance of light alkane isomerization as a technology for producing clean gasoline blending components and high-quality light hydrocarbon raw materials is increasingly highlighted.

The catalyst is the core of light paraffin isomerization technology, and the existing light paraffin isomerization technology can be divided into medium-temperature molecular sieve isomerization, solid super-strong acid isomerization and low-temperature isomerization according to different catalyst systems. The medium-temperature molecular sieve isomerization takes a Pt or Pd-loaded molecular sieve (usually mordenite or beta molecular sieve) as a catalyst, and the reaction temperature is 240-280 ℃. The solid superacid isomerization is usually carried out by taking Pt-loaded sulfated zirconia as a catalyst and the reaction temperature is 170-210 ℃. The low temperature isomerization is usually carried out by taking Pt-loaded chloridized alumina as a catalyst, and the reaction temperature is 120-200 ℃.

CN201210055961.3 discloses a straight-chain paraffin isomerization catalyst, which comprises a composite macroporous alumina carrier and platinum with the content of 0.01-2.0 mass percent calculated by taking the carrier as a reference, wherein the pore volume of the macroporous alumina is 1.0-1.8 ml/g. The catalyst is prepared by mixing macroporous alumina, chlorine-containing aluminum sol and hydrochloric acid, extruding into strips, and impregnating platinum-carrying with chloroplatinic acid solution.

CN201410295731.3 discloses a normal paraffin isomerization catalyst and a preparation method thereof, wherein the catalyst comprises 0.1-1.0% of metal Pt, 2-5% of element Cl and the balance of gamma-Al₂O₃The catalyst is prepared through impregnating Pt, reducing and adding AlCl₃The inorganic chlorination is carried out by a sublimation method, and then the organic chlorination agent is used for processing.

CN201510502815.4 discloses a normal paraffin low-temperature isomerization catalyst and a preparation method thereof, wherein the catalyst is prepared from 0.1-1.0% of metal Pt, 5.0-10.0% of element Cl and the balance of gamma-Al₂O₃The catalyst adopts a liquid-phase impregnation chlorination mode to introduce chlorine, namely AlCl₃Dipping the reduced Pt/gamma-Al in the organic solution₂O₃And then performing a procedureAnd heating to cure the chlorinating agent. The organic solvent in the organic solution is chloroform and/or ethyl acetate.

Cn201310502862.x discloses a method for preparing a catalyst for isomerization of alkanes, comprising the following steps: the alumina carrier is soaked in solution containing VIII family metal compound, the soaked solid is dried, roasted or treated with water and chlorine, soaked in alkane solution containing alkyl aluminum chloride and dried in the presence of inert gas and in anhydrous condition to obtain the catalyst. The alkyl aluminum chloride used for introducing chlorine by the method has activity , is easy to react with oxygen and trace water, needs to be dried under the conditions of inert gas and no water, and is complex to operate.

Disclosure of Invention

The invention aims to provide a light paraffin isomerization catalyst, a preparation method and application thereof.

The light alkane isomerization catalyst provided by the invention comprises gamma-Al₂O₃A carrier and active components with the following content calculated by taking the carrier as a reference:

0.05 to 1.0 mass% of platinum,

2 to 12% by mass of chlorine,

the gamma-Al₂O₃The carrier is distributed in a double-peak hole mode with large and small holes, the diameter of the largest possible holes of the small holes is 6-10 nm, and the diameter of the largest possible holes of the large holes is 12-20 nm.

The invention uses gamma-Al with bimodal pore distribution₂O₃The catalyst is used for light alkane isomerization reaction, has higher isomerization activity and selectivity, can reduce chlorine loss in the reaction process, and prolongs the one-way service life of the catalyst.

Drawings

FIG. 1 shows gamma-Al prepared in examples of the present invention and comparative examples₂O₃XRD pattern of the support.

FIG. 2 is a view showing γ -Al prepared in example 1 of the present invention₂O₃Pore distribution map of support ZT-1.

FIG. 3 is a pore distribution plot of the catalyst prepared in example 1 of the present invention.

FIG. 4 is a view showing γ -Al prepared in example 2 of the present invention₂O₃Pore distribution map of support ZT-2.

FIG. 5 is a view showing γ -Al prepared in comparative example 1₂O₃Pore distribution map of support ZT-3.

FIG. 6 is a view showing γ -Al prepared in comparative example 2₂O₃Pore distribution map of support ZT-4.

