Disclosure of Invention
The invention provides a device and a method for preparing a metal catalyst by using plasma, wherein the prepared metal catalyst is uniformly dispersed on a carrier, and the device and the method are convenient to use, clean and environment-friendly.
An apparatus for preparing a metal catalyst using plasma, comprising: the device comprises a reaction chamber, wherein a metal plate electrode and a multi-needle electrode are arranged in the reaction chamber, the metal plate electrode and the multi-needle electrode are oppositely arranged, and a dielectric plate is pressed on the metal plate electrode in a pressing mode.
Further, the distance between the end part of the multi-needle electrode and the dielectric plate is 1-50 mm.
Furthermore, the curvature radius of the needles on the multi-needle electrode is 0.1-0.5 mm, and the density of the needles is 50-100 needles/dm2。
Further, the multi-needle electrode is made of stainless steel or other metals.
Further, the dielectric plate is quartz or ceramic, the area of the dielectric plate is not smaller than the metal plate electrode, and the thickness of the dielectric plate is 1-5 mm.
Further, the material of the reaction chamber is one of organic glass, quartz and stainless steel.
Further, still include electrode plate adjustment mechanism, electrode plate adjustment mechanism includes threaded rod, seal receptacle, packing ring and nut, the seal receptacle passes through the nut to be fixed on the reacting chamber, the metal plate electrode is fixed the tip of threaded rod, the threaded rod with seal receptacle threaded connection.
Further, the reaction chamber is provided with an air guide hole.
A method for preparing a metal catalyst using the above apparatus for preparing a metal catalyst using plasma, comprising the steps of:
step 1: completely immersing the catalyst support in a metal salt solution;
step 2: treating the catalyst carrier by adopting impregnation or ultrasonic impregnation;
and step 3: taking out the catalyst carrier and drying to obtain a catalyst to be treated;
and 4, step 4: uniformly placing the catalyst to be treated on the surface of the dielectric plate;
and 5: applying a high voltage to the multi-pin electrode and the metal plate electrode;
step 6: and corona discharge plasma is generated at the end part of the multi-needle electrode, and dielectric barrier discharge plasma is generated on one surface of the dielectric plate facing the multi-needle electrode, and the dielectric barrier discharge plasma all act on the surface of the catalyst to be treated to obtain a finished catalyst product.
Further, step 4 further comprises introducing a carrier gas from the gas guide hole.
The invention provides a device and a method for preparing a metal catalyst by using plasma, wherein the metal catalyst prepared by using the plasma is uniformly dispersed on a carrier, and the device and the method have the following advantages: firstly, the lower gas temperature of the plasma can avoid sintering and agglomeration of metal particles, inhibit the metal particles from diffusing into the carrier and enhance the interaction between the metal and the carrier; secondly, high-energy electrons in the plasma can be adsorbed on the surfaces of the metal particles, so that the metal particles are negatively charged and mutually repelled, and the dispersion degree of the metal particles is favorably improved; thirdly, high-energy particles in the plasma can rapidly decompose a catalyst precursor to rapidly nucleate metal ions; and fourthly, on a mesoscopic scale, the influence of relative contact behavior of the plasma can make the prepared metal catalyst structurally different from the catalyst prepared by the traditional method, so that the catalyst obtains better performance.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, an apparatus for preparing a metal catalyst using plasma, comprising: the reaction chamber 1 is internally provided with a metal plate electrode 2 and a multi-needle electrode 3, the metal plate electrode 2 and the multi-needle electrode 3 are oppositely arranged, a dielectric plate 4 is pressed on the metal plate electrode 2, and the reaction chamber 1 is provided with an air guide hole 5.
