A process for the preparation of linear alkylbenzenes by alkylation

Abstract

An alkylation reaction method for preparing linear alkylbenzene, characterized in that, under alkylation reaction conditions, a substantially linear olefin is contacted with an aromatic hydrocarbon in the presence of a solid acid catalyst, the solid acid catalyst comprising a molecular sieve and a heat-resistant inorganic oxide, the molecular sieve having a mesopore volume accounting for 15-35% of the total pore volume, a total acid amount higher than 2500 μmol / g, and a ratio of B value to T value being 1.5-6, wherein the B value represents the mass fraction of Al2O3 on the surface of the molecular sieve, and the T value represents the mass fraction of Al2O3 in the bulk phase of the molecular sieve.

Description

Technical Field

[0001] The present invention relates to an alkylation reaction method, and more particularly to an alkylation reaction method for preparing linear alkylbenzene from linear olefins. Background Art

[0002] Long-chain alkylbenzenes are an important raw material for the production of sodium alkylbenzene sulfonate, a synthetic detergent. Long-chain alkylbenzenes are primarily produced by the alkylation of long-chain olefins with benzene. Currently, commercial catalysts for this reaction are primarily HF or AlCl₃. However, these two catalytic systems pose significant safety and environmental risks and are being phased out as safety and environmental standards continue to rise. The development of a new, corrosion-free, and pollution-free solid acid alkylation method as an alternative technology is an inevitable trend in long-chain alkylbenzene production technology.

[0003] Currently, the industrial solid acid process uses the fluorine-containing SiO2-Al2O3 solid acid catalyst (ZL93104573.8) jointly developed by UOP of the United States and Petresa of Spain. Since the catalyst itself contains fluorine, it is corrosive to equipment and still has certain safety and environmental risks.

[0004] Zeolite molecular sieve catalyst systems have received extensive research both domestically and internationally. Because long-chain alkylbenzene molecules are relatively large, they are unable to access pores with ten-membered rings or fewer. Only molecular sieves such as MOR, Y, and Beta, which have pores with twelve or more rings, exhibit good catalytic performance in the alkylation of benzene with long-chain olefins (Catal Surv Asia (2014) 18:1-12; Catal Today (2017) 298:109-116). The primary challenge in the synthesis of long-chain alkylbenzenes using molecular sieves is their short service life and low linearity. Y molecular sieve is widely used in the petrochemical industry and is the most widely used molecular sieve in petrochemical applications. Its acid distribution and diffusion properties are key factors affecting the alkylation life and product linearity of linear long-chain olefins.

[0005] CN107867699A discloses a Y zeolite containing regular ultra-large micropores. By subjecting the selected Y zeolite to template and acid-base treatment, a Y zeolite with regular ultra-large micropores of 1 to 2 nm is constructed. Due to the abundant acid centers and suitable reaction channels provided by the regular ultra-large micropores, higher conversion rate and selectivity are achieved.

[0006] CN110562995A discloses a method for synthesizing nano Y zeolite and its application in the synthesis of linear alkylbenzenes. Due to the catalyst crystals, the diffusion resistance is small, and the activity and stability of the alkylation of long-chain olefins are improved. Summary of the Invention

[0007] After extensive research, the inventors discovered that when molecular sieve acid is distributed on the surface and the pore distribution is optimal, it significantly impacts the activity and selectivity of a process for preparing linear alkylbenzenes. Therefore, the present invention provides an alkylation process for preparing linear alkylbenzenes with excellent alkylation activity and linearity.

[0008] To achieve the object of the present invention, the present invention provides an alkylation reaction method for preparing linear alkylbenzene, characterized in that, under alkylation reaction conditions, a substantially linear olefin and an aromatic hydrocarbon are contacted in the presence of a solid acid catalyst, wherein the solid acid catalyst comprises a molecular sieve and a heat-resistant inorganic oxide, and the molecular sieve has a mesopore volume accounting for 15% to 35% of the total pore volume, an acid content greater than 2500 μmol / g, and a ratio of B value to T value of 1.5 to 6, wherein the B value represents the Al2O3 mass fraction on the molecular sieve surface, and the T value represents the Al2O3 mass fraction in the molecular sieve bulk.

