A method of manufacturing a textile catalyst on the substrate of the optical fibers

 

(57) Abstract:

The manufacture of textile catalyst on a substrate of glass fiber is impregnated substrate with a solution of salts of metals of variable valency or their mixtures with further drying at 105-120oS and annealing at 350-400oC. as the substrate material used fiberglass with a specific surface area of 0.2-5.0 m2/g and a specific pore volume of 0.1-0.25 cm3/year Achieved an increase of catalytic activity of textile catalyst and simplify the cooking process. 1 C.p. f-crystals, 1 table.

The invention relates to methods for producing catalysts for oxidation of organic and inorganic substances and can be used for the manufacture of catalysts for purification of exhaust gases from various plants, automobile exhausts from harmful impurities (such as carbon monoxide, condensed aromatic hydrocarbons and others).

Known [1] cell catalysts consisting of inert, durable, heat-resistant substrate, with the correct cell geometric structure and deposited on a substrate catalytically active layer, usually consisting of oxides of transition metals, metallisation is difficult access reactant to the active groups of the catalyst, catalysts work in interdiffuse the field that slows down the process and makes its regulation. Therefore, as a catalytically active layer is necessary to use highly potent compounds of the platinum group and still not achieved the activity that would, if it were not interdiffuse resistance. In addition, such materials have significant hydrodynamic resistance, which increases the operating costs of the pumping flow of the reactants through the catalytic reactor.

The solution to this problem can be used as a substrate of fibrous materials. Fibers have high mechanical strength, available, can be recycled conventional textile methods in a variety of easy to use forms with low hydraulic resistance (for example, a woven mesh, knitted bulk materials, nonwoven materials, and finally fiber having a large surface area, can accelerate mass transfer processes to facilitate the access of reactants to the catalytic groups, which leads to the transition processes in vneshnediffuzionnoe region, where in addition to higher speeds processesa a method of manufacturing a textile catalyst on a substrate of optical fibers [2], moreover, in this work we studied the oxidation of a mixture of CO, NOxC3H8C3H6in the presence of nitrogen, carbon dioxide and water vapor. The preparation of the catalyst occurs according to the following scheme. First is spinning fibers modified viscose method of viscose composition containing molecular chain of the polysilicon acid. The obtained fiber containing 70% cellulose and 30% silicic acid, is processed into textiles. Next is the burning of cellulose with simultaneous sintering of the ceramic particles at a temperature of 950oC, the content of SiO2in the fiber is 99.5%. The results of x-ray analysis shows that the fiber has a porous amorphous structure with a predominant pore size of 20 to 1000 , a specific surface area of 90 to 140 m2/g and a pore volume of 0.30 - 0.63 cm3/, Then a stage of impregnation of the textile samples alcohol solutions of nitrates of Co, Ni, Mn, (NH4)2Cr2O7or mixtures thereof depending on the desired composition of the catalytically active layer. Next, perform a stage of drying at room temperature for 12 hours and the stage of annealing to consolidate the active metal on inert the political layer. When this occurs the formation of metal oxides on the surface of the pores of the support. Since the rate of catalysis is not large enough, it is necessary the introduction of expensive platinum and palladium activators, which, after annealing textile catalysts were processed alcohol solutions of H2PtCl6H2O, PdCl2with a repeat cycle of drying at room temperature for 12 hours and calcination at a temperature of 500 to 700oC. the Best results in speed catalytic process obtained on Co and Co - Pt-containing catalyst.

The prototype disadvantages are the complexity of the process of preparation of the catalyst and slow catalysis. Slow catalysis is associated with the following. The substrate material due to the nature of its preparation is highly porous, the majority of the active metal is deposited inside the pores [2], which complicates the transport of reactants to the catalytic centers and slows down the reaction rate. Indirect confirmation of this is that found in [3] reaction orders for oxygen and oxidizable substance were fractional at all catalysts except for the highly active Pt-containing catalysis is key reactions indicate unequal contribution to the oxidation reaction of the inner and outer layers of the catalyst except for the high activity of platinum-containing samples the main part of the substance has time to react in the surface layers of the catalyst. Thus the porous structure of the substrate prevents the full use of the main advantages of fibrous catalysts - low interdiffuse resistance. Other ensuing disadvantage is the need to increase reaction rates, to introduce expensive activators - platinum group metals. At the same time to prevent loss of the compounds of the platinum group and their introduction should be implemented in the form of additional cycle of impregnation, drying and calcination. Another disadvantage is too high temperatures at the stage of annealing to consolidate the metal on an inert carrier component of the 500 - 700oC, which leads to excess energy. Another disadvantage of the use of the porous structure of the gel origin is the need for lengthy drying time after fiber impregnation - 12 hours, which is associated with the use of room temperature - 25oC and the use of alcohol solutions.

