CN114075452B - Isomerization method of linear olefins - Google Patents

Abstract

The invention relates to the field of isomerization of high-carbon linear olefins, and discloses a method for isomerization of linear olefins. Including: in the presence of hydrogen and/or inert gas, C ₄ ‑C ₂₀ linear olefins or Fischer-Tropsch light oil containing C ₄ ‑C ₂₀ linear olefins are contacted with a catalyst containing ZSM‑48 molecular sieve for isomerization reaction to obtain a product containing C ₄ -C ₂₀ isomerized olefins. It can realize the isomerization of C ₈ and above linear olefins, can satisfy the isomerization processing of high carbon number linear olefins, and has good isomerization activity and selectivity for C ₄ ‑C ₂₀ linear olefins.

Description

Isomerization method of linear olefins

technical field

The invention relates to the field of isomerization of linear olefins, in particular to a method for isomerizing linear olefins.

Background technique

In petroleum cracking components, it often contains straight-chain olefins with short carbon chains (C ₄ -C ₇ ), and its application range is narrow. However, if skeletal isomerization is carried out, on the one hand, it can be directly used as an additive to improve the octane number of gasoline components, and on the other hand, it can be used as a raw material for the production of alkyl ethers (such as methyl tert-butyl ether). Alkyl ethers are very good octane components, so how to isomerize linear olefins to isomeric olefins has received a lot of attention.

CN1317466A discloses a method for structurally isomerizing linear olefins having at least 4 carbon atoms into their corresponding methyl-branched isoolefins, comprising, at a temperature of about 200°C to about 650°C, making A hydrocarbon feedstream containing at least one said linear olefin is contacted with an isomerization catalyst prepared by a process comprising: (a) mixing (i) a zeolite powder comprising at least one zeolite, the zeolite Having at least one one-dimensional pore structure, the pore size is small enough to prevent dimerization of by-products and coke formation, and large enough to allow the entry of linear olefins and the formation of methyl-branched iso-olefins, ( ii) an alumina-containing binder, (iii) water, and (iv) an effective amount of an acid comprising at least one polycarboxylic acid that peptizes the zeolite powder, the binder, or a mixture thereof, thereby producing into a mixture; (b) forming said mixture into one or more solid particles, and (c) calcining said particles at a temperature of from about 200°C to about 700°C. Among them, the molecular sieves are ZSM-22 and ZSM-23, and the binder is alumina and polycarboxylic acid. The catalyst is mainly aimed at the isomerization reaction of linear butene and pentene.

CN101376617A discloses a method for skeletal isomerization of olefins, comprising contacting olefin-containing raw material oil with a catalyst containing β molecular sieves under olefin skeletal isomerization reaction conditions, wherein the β molecular sieves contain magnesium, calculated as oxides And based on the total amount of molecular sieves, the content of the magnesium is 0.1-3.5% by weight.

CN108114735A discloses a method for preparing a catalyst for skeletal isomerization of linear olefins. The specific synthesis steps are as follows: (1) Treat the synthesized FER molecular sieve with HF/NH ₄ F solution at 30-90°C for 0.1-10 hours; (2) washing the product of step (1) to neutrality, extruding and extruding, exchanging and filtering with ammonium nitrate solution, and washing with deionized water, drying, roasting; The isomerization catalyst is prepared by treating with water vapor at -700°C for 1-8 hours. For the preparation of isobutene.

CN103102235A discloses a method for isomerizing n-butene to prepare isobutene and co-produce high-octane gasoline, comprising: step A, carbon four components rich in n-butene are superimposed under the action of an acidic catalyst , cyclization, isomerization, hydrogen transfer, alkylation, and dehydrogenation reactions to produce high-octane gasoline components containing C ₈ isomeric olefins and aromatics; step B, carbon four groups rich in n-butene A selective skeletal isomerization reaction occurs under the action of an acidic catalyst to generate isobutene; wherein, the reaction temperature of step A is 200-300°C, and the reaction temperature of step B is 300-350°C. It mainly describes the preparation method of the heterogeneous catalyst containing ZSM-35 molecular sieve, and is applied to the preparation of isobutene.

CN106076408A discloses a catalyst for isomerization of normal olefins, which contains 50-90% (mass) of molecular sieves, and the rest is alumina; the molecular sieves are composed of SAPO-11 and ZSM-5, wherein SAPO-11 accounts for the total amount of molecular sieves 75-90% (mass) of the molecular sieve, and ZSM-5 accounts for 10-25% (mass) of the total molecular sieve. Applied to the preparation of isobutene.

CN103301876A discloses a method for preparing a catalyst for skeletal isomerization of linear olefins. The specific synthesis steps are as follows: (1) Treat the synthesized rare earth ZSM-35 molecular sieve with an alkali solution at 30-90° C. for 0.5-10 hours; ( 2) Wash the product of step (1) until it is neutral, extrude it, exchange it with ammonium nitrate solution, filter it, wash it with deionized water, dry it, and roast it; The isomerization catalyst is prepared by treating with water vapor at 700° C. for 1-8 hours.

值为5以下，所述/>

值采用以下方法测定：将10g所述组合物在120℃于空气气氛中干燥240分钟，将经干燥的组合物的质量记为w₁，采用式I计算/>

值，/>

(式I)。CN107999141A discloses a hydrated alumina composition containing ZSM-48 molecular sieve, the composition contains hydrated alumina, ZSM-48 molecular sieve and a compound with at least two proton acceptor sites, the composition

value of 5 or less, the />

The value is determined by the following method: 10 g of the composition is dried in an air atmosphere at 120° C. for 240 minutes, and the mass of the dried composition is recorded as w ₁ , calculated using formula I

value, />

(Formula I).