[0009] The alkylation of primarily linear olefins with aromatic hydrocarbons presents significant challenges to the activity and selectivity of the reaction due to the long length of the olefins, the activation of the linear olefins, and skeletal isomerization. The reaction method provided by the present invention utilizes a molecular sieve catalyst with a suitable acid and pore distribution as the active component, thereby improving the accessibility of the acid sites of the linear olefins and alkylbenzene products. A high acid content ensures high alkylation activity, while a suitable pore distribution facilitates the alkylation reaction and suppresses side reactions such as skeletal isomerization. Consequently, the reaction method of the present invention significantly improves both monoalkylbenzene selectivity and linearity. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a trend diagram of the monoalkylbenzene selectivity and alkylbenzene linearity of the alkylation reaction process of dodecene with benzene. DETAILED DESCRIPTION

[0011] The present invention provides an alkylation reaction method for preparing linear alkylbenzene, characterized in that, under alkylation reaction conditions, substantially linear olefins and aromatic hydrocarbons are contacted in the presence of a solid acid catalyst, wherein the solid acid catalyst comprises a molecular sieve and a heat-resistant inorganic oxide, and the molecular sieve has a mesopore volume accounting for 15% to 35% of the total pore volume, an acid content higher than 2500 μmol / g, and a ratio of B value to T value of 1.5 to 6, wherein the B value represents the Al2O3 mass fraction on the molecular sieve surface, and the T value represents the Al2O3 mass fraction in the molecular sieve bulk.

[0012] In the reaction method of the present invention, the substantially linear olefin is a linear olefin having double bonds at terminal and internal positions, or a mixture of linear alpha olefins having double bonds at terminal positions. Preferably, the substantially linear olefin has 8 to 28 carbon atoms; more preferably, the substantially linear olefin has 8 to 15 carbon atoms; and even more preferably, the linear olefin has 10 to 14 carbon atoms. The substantially linear olefin can be prepared by various known methods, such as paraffin dehydrogenation, cracking, and small olefin oligomerization. For ease of description, the aromatic hydrocarbon is described herein as benzene.

[0013] In the reaction method of the present invention, substantially linear olefins and benzene are reacted under reaction conditions and in the presence of a catalyst. Suitable alkylation reaction conditions are selected to minimize the isomerization of the alkyl group and minimize the polyalkylation of benzene (or the aromatic structure of other aromatic compounds), while simultaneously maximizing the consumption of olefins to maximize the product. Temperature, pressure, benzene-olefin molar ratio, and feed olefin space velocity all affect the reaction. The higher the temperature, the higher the olefin conversion rate, but thermodynamically it is not conducive to the selectivity of linear alkylbenzenes. Therefore, the temperature should be suitable, and the suitable temperature range of molecular sieves with different acid strengths is not very consistent. The choice of pressure is to ensure that benzene and olefins are in the liquid phase at the corresponding temperature, that is, to be higher than the saturated vapor pressure at the corresponding temperature. The higher the benzene-olefin molar ratio, the more favorable the olefin conversion and product selectivity, but it also increases energy consumption, so there is also an appropriate range and it cannot be infinitely high. The greater the feed olefin space velocity, the more favorable the selectivity, but the catalyst has limited conversion capacity. If the space velocity is too high, the conversion is incomplete and the olefins will penetrate. Therefore, taking all factors into consideration, the alkylation reaction conditions are preferably a temperature of 50-250°C, a pressure of 0.1-7 MPa, a benzene-olefin molar ratio of 3:1-80:1, and a feed olefin space velocity of 0.1-5 h -1 More preferably, the alkylation reaction conditions are a temperature of 70 to 200°C, a pressure of 2 to 4 MPa, a benzene-olefin molar ratio of 4:1 to 60:1, and a feed olefin space velocity of 0.3 to 2 h -1 Under the alkylation reaction conditions, the contact is carried out in the liquid phase, that is, the reaction pressure is ensured to be higher than the saturated vapor pressure of the olefin and benzene at the corresponding reaction temperature, so that the benzene and olefin reaction materials are both in the liquid phase for the contact reaction.

[0014] The reaction method of the present invention is carried out in the presence of a solid acid catalyst, which comprises a molecular sieve and a heat-resistant inorganic oxide.

