Method for preparing methyl tert-butyl ether and n-alkanes

Abstract

The invention relates to the field of catalytic dehydrogenation, and discloses a method for preparing methyl tert-butyl ether and n-alkanes, which comprises the following steps: (1) carrying out catalytic dehydrogenation reaction on a first C4 isoparaffin material flow to obtain a dehydrogenation effluent; (2) the dehydrogenation effluent is subjected to an etherification reaction, and a mixed material flow containing C4 isoparaffin and a methyl tert-butyl ether compound is obtained; (3) carrying out first separation on the mixed material flow to obtain a methyl tert-butyl ether product material flow and a second C4 isoparaffin material flow; and (4) carrying out a normalizing reaction on the second C4 isoparaffin material flow to obtain a normalizing reaction effluent. According to the method, light alkane dehydrogenation and normalizing technologies are combined, a set of circulation and separation process can be shared, on one hand, the circulation amount of light alkane is reduced, the energy consumption of the device is effectively reduced, on the other hand, a new product n-alkane is obtained, and the product structure is optimized.

Description

Technical Field

[0001] The invention relates to the field of catalytic dehydrogenation, and in particular to a method for preparing methyl tert-butyl ether and normal alkanes. Background Art

[0002] Methyl tert-butyl ether (MTBE) is an important chemical used as a gasoline additive and solvent, usually produced from methanol and isobutylene; among them, isobutylene is produced by dehydrogenation of C4 isoparaffins. In recent years, due to the slowdown in the promotion of ethanol gasoline and the continuous rise in the propylene oxide market, the MTBE market has heated up rapidly and has received widespread attention in the industry.

[0003] In addition, alkane normalization technology can effectively improve the utilization rate of low-carbon alkane resources and convert isomeric alkanes into normal alkanes. On the one hand, it can be used as one of the raw materials for steam cracking to effectively increase the yield of ethylene and propylene; on the other hand, it can be used to prepare maleic anhydride through the n-butane oxidation method to produce a series of chemical products such as calcium carbonate modification additives, foam-free soap detergents, water-based lubricant rust inhibitors and polymer resins.

[0004] CN201880087203.5 discloses a method for producing MTBE and alkylate. The method comprises delivering a hydrocarbon feed stream containing C4 hydrocarbons to a dehydrogenation unit to generate a dehydrogenation effluent containing C4 olefins; delivering the dehydrogenation effluent to an MTBE unit to provide a mixed stream containing C4 olefins and MTBE; separating the mixed stream to provide an MTBE product stream and a fractionator overhead stream containing olefins, and delivering the fractionator overhead stream to an alkylation unit to produce an alkylation product stream containing alkylate.

[0005] CN201410124540.0 discloses a method for preparing MTBE or isobutylene from mixed C4 alkanes, comprising the following steps: (1) first stage hydrogenation: to remove unsaturated hydrocarbons in the mixed C4 alkanes; (2) second stage hydrogenation: to remove impurities of sulfur and / or nitrogen in the mixed C4 raw material; (3) dehydrogenation: dehydrogenating the mixed C4 into normal butene and isobutylene; (4) isomerization: passing the dehydrogenation product into an isomerization device to isomerize the normal butene therein into isobutylene; (5) etherification: passing the isomerization product into an etherification device, wherein the isobutylene therein reacts with methanol to generate the MTBE. According to this method, the comprehensive utilization rate of C4 alkanes and the yield of MTBE can be improved.

[0006] CN201210189762.1 relates to a method for preparing butadiene from normal alkanes, the method comprising the following steps: (1) in the presence of a dehydrogenation catalyst, subjecting the normal alkanes to a dehydrogenation reaction to obtain a hydrocarbon mixture containing olefins; (2) in the presence of a cyclization catalyst, subjecting the hydrocarbon mixture containing olefins to a cyclization reaction to obtain a hydrocarbon mixture containing six-membered rings; (3) in the presence of a hydrogenation catalyst, subjecting the hydrocarbon mixture containing six-membered rings to a hydrogenation reaction to obtain a hydrocarbon mixture containing cyclohexane and / or alkylcyclohexane; (4) subjecting the hydrocarbon mixture containing cyclohexane and / or alkylcyclohexane to a steam cracking reaction as at least part of the cracking raw material. The method for preparing butadiene from normal alkanes can obtain a higher butadiene yield, and a lower methane yield, so that the cold box energy consumption in the cracking gas separation process is reduced.

