A method for preparing methyl tert-butyl ether using a carbon four fraction as a raw material

Abstract

The application relates to a method for preparing methyl tert-butyl ether by taking a carbon four fraction as a raw material, characterized by comprising an etherification reaction: respectively preheating isobutylene-containing carbon four fraction and methanol to 27-42 DEG C, feeding the carbon four fraction into an etherification reactor at a space velocity of 1-3 h ‑1 -1.05-2.5 of the isobutylene to methanol ratio, and the methanol into the etherification reactor; under the action of a catalyst containing magnetic material, the isobutylene and the methanol generate methyl tert-butyl ether by etherification reaction under the conditions of a temperature of 60-110 DEG C, a pressure of 0.5-1.6 MPa and a magnetic field of 550-610 oe in the etherification reactor; the application has excellent selectivity for methyl tert-butyl ether, almost no isobutylene polymer and by-product methyl sec-butyl ether are generated, the service life of the catalyst and the system is prolonged, the product purity is improved, the catalyst activity is good, and the isobutylene conversion rate is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing methyl tert-butyl ether by using carbon four fraction as raw material. BACKGROUND

[0002] Methyl tert-butyl ether (MTBE) can not only be used as a high octane gasoline additive, but also is a raw material for cracking production of isobutene.

[0003] At present, methyl tert-butyl ether is generally produced by etherification reaction and catalytic synthesis of isobutene and methanol under the action of a catalyst. In industrial production, pure isobutene is difficult to obtain, so the raw material used is usually carbon four fraction, in which the content of isobutene is usually less than 30%, or even less than 10%, which leads to insufficient contact of isobutene with active centers of the catalyst, resulting in low conversion rate of isobutene. In addition, in the reaction process of isobutene and methanol, there are reactions of dimethyl ether generated by condensation of methanol, tert-butyl alcohol generated by hydration of isobutene, dimeric isobutene generated by self-polymerization of isobutene, and even polymeric isobutene. When the raw material used is carbon four fraction, there is also the reaction of methyl sec-butyl ether generated by etherification of n-butene and methanol due to the presence of n-butene in the carbon four fraction. The occurrence of these side reactions seriously reduces the yield and purity of the product. In particular, methyl sec-butyl ether and methyl tert-butyl ether are isomers, and their boiling points are extremely close. Once methyl sec-butyl ether is generated, it is almost impossible to remove it from methyl tert-butyl ether product. Therefore, selecting a suitable catalyst and improving the selectivity of the catalyst are the key to improving the yield and purity of the product.

[0004] The catalysts that can be applied to the etherification of isobutene and methanol to produce MTBE at present are mainly divided into three categories: 1) macroporous cation exchange resin catalyst: compared with other catalysts, the catalytic activity of this catalyst is the best at low temperature. In addition, when C4 fraction is used as raw material, by controlling the reaction conditions, almost no by-product methyl sec-butyl ether or a very small amount of by-product methyl sec-butyl ether can be produced, and MTBE with purity meeting the application of chemical industry can be prepared. However, the catalyst has the following disadvantages: 1) the strength of the catalyst packing is low, and the catalyst is easy to collapse during use; 2) the catalyst has poor heat resistance, and the active groups are easy to fall off at high temperature, thereby affecting the service life of the catalyst; 3) although the selectivity of this catalyst is relatively good, the occurrence of methanol condensation side reaction, isobutene hydration side reaction and isobutene polymerization side reaction still exists, which not only leads to the reduction of product yield, but also the dimers and trimers produced by isobutene polymerization are easy to block the pores of the catalyst, thereby causing the bed temperature to exceed the working value, and the overtemperature of the bed temperature changes the use environment of the catalyst, thereby causing the deactivation of the catalyst and affecting the service life of the catalyst; 4) the waste catalyst cannot be regenerated and reused, resulting in waste of resources; 2) molecular sieve catalyst: for example, Hβ catalyst, zeolite catalyst and ZSM-5, etc. This kind of catalyst has good selectivity due to its water absorption and shape-selective catalysis, and almost no impurities such as tert-butyl alcohol, dimethyl ether and isobutene polymer are produced. However, the activity of the catalyst is poor, and a relatively high isobutene conversion rate can be obtained only at a high temperature of more than 100 degrees Celsius. At this temperature, when C4 fraction is used as raw material, the presence of n-butene will cause etherification reaction with methanol to generate a small amount of by-product methyl sec-butyl ether, which is almost impossible to separate and remove from methyl tert-butyl ether. Therefore, the MTBE prepared by using this kind of catalyst can only be used as a gasoline additive, and cannot be used as a raw material for producing other compounds. 3) solid acid or heteropoly acid catalyst: this kind of catalyst is usually applied to batch reaction. When it is used in fixed bed or expanded bed, the catalyst loss is serious. Therefore, it can be used in fixed bed or expanded bed only when it is loaded on porous materials such as activated carbon, and the activity of the catalyst is low, the conversion rate of isobutene is low, and the selectivity is also general. Not only isobutene polymer impurities will be produced to block the pores of the catalyst, but also by-product methyl sec-butyl ether will be produced when C4 fraction is used as raw material. Therefore, there is no mature solid acid or heteropoly acid catalyst that can be commercially applied at present. SUMMARY

[0005] The present application aims at overcoming the defects in the prior art, and provides a method for preparing methyl tert-butyl ether by using carbon four fraction as raw material, which has excellent selectivity for methyl tert-butyl ether, hardly produces isobutylene polymer and by-product methyl sec-butyl ether, prolongs the service life of the catalyst and the system, improves the product purity, and has good catalyst activity and high isobutylene conversion rate.

