CN112745187B - Method for preparing cyclohexane by benzene hydrogenation - Google Patents
Method for preparing cyclohexane by benzene hydrogenation Download PDFInfo
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- CN112745187B CN112745187B CN201911038611.4A CN201911038611A CN112745187B CN 112745187 B CN112745187 B CN 112745187B CN 201911038611 A CN201911038611 A CN 201911038611A CN 112745187 B CN112745187 B CN 112745187B
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- C07—ORGANIC CHEMISTRY
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- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/02—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by hydrogenation
- C07C5/10—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by hydrogenation of aromatic six-membered rings
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/06—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing polymers
- B01J31/08—Ion-exchange resins
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- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/16—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes
- B01J31/18—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes containing nitrogen, phosphorus, arsenic or antimony as complexing atoms, e.g. in pyridine ligands, or in resonance therewith, e.g. in isocyanide ligands C=N-R or as complexed central atoms
- B01J31/1805—Catalysts comprising hydrides, coordination complexes or organic compounds containing coordination complexes containing nitrogen, phosphorus, arsenic or antimony as complexing atoms, e.g. in pyridine ligands, or in resonance therewith, e.g. in isocyanide ligands C=N-R or as complexed central atoms the ligands containing nitrogen
- B01J31/181—Cyclic ligands, including e.g. non-condensed polycyclic ligands, comprising at least one complexing nitrogen atom as ring member, e.g. pyridine
- B01J31/1815—Cyclic ligands, including e.g. non-condensed polycyclic ligands, comprising at least one complexing nitrogen atom as ring member, e.g. pyridine with more than one complexing nitrogen atom, e.g. bipyridyl, 2-aminopyridine
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- B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
- B01J2231/60—Reduction reactions, e.g. hydrogenation
- B01J2231/64—Reductions in general of organic substrates, e.g. hydride reductions or hydrogenations
- B01J2231/641—Hydrogenation of organic substrates, i.e. H2 or H-transfer hydrogenations, e.g. Fischer-Tropsch processes
- B01J2231/645—Hydrogenation of organic substrates, i.e. H2 or H-transfer hydrogenations, e.g. Fischer-Tropsch processes of C=C or C-C triple bonds
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- C07C2601/12—Systems containing only non-condensed rings with a six-membered ring
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Abstract
The invention belongs to the field of chemical industry, and particularly discloses a method for preparing cyclohexane by benzene hydrogenation, which is carried out in two serially connected reactors, wherein a first reactor is filled with a metal-polymer composite catalyst, and a second reactor is filled with a composite hydrogenation catalyst; the metal-polymer composite catalyst comprises a polyacid crosslinked polymer matrix and a metal active component platinum, wherein the polymer matrix is a polymer containing a nitrogen-containing heterocyclic side group; the composite hydrogenation catalyst comprises continuous phase carbon and dispersed phase Raney alloy particles, wherein the dispersed phase Raney alloy particles are uniformly or non-uniformly dispersed in the continuous phase carbon. The invention uses metal-macromolecule compound catalyst and compound hydrogenation catalyst to carry out hydrogenation successively, so that benzene is completely converted into cyclohexane.
Description
Technical Field
The invention belongs to the field of chemical industry, and particularly relates to a method for preparing cyclohexane by benzene hydrogenation.
Background
Cyclohexane is an important organic chemical intermediate and is widely applied to the production of nylon-6 and nylon-66. At present, more than 90% of cyclohexane is industrially prepared by benzene hydrogenation, the production process technology is mature, common catalysts comprise nickel series, platinum series, palladium series and the like, wherein the nickel-aluminum system catalyst has better activity and relatively low price and is widely applied to industrial devices. The nickel-aluminum system catalyst used in the industry at present has a narrow range of active temperature, benzene hydrogenation is an exothermic reaction, when heat transfer is in problem, a temperature runaway phenomenon is easy to occur, and the surface of the oxide-loaded Ni catalyst is easy to deposit carbon.
Patents for Ni-based catalysts for the hydrogenation of benzene have been reported for example: CN1546230 discloses a method for preparing a benzene hydrogenation catalyst of a mixture of nickel oxide and rare earth oxide by a coprecipitation method; CN1210759A discloses a method for preparing nickel-based benzene hydrogenation catalyst by sol-gel method; CN1082388C discloses a method for preparing a low-nickel-content benzene hydrogenation catalyst by adopting a sol-gel method.