[0007] US14 / 278040 discloses a method for producing butadiene by dehydrogenation of n-butane, comprising the following steps: (1) conveying a stream containing n-butane to a dehydrogenation reactor to produce a dehydrogenated product stream containing n-butane and butenes; (2) separating olefins and alkanes in the dehydrogenated product stream; (3) conveying the olefin stream to an oxidative dehydrogenation reactor to produce a product stream containing butadiene; and (4) returning the alkane stream to the dehydrogenation reactor.

[0008] CN201210118253.X provides an embodiment of a method for preparing propylene from paraffins, the method comprising the following steps: (1) combining an effluent containing propylene and propane from a paraffin dehydrogenation reactor with a waste gas stream containing propane to form a combined effluent stream; (2) separating the combined effluent stream into a propylene product stream and a propane-rich recycle stream; (3) introducing the propane-rich recycle stream into a paraffin dehydrogenation reactor operated under dehydrogenation conditions to convert the propane in the propane-rich recycle stream into propylene.

[0009] CN201910833923.8 discloses a normalization technology, a method for preparing butene-2 ​​from isobutylene, comprising: (1) feeding isobutylene into a normalization unit to contact with a normalization catalyst to obtain a reaction product rich in normal butene; (2) feeding the normalization reaction product of step (1) into a butene double bond isomerization unit to contact with a double bond isomerization catalyst to cause a double bond isomerization reaction of butene-1 to convert butene-1 into butene-2; (3) feeding the butene double bond isomerization reaction product into a fractionation tower, discharging butene-2 ​​product from the side of the tower, discharging C5+ heavy components from the bottom of the tower, and returning the mixture of isobutylene and butene-1 discharged from the top of the tower to the normalization unit. This method can prepare butene-2 ​​from isobutylene, which is used to prepare high-octane alkylation oil, and provides an effective way to increase the value of isobutylene and MTBE.

[0010] Although the above technologies have made some progress in optimizing the dehydrogenation of low-carbon alkanes, methyl tert-butyl ether (MTBE) technology and other combined processes, there is no combined technology combined with normalization. Summary of the invention

[0011] The purpose of the present invention is to overcome the problem that in the prior art, the single-pass conversion rates of the dehydrogenation and normalization reactions of the alkanes are low, a large amount of unconverted alkanes need to be circulated to the dehydrogenation and normalization reactors for further reaction, which increases the energy consumption of the device. A method for preparing methyl tert-butyl ether and normal alkanes is provided. The method combines the dehydrogenation and normalization technologies of the low-carbon alkanes, can share a set of circulation and separation processes, and reduces the circulation volume and energy consumption of the device.

[0012] In order to achieve the above object, the present invention provides a method for preparing methyl tert-butyl ether and normal alkanes, which comprises the following steps:

[0013] (1) subjecting a first C4 isoparaffin stream to a catalytic dehydrogenation reaction to obtain a dehydrogenation effluent;

[0014] (2) subjecting the dehydrogenation effluent to an etherification reaction to obtain a mixed stream containing C4 isoparaffins and methyl tert-butyl ether compounds;

[0015] (3) subjecting the mixed stream to a first separation to obtain a methyl tert-butyl ether product stream and a second C4 isoparaffin stream;

[0016] (4) subjecting the second C4 isoparaffin stream to a normalization reaction to obtain a normalization reaction effluent.

[0017] Preferably, step (4) further comprises: subjecting the second C4 isoparaffin stream to hydrogenation treatment to obtain a normalization reaction feed stream, and then subjecting the normalization reaction to the hydrogenation reaction.

[0018] Preferably, the olefin content in the normalization reaction feed stream is less than 1000wppm, preferably 0-600wppm.

[0019] Preferably, the content of heavy components in the normalization reaction feed stream is less than 2% by mass, preferably 0-1% by mass.

[0020] Preferably, the water content in the normalization reaction feed stream is ≤5wppm.

[0021] Through the above technical solution, the beneficial effects obtained are as follows:

[0022] (1) The method provided by the present invention combines the technology of dehydrogenating low-carbon alkanes to produce methyl tert-butyl ether and normal alkanes, and can adopt a set of circulation and separation systems to obtain methyl tert-butyl ether and normal alkanes at the same time, thereby reducing the circulation amount of low-carbon alkanes, reducing the energy consumption of the device, and increasing the efficiency of the device;

[0023] (2) The method provided by the present invention utilizes normalization technology to convert unreacted low-carbon alkanes into high-value normal alkane products, thereby obtaining important chemical raw materials - normal alkanes, optimizing the product structure, and effectively improving the utilization rate of the device and the competitiveness of the device in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a schematic process flow diagram of an embodiment of the present invention;

[0025] Figure 2 It is a schematic process flow chart of the existing catalytic dehydrogenation to produce methyl tert-butyl ether;

[0026] Figure 3 It is a schematic process flow chart of the existing butane normalization.

