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CN117138518B - Use of SSZ-74 molecular sieve in adsorption separation of benzene and cyclohexane - Google Patents

Use of SSZ-74 molecular sieve in adsorption separation of benzene and cyclohexane

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Publication number
CN117138518B
CN117138518B CN202311102621.6A CN202311102621A CN117138518B CN 117138518 B CN117138518 B CN 117138518B CN 202311102621 A CN202311102621 A CN 202311102621A CN 117138518 B CN117138518 B CN 117138518B
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ssz
molecular sieve
benzene
cyclohexane
silicon
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CN117138518A (en
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马野
马延航
范亚奇
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ShanghaiTech University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/12—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers
    • C07C7/13—Purification; Separation; Use of additives by adsorption, i.e. purification or separation of hydrocarbons with the aid of solids, e.g. with ion-exchangers by molecular-sieve technique
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2601/00—Systems containing only non-condensed rings
    • C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
    • C07C2601/14—The ring being saturated

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  • Organic Chemistry (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Inorganic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Water Supply & Treatment (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)

Abstract

本发明公开SSZ‑74分子筛在吸附分离苯和环己烷中的用途。本发明选择具有‑SVR结构SSZ‑74分子筛为分离材料，利用特有的有序硅羟基以及其独特的多维弯折孔道结构，同时结合了孔道结构择型性的优势及硅羟基与苯中π键产生的相互作用的优势，通过SSZ‑74分子筛对苯和环己烷的穿透点不同，实现了苯和环己烷的分离，适用于工业化分离。This invention discloses the application of SSZ-74 molecular sieve in the adsorption and separation of benzene and cyclohexane. The invention selects SSZ-74 molecular sieve with a -SVR structure as the separation material, utilizing its unique ordered silanol groups and distinctive multidimensional tortuous pore structure. It combines the advantages of pore structure selectivity and the interaction between silanol groups and the π bonds in benzene. By leveraging the different penetration points of SSZ-74 molecular sieve for benzene and cyclohexane, the separation of benzene and cyclohexane is achieved, making it suitable for industrial-scale separation.

Description

Use of SSZ-74 molecular sieve in adsorption separation of benzene and cyclohexane
Technical Field
The invention belongs to the technical field of adsorption separation, and particularly relates to application of an SSZ-74 molecular sieve in adsorption separation of benzene and cyclohexane.
Background
Cyclohexane is an important chemical raw material, is widely used in the production of nylon, paint, drug intermediates and the like, and in recent years, the productivity of China in the related chemical field is gradually improved. In practical chemical production, cyclohexane is generally produced by hydrogenation of benzene as a reactant, and it is generally difficult to achieve complete conversion, resulting in products often containing cyclohexane together with unreacted benzene, and thus obtaining cyclohexane of high purity by removing residual benzene is also a very important ring in chemical production. However, the physical properties such as the solidification point, density and the like of benzene and cyclohexane, and the chemical properties such as the molecular size, chemical structure and the like are relatively similar, and more importantly, the boiling points of benzene are almost the same, wherein the boiling point of benzene is 80.1 ℃ and the boiling point of cyclohexane is 80.7 ℃, so that the liquid-liquid azeotropic separation mode which is common in industry and widely applied through reduced pressure distillation, rectification and extractive distillation is difficult to obtain high-purity cyclohexane at one time, and if the traditional separation mode is used, multiple separations are often needed, so that the purification cost is high and the product purity is difficult to ensure. It is a significant challenge to efficiently and simply separate and purify a mixture of benzene and cyclohexane.
Based on this background, designing or searching a new, efficient and low energy consumption way of separating benzene and cyclohexane has become the key to purifying cyclohexane in the industry. In recent years, with the rise of various novel crystalline and amorphous functional materials, many materials offer the possibility for solving some classical industrial problems due to the natural advantages of the materials, wherein the development of porous materials provides many new choices for adsorption separation of a plurality of important chemical raw materials.
Many porous materials are widely used to solve the industrial problems of hydrogen purification, alkyne separation, benzene and cyclohexane separation, and selective adsorption of xylene isomers due to their relatively high specific surface area and ordered pore distribution, and adjustable pore size, structure and internal environment, including zeolite molecular sieves, carbon molecular sieves, metal organic framework Materials (MOFs), covalent organic framework materials (COFs), porous Organic Polymers (POPs), porous organic cages (cages), and the like. In the benzene and cyclohexane separation process, currently used porous materials mainly comprise metal organic framework Materials (MOFs) and porous organic cages (cages), and adsorption separation is mainly realized by matching pore channel sizes with benzene or cyclohexane sizes, or separation of the two is realized by regulating and controlling interaction of ligands in the pore channels and benzene or cyclohexane to delay diffusion pore outlet speeds. Although these porous materials all exhibit superior adsorptive separation properties, their structure often contains dynamic chemical bonds with poor stability, which can easily cause the destruction of the material structure under acidic, alkaline, and hydrothermal caustic conditions, thereby affecting the separation performance of the material after cyclic regeneration. Meanwhile, the industrial application of the porous material in the field of benzene and cyclohexane adsorption separation is greatly limited due to the expensive synthesis cost.
Among the porous Materials, zeolite molecular sieve Materials have outstanding advantages in terms of preparation cost and stability, and have been shown to have excellent properties in hydrogen purification, olefin separation and the like (Nature Materials,2021,20,362-369; science,2020,368, 1002-1006), but few studies have been conducted so far on the separation of benzene and cyclohexane, and only theoretical simulation and adsorption experiments have involved some experimental assumptions, so that the selection of a zeolite molecular sieve suitable for the separation of benzene and cyclohexane is likely to provide a new idea suitable for industrial production for the industrial problem.
Disclosure of Invention
In view of the above-described drawbacks of the prior art, an object of the present invention is to provide an application of SSZ-74 molecular sieve in adsorption separation of benzene and cyclohexane, in order to solve the technical problems existing in the prior art.
In order to achieve the above purpose, the present invention adopts the following technical scheme.
