CN110575759B - Single-walled carbon nanotube-metal hybrid AlPO 4 Preparation method of-5 molecular sieve composite membrane - Google Patents
Single-walled carbon nanotube-metal hybrid AlPO 4 Preparation method of-5 molecular sieve composite membrane Download PDFInfo
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Abstract
The invention discloses a single-walled carbon nanotube-metal hybrid AlPO 4 -5 molecular sieve composite membrane preparation method by using positive polarity streamer discharge technology in AlPO 4 -5 preparing single-walled carbon nanotubes (SWCNTs) in the pore canal of the molecular sieve membrane, greatly reducing the time, reaction temperature and energy consumption of the preparation process, and effectively improving the content of the single-walled carbon nanotubes (SWCNTs) in the pore canal of the membrane, the completeness of the composite molecular sieve membrane and the membrane forming efficiency.
Description
The technical field is as follows:
the invention relates to the technical field of inorganic membrane materials and membrane separation, in particular to single-walled carbon nanotube-metal hybrid AlPO 4 -5 preparation method of molecular sieve composite membrane.
The background art comprises the following steps:
the molecular sieve membrane can realize molecular sieving or shape-selective diffusion according to the size, shape and polarity of the molecules of the separated substances by means of a regular pore channel structure of the molecular sieve, thereby realizing high-efficiency separation of gas phase or liquid phase mixtures. If other catalytic active components are introduced into the molecular sieve membrane to prepare the zeolite molecular sieve membrane reactor, the reaction process and the separation process can be conveniently coupled together, so that the molecular sieve membrane reactor has dual functions of separation and catalysis at the molecular level, reaction and separation integration is realized, the reaction conversion rate is improved, and the reaction and separation process is enhanced. In addition, the molecular sieve membrane can also be used as a matrix of a nano material to carry out the assembly of atomic clusters and supramolecular compounds, thereby obtaining new optical, electrochemical and optoelectronic materials, and having potential application prospects in the fields of photoelectron and electrochemistry. Since the 90 s in the 20 th century, the research of molecular sieve membranes has become one of the hot spots in the research of new catalytic materials and new processes, and the molecular sieve membranes have wide application prospects in various aspects such as gas separation, catalytic membrane reactors, chemical sensors, molecular sieve modified electrodes and the like.
In the current research work, people are continuously researching methods for increasing the selectivity and the permeation flux of the molecular sieve membrane, so that the method can replace the existing gas separation method in the industry, thereby greatly saving manpower, material resources and energy sources, and playing a positive promoting role in the aspect of environmental protection. The functional combination of molecular sieve membrane and other materials is one of the hot points of research, for example, qingling (Chemcomm, 2006, 1230-1232) combines ZSM-5 molecular sieve and carbon membrane and applies them to O 2/ N 2 Separate and obtain a remarkable separation effect, alPO 4 -5 also have related reports (Applied Physics Letters, 2004, 84. AlPO as adsorbent 4 -5 molecular sieve membranes separating mixtures according to molecular size and polarity, and AlPO 4 The performance of-5 molecular sieve membranes is strongly related to their structure (Chemistry Letter,2002,10: 1012-1213). In order to expand AlPO 4 -5 application properties of molecular sieve membranes to AlPO alone 4 The functional composition of the-5 molecular sieve is a hot spot of research at present. Reports have shown that SAPO's are utilized 4 -5 preparing single-walled carbon nanotubes (SWCNTs) by using an organic carbon source in molecular sieve pore channels, and mixing the SWCNTs with the SAPO 4 The characteristics and advantages of the-5 molecular sieve are organically combined into a whole, a hydrocracking method is adopted in the preparation process, but the heating process of the process adopts a traditional heating mode, so that the time consumption is long, the energy consumption is high, and the SWCNTs content in the prepared sample is relatively low.
The invention content is as follows:
the invention aims to provide single-walled carbon nanotube-metal hybrid AlPO 4 -5 molecular sieve composite membrane preparation method by using positive polarity streamer discharge technology in AlPO 4 -5 preparing single-walled carbon nanotubes (SWCNTs) in the pore canal of the molecular sieve membrane, greatly reducing the time, reaction temperature and energy consumption of the preparation process, and effectively improving the content of the single-walled carbon nanotubes (SWCNTs) in the pore canal of the membrane, the completeness of the composite molecular sieve membrane and the membrane forming efficiency.
