RU2298435C1 - Catalyst carrier (options) - Google Patents

Abstract

FIELD: catalyst carriers.

SUBSTANCE: invention relates to structure and composition of carrier based on grid-structured tissue of glass, silica, or another interaction fiber treated with formulations imparting rigidity to grids and preventing deformation-caused destruction of fibers, which carrier is used mainly to retain photocatalytically active material on its surface, but also suitable to retain catalysts exhibiting activity in the absence of light. Provided is catalyst carrier constituted by one or several arranged in parallel layers of corrugated grid made from inorganic woven fibers and impregnated with binding material or constituted by one or several arranged in parallel layers of non-corrugated grid also made from inorganic woven fibers and impregnated with binding material.

EFFECT: increased catalyst retention ability and increased area of illuminated photocatalyst surface.

3 cl, 3 dwg, 8 ex

Description

The invention relates to the design and composition of a carrier based on a mesh fabric of glass, silica or other inorganic fiber treated with compositions that give stiffness to the mesh and prevent the destruction of fibers due to deformation, which is mainly used to hold a photocatalytically active material on its surface, but also suitable for holding catalysts showing activity in the absence of light.

The main parameters of the carriers of photocatalysts and catalysts that determine the activity of the supported or fixed component, as well as the dynamic resistance that the carrier exerts to the flow of a liquid or gaseous reaction mixture, are:

- geometric characteristics determined by the number of tissue layers, their shape and relative position in the carrier layer;

- the porous structure, determined by the number of threads in the warp and weft of the fabric used, as well as the mass content and film thickness of the binder composition, which makes the mesh fabric stiff;

- the chemical composition of the carrier, determined by the chemical composition of the mesh fabric used as the base of the carrier, and the chemical composition of the composition used to impregnate the mesh fabric and bond layers of this fabric to each other.

The development of supports for catalysts and photocatalysts has been the subject of a number of inventions.

Known carrier photocatalyst, consisting of a fiberglass mesh rolled up around a light source (US 5032241, B01J 19/12, 07/16/1991). In this case, the light propagates deep into the grid. The porous structure of the coiled mesh contributes to the ease of passing the reaction mixture through the carrier. The disadvantage of this design is the difficulty of forming a flat or arbitrary shape of the carrier due to the significant flexibility of the fiberglass fabric and the inability to independently keep it attached.

Glass balls are used for sintering photocatalyst carriers, as described in RU 2151632, B01J 21/06, 06/27/2000, and US 6783740, B01J 19/08, 08/31/2004. The developed porous structure of such carriers also allows one to increase the area of the illuminated surface of the photocatalyst. Due to the rather close arrangement of glass balls in carriers of this type, a high resistance to the passing air flow is created. To reduce the resistance to air flow, it is necessary to increase the size of glass balls, which leads to a decrease in the contact time of the reaction mixture and a decrease in the degree of conversion, which, in turn, leads to a decrease in the overall efficiency of the use of such carriers.

A known carrier of a photocatalyst based on plates with ribs arranged in such a way that the contacting edges of parallel adjacent plates are angled to each other (RU 2262455, B60H 3/06, 10/20/05). The reaction mixture enters the gaps between adjacent plates. This design provides easy transmission of the reaction mixture with a low pressure drop. The disadvantages of such a carrier is the poor illumination of the ribbed surface of the carrier due to the fact that light is incident on the surface of the plates at an acute angle through narrow slots formed by the contacting plates. In addition, this design is too cumbersome and cannot be used for cleaning liquid mixtures, since the edges of the contacting plates, located at an angle to each other, will contribute to a high degree of uneven flow of the liquid mixture.

Fiberglass is an excellent carrier for photocatalysts because it is chemically inert and highly flexible.

Closest to this invention are carriers of fiberglass with a random arrangement of individual threads (glass wool). Moreover, it was proposed not to remove the sizing of glass fibers located mainly in the plane of the sheet carrier (US 6239050, B04D 1/00, 05/29/2001).

The invention (US 5766455, C02F 1/32, 06/16/1998) describes a carrier of tightly spaced glass fibers (pressed glass wool); on one, both sides of the support or throughout the thickness, a semiconductor catalyst is applied. The reaction mixture is passed through a carrier. Such a carrier can be corrugated and at the same time serve as a dust filter. The first disadvantage of this invention is the need to create a large overpressure of the reaction mixture in order to ensure its passage through the carrier. The second significant disadvantage of this invention is that due to the high density of the glass fibers, the effective depth of penetration of UV light into the carrier is small. This leads to a decrease in the efficiency of using such a carrier in the photocatalytic processes of water and air purification.

It can be seen from the above examples that, despite the variety of existing designs of photocatalyst carriers, they have significant drawbacks that need to be addressed.

The invention solves the problem of creating an effective carrier, used mainly for holding photocatalytically active material on its surface, but also applicable for holding catalysts that are active in the absence of light.