The first aspect of the invention protects the use of SSZ-74 molecular sieves in the adsorptive separation of benzene and cyclohexane.
The invention selects SSZ-74 molecular sieve with-SVR structure as separating material, uses special ordered silicon hydroxyl and its unique multidimensional bending pore canal, separates benzene and cyclohexane by structure shape selective adsorption of the multidimensional bending pore canal, simultaneously separates benzene and cyclohexane by interaction generated by pi bond in the ordered silicon hydroxyl and benzene, and realizes benzene and cyclohexane separation by different penetration points of SSZ-74 molecular sieve to benzene and cyclohexane.
In the application of the invention, the SSZ-74 molecular sieve is selected from an all-silicon SSZ-74 molecular sieve or a heteroatom doped SSZ-74 molecular sieve.
The all-silicon SSZ-74 molecular sieve is composed of silicon oxide (SiO 2), and the heteroatom doped SSZ-74 molecular sieve is composed of silicon dioxide and heteroatom oxide.
Preferably, the SSZ-74 molecular sieve has a silicon to heteroatom ratio of not less than 20, based on the molar ratio of silicon dioxide to heteroatom oxide. More preferably, the ratio is 20 to 200.
Preferably, the heteroatom is selected from one or more of aluminium, titanium, boron and gallium.
More preferably, the heteroatom is aluminum, resulting in a silica-alumina SSZ-74 molecular sieve.
Further preferably, the silicon-aluminum SSZ-74 molecular sieve has a silicon-aluminum ratio of more than 20, or 20-200, or 50-120, or 20-60, or 100-140, or 120-200, or preferably 50-120, in terms of the molar ratio of SiO 2 to Al 2O3. In some embodiments, 100, 30.
More preferably, the heteroatom is titanium, resulting in a titanium silicalite SSZ-74 molecular sieve.
Further preferably, the silicon-titanium ratio in the titanium silicon SSZ-74 molecular sieve is greater than 50, or may be 50-200, or may be 50-100, based on the molar ratio of SiO 2 to TiO 2. In some embodiments, 100.
In the application of the invention, the SSZ-74 molecular sieve is obtained by heating SSZ-74 molecular sieve raw powder. Heating to remove water in the SSZ-74 molecular sieve, thereby achieving the purpose of activating the SSZ-74 molecular sieve.
Preferably, the temperature of the heating treatment is 30-400 ℃, or may be 30-200 ℃, or may be 80-350 ℃, or may be 220-400 ℃, or preferably 80-450 ℃ or 200-400 ℃. In some embodiments, 200 ℃ and 400 ℃.
Preferably, the heating treatment time is 0.1 to 24 hours, may be 0.1 to 5 hours, may be 4 to 15 hours, may be 12 to 24 hours, and is preferably 1 to 6 hours or 2 to 4 hours. In some embodiments, 2h.
Preferably, the atmosphere of the heating treatment is selected from one or more of vacuum, air, nitrogen, helium and argon.
Preferably, the heating treatment is performed by degassing or purging.
Preferably, the heating treatment is preceded by roasting to remove the template agent in the SSZ-74 molecular sieve raw powder. The method removes the template agent through roasting, so that the pore canal is smooth, the later adsorption of benzene is facilitated, and the water adsorbed by the SSZ-74 molecular sieve is removed through heating treatment and activation, so that competitive adsorption with benzene and cyclohexane is avoided.
More preferably, the method further comprises acid washing and silicon supplementing before roasting, wherein the acid washing is acid soaking treatment, the silicon supplementing is adding a silicon supplementing reagent, the acid can be organic acid or inorganic acid, the organic acid can be citric acid, 2, 4-dimethylbenzenesulfonic acid and 2, 4-dimethylbenzoic acid, the organic acid can be sulfuric acid, nitric acid and hydrochloric acid, the silicon supplementing reagent can be selected from tetraethyl orthosilicate, ammonium hexafluorosilicate and ethyl orthosilicate, and the Crystal Growth & Design 2023,23,3681-3693 can be referred to specifically.
More preferably, the baking temperature is 200-800 ℃, or 200-550 ℃, or 450-650 ℃, or 600-800 ℃, or preferably 400-800 ℃ or 500-600 ℃. In some embodiments, 550 ℃ and 600 ℃.
More preferably, the roasting time is 0.5 to 24 hours, may be 0.5 to 3 hours, may be 2 to 10 hours, may be 6 to 15 hours, may be 12 to 24 hours, and is preferably 2 to 8 hours or 4 to 6 hours. In some embodiments, 4h, 5h.
More preferably, the firing is performed in a protective atmosphere. Preferably, the protective atmosphere is selected from one or more of nitrogen, argon, oxygen, air and oxygen-argon mixture, such as oxygen, air and oxygen-argon mixture.
More preferably, the SSZ-74 molecular sieve raw powder is prepared by 1) reacting a silicon source, a template agent and a mineralizer in an aqueous solution to obtain a gel mixture, and 2) crystallizing the gel mixture to obtain the SSZ-74 molecular sieve raw powder.
More preferably, in 1), further comprising adding a heteroatom source. The heteroatom is selected from one or more of aluminum, titanium, boron and gallium. The heteroatom source is derived from an oxide or sodium oxide salt of a heteroatom. When the heteroatom is aluminum, from sodium metaaluminate, when the heteroatom is titanium, from tetrabutyl titanate, when the heteroatom is boron, from boric acid, and when the heteroatom is gallium, from gallium oxide.
More preferably, the silicon source is selected from one or more of white carbon black, silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate and silica gel.
More preferably, the template is selected from one of hexamethylene-1, 6-bis (N-methylpyrrolidinium) divalent cations, hexamethylene-1-trimethylammonium-6-N-methylpyrrolidinium divalent cations, and hexamethylene-1, 6-bis (dimethylethyl) divalent cations. The template agent is one of the divalent cation hydroxide and the halide. Specifically, for example, the hexamethylene-1, 6-bis (dimethylethyl) divalent cation compound is hexamethylene-1, 6-bis (dimethylethylammonium hydroxide).