The invention is realized by the following technical scheme:
single-walled carbon nanotube-metal hybrid AlPO 4 -5 a method for preparing a molecular sieve composite membrane, characterized in that the method comprises the steps of:
1) Preparation of a synthetic solution:
taking an aluminum source, a phosphorus source, an organic template agent and deionized water as raw materials, wherein the molar composition of the raw materials of a reaction system is as follows by oxide: 1Al 2 O 3 :aP 2 O 5 bTemplate (organic template) cH 2 dX, a = 0.8-1.3, b = 0.15-1, c = 45-1000, d = 0.075-0.3, X is transition metal salt; the phosphorus source is phosphoric acid with the mass percentage concentration of 85 percent;
according to the above dosage, under the stirring condition, gradually adding the weighed transition metal salt and aluminum source into the phosphoric acid aqueous solution (the mass percentage concentration is 85% phosphoric acid and deionized water mixed solution), and continuously stirring until the transition metal salt and the aluminum source are completely dissolved; then under the stirring state, dripping the organic template agent into the mixed solution, uniformly stirring, and finally adjusting the pH of the reaction solution to 2.0-6.5 to obtain a synthetic solution;
2) Preparation of metal hybrid AlPO on ceramic carrier surface 4 -5 molecular sieve membrane
Taking a sheet-shaped porous ceramic material with the surface modified by PVA as a carrier, putting a synthetic liquid and the carrier into a tetrafluoro hydrothermal synthesis reaction kettle, ensuring that the synthetic liquid submerges the surface of the carrier, putting the sealed reaction kettle into a drying oven heated to 160-200 ℃, reacting for 24-100 hours at the temperature, naturally cooling the reaction kettle to room temperature after the reaction is finished, taking out a sample, washing the sample to be neutral by using distilled water, drying the sample overnight by using the drying oven 333K, detecting the completeness of the synthesized molecular sieve membrane, and carrying out secondary synthesis on unqualified products until the products are qualified;
3) Single-walled carbon nanotube-metal hybrid AlPO 4 -5 preparation of molecular sieve membrane
Adopting positive polarity streamer discharge technology to hybridize the metal prepared in the step 2) with AlPO 4 -5 molecular sieve membrane is placed in self-made positive polarity streamer discharge electric field, and the sheet membrane body is ensured to be placed perpendicular to the electric field direction, and H is introduced under the condition of 250-500 DEG C 2 O/N 2 、H 2 O/He、H 2 /N 2 Or H 2 Mixed atmosphere of/He, N 2 Or He and H 2 O or H 2 The volume ratio of (A) is 0-10, the flow rate of the mixed gas is 1-100ml/min, the mixed atmosphere is excited to generate high-energy H free radicals under the conditions of 1-60kV pulse voltage, 10-0.1us pulse width and 5-50 pulses per second pulse frequency, and metal hybridization AlPO is utilized 4 -5 self-catalytic performance of the molecular sieve membrane, treating for 12-48 hours without using an additional catalyst, preparing the organic template agent in the pore canal of the molecular sieve membrane into a single-walled carbon nanotube, and finally preparing the single-walled carbon nanotube-metal hybrid AlPO 4 -5 composite molecular sieve membrane.
The aluminum source is aluminum isopropoxide, aluminum sulfate, pseudoboehmite or aluminate, the organic template is selected from tetrapropylammonium hydroxide (TPAOH), tetrapropylammonium bromide (TPABr) or Triethylamine (TEA), and the transition metal X is selected from Fe, co and Ni transition metal salt.
In the step 2), the PVA modified and modified sheet-shaped porous ceramic material is obtained by uniformly coating a layer of structure directing agent PVA on the surface of the sheet-shaped porous ceramic material to increase the adsorption active sites such as hydroxyl on the surface of the carrier, so that a layer of dense cross-linked metal hybrid AlPO grows on the surface of the carrier 4 -5 molecular sieve membranes.
In step 3), the temperature is preferably from 250 to 350 ℃.