The technical result of the present invention is to increase the catalytic activity of textile catalyst and simplification of p is Bologna with a specific surface area of 0.2 - 5.0 m2/g and a specific pore volume of 0.1 - 0.25 cm2/g is impregnated with an aqueous solution of salts of metals of variable valency or their mixtures, stage drying is carried out at a temperature of 105 - 120oC, and the stage of calcination is at 350 - 400oC. in Addition, in the impregnating solution can be introduced activator ZnNO3.

An important indicator for catalysts obtained by the method of applying an active layer on the inert substrate is to consolidate the strength of the catalytically active part on the substrate, as in case of insufficient strength to cause exfoliation of the active layer from the substrate during operation with loss of catalytic activity. Exfoliation of the catalytically active layer from the substrate will lead to a sharp decrease in the activity of the catalyst. In the case of the prototype secure the strength of the oxide film was assured by the fact that the metal was deposited in the pores of the substrate. And in the case of the claimed invention, when the catalytically active film is on the surface of the fiber, the mode of preparation of the catalyst should be chosen so that there was no peeling of the active film from the substrate during operation. It was established experimentally that processesto depend on the temperature drying and calcination. The best results on the strength of fixing of the oxide film and the catalytic activity is obtained when the drying temperature 105 - 120oC and calcination at 350 - 400oC.

Use as activators Zn salts known in the technique [1], but they have not been used in the catalysts of the fibrous structure and the effect of increasing activity is not obvious.

Experimental studies have shown that the essential features are used as the substrate material fiberglass with a specific surface area of 0.2 - 5.0 m2/g and a specific pore volume of 0.1 - 0.25 cm3/g, as an impregnating solution is an aqueous solution of salts of metals of variable valency or their mixtures, the stage of drying at a temperature of 105 - 120oC, stage calcination at 350 - 400oC, in addition, in the impregnating solution at the stage of impregnation may be additionally introduced activator ZnNO3.

These distinctive features can refuse to be used as the substrate material of the optical fibers obtained modified viscose method further burning of the cellulosic substrate and sintering the particles of silicon oxide. The prototype option is lsout the fiber obtained by the method of the molten molding with the following characteristics: specific surface area of 0.2 - 5.0 m2/g, specific pore volume of 0.1 - 0.25 cm3/, Holding the stage of drying at a temperature of 105 - 120oC, stage calcination at 350 - 400oC allows to achieve such strength of fixing of the active layer on the fiber, in which the active layer will not become loose during operation with the fall of the catalytic activity.

High speed catalytic reactions allow to renounce the use of additional high-value platinum activators, replacing them with much cheaper compounds of zinc. In additional the case of the introduction of the activator ZnNO3can be added directly in the impregnating solution at the stage of impregnation, and not to enter another cycle of impregnation, drying and calcination as in the prototype.

A method of manufacturing a textile catalyst on the substrate of the optical fibers is as follows. Textile material fibreglass (for example, textile or knitted mesh, non-woven material) obtained by the method of rasplavlennogo molding with a specific surface area of 0.2 - 5.0 m2/g, specific pore volume of 0.1 - 0.25 cm3/g, degreased (for example, annealing for 30 min at 350 - 400oC in a muffle or microwave ovens), the WMD of metal ions 1 - 10%, in the case of the introduction of the activator in the impregnating solution is added ZnNO3c concentration on ion-Zn 1 - 10%. Impregnation occurs by dipping the material into the solution for 1 min Then dried in kilns or on heated drums at temperatures (105 - 120)oC for 30 minutes and Then calcining in a muffle or microwave ovens at a temperature (350 - 400)oC for one hour. After annealing the material must cool down to the temperature of the annealing to room temperature for at least 30 minutes

Examples.

