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Catalytic activity of plasma supported alkaline earth metal oxide catalysts

Catalytic activity of plasma supported alkaline earth metal oxide catalysts

Catalytic activity of plasma supported alkaline earth metal oxide catalysts: The research on the reaction of CO2 oxidation of CH4 to C2 hydrocarbons under the combined action of plasma plasma and carrier shows that the acidic carrier Y-Al2O3 has a high methane conversion rate (43.4%), but the C2 hydrocarbon selectivity is low (30.6%): basic carrier MgO has a low methane conversion (17.8%), but a high C2 hydrocarbon selectivity (57.4%). If MgO is loaded on Y-Al2O3, can a higher C2 hydrocarbon selectivity be obtained on the basis of maintaining a certain methane conversion rate? Wang and Ohtsuka used the catalytic activation method to study the reaction of CO2 oxidation of CH to C2 hydrocarbons. The results show that some alkaline earth metal oxides such as CaO have high catalytic activity, which can improve the C2 hydrocarbon selectivity to a certain extent. The reaction of CO2 oxidation of CH4 to C2 hydrocarbons under the action of MgO/Y-Al2O3, CaO/Y-Al2O3, SrO/Y-Al2O3 and BaO/Y-Al2O3 was investigated under plasma conditions (Table 4-2). Compared with the result of Y-Al2O3 on the carrier, the CH conversion rate was decreased, but the C2 hydrocarbon selectivity was increased by more than 40 percentage points, indicating that the catalytic activity can be improved by loading basic active components on the acidic carrier. Under certain plasma conditions, the CH4 conversion and C2 hydrocarbon yield have a certain relationship with the basicity of MgO, CaO, SrO and BaO, that is, the basicity helps to improve the CH4 conversion and C2 hydrocarbon yield. For alkaline earth metal oxides, the basicity increases with increasing atomic number, so BaO/Y-Al2O3 and plasma can work together to obtain higher C2 hydrocarbon yields. Therefore, the catalytic activity sequence of the supported alkaline earth metal oxide catalysts under plasma ion conditions is BaO/Y-Al2O3 > SrO/Y-Al2O3 > CaO/Y-Al2O3 > MgO/Y-Al2O3. The effect of alkaline earth metal oxides on the distribution of C2 hydrocarbon products shows that they have little effect on the distribution of C2 hydrocarbon products. Acetylene is the major C2 hydrocarbon product. Table 4-2 Effects of alkaline earth metal oxide catalysts on the reaction (unit: %) Catalyst Xat Xco, sc. Yc Yco Y-Al2O3 43.4 16.7 30.6 13.4 37.1 MgO/Y-Al2O3 24.0 20.2 62.9 15.1 33.9 CaO/Y-Al2O3 24.4 19.3 64.3 15.7 34.4 SrO/Y-Al2O3 24.6 19.3 66.2 16.3 34.2 BaOr/Y-Al2O3 26.4 19.4 63.3 16.7 35.6 BaO loading and catalyst calcination temperature have a certain influence on the catalytic activity of supported alkali metal oxide catalysts. When the loading varies from 5% to 20%, with the increase of BaO loading, the conversion rates of CH4 and CO2 show the same trend. Peak-to-peak variation, peak high at 10% load. The yields of C2 hydrocarbons and CO basically changed in peak shape. This shows that the increase of BaO loading within a certain range is beneficial to improve the catalytic activity, but too high loading will lead to the accumulation of BaO on the surface of Y-Al2O3, which reduces the catalytic activity of the catalyst. The calcination temperature of the catalyst has an effect on the size and surface morphology of the active particles of the catalyst, and affects the reactivity of the catalyst to a certain extent. Generally speaking, at lower calcination temperature, it is easy to obtain highly dispersed small particles, and the lattice structure is often defective; at higher calcination temperature, larger particles are obtained. In the calcination temperature range of 400～800℃, the research on the effect of calcination temperature on the catalytic activity of 10%-BaO/Y-Al2O3 shows that when the calcination temperature is 400℃, the conversion rates of CH4 and CO2 are slightly higher than other calcination temperatures, but C2 hydrocarbons The low selectivity of C2 resulted in a decrease in the yield of C2 hydrocarbons. This is because at this temperature, the Ba(NO3)2 supported on the surface of Y-Al203 is not completely decomposed, which can be confirmed by the X-ray diffraction (XRD) spectrum of the sample; when the calcination temperature is between When the temperature is between 500 and 800 °C, the catalytic activity has little effect; when the reaction temperature is higher than 800 °C, Y-Al2O3 is transformed into δ-A12O3, and the reaction activity decreases.

