RU2362624C1 - Catalytic element - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention is related to catalytic elements of regular structure for different catalytic processes. Catalytic element was described that represents a single block structure made of separate components - catalytic rods that are distanced from each other by spacer device. Catalytic rods may have different shape of section and diametres, and may also represent different catalysts. Rods in single block structure may create layers installed parallel, perpendicular or at the angle to each other and flow of reagents.

EFFECT: provision of manufacturability of making, low resistance to flow, good missing and turbulisation of reagents flow, high mass- and heat-exchange properties, without disadvantages inherent in these types of catalysts.

6 cl, 6 dwg

Description

The invention relates to catalytic elements of regular structure, which may find application in various catalytic processes.

The most common and simplest type of catalysts to manufacture is catalysts made in the form of various granules. Granular catalysts can be prepared both by extrusion and other methods, for example by compression or pelletizing. All molding methods are highly productive and allow you to get a wide range of formulations and forms of catalysts.

But granular catalysts have their disadvantages during operation:

- high flow resistance; catalyst wear associated with abrasion, which leads to the loss of valuable components, especially for catalysts with precious metals; dust emission; increase in layer resistance; low heat transfer parameters inside the layer. In the apparatus, it is possible to stratify the catalyst layer by the size of the granules, clogging the apparatus with dust from abrasion of the catalyst.

Partially, the disadvantages of granular catalysts are eliminated by another type of catalyst, namely cell blocks.

The use of cell blocks provides low flow resistance.

Cellular units are technologically advanced in operation, have minimal abrasion and abrasion compared to granules, and are quite stable in operation due to the absence of wear associated with friction and vibration.

However, cell blocks have significant disadvantages. These are the disadvantages associated with both the manufacture and operation of the blocks.

When forming blocks, complex and expensive equipment is used, molding performance is low, molding of honeycomb structures is possible for a limited number of ceramic compositions, most formulations either do not give high-quality channels, or crack during drying and heat treatment. A block cannot be made from the most common carrier - gamma-alumina, most often the block monolith and the active layer are two different materials, which creates complexity in the manufacturing process of the block catalyst and often peeling the active layer during operation.

Honeycomb blocks are very sensitive to thermal shock - temperature drops during operation, they have low thermal stability, i.e. cracking at high and variable temperatures, poor heat transfer of ceramics and the possibility of heat dissipation of the reaction in the stream inside the channel.

The presence of channels of small diameter with a long length can give a sharp increase in resistance due to the possible clogging of the channels with reagents or reaction products, or soot.

There is a strong difference in the structure of the flow along the channel in the wall layer of the flow, which imposes additional diffusion restrictions on the process.

Cellular catalytic elements are known (RF 2128081, B01J 35/04, 1999; JP 62-191048, B01J 35/04, 1987; DE 3430886, B01J 35/04, 1986; JP 53-137866, B01D 53/34, 1978. JP 54-141382, B01J 1/00, 1979; EP 0260704, B01J 21/04, 1988, etc.).

In the patent of the Russian Federation 2209117, B01J 35/04, 07/27/2003 a catalytic element of a regular honeycomb structure is described, which is made in the form of a layer of separate prisms connected by side faces and having honeycomb channels, individual prisms having a gap between the side prisms faces 0.1-1.0 diameter of the honeycomb channel. For laying along the perimeter of the layer, triangular and trapezoidal blocks truncated to the diameter of the contact apparatus are used. These catalysts are used when carrying out high-temperature processes in the gas phase, for example, the oxidation of ammonia. Cellular catalysts for the production of sulfuric acid, a process for the oxidation of sulfur dioxide, are proposed. Block cellular catalysts are most widely used in the processes of gas purification from harmful impurities. In all of the above processes, cellular block catalysts exhibit their positive qualities, while retaining the disadvantages, primarily low thermal stability - cracking, peeling of the active catalytic layer from the block monolith, clogging of channels.

