RU2084282C1 - Method of preparing catalyst for cleaning effluent gas - Google Patents

Abstract

FIELD: gas purification. SUBSTANCE: invention relates to gas treatment to remove injurious organic impurities and carbon monoxide and is aimed at providing inexpensive environmentally appropriate method of preparing high-activity gas-treatment catalyst possessing acceptable mechanical strength. Provided method is based on interaction of active components and binders, whereas desired result is achieved by that aforesaid interaction is effected by way of mixing iron- manganese concretions as active components and aluminium hydroxide with pseudoboehmite structure as binder, the ratio of the two components ranging from 1.5:1 to 10:1. Components are mixed advantageously in 6-12% solution of catalytically neutral acid at acid to dry mixture weight ratio (1.5-4):100. EFFECT: reduced cost of gas treatment.

Description

 The invention relates to a method for producing a catalyst for purification of exhaust gas from harmful organic impurities and carbon monoxide.

 One of the promising gas purification methods is the adsorption-catalytic method, which uses adsorbent-catalysts based on drive materials of pyrolusite ores (1). The main disadvantage of such catalysts is the inconstancy of the composition and low mechanical strength.

 A known method of producing a catalyst, which is used in deep oxidation processes when cleaning from harmful organic impurities and carbon monoxide, is the method of impregnating the carrier with a solution of salts of transition elements. So, to obtain a catalyst containing 26 wt. copper oxide supported by active alumina, the carrier is impregnated with a saturated solution of copper nitrate (2). The main disadvantage of this method is the large amount of nitrogen oxides released at the stage of calcination of the catalyst.

 There is a more environmentally friendly method for producing catalysts based on the interaction of active components, which use transition metal cations and binders, selected as a prototype (3). So, in this method, the carrier (binder) alumina of various modifications is impregnated with a solution of an ammonia complex of copper carbonate (active component).

 This method also has several disadvantages, the main of which is the use of expensive synthetic components to obtain a catalyst.

 The required technical result is to create a cheap environmentally friendly method for producing a highly active gas purification catalyst with sufficient mechanical strength.

 In the proposed method for producing a catalyst for purification of exhaust gas from organic impurities and carbon monoxide, based on the interaction of active components and an aluminum oxide binder, the required technical result is achieved by using ground ferromanganese nodules as active components, pseudo bit structure as an aluminum hydroxide binder, and interaction carried out by mixing with a mass ratio of nodules to aluminum hydroxide equal to 1.5: 1 10: 1. Moreover, the mixture s components 6 serves to produce 12% solution of a catalytically neutral acid at a weight ratio of acid to the dry mixture 2.5: 100 4: 100.

 Consider specific specific examples of the preparation of the catalyst.

 Example 1. 60 g of Powdered K-1 nodule and 6 g of binding PHA (ratio of LMC: PHA 10: 1) are filled with 8% acetic acid in an amount of 22 ml (ratio of acid to dry mixture 2.5: 100). The resulting mixture was stirred, molded in the form of cylinders and rings, dried and calcined as in the following examples.

The activity of the catalyst obtained in this way was 8.1 to 8.5 in the oxidation of butane. Specific surface area 132 m ² / g, end strength 2 MPA. The mass is still sufficiently plastic to form catalyst granules in the form of cylinders and rings. With an increase in the ratio of LMC: PHA of more than 10: 1, the rheological properties of the molding material sharply decrease and the catalyst loses its practical value.

Example 2. 30 g of the Product powder TXA is peptized with 10 ml of acetic acid (11%). Then, 45 g of K2 nodule powder and 15 ml of the same acid are introduced (i.e., the ratio of LMC: HA is 1.5: 1, and the acid to mixture is 3.5: 100). The activity of the catalyst was 8.0 8.3. The specific surface was 173 m ² / g, and the strength was 3-4 MPa. With a decrease in the ratio of LMC: GA less than 1.5: 1, the catalytic activity of the catalyst decreases.

 Example 3. 15 g of the Product powder TXA is peptized with 10 ml of acetic acid (8%). Then add 60 g of K-4 nodule powder and 35 ml of the same acid (Ratio of LMC: PHA 4: 1, and the acid and mixture 4: 100). Activity was 8.0 8.3, specific surface 115 m / g, strength 2 MPa.

 The amount of acid (for example, acetic acid) was selected at the rate of 1 mol per 1 mol of aluminum oxide contained in the binder. Shown in the claims, the range of ratios of acid to mixture was determined by the type of binder, the ratio of LMC: PHA, type of nodule. The acid concentration range was determined by the requirement to obtain the necessary rheological properties of the mixture for the formation of the catalyst and its strength.

 An increase in acidity (the use of nitric or even stronger peptizing agent in place of acetic acid) leads to a slight increase in the strength of the granules, but it is inconsistent both from an economic and environmental point of view.

The reaction rate of the catalytic oxidation of butane by atmospheric oxygen was determined in a flow-through installation with a gas mixture flow rate of 10 l / h and a stationary butane concentration of 0.2%. The activity was characterized by the conversion rate of butane at a certain temperature: W • 10 ² ml C ₃ H ₈ / gs .