The positive polarity streamer discharge technology belongs to one kind of non-heat balance plasma technology, and the streamer head with positive ion cluster as electron collapse head develops to negative pole during discharge and their tracks form one positive and negative ion mixed streamAnd (3) a light channel. In the development process of streamer, a strong power plant on the surface of the streamer head initiates electron avalanche, the energy of the excited high-energy electrons can reach 10-12eV, and the high-energy electrons are the root of the chemical effect of gas corona discharge and are enough to excite H 2 O or H 2 The gas is ionized to generate free radicals such as O, OH, H and the like. The free radicals have higher energy sources, reduce the reaction activation energy required by the cracking reaction of templates such as TPAOH, TEA and the like, and break the template into small molecular compounds such as propane, ethylene and the like, and can form carbon materials with specific structures through further dehydrogenation and polymerization.
The invention adopts positive polarity streamer discharge technology, and excites and fills H in mixed atmosphere within the range of 1-60kV pulse voltage with the pulse width of 10-0.1us and the pulse frequency of 5-50 pulses per second 2 O or H 2 And ionizing to generate O, OH, H and other high-energy free radicals, attacking the C-C bond in the organic template agent by using the high-energy free radicals to break the C-C bond at a lower temperature, and further efficiently preparing the single-walled carbon nanotube at the lower temperature.
Meanwhile, in the reaction process of preparing the single-walled carbon nanotube by using the organic template in the positive-polarity streamer-induced electric field, the transition metal elements on the molecular sieve framework can be used as catalysts to promote the reaction to carry out high-efficiency conversion reaction at a lower temperature, and meanwhile, the adsorption force of the inner wall of the molecular sieve pore channel on an organic carbon source can be increased, the quantity of the organic carbon source escaping out of the molecular sieve pore channel in the reaction process is reduced, and further, the filling proportion of the single-walled carbon nanotube in the molecular sieve membrane pore channel is greatly improved. Finally, the metal is hybridized with AlPO 4 -5 molecular sieve membrane and single-walled carbon nanotube membrane are organically combined into a whole.
The invention can prepare compact single-walled carbon nanotube-metal hybrid AlPO on a macroporous ceramic carrier 4 -5 molecular sieve membrane with high repeatability. And finally, directly preparing the complete non-oriented single-walled carbon nanotube-metal hybrid AlPO on the macroporous carrier by adjusting the composition of the synthetic liquid, the hydrothermal synthesis temperature, coating the structure guiding agent-PVA thickness on the carrier and other synthesis conditions 4 -5 molecular sieve membranes.
The synthesized single-walled carbon nanotube-metal hybrid AlPO of the invention 4 -5 composite filmSingle-walled carbon nanotube membrane and metal hybrid AlPO 4 -5 the advantages of molecular sieve membranes are organically combined together and avoid each other's drawbacks during application; simultaneously, exciting H in filling atmosphere by positive polarity streamer discharge technology 2 O or H 2 The high-energy free radicals such as O, OH, H and the like generated by ionization can effectively reduce the activation energy required by the reaction, thereby avoiding the defect caused by the thermodynamic deformation of the molecular sieve membrane due to high temperature. The low-temperature operation of the process can also effectively reduce the escape amount of the organic template in the preparation process, and improve the filling amount of the single-walled carbon nanotubes in the molecular sieve membrane, thereby obviously improving the gas separation performance and the permeation flux of the composite membrane, which is also one of the main innovation points of the invention.
The carbon nano tube-metal hybrid AlPO prepared by the invention 4 -5 the molecular sieve composite membrane has the following characteristics: (1) The filling concentration of the single-walled carbon nanotube in the composite molecular sieve membrane can be adjusted and increased by changing the synthesis conditions such as material formula and the like; (2) The positive flow corona technology can greatly reduce the generation temperature required by the reaction, and simultaneously can reduce the escape amount of the organic carbon source in the molecular sieve membrane in the preparation process, thereby increasing the completeness of the composite membrane; (3) Prepared composite membrane pair CH 4 /CO 2 The mixed gas shows higher selectivity and permeation flux. The method has the advantages of mild process conditions, simpler operation, lower cost, higher film forming efficiency and wider applicability.