There are also many patents reporting benzene hydrogenation noble metal catalysts, such as: CN1322923C discloses a platinum-series benzene hydrogenation catalyst; CNI02600888A discloses a noble metal Ru catalyst for benzene hydrogenation, the catalyst is added with one or two of auxiliary agents La, ce, fe, zn, cu, etc., the carrier is mesoporous molecular sieve MCM-41 modified by one or two of oxides ZrO2, znO and CuO; CN1457923 discloses a high-activity platinum catalyst for preparing cyclohexane by benzene hydrogenation, which comprises the following components in percentage by weight: 0.05 to 20 percent of Pt, 0.05 to 30 percent of auxiliary agent and the balance of carrier, wherein the preparation method comprises the steps of preparing a soluble platinum compound and an acid dipping auxiliary agent into a dipping solution by adopting a dipping-wet reduction method, wherein the concentration of Pt in the dipping solution is 0.01 to 50g Pt/100ml, dipping the carrier at 10 to 95 ℃, drying at 80 to 200 ℃, reducing the dried catalyst mother body by using a solution containing a reducing agent and having the concentration of 0.1 to 50wt percent, washing by using deionized water, drying, dipping by 0.05 to 30wt percent of alkali auxiliary agent, drying at 80 to 200 ℃, and roasting at 200 to 800 ℃ for 2 to 12 hours to prepare the catalyst, and the catalyst has higher activity and selectivity when being used for preparing cyclohexane by benzene hydrogenation.
As described above, most of the benzene hydrogenation catalysts in the prior art are inorganic supported catalysts, and most of the inorganic oxide carriers are alumina, silica, zirconia, magnesia, zinc oxide, activated carbon, or a composite thereof. The surface acidity of the inorganic carrier enables carbon deposition to be easily formed on the surface of the catalyst in the benzene hydrogenation reaction, reduces the activity of the catalyst and shortens the service life of the catalyst. In order to reduce carbon deposition, a basic inorganic auxiliary agent is usually added into the catalyst to reduce the acidity of the catalyst surface, but the method cannot completely solve the problem of carbon deposition.
Therefore, for preparing cyclohexane by benzene hydrogenation, a hydrogenation process method is developed, the problem of poor catalyst stability caused by easy carbon deposition on the surface of the catalyst can be solved, high-activity thorough hydrogenation can be realized, reaction temperature runaway can be avoided, and the method has important practical significance for the application of the benzene hydrogenation catalyst.
Disclosure of Invention
The invention aims to provide a method for preparing cyclohexane by benzene hydrogenation, which uses a metal-polymer composite catalyst and a composite hydrogenation catalyst to carry out hydrogenation sequentially so that benzene is completely converted into cyclohexane.
The invention provides a method for preparing cyclohexane by benzene hydrogenation, which is carried out in two reactors connected in series, wherein a first reactor is filled with a metal-polymer composite catalyst, and a second reactor is filled with a composite hydrogenation catalyst; the metal-polymer composite catalyst comprises a polyacid crosslinked polymer matrix and metal active component platinum, wherein the polymer matrix is a polymer containing a nitrogen-containing heterocyclic side group, a nitrogen atom in the nitrogen-containing heterocyclic side group has lone-pair electrons, and at least part of the metal active component platinum and the lone-pair electrons of the nitrogen atom form coordination bonds; the composite hydrogenation catalyst comprises continuous phase carbon and dispersed phase Raney alloy particles, wherein the dispersed phase Raney alloy particles are uniformly or non-uniformly dispersed in the continuous phase carbon, and the continuous phase carbon is obtained by carbonizing a carbonizable organic matter or a mixture thereof.
According to the invention, most of raw material benzene is converted into cyclohexane by the metal-polymer composite catalyst in the first-stage reactor, and then the benzene raw material is completely hydrogenated by the composite hydrogenation catalyst in the second reactor, so that the hydrogenation thoroughness in the benzene hydrogenation process is realized. Meanwhile, the metal-polymer composite catalyst utilizes a polymer material as a carrier, so that carbon deposition is not easy to occur, the activity is stable, the activity of the composite hydrogenation catalyst is high, hydrogenation is thorough, and the content of residual benzene is low, so that the stability of the reaction is kept in the hydrogenation process of benzene, and the risk of temperature runaway is avoided.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides a method for preparing cyclohexane by benzene hydrogenation, which is carried out in two reactors connected in series, wherein a first reactor is filled with a metal-polymer composite catalyst, and a second reactor is filled with a composite hydrogenation catalyst;
the metal-polymer composite catalyst comprises a polyacid crosslinked polymer matrix and a metal active component platinum, wherein the polymer matrix is a polymer containing a nitrogen-containing heterocyclic side group, nitrogen atoms in the nitrogen-containing heterocyclic side group have lone-pair electrons, and at least part of the metal active component platinum and the lone-pair electrons of the nitrogen atoms form coordination bonds;
the composite hydrogenation catalyst comprises continuous phase carbon and dispersed phase Raney alloy particles, wherein the dispersed phase Raney alloy particles are uniformly or non-uniformly dispersed in the continuous phase carbon, and the continuous phase carbon is obtained by carbonizing a carbonizable organic matter or a mixture thereof.