[0027] Description of Reference Numerals

[0028] Figure 1 and Figure 2 :

[0029] 1-Normal isomer separation unit 2-Catalytic dehydrogenation reaction unit 3-MTBE unit

[0030] 4-Separation unit 5-Hydroprocessing unit 6-Normalization unit

[0031] 10-alkane feedstock stream 11-first C4 isoparaffin 12-heavy fraction stream

[0032] 13-dehydrogenation effluent 14-methanol raw material 15-containing C4 isoparaffins and methyl

[0033] Mixed stream of tert-butyl ether compounds

[0034] 16-light component logistics 17-second C4 isoparaffin logistics 18-methyl tert-butyl ether product logistics 19-Normalization reaction feed stream 21-Normalization reaction effluent 22-Normal alkane product stream

[0035] Figure 3 :

[0036] 8-Normalization unit Normalization unit 9-Normalization unit Normal isomerization 31-Isoparaffin feedstock

[0037] Meta-unit

[0038] 33-Mixed isoparaffin stream 35-Normalization unit reaction outflow 36-Isoparaffin circulating stream

[0039] 37-Normalization unit normal alkanes

[0040] Product Logistics DETAILED DESCRIPTION

[0041] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0042] The first aspect of the present invention provides a method for preparing methyl tert-butyl ether and normal alkanes, which comprises the following steps:

[0043] (1) subjecting a first C4 isoparaffin stream to a catalytic dehydrogenation reaction to obtain a dehydrogenation effluent;

[0044] (2) subjecting the dehydrogenation effluent to an etherification reaction to obtain a mixed stream containing C4 isoparaffins and methyl tert-butyl ether compounds;

[0045] (3) subjecting the mixed stream to a first separation to obtain a methyl tert-butyl ether product stream and a second C4 isoparaffin stream;

[0046] (4) subjecting the second C4 isoparaffin stream to a normalization reaction to obtain a normalization reaction effluent.

[0047] In the present invention, there is no special limitation on the "first" and "second", which are only used to distinguish materials or operations in different processes.

[0048] In the present invention, the technology of dehydrogenating low-carbon alkanes to produce methyl tert-butyl ether and normal alkanes is combined, and a set of circulation and separation systems can be used to simultaneously obtain methyl tert-butyl ether and normal alkanes, thereby reducing the circulation amount of low-carbon alkanes, effectively reducing the energy consumption of the device, and increasing the efficiency of the device. The existing normalization device has low normalization efficiency, low normal butane yield, and the isobutane conversion rate can only reach 30%, which increases the energy consumption of the device.

[0049] According to the present invention, there is no particular limitation on the source of the first C4 isoparaffin stream. Preferably, the first C4 isoparaffin stream is obtained by subjecting an alkane feed stream to normal isomerization separation in a normal isomerization separation unit.

[0050] In the present invention, preferably, the alkane feedstock stream is subjected to normal isomerization separation to obtain a first C4 isoalkane stream and C4 normal alkanes.

[0051] According to the present invention, preferably, the alkane feedstock stream can be mixed C4 alkanes, which are mixed C4 by-products obtained from at least one of a crude oil refining unit, a steam cracking unit, a catalytic cracking unit, a catalytic reforming unit and a C4 deep processing unit.

[0052] According to the present invention, preferably, the method further comprises sending the normalization reaction effluent into the normal isomerization separation unit for normal isomerization separation. In this preferred embodiment, the normalization reaction effluent and the alkane feedstock stream are subjected to normal isomerization separation in the normal isomerization separation unit, preferably obtaining a first C4 isoalkane stream and a normal alkane product stream and a heavy component stream. In the present invention, the heavy component stream is C5+ alkanes and / or olefins, which refers to alkanes and / or olefins having five and / or more carbon atoms.

[0053] In the present invention, preferably, when the normalization reaction effluent is fed to the normal-isomerization separation unit and mixed with the alkane feed stream, the feed mass ratio of the normalization reaction effluent to the alkane feed stream can be adaptively adjusted by those skilled in the art.

[0054] According to the present invention, preferably, the first C4 isoparaffin stream is sent to step (1) for catalytic dehydrogenation reaction. Through the above-mentioned reuse, the utilization rate of the device can be improved and the energy consumption of the device can be reduced.