The structural formula of the hexamethylene-1, 6-bis (N-methylpyrrolidinium) divalent cation is as follows:
the structural formula of the hexamethylene-1-trimethylammonium-6-N-methylpyrrolidinium divalent cation is as follows:
the structural formula of the hexamethylene-1, 6-bis (dimethylethyl) divalent cation is as follows:
further preferably, the alkali metal source is selected from one or more of sodium hydroxide, potassium hydroxide and cesium hydroxide.
Further preferably, the fluorine source is selected from one or both of hydrofluoric acid and ammonium fluoride.
More preferably, the crystallization temperature may be 120 to 160 ℃, 140 to 180 ℃, 160 to 200 ℃, 180 to 220 ℃, or 200 to 240 ℃. In some embodiments, 160 ℃.
More preferably, the crystallization time may be 24 to 100 hours, 96 to 168 hours, 154 to 236 hours, or 268 to 336 hours. In some embodiments, 168h.
The second aspect of the invention protects an adsorption separation method for benzene and cyclohexane, which adopts SSZ-74 molecular sieve to adsorb and separate the mixed gas of benzene and cyclohexane.
In the adsorption separation method, the temperature of adsorption separation is 20-100 ℃, can be 20-45 ℃, can be 30-65 ℃ and can be 55-100 ℃. In certain embodiments, at 25 ℃ or room temperature.
In the adsorption separation method, the volume ratio of benzene to cyclohexane is (1-99): 1-99. In some embodiments, 50:50, 10:50.
In the adsorption separation method, the adsorption separation condition is that the flow rate of the mixed gas is 0.1-100 sccm. Preferably, the flow rate is 1-50 sccm.
In the adsorption separation method, the load gas in the adsorption separation is one or more selected from nitrogen, helium, argon and air. Preferably, the negative carrier gas is helium.
Preferably, the flow rate ratio of benzene, cyclohexane and negative carrier gas is 1 (0.5-5) (30-60). The flow rates of the negative carrier gas, cyclohexane, benzene and the catalyst are in a ratio of 48:1:1 and 44:5:1.
In the adsorption separation method, the SSZ-74 molecular sieve is selected from an all-silicon SSZ-74 molecular sieve or a heteroatom doped SSZ-74 molecular sieve.
Preferably, the SSZ-74 molecular sieve is selected from an all-silicon SSZ-74 molecular sieve or a heteroatom-doped SSZ-74 molecular sieve. The all-silicon SSZ-74 molecular sieve is composed of silicon oxide (SiO 2), and the heteroatom doped SSZ-74 molecular sieve is composed of silicon dioxide and heteroatom oxide.
Preferably, the SSZ-74 molecular sieve has a silicon to heteroatom ratio of not less than 20, based on the molar ratio of silicon dioxide to heteroatom oxide. More preferably, the ratio is 20 to 200.
Preferably, the heteroatom is selected from one or more of aluminium, titanium, boron and gallium.
More preferably, the heteroatom is aluminum, resulting in a silica-alumina SSZ-74 molecular sieve. Further preferably, the silicon-aluminum SSZ-74 molecular sieve has a silicon-aluminum ratio of more than 20, or 20-200, or 50-120, or 20-60, or 100-140, or 120-200, or preferably 50-120, in terms of the molar ratio of SiO 2 to Al 2O3. In some embodiments, 100, 30.
More preferably, the heteroatom is titanium, resulting in a titanium silicalite SSZ-74 molecular sieve. Further preferably, the silicon-titanium ratio in the titanium silicon SSZ-74 molecular sieve is greater than 50, or may be 50-200, or may be 50-100, based on the molar ratio of SiO 2 to TiO 2. In some embodiments, 100.
In the adsorption separation method, the SSZ-74 molecular sieve is obtained by heating SSZ-74 molecular sieve raw powder. Heating to remove water in the SSZ-74 molecular sieve, thereby achieving the purpose of activating the SSZ-74 molecular sieve.
Preferably, the temperature of the heating treatment is 30-400 ℃, or may be 30-200 ℃, or may be 80-350 ℃, or may be 220-400 ℃, or preferably 80-450 ℃ or 200-400 ℃. In some embodiments, 200 ℃ and 400 ℃.
Preferably, the heating treatment time is 0.1 to 24 hours, may be 0.1 to 5 hours, may be 4 to 15 hours, may be 12 to 24 hours, and is preferably 1 to 6 hours or 2 to 4 hours. In some embodiments, 2h.
Preferably, the atmosphere of the heating treatment is selected from vacuum, air, nitrogen, helium, argon. More preferably, air.
Preferably, the heating treatment is performed by degassing or purging.
Preferably, the heating treatment is preceded by roasting to remove the template agent in the SSZ-74 molecular sieve raw powder. The method removes the template agent through roasting, so that the pore canal is smooth, the later adsorption of benzene is facilitated, and the water adsorbed by the SSZ-74 molecular sieve is removed through heating treatment and activation, so that competitive adsorption with benzene and cyclohexane is avoided.
More preferably, the method further comprises acid washing and silicon supplementing before roasting, wherein the acid washing is acid soaking treatment, the silicon supplementing is adding a silicon supplementing reagent, the acid can be organic acid or inorganic acid, the organic acid can be citric acid, 2, 4-dimethylbenzenesulfonic acid and 2, 4-dimethylbenzoic acid, the organic acid can be sulfuric acid, nitric acid and hydrochloric acid, the silicon supplementing reagent can be selected from tetraethyl orthosilicate, ammonium hexafluorosilicate and ethyl orthosilicate, and the Crystal Growth & Design 2023,23,3681-3693 can be referred to specifically.
More preferably, the baking temperature is 200-800 ℃, or 200-550 ℃, or 450-650 ℃, or 600-800 ℃, or preferably 400-800 ℃ or 500-600 ℃. In some embodiments, 550 ℃ and 600 ℃.