[0006] To achieve the above-mentioned object, the technical scheme adopted by the present application is as follows:

[0007] A method for preparing methyl tert-butyl ether by using carbon four fraction as raw material, comprising an etherification reaction: respectively preheating the carbon four fraction containing isobutylene and methanol to 27-42℃, then feeding them into an etherification reactor according to an olefin / alcohol ratio of 1.05-2.5 (preferably 1.05-1.2) and a carbon four fraction space velocity of 1-3h -1 (optimally 1-2h -1 ), so that the isobutylene and the methanol generate methyl tert-butyl ether under the action of a catalyst containing magnetic material at a temperature of 60-110℃, a pressure of 0.5-1.6MPa and a magnetic field of 550-610oe in the etherification reactor.

[0008] The catalyst containing magnetic material is one or several of an ion exchange resin catalyst containing magnetic material, a catalyst containing magnetic material and heteropoly acid or solid acid, and a molecular sieve catalyst modified by magnetic material.

[0009] The magnetic material adopts a strontium element magnetic material.

[0010] As a further technical scheme, the strontium element magnetic material adopts a strontium ferrite.

[0011] As a further technical scheme, after the etherification reaction is completed, separation and purification are further needed.

[0012] The separation and purification comprises: feeding the reaction product obtained in the etherification reaction into a rectifying tower or a catalytic rectifying tower, controlling the tower bottom temperature to be 128℃ and the tower top pressure to be 0.55MPa, performing rectification, collecting the tower bottom distillate and performing adsorption desulfurization to prepare methyl tert-butyl ether fine product; and performing water washing on the tower top distillate to remove methanol, thereby obtaining unreacted carbon four fraction.

[0013] As a further technical scheme, when the magnetic material catalyst adopts an ion exchange resin catalyst modified by magnetic material, the rectifying tower adopts a catalytic rectifying tower, a catalyst expanded bed is arranged in the catalytic rectifying tower, and the catalyst expanded bed adopts an ion exchange resin catalyst containing magnetic material.

[0014] While feeding the etherification reaction product into the catalytic rectifying tower, methanol also needs to be fed.

[0015] As a further technical solution, when the magnetic material catalyst uses an ion exchange resin catalyst containing a magnetic material, the reaction temperature in the etherification reactor is controlled at 65-75 DEG C, and the reaction pressure is 0.9-1.2 MPa.

[0016] As a further technical solution, the preparation method of the magnetic material modified ion exchange resin catalyst comprises the following steps:

[0017] Step a, the magnetic material, dodecyl benzene sulfonic acid is added to the butanol solution, and stirred uniformly to prepare a 20-30 wt% strontium ferrite suspension;

[0018] Step b, the Amberlyst 15 (A-15) type ion exchange resin is dried to constant weight, then the strontium ferrite suspension prepared in step a is added in a solid-liquid ratio of 1 g:2-3 mL, stirred for 5-8 h, then washed with ethanol for 3-8 times, and dried to constant weight at 90 DEG C under vacuum to obtain the magnetic material modified ion exchange resin catalyst.

[0019] As a further technical solution, when the magnetic material catalyst uses a catalyst containing a magnetic material and a heteropoly acid or a solid acid, the separation and purification uses a rectifying column.

[0020] As a further technical solution, when the magnetic material catalyst uses a catalyst containing a magnetic material and a heteropoly acid or a solid acid, the reaction temperature in the etherification reactor is controlled at 90-100 DEG C, and the reaction pressure is 1.0-1.2 MPa.

[0021] As a further technical solution, the catalyst containing a magnetic material and a heteropoly acid or a solid acid uses a H3O 40 PW 12 -ZrO2 magnetic ceramsite catalyst;

[0022] H3O 40 PW 12 -ZrO2 magnetic ceramsite catalyst, which is prepared by loading H3O 40 PW 12 -ZrO2 on porous magnetic ceramsite containing a strontium element magnetic material; and the loading method comprises the following steps:

[0023] Step A, loading ZrO2: ZrOCl2·8H2O is added to a 50% volume concentration ethanol solution to prepare a 0.1 mol / L ZrOCl2 solution, then porous magnetic ceramsite is added to the ZrOCl2 solution in a solid-liquid ratio of 1 g:7-9 mL, heated at 70 DEG C, and ammonia water is added dropwise under rapid stirring until the pH is 10, stirred for 50-70 min, then filtered, and the ceramsite is washed with deionized water until there is no Cl -After drying, the magnetic ceramic loaded with ZrO2 is obtained.