[0055] In the present invention, the conditions for normal isomerization separation are conventional normal isomerization separation conditions in the art, and the product obtained by normal isomerization separation only needs to meet the reaction conditions of the next process flow. Preferably, the normal isomerization separation makes the isoparaffin content in the first C4 isoparaffin stream >99%.

[0056] According to the present invention, preferably, step (4) further comprises: subjecting the second C4 isoparaffin stream to hydrogenation treatment to obtain a normalization reaction feed stream, and then subjecting the normalization reaction to the hydrogenation treatment.

[0057] In the present invention, preferably, the hydroprocessing is carried out in a hydroprocessing unit, and the operating conditions of the hydroprocessing include: a reaction temperature of 20-150°C, a reaction pressure of 3-4.5 MPa, and a volume space velocity of 1-20 h -1 The preferred reaction temperature is 30-80°C, the reaction pressure is 3-4MPa, and the volume space velocity is 6-15h -1 .

[0058] According to the present invention, preferably, the heavies content in the normalization reaction feed stream is less than 2% by mass, preferably 0-1% by mass. Low heavies content in the normalization reaction feed stream helps to improve the isobutane conversion rate and n-butane selectivity in the normalization reaction.

[0059] According to the present invention, preferably, the content of olefins in the normalization reaction feed stream is less than 1000wppm, preferably 0-600wppm. The normalization reaction feed stream from which olefins and alkynes are removed is obtained after hydrogenation treatment, which helps to make the olefin content in the normalization reaction feed stream less than 1000wppm, reduce the influence of olefins and alkynes on the normalization reaction, and improve the yield of normal alkanes.

[0060] According to the present invention, preferably, the water content in the normalization reaction feed stream is ≤5wppm. In the present invention, the normalization reaction feed stream is dried to control the water content in the normalization reaction feed stream to ≤5wppm, which can reduce the influence of water in the normalization reaction and improve the yield of normal alkanes.

[0061] In the present invention, there is no particular limitation on the drying method, and those skilled in the art can adjust it according to the actual reaction situation. According to a preferred embodiment of the present invention, the drying can be carried out in a dryer.

[0062] In the present invention, preferably, the isobutane content in the normalization reaction feed stream is >98% by mass.

[0063] In the present invention, preferably, the catalytic dehydrogenation reaction is carried out in a catalytic dehydrogenation reaction unit in the presence of a catalytic dehydrogenation catalyst. The catalytic dehydrogenation catalyst is a conventional catalytic dehydrogenation catalyst in the art that can achieve a catalytic dehydrogenation effect, and is preferably selected from the Pt series and / or the Cr series.

[0064] In the present invention, preferably, the catalytic dehydrogenation reaction unit is composed of 2-6 dehydrogenation reactors operated in series, and a heating furnace is provided between each reactor; wherein the dehydrogenation reactor of the catalytic dehydrogenation reaction unit is selected from a combination of one or more reactors selected from moving bed, fixed bed and fluidized bed.

[0065] According to the present invention, preferably, in step (1), the reaction conditions of the catalytic dehydrogenation reaction include: reaction temperature of 450-550°C, reactor inlet pressure of 0.01-1MPa, hydrogen-to-hydrocarbon molar ratio of 0.1-10, weight hourly space velocity of 1-12h -1 Preferably, the reaction temperature is 470-510°C, the reactor inlet pressure is 0.01-0.1 MPa, the hydrogen-to-hydrocarbon molar ratio is 0.3-0.6, and the weight hourly space velocity is 2-4 h -1 .

[0066] In the present invention, the reaction pressure refers to the gauge pressure.

[0067] In the present invention, preferably, the dehydrogenation effluent contains at least one of C4 isoolefins, C4 isoparaffins, hydrogen, light components and heavy components.

[0068] In the present invention, the conditions of the etherification reaction are not particularly limited, and those skilled in the art can adjust them adaptively to obtain the product methyl tert-butyl ether. Preferably, the etherification reaction is carried out in an MTBE unit, and the conditions of the etherification reaction include: the raw materials include methanol and dehydrogenation effluent, the reaction temperature is 50-80°C, the reactor inlet pressure is 0.6-1MPa, the molar ratio of methanol to isobutylene in the dehydrogenation effluent is 1-1.05:1, and a mixed stream containing C4 isoparaffins and methyl tert-butyl ether compounds is obtained.

[0069] In the present invention, preferably, in step (3), the first separation of the mixed stream containing C4 isoparaffins and methyl tert-butyl ether compounds is carried out in a separation unit. The conditions of the first separation can be adaptively adjusted by those skilled in the art as needed to achieve the separation effect and remove the water generated by methanol conversion after the etherification reaction.