CN109701606A discloses a skeleton isomerization catalyst, which comprises the following components in weight percent: (1) 95.5-100% molecular sieve containing ten-membered ring structure; (2) 0-4.5% binder.

However, the prior art mostly deals with raw materials from petroleum refining, and the straight-chain olefins contained in the raw materials have a small number of carbon atoms. Due to the short chain length of low-carbon olefins, cracking is not easy to occur, and the difficulty of skeletal isomerization is low. Most of the catalysts used are Pt/molecular sieve systems.

In the field of Fischer-Tropsch synthetic oil, the iron-based Fischer-Tropsch synthetic light oil component (C ₄ -C ₂₀ ) (Fischer-Tropsch light oil) contains a large amount of high-carbon number (above C ₈ ) linear terminal olefins, and the content can reach 60 wt. %above. In the existing process, the processing of this component is often subjected to hydrogenation saturation, followed by cracking, isomerization or cracking to obtain low-carbon olefins. Not only the production process is long, but the processing cost is increased, and the high-carbon number components are destroyed, wasting raw materials resource. Therefore, it is necessary to provide an isomerization method suitable for high-carbon olefins according to the composition characteristics of Fischer-Tropsch light oil.

Contents of the invention

The object of the present invention is to provide a method for isomerizing linear olefins in order to overcome the problem of how to achieve better isomerization of high-carbon linear olefins contained in Fischer-Tropsch light oil. Especially in order to realize the isomerization of the linear olefins with a high carbon number above _C8 contained in the light oil component obtained by Fischer-Tropsch synthesis to obtain isomerized olefins with a high carbon number. This method can also realize the isomerization of C ₄ -C ₇ linear olefins.

In order to achieve the above object, the present invention provides a method for isomerizing linear olefins, comprising: in the presence of hydrogen and/or inert gas, C ₄ -C ₂₀ linear olefins or C ₄ -C ₂₀ linear olefins The Fischer-Tropsch light oil is contacted with a catalyst containing ZSM-48 molecular sieve for isomerization reaction to obtain a product containing C ₄ -C ₂₀ isomeric olefins.

Preferably, in the Fischer-Tropsch light oil, the content of linear olefins above _C8 is 60-80% by weight.

Preferably, the catalyst containing ZSM-48 molecular sieve is prepared by the following method:

(1) ZSM-48 molecular sieve is mixed with lye, and then water is added for beating to obtain mixed slurry, which is then filtered, washed and dried to obtain modified ZSM-48 molecular sieve;

(2) Mixing the modified ZSM-48 molecular sieve, aluminum binder and water, then adding an acid solution for kneading, and then extruding to obtain a catalyst precursor;

(3) The catalyst precursor is subjected to hydrothermal treatment, washing with a mixed solution containing ammonium salt and acid and water washing in sequence, and then drying to obtain the catalyst.

Through the above technical scheme, the method provided by the present invention can realize that the Fischer-Tropsch light oil rich in C ₄ -C ₂₀ linear olefins (the content of linear olefins above C ₈ can reach more than 60% by weight) directly passes through the ZSM-48 molecular sieve The catalyst isomerized to obtain isomeric olefins. In particular, it can realize the isomerization of linear olefins above C ₈ contained in the material, and can meet the isomerization processing of high-carbon linear olefins. It has good isomerization activity and selectivity for Fischer-Tropsch light oil. The constitutive selectivity can reach more than 94%.

Detailed ways

Neither the endpoints nor any values of the ranges disclosed herein are limited to such precise ranges or values, and these ranges or values are understood to include values approaching these ranges or values. For numerical ranges, between the endpoints of each range, between the endpoints of each range and individual point values, and between individual point values can be combined with each other to obtain one or more new numerical ranges, these values Ranges should be considered as specifically disclosed herein.

The invention provides a method for isomerizing linear olefins, comprising: in the presence of hydrogen and/or inert gas, C ₄ -C ₂₀ linear olefins or Fischer-Tropsch light oil containing C ₄ -C ₂₀ linear olefins It is contacted with a catalyst containing ZSM-48 molecular sieve to carry out isomerization reaction to obtain a product containing C ₄ -C ₂₀ isomeric olefins.

The present invention particularly relates to the isomerization of materials containing high-carbon linear olefins, such as light oil components obtained from Fischer-Tropsch synthesis. Olefins above C ₈ are very easy to induce cracking reaction on the acidic site of the catalyst, so not only is it difficult to maintain the skeleton but isomerize and break the chain, but also the excessive cracking reaction will also bring about problems such as coking, which will lead to unstable catalyst performance and loss of catalyst performance. Lively. Therefore the present invention carries out the straight-chain olefins contained in the light oil component obtained by Fischer-Tropsch synthesis (which contains high-carbon straight-chain olefins, such as C ₈ or more straight-chain olefins whose content can reach up to 80% by weight), and carry out one-step direct Isomerization into isomeric olefins can provide isomeric olefin products with high carbon number compared with the existing technology, and realize the production of isomerized products from light oil components obtained by Fischer-Tropsch synthesis. More preferably, the linear olefins above C ₈ are terminal olefins, that is, α-olefins. Preferably, in the Fischer-Tropsch light oil, the content of linear olefins above _C8 reaches 60-80% by weight.