Firstly, converting most of raw material benzene into cyclohexane by using a metal-polymer composite catalyst in a first-stage reactor, and then completely hydrogenating the benzene raw material by using a composite hydrogenation catalyst in a second reactor, wherein preferably, the first-stage reactor is a slurry bed reactor, and the reaction temperature of the first-stage reactor is 50-120 ℃, preferably 80-100 ℃; the reaction pressure is 0.1-8.0 MPa, preferably 1.0-5 MPa; the liquid phase space velocity is 0.1 to 10 hours -1 Preferably 0.5 to 5 hours -1 (ii) a The feeding molar ratio of the raw material benzene to the hydrogen is 1:3 to 10;
the second-stage reactor is a fixed bed reactionThe reaction temperature of the second-stage reactor is 50-300 ℃, and preferably 100-200 ℃; the reaction pressure is 0.1-8.0 MPa, preferably 1.0-5 MPa; the liquid phase space velocity is 0.1 to 20 hours -1 Preferably 5 to 10 hours -1 。
Wherein, in the metal-polymer composite catalyst filled in the first-stage reactor, preferably, the polyacid crosslinked polymer matrix is a highly crosslinked, porous, composite carrier with a large specific surface area obtained by the polymer matrix under the coordination crosslinking action of polyacid. The composite carrier is coordinated with the metal active component to obtain the metal-polymer composite catalyst with uniform dispersion and firm load. Wherein, the content of the metal active component platinum in the metal-polymer composite catalyst is preferably 0.1 to 5wt%.
According to the present invention, the polybasic acid is an inorganic acid and/or an organic acid capable of dissociating two or more hydrogen ions, and specifically, at least one of sulfuric acid, phosphoric acid, citric acid, peroxymolybdic acid, and chloroplatinic acid is preferable.
The nitrogen atom in the polymer matrix of the composite catalyst has uncoordinated lone-pair electrons, and has coordination with the metal active component, so that the load stability of the metal active component is improved through the chemical bond effect. The nitrogen-containing heterocyclic side group contains a nitrogen atom with unpaired lone pair electrons, and the purpose can be achieved. Preferably, the pendant group containing the nitrogen-containing heterocyclic ring is imidazolyl and/or pyridyl, that is, the macromolecular matrix is a macromolecular polymer containing imidazolyl and/or pyridyl.
In the present invention, the main chain structure of the polymer matrix is not particularly limited, and it is preferable that the polymer monomer of the polymer matrix includes C containing an imidazole group and/or a pyridine group in view of the sufficiency of the site of the metal active component and steric hindrance of the group 2 -C 6 Olefin, the polymer matrix may be a homopolymer or a copolymer, as long as the polymerizable monomer includes C having an imidazole group and/or a pyridine group 2 -C 6 And (3) olefin.
The relative amounts of the components in the composite catalyst are not particularly limited, and the nitrogen atoms need to be crosslinked with the polyacid and positioned with the metal active component, so that the molar ratio of the polyacid to the nitrogen-containing heterocyclic side group contained in the polymer matrix is preferably 1 (4-50), and preferably 1 (4-20). Preferably, the molar ratio of the metal active component platinum to the nitrogen-containing heterocyclic side group contained in the polymer matrix is 1 (6-1500), and preferably 1 (6-1000).
The invention provides a preparation method of the metal-polymer composite catalyst, which comprises the following steps:
a. dissolving or dispersing the polymer matrix in C 1 -C 4 Obtaining a first solution by using the low carbon alcohol;
b. dissolving polybasic acid in C 1 -C 4 To obtain a second solution;
c. dropwise adding the second solution into the first solution under the stirring state to generate a first precipitate;
d. c, separating the first precipitate generated in the step c to obtain a solid substance;
e. dissolving a salt of the metal active component platinum in C 1 -C 4 Obtaining a third solution by using the low-carbon alcohol;
f. redispersing the solid material obtained in step d in C 1 -C 4 To obtain a fourth solution; dropwise adding the third solution into the fourth solution under stirring to generate a second precipitate;
g. separating the second precipitate generated in the step f to obtain the metal-polymer composite catalyst;
wherein, in each preparation step, preferably, in the step a, the mass concentration of the high molecular polymerization monomer in the first solution is 0.01-1 mmol/mL; preferably 0.1 to 0.5mmol/mL.
Preferably, in the step b, the amount concentration of the polybasic acid substance in the second solution is 0.01-1 mmol/mL; preferably 0.1 to 0.5mmol/mL.
Preferably, in the step e, the mass concentration of the salt of the metal active component platinum in the third solution is 0.01-1 mmol/mL; preferably 0.05 to 0.1mmol/mL.
Preferably, in the step f, the mass concentration of the solid matters in the fourth solution is 0.05-0.2 g/mL; preferably 0.1 to 0.2g/mL.
In the present invention, the salt of the metal active ingredient platinum is preferably a soluble salt of the above metal active ingredient platinum, such as a nitrate, a sulfate, a chloride or an acetate.
In the present invention, said C 1 -C 4 The lower alcohols of (a) include, but are not limited to: methanol, ethanol, propanol, n-butanol, preferably methanol and/or ethanol.