[0070] In the present invention, preferably, the product obtained by the first separation comprises a methyl tert-butyl ether product stream and a second C4 isoparaffin stream and optionally a light component stream. The light component stream is C3 - The alkanes and / or alkenes refer to alkanes and / or alkenes having 3 or less carbon atoms.

[0071] In the present invention, preferably, the purity of the methyl tert-butyl ether product obtained by the first separation is >99.5%, and the content of heavy components in the second isoparaffin stream is <2% by mass.

[0072] According to the present invention, preferably, the reaction conditions of the normalization reaction include: reaction temperature of 150-250°C, reaction pressure of 1-4 MPa, hydrogen-to-hydrocarbon molar ratio of 0.01-1, and weight hourly space velocity of 0.1-6 h -1 More preferably, the reaction temperature is 150-200°C, the reaction pressure is 2-4 MPa, the hydrogen-to-hydrocarbon molar ratio is 0.01-0.5, and the weight hourly space velocity is 0.1-3 h -1 .

[0073] In the present invention, preferably, the normalization reaction is carried out in a normalization unit, and the normalization unit comprises 1-3 normalization reactors.

[0074] In the present invention, preferably, the normalization reaction is carried out under the above conditions, the yield of the generated normal alkanes is high, and the energy consumption of the device can be effectively reduced.

[0075] In the present invention, the method further comprises passing the alkane feedstock stream through a pretreatment unit (not shown in the figure) to remove impurities such as sulfur, nitrogen and metals in the feedstock, and then entering the normal isomerization separation unit for separation. The pretreatment conditions are not particularly limited, as long as they can remove impurities in the feedstock, and those skilled in the art can make adaptive adjustments as needed.

[0076] In some embodiments of the present invention, according to Figure 1 In the process flow shown, the alkane feedstock stream 10 is pretreated and then enters the normal isomerization separation unit 1 for normal isomerization separation to obtain a first C4 isoalkane stream 11. The first C4 isoalkane stream 11 enters the catalytic dehydrogenation reaction unit 2, contacts with a catalytic dehydrogenation catalyst, and undergoes a catalytic dehydrogenation reaction to obtain a dehydrogenation effluent 13. The dehydrogenation effluent 13 is sent to the MTBE unit 3, mixed with the methanol feedstock stream 14 for etherification reaction to generate a mixed stream 15 containing C4 isoalkane and methyl tert-butyl ether compounds. The mixed stream 15 containing C4 isoalkane and methyl tert-butyl ether compounds enters the separation unit 4 for a first separation to obtain a light component stream 16, a methyl tert-butyl ether product stream 18 and a second C4 isoalkane stream 17.

[0077] The second C4 isoalkane flow 17 enters the hydroprocessing unit 5, and is hydrotreated to generate a normalization reaction feed flow 19. The normalization reaction feed flow 19 enters the normalization unit 6, and undergoes a normalization reaction to obtain a normalization reaction effluent 21. The normalization reaction effluent 21 is sent to the normal-isomerization separation unit 1, and is mixed with the supplemented alkane feed flow 10 to perform normal-isomerization separation to obtain the first C4 isoalkane flow 11, a normal-alkane product flow 22 and a heavy component flow 12. The first C4 isoalkane flow 11 enters the next process flow to continue the cycle.

[0078] According to the present invention, preferably, the normalization reaction is carried out in the presence of a normalization catalyst.

[0079] According to the present invention, preferably, the normalization catalyst comprises a composite carrier and a Group VIII metal in an amount of 0.001-2 mass % based on the carrier.

[0080] According to the present invention, preferably, the composite carrier contains zirconium, silicon, aluminum and sulfur, with zirconium oxide, silicon oxide, aluminum oxide and SO 3 According to calculation, the composite support comprises 30-60 mass % of zirconium oxide, 0.01-5 mass % of silicon oxide, 35-60 mass % of aluminum oxide and 1-5 mass % of SO 3 .

[0081] According to the present invention, preferably, the composite carrier comprises 40-57 mass % of zirconium oxide, 0.01-2 mass % of silicon oxide, 40-55 mass % of aluminum oxide and 2-4 mass % of SO 3 .

[0082] According to the present invention, preferably, the Group VIII metal is selected from at least one of palladium, platinum and nickel.

[0083] In the present invention, preferably, the normalization catalyst is SO 4 2- / ZrO 2 -Al 2 O 3 The catalyst of the system, using the above catalyst for normalization reaction, needs to ensure that no water exists during the reaction process, and further cooperates with the reaction conditions of the present invention, can significantly improve the efficiency of the normalization reaction, accelerate the process of preparing methyl tert-butyl ether and normal alkanes, and reduce the energy consumption of the device.