In some embodiments of the present invention, limiting the conditions of the isomerization reaction enables the catalyst to perform a better catalytic function, which is beneficial to the isomerization. Preferably, the conditions of the isomerization reaction include: a temperature of 100-400° C.; a pressure of 0-3 MPa; a weight ratio of hydrogen and/or inert gas to C ₄ -C ₂₀ linear olefins not greater than 0.2; C ₄ The weight hourly space velocity of -C ₂₀ linear olefin is 0.5-5h ^-1 . More preferably, the temperature is 200-300°C; the pressure is 0-0.5MPa; the weight ratio of hydrogen and/or inert gas to C ₄ -C ₂₀ linear olefins is 0.01-0.05; the weight ratio of C ₄ -C ₂₀ linear olefins The weight hourly space velocity is 1-2h ^-1 .

In some embodiments of the present invention, the isomerization method can be performed in the presence of an inert gas, preferably, the inert gas includes nitrogen, argon or helium, preferably the inert gas is nitrogen.

In some embodiments of the present invention, the catalyst preparation method used is provided, and the obtained catalyst is beneficial to realize the object of the present invention. Preferably, the catalyst containing ZSM-48 molecular sieve is prepared by the following method:

(1) ZSM-48 molecular sieve is mixed with lye, and then water is added for beating to obtain mixed slurry, which is then filtered, washed and dried to obtain modified ZSM-48 molecular sieve;

(2) Mixing the modified ZSM-48 molecular sieve, aluminum binder and water, then adding an acid solution for kneading, and then extruding to obtain a catalyst precursor;

(3) The catalyst precursor is subjected to hydrothermal treatment, washing with a mixed solution containing ammonium salt and acid and water washing in sequence, and then drying to obtain the catalyst.

In some embodiments of the present invention, ZSM-48 molecular sieves are selected to provide the desired reactivity and selectivity to isomerize reactants in the isomerization reaction. Preferably, in step (1), the molar ratio of SiO ₂ /Al ₂ O ₃ (silicon-aluminum ratio) of the ZSM-48 molecular sieve is 50-200, preferably 60-150. The use of ZSM-48 molecular sieve with this silicon-aluminum ratio can provide high activity for isomerization of long-chain linear olefins, and the reaction temperature requirement is low.

In some embodiments of the present invention, step (1) is used to modify the ZSM-48 molecular sieve to adjust the acidic properties of the molecular sieve. Preferably, the lye is a solution of ammonia, Na ₂ CO ₃ or NaOH. In some embodiments of the present invention, preferably, the concentration of the lye is 0.01-0.2M, preferably 0.05-0.1M. The silicon-aluminum ratio of the local framework of the molecular sieve can be adjusted. Further, the dosage of the lye is regulated to meet the requirement of increasing the proportion of the molecular sieve skeleton strong acid in the total acid, improving the reactivity and isomerization selectivity.

In some embodiments of the present invention, preferably, the mass ratio of water:ZSM-48 molecular sieve is (1-20):1, preferably (2-5):1.

In some embodiments of the present invention, preferably, the beating temperature is 25-80°C, preferably 40-60°C; the beating time is 0.5-24h, preferably 1-3h.

In some embodiments of the present invention, preferably, in step (2), the aluminum binder is selected from at least one of pseudoboehmite, aluminum sol, aluminum hydroxide dry glue and boehmite .

In some embodiments of the present invention, preferably, the aluminum binder is based on Al ₂ O ₃ dry basis, and the weight ratio of the modified ZSM-48 molecular sieve to the aluminum binder (dry basis) is 0.1-4, preferably 1-3. In the isomerization method provided by the present invention, the amount of the ZSM-48 molecular sieve can also satisfy that the weight ratio of the ZSM-48 molecular sieve to the total amount of the catalyst is 0.1-0.8.

In some embodiments of the present invention, preferably, the acid solution is at least one of nitric acid solution and/or phosphoric acid. Preferably, the acid solution has a concentration of 1-10 wt%.

In some embodiments of the present invention, preferably, the acid solution can assist in peptization, kneading and shaping of the catalyst precursor. The consumption of described acid solution can be metered with the weight ratio of the acid in the acid solution and the dry basis powder (the sum of the modified ZSM-48 molecular sieve and the aluminum binder), preferably, the acid and the dry basis powder The weight ratio of the body is 0.01-0.05; the weight ratio of the total amount of water contained in the acid solution and the water added in step (2) to the dry powder is 0.5-0.8.

In some embodiments of the present invention, preferably, in step (3), the conditions of the hydrothermal treatment include: using nitrogen as a carrier gas, continuously passing water to the catalyst precursor for treatment, and the hydrothermal treatment temperature is 200- 500°C, preferably 300-400°C; the hydrothermal treatment time is 0.5-6h.

In some embodiments of the present invention, preferably, relative to 100 g of the catalyst precursor, the water flow rate is 10-50 mL/h.

In some embodiments of the present invention, preferably, in step (3), in the mixed solution, the concentration of the ammonium salt is 0.05-0.5M, preferably 0.1-0.2M, and the concentration of the acid is 0.05 -0.5M, preferably 0.1-0.2M.

In some embodiments of the present invention, preferably, the washing temperature of the mixed solution is 40-90°C, preferably 60-80°C, and the washing time of the mixed solution is 0.1-5h, preferably 0.5-1h.

In some embodiments of the present invention, preferably, the ammonium salt is at least one of ammonium sulfate, ammonium chloride, and ammonium nitrate, preferably ammonium sulfate; the acid is at least one of sulfuric acid, hydrochloric acid, and nitric acid species, preferably sulfuric acid. The washing with the mixed solution containing ammonium salt and acid can remove Na ions that may remain in the catalyst precursor.

In some embodiments of the present invention, preferably, the washing with water includes: washing with deionized water and filtering until the obtained filtrate has a pH value of 7-8.

