KR101807833B1 - A process for the preparation of ceramic honeycomb catalyst supporter having a low coefficient of expansion and the ceramic honeycomb catalyst supporter prepared therefrom - Google Patents

Abstract

The present invention relates to a process for producing a ceramic honeycomb catalyst support having a low thermal expansion coefficient and a ceramic honeycomb catalyst support produced thereby, which comprises a step of preparing a mixture of a catalyst support component containing cordierite as a main component, a molding step, a heating step Wherein the calcination step is carried out at a calcination temperature of 1408 to 1412 DEG C for 10 to 14 hours or at a calcination temperature of 1413 to 1417 DEG C for 3 to 5 hours, According to the method for producing a ceramic honeycomb catalyst support having a low thermal expansion coefficient of the present invention, the thermal expansion coefficient is low, and even when the exhaust gas at a high temperature is filtered for a long period of time, there is an advantage that mechanical properties such as cracks do not deteriorate. In addition, the ceramic honeycomb catalyst support of the present invention can be usefully used as a catalyst support for automobiles, which has a high content of cordierite, has excellent thermal shock resistance, and is manufactured into a honeycomb structure to effectively reduce air pollution.

Description

Technical Field [0001] The present invention relates to a method for producing a ceramic honeycomb catalyst support having a low thermal expansion coefficient and a ceramic honeycomb catalyst support prepared thereby,

The present invention relates to a process for producing a ceramic honeycomb catalyst support having a low thermal expansion coefficient and a ceramic honeycomb catalyst support prepared thereby, and more particularly, to a ceramic honeycomb catalyst support having a low thermal expansion coefficient by controlling the firing conditions during the production process of the honeycomb catalyst support. To a method for producing a honeycomb catalyst support and to a ceramic honeycomb catalyst support produced thereby.

Diesel cars are competitive in terms of maintenance cost and pollutant reduction compared to automobiles using gasoline because of their excellent fuel combustion efficiency, low maintenance cost and low total emission of pollutants. In recent years, the development of diesel engine manufacturing technology has led to an increase in the number of diesel vehicles worldwide. Despite the steady reduction of pollutant emissions due to the development of engine design and manufacturing technology, there is a lot of research in this field due to the difficulty in satisfying the regulated value because the pollutant regulations are planned to be strengthened in the future.

A variety of system configurations have been attempted to reduce the emissions of diesel vehicles (eg, cyclic thermal incineration, catalyzed filters), but the use of diesel particulate filter (DPF) roneun silicon carbide (SiC) and cordierite _{(cordierite) (2MgO · 2Al 2} O 3 · 5SiO 2) is currently being used.

Silicon carbide (SiC) has the disadvantages of high thermal shock resistance, high thermal conductivity, difficulty in manufacturing and high cost, and cordierite has a low thermal expansion coefficient, excellent thermal shock resistance and low dielectric constant characteristics, ) As a material for bricks, but also for electronic materials, and as a honeycomb structure for reducing air pollution, the catalyst support or itself is used as a diesel particulate filter. In particular, cordierite honeycomb is rapidly gaining importance due to growing interest in environmental pollution and increasing regulations.

Waste gases emitted by internal combustion engines or boilers that use hydrocarbon fuels, such as gasoline or diesel, during chemical processes can cause serious pollution in the atmosphere. The waste gas contains nitrogen oxide, carbon monoxide or various volatile organic substances. Therefore, in order to remove these components, a catalytic converter is attached to the rear end of the waste gas generating region to convert harmful substances into harmless gases.

A cordierite ceramic extrusion molded article having a very small thermal expansion coefficient is used as the catalyst support of such a catalytic converter. In addition, when diesel is used as a fuel, an attempt is made to remove harmful substances using a specific component catalyst while passing particulate matter mainly composed of carbon contained in exhaust gas through a porous filter body. A cordierite ceramic filter is used as a porous filter having thermal expansion coefficient characteristics. Almost all automobiles currently use exhaust gas purifiers made of ceramics. Since the exhaust gas is at a high temperature, it is natural that ceramics capable of withstanding thermal shock are eligible.