In summary, the present invention utilizes the positive polarity streamer discharge technique at lower temperatures at AlPO 4 -5, efficiently preparing non-oriented single-walled carbon nanotubes (SWCNTs) in the pore canal of the molecular sieve membrane, effectively avoiding the formation of intercrystalline defects in the molecular sieve membrane, and enabling the cracked organic template to form the single-walled carbon nanotubes in the pore canal of the molecular sieve membrane, thereby greatly reducing the time, reaction temperature and energy consumption of the preparation process, effectively improving the content of the single-walled carbon nanotubes (SWCNTs) in the pore canal of the membrane, the completeness and the membrane forming efficiency of the composite molecular sieve membrane, and enabling the prepared composite membrane to be used for CH coating 4 /CO 2 The mixed gas shows higher selectivity and permeation flux.
Description of the drawings:
FIG. 1 is a Raman spectrum of the molecular sieve composite membrane obtained in examples 1 to 4 of the present invention,
wherein, (1) - (4) are Raman spectrograms of the molecular sieve composite membrane in samples 1-4 respectively, and RBM is a Raman characteristic peak of the single-walled carbon nanotube;
FIG. 2 is NiAlPO in example 1 of the present invention 4 -5 fluorescence microscope photograph and transmission electron microscope photograph of molecular sieve on the surface of the molecular sieve composite membrane;
FIG. 3 is CoAlPO in example 2 of the present invention 4 -5 SEM and fluorescence microscopy of the front side of the molecular sieve composite membrane;
FIG. 4 shows FeAlPO in example 3 of the present invention 4 -5 SEM and fluorescence microscope photographs of the cross section of the molecular sieve composite membrane;
FIG. 5 shows FeAlPO in example 4 of the present invention 4 -5 SEM and fluorescence microscope pictures of the cross section of the molecular sieve composite membrane.
The specific implementation mode is as follows:
the following is a further description of the invention and is not intended to be limiting.
Example 1:
(1) Preparation of FeAlPO on porous ceramic support 4 -5 molecular sieve membrane
According to 1Al 2 O 3 :1.3P 2 O 5 :1TPABr:1000H 2 O:0.3FeCl 3 (mol) preparing synthetic liquid. Aluminum isopropoxide is used as an aluminum source, in order to be fully dissolved, the aluminum isopropoxide is added into a phosphoric acid aqueous solution, the mixture is stirred and dissolved for about 5 hours in an oil bath at the temperature of 60 ℃, and the dissolved aluminum isopropoxide aqueous solution is basically transparent liquid. Then FeCl is added under stirring 3 Adding the mixture into phosphoric acid water solution dissolved with aluminum isopropoxide, and continuing stirring until the mixture is completely dissolved. TPABr was added dropwise to the mixed solution with stirring, and stirred for two hours to dissolve the substances completely, and the pH of the resultant solution was adjusted to 6, followed by aging at room temperature for 10 hours. Placing 20ml of synthetic liquid and a sheet-shaped porous ceramic carrier with the surface modified by PVA in a tetrafluoro crystallization kettle, ensuring that the carrier is completely immersed in the synthetic liquid, then placing the reaction kettle in a drying oven which is heated to 160 ℃, and carrying out reverse reactionThis should be done for 100 hours. After the reaction is finished, the reaction kettle is naturally cooled to the room temperature, and then a sample is taken out, washed to be neutral by distilled water and dried overnight in an oven 333K.
(2)FeAlPO 4 -5 detection of molecular sieve membrane integrity
The invention adopts a gas leakage detection method to detect the completeness of the prepared molecular sieve membrane. The complete molecular sieve membrane without the template agent is not breathable, and if gas permeates through the molecular sieve membrane body, the prepared molecular sieve membrane has defects. Therefore, in the present invention, N is used at the intake end 2 Using gas as tracer gas, using He as purge gas at permeation end, and measuring N at permeation end 2 The completeness of the molecular sieve membrane can be judged according to the gas content. In a leakage test, the membrane pool is kept at 25 ℃, the pressure of the air inlet end is set to be 0.5MPa, the permeation gas is directly blown by the normal pressure He with the gas velocity of 10ml/min to enter the gas chromatography, and the N in the gas chromatography is measured on line 2 Gas content. When N is present 2 Gas permeation amount less than 5 × 10 －11 mol·m －2 ·Pa －1 When the molecular sieve membrane is prepared, the prepared molecular sieve membrane is considered to be complete. Synthesized FeAlPO 4 -5 molecular sieve membrane N 2 Gas permeation amount is less than 5 × 10 －11 mol·m －2 ·Pa －1 The synthesized molecular sieve membrane is indicated to be complete FeAlPO 4 -5 molecular sieve membranes.