In some embodiments of the present invention, the filter cake obtained by filtering is dried. Preferably, the drying temperature is 100-120° C. and the drying time is 12-24 hours.

In some embodiments of the present invention, preferably, the specific surface area of the catalyst is 200-300m ² /g, and the pore volume is 0.4-0.8cm ³ /g; the total acid content of the catalyst is not less than 65 μmol by pyridine infrared analysis /g, the proportion of strong acid is greater than 60%. The acidity was determined according to "Pyridine-thermal desorption-infrared method to determine catalyst acidity" (Liu Xiaosa et al., Industrial Catalysts, 2015 (10)).

In the present invention, all pressures involved are gauge pressures.

The present invention will be described in detail below by way of examples. In the following examples, the content and types of isomer products were obtained through Agilent 7890A chromatographic analysis.

Butene was produced by Helium Spectrum North Branch, and decene and hexadecene were produced by Aladdin reagent.

Preparation Example 1

1) Take 200g of ZSM-48 (silicon-aluminum ratio 80), disperse it into 600g NaOH solution with a concentration of 0.1M (the mass ratio of water to ZSM-48 is about 3:1), stir vigorously until the dispersion is uniform, and heat up to 40°C And keep the temperature for 2 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 75g of modified ZSM-48 molecular sieve, mix with 34.7g of pseudoboehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo The weight ratio of boehmite is 3:1), while stirring in the kneader, slowly add 60g dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry base powder is 0.03), wherein the total water content ( The weight ratio of the amount of water added (the sum of the amount of water in the dilute nitric acid solution) to the dry powder is 60, after stirring evenly, it is extruded with an extruder to obtain the initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a flow rate of 20mL/h, heat up to 300°C and keep the temperature constant for 2h for hydrothermal treatment; then get The sample was heated to 80°C with a 0.1M (ammonium sulfate + sulfuric acid) mixed solution and washed at a constant temperature for 1 hour; then washed with deionized water, filtered until the pH value of the obtained filtrate was 7, and finally dried to obtain catalyst A.

Preparation example 2

1) Take 200g of ZSM-48 (silicon-aluminum ratio 60), disperse it into 400g NaOH solution with a concentration of 0.05M (the mass ratio of water to ZSM-48 is about 2:1), stir vigorously until the dispersion is uniform, and heat up to 50°C And keep the temperature for 1h, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 75g of modified ZSM-48 molecular sieve and 34.7g of pseudoboehmite (according to Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water and mix evenly (modified ZSM-48 molecular sieve: pseudo thin The weight ratio of diaspore is 3:1), while stirring in the kneader, slowly add 60g dilute phosphoric acid solution (containing phosphoric acid 5g, the weight ratio of acid to dry basis powder is 0.05), wherein, the total water content and dry The weight ratio of the base powder is 50, and after being uniformly stirred, it is extruded with a bar extruder to obtain an initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a water flow rate of 50mL/h, heat up to 360°C and keep the temperature constant for 6h for hydrothermal treatment; then get The sample was heated to 60°C with a 0.2M (ammonium chloride + hydrochloric acid) mixed solution and washed at a constant temperature for 0.7h; then washed with deionized water, filtered until the pH of the obtained filtrate was 8, and finally dried to obtain Catalyst B .

Preparation example 3

1) Take 200g of ZSM-48 (silicon-aluminum ratio 150), disperse it into 1000g NaOH solution with a concentration of 0.08M (the mass ratio of water to ZSM-48 is about 5:1), stir vigorously until the dispersion is uniform, and heat up to 60°C And keep the temperature for 3 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 75g of modified ZSM-48 molecular sieve, mix with 34.7g of pseudoboehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo The weight ratio of boehmite is 3:1), while stirring in the kneader, slowly add 80g dilute nitric acid solution (containing nitric acid 1g, the weight ratio of acid to dry base powder is 0.01), wherein the total water content ( The weight ratio of the amount of water added (the sum of the amount of water in the dilute nitric acid solution) to the dry base powder is 80, and after being stirred evenly, it is extruded with an extruder to obtain an initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, and under the action of carrier gas, pass in deionized water with a flow rate of 80mL/h, heat up to 400°C and keep the temperature constant for 0.5h for hydrothermal treatment; then The obtained sample was heated to 70°C with a 0.16M (ammonium nitrate + nitric acid) mixed solution and washed at a constant temperature for 0.5h; then washed with deionized water, filtered until the pH of the obtained filtrate was 7.5, and finally dried to obtain catalyst C .

Preparation Example 4

1) Take 200g of ZSM-48 (silicon-aluminum ratio 80), disperse it into 600g NaOH solution with a concentration of 0.1M (the mass ratio of water to ZSM-48 is about 3:1), stir vigorously until the dispersion is uniform, and heat up to 40°C And keep the temperature for 2 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 50g of modified ZSM-48 molecular sieve, mix with 69.4g of pseudoboehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo The weight ratio of boehmite is 1:1), while stirring in the kneader, slowly add 60g dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry base powder is 0.03), wherein the total water content ( The weight ratio of the amount of water added (the sum of the amount of water in the dilute nitric acid solution) to the dry powder is 60, after stirring evenly, it is extruded with an extruder to obtain the initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a flow rate of 20mL/h, heat up to 300°C and keep the temperature constant for 2h for hydrothermal treatment; then get The sample was heated to 80°C with a 0.1M (ammonium sulfate + sulfuric acid) mixed solution and washed at a constant temperature for 1 hour; then washed with deionized water, filtered until the pH of the obtained filtrate was 7, and finally dried to obtain catalyst D.