The reaction chamber 1 is made of insulating materials such as organic glass and quartz or metal materials such as stainless steel, the reaction chamber 1 is fixed and sealed by the bases up and down, the upper base and the lower base are fixed by bolts, the bases are provided with air guide holes 5, the air guide holes 5 can also be arranged on the side wall of the reaction chamber 1, and carrier gas such as inert gas such as argon and the like or gas such as hydrogen and oxygen and the like which can participate in the reaction can be introduced according to requirements. The multi-pin electrode 3 and the metal plate electrode 2 are respectively connected with the positive electrode and the negative electrode of a power supply, and the power supply can be a pulse power supply, a direct current power supply or an alternating current power supply. The range of the power voltage is 1kV to 40kV, and if the power voltage is pulse discharge, the frequency range is 100Hz to 10000 Hz; the voltage range of the discharge is preferably 15kV to 30kV, and the preferred frequency range of the pulse discharge is 1000Hz to 7000 Hz; the low-frequency pulse discharge is adopted, so that the energy consumption can be effectively reduced, and the preparation efficiency of the catalyst is improved.
The multi-pin electrode 3 is formed by arranging a plurality of pin electrodes on a metal base plate and directing the plurality of pin electrodes toward the metal plate electrode 2, the curvature radius of the pins on the multi-pin electrode 3 is 0.1-0.5 mm, and the density of the pins is 50-100/dm2The multi-needle electrode 3 is made of stainless steel or other metals.
The dielectric plate 4 is made of quartz, ceramics or the like, the area of the dielectric plate 4 is not smaller than that of the metal plate electrode 2, and the thickness of the dielectric plate 4 is 1-5 mm. The catalyst 6 to be treated is placed on the dielectric plate 4, the dielectric plate 4 is pressed against the metal plate electrode 2, the dielectric plate 4 prevents the discharge breakdown of the multi-needle electrode 3, maintains the corona discharge state of the multi-needle electrode 3, and can form dielectric barrier discharge at one end of the dielectric plate 4, and the catalyst 6 to be treated is surface-treated together with the corona discharge formed by the multi-needle electrode 3.
Further, the distance between the end of the multi-pin electrode 3 and the dielectric plate 4 is 1 to 50 mm. In the distance range, the multi-needle electrode 3 carries out corona discharge to treat the catalyst 6 to be treated, and when the distance between the end part of the multi-needle electrode 3 and the dielectric plate 4 is 3-20 mm, the corona discharge treatment effect is better.
Further, as shown in fig. 2, the apparatus further comprises an electrode plate adjusting mechanism 7, the electrode plate adjusting mechanism 7 comprises a threaded rod 71, a sealing seat 72, a washer 73 and a nut 74, as shown in fig. 3, the sealing seat 72 comprises a first cylinder 721 and a second cylinder 722 coaxially and fixedly connected with the first cylinder, through threaded holes are arranged in the first cylinder 721 and the second cylinder 722 and are matched with the threaded rod 71, the first cylinder 721 is arranged in the reaction chamber 1, an opening is arranged at the top of the reaction chamber 1, the diameter of the opening is larger than that of the second cylinder 722 and smaller than that of the first cylinder 721, the second cylinder 722 extends out from the opening at the top of the reaction chamber 1, threads are arranged outside the second cylinder 722 and are matched with the nut 74, the sealing seat 72 is fixed on the reaction chamber 1 through the nut 74, the washer 73 ensures the sealing between the sealing seat 72 and the reaction chamber 1, the multi-needle electrode 2 and the metal plate electrode 3 are fixed at the end, the threaded rod 71 is in threaded connection with the sealing seat 72, and the distance between the multi-pin electrode 2 and the metal plate electrode 3 can be adjusted.
The reaction chamber and the base can be made of insulating materials such as organic glass and quartz, metal materials such as stainless steel can be adopted, and when the metal materials such as stainless steel are adopted, the sealing seat is made of insulating materials such as nylon.
