A method of manufacturing a catalytic unit to neutralize the harmful gas emissions

 

(57) Abstract:

The invention can be used in engineering in the design of engines for the purpose of protection from the harmful emissions of the air basin, and also in systems of gas purification environmentally harmful industries. The method is based on obtaining a catalytic layer consisting of a modified aluminum oxide on the surface of the carrier, and is characterized by the fact that the catalytic layer is applied by plasma spraying, and as source material used catalytically inactive composition containing a metal powder of aluminum, aluminum hydroxide and easily degradable metal compounds V - VIII group, yttrium and lanthanides. The catalytically active composition based on the amorphous aluminum oxide, aluminum gamma modification of metal oxides V - VIII group, yttrium and lantanoides get directly into the plasma jet at the set temperature and speed settings spraying and given the composition of the plasma gas. The resulting carrier corrugate and form a honeycomb catalytic unit.

The invention relates to the field of catalytic chemistry, and in particular to methods of manufacturing catalytic what those engines.

A known method for the catalytic unit for flue gas cleaning. According to the method for coating using a liquid composition prepared from a powder of activated alumina, cerium, powdery oxide of cerium and zirconium. The composition is applied to the surface of the solid basics of the medium, then applied a catalyst based on a noble metal.

There is also known a method for the catalytic unit for flue gas cleaning. According to the method of preparing a suspension of the powder mixture of vanadium oxide and aluminum oxide. Then, from a powder mixture of vanadium oxide and aluminum oxide. Then dipped into the suspension medium, dried and calcined to form on the support surface of the oxide layer, after which the coated carrier precipitated catalytically active metal

platinum, rhodium and/or palladium.

The closest known methods for the production of catalytic converters to neutralize the harmful gas emissions is the method adopted for the prototype.

According to the specified method on the internal channels of the monolithic carrier by precipitation cause the catalytic composition, the I of cerium at least one representative from the group, consisting of water-soluble aluminum compounds and hydrates of aluminum oxide, annealing the product of impregnation, followed by the application of at least one precious metal from the group consisting of platinum, palladium, rhodium.

The advantages of this method include the fact that he as the ways analogs provides a carrier with a large free surface (>100 m2/g), which provides a high catalytic activity of such blocks.

The disadvantages of this method as a way of analog is that the catalytically active layer is deposited on the carrier surface uneven thickness and chemical composition. In addition, the carrier impregnated by immersion in a suspension or solution, drying, and so once again dive to 20 30 reoperations does-low-tech way, leads to increased labor costs, and thus increase the cost of the method.

A significant drawback of the prototype method is the poor adhesion of the catalytic layer with a metal (or ceramic) base (carrier)

weak adhesive strength, which leads to the delamination of the catalytically active layer during operation of the unit in terms of mechaniczne catalytic unit, providing a high adhesive strength and catalytic activity of the applied layer with a relatively inexpensive production of this unit.

The problem is solved in that in the method of manufacturing a catalytic unit to neutralize the harmful gas emissions form the inner surface of the block, performed in the media, on the inner surface of which is coated with a catalytically active layer comprising the basis of the modified alumina, according to the invention the catalytically active layer is applied by plasma spraying on a metal flat tape, as source material for plasma spraying a mixture of powders in the following ratio of components: aluminum - 3-10% V VIII metal carbonate group, yttrium and lanthanides in the amount of 5 - 7% aluminium hydroxide else and as a plasma-forming gas using air, then form the inner surface of the block in the form of longitudinal channels by corrugating the metal flat tape with a deposited layer and its subsequent collapse.

Plasma deposition of catalytically active layer allows to provide vzaimna aluminum in the plasma jet) in non-equilibrium conditions, thereby increasing the adhesion strength of the resulting layer on the flat tape is uniform in chemical composition and coating thickness. Getting a catalytically active composition based on a thermodynamic non-equilibrium alumina-modification of the catalytically inactive substances directly into the plasma jet can increase the activity of the catalyst layer due to the fact that the active composition is formed in non-equilibrium conditions in the immediate vicinity of the carrier. Unlike traditional technologies for applying the catalytic coating (deposition from suspensions), special requirements for metallic substrates (using high-low-tech and expensive steels), the proposed method can be implemented on virtually any coated metal substrate.