[0015] The molecular sieve has the characteristic of being aluminum-rich on the surface, and the ratio of its B value to T value is 1.5 to 6. Preferably, the ratio of B value to T value is 2 to 4, wherein the B value represents the Al2O3 mass fraction on the molecular sieve surface, and the T value represents the Al2O3 mass fraction in the molecular sieve bulk.

[0016] The molecular sieve is preferably a silica-alumina molecular sieve, more preferably a molecular sieve selected from Y, MCM-22, beta or MOR, and most preferably a Y molecular sieve.

[0017] The molecular sieve, the acid content of medium-strong acid accounts for preferably not less than 40% of the total acid content, more preferably 40-60%. The acid content is determined by NH3-TPD, wherein the desorption amount at 250-450°C is defined as the medium-strong acid content, and the total desorption amount is defined as the total acid content.

[0018] According to the definition of the International Union of Pure and Applied Chemistry (IUPAC), pores with a pore size of 2-50 nm are called mesopores (or mesopores). The molecular sieve has a mesopore volume that accounts for 15% to 35% of the total pore volume, preferably 17% to 25%. The ratio of the mesopore volume to the total pore volume is determined by BET.

[0019] In the reaction method of the present invention, the molecular sieve used is prepared by a method comprising the following steps: calcining a sodium-type molecular sieve under a slightly positive pressure in an alkaline atmosphere; performing a first ammonium exchange on the calcined molecular sieve; performing cation adsorption on the molecular sieve after the first ammonium exchange; performing an acid treatment on the molecular sieve after the cation adsorption; and performing a second ammonium exchange on the molecular sieve after the acid treatment and recovering the product.

[0020] The sodium molecular sieve is preferably a NaY molecular sieve, having a silicon-aluminum molecular ratio of 4 to 8, a relative crystallinity greater than 95%, and a sodium oxide mass fraction of 2 to 5%. The alkaline atmosphere is preferably an ammonia atmosphere with a concentration of 0.05 to 0.5 M. The calcination under slightly positive pressure is preferably carried out at a gauge pressure of 0.01 to 0.1 MPa and a temperature of 400 to 600°C.

[0021] The first ammonium exchange is performed using an ammonium salt solution, wherein the ammonium salt is selected from one or more of ammonium nitrate, ammonium chloride or ammonium sulfate, the concentration of the ammonium salt solution is 50-200 g / L, the ammonium exchange temperature is 50-90° C., and the ammonium exchange time is 0.5-2 h.

[0022] In the cation adsorption, the cation is selected from For example, the cation is selected from NH4 + 、Ag + , K + 、Cs + The compound used for cation adsorption can be selected from, but not limited to, one or more of ammonium nitrate, silver nitrate, potassium nitrate, or cesium chloride. The cation concentration is 1 to 5 mmol / g molecular sieve, the mass ratio of the cation solution volume to the molecular sieve is 2 to 10 ml / g, and the adsorption temperature is 50 to 80°C.

[0023] The acid treatment is performed with one or more of hydrochloric acid, nitric acid, fluorosilicic acid, ammonium fluoride, ammonium hexafluorosilicate, and ammonium bifluoride, preferably one or more of fluorosilicic acid, ammonium fluoride, ammonium hexafluorosilicate, and ammonium bifluoride. The acid concentration is 1 to 50 g / L, the mass ratio of the acid solution to the molecular sieve is 1 to 10:1, and the acid treatment temperature is 40 to 80°C.

[0024] The second ammonium exchange is carried out using an ammonium salt solution, the ammonium salt is selected from one or more of ammonium nitrate, ammonium chloride or ammonium sulfate, the concentration of the ammonium salt solution is 50-200 g / L, the ammonium exchange temperature is 50-90° C., and the ammonium exchange time is 0.5-2 h.