In the steps d and g of the above preparation method, the separation can be various separation methods conventional in the art, such as vacuum filtration, and after the separation, a washing step is preferably performed, and in the step g, after the washing, a drying step is preferably further included, and the drying condition is, for example, 60 to 100 ℃ for 6 to 10 hours.
In the present invention, the particles of the raney alloy preferably have an average particle diameter of 0.1 to 1000 μm, preferably 10 to 100 μm; the raney alloy comprises raney metal and leachable elements, wherein "raney metal" refers to a metal that is insoluble when activated by raney, and most typically at least one of nickel, cobalt, copper and iron. "leachable elements" means elements that are soluble when activated by the raney process, and typically are at least one of aluminum, zinc, and silicon. In the present invention, preferably, the weight ratio of the raney metal to leachable elements is 1:99 to 10:1, preferably 1: 10-4: 1. in order to improve the activity or selectivity of the catalyst, the Raney alloy can also be introduced with a promoter, the promoter is selected from at least one of Mo, cr, ti, pt, pd, rh and Ru to form the Raney alloy with multiple components, and the amount of the promoter is 0.01-5% of the total amount of the Raney alloy.
In the present invention, the organic matter that can be carbonized means: treating organic matter at certain temperature and atmosphere condition to volatilize most or all of hydrogen, oxygen, nitrogen, sulfur and other components in the organic matter, so as to obtain one kind of synthetic material with high carbon content. The carbonizable organic substance according to the present invention is preferably at least one of an organic polymer compound, coal, natural asphalt, petroleum asphalt, and coal tar asphalt; more preferably, the organic substance that can be carbonized is an organic polymer compound. The organic high molecular compound comprises a synthetic high molecular compound and/or a natural organic high molecular compound; wherein, the synthetic high molecular compound can be rubber and/or plastic, and the natural organic high molecular compound can be selected from at least one of starch, viscose fiber, lignin and cellulose; the plastic can be thermosetting plastic and/or thermoplastic plastic, the thermoplastic plastic can be at least one selected from polystyrene, styrene-divinylbenzene copolymer and polyacrylonitrile; the rubber is styrene butadiene rubber and/or polyurethane rubber. The organic polymer compound is at least one of epoxy resin, phenolic resin, furan resin, polystyrene, styrene-divinylbenzene copolymer, polyacrylonitrile, starch, viscose fiber, lignin, cellulose, styrene butadiene rubber and polyurethane rubber.
The invention provides a preparation method of the composite hydrogenation catalyst, which comprises the following steps:
a. preparing a curing system according to a common curing formula of a carbonizable organic matter and a mixture thereof, wherein the curing system is in a liquid state or a powder state;
b. b, uniformly mixing the Raney alloy particles with the curing system obtained in the step a, and then carrying out die pressing curing to obtain a catalyst precursor;
c. under the protection of inert gas, carbonizing the obtained catalyst precursor at high temperature to prepare the composite hydrogenation catalyst.
In step a, preparing a curing system according to a common curing formula of the carbonizable organic matter, wherein one or more optional additives selected from the following additives can be added during preparation: cure accelerators, dyes, pigments, colorants, antioxidants, stabilizers, plasticizers, lubricants, flow modifiers or adjuvants, flame retardants, drip retardants, antiblocking agents, adhesion promoters, conductive agents, polyvalent metal ions, impact modifiers, mold release aids, nucleating agents, and the like. The dosage of the used additives is conventional dosage or is adjusted according to the requirements of actual conditions. The prepared curing system is a liquid system or a powder system, and the liquid system can be directly and uniformly stirred; the powdery solid system can be directly and uniformly blended; the granular solid system can be pulverized by any pulverizing equipment commonly used in industry and then uniformly blended.
In step b, the weight ratio of the raney alloy particles to the carbonizable organic curing system is 1:99 to 99:1, preferably 10: 90-90: 10, more preferably 25: 75-75: 25. the obtained catalyst precursor can be processed into particles which can be used in fixed bed or fluidized bed reaction by cutting, stamping or crushing by any available organic polymer material processing equipment, the particle size of the particles is based on the particle size which can meet the requirement of the fixed bed catalyst or fluidized bed catalyst, the shape of the particles can be any irregular shape, spheroid, hemispheroid, cylinder, semicylindrical, prism, cube, cuboid, ring, semicylindrical, hollow cylinder, tooth shape or the combination of the above shapes, and the like, preferably sphere, ring, tooth shape, cylinder or the combination of the above shapes.
The carbonization in step c is generally carried out in a tubular heating furnace, the carbonization operation temperature is generally 400-1900 ℃, preferably 600-950 ℃, the protective gas is inert gas such as nitrogen or argon, and the carbonization is carried out for 1-12 hours. For example, phenolic resin is carbonized at 850 ℃ for 3 hours, and then the phenolic resin is completely carbonized to form porous carbon. The higher carbonization temperature can make the carbon obtained after carbonization more regular.