On the other hand, the ceramic honeycomb is a catalyst carrier material which can increase the structural strength by increasing the structural strength by increasing the specific surface area, increasing the activity, lowering the pressure loss because of the good permeability, and enhancing the heat insulating effect.

The ceramic honeycomb may have a columnar shape, a columnar shape, a block shape, a plate shape, and an elliptic shape. Examples of the ceramic honeycomb include a cylindrical shape and an elliptical shape for automobile exhaust gas, a block shape or a plate shape for deodorization catalyst, The footprints are often used for dragonflies.

Generally, the application field of ceramic honeycomb is catalyst support for purification of exhaust gas of automobiles, but recently it is spreading to other fields due to strengthening of atmospheric environment regulations. Typical examples are SCR catalyst, which is a key component of Selective Catalytic Reduction (SCR), which harmlessly converts nitrogen oxides generated during combustion of power plants, incinerators and marine engines, various harmful gases And a catalyst for removing various volatile organic compounds (VOC).

The manufacturing process of the ceramic honeycomb is such that the raw materials are crushed and combined, the additives such as the plasticizer are mixed, the honeycomb structure is formed through various molding operations, and the honeycomb is dried and fired to form a strong single body.

In the pressure molding, the plasticity of the raw material powder is not a serious problem, but extrusion molding requires various molding additives such as a binder, a lubricant, a plasticizer and a peptizing agent in order to make a raw material into a mortar (or dough) Most of the molding assistants are organic compounds such as methyl cellulose (MC), polyvinyl acrylate (PVA), carboxyl methyl cellulose (CMC), and polyethylene glycol (PEG) use.

The molded product extruded using the molding aid is subjected to a drying step to remove some of the additives that have been added at the time of molding to maintain strength in a state in which firing is possible. These semi-finished products are cut to fit the application and heat-treated at high temperature to become finished products.

Ceramic honeycomb structure is applied to various fields by making full use of its shape and functional characteristics. Especially, it is mainly used in the field of environmental pollution removal, and it will be widely used if various functional materials are used in the future.

For example, in Korean Patent Laid-Open No. 10-2003-0088047, porous silicon carbide powder is mixed and kneaded, extruded, dried and fired in an argon atmosphere at an atmospheric pressure of 2200 ° C to form a plurality of honeycomb filters made of silicon carbide- , An inorganic binder, an organic binder, and an inorganic particle to form a single ceramic honeycomb unit, thereby reducing the rapid thermal shock resistance generated in the diesel engine, thereby enhancing durability, and further improving the durability of the pure silicon carbide honeycomb filter Thereby improving the thermal conductivity and facilitating regeneration of the filter.

However, in order to fired ceramic honeycomb, a special heat treatment device is required for high-temperature firing such as 2200 ° C. In addition to a high-energy process requiring a great deal of heat energy, And a new step of bonding the respective filters by using the sealing material as an adhesive material to reduce the cost and the productivity, as well as to prevent gas leakage of the sealing material layer So that unnecessary duplication of manufacturing is caused by forming a roughness preventing layer on the outer circumferential surface of the filter, which causes a complex increase in cost. Because the fundamental reason for this is that silicon carbide (SiC) materials are used for thermal conductivity and durability, the thermal expansion coefficient of silicon carbide ceramics is generally not so small as 4.2 × 10 ^-6 K ^-1 , Cracks may occur due to stress or thermal shock, which may cause partial breakage.