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Hydrophobic reaction between TMCS and Southwest birch wood surface in plasma environment

Hydrophobic reaction between TMCS and Southwest birch wood surface in plasma environment

Hydrophobic reaction between TMCS and Southwest birch wood surface in plasma environment:          Wood is a renewable green material and biological resource among the four major materials (steel, cement, wood and plastic). Decoration, paper, furniture, packaging and agriculture. However, due to the presence of many free hydroxyl groups in chemical components such as cellulose and hemicellulose in wood components, they have strong hygroscopic ability under certain temperature and humidity conditions, and moisture absorption will lead to shrinkage and swelling of wood and poor dimensional stability. , discoloration and susceptibility to fungi and insects.        Wood is deteriorated due to the influence of light, heat, water and other external environments. The deterioration generally starts from the surface and then gradually develops to the interior. Therefore, appropriate physical or chemical methods are used to treat the surface of the wood to avoid the occurrence of these inherent defects. Particularly important. Southwest birch is a fast-growing wood species with high economic value in southwest China. It has fine structure, beautiful patterns and good processing performance. It is an excellent wood for flooring and furniture. Using volatile trimethylchlorosilane (TMCS) as the monomer, the silyl group is introduced into the surface of the wood in a plasma environment to silanize the wood surface, endow the wood surface with hydrophobic properties, and expand the use range of wood and improve its durability. Plasma treatment is a dry process that requires less chemicals and the reaction is carried out at a lower temperature, so plasma surface treatment is considered to be an economical and environmentally friendly treatment method. The cell wall surface of untreated wood left traces of torn wood fibers during the slicing process, and the rest of the area was smooth. However, granular structures appeared on the surface of the wood cell wall treated with TMCS plasma, and these granular structures evenly covered the surface of the cell wall, which fully indicated that TMCS was successfully polymerized and deposited on the surface of the wood under the plasma environment. There are two ways to improve and change the hydrophobicity of the material surface, one is to increase the roughness of the surface of the hydrophobic material; the other is to modify the low surface energy material on the rough surface, and the latter gradually becomes the mainstream. The static contact angle test on the untreated Southwest birch wood surface showed "zero", that is, the water droplets wet the wood surface immediately after contacting the wood surface, but the wood surface modified by TMCS plasma had better hydrophobicity and hydrophobic stability sex. With the increase of the treatment power, the contact angle showed a decreasing trend, and the same results were obtained when the surface of southern ponderosa pine wood was treated with hexamethyldisiloxane plasma, indicating that low power is beneficial to the formation of the surface of the wood. Hydrophobic films, and the increase in power will aggravate the oxidation resulting in an increase in the concentration of oxygen-containing functional groups on the surface. The surface of Southwest birch wood was modified with TMCS in a plasma environment. After 28 days of continuous aging under different temperature and humidity conditions, the wood surface still showed stable hydrophobic properties, and the decrease in contact angle after aging was only 1.9°~3.7°. ° between.   In the plasma environment, TMCS reacted with the surface of Southwest birch wood, and silyl groups were introduced into the surface of the wood, and the content of silicon reached 22.82%. The treated wood surface formed a uniform granular structure, which significantly improved the hydrophobicity and hydrophobic stability of the wood surface.