The catalyst obtained by the invention can be easily activated, and the activation conditions are generally as follows: at 25-95 deg.c, dissolving out at least one of Al, zn and Si with alkali solution in 0.5-30 wt% concentration, and treating with NaOH or KOH for 5 min-72 hr.
The loading of the raney metal in the catalyst can be easily controlled by controlling the addition of the raney alloy and/or controlling the activation degree of the catalyst during the preparation of the catalyst, for example, an activated catalyst with a raney metal loading of 1 to 90wt% (based on 100% of the total weight of the catalyst), preferably an activated catalyst with a raney metal loading of 10 to 80wt%, more preferably 40 to 80wt% can be obtained.
The present invention will be further described with reference to the following examples, but the scope of the present invention is not limited to these examples.
Preparation example 1
3g (0.03 mol) of Polyvinylimidazole (PVIM) were weighed out and dissolved in 200ml of methanol, and 50ml of a 0.1mmol/ml methanol solution of peroxomolybdic acid (homemade, commercially available molybdenum powder dissolved in 30% hydrogen peroxide) were added dropwise with stirring, and a solid material immediately appeared in the solution. After the addition was complete, stirring was maintained for 4h. Finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8 hours to obtain the peroxymolybdic acid-polyvinyl imidazole macromolecule, which is marked as PMo.
2g of PMo was dispersed in 20ml of methanol, and 40ml of a platinum nitrate methanol solution having a platinum concentration of 0.5mg/ml was added dropwise with stirring. After the end of the dropwise addition, stirring was maintained for 4h. And finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8 hours to obtain the platinum-peroxymolybdic acid-polyvinyl imidazole composite catalyst with 1% platinum load, which is numbered CAT-1.
Preparation example 2
3g (0.03 mol) of Polyvinylimidazole (PVIM) are dissolved in 200ml of methanol and 50ml of a 0.1mmol/ml methanol solution of peroxomolybdic acid (self-made, commercially available molybdenum powder dissolved in 30% hydrogen peroxide) are added dropwise with stirring, solid matter immediately appearing in the solution. After the addition was complete, stirring was maintained for 4h. Finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8 hours to obtain the peroxymolybdic acid-polyvinyl imidazole macromolecule, which is marked as PMo.
2g of PMo was dispersed in 20ml of methanol, and 40ml of a methanol solution of platinum nitrate having a platinum concentration of 0.05mg/ml was added dropwise with stirring. After the end of the dropwise addition, stirring was maintained for 4h. Finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8h to obtain the platinum-peroxymolybdic acid-polyvinyl imidazole composite catalyst with the platinum load of 0.1 percent, and the serial number of CAT-2.
Preparation example 3
3g (0.03 mol) of Polyvinylimidazole (PVIM) are dissolved in 200ml of methanol and 50ml of a 0.1mmol/ml methanol solution of peroxomolybdic acid (self-made, commercially available molybdenum powder dissolved in 30% hydrogen peroxide) are added dropwise with stirring, solid matter immediately appearing in the solution. After the addition was complete, stirring was maintained for 4h. Finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8 hours to obtain the peroxymolybdic acid-polyvinyl imidazole polymer, which is marked as PMo.
2g of PMo were dispersed in 20ml of methanol, and 40ml of a platinum nitrate methanol solution having a platinum concentration of 0.25mg/ml was added dropwise with stirring. After the end of the dropwise addition, stirring was maintained for 4h. Finally, after vacuum filtration and methanol washing for 3 times, drying at 80 ℃ for 8h to obtain the platinum-peroxymolybdic acid-polyvinyl imidazole composite catalyst with the platinum load of 0.5 percent, which is numbered CAT-3.
Preparation example 4
(1) Uniformly stirring 100 parts by mass of liquid epoxy resin (Balingpetrochemical, CYD-128), 85 parts by mass of curing agent methyl tetrahydrophthalic anhydride (MeTHPA) (Kyoto Korsa GmbH) and 1.5 parts by mass of curing accelerator Triethanolamine (TEA) (chemical reagent of Tianjin City);
(2) Weighing 40g of the epoxy system prepared in the step (1) and 180g of nickel-aluminum alloy powder, fully stirring and mixing, wherein the Ni content in the nickel-aluminum alloy is 48% (weight) and the aluminum content is 52% (weight), adding a proper amount of the mixture into a cylindrical mold, molding for 30min at the temperature of 120 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, molding for 90min at the temperature of 150 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, cooling and taking out to obtain a granular catalyst precursor;
(3) Measuring 100ml of catalyst precursor, putting the catalyst precursor into a tubular high-temperature electric furnace, keeping the temperature for 3 hours at the heating rate of 10 ℃/min and the carbonization temperature of 600 ℃, and carrying out nitrogen protection with the nitrogen flow of 200ml/min to obtain the composite catalyst after the catalyst precursor is cooled under the nitrogen protection;
(4) Preparing 400g of NaOH aqueous solution 20 percent by using deionized water, adding 50ml of the catalyst obtained in the step (3), keeping the temperature at 85 ℃, filtering the solution after 4 hours to obtain the activated composite catalyst, wherein the nickel metal loading amount in the final catalyst is about 60 percent (weight), washing to be nearly neutral, and storing in the deionized water for later use, and the catalyst is marked as CAT-4.