In addition, the proposed method does not require complex operations associated with the introduction of the applied layer of insoluble catalyst components. In this way, these components can be easily introduced in the form of thermally degradable compounds such as carbonates in catalic brazowego gas air) V VIII metal Carbonate groups are decomposed to oxides, show catalytic ability, which is greatly enhanced by the introduction of complex carbonates.

The formation of the structure of the catalytic unit comprising a plurality of longitudinal channels, allows to increase the free surface of the block, which leads to an increase in its catalytic activity. The proposed method allows to corrugate tape coated with a very small radius of curvature, which also allows to increase the catalytic activity, whereas the methods of application of the catalytic layer deposition does not allow to apply the layer without the risk of blockage of the longitudinal channels, if they are small in cross section. Shirring tape coated with a catalytic coating and the formation then of longitudinal channels block by folding allows occlusion of the (pollution) of the longitudinal channels of the products of combustion during operation of the unit (for example, soot particles) to deploy back the entire surface and mechanically remove the contamination, which dramatically increases the service life of the catalytic unit manufactured according to the proposed method. Such a cleaning operation is in principle impossible in cases where the first operation of the manufacturing unit is forms ocrite by impregnation or precipitation.

Thus, the claimed combination of features (a new sequence of operations, the method of applying the coating composition original composition, processing methods of forming the surface, and so on) allows the manufacture of catalytic units with high adhesive strength catalytic layer while providing the most comprehensive chemical processes neutralize harmful gases emissions during operation of the unit. The catalytic coating is uniform in composition and thickness. The method is a technology and inexpensive, since it has high performance and does not require the use of expensive materials.

The proposed method can be implemented as follows.

Plasma spraying was carried out catalytic coating for the manufacture of catalytic converters intended for neutralization of exhaust gases of the vehicle.

The sputtering was carried out in air using air-plasma gas air) plasma torch. As a metal carrier used foil (width 90 mm, thickness 40 μm) of the heat-resistant steel hromoalyuminievoy. Cut the tape with a length of about 5 m was naviwala spiral on what about a speed of 60 rpm, and the moving carriage mounted on it with a plasma torch along the axis of the drum with a speed of 180 mm/min

As source material for sputtering was used following powders: aluminum 8% aluminium hydroxide: gibbsite 33% boehmite 52% carbonate vanadium 2% carbonate chromium 2% Nickel carbonate 1% cobalt carbonate 0.5% cerium carbonate 0.5% lanthanum carbonate 0.5% yttrium carbonate 0,5%

The mode of deposition: voltage 220V, current 160A, the feed rate of plasma gas (air) 3 m/S. Supply of powders was carried out by two dispensers in different zones of the plasma jet.

The resulting catalytic coating thickness of 20 μm the following chemical composition:

aluminium oxide g modification 92%

the sum of the oxides of vanadium, chromium, Nickel, cobalt, cerium, yttrium and lanthanum

about 8%

After deposition, the metal strip with a catalytic coating corrugated bend radius of 1.2 mm, and then folded in such a way that the longitudinal channels formed by drawing on their inner surface of the catalyst layer.

A method of manufacturing a catalytic unit to neutralize the harmful gas emissions, having a honeycomb structure coated on the inner surface of the catalytically active layer on the basis of modified aluminum oxide, comprising formovani the Khabibullina, which is a flat metal strip, put a catalytically active layer by plasma spraying, using as source material for plasma spraying a mixture of powders containing aluminum, V VIII metal carbonate groups, yttrium and lanthanoids, and the aluminum hydroxide in the following ratio, wt.

Aluminum 3 10

The V VIII metal carbonate groups, yttrium and lanthanides 5 7

The aluminum hydroxide To 100

then form a honeycomb structure in the form of longitudinal channels shirring tape coated with a catalytically active layer and the subsequent downsizing.

 

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