This invention solves the problem of developing such a design of the catalytic element, which would allow to combine the advantages of granular and honeycomb catalysts without reproducing their main disadvantages.

To solve this problem, the following design of the catalytic element is proposed.

The catalytic element is a cassette (assembly) in which the individual catalytic elements obtained by standard granulation methods are combined in a common block design.

The catalytic elements are rods or pellets of a catalyst of circular or other cross-section and are assembled using a spacer device in a single unit.

The spacer device can be made in the form of a grid in which the catalyst block is assembled, in the form of pins on which the catalytic elements are fixed, or in the form of plates in which the catalytic elements can be mechanically fixed.

The catalytic element can be formed from parallel or angled layers of catalyst rods, the same is possible when loading the blocks into the reactor. The catalytic elements in the reactor will be oriented in the direction “flow along”, “flow perpendicularly”, “flow at an angle” to the rods, while the degree of turbulization of the flow will vary significantly.

The element can be formed from heterogeneous catalyst rods, that is, from various catalysts having the same shape.

The element may be formed from catalyst rods of different diameters.

The geometry of the rod itself can be not only round, but also different in cross section, which makes it possible to increase the geometric surface.

Advantages of the proposed item.

1. Simple and productive, like extrudate molding.

2. The possibility of forming catalytic rods from a wide range of ceramic compositions, including from active aluminum oxides.

3. Low flow resistance.

4. Constant "frontal run-in" of the flow on the catalytic element.

5. The stream is not closed in the channel, as in a cell unit.

6. Constant changes in the direction and mixing of the flow through the layers of the element.

7. Good mixing and turbulization of the flow of reagents from layer to layer.

8. High mass and heat transfer characteristics.

9. Lack of contact between the rods and, as a consequence, wear by friction.

10. No dust during operation of the catalyst layer.

11. Heat resistance. The absence of thermal expansion-contraction, since the catalytic element is thermally compensated by the structure itself and is not a monolith. No cracking occurs.

12. There is no danger of "clogging" of the catalyst layer with dust, reagents, soot.

The invention is illustrated by the following drawings.

Figure 1 schematically shows a General view of the catalytic element.

Figure 2 shows a diagram of the device of the catalytic element.

Figure 3 shows the movement of the flow of reagents through the catalytic element.

Figure 4 schematically shows a catalytic element with a perpendicular arrangement of the rods.

Figure 5 schematically shows a variant of the rods with different sections.

Figure 6 schematically shows the rods mounted in the remote-control device-grid.

In accordance with this application, experimental catalytic elements of two types were manufactured:

1. Based on gamma alumina catalyst rods coated with platinum. The rods are assembled into a single catalytic unit by a mesh spacer device. These catalytic elements have shown good performance in a hydrogen bonding system in an industrial battery charging section. Catalytic elements operate in convective (without ventilation) air movement through the catalyst.

2. On the core of the rings of high temperature alumina coated with palladium. The granules are combined into a single catalytic element using a spacer in the form of rods. These catalytic elements are tested at an electric locomotive plant in a generator-battery system. The movement of air through the catalyst is forced.

Claims (7)

1. The catalytic element of a regular structure, characterized in that it is a single block design consisting of individual catalytic components combined by a spacer device. 2. The catalytic element according to claim 1, characterized in that the individual components are made in the form of catalytic rods of regular shape. 3. The catalytic element according to claim 1, characterized in that the cross section of the catalytic component of the rod can be any figure. 4. The catalytic element according to claim 1, characterized in that it can consist of catalytic rod components having different diameters. 5. The catalytic element according to claim 1, characterized in that it can consist of catalytic rods, which are different in composition and concentration of active components of the catalysts. 6. The catalytic element according to claim 1, characterized in that the rods are combined in layers located parallel, perpendicular or at different angles, with respect to each other and to the flow of reagents, of the catalytic process. 7. The catalytic element according to claim 1, characterized in that the spacer device is a metal frame (mesh, pins, plates) in which the individual catalytic components are fixed rods.

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