(3) Single-walled carbon nanotube-FeAlPO 4 -5 preparation of molecular sieve composite membrane
The prepared FeAlPO 4 -5 molecular sieve membrane is placed in a self-made positive polarity streamer discharge electric field, and the sheet-shaped membrane body is ensured to be placed perpendicular to the direction of the electric field, the temperature in the electric field is maintained at 250 ℃, the pulse voltage is 1kV, and H with the pulse width of 10us and the pulse frequency of 50 pulses per second and the excitation volume ratio of 10 is adopted 2 O/N 2 The flow rate of the mixed gas is 1ml/min. Under the condition, feAlPO is treated 4 Naturally cooling to room temperature after-5 molecular sieve membrane is used for 12 hours, and taking out the prepared single-walled carbon nanotube-FeAlPO 4 -5 molecular sieve composite membrane. The Raman spectrum is shown in FIG. 1, and the fluorescence microscope photograph and the transmission electron microscope photograph are shown in FIG. 2.
Example 2
(1)NiAlPO 4 -5 preparation of molecular sieve membrane
Essentially the same as example 1, except that aluminum sulfate was used as the aluminum source, as 1Al 2 O 3 :0.8P 2 O 5 :0.15TPAOH: 45H 2 O:0.075Ni(NO 3 ) 2 (mol) preparing synthetic liquid according to the material proportion. The fully dissolved aluminum sulfate aqueous solution is basically transparent liquid. Then, a certain amount of phosphoric acid solution dissolved with nickel nitrate is dripped into the aluminum sulfate aqueous solution and is stirred at room temperature until the mixture is uniform. Under the condition of stirring, TPAOH is gradually and sequentially added into the mixed solution in a dropwise manner, the stirring is continued for 2 hours, and after all the substances are completely dissolved, the Ph of the reaction solution is adjusted to be about 2. The reaction solution was aged at room temperature for 20 hours before being charged into the reaction vessel. Then, 30ml of synthetic solution and a sheet-shaped porous ceramic carrier with the surface modified by PVA are placed in a tetrafluoro crystallization kettle, and the carrier is placed perpendicular to the liquid level of the reaction solution. The reaction vessel was placed in an oven which had been warmed to 200 ℃ and the reaction was carried out for 24 hours. After the reaction is finished, the reaction kettle is naturally cooled to room temperature, and then a sample is taken out, washed by distilled water and dried overnight in an oven 333K.
(2)NiAlPO 4 -5 detection of molecular sieve membrane integrity
The concrete operation steps are the same as those in example 1
The NiAlPO-5 molecular sieve membrane obtained after two times of synthesis reaction, and N thereof 2 The gas permeation amount is generally less than 5 x 10 －11 mol·m －2 ·Pa －1 The synthesized NiAlPO-5 molecular sieve membrane has no intercrystalline defects.
(3) Preparation of single-walled carbon nanotube-NiAlPO-5 molecular sieve composite membrane
Substantially the same as in example 1, except that the temperature in the electric field was maintained at 350 ℃ and the pulse voltage was 1kV, water vapor was excited at a pulse width of 10us and a pulse frequency of 50 pulses per second, and the gas flow rate was 100ml/min. Under the condition, the NiAlPO-5 molecular sieve membrane is treated for 48 hours, then naturally cooled to room temperature, and the prepared single-walled carbon nanotube-NiAlPO-5 molecular sieve composite membrane is taken out. The Raman spectrum is shown in FIG. 1, and the front SEM and fluorescence micrograph is shown in FIG. 3.