Preparation Example 5

1) Take 200g of ZSM-48 (silicon-aluminum ratio 200), disperse it into 600g NaOH solution with a concentration of 0.1M (the mass ratio of water to ZSM-48 is about 3:1), stir vigorously until the dispersion is uniform, and heat up to 40°C And keep the temperature for 2 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 60g of modified ZSM-48 molecular sieve, mix with 55.6g of pseudo-boehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo-boehmite: The weight ratio of boehmite is 1.5:1), while stirring in the kneader, slowly add 60g dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry base powder is 0.03), wherein the total water content ( The weight ratio of the amount of water added (the sum of the amount of water in the dilute nitric acid solution) to the dry powder is 60, after stirring evenly, it is extruded with an extruder to obtain the initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a flow rate of 20mL/h, heat up to 300°C and keep the temperature constant for 2h for hydrothermal treatment; then get The sample was heated to 80°C with a 0.1M (ammonium sulfate + sulfuric acid) mixed solution and washed at a constant temperature for 1 hour; then washed with deionized water, filtered until the pH value of the obtained filtrate was 7, and finally dried to obtain catalyst E.

Prepare comparative example 1

Take 75g of ZSM-48 molecular sieve (silicon-aluminum ratio ₈₀ ) and 34.7g of pseudo-boehmite (according to _Al2O3 dry basis, _{Al2O3 content} 72%) and water and mix evenly (modified ZSM-48 molecular sieve: The weight ratio of pseudo-boehmite is 3:1), while stirring in the kneader, slowly add 60g of dilute nitric acid solution (containing 3g of nitric acid, and the weight ratio of acid to dry powder is 0.03), wherein the total water The weight ratio to the dry base powder is 60. After stirring evenly, it is extruded with an extruder to obtain the catalyst DB-1.

Prepare comparative example 2

1) Take 200g of ZSM-48 (silicon-aluminum ratio 80), disperse it into 600g NaOH solution with a concentration of 0.1M (the mass ratio of water to ZSM-48 is about 3:1), stir vigorously until the dispersion is uniform, and heat up to 40°C And keep the temperature for 2 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-48 molecular sieve;

2) Take 75g of modified ZSM-48 molecular sieve, mix with 34.7g of pseudoboehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo The weight ratio of boehmite is 3:1), while stirring in the kneader, slowly add 60g of dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry base powder is 0.03), wherein the total water content and The weight ratio of the powder on a dry basis is 60. After being evenly stirred, it is extruded with an extruder to obtain catalyst DB-2.

Prepare comparative example 3

1) Take 75g of ZSM-48 molecular sieve (silicon-alumina ratio 80), mix it with 34.7g pseudo-boehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM- 48 molecular sieves: the weight ratio of pseudo-boehmite is 3:1), while stirring in the kneader, slowly add 60g dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry powder is 0.03), wherein , the weight ratio of the total amount of water to the dry base powder is 60, after stirring evenly, extrude molding with an extruder to obtain the initial sample of the strip catalyst;

2) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a water flow rate of 20mL/h, heat up to 300°C and keep the temperature constant for 2h for hydrothermal treatment; then get The sample was heated to 80°C with a 0.1M (ammonium sulfate + sulfuric acid) mixed solution and washed at a constant temperature for 1 hour; then washed with deionized water, filtered until the pH value of the obtained filtrate was 7, and finally dried to obtain catalyst DB-3 .

Prepare comparative example 4

1) Take 200g of ZSM-35 (silicon-aluminum ratio 80), disperse it into 600g of NaOH solution with a concentration of 0.1M (the mass ratio of water to ZSM-48 is about 3:1), stir vigorously until the dispersion is uniform, and heat up to 40°C And keep the temperature for 2 hours, filter and wash until the pH value of the filtrate is less than 10, and dry the filter cake at 120°C to obtain a modified ZSM-35 molecular sieve;

2) Take 75g of modified ZSM-35 molecular sieve, mix with 34.7g of pseudoboehmite (based on Al ₂ O ₃ dry basis, Al ₂ O ₃ content 72%) and water (modified ZSM-48 molecular sieve: pseudo The weight ratio of boehmite is 3:1), while stirring in the kneader, slowly add 60g dilute nitric acid solution (containing nitric acid 3g, the weight ratio of acid to dry base powder is 0.01), wherein the total water content ( The weight ratio of the amount of water added (the sum of the amount of water in the dilute nitric acid solution) to the dry powder is 60, after stirring evenly, it is extruded with an extruder to obtain the initial sample of the bar-shaped catalyst.

3) Put 100g of bar-shaped catalyst sample into a hydrothermal tube furnace, under the action of carrier gas, pass through deionized water with a flow rate of 20mL/h, heat up to 300°C and keep the temperature constant for 2h for hydrothermal treatment; then get The sample was heated to 80°C with a 0.1M (ammonium sulfate + sulfuric acid) mixed solution and washed at a constant temperature for 1 hour; then washed with deionized water, filtered until the pH value of the obtained filtrate was 7, and finally dried to obtain the catalyst DB-4 .

Catalysts A-E, DB-1 to DB-4 were tested and characterized for specific surface area, pore volume and acidity, and the results are shown in Table 1. Specific surface area and pore volume were measured by nitrogen adsorption-desorption isotherm method; acidity was analyzed by pyridine adsorption-desorption infrared. In the acidity test results, the percentage of strong acid refers to the strong acid value (350°C pyridine desorption treatment)/total acid value (200°C pyridine desorption treatment)×100%.

Table 1

Example 1

Butene isomerization evaluations were carried out with catalysts A-E, DB-1 to DB-4, respectively.