[0024] Step B, loading phosphotungstic acid: sodium tungstate and disodium hydrogen phosphate are mixed in a mass ratio of 6.25:1, and then dissolved in boiling water to prepare a 2 mol / L sodium tungstate solution. Then, the magnetic ceramic loaded with ZrO2 is added to the solution in a solid-liquid ratio of 1 g:7-9 mL, stirred for 10 min, and then 0.5-0.6 times the volume of concentrated hydrochloric acid is added dropwise under stirring. Stirring is continued for 1 h, and then the mixture is taken out, dried, washed with water for 3-5 times, dried again, and calcined at 300°C for 50-70 min to obtain the magnetic ceramic loaded with H3O 40 PW 12 -ZrO2.

[0025] As a further technical solution, a method for preparing methyl tert-butyl ether from a C4 fraction as a raw material comprises the following steps:

[0026] Step 1, etherification reaction: the C4 fraction containing isobutylene and methanol after water removal are preheated to 35°C, and then sent into an etherification reactor in an alcohol / olefin ratio of 1.05-2.5 (the alcohol / olefin ratio refers to the molar ratio of methanol to isobutylene being 1.05-2.5:1, and the alcohol / olefin ratio is preferably 1.05-1.5), and the C4 fraction is fed into the etherification reactor at a space velocity of 1-3 h -1 (1-2 h -1 ), under the action of a magnetic material modified ion exchange resin catalyst fixed bed or an expanded bed in the etherification reactor, methyl tert-butyl ether is generated at a temperature of 70°C, a pressure of 1.0-1.2 MPa, and a magnetic field of 550-610 oe, and a reaction product is obtained;

[0027] Step 2, catalytic distillation: the reaction product generated in step 2 and methanol are sent into a catalytic distillation column, the temperature at the bottom of the column is controlled at 128°C, and the pressure at the top of the column is 0.55 MPa. Unreacted isobutylene in the reaction product of step 2 and methanol continue to undergo etherification reaction to generate methyl tert-butyl ether under the action of a magnetic material modified ion exchange resin catalyst expanded bed. Meanwhile, in the stripping section of the catalytic distillation column, heavy components MTBE, unreacted C4 fraction and methanol are separated, the unreacted C4 fraction and methanol are distilled out from the top of the catalytic distillation column to obtain a top distillate; and the heavy component methyl tert-butyl ether is discharged from the bottom of the catalytic distillation column to obtain a crude methyl tert-butyl ether product;

[0028] Step 3, purification: the crude methyl tert-butyl ether product is introduced into an adsorption distillation column, and KIP212 adsorbent is used for adsorption desulfurization to obtain a fine methyl tert-butyl ether product; and the top distillate is washed with water to remove methanol, and an unreacted C4 fraction is obtained.

[0029] As a further technical solution, a method for preparing methyl tert-butyl ether from C4 fraction includes the following steps: Step 1, etherification reaction: After dehydrating the C4 fraction containing isobutylene with methanol and preheating it to 45°C, the methanol-to-isobutylene ratio is 1.05-2.5 (the methanol-to-isobutylene ratio of 1.05-2.5 refers to a molar ratio of methanol to isobutylene of 1.05-2.5:1) (the preferred methanol-to-isobutylene ratio is 1.05-1.5), and the space velocity of the C4 fraction is 1-3 h⁻¹. -1 (Preferred 1-2h) -1 The mixture is fed into an etherification reactor, where isobutylene and methanol react under a supporting H3O. 40 PW 12 Under the action of a fixed bed of magnetic ceramic catalyst of ZrO2, methyl tert-butyl ether is generated at a temperature of 90-100℃, a pressure of 1.1-1.3MPa, and a magnetic field of 550-610oe, and the reaction product is obtained.

[0030] Step 2, Distillation: The product generated in Step 1 is fed into a distillation column. The temperature at the bottom of the column is controlled at 128°C and the pressure at the top of the column is 0.55 MPa. Inside the distillation column, the heavy component MTBE is separated from the unreacted C4 fraction and methanol. The unreacted C4 fraction and methanol are distilled off from the top of the distillation column to obtain the overhead distillate. The heavy component methyl tert-butyl ether is discharged from the bottom of the distillation column to obtain crude methyl tert-butyl ether.

[0031] Step 3, Purification: The crude methyl tert-butyl ether is fed into an adsorption distillation column and desulfurized using KIP212 adsorbent to obtain refined methyl tert-butyl ether; the distillate from the top of the column is washed with water to remove methanol and obtain unreacted C4 fraction.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. This invention improves the selectivity of the catalyst by introducing strontium ferrite magnetic material into the catalyst and applying a magnetic field during the reaction process, thereby inhibiting the polymerization reaction of isobutylene, reducing the amount of isobutylene polymer produced, and extending the service life of the catalyst and the continuous operation time of the system.