Preparation example 5
(1) Uniformly stirring 100 parts by mass of liquid epoxy resin (ba ling petrochemical, CYD-128), 85 parts by mass of curing agent methyl tetrahydrophthalic anhydride (MeTHPA) (Kyoto Kodao Co., ltd., guangdong Shengshida) and 1.5 parts by mass of curing accelerator Triethanolamine (TEA) (chemical reagent factory, tianjin city);
(2) Weighing 50g of the epoxy system prepared in the step (1) and 150g of nickel-aluminum alloy powder, fully stirring and mixing, wherein the Ni content in the nickel-aluminum alloy is 48% (weight) and the aluminum content is 52% (weight), adding a proper amount of mixture into a cylindrical mold, molding for 30min at the temperature of 120 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, molding for 90min at the temperature of 150 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, cooling and taking out to obtain a granular catalyst precursor;
(3) Measuring 100ml of catalyst precursor, putting the catalyst precursor into a tubular high-temperature electric furnace, keeping the temperature for 3 hours at the heating rate of 10 ℃/min and the carbonization temperature of 700 ℃, and carrying out nitrogen protection with the nitrogen flow of 200ml/min to obtain the composite catalyst after the catalyst precursor is cooled;
(4) Preparing 400g of NaOH aqueous solution 20 percent by using deionized water, adding 50ml of the catalyst obtained in the step (3), keeping the temperature at 85 ℃, filtering the solution after 4 hours to obtain the activated composite catalyst, wherein the nickel metal loading amount in the final catalyst is about 50 percent (weight), washing to be nearly neutral, and storing in the deionized water for later use, and the catalyst is marked as CAT-5.
Preparation example 6
(1) Uniformly stirring 100 parts by mass of liquid epoxy resin (ba ling petrochemical, CYD-128), 85 parts by mass of curing agent methyl tetrahydrophthalic anhydride (MeTHPA) (Kyoto Kodao Co., ltd., guangdong Shengshida) and 1.5 parts by mass of curing accelerator Triethanolamine (TEA) (chemical reagent factory, tianjin city);
(2) Weighing 50g of the epoxy system prepared in the step (1) and 130g of nickel-aluminum alloy powder, fully stirring and mixing, wherein the Ni content in the nickel-aluminum alloy is 48% (weight) and the aluminum content is 52% (weight), adding a proper amount of mixture into a cylindrical mold, molding for 30min at the temperature of 120 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, molding for 90min at the temperature of 150 ℃ and the pressure of 7MPa by using a flat-plate vulcanizing instrument, cooling and taking out to obtain a granular catalyst precursor;
(3) Measuring 100ml of catalyst precursor, putting the catalyst precursor into a tubular high-temperature electric furnace, keeping the temperature at the rate of 10 ℃/min and the carbonization temperature at 800 ℃ for 3 hours under the protection of nitrogen, wherein the nitrogen flow is 200ml/min, and cooling under the protection of nitrogen to obtain the composite catalyst;
(4) Preparing 400g of NaOH aqueous solution 20 percent by using deionized water, adding 50ml of the catalyst obtained in the step (3), keeping the temperature at 85 ℃, filtering the solution after 4 hours to obtain the activated composite catalyst, wherein the nickel metal loading amount in the final catalyst is about 45 percent (weight), washing to be nearly neutral, and storing in the deionized water for later use, and the catalyst is marked as CAT-6.
Test example 1
5mL of catalyst (a first reactor adopts a slurry bed operation mode, and is filled with the catalyst CAT-1 of the preparation example 1, a second reactor adopts a fixed bed operation mode, and is filled with the catalyst CAT-4 of the preparation example 4, the two reactors are connected in series) is filled into a stainless steel reactor with the inner diameter of 14mm, the reaction gas is industrial-grade hydrogen, the hydrogen flow is 300mL/min, the reaction liquid raw material is a mixture of benzene and the product cyclohexane, wherein the benzene content is 50% (by weight), the sample is injected by a micro-pump, the liquid flow is 0.5mL/min, the temperature of the first reactor is 100 ℃, the temperature of the second reactor is 180 ℃, and the reaction pressure is 4.0MPa. The reaction product was analyzed by Agilent 7890A gas chromatography, and the FID detector and the benzene hydrogenation reaction results are shown in Table 1.
Test example 2
The difference from test example 1 is that: the first stage reactor was charged with CAT-2 catalyst from preparation 2.