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Co-activation of CH4 and CO2 to C2H4 by plasma plasma and Pd-La203/Y-Al203 catalyst

Co-activation of CH4 and CO2 to C2H4 by plasma plasma and Pd-La203/Y-Al203 catalyst

Co-activation of CH4 and CO2 to C2H4 by plasma plasma and Pd-La203/Y-Al203 catalyst: The supported Pd catalyst is a catalyst for the hydrogenation of acetylene, and the micro-loaded Pd can reduce C2H2 to C2H4 or C2H6. When increased to 0.1%, the ethane mole fraction increased from 24.0% to 61.7%. The ethylene mole fraction decreased from 72.3% to 22.1%, while the C3 product mole fraction increased significantly. Therefore, in the reaction of plasma plasma and catalyst co-activated CO2 to oxidize CH4 to C2H4, as long as a trace amount of Pd is loaded on the catalyst, a C2H4 product with greater economic added value can be obtained. The research results of CO2 oxidation of CH to C2 hydrocarbons under the combined action of plasma plasma and catalyst show that La2O3/Y-Al203 can significantly improve the selectivity of C2 hydrocarbon products. Under the same plasma conditions, its C2 hydrocarbon product selectivity is higher than that of Y-Al203. It is higher than 40%, so the yield of C2 hydrocarbon products is high; although the supported metal catalyst Pd/Y-Al2O3 has little effect on the yield of C2 hydrocarbon products, it can obviously change the distribution of C2 hydrocarbon products, and the micro-loaded Pd can obviously Increase the mole fraction of C2H2 in the C2 hydrocarbon product. To this end, the co-activated CO2 oxidation of CH4 to C2H4 by plasma plasma and Pd-La2O3/Y-Al2O3 was studied, and the effects of parameters such as active component loading, feed gas composition, and energy density on the reaction were investigated. When the La2O3 loading was 2%, the C2 hydrocarbon selectivity increased from 30.6% to 72%. Although the methane conversion rate decreased from 43.4% to 24%, the C2 hydrocarbon yield still increased from 13.4% to 17.6%. La2O3 improves the CO2 conversion, but the CO yield decreases: when the La2O3 loading is changed in the range of 2% to 12%, the CH4 conversion and C2 hydrocarbon yield slightly change in peak shape, but the CO2 conversion and CO yield change slightly. The effect of Pd on the conversion rate of CH4 and CO2, and the yield of C2 hydrocarbons and CO basically has no effect when the loading of La2O3 reaches 12%. However, the Pd loading has a great influence on the distribution of C2 hydrocarbon products. When the Pd loading amount is 0.01%, the mole fraction of C2H4 in the C2 hydrocarbon products rises to 78%, that is, the C2 hydrocarbon products are mainly C2H4. C2H2 was detected but C3H8 was produced. When the Pd loading increased from 0.01% to 1%, the mole fraction of C2H4 in the C2 hydrocarbon product gradually decreased, while the mole fraction of C2H6 in the C2 hydrocarbon product gradually increased, indicating that the addition of Pd in ​​the La2O3/Y-Al2O3 catalyst was further increased. It can not increase the mole fraction of C2H4 in C2 hydrocarbon products, but promote the conversion of C2H4 to C2H6 and increase the mole fraction of C2H6 in C2 hydrocarbon products. The recommended loadings of active components Pd and La2O3 are 0.01% and 5%, respectively, that is, the catalyst is 0.01%Pd-5%La2O3/Y-Al2O3.