Korean Patent Laid-Open Publication No. 10-2008-0060221 discloses a method for producing a honeycomb-type ceramic particle-capturing filter carrier, which comprises the steps of: preparing silicon carbide 1, clay 0.05-0.5, face powder 0.1-0.35, engine oil 0.025-0.05, water 0.2-0.35 The paste is extruded together with a dye to form a honeycomb carrier having a cell density of 4 to 62 cells / cm < 2 >, and then dried at a room temperature, and the cell is alternately sealed at the end face of the honeycomb carrier A sintered honeycomb-type particle-collecting filter carrier was prepared by holding the green ceramic wall-flow particle-collecting filter carrier at a temperature of 1250 to 1350 ° C for 0.5 to 12 hours, and this was mixed with silicon carbide 1, clay 0.2 to 1 And a water glass of 0.06 to 0.35 with a plurality of the filtration carriers described above, and a manufacturing method of the honeycomb type ceramic particle capture filtration carrier. It can be considered that the difficulty of sintering at high temperature was solved by lowering the sintering temperature of silicon carbide of 2200 ° C. or higher to 1250 to 1350 ° C. by using clay as the solvent for silicon carbide settlement. However, 1250 to 1350 ° C. means that the sintering temperature The thermal expansion coefficient of the honeycomb ceramic particle collecting filter carrier made of the patent also has to be similar to that of the clay. Therefore, the temperature of the exhaust gas, in which the engine temperature rapidly changes from a low temperature to a high temperature, is repeated There is a possibility that the durability of the honeycomb-type ceramic particle-trapping filter carrier can not be guaranteed for a long period of time.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method for manufacturing a ceramic honeycomb catalyst support for automobiles, which has a low thermal expansion coefficient and does not deteriorate mechanical properties such as cracks even when a high temperature exhaust gas is filtered for a long period of time .

Another object of the present invention is to provide a ceramic honeycomb catalyst support for automobile manufactured according to the above-described method.

In order to solve the above-mentioned technical problems, the present invention provides a method of manufacturing a ceramic honeycomb support comprising a step of preparing a mixture for mixing a catalyst support component containing cordierite as a main component, a molding step, a heating step and a firing step,

Wherein the calcining step is carried out at a calcination temperature of 1408 to 1412 占 폚 for 10 to 14 hours or at a calcination temperature of 1413 to 1417 占 폚 for 3 to 5 hours. .

According to one specific embodiment of the present invention, graphite, a binder, polyvinyl alcohol, triethylene glycol and a lubricating oil can be mixed with cordierite as a main component in the step of preparing the mixture. Specifically, 1 to 2 parts by weight of graphite, 4 to 6 parts by weight of a binder, 1 to 2 parts by weight of polyvinyl alcohol, 0.1 to 1 part by weight of triethylene glycol and 0.1 to 1 part by weight of a lubricating oil are added to 100 parts by weight of cordierite Are mixed with each other.

The cordierite is used as a main material of the ceramic honeycomb catalyst support according to the present invention, and the ceramic honeycomb catalyst support made of cordierite has a diameter of 5 to 50 μm in the pores existing therein.

According to one specific embodiment of the present invention, in the heating step, the rate of temperature rise is controlled at 0.87 to 3 ° C / min to form fine pores produced by the raw materials mixed in the preparation of the mixture and pore- The macropores can be made uniform.

At this time, the binder component may be selected from the group consisting of water, alcohol, acrylic, and methyl cellulose, and most preferably, it is composed of methyl cellulose.

The shaping step is a step of shaping the mixed mixture through the mixture preparing step. The mixed mixture is formed into a honeycomb structure through the mixture preparing step. At this time, the cross-section of the through hole formed in the honeycomb- May be triangular, square, hexagonal, circular, and the like.

The process of forming the mixed mixture into the honeycomb structure through the mixture preparation step in the forming step may be a known molding method and a molding apparatus, It is preferable that the inner wall thickness of the molded article having the shape is formed so as to have 100 to 400 mm most suitable for purifying the catalyst support.

The heating step is a step of heating the molded product manufactured through the molding step and heating the molded product manufactured through the molding step to a sintering temperature at a heating rate of 0.87 to 3 ° C / min. The macropores formed on the surface of the molded product are fine and uniformized into pores having a certain range of diameters.

The heating step preferably comprises one furnace selected from the group consisting of an electric furnace, a brick furnace and a gas furnace, and most preferably a furnace with a temperature rise temperature of 0.87 캜 / min.

The firing step is a step of firing a molded product that has undergone the heating step, and the molded product having been subjected to the heating step is fired under the following two conditions:

(1) baking is performed at a temperature of 1408 to 1412 deg. C, preferably 1410 deg. C, for 10 to 14 hours, preferably 11 to 13 hours, more preferably 11.5 to 12.5 hours; or

(2) baking is carried out at 1413 to 1417 deg. C, preferably at 1415 deg. C for 3 to 5 hours, preferably 3.5 to 4.5 hours.