[0034] 2. This invention uses porous magnetic ceramic particles containing strontium ferrite magnetic material to support H3O. 40 PW 12 -ZrO2 solid acid is used to prepare catalysts containing magnetic materials and heteropoly acids or solid acids. One method involves adding expanded graphite to porous magnetic ceramic particles and combining it with H3O. 40 PW 12 The loading process of ZrO2 improved H3O 40 PW 12 -ZrO2's load-bearing capacity reduces H3O 40PW 12 H3O 40 PW 12 The strontium ferrite magnetic material has the advantages of high magnetic permeability, high saturation magnetization, high coercive force, high magnetic energy product, and the like, and the H3O 40 PW 12 ZrO2, not only improves the reaction activity of the catalyst, so that the conversion rate of isobutene can reach more than 98% at a reaction temperature of 90-100 degrees Celsius, but also reduces the occurrence of side reactions between n-butene and methanol, improves the purity of the product, reduces the content of the byproduct methyl sec-butyl ether in the product, so that the prepared methyl tert-butyl ether product can not only be used as a gasoline additive, but also can be applied to chemical reactions.

[0035] 3、The porous magnetic ceramsite containing the strontium ferrite magnetic material is used to load H3O 40 PW 12 ZrO2 solid acid, to prepare a catalyst containing a magnetic material and a heteropoly acid or a solid acid, and the porous magnetic ceramsite used has high strength and can withstand high-temperature calcination, and can be regenerated and recovered. DETAILED DESCRIPTION

[0036] The technical solutions of the present application will be described below in conjunction with specific examples. Obviously, the described examples are part of the embodiments of the present application, rather than all the embodiments. Based on the examples in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] The raw materials used in the present application are commercially available unless otherwise specified.

[0038] In the present application:

[0039] 1) Strontium ferrite powder (1.3 microns): Shenzhen Xingkeyue Biological Technology Co., Ltd.;

[0040] 2) The preparation method of the porous magnetic ceramsite catalyst comprises the following steps:

[0041] Step 1, preparation of magnetic ceramsite:

[0042] The magnetic ceramsite is prepared from the following raw materials in parts by weight:

[0043] Pearlite 15 parts; silicon carbide 25 parts; zeolite powder (100-150 mesh) 13 parts; magnetic material strontium ferrite 13 parts; foaming agent N, N'-dimethyl-N, N' dinitrosophtalimide 10 parts, PVA solution 100 parts, expanded graphite 8 parts, pore-forming agent calcium carbonate 4 parts; dolomite glue 8 parts; in the present application, the PVA solution and the foaming agent are added for foaming treatment, which can form small closed bubbles in the magnetic ceramic granule blank, in the later calcination process, with the carbonization of PVA, small pores are formed (at this time, part of the pores are still in a closed state), then with the increase of the calcination temperature, the material enters the porcelainization state, and the pore-forming agent calcium carbonate decomposes at high temperature to release gas, and the gas breaks the previously closed bubbles in the release process, thereby forming a connected pore structure, the foaming technology and the pore-forming technology of the pore-forming agent are combined, which greatly improves the porosity of the magnetic ceramic granule, and the porosity is increased by more than 50-80% compared with the pore-forming technology of the pore-forming agent and the foaming technology of the foaming agent; the addition of expanded graphite can improve the H3O 40 PW 12 -ZrO2 load firmness, reduce H3O 40 PW 12 -ZrO2 shedding probability. In addition, the addition of dolomite glue improves the hardness of the foamed magnetic blank and reduces the material loss in the crushing process of the foamed magnetic blank.

[0044] Step 1-1, configure the magnetic ceramic slurry:

[0045] After weighing each raw material by weight parts, first mix the PVA solution and the foaming agent uniformly to prepare a PVA mixed solution; then mix the pearlite, silicon carbide, zeolite, magnetic material, expanded graphite, pore-forming agent and dolomite glue, grind for 45 min, then add the freshly prepared PVA mixed solution and continue to grind and disperse for 10 min to prepare the magnetic ceramic slurry;

[0046] Step 1-2, prepare the foamed magnetic ceramic blank: pour the magnetic ceramic slurry prepared in step 1-1 into a mold, stand for 50 min, then heat the mold at 150℃ for 80 min for foaming treatment, take out and demold after the material is completely dried to prepare the foamed magnetic ceramic blank;

[0047] Step 1-3, crushing and ball milling: crush the foamed magnetic ceramic blank into particles with a particle size of 3-4 mm with a crusher, then dry mill with a ball mill and pass through a 2-3 mm screen to obtain the ceramic granule blank;

[0048] Step 1-4, sintering, acid leaching: the ceramic blank is heated to 900-1100℃ in a muffle furnace for calcination for 2h, cooled to room temperature, then soaked in 3mol / L sulfuric acid for 30min, then washed with water to remove H+, dried to obtain the porous magnetic ceramic.

[0049] 3) Porous ceramic, the preparation method is same with the porous magnetic ceramic, the difference is that the magnetic material strontium ferrite is not added.

[0050] 4) The mass content of each substance in the isobutene-containing C4 fraction: isobutane 42.64%, n-butane 16.38%, trans-butene 11.54%, n-butene 10.14%, isobutene 9.33%, cis-butene 8.93%, C5 0.26%, 1,3-butadiene 0.15%, C3 0.22%, S 43.8mg / m 3 , and 0.41% of other substances.