More preferably, the roasting time is 0.5 to 24 hours, may be 0.5 to 3 hours, may be 2 to 10 hours, may be 6 to 15 hours, may be 12 to 24 hours, and is preferably 2 to 8 hours or 4 to 6 hours. In some embodiments, 4h, 5h.
More preferably, the firing is performed in a protective atmosphere. Preferably, the protective atmosphere is selected from one or more of nitrogen, argon, oxygen, air and oxygen-argon mixture, such as oxygen, air and oxygen-argon mixture.
More preferably, the SSZ-74 molecular sieve raw powder is prepared by 1) reacting a silicon source, a template agent and a mineralizer in an aqueous solution to obtain a gel mixture, and 2) crystallizing the gel mixture to obtain the SSZ-74 molecular sieve raw powder.
Further preferably, in 1), further comprising adding a heteroatom source. The heteroatom is selected from one or more of aluminum, titanium, boron and gallium. The heteroatom source is derived from an oxide or sodium oxide salt of a heteroatom. When the heteroatom is aluminum, from sodium metaaluminate, when the heteroatom is titanium, from tetrabutyl titanate, when the heteroatom is boron, from boric acid, and when the heteroatom is gallium, from gallium oxide.
Further preferably, the silicon source is selected from one or more of white carbon black, silica sol, tetramethyl orthosilicate, tetraethyl orthosilicate and silica gel.
Further preferably, the template is selected from one of hexamethylene-1, 6-bis (N-methylpyrrolidinium) divalent cations, hexamethylene-1-trimethylammonium-6-N-methylpyrrolidinium divalent cations, and hexamethylene-1, 6-bis (dimethylethyl) divalent cations. The template agent is one of the divalent cation hydroxide and the halide. Specifically, for example, the hexamethylene-1, 6-bis (dimethylethyl) divalent cation compound is hexamethylene-1, 6-bis (dimethylethylammonium hydroxide).
Further preferably, the mineralizer is selected from an alkali metal source or a fluorine source. The alkali metal source is selected from one or more of sodium hydroxide, potassium hydroxide and cesium hydroxide. The fluorine source is selected from one or two of hydrofluoric acid and ammonium fluoride.
More preferably, the crystallization temperature may be 120 to 160 ℃, 140 to 180 ℃, 160 to 200 ℃, 180 to 220 ℃, or 200 to 240 ℃. In some embodiments, 160 ℃.
More preferably, the crystallization time may be 24 to 100 hours, 96 to 168 hours, 154 to 236 hours, or 268 to 336 hours. In some embodiments, 168h.
The adsorption separation method of benzene and cyclohexane is a novel separation mechanism of SSZ-74 molecular sieve which integrates pore canal structure and micropore internal environment, is different from the prior simple pore canal shape-selective separation mode, has the advantages of low preparation cost and high stability compared with other porous materials, and is a separation material of benzene and cyclohexane which is more suitable for industrial application.
Compared with the prior art, the invention has the following beneficial effects:
1) The SSZ-74 molecular sieve is used as an adsorption separation material, so that high-efficiency penetration separation of benzene and cyclohexane can be realized, the gap of the molecular sieve material in the field of benzene and cyclohexane adsorption separation is filled, and meanwhile, compared with the existing separation means of other porous materials, the SSZ-74 molecular sieve also has the natural advantages of low preparation cost, simple preparation mode and the like.
2) The invention utilizes SSZ-74 molecular sieve to adsorb and separate benzene and cyclohexane, combines the advantage of unique multidimensional bending pore canal of SSZ-74 on the shape selectivity of benzene and cyclohexane and the advantage of interaction of rich ordered silicon hydroxyl groups in the pore canal of SSZ-74 molecular sieve on pi bonds in benzene, thereby cooperatively realizing the separation of benzene and cyclohexane.
3) The adsorption separation method can realize the high-efficiency separation of benzene and cyclohexane at room temperature by adopting the SSZ-74 molecular sieve, and meanwhile, the SSZ-74 molecular sieve has excellent regeneration performance as an adsorption separation material due to the high stability of the SSZ-74 molecular sieve, and can be recycled for 20 times and still has high-efficiency separation capability on benzene and cyclohexane.
4) Benzene and cyclohexane are adsorbed and separated by SSZ-74 molecular sieve, the penetration point of benzene is at least 9min/g later than that of cyclohexane, and the penetration point of benzene is 3.14min/g or less later than that of cyclohexane when other molecular sieve is used for adsorption and separation.
Drawings
FIG. 1 shows a PXRD spectrum of a heat treated SSZ-74 molecular sieve according to example 1 of the present invention.
FIG. 2 shows a PXRD spectrum of a heat treated SSZ-74 molecular sieve according to example 2 of the present invention.
FIG. 3 shows a PXRD spectrum of a heat treated SSZ-74 molecular sieve according to example 3 of the present invention.
FIG. 4 shows a PXRD spectrum of a heat treated SSZ-74 molecular sieve according to example 4 of the present invention.
FIG. 5 shows a gas breakthrough suction chart for benzene and cyclohexane obtained in example 5 of the present invention using the SSZ-74 molecular sieve of example 1.
FIG. 6 shows a gas breakthrough suction chart for benzene and cyclohexane obtained in example 7 of the present invention using the SSZ-74 molecular sieve of example 2.
FIG. 7 shows a graph of the gas breakthrough of benzene and cyclohexane obtained in example 8 of the present invention using the SSZ-74 molecular sieve of example 3.
FIG. 8 shows a gas breakthrough suction chart for benzene and cyclohexane obtained in example 9 of the present invention using the SSZ-74 molecular sieve of example 4.
FIG. 9 shows a gas breakthrough suction chart of benzene and cyclohexane obtained after 1 regeneration of the SSZ-74 molecular sieve of example 6 in example 10 according to the invention.
FIG. 10 shows a gas breakthrough suction chart of benzene and cyclohexane obtained after 20 regenerations using the SSZ-74 molecular sieve of example 5 in example 11 of the present invention.
