JP2005081313A - Production method for monolith type catalyst, and drying apparatus used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To positively make coating amount different in a radial direction, while suppressing dispersion of coating amounts of catalyst slurry of individual carriers of a monolith type catalyst. <P>SOLUTION: Natural moisture absorbed in a carrier 1 from the atmosphere is removed in advance by applying forced drying treatment by using a hot air supplying device 4, then the carrier is subjected to humidifying treatment as a pretreatment before coating the catalyst slurry. The carrier 1 subjected to the drying treatment in advance has smaller dispersion of the coating amounts of the catalyst slurry of the individual carriers 1 compared to those not subjected to the drying treatment, at the same time, the coating amount increases. By installing a shielding plate 42 with a ventilation hole 43 formed thereon between the carrier 1 and the hot air supplying device 4, drying degree of the carrier 1 in the radial direction is positively made different, and the coating amount of the catalyst slurry is correspondingly varied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a monolith type catalyst (hereinafter referred to as catalyst) and an apparatus used therefor, and in particular, in producing a catalyst for use in an exhaust gas purification system of an automobile or the like, a monolith type carrier having a hygroscopic property ( The present invention relates to a manufacturing method suitable for coating a catalyst slurry in which, for example, alumina or ceria as a main component and platinum or palladium is mixed, and a drying apparatus used therefor.

As a production method suitable for coating a catalyst slurry on a carrier, the one described in Patent Document 1 has been proposed. In the manufacturing method described in Patent Document 1, humidification is performed prior to coating a highly viscous catalyst slurry on a honeycomb-shaped ceramic carrier having a large number of cells. By humidifying the carrier, the medium (for example, moisture) contained in the catalyst slurry is prevented from being absorbed by the cell wall surface, and the cell is coated with the catalyst slurry without causing clogging due to an increase in the viscosity of the catalyst slurry. It becomes possible. In addition to the method for producing the exhaust gas purifying catalyst described in Patent Document 1, the same type is described in, for example, JP-A-1-307455.
Japanese Patent No. 2616157

  However, according to the catalyst production method disclosed in Patent Document 1, there is a possibility that variations in the coating amount of the catalyst slurry may occur on individual carriers. For example, in the case of a hygroscopic carrier such as ceramic, even if it is covered with a cardboard box or a vinyl cover in the storage or distribution process before the catalyst slurry is coated, changes in storage time and weather conditions (especially changes in humidity) Therefore, variation may occur in the natural moisture absorption amount of each carrier, that is, the amount of moisture absorbed from the atmosphere. Then, when the catalyst slurry is coated on the support, it is affected by variations in the amount of moisture, resulting in variations in the coating amount of the catalyst slurry, and there is a limit to improving and homogenizing the coating quality.

  In addition, if the amount of moisture absorbed by the carrier before coating with the catalyst slurry is excessive, the amount of catalyst slurry coating is relatively small, and the specified exhaust gas purification performance may not be obtained. Not.

  The present invention has been made paying attention to such problems, and the amount of moisture absorbed by each carrier by forcibly drying to remove moisture absorbed from the atmosphere before coating the catalyst slurry on the carrier. Thus, the present invention is intended to provide a method for producing a catalyst in which the variation in the coating amount of the catalyst slurry is reduced.

  The invention according to claim 1 is characterized in that, in a method for producing a catalyst in which a catalyst slurry is coated after the moisture-absorbing carrier is humidified, the drying treatment is forcibly performed prior to the humidification treatment of the carrier. Yes.

  The drying treatment here is performed for the purpose of removing moisture absorbed by the carrier itself before the humidification treatment, and for example, by passing hot air through the cell of the carrier as shown in claim 2 and below. Assumed to be performed.

  Further, the carrier according to claim 1 assumes that the catalyst itself has hygroscopicity before the coating of the catalyst slurry, and does not include those once coated with the catalyst slurry.

  According to the seventh aspect of the present invention, a monolith type carrier that has its own hygroscopic property or a monolith type carrier that has been previously coated with a catalyst slurry is subjected to humidification treatment and then coated with the catalyst slurry. When producing a catalyst of the type, a drying apparatus for forcibly performing a drying process prior to the humidification process of the support, and the support to be dried is cylindrical and penetrates in the axial direction. It is formed as a honeycomb having a large number of cells, and one end opening surface on the hot air blowing side of the carrier is opposed to the hot air blowing port of the hot air supply means, and the passage of hot air is restricted between them. It is characterized in that a shielding member is provided so as to positively vary the degree of drying in the radial direction of the carrier.