In a fixed bed reactor, 2.0g of catalyst is installed, the carrier gas is hydrogen, the flow rate of hydrogen is 50mL/min, the weight hourly space velocity of butene feed is 1.5h ^-1 , the reaction temperature is 300°C, and the reaction pressure is 0.1MPa, The weight ratio of hydrogen to butene was 0.05. The continuous reaction was carried out for about 100 h, and the analysis results of the isomeric products are shown in Table 2.

Table 2

catalyst Conversion rate,% Isobutene yield, % Isomer selectivity, % A 45.3 44.2 97.6 B 43.3 41.6 96.1 C 47.1 45.7 97.0 D. 40.5 38.7 95.6 E. 41.2 39.9 96.8 DB-1 30.0 26.5 88.3 DB-2 33.8 29.9 88.5 DB-3 36.8 33.1 89.9 DB-4 38.5 30.4 79.0

Example 2

The evaluation of decene isomerization was carried out with catalysts A-E, DB-1 to DB-4 respectively.

In a fixed-bed reactor, 2.0 g of catalyst was installed, the carrier gas was hydrogen, the flow rate of hydrogen was 50 mL/min, the weight hourly space velocity of decene feed was 2 h ^-1 , the reaction temperature was 200 ° C, and the reaction pressure was 0.3 MPa. The weight ratio of ene was 0.03. The continuous reaction was carried out for about 100 h, and the analysis results of the isomeric products are shown in Table 3.

table 3

catalyst Conversion rate,% Isodecene yield, % Isomer selectivity, % A 50.5 48.9 96.8 B 51.2 49.2 96.1 C 51.8 49.3 95.2 D. 44.6 42.7 95.7 E. 47.4 45.1 95.1 DB-1 38.2 34.4 90.1 DB-2 39.0 34.9 89.5 DB-3 40.4 35.5 87.9 DB-4 42.7 33.3 78.0

Example 3

Hexadecene isomerization evaluation was carried out with catalysts A-E, DB-1 to DB-4 respectively.

In a fixed-bed reactor, 2.0 g of catalyst is installed, the carrier gas is hydrogen, the flow rate of hydrogen is 50 mL/min, the weight hourly space velocity of hexadecene feed is 1 h ^-1 , the reaction temperature is 250 °C, the reaction pressure is 0.2 MPa, and hydrogen The weight ratio to hexadecene was 0.01. The continuous reaction was carried out for about 100 h, and the analysis results of the isomeric products are shown in Table 4.

Table 4

catalyst Conversion rate,% Isodecene yield, % Isomer selectivity, % A 51.3 49.2 95.9 B 52.3 49.8 95.2 C 52.8 50.3 95.3 D. 47.6 45.0 94.5 E. 48.0 45.2 94.2 DB-1 34.4 29.7 86.3 DB-2 36.7 30.5 83.1 DB-3 36.9 31.4 85.1 DB-4 35.1 28.1 80.1

In the table 2-4 of embodiment 1-3, conversion rate, isomer selectivity, isomer yield are calculated by following formula:

Conversion %=[(the amount of normal olefins in raw materials-the amount of normal olefins in isomerized products)/the amount of normal olefins in raw materials]×100%;

Isomerization selectivity%=[isomerized product isomeric olefin amount/(raw material normal olefin amount-isomerized product normal olefin amount)]×100%;

Isomer yield % = (isomerized product isomeric olefins/raw material normal olefins) x 100%.

Example 4

Catalysts A-E, DB-1 to DB-4 were used to evaluate Fischer-Tropsch light oil isomerization.

The composition of Fischer-Tropsch light oil is shown in Table 5.

In the fixed bed reactor, 2.0g of catalyst is installed, the carrier gas is hydrogen, the flow rate of hydrogen is 50mL/min, the weight hourly space velocity of Fischer-Tropsch light oil feed is 2h ^-1 , the reaction temperature is 200°C, and the reaction pressure is 0.15MPa. The weight ratio of hydrogen to Fischer-Tropsch light oil (in terms of total olefin content therein, see Table 5) is 0.03. The continuous reaction was carried out for about 100 h, and the analysis results of the isomeric products are shown in Table 6.

table 5

Table 6

catalyst Conversion rate,% Isoolefin yield, % Isomer selectivity, % A 61.2 57.9 94.6 B 63.3 60.9 96.2 C 59.0 55.7 94.5 D. 56.5 53.2 94.1 E. 55.6 52.7 94.8 DB-1 38.5 29.5 76.7 DB-2 35.4 27.1 76.5 DB-3 37.7 27.2 72.1 DB-4 32.9 25.4 77.2

Example 5

Catalysts A-E, DB-1 to DB-4 were used to evaluate Fischer-Tropsch light oil isomerization.

The composition of Fischer-Tropsch light oil is shown in Table 5.

In the fixed bed reactor, 2.0g of catalyst is installed, the carrier gas is nitrogen, the nitrogen flow rate is 50mL/min, the weight hourly space velocity of Fischer-Tropsch light oil feed is 2h ^-1 , the reaction temperature is 200°C, and the reaction pressure is 0.15MPa , the weight ratio of hydrogen to total olefins in Fischer-Tropsch light oil is 0.03. The continuous reaction was carried out for about 100 h, and the analysis results of the isomeric products are shown in Table 7.