FIG. 7 is a view showing γ -Al prepared in comparative example 3₂O₃Pore distribution map of support ZT-5.

FIG. 8 is a view showing γ -Al prepared in comparative example 4₂O₃Pore distribution map of support ZT-6.

FIG. 9 is a view showing γ -Al prepared in comparative example 5₂O₃Pore distribution map of support ZT-7.

FIG. 10 is a view showing γ -Al prepared in comparative example 6₂O₃Pore distribution map of support ZT-8.

Detailed Description

The invention selects the bimodal gamma-Al with macropore distribution with proper proportion₂O₃The catalyst is prepared by loading active components as a carrier, and the reaction materials can be effectively diffused to the surface of the catalyst under the isomerization reaction condition of low temperature and high airspeed, so that the active center in the catalyst is fully utilized, and the isomerization activity and selectivity are improved. In addition, the method for introducing chlorine into the catalyst is simple, the loss of chlorine in the preparation process of the catalyst is less, the loss of chlorine in the reaction process of the catalyst is correspondingly reduced, and the service life is prolonged.

Gamma-Al as catalyst of the invention₂O₃The carrier has bimodal distribution of small holes and large holes, the diameter of the largest possible hole of the small holes is preferably 6-9.5 nm, and the diameter of the largest possible hole of the large holes is preferably 12-16 nm.

The gamma-Al₂O₃The pore volume of the carrier is preferably 0.60 to 0.8ml/g, more preferably 0.6 to 0.7 ml/g.

The gamma-Al₂O₃In the carrier, the mass ratio of the small-hole alumina to the large-hole alumina is preferably 0.1-10, and more preferably 0.2-5.

The catalyst of the invention preferably has the following active component content:

0.1 to 0.5 mass% of platinum,

4 to 10 mass% of chlorine.

The preparation method of the catalyst provided by the invention comprises the following steps:

(1) uniformly mixing two kinds of pseudo-boehmite powder with most probable pore diameters of 5-7.5 nm and 9-18 nm respectively, adding a peptizing agent aqueous solution, uniformly mixing, forming, drying and roasting to obtain the gamma-Al with bimodal pore distribution₂O₃A carrier, a carrier and a water-soluble polymer,

(2) the gamma-Al prepared in the step (1) is added₂O₃Impregnating carrier with aqueous solution containing platinum compound, drying, roasting, reducing with hydrogen gas to obtain catalyst precursor,

(3) subliming AlCl carried by hydrogen for the catalyst precursor obtained in the step (2)₃Chlorination is carried out at 450-700 ℃.

The step (1) of the method is gamma-Al₂O₃The preparation method of the carrier comprises the steps of uniformly mixing two kinds of pseudo-boehmite powder, wherein the mass ratio of the two kinds of pseudo-boehmite powder is preferably 0.1-10, adding an aqueous solution of a peptizing agent, and uniformly kneading, wherein the peptizing agent is preferably at least one of nitric acid, acetic acid, citric acid, oxalic acid and formic acid, the concentration of an acid-containing aqueous solution is preferably 2-10% by mass, and the mass ratio of the acid-containing aqueous solution to the pseudo-boehmite powder is preferably 0.3-1.0. The shape of the shaped body may be a strip, pellet, tablet, granule or microsphere, preferably a strip, to be suitable for a fixed bed reactor. Drying and roasting the formed material to obtain the gamma-Al₂O₃And (3) a carrier. (1) The roasting temperature is preferably 500-650 ℃.

(1) The pore volume of the pseudo-boehmite powder with the most probable pore diameter of 5-7.5 nm is preferably 0.3-0.5 ml/g, and the pore volume of the pseudo-boehmite powder with the most probable pore diameter of 9-18 nm is preferably 0.54-0.8 ml/g.

The step (2) of the method is a step of preparing a catalyst precursor by supporting platinum on a carrier and carrying out reductionThe platinum-containing compound used for preparing the impregnation liquid is preferably chloroplatinic acid, platinum tetrachloride, ammonium chloroplatinate or dinitrodiammineplatinum. Preferably, the aqueous solution containing the platinum compound further contains a competitive adsorbent, and the competitive adsorbent is selected from one or more of hydrochloric acid, trichloroacetic acid and nitric acid. Quality of impregnating solution and gamma-Al used in impregnating process₂O₃The mass ratio of the carrier is preferably 0.5 to 2.0.