  The shape of the blocking member may be any shape as long as it depends on the required degree of drying. For example, when the central portion in the radial direction of the cylindrical carrier is actively dried, A plate material with a round hole is used.

  Therefore, in the first aspect of the present invention, the moisture content of each carrier immediately before the humidification treatment or the humidification is obtained by forcibly performing the drying treatment before the humidification treatment of the carrier to dry the moisture absorbed from the atmosphere. It is possible to reduce the variation in the amount of water after treatment and thus the coating amount of the catalyst slurry on each carrier. That is, by removing the water content of the carrier before the humidification treatment, the moisture content of the carrier after the humidification treatment becomes substantially uniform, and as a result, the variation in the coating amount of the catalyst slurry is reduced.

  In the invention according to claim 7, in the drying process of the carrier, the shielding member is installed between the hot air blowing port of the carrier and the hot air supply means, thereby positively controlling the degree of drying in the radial direction of the carrier. Can be different.

  According to the first aspect of the present invention, the carrier is forcibly dried before the humidification treatment, thereby avoiding the influence of variation in the amount of moisture due to natural moisture absorption, and variation in the coating amount of the catalyst slurry in each carrier. Since the catalyst slurry coating quality of each catalyst is stabilized, a catalyst having a predetermined exhaust gas purification performance can be obtained.

  According to the seventh aspect of the present invention, the carrier having a different degree of drying in the radial direction can be stably manufactured by actively changing the degree of drying in the radial direction of the carrier by the shielding member.

  1 and 2 show a preferred embodiment of the present invention. FIG. 1 shows a structure of a carrier before coating with a catalyst slurry, and FIG. 2 shows a drying treatment process, a humidification treatment process, and a catalyst slurry coating process. The outline of the manufacturing process of the catalyst including is shown, respectively.

  As shown in FIGS. 1A and 1B, the target carrier 1 is, for example, a cylindrical body made of ceramic, and has a large number of holes that will be coated with a catalyst slurry in a later step, that is, A number of cells 2 are formed so as to penetrate in the axial direction while being adjacent to each other, and are formed in a honeycomb shape as a whole. Since the carrier 1 is made of ceramic, it itself has hygroscopicity, and its diameter D is set to about 110 mm, for example, and the height H is set to about 97 mm. And this support | carrier 1 is used for the coating process of a catalyst slurry, after performing a forced drying process and a humidification process so that it may mention later.

  FIG. 2A shows the drying process of the carrier 1. The purpose of this drying treatment step is to subject the carrier 1 before being subjected to the humidification treatment step, which is the next step, to forced drying treatment with hot air.

  In this drying process, a carrier support tray 3 that supports the carrier 1 to be dried and a hot air supply device 4 are prepared as means for generating hot air and supplying it to the carrier 1 side. The carrier support tray 3 is of a horizontal rotary type, and a pair of carriers 1 are placed at positions that are 180 degrees out of phase with the rotation shaft 5 serving as the center of rotation. The portion of the carrier support tray 3 where the carrier 1 is actually placed can support the carrier 1 stably and allow passage of hot air supplied from the hot air supply device 4 as will be described later. There is a hole of a predetermined size or a mesh shape. And the hot air supply apparatus 4 is arrange | positioned at two places up and down of the carrier support tray 3 so that each carrier 1 on the carrier support tray 3 may be opposed.

  Each hot air supply device 4 accommodates a heater 7 as a heat source and a blower fan 8 in a duct 6, and the heat generated from the heater 7 is supported by the blower fan 8 as hot air of about 125 ° C., for example, from the outlet 9. 1 is blown out (the blowing direction is indicated by an arrow a in FIG. 2A).

  In the present embodiment, one of the carriers 1 on the carrier support tray 3 (the one on the right side of FIG. 2A) is blown with hot air from the lower surface 10a, which is one end opening surface, at position B, while With respect to the carrier 1 (the one on the left side of FIG. 2A), hot air is blown from the upper surface 10b which is one end opening surface at the position A, and as one end opening surface which becomes the hot air blowing side of each carrier 1 The lower surface 10a or the upper surface 10b is opposed to the outlet 9 of the duct 6 with a predetermined distance therebetween. Thus, by blowing hot air from the lower surface 10a or the upper surface 10b of each carrier 1, each carrier 1 is forcibly dried around the cell 2 to be coated with the catalyst slurry in the subsequent step.