[0025] In the solid acid catalyst used in the reaction method of the present invention, the molecular sieve and the heat-resistant inorganic oxide have a weight ratio of 99:1-20:80, preferably 95:5-25:75, and more preferably 90:10-50:50 on a dry basis. The heat-resistant inorganic oxide is selected from at least one of alumina, zirconia, silica and titanium dioxide. The solid acid catalyst is formed by mixing the molecular sieve with the heat-resistant inorganic oxide or its precursor, acid solution, auxiliary agent and water, and then drying and calcining. The forming, drying and calcining are all conventional operations in the art and are well known to those skilled in the art. For example, the calcining conditions include: a calcination temperature of 350-650°C and a calcination time of 0.5-8h, which will not be described in detail here.

[0026] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used can be obtained from commercial channels.

[0027] In the embodiments, the mass fraction of Al2O3 in the bulk phase of the molecular sieve is determined by XRF, the mass fraction of Al2O3 on the surface of the molecular sieve is determined by XPS, the ratio of the mesopore volume to the total pore volume is determined by BET, and the acid amount is determined by NH3-TPD, wherein the desorption amount at 250°C to 450°C is defined as the medium-strong acid amount, the total desorption amount is defined as the total acid amount, and the proportion of the medium-strong acid amount is the percentage of the medium-strong acid amount to the total acid amount.

[0028] Examples 1-8 illustrate the preparation of the solid acid catalyst in the method of the present invention.

[0029] Example 1

[0030] Preparation of Y molecular sieve:

[0031] (1) Calcination: NaY molecular sieve (n(SiO2) / n(Al2O3)=5, relative crystallinity 96%, w(Na2O)=4%) was calcined at 550°C for 1 h under a pressure of 0.02 MPa while introducing 1 M ammonia solution at 0.1 ml / min during the calcination process;

[0032] (2) First ammonium exchange: the calcined molecular sieve was subjected to ammonium exchange using ammonium chloride solution at a concentration of 150 g / L, an exchange temperature of 80°C, an exchange time of 1 h, a solution to molecular sieve mass ratio of 4, and three exchanges using the same method, with w(Na2O) = 0.2%;

[0033] (3) Cation adsorption, the cation is NH4NO3, the ratio of ammonium nitrate solution to catalyst is 5 ml / g, and the cation concentration is 3 mmol / g;

[0034] (4) Acid treatment: (NH4)2SiF6 was used to treat the cationic adsorption molecular sieve with acid, the acid concentration was 10 g / L, the mass ratio of the acid solution to the catalyst was 5, and the acid treatment temperature was 60°C;

[0035] (5) Second ammonium exchange: ammonium exchange is performed on the acid-treated molecular sieve. Use ammonium chloride solution with a concentration of 150 g / L, an exchange temperature of 80°C, an exchange time of 1 h, a solution to molecular sieve mass ratio of 4, and exchange once using the same method, with w(Na2O) = 0.05%;

[0036] (6) The slurry is filtered, washed and dried to obtain the finished molecular sieve.

[0037] The molecular sieve Y1 was subjected to XRF, XPS, BET and NH3-TPD analysis, and the results of bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume ratio and acid content were shown in Table 1.

[0038] In Table 1, the bulk Al2O3 mass fraction is represented by T value, the surface Al2O3 mass fraction is represented by B value, and the mesopore volume is represented by V value. 介 The ratio of mesopore volume to total pore volume is expressed as V 介 / V 总 express.

[0039] Preparation of solid acid catalyst:

[0040] Take the molecular sieve sample Y1 and pseudo-boehmite (average particle size of 100 μm, Sinopec Catalyst Co., Ltd.) and mix them in a dry weight percentage of 80:20, add 3wt% of sesbania powder and 3wt% of nitric acid respectively (based on the total dry weight of the molecular sieve and pseudo-boehmite), add 1 times the weight of deionized water based on the dry basis of the molecular sieve and pseudo-boehmite, mix well and then extrude into shape, dry at 110°C so that the dry basis weight of the mixed molded product after drying is 65wt%, and then air-roast at 550°C for 4h to obtain a solid acid catalyst.

[0041] Comparative Example 1

[0042] The XRF, XPS, BET and NH3-TPD analysis results of commercially purchased USY molecular sieve are shown in Table 1.

[0043] The preparation of the solid acid catalyst is the same as in Example 1.