 In the testing process, nodules of the World Ocean were used (K-1 type A Pacific Ocean, K-2 type A Indian, K-3 type A crust Pacific, K-4 type B Pacific, K-5 Baltic Sea, K-6 type From the Pacific Ocean).

 A method of producing a catalyst consists in mixing ground nodules and a binder in certain proportions in the presence of a catalytically neutral acid, which is proposed (as optimal options) diluted acetic or nitric acid as a peptizing agent. Catalysts based on nodules of these types can be molded in the form of complex geometric shapes, in particular blocks.

 The proposed method allows to make cheaper the use of natural raw materials.

 Ferromanganese nodules contain a number of useful components, including transition metal cations Fe, Mn, Cu, Ni, etc. that are proposed to be used as active components for the preparation of catalysts.

 As a binder, alumina monohydrate AlO (OH), (radiographic pseudoboehmite) is used.

 Aluminum hydroxide of pseudoboehmite structure can be obtained by reprecipitation (PHA product) or by thermochemical activation of technical alumina hydrate (TXA product). In accordance with the results of X-ray and thermogravimetric analyzes of reprecipitation, aluminum hydroxide (PHA) consists only of pseudoboehmite, the product TXA contains 65 wt. h pseudoboehmite, the rest is trihydrates, bayerite and hydrargillite. In this regard, upon receipt of the catalyst, the required amount of PHA as a binder is less than the product of TXA. However, the latter is less scarce and, upon receipt of it, reprecipitation stages are excluded, in which waste water appears that requires special types of treatment. At the same time, it should be borne in mind that excessive dilution of nodules with a binder leads to a decrease in catalytic activity.

 To prepare the catalyst, a mixture of nodule powders and a binder (PHA) is poured into the paddle mixer, acetic or nitric acid is added, and the mass is mixed for 30–40 minutes. When TCA is used as a binder, the latter is peptized in the presence of acid in stage 1 until a plastic mass is formed for 20-30 minutes, then powdery nodules are introduced and stirring is continued for 30 minutes.

 The activity of the nodule-based catalyst in the complete oxidation reactions is determined mainly by the presence of manganese. The most active catalysts prepared using nodules with a high content of manganese. The activity of the catalyst also depends on the amount of binder. A significant increase in the content of PHA and TXA leads to a decrease in activity. However, for some types of nodules, an increase in the percentage of PHA and TXA from 9 to 20 and 33, respectively, does not lead to a decrease in catalytic activity. Apparently, in this case, a significant effect is exerted by a simultaneous increase in the specific surface and porosity.

 Studies have shown that the activity of nodule-based catalysts in the oxidation of carbon monoxide is practically at the level of the prototype, and in the oxidation of butane is much higher. In terms of activity in the oxidation of butane, these catalysts are practically not inferior to the known catalyst based on platinum group metals. At the same time, the sufficient cheapness of raw materials makes their use in the future highly profitable.

 It is extremely important that nodule-based catalysts can be formed into blocks.

 Catalysts in the form of block structures are much more convenient in operation, have low aerodynamic drag, which is especially important when cleaning emissions of large volumes. Block catalysts can be used to clean dust emissions. The scope of the catalysts based on ferromanganese nodules can be very wide. The high specific surface area of the catalysts and their high activity in the low-temperature region make them promising for adsorption-catalytic treatment apparatus for vent exhausts of paint and varnish, furniture and other industries where the main toxic components are alcohols, phenols, and esters are contained at low concentrations.

 It should be noted that nodule-based catalysts have a rather high moisture capacity of 0.5 ml / kg. This makes it possible to easily introduce additional active components by impregnation, significantly expanding the scope of the catalysts.

 The properties of the catalysts obtained using different types of nodules and at different ratios of nodules: a binder were investigated.

 The range of the ratio of LMC and binder was tested experimentally. With an increase in the ratio of LMC: GA more than 10: 1, the rheological properties of the catalyst sharply decrease and it loses its practical value.

 With a decrease in the ratio of less than 1.5: 1, the rheological properties practically do not change, and the catalytic activity decreases sharply.

 With a decrease in the ratio of acid to mixture of 2.5: 100, qualitative mixing of the components is not ensured, and an increase of more than 4: 100 does not lead to an improvement in the properties of the mixture.

 With a decrease in acid concentration below 6% and an increase above 12%, the required humidity of the mixture is not ensured for subsequent technological operations (mixing, molding, drying) and sufficient strength after calcination.

Claims (2)

 1. A method of producing a catalyst for purification of exhaust gas from organic impurities and carbon monoxide by reacting active components and an aluminum oxide binder, characterized in that crushed ferromanganese nodules are used as active components, pseudoboehmite structures are used as aluminum hydroxide binder and the interaction is carried out by mixing them the mass ratio of nodules to aluminum hydroxide equal to 1.5 1 10 1.  2. The method according to p. 1, characterized in that the mixing of the components is carried out in 6 to 12% solution of catalytically neutral acid with a mass ratio of acids and dry mix equal to 2.5 100 4 1000.