[0084] The present invention has no particular limitation on the preparation method of the normalization catalyst, and the preparation method can be carried out according to conventional techniques in the art.

[0085] The present invention will be described in detail below through examples and comparative examples. In the following examples and comparative examples, unless otherwise specified, the reagents and materials used can be obtained commercially;

[0086] Solid superacid isomerization catalyst RISO-C, purchased from Sinopec;

[0087] Catalytic dehydrogenation catalyst PST-100, purchased from Sinopec;

[0088] The contents of heavy components and olefins in the normalization reaction feed stream are measured by gas chromatography PONA method;

[0089] The water content in the normalization reaction feed stream is measured by an online water content analyzer.

[0090] Preparation example of normalization catalyst

[0091] (a) Preparation of SO 4 2- / ZrO 2 -Al 2 O 3 Carrier

[0092] Take 31.8g of zirconium hydroxide powder (zirconium oxide content 78.5% by mass, containing a small amount of silicon), grind it thoroughly and set aside. Add 50mL of 0.5mol / L sulfuric acid aqueous solution to a beaker, and then add 15mL of deionized water to make a solution. Pour the zirconium hydroxide powder into the solution and stir it continuously to mix it evenly, let it stand at room temperature for 3h, and then place it in an oven to dry at 60℃ for 12h and 120℃ for 12h. Grind the dried solid into a fine powder, then mix it evenly with 33.1g SB powder (aluminum oxide content 75% by mass), and then add 19.2mL of 5.0% by mass nitric acid aqueous solution to dissolve it. After kneading evenly, extrude it into strips, dry the wet strips at 120℃ for 10h, and calcine them at 680℃ for 4h to obtain SO 4 2- / ZrO 2 -Al 2 O 3 carrier.

[0093] (b) Preparation of Pt-SO 4 2- / ZrO 2 -Al 2 O 3 catalyst

[0094] Take 20.0 g of SO prepared in step (a) 4 2- / ZrO 2 -Al 2 O 3 The carrier was added into 10.0 g of an aqueous solution containing 0.04 g of chloroplatinic acid and 0.1 g of nitric acid, and impregnated at 25 ° C for 3 h. The impregnated solid was dried at 120 ° C for 10 h and calcined at 550 ° C for 4 h to obtain the catalyst Pt-SO 4 2- / ZrO 2 -Al 2 O 3 , recorded as catalyst A.

[0095] XRF data of normalized catalyst w / %

[0096]

[0097] Example 1

[0098] The reaction was carried out according to the following process flow

[0099] (1) An alkane feedstock stream 10 (a fresh mixed C4 feedstock stream, comprising: C4 normal alkane and C4 isoalkane in a mass ratio of 0.25:1) is sent to a pretreatment unit (not shown in the figure), and after removing impurities such as sulfur, nitrogen and metals in the feedstock, it enters a normal isomerization separation unit 1 for normal isomerization separation to obtain a first C4 isoalkane stream 11, wherein the isoalkane content in the first C4 isoalkane stream 11 is greater than 99%; the first C4 isoalkane stream 11 enters a catalytic dehydrogenation reaction unit 2, and contacts with a catalytic dehydrogenation catalyst PST-100 for catalytic dehydrogenation reaction, wherein the catalytic dehydrogenation reaction unit comprises four fixed bed reactors connected in series, wherein the reaction temperature of the catalytic dehydrogenation is 520°C, the reactor inlet pressure is 0.1 MPa, the hydrogen-to-hydrocarbon molar ratio is 0.5, and the weight hourly space velocity is 2.5 h -1 , to obtain a dehydrogenation effluent 13;

[0100] (2) sending the dehydrogenation effluent 13 to the MTBE unit 3, mixing with the methanol feed stream 14, and undergoing an etherification reaction. The etherification reaction conditions are: reaction temperature 55° C., pressure 0.8 MPa, and a molar ratio of methanol to isobutylene of 1.05:1, to generate a mixed stream 15 containing C4 isoparaffins and methyl tert-butyl ether compounds;

[0101] (3) The mixed stream 15 containing C4 isoparaffins and methyl tert-butyl ether compounds enters the separation unit 4 for a first separation to obtain a light component stream 16, a methyl tert-butyl ether product stream 18 and a second C4 isoparaffin stream 17;