[0044] Comparative Example 2

[0045] The same as Example 1, except that (3), (4), and (5) are omitted, i.e., there is no cation adsorption, acid treatment, and second ammonium exchange step. The resulting comparative molecular sieve is numbered DY1-1. Molecular sieve DY1-1 was subjected to XRF, XPS, BET, and NH3-TPD analysis, and the results of the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content are shown in Table 1.

[0046] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0047] Comparative Example 3

[0048] The same as Example 1, except that step (3) is omitted, i.e., the cation adsorption step is omitted. The comparative molecular sieve obtained is numbered DY1-2. Molecular sieve DY1-2 was subjected to XRF, XPS, BET, and NH3-TPD analysis, and the results of bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content are shown in Table 1.

[0049] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0050] Comparative Example 4

[0051] The same as Example 1, except that step (4), i.e., the acid treatment step, is omitted. The resulting comparative molecular sieve is numbered DY1-3. Molecular sieve DY1-3 was subjected to XRF, XPS, BET, and NH3-TPD analysis, and the results of bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content are shown in Table 1.

[0052] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0053] Comparative Example 5

[0054] The same as Example 1, except that Cu(NO₃)₂ was used as the cation in the cation adsorption step in step (3). The resulting comparative molecular sieve was designated DY1-4. XRF, XPS, BET, and NH₃-TPD analyses of molecular sieve DY1-4 revealed the bulk Al₂O₃ mass fraction, surface Al₂O₃ mass fraction, mesopore volume fraction, and acid content, as shown in Table 1.

[0055] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0056] Example 2

[0057] Same as Example 1, except that the cation in (3) cation adsorption is Cs + (CsCl), numbered Y2. XRF, XPS, BET, and NH3-TPD analysis revealed the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content, as shown in Table 1.

[0058] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0059] Example 3

[0060] Same as Example 1, except that the cation in (3) cation adsorption is Ag + The (AgNO3) is numbered as Y3. XRF, XPS, BET and NH3-TPD analysis showed the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction and acid content as shown in Table 1.

[0061] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0062] Example 4

[0063] Same as Example 1, except that the cation in (3) cation adsorption is K + (KNO3), numbered Y4. XRF, XPS, BET, and NH3-TPD analyses yielded the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content, as shown in Table 1.

[0064] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0065] Example 5

[0066] Same as Example 1, except that the acid used in (4) the acid treatment was HNO3. Sample number Y5. XRF, XPS, BET, and NH3-TPD analyses yielded the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume fraction, and acid content, as shown in Table 1.

[0067] The preparation of the solid acid catalyst comparison sample is the same as in Example 1.

[0068] Example 6

[0069] Preparation of MCM-22 molecular sieve:

[0070] (1) Calcination: MCM-22 molecular sieve (n(SiO2) / n(Al2O3)=3.2, relative crystallinity 91%, w(Na2O)=2%) was calcined at 400°C under a pressure of 0.01 MPa for 1 h, while 0.05 M ammonia solution was introduced at 0.1 ml / min during the calcination process;

[0071] (2) First ammonium exchange: the calcined molecular sieve was subjected to ammonium exchange using ammonium chloride solution at a concentration of 50 g / L, an exchange temperature of 50°C, an exchange time of 0.5 h, a solution to molecular sieve mass ratio of 4, and three exchanges using the same method, with w(Na2O) = 0.5%;

[0072] (3) Cation adsorption, the cation is AgNO3, the ratio of cationic silver nitrate solution to catalyst is 2 ml / g, and the cation concentration is 5 mmol / g;

[0073] (4) Acid treatment: the cationic adsorption molecular sieve is treated with fluorosilicic acid, the acid concentration is 1 g / L, the mass ratio of the acid solution to the catalyst is 10, and the acid treatment temperature is 40°C;

[0074] (5) Second ammonium exchange: the acid-treated molecular sieve is subjected to ammonium exchange. An ammonium chloride solution with a concentration of 50 g / L, an exchange temperature of 50°C, an exchange time of 0.5 h, a solution to molecular sieve mass ratio of 4, and one exchange using the same method, with w(Na2O) = 0.08%;

[0075] (6) The slurry is filtered, washed and dried to obtain the finished molecular sieve.

[0076] The molecular sieve MCM-22 was subjected to XRF, XPS, BET and NH3-TPD analysis, and the results of bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume ratio and acid content were shown in Table 1.