Detailed Description
Further advantages and effects of the present invention will become apparent to those skilled in the art from the disclosure of the present invention, which is described by the following specific examples.
Before further describing embodiments of the invention, it is to be understood that the scope of the invention is not limited to the specific embodiments described below, and that the terminology used in the examples of the invention is intended to be in the nature of specific embodiments and is not intended to be limiting of the scope of the invention. The test methods in the following examples, in which specific conditions are not noted, are generally conducted under conventional conditions or under conditions recommended by the respective manufacturers.
Where numerical ranges are provided in the examples, it is understood that unless otherwise stated herein, both endpoints of each numerical range and any number between the two endpoints are significant both in the numerical range. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition to the specific methods, devices, materials used in the embodiments, any methods, devices, and materials of the prior art similar or equivalent to those described in the embodiments of the present invention may be used to practice the present invention according to the knowledge of one skilled in the art and the description of the present invention.
The inventor discovers through long-term experimental study that the SSZ-74 molecular sieve can realize the efficient separation of benzene and cyclohexane. Compared with the porous separation material disclosed before, the SSZ-74 molecular sieve used by the invention has the advantages of lower preparation cost, better stability, simple preparation and suitability for industrial production.
In the invention, PXRD data are measured by a German Brookfield D8 advanced type X-ray diffractometer and are used for representing the crystal structure of a molecular sieve, and a gas permeation curve is obtained by testing a Bei Shide instrument BSD-MAB multicomponent competitive adsorption permeation curve analyzer and is used for representing the gas separation performance.
The technical scheme of the invention is further described below through specific examples.
In the following examples of the present application, the structural formula of the employed hexamethylene-1, 6-bis (dimethylethylammonium hydroxide) is as follows:
example 1
In this example 1, SSZ-74 molecular sieve raw powder with a silicon to aluminum ratio of 100 was used as a raw material, and heat treatment was performed, comprising the steps of:
The SSZ-74 molecular sieve raw powder is roasted for 4 hours at 550 ℃, and then is vacuum heated and deaerated for 2 hours at 200 ℃ to obtain the SSZ-74 molecular sieve.
The preparation method of the SSZ-74 molecular sieve raw powder with the silicon-aluminum ratio of 100 comprises the following steps:
1) Silica sol (40 wt% SiO 2), sodium metaaluminate, sodium hydroxide solid powder and hexamethylene-1, 6-bis (dimethylethyl ammonium hydroxide) are used as a silicon source, an aluminum source, a mineralizer and a template agent (template agent is named as R) respectively, and are mixed, and stirred at room temperature for overnight to obtain a gel mixture. Wherein, the mole number of SiO 2 is obtained by converting the mass of the silicon source according to the mole number of the silicon element, the mole number of Al 2O3 is obtained by converting the mass of the aluminum source according to the mole number of the Al element, and the mole ratio of the silicon source, the aluminum source, the mineralizer, the template agent and water (SiO 2：Al2O3：NaOH：R：H2 O=1.0:0.005:0.15:0.4:40) is 1.0:0.005:0.15:0.4:40.
2) And then transferring the mixture into a reaction kettle for crystallization for 168 hours at 160 ℃ and the rotating speed of 30rpm, and after the crystallization is finished, cooling, filtering and washing the crystallized product and drying the crystallized product at 80 ℃ to obtain the SSZ-74 molecular sieve raw powder.
The SSZ-74 molecular sieve after the heat treatment is subjected to PXRD characterization, and the result is shown in figure 1.
As shown in FIG. 1, the characterization result of PXRD shows that the SSZ-74 molecular sieve obtained under the roasting condition and the heating treatment condition has a characteristic diffraction peak of the molecular sieve with a-SVR structure, is a pure-SVR molecular sieve, and the micropore size of the crystal is distributed at 0.3-0.5 nm.
In summary, it has been demonstrated that high crystallinity of SSZ-74 molecular sieves can be maintained by the activation process of the present application.
Example 2
In this example 2, the SSZ-74 molecular sieve raw powder having a silica-alumina ratio of 100 obtained in example 1 was used as a raw material, and after baking, a heat treatment was performed, comprising the steps of:
The SSZ-74 molecular sieve raw powder is roasted for 5 hours at 600 ℃, and is vacuum heated and deaerated for 2 hours at 400 ℃ to obtain the SSZ-74 molecular sieve.
The heat-treated SSZ-74 molecular sieve was subjected to PXRD characterization, and the results are shown in FIG. 2.
As can be seen from FIG. 2, the result of the PXRD characterization shows that the SSZ-74 molecular sieve obtained under the roasting condition and the heating treatment condition has a characteristic diffraction peak of the molecular sieve with a-SVR structure, but has lower peak intensity, and is a pure molecular sieve with a-SVR structure, but has poor crystallinity, wherein the micropore size of the SSZ-74 molecular sieve is distributed at 0.3-0.5 nm.
Taken together, it has been demonstrated that the crystal structure of the SSZ-74 molecular sieve can be maintained by the activation process of the present application.
Example 3
In this example 3, all-silicon SSZ-74 molecular sieve raw powder is used as a raw material, and after roasting, the raw material is subjected to heat treatment, which comprises the following steps:
roasting the raw powder of the all-silicon SSZ-74 molecular sieve at 550 ℃ for 4 hours, and vacuum heating and degassing at 200 ℃ for 2 hours to obtain the SSZ-74 molecular sieve.
The preparation of the all-silicon SSZ-74 molecular sieve raw powder is as follows:
1) Silica sol (40 wt% SiO 2), sodium hydroxide solid powder and hexamethylene-1, 6-bis (dimethylethylammonium hydroxide) were used as a silicon source, a mineralizer and a template agent (template agent was named R), respectively, and were mixed, and stirred overnight at room temperature to obtain a gel mixture. Wherein the mole number of SiO 2 is obtained by converting the mass of the silicon source into the mole number of silicon element, and the mole ratio of the silicon source, the mineralizer, the template agent and water (SiO 2：NaOH：R：H2 O=1.0:0.1:0.4:40) is 1.0:0.1:0.4:40.
