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Plasma plasma and ten catalysts have different effects on the conversion of methane to carbon dioxide

Plasma plasma and ten catalysts have different effects on the conversion of methane to carbon dioxide

Plasma plasma and ten catalysts have different effects on the conversion of methane to carbon dioxide: Transition metal oxides are an important class of catalysts in industrial catalysts, and the heterogeneous catalytic reactions they participate in are usually carried out by the acid-base action or redox action of the catalyst. The research results of oxidative coupling of methane (OCM) under common catalytic conditions or under the combined action of plasma plasma catalysis show that most transition metal oxide catalysts have certain catalytic activity. Combined with previous studies on plasma plasma catalysis Working experience in methane dehydrogenation reaction under the action of selected transition metals such as Mn, Fe, Co, Ni and W to prepare their supported metal oxide catalysts, and research on CO2 oxidation under the combined action of supported transition metal oxide catalysts and plasma plasma Catalytic activity in the reaction of CH4 to C2 hydrocarbons. The order of methane conversion under the combined action of ten transition metal oxide catalysts such as NiO/Y-Al2O3 and plasma plasma is as follows: NiO/Y-Al2O3>ZnO/Y-Al2O3≈MoO3/Y-Al2O3>Re2Q7/Y-Al2O3>TiO2/7-Al2O3≈Cr2O3/Y-Al2O3≈Mn2O3/Y-Al2O3>Na2WO4/Y-Al2O3≈FeO3/ Y-Al2O3>Co2O2/Y-Al2O3. The order of carbon dioxide conversion rates is: Ni0/Y-Al2O3>TiO2/Y-Al2O3>Co2O3/Y-Al2O3> Na2WO4/Y-Al2O3≈Fe2O3/Y-Al2O3>Re2O7/Y-Al2O3≈Cr2O3/Y-Al2O3>Mn2O3/Y-Al2O3≈MoO3/ Y-Al2O3>ZnO/Y-Al2O3. It can be seen that under the same experimental conditions, the above ten catalysts and plasma plasma have different effects on the conversion of methane and carbon dioxide, and are different from the conversion of methane and carbon dioxide under the action of pure plasma (26.7% and 20.2%, respectively). NiO/Y-AL2O3 combined with plasma gave higher methane and carbon dioxide conversions (32.6% and 34.2%, respectively), while Co2O3/Y-Al2O3 and ZnO/Y-Al2O3 gave lower methane and carbon dioxide conversions rate (22.4% and 17.6%, respectively), the former is 10.2% and 16.6% higher than the latter, respectively. It shows that the catalysts participate in the C-H bond and C-O bond cleavage process of methane and carbon dioxide to different degrees.

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Plasma processor plasma surface treatment for automotive interior headlights applications

Plasma processor plasma surface treatment for automotive interior headlights applications

Plasma processor plasma surface treatment for automotive interior headlights applications: The plasma treatment machine has a good cleaning effect on surface cleaning, and can remove the release agent on the surface, and its activation process can ensure the quality of the subsequent bonding process and coating process. For coating treatment , the surface properties of the composites can be further improved. Using this plasma technology, materials can be efficiently surface pretreated according to specific process requirements. Plasma is a collection of positively charged positive particles and negative particles (including positive ions, negative ions, electrons, free radicals and various active groups, etc.) Body is the fourth state-plasma state in which matter exists in addition to solid, liquid and gaseous states. Application of plasma processor in automobile interior manufacturing process: The car interior mainly includes the following subsystems: dashboard system, sub-dashboard system, door trim, roof, seat, pillar protection system, other cab interior systems, cab air circulation system, trunk assembly, engine compartment Control systems, carpets, seat belts, airbags, steering wheels and interior lighting, car interior acoustic systems. Due to the complex composition of automotive interior materials, including various polymers, metals, semiconductors, rubber, leather, circuit boards, etc. This leads to major problems in coating, bonding and printing. To facilitate coating and printing, manual sanding has been widely used in the past. Due to the way, the efficiency is low, which seriously affects the external beauty of the interior. Using hot melt glue and other adhesives to prevent the glue from opening the water will only prevent the glue from being opened to a certain extent. It cost a lot of money, and once it was degummed, it still had complaints or returns. The energy of the particles in the plasma produced by the plasma processor is usually about several to tens of electron volts, which is greater than the bond energy of the polymer material (several to ten electron volts), which can completely break the chemical bonds of organic molecules and form new ones. But it is much lower than high-energy radiation, it only involves the surface of the material, there is no wear, and it does not affect the structure of the material itself.   Plasma processor plasma surface treatment headlights: Almost all headlamps are glued to meet leak-proof requirements between the lens and the housing. If cold glue works properly by virtue of the combination of art and its own price advantage, it can get cheap and high quality glue bond. The pretreatment of the low temperature plasma surface makes this possible, and the atmospheric pressure low temperature plasma processor makes this process possible.