[0051] The other raw materials used in the application are commercially available unless otherwise specified.

[0052] Example 1

[0053] A magnetic material modified ion exchange resin catalyst, the preparation method comprises the following steps:

[0054] Step a, the magnetic material and dodecyl benzene sulfonic acid are added into a butanol solution, stirred uniformly to prepare a 20-30wt% strontium ferrite suspension; the concentration of dodecyl benzene sulfonic acid in the strontium ferrite suspension is 1wt%;

[0055] Step b, the Amberlyst15(A-15) type ion exchange resin is vacuum dried at 90 degrees Celsius until constant weight, then the strontium ferrite suspension prepared in step a is added according to the solid-liquid ratio of 1g:2.5mL, stirred for 6.5h, then washed with ethanol for 6 times, vacuum dried at 90 degrees Celsius until constant weight to obtain the magnetic material modified ion exchange resin catalyst.

[0056] Example 2

[0057] A magnetic ceramic catalyst loaded with H3O 40 PW 12 -ZrO2, the preparation method comprises the following steps:

[0058] Step A, ZrO2 loading: ZrOCl2·8H2O is added into a 50% volume concentration ethanol solution to prepare a 0.1mol / L ZrOCl2 solution, then the porous magnetic ceramic is added into the ZrOCl2 solution according to the solid-liquid ratio of 1g:8mL, heated at 70℃ and ammonia water is added dropwise under rapid stirring until the pH is 10, stirred for 1h, then filtered, the ceramic is washed with deionized water until no Cl -After drying, the magnetic ceramic loaded with ZrO2 is obtained.

[0059] Step B, loading phosphotungstic acid: mix sodium tungstate and disodium hydrogen phosphate in a mass ratio of 6.25:1, and then dissolve them in 1500 mL of boiling water to prepare a 2 mol / L sodium tungstate solution. Then, load the magnetic ceramic with ZrO2 in the sodium tungstate solution at a solid-liquid ratio of 1 g:8 mL, stir for 10 min, and then drop 800 mL of concentrated hydrochloric acid under stirring. Continue stirring for 1 h, take out, dry, wash with water for 3-5 times, dry again, and then calcine at 300 degrees Celsius for 1 h to obtain the magnetic ceramic loaded with H3O 40 PW 12 -ZrO2.

[0060] Example 3

[0061] A magnetic ceramic loaded with H3O 40 PW 12 -ZrO2, and a preparation method thereof, comprising the following steps: 40 PW 12 -ZrO2.

[0062] Example 4

[0063] A magnetic ceramic loaded with H3O 40 PW 12 -ZrO2, and a preparation method thereof, comprising the following steps:

[0064] Step A, loading ZrO2: add ZrO2 and dodecyl benzene sulfonic acid into a 50% volume concentration ethanol solution to prepare a 0.1 mol / L ZrO2 suspension. Then, load the porous magnetic ceramic in the ZrO2 suspension at a solid-liquid ratio of 1 g:8 mL, stir for 1 h, filter, wash with deionized water for 3-5 times, dry, and then obtain the magnetic ceramic loaded with ZrO2.

[0065] Step B, loading phosphotungstic acid: load the porous magnetic ceramic in a 2 mol / L phosphotungstic acid solution at a solid-liquid ratio of 1 g:8 mL, dry, and then calcine at 300 degrees Celsius for 1 h to obtain the magnetic ceramic loaded with H3O 40 PW 12 -ZrO2.

[0066] Example 5

[0067] A magnetic ceramic loaded with H4[Si(W3O 10 )4]-ZrO2, and a preparation method thereof, comprising the following steps:

[0068] Step A, loading ZrO2: same as example 2;

[0069] Step B, loading silicotungstic acid: according to the solid-liquid ratio of 1 g:8 mL, the magnetic ceramsite loaded with ZrO2 was added into a 2 mol / L silicotungstic acid solution, and stirred for 10 min for adsorption, and then dried, calcined at 300℃ for 1 h to obtain the magnetic ceramsite catalyst loaded with H4[Si(W3O 10 )4]-ZrO2.

[0070] Example 6

[0071] A magnetic ceramsite catalyst loaded with H3O 40 PW 12 -SnO2, a preparation method thereof, comprising the following steps:

[0072] Step A, loading SnO2 catalyst: a mixed solution was prepared by mixing fatty alcohol polyoxyethylene ether and n-butanol according to the mass ratio of 2:1, and then a 0.3 mol / L SnCl4 solution was mixed with the mixed solution according to the volume ratio of 1:2, and stirred for 30 min; then according to the solid-liquid ratio of 1 g:8 mL, porous magnetic ceramsite was added into the solution, and stirring was continued for 10 min, and then 25% ammonia water was slowly added under stirring until pH=9, and stirring was continued for 1 h, and then aging was performed for 1 h, and then the solution was removed, and then the porous magnetic ceramsite was washed with deionized water until pH=7, and then the porous magnetic ceramsite was soaked and washed with anhydrous ethanol for 2 times, and then vacuum dried, and then impregnated with 3 mol / L sulfuric acid for 2 h, and then vacuum dried, calcined at 550℃ for 3 h, and then soaked and washed with deionized water for 2-3 times, and then dried to obtain the magnetic ceramsite loaded with SnO2;

[0073] Step B, loading silicotungstic acid: same as example 2; finally, the magnetic ceramsite catalyst loaded with H3O 40 PW 12 -SnO2 was prepared.