2) Transferring the gel mixture obtained in the step 1) into a reaction kettle, crystallizing for 168 hours at 160 ℃ and the rotating speed of 30rpm, and after crystallization, cooling, filtering, washing and drying the crystallized product at 80 ℃ to obtain the SSZ-74 molecular sieve.
The PXRD characterization of the heat-treated all-silicon SSZ-74 molecular sieve is carried out, and the result is shown in FIG. 4.
As can be seen from FIG. 3, the PXRD characterization result shows that the SSZ-74 molecular sieve obtained under the roasting condition and the heating treatment condition has a characteristic diffraction peak of the molecular sieve with the SVR structure, is a pure molecular sieve with the SVR structure, and the micropore size of the crystal is distributed at 0.3-0.5 nm.
In summary, it has been demonstrated that high crystallinity of SSZ-74 molecular sieves can be maintained by the activation process of the present application.
Example 4
In this example 4, SSZ-74 molecular sieve raw powder with a silica-alumina ratio of 30 was used as a raw material, and after calcination, a heat treatment was performed, comprising the steps of:
The SSZ-74 molecular sieve raw powder is roasted for 4 hours at 550 ℃ and is vacuum heated and deaerated for 2 hours at 200 ℃ to obtain the SSZ-74 molecular sieve.
The preparation method of the SSZ-74 molecular sieve raw powder with the silicon-aluminum ratio of 30 comprises the following steps:
1) Silica sol (40 wt% SiO 2), sodium metaaluminate, sodium hydroxide solid powder and hexamethylene-1, 6-bis (dimethylethyl ammonium hydroxide) are used as a silicon source, an aluminum source, a mineralizer and a template agent (template agent is named as R) respectively, and the mixture is stirred at room temperature for overnight to obtain a gel mixture. Wherein, the mole number of SiO 2 is obtained by the mass conversion of the silicon source according to the mole number of the silicon element, the mole number of Al 2O3 is obtained by the mass conversion of the aluminum source according to the mole number of the Al element, and the mole ratio of the silicon source, the aluminum source, the mineralizer, the template agent and water (SiO 2：Al2O3：NaOH：R：H2 O=1.0:0.017:0.15:0.4:40) is 1.0:0.017:0.15:0.4:40.
2) Adding SSZ-74 molecular sieve seed crystal, transferring to a reaction kettle, crystallizing for 168 hours at 160 ℃ and the rotating speed of 30rpm, cooling, filtering, washing and drying the crystallized product at 80 ℃ after crystallization, thus obtaining SSZ-74 molecular sieve raw powder. Wherein SSZ-74 molecular sieve seeds are the product of example 3, and the added amount of the seeds is 10% of the solid content of the gel mixture based on the solid content of the gel mixture.
The SSZ-74 molecular sieve after the heat treatment is subjected to PXRD characterization, and the result is shown in FIG. 3.
As can be seen from FIG. 4, the PXRD characterization result shows that the SSZ-74 molecular sieve obtained under the roasting condition and the heating treatment condition has a characteristic diffraction peak of the molecular sieve with the SVR structure, is a pure molecular sieve with the SVR structure, and the micropore size of the crystal is distributed at 0.3-0.5 nm.
In summary, it has been demonstrated that high crystallinity of SSZ-74 molecular sieves can be maintained by the activation process of the present application.
Example 5
In this example 5, titanium silicalite SSZ-74 molecular sieve was used as a raw material, and heat treatment was performed after calcination, comprising the steps of:
And (3) pickling titanium silicon SSZ-74 molecular sieve raw powder, supplementing silicon, roasting for 4 hours at 550 ℃, and carrying out vacuum heating and degassing for 2 hours at 200 ℃ to obtain the SSZ-74 molecular sieve. The acid washing and silicon supplementing is that 1g of SSZ-74 molecular sieve raw powder is mixed with 0.1g of tetraethyl orthosilicate and 10g of 1M aqueous solution of nitric acid, and then the mixture is subjected to hydrothermal treatment at 175 ℃ for 12 hours.
The SSZ-74 molecular sieve raw powder with the silicon-titanium ratio of 100 is prepared as follows:
1) Silica sol (40 wt% SiO 2), tetrabutyl titanate, sodium hydroxide solid powder and hexamethylene-1, 6-bis (dimethylethyl ammonium hydroxide) as a silicon source, a titanium source, a mineralizer and a template agent were mixed, and stirred overnight at room temperature to obtain a gel mixture. Wherein, the mole number of SiO 2 is obtained by the mass conversion of the silicon source according to the mole number of the silicon element, the mole number of TiO 2 is obtained by the mass conversion of the titanium source according to the mole number of the titanium element, and the mole ratio of the silicon source, the titanium source, the mineralizer, the template agent and water (SiO 2：TiO2：NaOH：R：H2 O=1.0:0.01:0.1:0.4:40) is 1.0:0.01:0.1:0.4:40.
2) Transferring the gel mixture obtained in the step 1) into a reaction kettle, crystallizing for 168 hours at 160 ℃ and the rotating speed of 30rpm, and after crystallization, cooling, filtering, washing and drying the crystallized product at 80 ℃ to obtain the titanium silicon SSZ-74 molecular sieve.
Example 6
In this example 6, the heat-treated SSZ-74 molecular sieve of example 1 was used as an adsorption separation material, and performance test was performed using a multicomponent competitive adsorption breakthrough curve analyzer.
The test conditions were 50:50 volume ratio of benzene (Benzene) to cyclohexane (Cylcohexane) in the mixture, 1sccm for the negative carrier gas, 48sccm for the helium, 50sccm for the total test, and 25 ℃ for the separation test.