Example 3
(1) Preparation of CoAlPO-5 molecular sieve membrane on porous alumina support
Essentially the same as in example 1, except that sodium aluminate was used as the aluminum source, in accordance with 1Al 2 O 3 :1.3P 2 O 5 :0.5TPABr: 200H 2 O:0.15Co(NO 3 ) 3 (mol) preparing synthetic liquid. The reaction temperature was 180 ℃ and the reaction time was 100 hours.
(2) Detection of completeness of CoAlPO-5 molecular sieve membrane
The concrete operation steps are the same as those in example 1
The CoAlPO-5 molecular sieve membrane obtained after two times of synthesis reactions, and N thereof 2 The gas permeation amount is generally less than 5 x 10 －11 mol·m －2 ·Pa －1 (ii) a The synthesized tubular CoAlPO-5 molecular sieve membrane has almost no intercrystalline defects.
(3) Preparation of single-walled carbon nanotube-CoAlPO-5 molecular sieve composite membrane
Essentially the same as in example 1, except that the temperature in the electric field was maintained at 500 ℃ and the pulse voltage was 60kV, H was excited at a pulse width of 0.1us and a pulse frequency of 5 pulses per second in a volume ratio of 10 2 The flow rate of the mixed gas is 50ml/min. Under the condition, the CoAlPO-5 molecular sieve membrane is treated for 24 hours, then naturally cooled to room temperature, and the prepared single-walled carbon nanotube-CoAlPO-5 molecular sieve composite membrane is taken out. The Raman spectrum is shown in FIG. 1, and the SEM and fluorescence micrograph of the cross section is shown in FIG. 4.
Example 4
(1) Preparation of FeAlPO on porous ceramic support 4 -5 molecular sieve membrane
The method is substantially the same as in example 1, except that pseudo-boehmite is used as an aluminum source and triethylamine is used as a template. The reaction temperature was 180 ℃ and the reaction time was 100 hours.
(2) Preparation of specially oriented FeAlPO 4 -5 detection of molecular sieve membrane integrity
The concrete operation steps are the same as those in example 1
For the synthesized FeAlPO of specific orientation 4 -5 molecular sieve membrane, N thereof 2 The gas permeation amount is less than 5 × 10 － 11 mol·m －2 ·Pa －1 (ii) a The synthesized molecular sieve membrane is complete FeAlPO 4 -5 molecular sieve membranes.
(3) Single-walled carbon nanotube-FeAlPO 4 -5 preparation of molecular sieve composite membrane
Essentially the same as in example 1, except that the temperature in the electric field was maintained at 500 ℃ and the pulse voltage was 30kV, H was excited at a pulse width of 1us and a pulse frequency of 25 pulses per second 2 The gas flow rate is 30ml/min. Under the condition, feAlPO is treated 4 After 24 hours, naturally cooling to room temperature, and taking out the prepared single-walled carbon nanotube-FeAlPO 4 -5 molecular sieve composite membrane. The Raman spectrum is shown in FIG. 1. The SEM and fluorescence micrograph of the cross section is shown in FIG. 5.
Example 5:
gas membrane separation experiment
A self-made membrane separation device is adopted. First, the molecular sieve membranes obtained in examples 1 to 4 were fixed in a home-made membrane cell using a Teflon washer, and the effective area of the membrane was about 2.0cm 2 (ii) a Then, the gas inlet end of the membrane pool is connected to the gas outlet end of the gas mixing tank, and the gas outlet of the membrane pool is connected to the gas chromatograph, so that the on-line detection and analysis of the separated gas are realized. In the experiment, the gas separation performance of the synthesized composite membrane was measured by measuring the flux of the permeate gas and the separation factor.
Pervaporation performance of different molecular sieve membranes
In the gas permeation separation experiment, the pressure drop is 0.02Mpa, the temperature is 25 ℃, and the ratio of the gas flow velocity before passing through the membrane is VCO 2 /VCH 4 =1, detection of CO after passage through membrane by gas chromatography 2 And CH 4 Flow velocity V of CO2 And V CH4 Calculating selection factor and permeability, wherein CO 2 /CH 4 Selection factor α = (V) CO2 /V CH4 ) Rear end of membrane/(V) CO2 /V CH4 ) Front end of membrane, CO 2 Penetration of p = V CO2 /S*P，V CO2 Is CO 2 The flow rates in mol/s are shown in Table 1.