The temperature for drying the impregnated solid is preferably 80-140 ℃, more preferably 100-130 ℃, the drying time is preferably 5-30 h, more preferably 8-24 h, the roasting temperature is preferably 450-650 ℃, more preferably 480-600 ℃, and the roasting time is preferably 1-10 h, more preferably 3-5 h.

The reduction is carried out in hydrogen flow, the volume ratio of gas to agent in the reduction process is preferably 300-1500, the reduction temperature is preferably 400-600 ℃, more preferably 450-580 ℃, and the reduction time is preferably 1-10 hours, more preferably 3-5 hours.

The step (3) of the process is to chlorinate the catalyst precursor to bring the chlorine content to the desired level. The chlorine loading method is to use sublimed AlCl₃The catalyst precursor is treated. The AlCl₃Heating to a sublimation temperature of 178 deg.C or above, and adding H₂Carrying sublimed AlCl as carrier gas₃And contacting the steam with a catalyst precursor for chlorination, wherein the chlorination temperature is preferably 480-650 ℃.

(3) Step (2) using AlCl₃In the chlorination of the catalyst precursor, AlCl₃And the catalyst precursor is preferably 0.05 to 2.0, more preferably 0.1 to 1.5, in mass ratio, and the chlorination time is preferably 0.5 to 2.0 hours.

The volume ratio of the hydrogen to the catalyst precursor gas/agent in the chlorination process is preferably 100-2000, more preferably 200-1000. After the chlorination is finished, H is used₂And blowing the catalyst to reduce the temperature to below 50 ℃.

The catalyst is suitable for isomerization reaction of light alkane, and the method for isomerizing the light alkane by using the catalyst comprises the step of enabling the light alkane to contact and react with the catalyst under the conditions of 100-300 ℃, 2.0-7.0 MPa (absolute pressure) and 0.01-5.0 hydrogen/hydrocarbon molar ratio.

The temperature and the pressure of the isomerization reaction of the light alkane by using the catalyst are preferably 100-200 ℃, the pressure is preferably 2.0-5.0 MPa, the hydrogen/hydrocarbon molar ratio is preferably 0.05-10, and the mass space velocity of the light alkane in contact with the catalyst is 0.5-10.0 hr^-1More preferably 1.0 to 7.0hr^-1。

The light alkane is preferably C₄～C₈Such as n-butane, n-pentane, n-hexane, n-heptane, n-octane, either as pure n-alkanes or as n-alkane-containing materials, such as C-rich materials₅/C₆Reforming topping oil of normal alkane.

The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

The specific surface area and pore volume of the support and catalyst in the examples and comparative examples were measured using a Micromeritics ASAP2400 static nitrogen auto-adsorber. The determination method comprises the following steps: degassing a sample at 300 ℃ and 1.33Pa for 4h, contacting liquid nitrogen with the sample at-196 ℃, statically achieving adsorption balance, calculating specific surface area and pore volume by a BET method according to the volume difference between the nitrogen gas inflow and the nitrogen gas remained in a gas phase after adsorption, and calculating pore size distribution by using a BJH formula.

The Pt content of the catalyst is measured by adopting an Shimadzu UV2401PC ultraviolet-visible spectrophotometer, a sample is firstly dissolved by hydrochloric acid, and then is complexed by stannous chloride, and the Pt content is measured by a colorimetric method.

The Cl content of the catalyst is measured by adopting a Switzerland Vanton potentiometric titrator 905, a sample is firstly dissolved by NaOH to extract chloride ions, and then silver nitrate is used for titration to measure the Cl content.

Example 1

(1) Preparation of gamma-Al₂O₃Carrier

60.0g of pseudo-boehmite powder NB-1 (manufactured by Sasol Corp., alumina content: 75% by mass) and 40.0g of pseudo-boehmite powder NB-2 (manufactured by Sasol Corp., alumina content: 78% by mass) were mixed uniformly, and the specific surface areas and pore volumes of NB-1 and NB-2 were as shown in Table 1. 49.0g of nitric acid water having a concentration of 3% by mass was added to the above powderStirring and kneading the solution evenly, extruding and forming, drying at 120 ℃ for 10h, and roasting at 550 ℃ for 4h to obtain the gamma-Al₂O₃The XRD pattern of ZT-1 on the support is shown in FIG. 1, the specific surface area and the pore volume are shown in Table 2, the pore distribution is shown in FIG. 2, and it can be seen that ZT-1 is bimodal, and the most probable pore diameters are 8.2nm and 15.6nm respectively.