In the prototype were tested the same catalyst and the same reactor. The weight of the loaded catalyst is 1.8 g, hourly rate of the gas mixture and the volume flow of the gas mixture, referred to normal conditions, respectively 53000 h-1and 8900 ml/min Because the hourly rate is the ratio of the reaction space to the volumetric flow rate of the gas mixture, these data will be sufficient for calculation of the reaction space, which amounted to (8900 60)ml/h /53000 h-1= 10.075 ml. Hence calculate the modulus (M) is the mass ratio of the catalyst to the reaction space M = 1.8/10.075 = 0.1787 g/ml [2] studied the oxidation of the gas mixture UB>2- 77.78).% (a stoichiometric excess of oxygen - 1.010). The nitrate concentration of the metal in the impregnating solutions at prigotovleniya the claimed catalysts everywhere was 5% for each salt. In the additional case of the introduction of the activator content ZnNO3in the impregnating solution also was 5%. As the substrate material was chosen fiberglass KS-11-LA, TU-6-11-318-78, capable of a long time to work at 1200oC. All experiments for comparison with the prototype was implemented with the same modulus and the concentrations of the gas mixture in a tubular reactor with a diameter of 3 cm at atmospheric pressure. Since the reaction rate on the claimed catalyst was greater than in the prototype and time consumption 53000 h-1the degree of conversion of the organic component were close to 100%, making it difficult to assess the impact of various parameters on the reaction rate, the hourly rate was not chosen 53000 h-1as in the prototype, and 80000 h-1when this decreases the residence time of the substances in the reactor and therefore decreases the degree of transformation. The degree of conversion was calculated by the formula X = (Cbeg- CKon) 100%/ Cbegwhere Cbegthe concentration of the component at the entrance to the PE low temperature experiments on catalytic oxidation than in the prototype. The temperature of the experiment was chosen such that the degree of conversion of the components were somewhat larger than in the prototype, but less than 100% in order to compare the influence of various parameters on the rate of oxidation. Since the rate of chemical reactions increases dramatically with temperature, the possibility of achieving a given degree of conversion at a lower temperature means a higher rate of catalytic reaction and, consequently, a higher catalytic activity.

Example 1.

The textile material with the above parameters of the optical fiber obtained by the method of the molten molding with a specific surface area of 0.7 m2/g, specific pore volume 0.17 cm3/g was besirevic by annealing for 30 minutes at 350oC in a muffle furnace, and then was impregnated with an aqueous solution of cobalt nitrate concentrations by ion cobalt 5%. Impregnation occurs by dipping the material into the solution for 1 min followed by drying in a drying chamber at a temperature of 110oC for 30 minutes and Then calcining in a muffle furnace at a temperature of 370oC for one hour. After annealing the fabric was cooled from the temperature of annealing before than the prototype (see examples 30, 31). Experiment on catalytic oxidation mixture, the composition and flow rate specified above, was carried out at a temperature of 320oC, if this were achieved, the following degrees of transformation components: CO - 98.50%, CH (all organic ingredients) - 99.90%, NO - 64.20%, which is higher than the cobalt containing catalyst of the prototype (see example 30) and cobalt containing with added platinum catalyst activator prototype (see example 31). Moreover achieved this degree of conversion at a lower temperature (320oC, not 400oC, as in the prototype) this indicates a higher catalytic activity of the claimed invention.

Examples 2 to 5, made in the conditions of example 1 except for adding a salt of another metal in the impregnating solution, demonstrate the influence of various metals (Cu, Ni, Mn, Cr) on the catalytic activity.

Examples 6 to 11 show the influence of the specific surface of fibers on the catalytic activity of Co-Cu-containing catalyst and Co - Cu-containing catalyst with added activator ZnNO3. The textile material with the above parameters of the optical fiber obtained by the method of the molten molding with Ude is of 30 minutes at 350oC in a muffle furnace, and then impregnated with an aqueous solution of cobalt nitrate concentrations by ion cobalt 55. In the case of the introduction of the activator in the flowing solution is added 5% ZnNO3. Impregnation occurs by dipping the material into the solution for 1 min followed by drying in a drying chamber at a temperature of 110oC for 30 minutes and Then calcining in a muffle furnace at a temperature of 370oC for one hour. After annealing the fabric was cooled from the temperature of annealing to room temperature for 30 minutes, the Reduction of the specific surface below 0.2 m2/g does not lead to a further increase of catalytic activity, the increase in specific surface area higher than 5 m2/g results in the decrease of catalytic activity to a level below the prototype due to the increasing interdiffuse resistance. From the results of experiments performed with activator ZnNO3and without him, it follows that the use of the activator allows to reduce the temperature of the experiment, which achieved the degree of conversion components higher than in the prototype to 270oC.