[0077] The preparation of the solid acid catalyst comparison sample was the same as in Example 1, except that the molecular sieve MCM-22 prepared in this example was used instead of Y1.

[0078] Example 7

[0079] Preparation of β molecular sieve:

[0080] (1) Calcination: β molecular sieve (n(SiO2) / n(Al2O3)=15, relative crystallinity 88%, w(Na2O)=5%), calcined at 600°C under a pressure of 0.1 MPa for 1 h, while simultaneously introducing 0.5 M ammonia solution at 0.1 ml / min during the calcination process;

[0081] (2) first ammonium exchange, the ammonium exchange of the calcined molecular sieve is carried out by using an ammonium chloride solution with a concentration of 200 g / L, an exchange temperature of 90°C, an exchange time of 2 h, and a solution to molecular sieve mass ratio of 4, and the same method is used for exchange for 3 times, w(Na2O) = 0.3%;

[0082] (3) cation adsorption, the cation is KNO3, the cation potassium nitrate solution to catalyst ratio is 10 ml / g, and the cation concentration is 1 mmol / g;

[0083] (4) acid treatment, the acid treatment of the cation adsorbed molecular sieve is carried out by using ammonium fluoride, the acid concentration is 50 g / L, the acid solution to catalyst mass ratio is 1, and the acid treatment temperature is 40°C;

[0084] (5) second ammonium exchange, the ammonium exchange of the acid treated molecular sieve is carried out by using an ammonium chloride solution with a concentration of 200 g / L, an exchange temperature of 90°C, an exchange time of 2 h, and a solution to molecular sieve mass ratio of 4, and the same method is used for exchange for 1 time, w(Na2O) = 0.05%;

[0085] (6) after the above slurry filtration, washing and drying, the finished product molecular sieve is obtained.

[0086] The molecular sieve β is subjected to XRF, XPS, BET and NH3-TPD analysis, and the bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume ratio and acid amount results are shown in Table 1.

[0087] The preparation of the solid acid catalyst comparative sample is the same as in Example 1, except that the molecular sieve β prepared in this example is used to replace Y1.

[0088] Example 8

[0089] MOR molecular sieve is prepared:

[0090] (1) calcination, the MOR molecular sieve (n(SiO2) / n(Al2O3) = 10, relative crystallinity 100.3%, w(Na2O) = 2.1%) is calcined at 500°C for 1 h under a pressure of 0.02 MPa, and 0.1 M ammonia water is introduced at a rate of 0.1 ml / min during the calcination process;

[0091] (2) first ammonium exchange, the ammonium exchange of the calcined molecular sieve is carried out by using an ammonium chloride solution with a concentration of 100 g / L, an exchange temperature of 70°C, an exchange time of 1 h, and a solution to molecular sieve mass ratio of 4, and the same method is used for exchange for 3 times, w(Na2O) = 0.4%;

[0092] (3) cation adsorption, the cation is CsCl, the cation cesium chloride solution to catalyst ratio is 5 ml / g, and the cation concentration is 2 mmol / g;

[0093] (4) Acid treatment: the cationic adsorption molecular sieve is treated with ammonium fluoride, the acid concentration is 20 g / L, the mass ratio of the acid solution to the catalyst is 5, and the acid treatment temperature is 80°C;

[0094] (5) Second ammonium exchange: ammonium exchange is performed on the acid-treated molecular sieve. Use ammonium chloride solution with a concentration of 100 g / L, an exchange temperature of 70°C, an exchange time of 1 h, a solution to molecular sieve mass ratio of 4, and exchange once using the same method, with w(Na2O) = 0.06%;

[0095] (6) The slurry is filtered, washed and dried to obtain the finished molecular sieve.

[0096] The molecular sieve MOR was subjected to XRF, XPS, BET and NH3-TPD analysis, and the results of bulk Al2O3 mass fraction, surface Al2O3 mass fraction, mesopore volume ratio and acid content were shown in Table 1.

[0097] The preparation of the solid acid catalyst comparison sample was the same as in Example 1, except that the molecular sieve MOR prepared in this example was used instead of Y1.