  2A and 2B, the two carriers 1 at positions A and B are forcibly dried in parallel, and after a predetermined drying time has passed, the carrier support tray in the direction of arrow b with the rotary shaft 5 as the center of rotation. 3 is rotated 180 degrees, and the position of the carrier 1 with respect to each hot-air supply device 4 is changed, and then the drying process is performed again in parallel. By repeating the rotational movement of the carrier support tray 3 in this way, the hot air blowing direction to each carrier 1 can be switched alternately, and the degree of drying in the axial direction of each carrier 1 can be made uniform. . As described above, the rotary carrier support tray 3 and the pair of upper and lower hot air supply devices 4 form means for alternately changing the direction in which hot air passes in the longitudinal direction of the cells.

  Note that the support form of the carrier 1 is as shown in FIG. 2A as long as the structure can alternately change the hot air blowing direction with each carrier 1 and the blowing port 9 of the hot air supply device 4 facing each other. It is not limited to what is shown. Further, in the present embodiment, the heater 7 and the blower fan 8 are used as drying means, but the same function is exhibited even with a drying method using microwaves, for example.

  FIG. 2B shows the humidification process of the carrier 1. The carrier 1 that has been subjected to the previous drying process is placed on the carrier support tray 21, and a humidifying head 22 is installed above the carrier 1, and pure water is sprayed onto the carrier 1 by the humidifying head 22. After the humidification, water is forcibly absorbed in the direction of the arrow c by the negative pressure suction force of the suction device 23 installed below the carrier support tray 21 to remove excess water remaining in the cell 2. The carrier support tray 21 has a hole so that the carrier 1 is stably supported as in the case of FIG. 5A, but at least in the carrier placement region, the flow of the suction force by the suction device 23 is not hindered. It has a crack or a mesh. The suction device 23 has a suction fan 25 accommodated in a suction duct 24.

  FIG. 2C shows the coating process of the catalyst slurry on the carrier 1. The carrier 1 that has been subjected to the previous humidification process is placed on the carrier support tray 31, and a coating hopper 32 is placed on the carrier 1, and a catalyst slurry 33 is poured from the coating hopper 32 into the carrier 1, The wall 33 of the cell 1 of the carrier 1 is coated by flowing down due to its own weight. A suction device 36 containing a suction fan 35 is installed in the suction duct 34 below the carrier support tray 31 and flows down under the carrier 1 without being coated on the wall surface of the cell 3. Excess catalyst slurry 33 is recovered on the suction device 35 side. At the same time, forcible suction is performed in the direction of arrow e by the suction force of the suction device 35, and the catalyst slurry 33 that is excessively coated on the cell 2 is removed.

  Here, a drying experiment was conducted as part of the evaluation of the carrier used in the production method based on the premise that the drying treatment was forcibly performed in advance as described above.

  As the test specimen of the carrier used in the experiment, the natural moisture absorption, which is the amount of water contained in the specimen before the drying treatment, is relatively small, and the natural moisture absorption per specimen is 4 g (hereinafter referred to as the specimen). The unit representing the amount of moisture absorption per specimen is expressed as g / piece, such as 4 g / piece), and the natural moisture absorption contained in the specimen before drying treatment is relatively large. Samples having natural moisture absorption of 42 g (42 g / piece) were prepared as samples B and subjected to a drying process using the hot air supply device 4 in the drying process of FIG.

  As the drying processing conditions, the distance between the lower surface 10a or the upper surface 10b, which is one end opening surface of the samples A and B, and the blowout port 9 of the hot air supply device 4 is set to several tens mm, and based on FIG. As described above, while the hot air supply direction was changed every 5 seconds, hot air of about 125 ° C. was blown into the samples A and B for forced drying. And in the sample A and B, the outlet temperature is measured by a thermocouple at a position about 30 mm away from the other end opening surface on the hot air blowing side opposite to the hot air blowing side, and the drying time of the samples A and B The relationship between the amount of moisture absorption and the change between the drying time and the outlet temperature were examined. The measurement data are shown in Tables 1 and 2, and the graphs based on the measurement data are shown in FIGS.