Examples 12 to 17 illustrate the impact of specific fiber volume on the catalytic activity of Co - Cu-containing catalyst and Co-is defined by the parameters of the optical fiber obtained by the method of the molten molding with a specific surface area of 0.7 m2/g and a specific pore volume of 0.1 - 0.25 cm3/g degreased by annealing for 30 minutes at 350oC in a muffle furnace, and then impregnated with an aqueous solution of cobalt nitrate concentrations by ion cobalt 5%. With the introduction of the activator in the flowing solution is added 5% ZnNO3. Impregnation occurs by dipping the material into the solution for 1 min followed by drying in a drying chamber at a temperature of 110oC for 30 minutes and Then calcining in a muffle furnace at a temperature of 370oC for one hour. After annealing the fabric was cooled from the temperature of annealing to room temperature for 30 minutes, the Reduction in the specific volume of pores less than 0.1 cm2/g does not lead to a further increase of catalytic activity, the increase in the specific volume of pores is higher than 0.25 cm2/g results in the decrease of catalytic activity to a level below the prototype due to the increasing interdiffuse resistance. From the results of experiments performed with activator ZnNO3and without him, it follows that the use of the activator allows to reduce the temperature of the experiment, which achieved the degree of conversion components higher than in the prototype to 270oC.

Examples 18 to 23 is displayed on the utilizator with added activator ZnNO3. The textile material with the above parameters of the optical fiber obtained by the method of the molten molding with a specific surface area of 0.7 m2/m, and the specific volume of pores 0.17 cm3/g, besirevic by annealing for 30 minutes at 350oC in a muffle furnace, and then was impregnated with an aqueous solution of cobalt nitrate concentrations by ion cobalt 5%. With the introduction of the activator in the impregnating solution was added 5% ZnNO3. Impregnation occurs by dipping the material into the solution for 1 min followed by drying in a drying chamber at a temperature of 105 - 120oC for 30 minutes and Then calcining in a muffle furnace at a temperature of 370oC for one hour. After annealing the fabric was cooled from the temperature of annealing to room temperature for 30 minutes Reduced drying temperature below 105oC does not lead to a further increase of catalytic activity, increasing the drying temperature is higher than 120oC leads to a decrease in the strength of fixing of the active layer and the decline of catalytic activity to a level below the prototype due to the destruction of the active layer during operation. From the results of experiments performed with activator ZnNO3and without him, it follows that primne components higher than in the prototype to 270oC.

Examples 24 to 29 show the effect of temperature of calcination on the catalytic activity of Co - Cu-containing catalyst and Co - Cu-containing catalyst with added activator ZnNO3. The textile material with the above parameters of the optical fiber obtained by the method of the molten molding with a specific surface area of 0.7 m2/g and a specific pore volume 0.17 cm3/g, degreased with annealing for 30 min at 350oC in a muffle furnace, and then impregnated with an aqueous solution of nitrite cobalt concentrations by ion cobalt 5%. With the introduction of the activator in the impregnating solution is added 5% ZnNO3. Impregnation occurs by dipping the material into the solution for 1 min followed by drying in a drying chamber at a temperature of 110oC for 30 minutes and Then calcining in a muffle furnace at a temperature of 350 - 400oC for one hour. After annealing the fabric was cooled from the temperature of annealing to room temperature for 30 minutes Reduce the temperature of annealing below 105oC and increased above the 120oC leads to a decrease in the strength of fixing of the active layer and the decline of catalytic activity to a level below the nNO3and without him, it follows that the use of the activator allows to reduce the temperature of the experiment, which achieved the degree of conversion components higher than in the prototype to 270oC.

1. A method of manufacturing a textile catalyst on the substrate of the optical fibers, which consists in impregnating the substrate with a solution of salts of metals of variable valency or their mixtures with further drying and calcination, wherein as the substrate material used fiberglass with a specific surface area of 0.2 - 5.0 m2/g and a specific pore volume of 0.1 - 0.25 cm3/g, as an impregnating solution using an aqueous solution of salts of metals of variable valency or their mixtures, stage drying is carried out at a temperature of 105 - 120oC, stage calcination is carried out at a temperature of 350 - 400oC.

2. A method of manufacturing a textile catalyst under item 1, wherein in the impregnating solution further introduce the activator ZnNO3.

 

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