[0074] Comparative example 1

[0075] A magnetic ceramsite catalyst loaded with H3O 40 PW 12 , a preparation method thereof, comprising the following steps:

[0076] Sodium tungstate and disodium hydrogen phosphate were mixed according to the mass ratio of 6.25:1, and then dissolved in 1500 mL of boiling water to prepare a 2 mol / L sodium tungstate solution, and then according to the solid-liquid ratio of 1 g:8 mL, the magnetic ceramsite loaded with ZrO2 was added into the sodium tungstate solution, and stirred for 10 min, and then 800 mL of concentrated hydrochloric acid was added dropwise under stirring, and stirring was continued for 1 h, and then taken out, dried, washed with water for 3-5 times, and then dried again, and then calcined at 300℃ for 1 h to obtain the magnetic ceramsite catalyst loaded with H3O 40 PW 12 .

[0077] Comparative Example 2

[0078] A H3O 40 PW 12 A ceramic catalyst loaded with ZrO2, prepared in the same way as in Example 2, except that the porous magnetic ceramic of Example 2 was replaced by a porous ceramic which did not contain magnetic material.

[0079] Comparative Example 3

[0080] An ion exchange resin catalyst, Amberlyst 15 (A-15).

[0081] Comparative Example 4

[0082] A ZSM-5 molecular sieve catalyst was used.

[0083] Application Example 1

[0084] I. Test Method:

[0085] Methyl tert-butyl ether was synthesized using the following three processes;

[0086] 1. Process One:

[0087] A method for synthesizing methyl tert-butyl ether using a carbon four fraction and methanol as raw materials, comprising the following steps:

[0088] Step 1, Immobilized bed: 25 g of catalyst was loaded into a tubular fixed bed reactor to form a catalyst immobilized bed;

[0089] Step 2, Etherification reaction: The carbon four fraction containing isobutylene and methanol after water removal treatment were preheated to 35°C, then sent into the tubular fixed bed reactor at an alcohol / olefin ratio of 1.05 and a carbon four fraction space velocity of 1.5 h -1 -1.2 MPa, and a magnetic field of 580 oe. Methyl tert-butyl ether was generated from isobutylene and methanol under the action of the catalyst at a temperature of 70°C, a pressure of 1.1-1.2 MPa, and a magnetic field of 580 oe. The reaction product was collected for use.

[0090] 2. Process Two:

[0091] The same as Process One, except that the reaction temperature was 95 degrees Celsius.

[0092] 3. Process Three:

[0093] The same as Process One, except that the reaction temperature was 105 degrees Celsius.

[0094] 3. Process Four

[0095] The same as Process One, except that the alcohol / olefin ratio was 2.5 and the reaction temperature was 105 degrees Celsius.

[0096] II. Index detection

[0097] 1. Isobutylene conversion, MTBE yield and selectivity: After the system was stable, the molar amount of isobutylene fed and the residual amount of isobutylene after step 2 etherification reaction were detected every day, and the contents of MTBE and by-product MTBE in the reaction product were detected, the isobutylene conversion, the yield and selectivity of MTBE were calculated, and the content ratio M of MTBE and by-product MTBE in the reaction product was calculated. MTBE : M MSBE The average value of the first 3 days after the system was stable was taken as the final result, and the results are shown in Table 1.

[0098] Isobutylene conversion % = (isobutylene feed amount - residual amount of isobutylene in the reaction product) / isobutylene feed amount * 100%;

[0099] MTBE yield % = molar yield of MTBE / molar feed amount of isobutylene * 100%;

[0100] MTBE selectivity % = yield of MTBE / conversion of isobutylene;

[0101] 2. Catalyst life detection: The system was continuously operated, and the isobutylene conversion was detected every day. When the isobutylene conversion was reduced by more than 2% compared with the previous day, and the isobutylene conversion was reduced by more than 5% compared with the average value of the first 3 days after the system was stable, the catalyst needed to be replaced, and the continuous use time of the system, i.e. the life time of the catalyst, was recorded. The results are shown in Table 1.

[0102] Table 1

[0103]

[0104]

[0105] Note: - is not performed.

[0106] Application Examples 2-7: Optimization of reaction conditions

[0107] I. Test method:

[0108] The method for synthesizing MTBE from C4 fraction and methanol as raw materials comprises the following steps:

[0109] Step 1, immobilized bed: 25 g of catalyst prepared in Example 2 was loaded into a tubular fixed bed reactor to form a catalyst immobilized bed.