SSZ-74 molecular sieves are arranged in a penetrating column of the multicomponent competitive adsorption penetrating curve analyzer, mixed gas flows in through an inlet of the analyzer, is adsorbed by the SSZ-74 molecular sieves, flows out from an outlet of the analyzer, and the penetrating time of benzene and cyclohexane, the selective adsorption quantity of the SSZ-74 molecular sieves on each component of the mixed gas and the like are measured by measuring the change of the concentration of benzene and cyclohexane in the gas at the outlet along with time.
The breakthrough curve analysis is a technology for analyzing material adsorption separation under dynamic flow condition, and the principle is that molecular sieves are loaded in a breakthrough column as adsorption separation materials, the adsorption separation materials are piled up into a bed layer with a certain height, the bed layer is static, mixed gas flows in through an inlet of an absorber, is adsorbed by the molecular sieves and flows out from an outlet, and the breakthrough time of components except carrier gas and the selective adsorption quantity of the molecular sieves on the components of the mixed gas are measured by measuring the concentration change of the components of the outlet gas along with time, namely, the breakthrough curve. Multicomponent competitive adsorption breakthrough curve analyzer breakthrough adsorption curve is the curve of the concentration of benzene and cyclohexane in the effluent gas over time as the gas stream passes through the molecular sieve.
A breakthrough suction plot of SSZ-74 molecular sieves was obtained and the results are shown in FIG. 5. The abscissa in the graph is the ratio t/g of time to adsorption mass, and the ordinate is C/C0 at time t (i.e., the ratio of the outlet concentration C to the inlet concentration C0, i.e., the relative concentration). The corresponding point of the breakthrough curve when the effluent concentration C reaches 5% of the initial concentration C0 as the adsorbate emerges from the molecular sieve within the breakthrough column is then referred to as the breakthrough point (breakthrough point).
From FIG. 5, it is seen that in the breakthrough adsorption separation, the breakthrough point of benzene occurs with a lag of at least 15min/g compared to cyclohexane, which demonstrates that it can achieve efficient separation of benzene and cyclohexane.
Example 7
In this example 7, the heat-treated SSZ-74 molecular sieve of example 2 was used as an adsorption separation material, and performance test was performed using a multicomponent competitive adsorption breakthrough curve analyzer.
The test conditions were 50:50 volume ratio of benzene to cyclohexane, helium as the negative carrier gas, 1sccm for both benzene and cyclohexane, 48sccm for helium, 50sccm for total test, and 25℃for separation test.
A breakthrough suction plot of SSZ-74 molecular sieves was obtained and the results are shown in FIG. 6.
As can be seen from FIG. 6, in the breakthrough adsorption separation, the occurrence time of benzene breakthrough was delayed by about 9min/g compared to cyclohexane, indicating that the separation performance was low if the crystallinity was deviated after the pretreatment.
Example 8
In this example 8, the heat-treated SSZ-74 molecular sieve of example 3 was used as an adsorption separation material, and performance test was performed using a multicomponent competitive adsorption breakthrough curve analyzer.
The test conditions were 50:50 volume ratio of benzene to cyclohexane, helium as the negative carrier gas, 1sccm for both benzene and cyclohexane, 48sccm for helium, 50sccm for total test, and 25℃for separation test.
The SSZ-74 molecular sieves obtained are shown in FIG. 7 as a breakthrough suction chart.
From FIG. 7, it is evident that in the breakthrough adsorption separation, the benzene breakthrough occurs with a lag of at least 15min/g compared to cyclohexane, demonstrating that it can achieve a high efficiency of separation.
Example 9
In this example 9, the heat-treated SSZ-74 molecular sieve of example 4 was used as an adsorption separation material, and performance test was performed using a multicomponent competitive adsorption breakthrough curve analyzer.
The test conditions are that the volume ratio of benzene to cyclohexane in the mixed gas is 50:50, the negative carrier gas is helium, the flow rates of the benzene and the cyclohexane are 1sccm, the flow rate of the helium is 48sccm, the total test flow rate is 50sccm, and the separation test temperature is 25 ℃.
The SSZ-74 molecular sieves obtained are shown in the pierced drawings and the results are shown in FIG. 8.
From FIG. 8, it is evident that in the breakthrough adsorption separation, the benzene breakthrough occurs with a lag of at least 15min/g compared to cyclohexane, demonstrating that it can achieve a high efficiency of separation.
Example 10
In this example 10, the SSZ-74 molecular sieve of example 6 after adsorption separation of benzene and cyclohexane was used as an adsorption separation material, and regeneration was completed after heating at 400℃for 4 hours, after which performance test was performed using a multicomponent competitive adsorption breakthrough curve analyzer.
The test conditions are that the volume ratio of benzene to cyclohexane in the mixed gas is 50:50, the negative carrier gas is helium, the flow rates of the benzene and the cyclohexane are 1sccm, the flow rate of the helium is 48sccm, the flow rate of the total test is 50sccm, and the temperature of the separation test is 25 ℃.
The SSZ-74 molecular sieves obtained are shown in the pierced drawings and the results are shown in FIG. 9.
From FIG. 9, it is evident that in the breakthrough adsorption separation, the benzene breakthrough occurs at a time lag of about 15min/g compared to cyclohexane, demonstrating that it can achieve a high efficiency separation after 2 regenerations.
Example 11
In this example 11, the SSZ-74 molecular sieve of example 5 after adsorption separation of benzene and cyclohexane was used as an adsorption separation material, and after heating at 400 ℃ for 4 hours, regeneration was completed, and after repeating the regeneration-adsorption-regeneration 19 times, performance test was performed using a gas adsorption penetrator.
The test conditions are that the volume ratio of benzene to cyclohexane in the mixed gas is 50:50, the negative carrier gas is helium, the flow rates of the benzene and the cyclohexane are 1sccm, the flow rate of the helium is 48sccm, the flow rate of the total test is 50sccm, and the temperature of the separation test is 25 ℃.
The SSZ-74 molecular sieves obtained are shown in the pierced drawings and the results are shown in FIG. 10.
From FIG. 10, it is evident that in the breakthrough adsorption separation, the benzene breakthrough occurs at a time delay of approximately 15min/g compared to cyclohexane, demonstrating that it can still achieve a high efficiency separation after regeneration 20.