[0098] Table 1

[0099]

[0100] Examples 9-20 illustrate the alkylation reaction method for preparing linear alkylbenzene provided by the present invention.

[0101] Example 9

[0102] The solid acid catalyst sample of Example 1 was used to carry out the alkylation reaction of benzene with dodecene at 120°C and 3 MPa, with a hydrocarbon feed space velocity of 0.354 h -1 , the molar ratio of feed benzene to olefin was 60. The conversion of dodecene and the selectivity of monoalkylbenzene under the reaction conditions are shown in Table 2.

[0103] The results of the stable operation evaluation are shown in the attached figure. It can be seen from the attached figure that during the 150-hour stable operation evaluation, the monoalkylbenzene selectivity was always close to 100%, and the alkylbenzene linearity was always above 91%.

[0104] Comparative Examples 6-10

[0105] The solid acid catalysts of Comparative Examples 1-5 were used to perform the alkylation reaction of benzene with dodecene at 120°C and 3 MPa, with a hydrocarbon feed space velocity of 0.354 h -1 , the molar ratio of feed benzene to olefin was 60. The conversion of dodecene and the selectivity of monoalkylbenzene under the reaction conditions are shown in Table 2.

[0106] Table 2

[0107] Example 9 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 6h Dodecene conversion rate / % 100 99.9 99.9 99.9 99.9 99.9 Monoalkylbenzene selectivity / % 99.1 93.4 92.8 98.3 91.5 90.4 2-LAB ratio / % 29.2 24.5 25.3 26.5 23.5 25.7 Linearity / % 91.2 86.5 86.1 85.8 87.2 89.1 10h Dodecene conversion rate / % 100 99.9 98.9 99.9 95.8 87.6 Monoalkylbenzene selectivity / % 99.2 89.3 85.2 92.5 82.7 81.5 2-LAB ratio / % 30.0 24.1 24.3 25.8 22.8 24.4 Linearity / % 91.2 86.5 87.2 84.3 88.2 94.3 60h Dodecene conversion rate / % 99.4 93.7 85.0 95.5 74.3 61.2 Monoalkylbenzene selectivity / % 98.8 94.3 65.2 93.5 62.5 52.4 2-LAB ratio / % 24.7 24.2 22.2 24.6 21.2 23.9 Linearity / % 91.7 89.9 95.0 87.4 96.1 98.5

[0108] As can be seen from Table 2, the activity and selectivity of the solid acid catalyst prepared by the method of Example 1 in catalyzing the alkylation of dodecene with benzene are both much higher than those of Comparative Example 1, in which the linearity of the alkylbenzene reaches more than 91%, the product has properties comparable to those of the HF method, and the initial 2-LAB ratio is nearly 30%, which is superior to the HF method.

[0109] Examples 10-13

[0110] The alkylation of benzene with dodecene was carried out using the solid acid catalyst samples of Examples 2-5 respectively under the reaction conditions of 120°C and 3 MPa, with a hydrocarbon feed space velocity of 0.354 h -1 and a benzene to olefin molar ratio of 60. The conversion and product selectivity results under these reaction conditions are shown in Table 3.

[0111] Table 3

[0112]

[0113] Examples 14-16

[0114] The alkylation of benzene with dodecene was carried out using the solid acid catalyst samples of Examples 6-8 respectively under the reaction conditions of 120°C and 3 MPa, with a hydrocarbon feed space velocity of 0.354 h -1 and a benzene to olefin molar ratio of 60. The conversion and product selectivity results under these reaction conditions are shown in Table 4.

[0115] Table 4

[0116]

[0117] Example 17

[0118] The same as Example 9, except that the reaction conditions were changed to a temperature of 90°C, a pressure of 2 MPa, an olefin feed space velocity of 0.7 h -1 , and a benzene to olefin ratio of 10. The conversion and product selectivity results under these reaction conditions are shown in Table 5.

[0119] Example 18

[0120] The same as Example 9, except that the reaction conditions were changed to a temperature of 150°C, a pressure of 4 MPa, an olefin feed space velocity of 2 h -1 , and a benzene to olefin ratio of 30. The conversion and product selectivity results under these reaction conditions are shown in Table 5.