TABLE 1
As can be seen from Table 1, the composite membranes prepared in examples 1 to 4 are paired with CH 4 /CO 2 The mixed gas shows higher selectivity and permeation flux.
Claims (1)
1. Single-walled carbon nanotube-metal hybrid AlPO 4 -5 molecular sieve composite membrane in separation of CH 4 /CO 2 The application of the mixed gas is characterized in that the single-walled carbon nanotube-metal hybrid AlPO 4 The preparation method of the-5 molecular sieve composite membrane comprises the following steps:
1) Preparation of a synthetic solution:
taking an aluminum source, a phosphorus source, an organic template agent and deionized water as raw materials, wherein the molar composition of the raw materials of a reaction system is as follows by oxide: 1Al 2 O 3 :aP 2 O 5 :bTemplate:cH 2 dX, a = 0.8-1.3, b = 0.15-1, c = 45-1000, d = 0.075-0.3, X is transition metal salt; the phosphorus source is phosphoric acid with the mass percentage concentration of 85 percent; the aluminum source is aluminum isopropoxide or aluminum sulfate; the organic template is selected from tetrapropylammonium hydroxide and tetrapropylammonium bromide, and the transition metal X is selected from Fe or Ni;
according to the above dosage, under the stirring condition, gradually adding the weighed transition metal salt and the weighed aluminum source into the phosphoric acid water solution in sequence, and continuously stirring until the transition metal salt and the aluminum source are completely dissolved; then under the stirring state, dropwise adding the organic template agent into the mixed solution, uniformly stirring, and finally adjusting the pH of the reaction solution to 2.0-6.5 to obtain a synthetic solution;
2) Preparation of metal hybrid AlPO on ceramic carrier surface 4 -5 molecular sieve membrane
Taking a sheet-shaped porous ceramic material with the surface modified by PVA as a carrier, putting a synthetic fluid and the carrier into a tetrafluoro hydrothermal synthesis reaction kettle, ensuring that the synthetic fluid submerges the surface of the carrier, then putting the sealed reaction kettle into a drying oven heated to 160-200 ℃, reacting for 24-100 hours at the temperature, naturally cooling the reaction kettle to room temperature after the reaction is finished, taking out a sample, washing the sample to be neutral by using distilled water, drying the sample overnight under the drying oven 333K, detecting the completeness of the synthesized molecular sieve membrane, and carrying out secondary synthesis on an unqualified person until the product is qualified; the surface of the flake porous ceramic material modified by PVA is that a layer of structure directing agent PVA is uniformly coated on the surface of the flake porous ceramic material;
3) Single-walled carbon nanotube-metal hybrid AlPO 4 -5 preparation of molecular sieve membrane
Adopting positive polarity streamer discharge technology to hybridize the metal prepared in the step 2) with AlPO 4 -5 molecular sieve membrane is placed in self-made positive polarity streamer discharge electric field, and the sheet membrane body is ensured to be placed perpendicular to the electric field direction, and H is introduced under the condition of 250-350 DEG C 2 O/N 2 Mixed atmosphere, N 2 And H 2 O volume ratio is 1:10, the flow rate of the mixed gas is 1-100ml/min, the mixed atmosphere is excited to generate high-energy H free radicals under the conditions of 1kV pulse voltage, 10 mus pulse width and 50 pulses per second pulse frequency, and metal hybrid AlPO is utilized 4 5, treating for 12-48 hours to prepare the organic template agent in the pore canal of the molecular sieve membrane into the single-walled carbon nanotube, and finally preparing the single-walled carbon nanotube-metal hybrid AlPO 4 -5 composite molecular sieve membrane.
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| CN101941691A (en) * | 2010-09-21 | 2011-01-12 | 上海大学 | Preparation method of single-walled carbon nanotube |
| CN102583437A (en) * | 2012-03-08 | 2012-07-18 | 中国科学院广州能源研究所 | Preparation method for CNT (carbon nano tube)-SAPO (silicoaluminophosphate)-5 molecular-sieve composite membrane |
| WO2017158414A1 (en) * | 2016-03-16 | 2017-09-21 | Sabic Global Technologies B.V. | Synthesis of sapo-34 and use in chloromethane to olefins reactions |
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