The first version of the catalyst carrier consists of one or more parallel layers of corrugated mesh made of inorganic woven fibers and impregnated with a binder in an amount of 5-500 wt.% By weight of the non-impregnated mesh.

The mesh size of the inorganic woven fibers is from 0.2 to 10 mm. As an impregnating binder, it contains organic or inorganic adhesives.

The second embodiment of the catalyst carrier consists of one or more parallel layers of non-corrugated mesh alternating with layers of corrugated mesh made of inorganic woven fibers and impregnated with a binder in an amount of 5-500 wt.% Of the weight of the non-impregnated mesh.

The mesh size of the inorganic woven fibers is from 0.2 to 10 mm. As an impregnating binder, it contains organic or inorganic adhesives.

The third version of the catalyst carrier consists of one or more parallel layers of non-corrugated mesh made of inorganic woven fibers and impregnated with a binder in an amount of 5-500 wt. % of the weight of the non-impregnated mesh.

The mesh size of the inorganic woven fibers is from 0.2 to 10 mm. As an impregnating binder, it contains organic or inorganic adhesives.

The carrier proposed in this invention allows you to purge the reaction mixture with a low pressure drop, create a high illuminated surface area of the photocatalysts, has adjustable flexibility and stiffness to create large self-supporting blocks, can serve as an adsorption filter at the same time.

The carrier comprises a network of inorganic fibers, preferably glass, silica or basalt fibers, impregnated with an inorganic or organic binder material. The impregnated mesh can be corrugated to increase the contact area of the carrier with reagents, including light. Corrugated and non-corrugated impregnated mesh can be bonded together with their surfaces or the tops of the ribs using inorganic or organic binder material with the formation of a multilayer structure. In this case, corrugated and non-corrugated impregnated mesh can be alternated to increase the strength of the structure. Single or multilayer structures can be molded to give the desired shape of the carrier - cylindrical, flat, conical, wavy, polygonal, etc. As a bonding material, any binder compositions that, after solidification, form solid materials that are resistant to the action of catalysts and photocatalysts. Inorganic binders that are not oxidized are preferred. Catalysts and photocatalysts can be applied on one or both sides of the carrier or on all sides of the layers of the impregnated mesh. The carrier may be irradiated with light from one or both sides.

Figure 1 schematically shows a section of a multilayer carrier consisting of four layers of a corrugated impregnated mesh of inorganic fibers.

Figure 2 schematically shows a section of a multilayer carrier, consisting of three layers of corrugated impregnated mesh, alternating with three layers of non-corrugated impregnated mesh of inorganic fibers.

Figure 3 schematically shows a section of a multilayer carrier, consisting of six layers of non-corrugated impregnated mesh of inorganic fibers.

In addition to the function of a catalyst or photocatalyst carrier, impregnated nets of inorganic material can serve as adsorbents due to the fact that many materials of inorganic origin used as a binder have a large specific surface area.

The invention is illustrated by the following examples.

Example 1

A mesh of glass fiber with the number of threads in the weft is 40 by 10 cm, the base is 80 by 10 cm and cells 2 × 2 mm in size are impregnated with epoxy glue. The impregnated mesh is molded into corrugations with the shape of an equilateral triangle and a side of 1 cm. Six layers of corrugated impregnated fiberglass mesh are connected to each other by vertices. The mass fraction of epoxy glue is, according to the weight analysis, 23% of the mass of the initial non-impregnated mesh.

Example 2

The glass fiber net with the number of threads in the weft is 22.5 by 10 cm, the basis of 50 threads by 10 cm and a mesh size of 5x5 mm is impregnated with phenol-formaldehyde resin. The impregnated mesh is molded into corrugations with the shape of an equilateral triangle and a side of 2 cm. Three layers of corrugated impregnated fiberglass in the carrier alternate with three layers of non-corrugated impregnated fiberglass. The mass fraction of phenol-formaldehyde resin after solidification is, according to the weight analysis, 31% of the mass of the initial unimpregnated mesh.

Example 3

A mesh of glass fiber with the number of threads in the weft 22 by 10 cm and the number of threads in the warp 26 threads per 10 cm, forming a cell size of 2 × 2 mm, impregnated with silicate inorganic glue. The impregnated mesh is molded into corrugations having the shape of an isosceles triangle with a rounded apex. The dimensions of the sides of the triangle are 3 cm, the base size of the triangle is 4 cm. Four layers of corrugated impregnated fiberglass mesh are connected to each other by the vertices of the triangles. The mass fraction of silicate glue after hardening is, according to the data of weight analysis, 25% of the mass of the initial unimpregnated mesh.

Example 4

A grid of basalt fiber with the number of threads in the weft 25 by 10 cm and the number of threads in the warp 30 by 10 cm, forming cells 3 × 3 mm in size, is impregnated with aluminophosphate inorganic glue. The impregnated mesh is molded into sinusoidal corrugations with a period of 30 mm and a height of 10 mm. Two layers of molded corrugated mesh alternate with two layers of non-corrugated impregnated mesh. The mass fraction of aluminophosphate glue after hardening is, according to the weight analysis, 58% of the mass of the initial unimpregnated mesh.