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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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Catalytic activity of supported transition metal oxide catalysts under plasma plasma

Catalytic activity of supported transition metal oxide catalysts under plasma plasma

Catalytic activity of supported transition metal oxide catalysts under plasma plasma: According to the analysis results of the conversion reaction of CO2 oxidation of CH4 under the action of pure plasma plasma, refer to the relevant literature on the reaction of CO2 oxidation of CH4 to C2 hydrocarbons under the action of catalysis. It can be considered that in the plasma-catalyzed co-activated CO2 oxidation of CH4 to C2 hydrocarbons, the methane CH bond is broken mainly through the following pathways: 1. The inelastic collision of CH4 and high-energy electrons; 2. The activation of CH4 by reactive oxygen species; 3. The adsorption of CH4 by the catalyst Molecules, activate the C-H bond, causing the C-H bond to break. The conversion pathway of carbon dioxide is as follows: 1. The inelastic collision between CO2 molecules and high-energy electrons; 2. The active species such as CHx and H in the system activate CO2; 3. The catalyst adsorbs CO2 molecules, activates the C-0 bond, and promotes the cleavage of the CO bond to generate CO. and active O atoms. Obviously, pathway 3 is undoubtedly important for the conversion of CH4 and CO2 under the combined action of plasma catalysis. The activation of catalysts in plasma plasma mainly depends on collision with high-energy electrons. Due to the differences in the properties of catalysts, the catalysts have different activities, and have different adsorption and activation capabilities for methane and carbon dioxide. It can be seen from the above test results that NiO/Y-Al2O3 has strong adsorption, activation methane and carbon dioxide ability under the same plasma, so the conversion rate of CH and CO2 is high. On the contrary, Co2O3/Y-Al2O3 has weak ability to adsorb and activate methane, and the conversion rate of CH4 is low; Zn0/Y-Al2O has weak ability to adsorb and activate carbon dioxide, resulting in low CO2 conversion rate.  Under the action of plasma, according to the yield of C2 hydrocarbons, the catalytic activity sequence of supported transition metal oxides is: Na2WO4/Y-Al2O3>Cr2O3/Y-Al2O3≈Fe2O3/Y-Al2O3>TiO2/Y-Al2O3≈NiO/ Y-Al2O3≈Mn2O3/Y-Al2O3>Co2O3/Y-Al2O3>ZnO/Y-Al2O3≈MoO3/Y-Al2O3≈Re2O7/Y-Al2O3 According to the level of CO yield, the order of catalytic activity of supported transition metal oxides for: NiO/Y-Al2O3> TiO2/Y-Al2O3>Re2O3/Y-Al2O3≈Fe2O3/Y-Al2O3≈Co2O3/Y-Al2O3>MoO33/Y-Al2O3≈ZnO/Y-Al2O3≈Mn2O3/Y-Al2O3>Na2WO4/ Y-Al2O3≈Cr2O3/Y-A12O3. The experimental results show that the co-action of plasma plasma and supported transition metal oxide catalysts has different effects on the formation of C2 and CO. Na2WO4/Y-Al2O3 has higher C2 hydrocarbon yield (17.8%); NiO/Y-Al2O3 has higher CO yield (53.4%). Re2O7/Y-Al2O3 has a lower yield of C2 hydrocarbons (8.8%), and Cr2O3/Y-Al2O3 has a lower yield of CO (34.5%). Under the action of plasma catalysis, the reaction product is mainly formed by the recombination of active species on the surface of the third body, that is, C2 hydrocarbons are formed by the recombination of CHx on the surface of the third body, and CO is directly formed by the decomposition of carbon dioxide or C and O ( Oxygen-containing) actives are formed by recombining two pathways on the surface of the third body. Obviously, the adsorption capacity of the catalyst to various free radicals in the reaction system and whether the adsorption site is suitable will affect the yield of the reaction products C2 hydrocarbons and CO. For the Na2WO4/Y-Al2O3 catalyst, the yield of C2 hydrocarbons is much higher than other catalysts. The possible reason is that the surface of the catalyst is easy to attach CHx radicals, and the adsorption site is appropriate, which leads to the increased probability of CHx radicals coupling to generate C2 hydrocarbons. For NiO/Y-Al2O3, in addition to the higher CO2 conversion rate and the combination of C and O in the system, the CO2 yield is higher, and the active O2 adsorbed on the catalyst when the CHx radical is adsorbed on its surface. Atomic oxidation to generate CO is also a more important reason. The effect of NiO loading on the yields of 2 hydrocarbons and CO was investigated under the same experimental conditions. With the increase of NiO loading, the C2 hydrocarbon yield decreased and the CO yield increased. When the NiO loading was 40%, the reaction system had No C2 hydrocarbons can be detected, which confirms from the side that there is a CHx radical oxidation process on the surface of the catalyst in the reaction of CO2 oxidation of CH4 to C2 hydrocarbons when plasma plasma and NiO/Y-Al2O3 catalyst work together. Therefore, for the target product of the study, Na2WO4/Y-Al2O3 should be selected to generate C2 hydrocarbons, while NiO/Y-Al2O3 is more favorable for the formation of CO. The purpose of adding a catalyst for CO2 oxidation and CH4 conversion under the action of plasma is to improve the yield of C2 hydrocarbons with higher economic value. Therefore, improving the C2 hydrocarbon selectivity and C2 hydrocarbo