  As a result, as apparent from Table 1 and FIG. 3, in both samples A and B, the moisture absorption decreased to 2 g / piece or less after about 3 minutes from the start of the drying process by blowing hot air, and the sample A and B became dry. Further, as apparent from Table 2 and FIG. 4, both the samples A and B had the outlet temperature of about 112 to 114 ° C. in about 2 minutes after the start of the drying process by blowing hot air, which is the temperature on the blowing side. Asymptotically approaching to 0 ° C., it became a stable dry state.

  Next, assuming that the catalyst is actually coated with the catalyst slurry, the natural moisture absorption amount contained in the carrier before the humidification treatment prior to the catalyst slurry coating treatment and the total moisture absorption amount of the carrier after the humidification treatment (total moisture amount) ) And the coating amount of the catalyst slurry, and whether or not there is any correlation between the coating amount of the catalyst slurry in the subsequent step when the drying treatment was performed before the humidification treatment, was measured.

  More specifically, samples A1 and A2 having a natural moisture absorption amount of 4 g / piece as a specimen of the carrier, which is relatively small in the natural moisture absorption amount contained in the specimen before the drying treatment, are the same. Samples B1 and B2 have a natural moisture absorption amount of 20g / piece per sample, and the natural moisture absorption amount contained in the sample before the drying treatment. And samples having a natural moisture absorption amount of 33 to 36 g / piece per sample were prepared as Samples C1 and C2, respectively.

  Among these, samples A2, B2, and C2 were forcibly dried before the humidification process as in the previous case. As the drying process conditions, the distance between the lower surface 10a or the upper surface 10b, which is one end opening surface of the samples A2, B2, and C2, and the outlet 9 of the hot air supply device 4 in FIG. As described above with reference to the drawing, while the hot air supply direction was changed every 5 seconds, hot air of about 125 ° C. was blown into the samples A2, B2, and C2 to perform drying treatment. The drying time was 3 minutes based on the results shown in Tables 1 and 2 and FIGS.

  For samples A2, B2, and C2, the natural moisture absorption amount before the drying treatment and the moisture absorption amount after the forced drying treatment and before the humidification treatment are measured, and the samples A1, B1, and C1 are subjected to the drying treatment. Therefore, only the natural moisture absorption before the humidification treatment was measured. The measurement data are shown in Tables 3 and 4, and the graphs based on the measurement data are shown in FIGS.

  As apparent from Table 4 and FIG. 6, the samples A2, B2, and C2 subjected to the drying treatment vary in moisture absorption amount from 4 to 33 g / piece before the drying treatment, but are humidified after the drying treatment. It can be seen that the moisture absorption before the treatment is 2 to 7 g / piece, and the variation is significantly smaller than that before the drying treatment.

  As is apparent from Table 3 and FIG. 5, the samples A1, B1, and C1 that have not been subjected to the drying process before the humidification process have no change in the moisture absorption amount of the carrier before the humidification process.

  Subsequently, each sample A1, B1, C1 and A2, B2, C2 was humidified, and the total water content contained in each sample A1, B1, C1, and A2, B2, C2 after the humidification treatment was measured. Here, as the humidification treatment, each sample A1, B1, C1 and A2, B2, C2 is immersed in pure water for 2 seconds, and in order to remove excess water adhering to each sample after the humidification treatment, (B) in FIG. The same suction device 12 was used for suction for 10 seconds.

  Here, the above-mentioned total water content is nothing but the sum of the moisture absorption amount before humidification treatment of each sample A1, B1, C1 and A2, B2, C2 and the humidification amount absorbed by the humidification treatment, and therefore the total moisture content measured. By subtracting the amount of moisture absorption prior to the humidification treatment, the amount of humidification absorbed by the humidification treatment can be calculated. And the moisture absorption amount before humidification processing about each sample A1, B1, C1 and A2, B2, and C2, the humidification amount by humidification treatment, and the data of the total moisture after humidification treatment are shown in Tables 5 and 6 in the same data. The graph based is shown in FIGS.

  As apparent from Table 5 and FIG. 7, the humidification amount by the humidification treatment in the samples A1, B1, and C1 that were not subjected to the drying treatment before the humidification treatment was 177 to 202 g / piece, and the difference between the maximum value and the minimum value Is 25 g / piece, and the variation is large, but the total moisture amount of the natural moisture absorption amount before humidification treatment and the humidification amount increased by the humidification treatment is 206 to 213 g / piece, and the difference between the maximum value and the minimum value is The variation was reduced to 7 g / piece.