[0110] Step 2, etherification reaction: the isobutene-containing C4 fraction and methanol were respectively preheated to 45°C after water removal treatment, and then sent into a tubular fixed bed reactor at an alcohol / alkene ratio of 0.9-2.5 and a C4 fraction space velocity of 1.0-2.0 h -1 The isobutene and methanol generated methyl tert-butyl ether under the action of the catalyst at a temperature of 95°C, a pressure of 1.1-1.2 MPa, and a magnetic field of 550-600 oe in the tubular fixed bed reactor, and the reaction product was collected for standby use.

[0111] The reaction conditions of application examples 2-7 are shown in Table 2.

[0112] II. Index detection

[0113] Isobutene conversion, methyl tert-butyl ether yield, and selectivity: the method was the same as that of application example 1, and the results are shown in Table 2.

[0114] Table 2

[0115]

[0116]

[0117] Application example 8: industrial application of the catalyst of example 1

[0118] The method for synthesizing methyl tert-butyl ether from a C4 fraction and methanol as raw materials comprises the following steps:

[0119] Step 1, loading of fixed bed and expanded bed: the catalyst prepared in example 1 was loaded into an etherification reactor to form a catalyst fixed bed; and the catalyst prepared in example 1 was loaded into a catalytic distillation column to form a catalyst expanded bed.

[0120] Step 2, etherification reaction: the isobutene-containing C4 fraction and methanol were respectively preheated to 35°C after water removal treatment, and then sent into an etherification reactor at an alcohol / alkene ratio of 1.05 and a C4 fraction space velocity of 1.5 h -1 The isobutene and methanol generated methyl tert-butyl ether under the action of the catalyst at a temperature of 70°C, a pressure of 1.0-1.2 MPa, and a magnetic field of 580 oe in the etherification reactor,

[0121] Step 2, catalytic distillation: the product of step 2 and methanol are fed into a catalytic distillation column, the temperature at the bottom of the column is controlled at 128°C, the pressure at the top of the column is 0.55 MPa, the unreacted isobutene in the product of step 2 and methanol continue to react in the catalytic distillation column to form MTBE, at the same time, in the stripping section of the catalytic distillation column, the heavy component MTBE is separated from the unreacted C4 fraction and methanol, the unreacted C4 fraction and methanol are distilled out from the top of the catalytic distillation column to obtain a top distillate; the heavy component MTBE is discharged from the bottom of the catalytic distillation column to obtain a crude MTBE product;

[0122] Step 3, purification: the crude MTBE product is fed into an adsorption distillation column, KIP212 adsorbent is used for adsorption desulfurization to obtain a fine MTBE product; the top distillate is washed with water to remove methanol to obtain the unreacted C4 fraction.

[0123] After the system is continuously operated for 300 h, it is stopped, the obtained MTBE product is weighed, and the purity (the content of MTBE) and the content of the byproduct MTB are determined, and the total yield of MTBE is calculated;

[0124] The results are: the total yield of MTBE in this example is 98.64%, the purity of the prepared MTBE product is 99.46%, and the content of the byproduct MTB is 0.02%.

[0125] Application Example 9: industrial application of the catalyst prepared in Example 2

[0126] The method for synthesizing MTBE from a C4 fraction and methanol comprises the following steps:

[0127] Step 1, loading of the fixed bed: the catalyst prepared in Example 2 is loaded into an etherification reactor to form a catalyst fixed bed;

[0128] Step 2, etherification reaction: the C4 fraction containing isobutene and methanol after water removal are preheated to 45°C, and then fed into the etherification reactor at an alcohol / olefin ratio of 1.05 and a C4 fraction space velocity of 1.5 h -1 , in the etherification reactor, isobutene and methanol react under the action of the catalyst to form MTBE at a temperature of 95°C, a pressure of 1.1-1.3 MPa, and a magnetic field of 580 oe,

[0129] Step 3, distillation: the product of step 2 is fed into a distillation column, the temperature at the bottom of the column is controlled at 128°C, and the pressure at the top of the column is 0.55 MPa, in the distillation column, the heavy component MTBE is separated from the unreacted C4 fraction and methanol, the unreacted C4 fraction and methanol are distilled out from the top of the distillation column to obtain a top distillate; the heavy component MTBE is discharged from the bottom of the distillation column to obtain a crude MTBE product;

[0130] Step 3, purification: the crude methyl tert-butyl ether is fed into an adsorption distillation column, and KIP212 adsorbent is used for adsorption desulfurization to obtain fine methyl tert-butyl ether; the overhead distillate is washed with water to remove methanol, and the unreacted carbon four fraction is obtained.

[0131] After the system is continuously operated for 300 h, it is stopped, the obtained methyl tert-butyl ether product is weighed, and the purity (content of methyl tert-butyl ether) and the content of the byproduct methyl sec-butyl ether are determined, and the total yield of methyl tert-butyl ether is calculated;

[0132] The results are: the total yield of methyl tert-butyl ether in this example is 98.17%, the purity of the prepared methyl tert-butyl ether product is 99.37%, and the content of the byproduct methyl sec-butyl ether is 0.05%.