(2) Preparation of catalyst precursor

30.0g of the carrier ZT-1 is taken and added into 30.0g of aqueous solution containing 0.1575g of chloroplatinic acid and 3 mass percent of hydrochloric acid, the mixture is soaked for 1h at 25 ℃, then the water in the solution is evaporated to dryness, the mixture is dried for 12h at 130 ℃, roasted for 4h at 510 ℃, and then reduced for 4h at 500 ℃ by hydrogen, wherein the volume ratio of gas to agent in the reduction is 800, and the catalyst precursor is prepared.

(3) Preparation of the catalyst

With H₂Sublimed AlCl as carrier gas₃The vapors are introduced into a reactor containing 20.0g of catalyst precursor, the catalyst precursor is chlorinated, and AlCl₃The dosage of the (B) is 10.0g, the chlorination temperature is 520 ℃, the chlorination time is 1H, H₂The gas/solvent volume ratio to the catalyst precursor was 600, and the introduction of H was continued after the chlorination had ended₂The temperature was lowered to room temperature to obtain catalyst A whose specific surface area and pore volume are shown in Table 2, pore distribution is shown in FIG. 3, and Pt content and Cl content were 0.25% by mass and 5.6% by mass, respectively, based on the carrier (the same applies hereinafter).

Example 2

A catalyst was prepared by following the procedure of example 1 except that 30.0g of pseudo-boehmite powder NB-3 (manufactured by Sasol Corp., alumina content: 74 mass%) and 70.0g of pseudo-boehmite powder NB-4 (manufactured by Sasol Corp., alumina content: 72 mass%) were uniformly mixed in the step (1), and the specific surface area and pore volume thereof were as shown in Table 1. The gamma-Al is prepared by extruding, drying and roasting₂O₃The specific surface area and pore volume of ZT-2 support are shown in Table 2, the pore distribution is shown in FIG. 4, and the distribution is bimodal, with the most probable pore diameters of 6.6nm and 12.7 nm.

A catalyst B having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst according to the methods in steps (1), (2) and (3) of example 1, taking ZT-2, and having a Pt content of 0.25 mass% and a Cl content of 5.3 mass%.

Example 3

A catalyst was prepared by following the procedure of example 1 except that chloroplatinic acid used in the impregnation solution preparation in the step (2) was 0.0756g, and the catalyst C was obtained to have a Pt content of 0.12 mass% and a Cl content of 5.6 mass%.

Comparative example 1

The catalyst was prepared as in example 1, except that in step (1), only pseudo-boehmite powder NB-1 was used to prepare gamma-Al₂O₃The carrier was prepared into ZT-3, which had a specific surface area and a pore volume as shown in Table 2, a pore distribution as shown in FIG. 5, a monomodal distribution, and a most probable pore diameter of 8.2 nm.

A catalyst D having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst by the methods of steps (1), (2) and (3) of example 1 using ZT-3 as a support, and had a Pt content of 0.25 mass% and a Cl content of 5.8 mass%.

Comparative example 2

The catalyst was prepared as in example 1, except that (1) gamma-Al was prepared from boehmite powder NB-2 alone₂O₃The carrier was prepared into ZT-4, which had a specific surface area and a pore volume as shown in Table 2, a pore distribution as shown in FIG. 6, a monomodal distribution, and a most probable pore diameter of 15.6 nm.

A catalyst E having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst according to the methods in steps (1), (2) and (3) of example 1 from ZT-4, and had a Pt content of 0.25 mass% and a Cl content of 5.3 mass%.

Comparative example 3

The catalyst was prepared as in example 1, except that (1) gamma-Al was prepared from boehmite powder NB-3 alone₂O₃The carrier was prepared into ZT-5, which had a specific surface area and a pore volume as shown in Table 2, a pore distribution as shown in FIG. 7, a monomodal distribution, and a most probable pore diameter of 6.6 nm.

A catalyst F having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst according to the methods of steps (1), (2) and (3) of example 1 from ZT-5, and had a Pt content of 0.25 mass% and a Cl content of 6.0 mass%.