  On the other hand, as apparent from Table 6 and FIG. 7, the humidification amount in the humidification treatment of samples A2, B2, and C2 that were forcibly dried before the humidification treatment was 203 to 214 g / piece, The difference between the minimum values is 11 g / piece, and the variation is even smaller. And the total moisture amount that combines the moisture absorption amount before the humidification treatment and the humidification amount increased by the humidification treatment is 210 to 216 g / piece, and the difference between the maximum value and the minimum value is 6 g / piece, and the variation is further increased. It will be small. From the above, the difference in total water content between the samples A2, B2, and C2 that have been subjected to the drying treatment and the samples A1, B1, and C1 that have not been subjected to the drying treatment is about 2 g / piece on average, It can be seen that there is almost no effect as far as the total moisture content of the carrier after the humidification treatment is concerned even if the drying treatment is not performed as a pretreatment.

  Subsequently, catalyst slurries were coated on the samples A1, B1, C1 and A2, B2, C2 subjected to the humidification process in the same manner as in FIG. And the coating amount of the catalyst slurry after a coating process was measured. The measurement data are shown in Tables 7 and 8, and the graphs based on the data are shown in FIGS.

  As is clear from Table 7 and FIG. 9, for samples A1, B1, and C1 that were not subjected to the drying treatment before the humidification treatment, the coating amount of the catalyst slurry was 34 to 40 g / piece, and the difference between the maximum value and the minimum value. Tends to increase by 6 g / piece.

  On the other hand, as apparent from Table 8 and FIG. 10, for samples A2, B2, and C2 subjected to the drying treatment before the humidification treatment, the coating amount of the catalyst slurry is 59 to 60 g / piece, and the maximum value and the minimum value. The difference is 1 g / piece, and the variation is greatly reduced. In addition, it can be seen that the coating amount of the catalyst slurry of Samples A2, B2, and C2 is about 1.6 times larger on average than the coating amount of Samples A1, B1, and C1.

  FIG. 11 shows the relationship between the moisture absorption amount before the humidification treatment and the coating amount of the catalyst slurry according to the presence or absence of the drying treatment before the humidification treatment based on the data in Tables 3 to 8 above. It can be seen that when the drying treatment is performed, the coating amount of the catalyst slurry is greatly increased as compared with the case where the drying treatment is not performed.

  That is, as apparent from Tables 7 and 8 in addition to FIG. 11, when the humidification process is performed without performing the drying process, the coating amount of the catalyst slurry increases when the moisture absorption amount of the carrier before the humidification process is small. It can be seen that when the moisture absorption amount before the humidification treatment is large, the coating amount of the catalyst slurry tends to decrease.

  On the other hand, when the drying process is performed before the humidification process as in the present embodiment, it can be seen that the coating amount of the catalyst slurry is almost constant regardless of the natural moisture absorption amount before the drying process.

  This phenomenon is likely to occur when the humidification process is performed in a short time, and even if the total moisture amount, which is the sum of the moisture absorption amount before the humidification treatment and the humidification amount by the humidification treatment, is substantially equal (for example, in Table 5). 206 to 213 g / piece), which is based on the fact that the coating amount of the final catalyst slurry becomes a large difference (see FIGS. 7 to 10).

  In other words, the moisture absorbed by the carrier from the atmosphere (natural moisture absorption) is widely dispersed throughout the particles forming the catalyst layer, while inhibiting the water absorption force mainly due to the capillary action caused by the pores of the catalyst layer, It is presumed that the moisture humidified in the humidification step is distributed shallowly on the surface of the particles forming the catalyst layer, and it is difficult to inhibit the original water absorption capacity of the carrier. As a result, during the coating process of the catalyst slurry after the humidification process, the water absorption capacity of the carrier deprives the moisture in the catalyst slurry, and the catalyst slurry deprived of the moisture at this time becomes less fluid, and the cell surface of the carrier It is thought that it becomes easy to fix to. Therefore, it is presumed that when the carrier is forcibly dried in advance before the humidification treatment as in the present embodiment, the water absorption inhibition factor of the carrier itself is eliminated, and the amount of slurry coating is further increased.