Table 7

catalyst Conversion rate,% Isoolefin yield, % Isomer selectivity, % A 59.7 55.6 93.2 B 60.4 55.9 92.5 C 57.7 54.0 93.6 D. 55.6 51.4 92.4 E. 53.9 49.2 91.3 DB-1 37.3 27.2 72.9 DB-2 35.4 25.9 73.1 DB-3 36.2 26.2 72.4 DB-4 33.2 24.6 74.2

In the table 6 and 7 of embodiment 4 and 5, conversion rate, isomer selectivity, isomer yield are calculated by following formula:

Conversion %=[(the amount of terminal olefins in Fischer-Tropsch light oil-the amount of terminal olefins in isomerized products)/the amount of normal olefins in Fischer-Tropsch light oil]×100%;

Isomerization selectivity%=[isomerized product isomeric olefin amount/(Normal olefin amount in Fischer-Tropsch light oil-isomerized product normal olefin amount)]×100%;

Isomer yield % = (isomerized product isomeric olefins/Normal olefins in Fischer-Tropsch light oil) × 100%.

It can be seen from the results of Examples, Comparative Examples and Tables 1-7 that the catalyst AE prepared by the present invention is used to realize the isomerization of C ₄ -C ₂₀ linear olefins, and the reaction activity and isomerization selectivity are better than those of the comparison Catalysts DB-1 to DB-4 have significantly better isomerization effects on high-carbon straight-chain terminal olefins.

The preferred embodiments of the present invention have been described in detail above, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims (45)

1. A process for isomerizing linear olefins comprising:

c in the presence of hydrogen and/or inert gas ₄ -C ₂₀ Linear olefins or C-containing ₄ -C ₂₀ The Fischer-Tropsch light oil of the linear olefin is contacted with a catalyst containing ZSM-48 molecular sieve to carry out isomerization reaction, thus obtaining the catalyst containing C ₄ -C ₂₀ An isoolefin product;

wherein, C in the Fischer-Tropsch light oil ₈ The content of the above linear olefins is 60 to 80 wt%;

the catalyst containing ZSM-48 molecular sieve is prepared by the following method:

(1) Mixing ZSM-48 molecular sieve with alkali liquor, adding water for pulping to prepare mixed slurry, and filtering, washing and drying to obtain modified ZSM-48 molecular sieve;

(2) Mixing the modified ZSM-48 molecular sieve, an aluminum binder and water, adding acid liquor for kneading, and then performing extrusion molding to obtain a catalyst precursor;

(3) And sequentially carrying out hydrothermal treatment, washing with a mixed solution containing ammonium salt and acid and washing with water on the catalyst precursor, and drying to obtain the catalyst.

2. The isomerization process of claim 1 wherein the isomerization reaction conditions include: the temperature is 100-400 ℃; the pressure is 0-3MPa; hydrogen and/or inert gas with C ₄ -C ₂₀ The weight ratio of the linear olefin is not more than 0.2; c (C) ₄ -C ₂₀ Weight hourly space velocity of linear olefins from 0.5 to 5h ^-1 。

3. The isomerization process of claim 2 wherein the isomerization reaction conditions include: the temperature is 200-300 ℃; the pressure is 0-0.5MPa; hydrogen and/or inert gas with C ₄ -C ₂₀ The weight ratio of the linear olefin is 0.01-0.05; c (C) ₄ -C ₂₀ Weight hourly space velocity of linear olefins1-2h ^-1 。

4. The isomerization process of claim 1 wherein in step (1) the ZSM-48 molecular sieve is SiO ₂ /Al ₂ O ₃ The molar ratio of (2) is 50-200;

and/or the alkali liquor is ammonia, na ₂ CO ₃ Or NaOH solution;

and/or the concentration of the alkali liquor is 0.01-0.2M;

and/or, water: ZSM-48 molecular sieve (1-20): 1, a step of;

and/or, pulping at 25-80deg.C; the pulping time is 0.5-24h.

5. The isomerization process of claim 4 wherein in step (1) the ZSM-48 molecular sieve is SiO ₂ /Al ₂ O ₃ The molar ratio of (2) is 60-150;

and/or the concentration of the alkali liquor is 0.05-0.1M;

and/or, water: the mass ratio of the ZSM-48 molecular sieve is (2-5): 1, a step of;

and/or, pulping at 40-60deg.C; the pulping time is 1-3h.

6. The isomerization process of any one of claims 1-5 wherein in step (2) the aluminum binder is selected from at least one of pseudo-boehmite, an aluminum sol, an aluminum hydroxide gel, and boehmite;

and/or the aluminum binder is as Al ₂ O ₃ The weight ratio of the modified ZSM-48 molecular sieve to the aluminum binder is 0.1-4 based on dry basis: 1, a step of;

and/or the acid liquor is a nitric acid solution and/or a phosphoric acid solution.

7. The isomerization process according to claim 6, wherein in step (2), the aluminum binder is as Al ₂ O ₃ The weight ratio of the modified ZSM-48 molecular sieve to the aluminum binder is 1-3:1 on a dry basis.

8. The isomerization process of any one of claims 1-5, 7 wherein in step (3), the hydrothermal treatment comprises: continuously introducing water into the catalyst precursor to treat by taking nitrogen as carrier gas, wherein the hydrothermal treatment temperature is 200-500 ℃; the hydrothermal treatment time is 0.5-6h.

9. The isomerization process of claim 8 wherein the hydrothermal treatment temperature is 300-400 ℃.

10. The isomerization process of claim 8 wherein the water throughput is 10-50mL/h relative to 100g of the catalyst precursor.

11. The isomerization process of claim 9 wherein the water throughput is 10-50mL/h relative to 100g of the catalyst precursor.

12. The isomerization process of claim 6 wherein in step (3) the hydrothermal treatment comprises: continuously introducing water into the catalyst precursor to treat by taking nitrogen as carrier gas, wherein the hydrothermal treatment temperature is 200-500 ℃; the hydrothermal treatment time is 0.5-6h.