Comparative example 4

The catalyst was prepared as in example 1, except that step (1) was carried out onlyPreparation of gamma-Al from pseudo-boehmite powder NB-4₂O₃The carrier was prepared into ZT-6, which had a specific surface area and a pore volume as shown in Table 2, a pore distribution as shown in FIG. 8, a monomodal distribution, and a most probable pore diameter of 12.7 nm.

A catalyst G having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst according to the methods in steps (1), (2) and (3) of example 1 from ZT-6, and had a Pt content of 0.25 mass% and a Cl content of 5.5 mass%.

Comparative example 5

A catalyst was prepared as in example 1 except that (1) 60.0g of pseudo-boehmite NB-1 and 40.0g of pseudo-boehmite NB-5 (produced by Sasol Co., alumina content: 68 mass%) were mixed in step (1), the specific surface area and pore volume of NB-5 are shown in Table 1, and then the mixture was extruded, dried and calcined to obtain gamma-Al₂O₃The specific surface area and pore volume of ZT-7 support are shown in Table 2, the pore distribution is shown in FIG. 9, the distribution is bimodal, the most probable pore diameters are 8.2nm and 25.5nm, and the most probable pore diameter of the larger pores exceeds the range defined by the present invention.

A catalyst H having a specific surface area and a pore volume as shown in Table 2 was prepared by preparing the catalyst according to the methods of steps (1), (2) and (3) of example 1 from ZT-7, and had a Pt content of 0.25 mass% and a Cl content of 5.3 mass%.

Comparative example 6

The catalyst was prepared as in example 1, except that (1) gamma-Al was prepared from boehmite powder NB-5 alone₂O₃The carrier is extruded, dried and roasted to obtain the carrier ZT-8, the specific surface area and the pore volume of the carrier are shown in a table 2, the pore distribution is shown in a figure 10 and is in unimodal distribution, and the diameter of most probable pores is 25.5 nm.

A catalyst was prepared by the methods of step (2) and step (3) of example 1 using ZT-8 as a support to obtain catalyst I, whose specific surface area and pore volume are shown in Table 2, whose Pt content was 0.25 mass% and Cl content was 4.8 mass%.

Comparative example 7

A catalyst was prepared by taking 30.0g of the carrier ZT-3 and following the procedures in (1), (2) and (3) except that 0.0756g of chloroplatinic acid was used for preparing the impregnation liquid in the step (2), and the catalyst J was obtained so that the Pt content was 0.12% by mass and the Cl content was 5.8% by mass, and the specific surface area and the pore volume thereof were as shown in Table 2.

Comparative example 8

A catalyst was prepared by the method of steps (3) and (2) of example 1, except that 0.0756g of chloroplatinic acid was used for the preparation of the impregnation solution in step (2), and that the catalyst K was prepared so as to have a Pt content of 0.12 mass% and a Cl content of 5.3 mass%, and the specific surface area and pore volume thereof were as shown in Table 2.

Examples 4 to 14

The following examples examine catalyst C₅/C₆Isomerization reaction performance.

The catalyst of the present invention and the comparative catalyst were evaluated on a small fixed bed reaction apparatus using as a raw material a mixed hydrocarbon having an n-pentane content of 10 mass% and an n-hexane content of 90 mass%, under the evaluation conditions: the reaction temperature is 130 ℃, the reaction pressure (gauge pressure) is 3.0MPa, and the feed mass space velocity is 1.5hr^-10.25 hydrogen/hydrocarbon molar ratio and 10h reaction time, the average result of 10h being shown in Table 3.

In Table 3

C₅Isomerization ratio (mass of isopentane in product/C in product)₅Mass of alkane) × 100%;

C₆isomerization ratio (1- (mass of n-hexane in product/C in product)₆Mass of alkane)) × 100%;

C₆selectivity (mass of 2, 2-dimethylbutane in product/C in product)₆The mass of the alkane) × 100%

As can be seen from Table 3, the catalyst of the present invention has a higher C than the comparative catalyst₅Isomerization ratio, C₆Isomerization ratio and C₆And (4) selectivity.

Examples 15 to 18

The following examples examine the n-butane isomerization reaction performance of the catalyst.

In the purity of>99.8% by mass of n-butane as a reaction raw material, the catalyst of the present invention and the comparative catalyst were evaluated on a small fixed bed reactor under the following conditions: 170 deg.C, 3.0MPa, and feeding mass air speed of 4.0hr^-1The hydrogen/hydrocarbon molar ratio was 0.05, the reaction time was 5h, and the results are given in Table 4, taking the average of 5 h.