  Therefore, according to the manufacturing method of the present embodiment, the coating amount of the catalyst slurry is greatly increased as compared with the conventional manufacturing method, which can contribute to the improvement of the exhaust purification performance of the catalyst.

  FIG. 12 shows another example of a drying apparatus applied to the drying process of FIG. 2A as the second embodiment of the present invention.

  As shown in FIG. 12, an interval of, for example, several mm to several tens mm is secured as a separation distance f between the outlet 9 of the hot air supply device 4 and the carrier 1 placed on the carrier support tray 41. A ring-shaped shielding plate 42 is installed as a shielding member so as to cover the peripheral portion of the lower surface 10a which is one end opening surface of the carrier 1 immediately before the opening 9. The blocking plate 42 is formed of a rigid material that does not deform or change even when hot air of about 125 ° C. is received.

  The shielding plate 42 has a rectangular shape, and a circular ventilation hole 43 having an area which is, for example, about ¼ of the opening area of the lower surface 10a which is one end opening surface of the carrier 1 is provided at the center thereof. ing. By inserting the shielding plate 42 so as to be concentric between the lower surface 10a of the carrier 1 and the outlet 9, hot air is blown into the carrier 1 in the direction of the arrow g from the hot air supply device 4 as hot air supply means and forced. When the drying process is performed, the flow of hot air at the peripheral edge of the lower surface 10a of the carrier 1 on the hot air blowing side is blocked. This means that the center cell of the carrier 1 is more easily dried by blowing hot air than the peripheral cell, and as a result, the radial center of the carrier 1 is more than the peripheral part. It will be forced to dry actively.

  That is, the degree of drying in the radial direction of the carrier 1 is preferentially changed in advance, and the degree of dryness in the central part in the radial direction of the carrier 1 is set higher than that in the peripheral part in advance, so that the catalyst slurry in the next step. In the coating, the coating amount at the central portion in the radial direction can be positively increased as compared with the peripheral portion. As a result, when the catalyst manufactured by the manufacturing method is applied to, for example, an exhaust gas purification system, the purification performance at the central portion of the cross section of the exhaust gas passage that is functionally important can be further enhanced.

  In this type of catalyst manufacturing method, after the catalyst slurry is once coated on the carrier, the catalyst slurry may be coated again through the drying process, the firing process and the humidification process. Of course, it is possible to perform a drying process using the above-described drying apparatus before the humidifying process is performed on the carrier.

  Here, the main effects in the present embodiment other than those described in the column “Effects of the Invention” will be described as follows together with the cause of the occurrence.

  (1) By actively varying the drying degree in the radial direction of the carrier 1 to increase the drying degree of the central part from the peripheral part, the coating amount of the catalyst slurry 33 is also different between the peripheral part and the central part. As a result, the total coating amount required for one carrier 1 can be reduced to improve the material yield and reduce the manufacturing cost.

  (2) By subjecting the one end opening surface on the hot air blowing port side of the carrier 1 and the blowing port 9 of the hot air supply device to face each other, the hot air can be smoothly passed through the cell 2, for example, drying The occurrence of unevenness in the degree of drying in the radial direction can be prevented as compared with the case where the drying process is performed without considering the hot air blowing direction in the furnace or the like.

  (3) By alternately changing the hot air passage direction in the longitudinal direction of the cell 2 in the carrier 1, the occurrence of unevenness in the degree of drying in the longitudinal direction is generated more than in the case where hot air is passed from one specific direction to the longitudinal direction of the cell 2. Can be prevented.

  (4) When the carrier 1 is subjected to a drying process, the drying degree of the carrier 1 is positively limited by using the shielding plate 42 in combination, for example, in the radial direction, the degree of drying in the central portion is larger than that in the peripheral portion, The coating amount of the catalyst slurry can be increased.

  (5) As shown in FIG. 2, when two carriers are placed on the rotating carrier support tray 3 with a phase difference of 180 °, the carrier support tray 3 is sandwiched between two places above and below it. A hot air supply device 4 serving as a hot air supply means is arranged so as to face each carrier 1, and the carrier support tray 3 is rotated in the direction of arrow B while the drying treatment of the two carriers 1 is performed in parallel. Thus, for example, the forced drying process in the mass production process of the catalyst can be performed efficiently, and the productivity is improved.