The object of the present invention can be sufficiently attained only at the firing temperature and time as described above. Otherwise, when the thermal expansion coefficient of the ceramic honeycomb catalyst support for automobile is increased compared with the thermal expansion coefficient at the firing temperature and time, Resulting in deterioration of mechanical properties.

Particularly, in the case of a compact furnace in which the temperature control of the furnace is precisely performed, it is preferable that the firing step is performed at the firing temperature and the condition (2). However, in a large furnace in which the control of the furnace internal temperature is difficult to precisely, Temperature control and the like are taken into account, it is preferable that the firing is performed at the firing temperature and the condition (1).

In the meantime, the present invention provides a ceramic honeycomb catalyst support having a low thermal expansion coefficient according to the manufacturing method.

As described above, according to the method for producing a ceramic honeycomb catalyst support according to the present invention, the thermal expansion coefficient is low, and even when the exhaust gas at a high temperature is filtered for a long period of time, there is an advantage that mechanical properties such as cracks do not deteriorate. In addition, the ceramic honeycomb catalyst support of the present invention can be usefully used as a catalyst support for automobiles, which has a high content of cordierite, has excellent thermal shock resistance, and is manufactured into a honeycomb structure to effectively reduce air pollution.

1 is a graph showing a change in thermal expansion coefficient depending on a firing temperature in a firing step in the production of a ceramic honeycomb catalyst support.
FIGS. 2 and 3 are graphs showing changes in the thermal expansion coefficient depending on the holding time in the firing step in the production of the ceramic honeycomb catalyst support.

Hereinafter, embodiments of the present invention will be described in detail to facilitate understanding of the present invention. However, the embodiments according to the present invention can be modified into various other forms, and the scope of the present invention should not be construed as being limited to the following embodiments. Embodiments of the invention are provided to more fully describe the present invention to those skilled in the art.

≪ Example 1 >

100 parts by weight of cordierite, 1.5 parts by weight of graphite, 5 parts by weight of methylcellulose, 1.5 parts by weight of polyvinyl alcohol, 0.6 part by weight of triethylene glycol and 0.6 part by weight of lubricating oil were mixed to prepare a mixture, , And the shaped product molded with the honeycomb structure was charged into an electric furnace and heated to a specified firing temperature at a heating rate of 3 DEG C / min and then heated at a specific firing temperature (1410 DEG C, 1415 DEG C, 1420 DEG C, and 1425 DEG C) 4 hours, 8 hours, 12 hours and 16 hours to prepare a ceramic honeycomb catalyst support.

Test Example 1 Measurement of thermal expansion coefficient according to sintering time

The thermal expansion coefficient of the ceramic honeycomb catalyst support prepared in Example 1 according to the firing time was measured and shown in Table 1 and FIG. The firing holding time was 4 hours and the firing temperature was 1410 ° C, 1415 ° C, 1420 ° C and 1425 ° C, respectively, and the porosity, water absorption and thermal expansion coefficient were measured and shown in Table 1 and FIG. 1 is a graph showing a change in thermal expansion coefficient depending on a firing temperature in a firing step in the production of a ceramic honeycomb catalyst support.

Firing temperature (캜) 1410 1415 1420 1425 Porosity (%) 39.11 39.45 39.87 39.25 Water Absorption (%) 25.27 25.56 26.09 25.46 CTE (* 10 ^-6 / ° C) 0.676 0.596 0.806 0.765

As shown in Table 1 and FIG. 1, there was no significant difference in the porosity and water absorption according to the firing temperature change, and the thermal expansion coefficient showed the lowest value at the firing temperature of 1415 ° C.

≪ Test Example 2 > Measurement of thermal expansion coefficient according to holding time of firing process

The thermal expansion coefficient of the ceramic honeycomb catalyst support prepared in Example 1 according to the firing holding time was measured.

The porosity, water absorption, and thermal expansion coefficient were measured at a firing temperature of 1410 캜 and a holding time of 4 hours, 8 hours, 12 hours, and 16 hours, respectively, and the results are shown in Table 2 and FIG. FIG. 2 is a graph showing a change in thermal expansion coefficient according to a holding time in a firing step in the production of a ceramic honeycomb catalyst support.