In Table 4

N-butane conversion ═(mass of n-butane in the raw material-mass of n-butane in the product)/mass of n-butane in the raw material) × 100%;

isobutane selectivity (mass of isobutane in product/(mass of n-butane in raw material-mass of n-butane in product)) × 100%

As can be seen from Table 4, the catalyst of the present invention has higher n-butane conversion and isobutane selectivity than the comparative catalyst.

Example 19

This example examines C for catalyst A of the invention and catalyst D prepared in comparative example 1₅/C₆And (3) isomerization reaction stability.

A mixed hydrocarbon containing 10 mass% of n-pentane and 90 mass% of n-hexane was used as a raw material, and the catalyst was evaluated in a small fixed bed reactor under the following conditions: the reaction temperature is 130 ℃, the reaction pressure (gauge pressure) is 3.0MPa, and the feed mass space velocity is 1.5hr^-1Hydrogen/hydrocarbon molar ratio of 0.25, continuously reacting for 800 hours under the condition, analyzing the product composition on line every 2 hours in the reaction process, and obtaining C₅Isomerization ratio, C₆Isomerization ratio and C₆The selectivity and results are shown in Table 5.

As can be seen from Table 5, catalyst A of the present invention has higher stability than comparative catalyst D.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

TABLE 5

Claims

1. A light paraffin isomerization catalyst contains gamma-Al₂O₃A carrier and active components with the following content calculated by taking the carrier as a reference:

0.05 to 1.0 mass% of platinum,

2 to 12% by mass of chlorine,

2. The catalyst of claim 1, wherein said γ -Al is₂O₃The diameter of the largest possible few pores of the small pores of the carrier is 6-9.5 nm, and the diameter of the largest possible few pores of the large pores is 12-16 nm.

3. Catalyst according to claim 1 or 2, characterized in that the γ -Al is₂O₃The pore volume of the carrier is 0.60-0.80 ml/g.

4. Catalyst according to claim 1 or 2, characterized in that the γ -Al is₂O₃In the carrier, the mass ratio of the small holes to the large-hole alumina is 0.1-10.

5. The catalyst according to claim 1 or 2, characterized in that the active component content is:

0.1 to 0.5 mass% of platinum,

4 to 10 mass% of chlorine.

6. A method of preparing the catalyst of claim 1, comprising the steps of:

7. The method according to claim 6, wherein the calcination temperature in step (1) is 500 to 650 ℃.

8. The method according to claim 6, wherein the pore volume of the pseudo-boehmite powder with the most probable pore diameter of 5 to 7.5nm in step (1) is 0.3 to 0.5ml/g, and the pore volume of the pseudo-boehmite powder with the most probable pore diameter of 9 to 18nm is 0.54 to 0.8 ml/g.

9. The method according to claim 6, wherein the mass ratio of the two kinds of pseudo-boehmite powder in the step (1) is 0.1-10, and the forming method is extrusion molding.

10. The method according to claim 6, wherein the peptizing agent in step (1) is at least one selected from the group consisting of nitric acid, acetic acid, citric acid, oxalic acid and formic acid.

11. The method according to claim 6, wherein the platinum-containing compound in step (2) is chloroplatinic acid, platinum tetrachloride, ammonium chloroplatinate or dinitrosoplatinum.

12. The method according to claim 6, wherein the aqueous solution containing platinum compound in step (2) further contains a competitive adsorbent, wherein the competitive adsorbent is selected from one or more of hydrochloric acid, trichloroacetic acid and nitric acid.

13. The method of claim 6, wherein step (3) uses AlCl₃In the chlorination of the catalyst precursor, AlCl₃And the catalyst precursor is 0.05-2.0 by mass, and the chlorination time is 0.5-2.0 hours.

14. A light alkane isomerization method, which comprises the step of contacting and reacting light alkane with the catalyst of claim 1 under the conditions of 100-300 ℃, 2.0-5.0 MPa and hydrogen/hydrocarbon molar ratio of 0.01-5.0.

15. The method of claim 14, wherein the light alkane is contacted with the catalyst at a mass space velocity of 0.5 to 10.0hr^-1。

16. The process of claim 14, wherein the light alkane is C₄～C₈Of (a) an alkane.