FIG. 1 shows a schematic structure of a carrier as a preferred embodiment of the present invention, in which (A) is a plan view of the carrier and (B) is a front view of the carrier. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic explanatory diagram of a catalyst production method including a carrier drying treatment step, a humidification treatment step, and a catalyst slurry coating treatment step as a preferred embodiment of the present invention. It is explanatory drawing which shows the relationship between the moisture absorption amount of a support | carrier, and drying time in the drying process performed before a humidification process. It is explanatory drawing which shows the relationship between the hot air temperature in a support | carrier exit, and drying time in the drying process performed before a humidification process. It is explanatory drawing which showed the natural moisture absorption amount (= moisture absorption amount before a humidification process) of each support | carrier (sample A1, B1, C1) which does not perform a forced drying process before a humidification process. It is explanatory drawing which showed the natural moisture absorption amount (moisture absorption amount before a drying process) and the moisture absorption amount before a humidification process (after a drying process) of each support | carrier (sample A2, B2, C2) which performed the drying process before a humidification process. . It is explanatory drawing which showed the moisture absorption amount before the humidification process of each support | carrier which does not perform a drying process before a humidification process, and the humidification amount by a humidification process. It is explanatory drawing which showed the moisture absorption amount before the humidification process of each support | carrier which performed the drying process before the humidification process, and the humidification amount by a humidification process. It is explanatory drawing which showed the coating amount of the catalyst slurry of each support | carrier which does not perform a drying process before a humidification process. It is explanatory drawing which showed the coating amount of the catalyst slurry of each support | carrier which performed the drying process before the humidification process. It is explanatory drawing which shows the relationship between the moisture absorption amount before a humidification process, and the coating amount of a catalyst slurry according to the presence or absence of the drying process before a humidification process. It is a schematic explanatory drawing which shows another example of a drying process (drying apparatus) as 2nd Embodiment of this invention, (A) is the front explanatory drawing, (B) is the plane explanatory drawing similarly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Carrier 2 ... Cell 3 ... Carrier support tray 4 ... Hot air supply device (hot air supply means)
9 ... Blowout port 10a ... Lower surface (one-end opening surface)
10b ... Upper surface (one-end opening surface)
33 ... Catalyst slurry 41 ... Carrier support tray 42 ... Shield plate (shield member)
43 ... Ventilation hole

Claims (8)

  In a monolith type catalyst manufacturing method in which a catalyst slurry is coated after a moisture treatment is applied to a monolith type carrier having hygroscopicity, the monolith type is forcibly subjected to a drying treatment prior to the humidification treatment of the carrier. A method for producing the catalyst.   The carrier is a cylindrical one made of ceramic and formed as a honeycomb having a large number of cells penetrating in the axial direction, and is dried so that the degree of drying in the radial direction of the carrier is different. The method for producing a monolith type catalyst according to claim 1, wherein the treatment is performed.   The method for producing a monolith type catalyst according to claim 2, wherein the drying process is performed so that the degree of drying is greater in the central part than in the peripheral part in the radial direction of the carrier.   4. The method for producing a monolith type catalyst according to claim 2, wherein a drying process is performed by passing hot air through the cell of the carrier.   5. The monolith type catalyst according to claim 4, wherein, when the hot air is passed through the cell of the carrier to perform the drying treatment, the monolith type catalyst is treated by alternately changing a passing direction of the hot air in a longitudinal direction of the cell. Manufacturing method.   When performing a drying process by passing hot air through the cell of the carrier, the periphery of one end opening surface on the hot air blowing side of the carrier is covered with a shielding member, and the area through which the hot air passes is limited. The method for producing a monolith type catalyst according to any one of claims 3 to 5, wherein the degree of drying in the radial direction of the catalyst is positively varied. When producing a monolithic type catalyst by coating the catalyst slurry after humidifying the monolithic type carrier having its own hygroscopic property or the monolith type carrier previously coated with the catalyst slurry. A drying device for forcibly performing a drying process prior to the humidifying process of
The carrier to be dried is cylindrical and formed as a honeycomb having a large number of cells penetrating in the axial direction,
The degree of dryness in the radial direction of the carrier by placing one end opening surface on the hot air blowing side of the carrier and the hot air blowing port of the hot air supply means facing each other and installing a shielding member for restricting the passage of hot air between them A drying device characterized by positively differing between the two. 8. The drying apparatus according to claim 7, further comprising means for alternately changing the passing direction of the hot air in the longitudinal direction of the cell.

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