Test example 3
The difference from test example 1 is that: the first stage reactor was charged with CAT-3, catalyst preparation 3.
Test example 4
The difference from test example 1 is that: the second stage reactor was charged with CAT-5 catalyst from preparation 5.
Test example 5
The difference from test example 1 is that: the second stage reactor was charged with CAT-6 catalyst of preparation 6.
Comparative example 1
The differences from test example 1 are: only the first stage reactor was used.
Comparative example 2
The difference from test example 1 is: only the second stage reactor was used.
TABLE 1
As can be seen from the above table, the metal-polymer catalyst and the composite hydrogenation catalyst are used for hydrogenation in sequence, and benzene is completely hydrogenated to generate cyclohexane through two-stage hydrogenation.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.
Claims (21)
1. The method for preparing cyclohexane by benzene hydrogenation is characterized by being carried out in two reactors connected in series, wherein a first reactor is filled with a metal-polymer composite catalyst, and a second reactor is filled with a composite hydrogenation catalyst;
the metal-polymer composite catalyst comprises a polyacid crosslinked polymer matrix and a metal active component platinum, wherein the polymer matrix is a polymer containing a nitrogen-containing heterocyclic side group, nitrogen atoms in the nitrogen-containing heterocyclic side group have lone-pair electrons, and at least part of the metal active component platinum and the lone-pair electrons of the nitrogen atoms form coordination bonds;
the composite hydrogenation catalyst comprises continuous phase carbon and dispersed phase Raney alloy particles, wherein the dispersed phase Raney alloy particles are uniformly or non-uniformly dispersed in the continuous phase carbon, and the continuous phase carbon is obtained by carbonizing a carbonizable organic matter or a mixture thereof;
the first-stage reactor is a slurry bed reactor, the reaction temperature of the first-stage reactor is 80 to 100 ℃, and the reaction pressure is 1.0 to 5MPa; the liquid phase volume space velocity is 0.1 to 10h -1 ；
The second-stage reactor is a fixed bed reactor, the reaction temperature of the second-stage reactor is 100 to 180 ℃, and the reaction pressure is 1.0 to 5MPa; the liquid phase airspeed is 0.1 to 20h -1 。
2. The method for preparing cyclohexane by hydrogenation of benzene as claimed in claim 1, wherein the space velocity of the liquid phase volume of the first-stage reactor is 0.5 to 5h -1 (ii) a The feeding molar ratio of the raw material benzene to the hydrogen is 1:3 to 10;
the liquid phase airspeed of the second-stage reactor is 5 to 10h -1 。
3. The process for the hydrogenation of benzene to produce cyclohexane according to claim 1, wherein,
the polyacid crosslinked polymer matrix is obtained by the coordination crosslinking action of the polymer matrix on polyacid; the polybasic acid is an inorganic acid and/or an organic acid capable of dissociating two or more hydrogen ions;
the nitrogen-containing heterocyclic side group is imidazolyl and/or pyridyl;
the content of a metal active component platinum in the metal-polymer composite catalyst is 0.1 to 5wt%.
4. The process for the hydrogenation of benzene to produce cyclohexane according to claim 3, wherein,
the polybasic acid is at least one of sulfuric acid, phosphoric acid, citric acid, peroxymolybdic acid and chloroplatinic acid;
the polymeric monomer of the polymer matrix comprises C containing imidazolyl and/or pyridyl 2 -C 6 An olefin.
5. The method for preparing cyclohexane by hydrogenating benzene according to claim 1, wherein the molar ratio of the polybasic acid to the nitrogen-containing heterocyclic side group contained in the polymer matrix is 1 (4 to 50); the molar ratio of the metal active component platinum to the nitrogen-containing heterocyclic ring side group contained in the polymer matrix is 1 (6 to 1500).
6. The process for the hydrogenation of benzene to cyclohexane according to claim 5, wherein,
the molar ratio of the polybasic acid to the nitrogen-containing heterocyclic ring side group contained in the polymer matrix is 1 (4 to 20);
the molar ratio of the metal active component platinum to the nitrogen-containing heterocyclic ring side group contained in the polymer matrix is 1 (6 to 1000).
7. The method for preparing cyclohexane by hydrogenation of benzene according to claim 1, wherein the method for preparing the metal-polymer composite catalyst comprises:
a. dissolving or dispersing the polymer matrix in C 1 -C 4 Obtaining a first solution by using the low-carbon alcohol;
b. dissolving polybasic acid in C 1 -C 4 To obtain a second solution;
c. dropwise adding the second solution into the first solution under the stirring state to generate a first precipitate;
d. c, separating the first precipitate generated in the step c to obtain a solid substance;
e. dissolving a salt of the metal active component platinum in C 1 -C 4 Obtaining a third solution by using the low-carbon alcohol;
f. redispersing the solid material obtained in step d in C 1 -C 4 To obtain a fourth solution; dropwise adding the third solution into the fourth solution under stirring to generate a second precipitate;
g. and f, separating the second precipitate generated in the step f to obtain the metal-polymer composite catalyst.