[0121] Example 19

[0122] Same as Example 9, except that the reaction conditions were changed to temperature 240°C, pressure 0.2 MPa, and olefin feed space velocity 5 h -1 The benzene-olefin ratio was 80:1. The conversion and product selectivity under these reaction conditions are shown in Table 5.

[0123] Example 20

[0124] Same as Example 9, except that the reaction conditions were changed to temperature 50°C, pressure 6 MPa, and olefin feed space velocity 0.2 h -1 The conversion rate and product selectivity under the reaction conditions are shown in Table 5.

[0125] Table 5

[0126]

Claims

1. An alkylation reaction method for preparing linear alkylbenzene, characterized in that: Under alkylation reaction conditions, a substantially linear olefin and an aromatic hydrocarbon are contacted in the presence of a solid acid catalyst, wherein the substantially linear olefin has 8 to 28 carbon atoms and is a linear olefin having double bonds at terminal and internal positions or a mixture of linear alpha olefins having double bonds at terminal positions; the solid acid catalyst is a molecular sieve and a heat-resistant inorganic oxide, wherein the molecular sieve is selected from Y and MCM-22; The molecular sieve has a mesopore volume of 15% to 35% of the total pore volume, a total acid content of greater than 2500 μmol / g, and a medium-strong acid content of not less than 40% of the total acid content, wherein the acid content is determined by NH3-TPD, wherein the desorption amount at 250 to 450°C is defined as the medium-strong acid content, and the ratio of the B value to the T value is 2 to 4, wherein the B value represents the Al2O3 mass fraction on the molecular sieve surface, and the T value represents the Al2O3 mass fraction in the molecular sieve bulk phase; The molecular sieve is prepared by a method comprising the following steps: calcining a sodium molecular sieve under a slightly positive pressure in an alkaline atmosphere; performing a first ammonium exchange on the calcined molecular sieve; performing cation adsorption on the molecular sieve after the first ammonium exchange; performing an acid treatment on the molecular sieve after the cation adsorption; performing a second ammonium exchange on the molecular sieve after the acid treatment and recovering the product, wherein the alkaline atmosphere is an ammonia atmosphere with a concentration of 0.05 to 0.5 M; the calcination under the slightly positive pressure is performed at a gauge pressure of 0.01 to 0.1 MPa and a temperature of 400 to 600° C.; in the cation adsorption, the cation is selected from NH4 + 、Ag + , K + 、Cs + One or more of the following, the cation concentration is 1 to 5 mmol / g molecular sieve, the mass ratio of the cation solution volume to the molecular sieve is 2 to 10 ml / g, and the adsorption temperature is 50 to 80°C; the acid treatment is performed by selecting one or more of hydrochloric acid, nitric acid, fluorosilicic acid, ammonium fluoride, ammonium hexafluorosilicate, and ammonium bifluoride; The alkylation reaction conditions are as follows: temperature 70-200° C., pressure 2-4 MPa, benzene-olefin molar ratio 4:1-60:1, feed olefin space velocity 0.3-3 h -1 .

2. The reaction method according to claim 1, wherein The alkylation reaction conditions are such that the contacting is carried out in the liquid phase.

3. The reaction method according to claim 1, wherein The substantially linear olefin has 8 to 15 carbon atoms.

4. The reaction method according to claim 1, wherein The proportion of the medium-strong acid to the total acid is 40-60%.

5. The reaction method according to claim 1, wherein The molecular sieve is Y.

6. The reaction method according to claim 1, wherein The mesopore volume of the molecular sieve accounts for 17% to 25% of the total pore volume.

7. The reaction method according to claim 1, wherein The molecular sieve and the heat-resistant inorganic oxide have a weight ratio of 99:1 to 20:80 on a dry basis.

8. The reaction method according to claim 1, wherein The molecular sieve and the heat-resistant inorganic oxide have a weight ratio of 95:5 to 25:75 on a dry basis.

9. The reaction method according to claim 1, wherein The molecular sieve and the heat-resistant inorganic oxide are in a weight ratio of 90:10 to 50:50 on a dry basis.

10. The reaction method according to any one of claims 1, 7 to 9, wherein: The heat-resistant inorganic oxide is selected from at least one of alumina, zirconia, silica and titania.

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