Example 12
The difference between this example 12 and example 6 is that the volume ratio of benzene and cyclohexane in the mixture was 10:50, the negative carrier gas was helium, the flow rates of benzene and cyclohexane were 1sccm and 5sccm, the flow rate of helium was 44sccm, the flow rate of the total test was 50sccm, and the temperature of the separation test was 25 ℃.
In the breakthrough adsorptive separation, the breakthrough point for benzene occurs at a time delay of approximately 15min/g compared to cyclohexane.
According to the application, LTA (4A) molecular sieves, BEA (Beta) molecular sieves, FER (ZSM-35) molecular sieves and TON (ZSM-22) molecular sieves are respectively obtained from commercial channels, and the performance test is carried out by adopting a gas adsorption penetrometer under the same conditions as in example 6, so that the hysteresis of the penetration point of benzene compared with the penetration point of cyclohexane is found to be 13s/g, 18.7s/g, 39.6s/g and 3.14min/g, which are far lower than 15min/g of the application, and the benzene and the cyclohexane cannot be separated, and the regeneration times of other molecular sieves are lower than the application.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (13)

  1. Use of ssz-74 molecular sieves in the adsorptive separation of benzene and cyclohexane.
  2. 2. The use according to claim 1, wherein the SSZ-74 molecular sieve is selected from an all-silicon SSZ-74 molecular sieve or a heteroatom-doped SSZ-74 molecular sieve;
    and/or the SSZ-74 molecular sieve is obtained by heating SSZ-74 molecular sieve raw powder.
  3. 3. The use according to claim 2, wherein the heteroatoms are selected from one or more of aluminum, titanium, boron and gallium;
    and/or roasting before the heating treatment to remove the template agent in the SSZ-74 molecular sieve raw powder;
    and/or the temperature of the heating treatment is 30-450 ℃;
    and/or the heating treatment time is 0.1-24 h;
    And/or the atmosphere of the heating treatment is selected from one or more of vacuum, air, nitrogen, helium and argon.
  4. 4. The use according to claim 3, wherein the SSZ-74 molecular sieve has a silicon to heteroatom ratio of not less than 20, based on the molar ratio of silicon dioxide to heteroatom oxide;
    And/or the roasting temperature is 200-800 ℃;
    And/or roasting for 3-5 hours;
    and/or, the method further comprises acid washing and silicon supplementing before roasting.
  5. 5. The use according to claim 4, wherein the SSZ-74 molecular sieve has a silicon to heteroatom ratio of 20 to 200, based on the molar ratio of silicon dioxide to heteroatom oxide.
  6. 6. The method of claim 2, wherein the SSZ-74 molecular sieve raw powder is prepared by 1) reacting a silicon source, a template agent and a mineralizer in an aqueous solution to obtain a gel mixture, and 2) crystallizing the gel mixture to obtain the SSZ-74 molecular sieve raw powder.
  7. 7. The use according to claim 6, wherein in 1) the templating agent is selected from one of hexamethylene-1, 6-bis (N-methylpyrrolidinium) divalent cations, hexamethylene-1-trimethylammonium-6-N-methylpyrrolidinium divalent cations, hexamethylene-1, 6-bis (dimethylethyl) divalent cations;
    And/or 1), the reaction further comprises adding a heteroatom source;
    And/or 1) wherein the mineralizer is selected from an alkali metal source or a fluorine source.
  8. 8. The use according to claim 7, wherein the alkali metal source is selected from one or more of sodium hydroxide, potassium hydroxide and cesium hydroxide;
    And/or the fluorine source is selected from one or two of hydrofluoric acid and ammonium fluoride.
  9. 9. A method for adsorption separation of benzene and cyclohexane is characterized in that SSZ-74 molecular sieve is adopted to adsorb and separate the mixed gas of benzene and cyclohexane.
  10. 10. The adsorption separation method according to claim 9, wherein the temperature of the adsorption separation is 20 to 100 ℃;
    and/or the volume ratio of benzene to cyclohexane is (1-99): 1-99;
    and/or the conditions of adsorption separation are that the flow rate of the mixed gas is 0.1-100 sccm;
    and/or the SSZ-74 molecular sieve is selected from an all-silicon SSZ-74 molecular sieve or a heteroatom-doped SSZ-74 molecular sieve;
    and/or the SSZ-74 molecular sieve is obtained by heating SSZ-74 molecular sieve raw powder.
  11. 11. The adsorptive separation process of claim 10, further comprising a negative carrier gas selected from one or more of nitrogen, helium, argon, and air;
    and/or the heteroatom is selected from one or more of aluminum, titanium, boron and gallium;
    and/or roasting before the heating treatment to remove the template agent in the SSZ-74 molecular sieve raw powder;
    and/or the temperature of the heating treatment is 30-450 ℃;
    and/or the heating treatment time is 0.1-24 h;
    and/or the atmosphere of the heating treatment is selected from one or more of vacuum, air, nitrogen, helium and argon;
    and/or the preparation method of the SSZ-74 molecular sieve raw powder comprises 1) reacting a silicon source, a template agent and a mineralizer in an aqueous solution to obtain a gel mixture, and 2) crystallizing the gel mixture to obtain the SSZ-74 molecular sieve raw powder.
  12. 12. The adsorptive separation process of claim 11 wherein the benzene, cyclohexane and negative carrier gas flow ratio is 1 (0.5-5): (30-60);
    And/or, the ratio of silicon to heteroatoms in the SSZ-74 molecular sieve is not less than 20, based on the molar ratio of silicon dioxide to heteroatom oxide;
    And/or the roasting temperature is 200-800 ℃;
    And/or roasting for 3-5 hours.
  13. 13. The adsorptive separation process of claim 12 wherein the SSZ-74 molecular sieve has a ratio of silicon to heteroatoms of 20 to 200, based on the molar ratio of silicon dioxide to heteroatom oxide.
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