Example 5

The glass fiber mesh with the number of threads in the weft 22 by 10 cm and the number of threads in the warp 26 by 10 cm is impregnated with epoxy. The impregnated mesh is molded into corrugations in the form of an equilateral triangle with a side of 1 cm. The carrier contains a layer of impregnated corrugated fiberglass mesh and a layer of impregnated non-corrugated fiberglass mesh. The layers are bonded with epoxy glue. The mass fraction of epoxy glue is, according to the weight analysis, 21% of the mass of the initial non-impregnated mesh.

A photocatalyst, titanium dioxide, is deposited on the surface of the carrier. A portion of 3 × 3 cm ^{2 was} cut from the carrier with the catalyst. For comparison, a flat glass plate of 3 × 3 cm ² with a photocatalyst deposited on one side — titanium dioxide — was taken. The carriers were tested in the oxidation of acetone vapor in a flow-circulation reactor when the DKS-1000 lamp was irradiated with ultraviolet light. The oxidation rate of acetone on a glass plate was 9 × 10 ⁻⁹ mol / s. The oxidation rate of acetone on the support was 1.2 × 10 ⁻⁸ mol / s. Thus, the support allows to achieve a higher oxidation rate and at the same time provides easy passage of the reaction mixture and good contact with the catalyst.

Example 6

A silica fiber net with the number of threads in the weft 22 by 10 cm and the number of threads in the warp 26 by 10 cm is impregnated with an aluminophosphate inorganic binder. The impregnated mesh is molded into corrugations in the shape of an equilateral triangle with a side of 1 cm. Two layers of the molded impregnated mesh are connected by vertices. The geometric area of the carrier is 15 × 20 cm ² . The mass fraction of the aluminophosphate binder after solidification is, according to the weight analysis, 96% of the mass of the initial unimpregnated mesh

A catalyst for thermal oxidation of carbon monoxide (CO) Pd / TiO ₂ in an amount of 3 g with a palladium content of 1 wt.% Is fixed on the surface of the support. The carrier with the catalyst is placed in a sealed chamber with a volume of 404 liters. The air in the chamber is heated with a water radiator to a temperature of 60 ° C.

CO is introduced into the chamber with an initial concentration of 1200 ppm and then the concentrations of CO and CO ₂ are recorded. The latter is formed in the chamber as a result of a dark reaction.

The average rate of dark oxidation is 60 ppm.

Example 7

Similar to example 6 with the exception that as the catalyst carrier, an untreated fiberglass mesh with a geometric surface equal to the mesh surface used in example 6 for the manufacture of the carrier is used. The grid is evenly stretched on the frame. The average rate of dark oxidation of CO was 25 ppm.

A comparison of examples 6 and 7 shows that the impregnation of the mesh with a binder composition provides 2.4 times higher catalyst activity due to a more uniform deposition of the catalyst. In addition, the geometric dimensions of the media described in example 6 are several times smaller than the dimensions of the media described in example 7.

Example 8

The glass fiber mesh with the number of threads in the weft 22 by 10 cm and the number of threads in the warp 26 by 10 cm is impregnated with epoxy. Ten layers of impregnated non-corrugated mesh are arranged in parallel and glued together at the contact points of the filaments of adjacent grids. The mass fraction of epoxy resin is, according to the weight analysis, 31% of the mass of the initial unimpregnated mesh.

The carrier proposed in this invention allows you to purge the reaction mixture with a low pressure drop, create a high illuminated surface area of the photocatalysts, has adjustable flexibility and stiffness to create large self-supporting blocks, can serve as an adsorption filter at the same time.

Claims (3)

1. A catalyst carrier based on an inorganic fiber, characterized in that it consists of one or more parallel layers of corrugated mesh made of inorganic woven fibers, impregnated with a binder based on organic or inorganic adhesives, in an amount of 5-500 wt.% From the weight of the non-impregnated mesh and with mesh size from 0.2 to 10 mm. 2. A catalyst carrier based on inorganic fiber, characterized in that it consists of one or more parallel layers of non-corrugated mesh, alternating with layers of corrugated mesh made of inorganic woven fibers, impregnated with a binder material based on organic or inorganic adhesives, in an amount of 5 -500 wt.% From the weight of the non-impregnated mesh and with a mesh size of 0.2 to 10 mm. 3. A catalyst carrier based on an inorganic fiber, characterized in that it consists of one or more parallel layers of a non-corrugated mesh made of inorganic woven fibers, impregnated with a binder based on organic or inorganic adhesives, in an amount of 5-500 wt.% From the weight of the non-impregnated mesh and with mesh size from 0.2 to 10 mm.

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