[0133] The above-described embodiments are only preferred embodiments of the present application, and are not an exhaustive list of the feasible implementations of the present application. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present application should be considered to be included in the protection scope of the claims of the present application.

Claims

1. A process for producing methyl tert-butyl ether from a carbon four fraction as a raw material, characterized by, The etherification reaction comprises: separately preheating the isobutylene-containing C4 fraction and methanol to 27-42℃, then sending them into an etherification reactor at an olefin to alcohol ratio of 1.05-2.5 and a C4 fraction space velocity of 1-3h -1 In the etherification reactor, the isobutylene and methanol are subjected to etherification reaction under the action of a catalyst containing magnetic material at a temperature of 60-110℃, a pressure of 0.5-1.6MPa, and a magnetic field of 550-610oe to generate methyl tert-butyl ether. Catalysts containing magnetic materials are magnetic material-modified ion exchange resin catalysts, supported H3O 40 PW 12 One or both of magnetic ceramic catalysts of -ZrO2; The magnetic material modified ion exchange resin catalyst is prepared by the following steps: Step a, adding the magnetic material and dodecyl benzene sulfonic acid into butanol solution, stirring to prepare 20-30wt% strontium ferrite suspension; Step b, drying the Amberlyst 15 type ion exchange resin to constant weight, then adding the strontium ferrite suspension prepared in step a according to the solid-liquid ratio of 1g:2-3mL, stirring for 5-8h, then washing with ethanol for 3-8 times, drying to constant weight at 90 degrees Celsius under vacuum to obtain the magnetic material modified ion exchange resin catalyst; said H3O 40 PW 12 magnetic ceramic catalyst of -ZrO2, which is prepared by loading H3O 40 PW 12 -ZrO2, said porous magnetic ceramic containing strontium element magnetic material; said strontium element magnetic material adopts strontium ferrite The loading method comprises the following steps: Step A, loading ZrO2: ZrOCl2.8H2O was added into 50% volume concentration of ethanol solution to make 0.1 mol / L ZrOCl2solution, then porous magnetic ceramsite was added into the ZrOCl2solution at the ratio of 1 g:7-9 mL, heated at 70°C and ammonia water was added dropwise under rapid stirring until pH was 10, stirred for 50-70 min, then filtered, and the ceramsite was washed with deionized water until no Cl - , then dried to obtain the magnetic ceramsite loaded with ZrO2; Step B, loading phosphotungstic acid: mixed sodium tungstate and disodium hydrogen phosphate in mass ratio of 6.25:1, dissolved in boiling water to prepare a 2 mol / L sodium tungstate solution, then added to the ZrO2-loaded magnetic ceramic in the ratio of 1 g:7-9 mL, stirred for 10 min, then added 0.5-0.6 times the volume of concentrated hydrochloric acid under stirring, continued to stir for 1 h, removed, dried, washed with water for 3-5 times, dried again, calcined at 300 degrees Celsius for 50-70 min to obtain H3O 40 PW 12 -ZrO2-loaded magnetic ceramic catalyst.

2. The method according to claim 1, wherein the C4 fraction is used as raw material to prepare MTBE, and the method comprises the following steps: After the etherification reaction is completed, separation and purification are further needed; The separation and purification comprises: feeding the reaction product obtained in the etherification reaction into a rectifying tower or a catalytic rectifying tower, controlling the tower bottom temperature to be 128 degrees Celsius and the tower top pressure to be 0.55MPa, performing rectification, collecting the tower bottom distillate and performing adsorption desulfurization to obtain MTBE product, and performing water washing on the tower top distillate to remove methanol and obtain unreacted C4 fraction.

3. The method according to claim 2, wherein the rectifying tower is a catalytic rectifying tower, and the catalytic rectifying tower is provided with a catalyst expanded bed, and the catalyst expanded bed is filled with the magnetic material containing ion exchange resin catalyst; When the magnetic material containing catalyst is the magnetic material modified ion exchange resin catalyst, the etherification reaction kettle is provided with a catalyst expanded bed filled with the magnetic material containing ion exchange resin catalyst.

4. The method according to claim 1, wherein when the magnetic material containing catalyst is the magnetic material modified ion exchange resin catalyst, the reaction temperature in the etherification reaction kettle is controlled to be 65-75 degrees Celsius, and the reaction pressure is controlled to be 0.9-1.2MPa.

5. The method according to claim 2, wherein the magnetic material containing catalyst is the magnetic material modified ion exchange resin catalyst.

6. The method according to claim 1, wherein the magnetic material containing catalyst is the magnetic material modified ion exchange resin catalyst. ​ When the magnetic material-containing catalyst is a supported H3O 40 PW 12 -ZrO2 magnetic ceramic catalyst, the separation and purification uses a rectifying column. ​ When the catalyst containing magnetic material adopts the supported H3O 40 PW 12 When the catalyst containing magnetic material adopts the magnetic ceramsite catalyst of -ZrO2, the reaction temperature in the etherification reactor is controlled at 90-100℃, and the reaction pressure is 1.0-1.2Mpa.

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