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Research on the application of low temperature plasma radical chemical reaction in polysilicon industry

Research on the application of low temperature plasma radical chemical reaction in polysilicon industry

Research on the application of low temperature plasma radical chemical reaction in polysilicon industry: A chemical reaction is a recombination at the level of atoms or groups of atoms, which requires the necessary activation energy for the reaction from the outside world. Compared with plasma, the reactants produced in industry are mostly in a dense condensed state. Most of the participating gases are dense layers of "high concentration", which makes it difficult to continuously transfer large excitation energy to the reaction system, and some chemical reactions that require extremely large activation energy are difficult to achieve under conventional technical conditions. There is a close connection between chemistry and physics. Microscopic forms such as electron movement, interatomic interaction force, and excitation and ionization of atoms and molecules in molecules determine the physicochemical properties and chemical reaction capabilities of substances. Therefore, applying physical methods to change the state of matter can lead to chemical changes or affect the progress of chemical reactions. For this reason, the electric field directly transfers energy to the gas molecules in the reaction chamber, generating electrons with sufficient energy to inelastically collide with the gas molecules, transferring almost all the energy of the electrons to the gas molecules participating in the reaction, so that a large number of photons are generated in the gas in the reaction chamber. , electrons, ions, free radicals and active atoms excited state atoms and active molecules provide extremely active active particles for their chemical reactions, thereby making many chemical reaction conditions milder and improving chemical reaction efficiency. In nature, substances exist in solid state, liquid state and gaseous state. Among them, solid particles are closely bound together, followed by liquid state, and gaseous state is dispersed. To achieve the transformation of substances from a dense to a dispersed aggregate state, it is necessary to provide additional energy to destroy the larger binding energy between the original particles. In the same way, when the substance is in a gaseous state, it continues to provide energy to form the ionization of the gaseous substance particles to form a plasma. The difference between a low temperature plasma and a high temperature plasma is the temperature of the ions and the ion channel. The electron motion temperature of low temperature plasma is as high as 10~10K, while the ion and neutral ion temperature of gas is close to the ambient temperature, which is much lower than the electron motion temperature. Therefore, low temperature plasma is also called non-equilibrium plasma. Low temperature plasma can be generated under normal temperature and pressure, and its industrial application prospect is broad. The test data shows that the power parameters have a great influence on the primary conversion rate of STC. The lower the power frequency and the higher the voltage within a certain range, the more conducive to the chlorosilane hydrogenation reaction. The low-temperature plasma generator generated by the power frequency through the DBD discharge method is safe, reliable, economical, environmentally friendly and easy to implement. For the promotion effect in the hydrogenation of silicon tetrachloride, the primary conversion efficiency of STC of more than 5% can be achieved by using plasma assistance under normal temperature and pressure conditions. Plasma contains a large number of photons, electrons, ions, free radicals, and active atomic excited state atomic excited state molecules and active molecules, etc., which provide extremely active active particles for chemical reactions, so that many usually cannot occur or require extremely harsh conditions to occur. The chemical reaction becomes easy to carry out at close to room temperature, which provides a new realization method for chemical reaction. For the polysilicon chemical industry, considering hydrogenation, vapor deposition and other processes in terms of energy consumption control and efficiency improvement, the use of plasma to promote the reaction process has great practical value and scientific research value.

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Introduction to the characteristics of the plasma surface treatment equipment that increases the bonding of the atmospheric plasma cleaning machine:

Introduction to the characteristics of the plasma surface treatment equipment that increases the bonding of the atmospheric plasma cleaning machine:

Introduction to the characteristics of the plasma surface treatment equipment that increases the bonding of the atmospheric plasma cleaning machine: Atmospheric plasma cleaning machine surface treatment equipment, that is, single-electrode plasma processor, generates low-temperature plasma in low-temperature plasma, and its ion and electron energy can be as high as 7-10eV, which can process various polymer materials and glass ceramics, such as poly Propylene (PP), Polyethylene (PE), Polyvinyl Chloride (PUL), Propylene Oxide (PTFE/Teflon), Polystyrene (PS), ABS, P Ester (PET), Polyurethane (PUL), POM, Polyethylene Tetrafluoroethylene (PTFE/Teflon), vinyl, nylon, rubber, glass, plexiglass, ABS, etc. Even for extremely difficult polymer materials such as fluorine-containing plastics and silicone rubber, the surface tension can still reach 65~70 y/cm or higher after treatment, thereby improving its adhesion. The ionized gas produced by low pressure discharge (glow, corona, high frequency and microwave, etc.), under the action of the electric field, the free electrons in the gas are converted into high-energy electrons by the electric field, so how does this substance enable the plasma surface treatment equipment to be able to Improve its surface adhesion? The following will answer this question for you. Such high-energy electrons collide with molecules and atoms in the gas. If the energy of the electrons is greater than the excitation energy of the molecules or atoms, free radicals, ions and radiations with different energies that excite the molecules or atoms will be generated. Ion bombardment or implantation into the polymer surface results in bond breakage or introduction of functional groups to activate the surface to achieve modification. In the radio frequency low temperature plasma of the plasma surface treatment equipment, due to the high ion energy and electron energy of the single electrode, it can be designed into various shapes, especially

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The application of atmospheric plasma surface processor plasma cleaning machine on FPC board

The application of atmospheric plasma surface processor plasma cleaning machine on FPC board

The application of atmospheric plasma surface processor plasma cleaning machine on FPC board: As soon as the atmospheric plasma surface processor came out, it was welcomed and favored by the majority of industrial enterprises, because it can modify the surface physicochemically, which can improve the adhesion performance of the surface to a certain extent. Its role can be said to be quite large. The following will introduce which of these industries need to use atmospheric plasma surface processors. In the electronics industry, the plasma activation cleaning process is a key technology in the process of reducing costs and improving reliability. Before coating the circuit board on the chip printed circuit board, the plasma activation cleaning process is performed first. Electrostatic treatment can ensure the firm adhesion of the coating, while in the field of chip packaging, plasma cleaning machine cleaning technology is used, and atmospheric pressure or vacuum equipment can be used for treatment. Plasma treatment of plastic windows, due to the use of plasma treatment process, improves the surface properties of the material and makes the coatings more evenly distributed together, which not only makes the product look impeccable, but also greatly reduces the production process. Rejection rate. As we all know, the printing and packaging industry provides a wide variety of packaging boxes to customers. If it is not handled properly, it is easy to open the glue, which has a great impact on the profit of the company. If a plasma processor is used, the problem of glue opening can be effectively avoided, and the surface of various materials can be treated, which can greatly reduce grinding pollution, save glue consumption to a certain extent, and save costs at the same time. In the digital industry, it is also necessary to use an atmospheric plasma surface processor. If it is used to spray the casing of digital products, it can make the bonding of the display screen more firm, and there will be no problem of glue opening, which can greatly improve the adhesion of the treated surface and effectively Prevent degumming of digital product casings. As the substrate of electronic components, the printed circuit board is electrically conductive, which presents a challenge to the processing of the printed circuit board by the atmospheric pressure process. Any surface pretreatment method, even if only a small potential is generated, will cause short circuits and thus damage. wiring and electronics. For this electronic application, the special performance of the atmospheric plasma surface treatment technology provides new possibilities for industrial applications in this field. In the manufacturing industry, it is also necessary to use a pneumatic plasma surface treatment machine. Knowing that the car must have good air tightness, the pneumatic atmospheric plasma surface treatment machine can be used to pretreat and spray some parts of the car, such as doors and windows, air conditioners, etc. Adhesive to increase the air tightness of the car, and has a good effect on waterproof and sound insulation. There are many metal products in the hardware industry. If the surface is modified with a processor, it can not only prolong its service life, but also greatly improve its wear resistance. With the development of high-sensitivity electronic components such as silicon, silicon, and high-performance semiconductors, atmospheric plasma surface processors have also been developed as a manufacturing process. The development of plasma technology in atmospheric environment provides a new application prospect for plasma cleaning, especially its fully automatic production. It can be seen that the application of air pressure plasma surface processor is very extensive, and in the near future, it may be used by more industries and the coverage will be wider. If you need to use it, you can buy it from regular manufacturers.

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