13. The isomerization process of claim 12 wherein the hydrothermal treatment temperature is 300-400 ℃.

14. The isomerization process of claim 12 or 13 wherein the water throughput is 10-50mL/h relative to 100g of the catalyst precursor.

15. The isomerization process of any one of claims 1 to 5, 7, 9 to 13 wherein in step (3), the concentration of the ammonium salt in the mixed solution is 0.05 to 0.5M and the concentration of the acid is 0.05 to 0.5M;

and/or the washing temperature of the mixed solution is 40-90 ℃; the washing time of the mixed solution is 0.1-5h.

16. The isomerization process of claim 15 wherein in step (3) the concentration of the ammonium salt in the mixed solution is 0.1-0.2M and the concentration of the acid is 0.1-0.2M;

and/or the washing temperature of the mixed solution is 60-80 ℃; the washing time of the mixed solution is 0.5-1h.

17. The isomerization process according to claim 6, wherein in step (3), the concentration of the ammonium salt in the mixed solution is 0.05 to 0.5M and the concentration of the acid is 0.05 to 0.5M;

and/or the washing temperature of the mixed solution is 40-90 ℃; the washing time of the mixed solution is 0.1-5h.

18. The isomerization process of claim 17 wherein in step (3) the concentration of the ammonium salt in the mixed solution is 0.1-0.2M and the concentration of the acid is 0.1-0.2M;

and/or the washing temperature of the mixed solution is 60-80 ℃; the washing time of the mixed solution is 0.5-1h.

19. The isomerization process according to claim 8, wherein in step (3), the concentration of the ammonium salt in the mixed solution is 0.05 to 0.5M and the concentration of the acid is 0.05 to 0.5M;

and/or the washing temperature of the mixed solution is 40-90 ℃; the washing time of the mixed solution is 0.1-5h.

20. The isomerization process of claim 19 wherein in step (3) the concentration of the ammonium salt in the mixed solution is 0.1-0.2M and the concentration of the acid is 0.1-0.2M;

and/or the washing temperature of the mixed solution is 60-80 ℃; the washing time of the mixed solution is 0.5-1h.

21. The isomerization process according to claim 14 wherein in step (3), the concentration of the ammonium salt in the mixed solution is 0.05-0.5M and the concentration of the acid is 0.05-0.5M;

and/or the washing temperature of the mixed solution is 40-90 ℃; the washing time of the mixed solution is 0.1-5h.

22. The isomerization process of claim 21 wherein in step (3) the concentration of the ammonium salt in the mixed solution is 0.1-0.2M and the concentration of the acid is 0.1-0.2M;

and/or the washing temperature of the mixed solution is 60-80 ℃; the washing time of the mixed solution is 0.5-1h.

23. The isomerization process of any one of claims 1-5, 7, 9-13, 16-22 wherein the ammonium salt is at least one of ammonium sulfate, ammonium chloride, ammonium nitrate; the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid.

24. The isomerization process of claim 23 wherein the ammonium salt is ammonium sulfate; the acid is sulfuric acid.

25. The isomerization process according to claim 6, wherein the ammonium salt is at least one of ammonium sulfate, ammonium chloride, ammonium nitrate; the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid.

26. The isomerization process of claim 25 wherein the ammonium salt is ammonium sulfate; the acid is sulfuric acid.

27. The isomerization process of claim 8 wherein the ammonium salt is at least one of ammonium sulfate, ammonium chloride, ammonium nitrate; the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid.

28. The isomerization process of claim 27 wherein the ammonium salt is ammonium sulfate; the acid is sulfuric acid.

29. The isomerization process of claim 14 wherein the ammonium salt is at least one of ammonium sulfate, ammonium chloride, ammonium nitrate; the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid.

30. The isomerization process of claim 29 wherein the ammonium salt is ammonium sulfate; the acid is sulfuric acid.

31. The isomerization process of claim 15 wherein the ammonium salt is at least one of ammonium sulfate, ammonium chloride, ammonium nitrate; the acid is at least one of sulfuric acid, hydrochloric acid and nitric acid.

32. The isomerization process of claim 31 wherein the ammonium salt is ammonium sulfate; the acid is sulfuric acid.

33. The isomerization process of any one of claims 1-5, 7, 9-13, 16-22, 24-32 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

34. The isomerization process of claim 6 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

35. The isomerization process of claim 8 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

36. The isomerization process of claim 14 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

37. The isomerization process of claim 15 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

38. The isomerization process of claim 23 wherein the water wash comprises: washing with deionized water, and filtering until the pH value of the obtained filtrate is 7-8;

and/or the temperature of the drying is 100-120 ℃ and the time is 12-24h.

39. The isomerization process of any one of claims 1-5, 7, 9-13, 16-22, 24-32, 34-38 wherein the catalyst has a specific surface area of 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.

40. The isomerization process according to claim 6, wherein the specific surface area of the catalyst is 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.

41. The isomerization process according to claim 8, wherein the specific surface area of the catalyst is 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is notLess than 65 mu mol/g, and the content of the strong acid is more than 60%.

42. The isomerization process of claim 14 wherein the catalyst has a specific surface area of 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.

43. The isomerization process of claim 15 wherein the catalyst has a specific surface area of 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.

44. The isomerization process of claim 23 wherein the catalyst has a specific surface area of 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.

45. The isomerization process of claim 33 wherein the catalyst has a specific surface area of 200-300m ² Per gram, pore volume of 0.4-0.8cm ³ /g; the total pyridine infrared acid amount of the catalyst is not less than 65 mu mol/g, and the strong acid amount is more than 60%.