8. The process for the hydrogenation of benzene to produce cyclohexane according to claim 7, wherein,
in the step a, the mass concentration of the high molecular polymer monomer in the first solution is 0.01 to 1mmol/mL;
in the step b, the mass concentration of the polybasic acid substance in the second solution is 0.01 to 1mmol/mL;
in the step e, the mass concentration of the metal active component platinum salt in the third solution is 0.01 to 1mmol/mL;
in the step f, the mass concentration of the solid matters in the fourth solution is 0.05-0.2g/mL.
9. The process for the hydrogenation of benzene to produce cyclohexane as claimed in claim 8, wherein,
in the step a, the mass concentration of the high molecular polymerization monomer in the first solution is 0.1 to 0.5mmol/mL;
in the step b, the mass concentration of the polybasic acid in the second solution is 0.1 to 0.5mmol/mL;
in the step e, the mass concentration of the metal active component platinum salt in the third solution is 0.05 to 0.1mmol/mL;
in the step f, the mass concentration of the solid matter in the fourth solution is 0.1-0.2g/mL.
10. The method for producing cyclohexane by hydrogenation of benzene according to claim 1, wherein the particles of the raney alloy have an average particle diameter of 0.1 to 1000 μm;
the raney alloy comprising raney metal and a leachable element; the weight ratio of the raney metal to leachable elements is 1:99 to 10:1.
11. the process for the hydrogenation of benzene to produce cyclohexane according to claim 10, wherein,
the average particle diameter of the Raney alloy particles is 10 to 100 mu m;
the raney metal is at least one of nickel, cobalt, copper and iron, and the leachable element is selected from at least one of aluminum, zinc and silicon;
the weight ratio of the raney metal to leachable elements is 1:10 to 4:1.
12. the method for preparing cyclohexane by benzene hydrogenation according to claim 10, wherein the Raney alloy further comprises at least one promoter selected from Mo, cr, ti, pt, pd, rh and Ru, and the promoter accounts for 0.01 to 5 percent of the total weight of the Raney alloy.
13. The method for preparing cyclohexane by hydrogenation of benzene according to claim 1, wherein the carbonizable organic substance is at least one of an organic polymer compound, coal, natural asphalt, petroleum asphalt, and coal tar asphalt;
the organic polymer compound is a synthetic polymer compound and/or a natural organic polymer compound.
14. The process for the hydrogenation of benzene to cyclohexane according to claim 13, wherein,
the organic matter capable of being carbonized is an organic high molecular compound;
the natural organic high molecular compound is starch and/or cellulose lignin; the synthetic polymer compound is rubber and/or plastic.
15. The process for the hydrogenation of benzene to produce cyclohexane as claimed in claim 14, wherein,
the plastic is a thermosetting plastic and/or a thermoplastic plastic.
16. The method for preparing cyclohexane by hydrogenation of benzene according to claim 13, wherein the organic polymer compound is at least one of epoxy resin, phenol resin, furan resin, polystyrene, styrene-divinylbenzene copolymer, polyacrylonitrile, starch, viscose, lignin, cellulose, styrene-butadiene rubber and urethane rubber.
17. The method for preparing cyclohexane by hydrogenation of benzene as claimed in claim 1, wherein the preparing step of the composite hydrogenation catalyst comprises:
a. preparing a curing system according to a common curing formula of a carbonizable organic matter and a mixture thereof, wherein the curing system is in a liquid state or a powder state;
b. b, uniformly mixing the Raney alloy particles with the curing system obtained in the step a, and then carrying out die pressing curing to obtain a catalyst precursor;
c. under the protection of inert gas, carbonizing the obtained catalyst precursor at high temperature to prepare the composite hydrogenation catalyst.
18. The method for preparing cyclohexane by benzene hydrogenation according to claim 17, wherein the weight ratio of the raney alloy particles to the carbonizable organic substance curing system is 1:99 to 99:1;
the carbonization is carried out in a tubular heating furnace, and the operation temperature of the carbonization is 400-1900 ℃; the protective gas is inert gas, and the carbonization time is 1 to 12h.
19. The method for preparing cyclohexane by benzene hydrogenation according to claim 18, wherein the weight ratio of the raney alloy particles to the carbonizable organic substance curing system is 10:90 to 90:10;
the operating temperature of carbonization is 600 to 950 ℃.
20. The method for preparing cyclohexane by benzene hydrogenation according to claim 19, wherein the weight ratio of the raney alloy particles to the carbonizable organic substance curing system is 25:75 to 75:25.
21. the method for preparing cyclohexane by hydrogenating benzene as claimed in claim 17, wherein the activating method of the composite hydrogenation catalyst comprises: and (3) activating the composite hydrogenation catalyst by using an alkali solution with the concentration of 0.5-30wt% for 5 min-72h at the temperature of 25-95 ℃.
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