By rotating the threaded rod 71, the distance between the multi-pin electrode 2 and the metal plate electrode 3 can be changed. The distance between the multi-needle electrode 2 and the metal plate electrode 3 is adjusted, so that the discharge intensity between the two electrodes can be changed. The closer the distance between the multi-pin electrode 2 and the metal plate electrode 3 is, the higher the intensity of corona discharge and dielectric barrier discharge is at the same peak voltage.
As shown in fig. 4, a method for preparing a metal catalyst using the above apparatus for preparing a metal catalyst using plasma, comprises the steps of:
step 1: completely immersing the catalyst support in a metal salt solution;
step 2: treating the catalyst carrier by adopting impregnation or ultrasonic impregnation;
and step 3: taking out the catalyst carrier and drying to obtain a catalyst 6 to be treated;
and 4, step 4: uniformly placing a catalyst 6 to be treated on the surface of the dielectric plate 4;
and 5: applying a high voltage to the multi-pin electrode 3 and the metal plate electrode 2;
step 6: corona discharge plasma is generated at the end part of the multi-needle electrode 3, and dielectric barrier discharge plasma is generated on one surface of the dielectric plate 4 facing the multi-needle electrode 3 and acts on the surface of the catalyst 6 to be treated, so that a catalyst finished product is obtained.
Further, step 4 includes introducing a carrier gas through the gas guide hole 5.
The method comprises the following specific implementation processes:
the multi-needle electrode 3 adopts a needle with a curvature radius of 0.3mm and has 75 needles/dm2Evenly distributed, adopt the quartz plate that thickness is 3mm as dielectric plate 4, adopt organic glass to make reaction chamber 1, add the organic glass base from top to bottom and seal with the bolt fastening, set up air guide hole 5 on the base.
Mixing gamma-Al2O3The method comprises the steps of completely immersing the catalyst in an aqueous solution of nickel sulfate and cobalt sulfate, carrying out ultrasonic immersion for 30min, then drying the catalyst in an oven at 80 ℃ for 30min to obtain a catalyst to be treated, uniformly placing the catalyst to be treated on a dielectric plate 4 in a reaction chamber 1, setting the peak voltage of a power supply to be 25kV and the discharge frequency to be 5000Hz, and adjusting the distance between a multi-needle electrode 3 and the dielectric plate 4 to enable the multi-needle electrode 3 to be in a corona discharge state and to uniformly act on the surface of the catalyst to be treated, wherein the distance between the end part of the multi-needle electrode 3 and the dielectric plate 4 is 12 mm. The catalyst to be treated is subjected to discharge treatment under the parameters, corona discharge plasma is generated at the end part of the multi-needle electrode 3, dielectric barrier discharge plasma is generated on one surface, facing the multi-needle electrode 3, of the dielectric plate 4, the plasmas generated from the two aspects act on the surface of the catalyst to be treated, and the catalyst is obtained after 5min of discharge treatmentAnd (5) preparing a finished product.
To verify the efficacy of the finished catalyst, a verification experiment was performed. The obtained catalyst finished product is used for simulating the catalytic modification of the thickened oil, and the experimental result shows that the experimental temperature is 200 ℃, the oil-water volume ratio is 3: 1, after the catalyst is added, compared with the kinematic viscosity of oil without the catalyst, the kinematic viscosity is reduced by 54 percent, the heat value is improved by 4.1 percent, and the yield of light oil after catalytic reaction reaches 87 percent.
The invention adopts the corona-dielectric barrier discharge plasma form, and can effectively avoid the conversion from corona discharge to spark discharge in the discharge form compared with the traditional needle-plate corona discharge; compared with the traditional dielectric barrier discharge, the discharge form can generate more stable and uniform plasma. The method can prepare the catalyst uniformly in a large area in the process of preparing the catalyst by the plasma, and can effectively prevent the catalyst from being excessively sintered; meanwhile, researches find that the catalyst prepared by the method has more uniform particle size distribution, has better performance in the applications of thickened oil modification, hydrogen preparation and the like, and has stronger practical value and application prospect.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.