[0102] (4-1) The second C4 isoparaffin stream 17 enters the hydroprocessing unit 5. The conditions for the hydroprocessing are: reaction temperature of 45°C, reactor inlet pressure of 3.8 MPa, hydrogen-to-hydrocarbon molar ratio of 0.5, and weight hourly space velocity of 8 h -1 , generating a normalization reaction feed stream 19, wherein the olefin content in the normalization reaction feed stream 19 is 470wppm, the water content in the normalization reaction feed stream 19 is 3.5wppm, and the heavy component content is 0.9% by mass;

[0103] (4-2) Normalization Reaction The feed stream 19 enters the normalization unit 6, which is equipped with a normalization reactor, and contacts with the catalyst A for normalization reaction. The reaction conditions are: reaction temperature of 180° C., reaction pressure of 3.5 MPa, hydrogen-to-hydrocarbon molar ratio of 0.5, and weight hourly space velocity of 1.5 h -1 , a normalization reaction effluent 21 is obtained, and the normalization reaction effluent 21 is sent to the normal isomerization separation unit 1, mixed with the supplementary alkane feedstock flow 10 to carry out a normal isomerization separation reaction, to obtain a first C4 isoalkane flow 11, a normal alkane product flow 22 and a heavy component flow 12.

[0104] Example 2

[0105] The reaction was carried out according to the process flow of Example 1, except that the water content in the normalization reaction feed stream 19 was 10 wppm.

[0106] Example 3

[0107] The reaction was carried out according to the process flow of Example 1, except that the water content in the normalization reaction feed stream 19 was 30 wppm.

[0108] Example 4

[0109] The reaction was carried out according to the process flow of Example 1, except that the olefin content in the normalization reaction feed stream 19 was 2400 wppm.

[0110] Example 5

[0111] The reaction was carried out according to the process flow of Example 1, except that the olefin content in the normalization reaction feed stream 19 was 5600 wppm.

[0112] Example 6

[0113] The reaction was carried out according to the process flow of Example 1, except that the content of heavy components in the normalization reaction feed stream 19 was 2.5 wt%.

[0114] Example 7

[0115] The reaction was carried out according to the process flow of Example 1, except that the content of heavy components in the normalization reaction feed stream 19 was 4 wt%.

[0116] Comparative Example 1

[0117] according to Figure 2 The existing MTBE process flow and Figure 3 The conventional butane normalization process is shown to prepare methyl tert-butyl ether and normal butane, and the reaction conditions of each unit are the same as those in Example 1.

[0118] (1) An alkane feedstock stream 10 (with the same composition as in Example 1) is fed to a pretreatment unit (not shown in the figure), and after impurities such as sulfur, nitrogen and metals in the feedstock are removed, the stream is fed to a normal isomerization separation unit 1 for normal isomerization separation to obtain a first C4 isoalkane stream 11. The first C4 isoalkane stream 11 is fed to a catalytic dehydrogenation reaction unit 2, and is contacted with a catalytic dehydrogenation catalyst to undergo a catalytic dehydrogenation reaction to obtain a dehydrogenation effluent 13;

[0119] (2) The dehydrogenation effluent 13 is sent to the MTBE unit 3 to undergo an etherification reaction with the methanol feed stream 14 to generate a mixed stream 15 containing C4 isoparaffins and methyl tert-butyl ether compounds.

[0120] (3) sending the mixed stream 15 containing C4 isoparaffins and methyl tert-butyl ether compounds to the separation unit 4 for first separation to obtain a light component stream 16, a methyl tert-butyl ether product stream 18 and a second C4 isoparaffin stream 17;

[0121] (4-1) The second C4 isoparaffin stream 17 enters the hydroprocessing unit 5 to generate a normalization reaction feed stream 19;

[0122] (4-2) The normalization reaction feed stream 19 is returned to the normal isomerization separation unit 1 for normal isomerization separation.

[0123] (5) An isoparaffin feedstock 31 (having the same composition as the normalization reaction feed stream 19) and an isoparaffin circulating stream 36 generate a mixed isoparaffin stream 33, which is fed to the normalization unit 8 of the normalization device and brought into contact with the catalyst RISO-C for a normalization reaction. The normalization reaction conditions are the same as those in Example 1 to obtain a normalization device reaction effluent 35. The normalization device reaction effluent 35 is fed to the normal-isomerization separation unit 9 of the normalization device to obtain an isoparaffin circulating stream 36 and a normalization device normal-paraffin product stream 37. The isoparaffin circulating stream 36 is fed to the normalization unit 8 of the normalization device for circulation.

[0124] The reaction conditions of each unit of the process flow of the embodiment and the comparative example are shown in Table 1.