Firing time (hours) 4 8 12 16 Porosity (%) 39.11 39.31 41.70 41.39 Water Absorption (%) 25.27 25.39 27.97 27.69 CTE (* 10 ^-6 / ° C) 0.676 0.717 0.491 0.690

As shown in Table 2 and FIG. 2, there was no significant difference in the porosity and moisture absorption according to the change of the firing holding time, and the thermal expansion coefficient was the lowest value at the firing holding time of 12 hours .

≪ Test Example 3 > Measurement of thermal expansion coefficient according to holding time of firing process

The thermal expansion coefficient of the ceramic honeycomb catalyst support prepared in Example 1 according to the firing holding time was measured.

The porosity, water absorption, and thermal expansion coefficient were measured at a firing temperature of 1415 ° C and a holding time of 4 hours, 8 hours, 12 hours, and 16 hours, respectively, and the results are shown in Table 3 and FIG. 3 is a graph showing a change in thermal expansion coefficient depending on a holding time in a firing step in the production of a ceramic honeycomb catalyst support.

Firing time (hours) 4 8 12 16 Porosity (%) 39.45 39.66 39.87 40.53 Water Absorption (%) 25.56 25.70 26.05 26.71 CTE (* 10 ^-6 / ° C) 0.595 1.063 0.932 0.728

As shown in Table 3 and FIG. 3, there was no significant difference in the porosity and moisture absorption according to the change of the firing holding time, and the thermal expansion coefficient showed the lowest value when the firing holding time was 4 hours .

≪ Test Example 4 > Crystalline phase analysis according to firing temperature and holding time

The crystallization of the ceramic honeycomb catalyst support prepared in Example 1 according to the calcination temperature and the retention time was analyzed and is shown in Table 4 below.

Firing condition Indi / cord ratio CTE 4 hours at 1410 ° C 32.3 / 67.7 0.676 4 hours at 1415 ° C 30.6 / 69.4 0.596 4 hours at 1420 ° C 34.4 / 65.6 0.806 1410 ° C for 12 hours 24.6 / 75.4 0.491 16 hours at 1410 ° C 23.2 / 76.8 0.69

As shown in Table 4, as the temperature was increased up to 1415 ° C., the content of α-cordierite (Indiacite) decreased and the content of cordierite decreased, but at a temperature of 1420 ° C. Different results were obtained. In addition, it was confirmed that when the firing time is increased, the α-cordierite increases and the cordierite ratio increases. As a result, there is a ratio of α-cordierite to cordierite which exhibits an optimum coefficient of thermal expansion, and this value is confirmed to be 75:25 in α-cordierite: cordierite.

As described above, according to the method for producing a ceramic honeycomb catalyst support according to the present invention, the thermal expansion coefficient is low, and even when the exhaust gas at a high temperature is filtered for a long period of time, there is an advantage that mechanical properties such as cracks do not deteriorate. In addition, the ceramic honeycomb catalyst support of the present invention can be usefully used as a catalyst support for automobiles, which has a high content of cordierite, has excellent thermal shock resistance, and is manufactured into a honeycomb structure to effectively reduce air pollution.

Claims (4)

A method for producing a ceramic honeycomb support comprising a mixture preparation step for mixing a catalyst support component, a shaping step, a heating step and a calcination step,
The catalyst support component is composed of 1 to 2 parts by weight of graphite, 4 to 6 parts by weight of a binder, 1 to 2 parts by weight of polyvinyl alcohol, 0.1 to 1 part by weight of triethylene glycol and 0.1 to 1 part by weight of lubricating oil per 100 parts by weight of cordierite By weight,
Wherein the calcining step is performed at a calcination temperature of 1413 to 1417 캜 for 3 to 5 hours. delete The method according to claim 1,
Wherein the forming step comprises shaping the mixed mixture through the mixture preparing step into a honeycomb structure. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Wherein the heating step is performed by heating the shaped material produced through the forming step to the firing temperature at a heating rate of 0.87 to 3 占 폚 / min.

Images