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Under the action of plasma plasma, the supported lanthanide oxide catalyst CO2 oxidizes CH4 to C2

Under the action of plasma plasma, the supported lanthanide oxide catalyst CO2 oxidizes CH4 to C2

Under the action of plasma plasma, the supported lanthanide oxide catalyst CO2 oxidizes CH4 to C2: The supported lanthanide oxide catalysts have good OCM reactivity. In the catalytically activated CO2 oxidation of CH4 to C2 hydrocarbons, La2O3/ZnO gave a C2 hydrocarbon selectivity of up to 97% (the methane conversion rate was 2.1% at 850 °C). The study by Maraffee et al. , the La2O3-based catalyst gave higher CH4 conversion (27.4%) and C2 hydrocarbon yield (10%). Therefore, this study focused on the catalytic effect of five supported lanthanide oxide catalysts, La, Ce, Pr, Sm, and Nd, on the reaction of CO2 oxidation of CH4 to C2 hydrocarbons under the action of plasma. Under a certain plasma effect, the supported lanthanide oxide catalysts all showed a certain ability to activate CH4 and CO2. As a result of the combined action of lanthanide catalyst and plasma, the conversion rate of CH4 is 24%~36%; the conversion rate of carbon dioxide is 18%~22%. The experimental results show that under the action of plasma, different lanthanide catalysts have great differences in the activation ability of CH4, while the ability to activate carbon dioxide is similar (the CO2 conversion rate under the action of pure plasma is similar to 20%). According to the experimental fact that lanthanide catalysts have certain catalytic activity under pure catalytic conditions. It can be speculated that under the action of plasma, the catalyst can participate in the C-H bond cleavage process of methane through surface reaction. For CH4 activation: There are differences in the ability of lanthanide catalysts and plasma to activate CH through the joint action. The order of their joint action ability is as follows: Nd203/Y-Al203 > CeO2/Y-Al203 > Sm203/Y-Al203 > Pr2O11/Y -Al203 > La2O3/Y-Al2O3. According to the C2 hydrocarbon selectivity, the order of catalyst activity is: La2O3/Y-Al2O3>CeO2/Y-Al203≈Pr2O11/Y-Al203>Sm203/Y-Al2O3>Nd203/Y-Al2O3. Comparing the results of C2 hydrocarbon selectivity with the effect of lanthanide catalysts on C2 hydrocarbon yield, the order of the two is basically the same. The performance is higher than 70%, so the C2 hydrocarbon yield is higher than other rare earth catalysts. This is consistent with the high C2 hydrocarbon selectivity of La2O3 catalyst under pure catalytic conditions. However, lanthanide catalysts have little effect on the distribution of C2 hydrocarbon products, and C2H2 is the main C2 hydrocarbon product.

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Plasma plasma and lanthanide catalytic supported transition metal oxide catalyst activity

Plasma plasma and lanthanide catalytic supported transition metal oxide catalyst activity

Plasma plasma and lanthanide catalytic supported transition metal oxide catalyst activity: Under the combined action of plasma plasma and lanthanide catalyst, the yield of C2 hydrocarbon and CO has a certain relationship with the atomic number of lanthanide catalyst, that is, with the increase of element atomic number, the yield of C hydrocarbon gradually decreases, and the yield of CO gradually increases. This shows that under the plasma atmosphere, the lanthanide catalysts have differences in adsorption selectivity and adsorption capacity for various free radicals in the system. The La2O3/Y-Al2O3 catalyst adsorbs methyl radicals and promotes the generation of C2 hydrocarbons; different from the La203/Y-Al2O3 catalyst, the Nd2O3/Y-Al2O3 catalyst tends to adsorb oxygen-containing radicals, and the methyl radicals on the catalyst surface Easily oxidized by oxygen-containing free radicals to form CO. It is worth noting that in the reaction of CO2 oxidation of CH4 to C2 hydrocarbons, CeO2/Y-Al203 combined with plasma showed better catalytic activity, which was similar to CeO2/Y-Al203 in the catalytic methane oxidation coupling reaction. The roles of sm2O2/Y-Al2O3 are obviously different. It is generally believed that CeO2/Y-Al2O3 is an excellent catalyst for the complete oxidation of methane to CO, which is not conducive to the formation of C2 hydrocarbons. Similarly, although Sm2O3/Y-Al2O3 is an excellent catalyst for the oxidative coupling reaction of methane, but in plasma plasma Its catalytic activity is not obvious in bulk atmosphere. This shows that the co-action mechanism of plasma and catalyst is not the same as that of pure catalysis, so it is necessary to further study the co-action mechanism of plasma plasma and catalyst.

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