[0125] Isoparaffin conversion rate = (isobutane content in the second C4 isoparaffin stream - isobutane content in the normal alkane product stream) / isobutane content in the second C4 isoparaffin stream × 100%;

[0126] Normal alkane yield = normal butane production in the normal alkane product stream / mass of the second C4 isoalkane stream × 100%.

[0127] Table 1

[0128]

[0129]

[0130] It can be seen from the results in Table 1 that the process flow of catalytic dehydrogenation and normalization reaction using the method of the embodiment of the present invention has a significantly higher n-butane yield and isobutane conversion rate than the process flow of Comparative Example 1, and the cycle energy consumption of the device is also significantly lower than that of Comparative Example 1.

[0131] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing methyl tert-butyl ether and normal alkanes, characterized in that: The following steps are involved: (1) subjecting a first C4 isoparaffin stream to a catalytic dehydrogenation reaction to obtain a dehydrogenation effluent; (2) subjecting the dehydrogenation effluent to an etherification reaction to obtain a mixed stream containing C4 isoparaffins and methyl tert-butyl ether compounds; (3) subjecting the mixed stream to a first separation to obtain a methyl tert-butyl ether product stream and a second C4 isoparaffin stream; (4) subjecting the second C4 isoparaffin stream to a normalization reaction to obtain a normalization reaction effluent.

2. The method according to claim 1, wherein: The first C4 isoparaffin stream is obtained by subjecting an alkane feed stream to normal isomerization separation in a normal isomerization separation unit; Preferably, the method further comprises sending the normalization reaction effluent into the normal isomerization separation unit for normal isomerization separation to obtain a first C4 isoparaffin stream, a normal alkane product stream and a heavy component stream.

3. The method according to claim 2, wherein: The first C4 isoparaffin stream is sent to step (1) for catalytic dehydrogenation reaction.

4. The method according to any one of claims 1 to 3, wherein: Step (4) further comprises: subjecting the second C4 isoparaffin stream to hydrogenation treatment to obtain a normalization reaction feed stream, and then subjecting the normalization reaction to the hydrogenation reaction; Preferably, the hydroprocessing conditions include: reaction temperature of 20-150°C, reaction pressure of 3-4.5 MPa, volume space velocity of 1-20 h -1 .

5. The method according to claim 4, wherein: The content of heavy components in the normalization reaction feed stream is less than 2% by mass, preferably 0-1% by mass.

6. The method according to claim 4 or 5, wherein: The olefin content in the normalization reaction feed stream is less than 1000wppm, preferably 0-600wppm; And / or, the water content in the normalization reaction feed stream is ≤5wppm.

7. The method according to any one of claims 1 to 6, wherein: In step (1), the reaction conditions of the catalytic dehydrogenation reaction include: The reaction temperature is 450-550°C, the reactor inlet pressure is 0.01-1MPa, the hydrogen-to-hydrocarbon molar ratio is 0.1-10, and the weight hourly space velocity is 1-12h -1 ; Preferably, the reaction temperature is 470-510°C, the reactor inlet pressure is 0.01-0.1 MPa, the hydrogen-to-hydrocarbon molar ratio is 0.3-0.6, and the weight hourly space velocity is 2-4 h -1 .

8. The method according to any one of claims 1 to 7, wherein: The reaction conditions of the normalization reaction include: The reaction temperature is 150-250℃, the reaction pressure is 1-4MPa, the hydrogen-to-hydrocarbon molar ratio is 0.01-1, and the weight hourly space velocity is 0.1-6h -1 ; Preferably, the reaction temperature is 150-200°C, the reaction pressure is 2-4 MPa, the hydrogen-to-hydrocarbon molar ratio is 0.01-0.5, and the weight hourly space velocity is 0.1-3 h -1 .

9. The method according to any one of claims 1 to 8, wherein: The normalization reaction is carried out in the presence of a normalization catalyst; Preferably, the normalization catalyst comprises a composite support and a Group VIII metal in an amount of 0.001-2 mass % based on the composite support.

10. The method according to claim 9, wherein: The composite carrier contains zirconium, silicon, aluminum and sulfur. Calculated by zirconium oxide, silicon oxide, aluminum oxide and SO3, the composite carrier includes 30-60 mass% of zirconium oxide, 0.01-5 mass% of silicon oxide, 35-60 mass% of aluminum oxide and 1-5 mass% of SO3; Further preferably, the composite support comprises 40-57 mass % of zirconium oxide, 0.01-2 mass % of silicon oxide, 40-55 mass % of aluminum oxide and 2-4 mass % of SO3; Preferably, the Group VIII metal is selected from at least one of palladium, platinum and nickel.

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