JPH0336574B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminated corrugated carrier made of a sheet of synthetic inorganic fibers and suitable as a carrier for a gas phase reaction catalyst. Various types of catalyst carriers made of sheets of synthetic inorganic fibers are already known. The present inventors have already made a sheet out of a slurry containing synthetic inorganic fibers, organic fibers, and an organic binder, formed this sheet into a laminated corrugate, and then added colloidal silica or ethyl silicate to this laminate. After impregnating the sheet, this is converted into silicic acid gel, which is then fired at a high temperature to burn the organic fibers and organic binder in the sheet, so that the synthetic inorganic fibers are mutually bonded by the silicic acid gel. proposed a laminated corrugate-like carrier that is bonded (Japanese Unexamined Patent Publication No. 136656/1983). As shown in the figure, this laminated corrugated carrier consists of a flat plate called a liner 1 made of synthetic inorganic fiber sheets bonded by silicic acid gel, and a core 2.
It has a laminated structure formed by alternately laminating and bonding corrugated plates called ``corrugated sheets'', and as described in the above publication,
It has various advantages such as being lightweight and easy to handle, and since it is made of inorganic fibers, it has excellent heat resistance and a large surface area. However, the only drawback is that the synthetic inorganic fibers that make up the fiber sheet is generally inferior in buckling strength and tensile strength, which means that the mechanical strength is insufficient. In particular, such a laminated corrugated carrier is strongly required to have excellent compressive rupture strength, since it is filled in a catalyst basket and used in a gas phase reaction. However, such laminated corrugated carriers are usually produced by bonding a liner to one or both sides of a core to form a corrugate, and then laminating and bonding this in multiple stages. At this time, the peaks of each core are It is actually impossible to match each other, and generally, as shown in the figure, the peaks 3 of the center core are arranged randomly between each corrugate, so when compressing such a laminated corrugate-like carrier, Compression failure occurs more easily than in a structure in which the peaks of the center core coincide between each corrugate. Of course, as will be described later, the strength can be improved to some extent by impregnating such a laminated corrugated structure with colloidal silica or the like and repeatedly curing it. The large porosity of the corrugated carrier is reduced, and as a result, it becomes difficult to support carrier materials and catalyst materials,
A problem arises in which the carrier performance and catalyst performance become poor. The present invention was made in order to solve the above-mentioned problems in a laminated corrugated carrier for catalysts made of a sheet of synthetic inorganic fibers, and an object of the present invention is to provide a laminated corrugated carrier whose compressive strength is dramatically improved. With the goal. The present invention relates to a laminated corrugate-like carrier for catalysts in which liners made of synthetic inorganic fiber sheets and cores are alternately laminated and bonded.The pitch of the core is a, the pitch between the liners is b, and the thickness of the liners is When c and the thickness of the core are d, 1/30≦c/a≦3/20, 1/20≦d/b≦1/5 and 3/10≦b/a≦10/10. It is characterized by In the present invention, the synthetic inorganic fibers include alumina fiber, silica fiber, alumina-silica fiber,
Zirconia fibers, glass fibers, etc. are used, but
This effect is particularly noticeable in alumina fibers, silica fibers, alumina-silica fibers, and zirconia fibers that have relatively poor buckling strength and tensile strength. The laminated corrugated catalyst carrier according to the present invention is produced by forming a sheet from an aqueous slurry containing synthetic inorganic fibers, organic fibers, and an organic binder as described above, and corrugating this sheet to form a single-sided or double-sided corrugated structure. Furthermore, after laminating and bonding these corrugates together to have a predetermined capacity,
This structure is obtained by hardening the structure with silicic acid gel and then firing it at a high temperature. Here, the organic fibers are preferably hydrophilic, water-dispersible, and non-thermoplastic cellulose fibers such as rayon fibers and wood pulp, but thermoplastic vinylon fibers, polyethylene fibers, Various synthetic fibers such as acrylic fibers and polyester fibers can also be used. These fibers have a fiber strength of 3 deniers or less and a fiber length of 3 denier from the viewpoints of dispersibility in water, strength and corrugation processability of the resulting fiber sheet, and improved porosity after firing.
~10 mm is preferred. The organic binder is used to improve the dispersibility of fibers in water, bond the fibers to each other, increase the strength of the resulting sheet, and improve corrugating processability and shape retention. Fibrous polyvinyl alcohol resin is preferably used because it has a good yield during papermaking, but other resins include, for example,
Acrylic fiber, vinyl acetate fiber, ethylene-vinyl acetate copolymer resin, urea resin, melamine resin,
Carboxymethylcellulose, starch, etc. can be used in any form such as an aqueous solution, emulsion, powder, or fiber. In the present invention, each of the above-mentioned components is dissolved or dispersed in water to obtain a papermaking raw material, and the blending ratio of each of the above-mentioned components is usually 80 to 96% by weight of synthetic inorganic fibers,
Organic fiber: 2-10% by weight, organic binder: 2-10% by weight
10% by weight, and these make up a total of 0.1 to 0.3% by weight.
slurry by a conventional method to have a certain concentration,
Next, a sheet having a thickness of 0.15 to 0.50 mm and a density of 0.1 to 0.5 g/cm ³ (all values for dry material) is produced using a conventional paper machine such as a Fourdrinier type or a circular wire type. In order to corrugate the synthetic inorganic fiber sheet obtained in this manner, the liner and the core are bonded together with an adhesive using, for example, a single-stage corrugating machine. Of course, a double-sided corrugated structure can be used as required. In this case, the temperature of the corrugating machine is preferably about 120 to 190°C in order to improve the shape retention of the core and dry the adhesive. When this temperature is too low, it is difficult to form the synthetic inorganic fiber into a corrugated core due to its rigidity;
If it is too high, the organic fibers and organic binder will deteriorate, resulting in poor shape retention. The adhesive used in this corrugating process is as described below.
Since the obtained corrugated laminate is fired at a high temperature after this processing, organic adhesives are not suitable for use, and it is necessary to use inorganic adhesives. Furthermore, it is not preferable to use adhesives that contain components that may poison the catalyst, such as alkali metal ions. Therefore, specific examples of adhesives that can be preferably used in the present invention include the following. (a) Purified bentonite or water with titanium oxide, silica powder, alumina sol, etc. added to it; (b) Water with silica powder or alumina powder added; (c) Colloidal silica added to alumina powder and kaolin. and (d) water with zirconia powder and colloidal silica added. Such adhesives include, for example, FF adhesive (Nichias Co., Ltd.), Sumiceram (Sumitomo Chemical Co., Ltd.), Bond.
It can be obtained as a commercial product such as X (Nissan Chemical Industries, Ltd.). Next, in order to obtain a laminated corrugate-like structure by laminating and bonding the corrugates processed in this way, the adhesive is applied to the tips of the ridges of the core and pressed together. The amount of adhesive applied is 3 to 10
g/m ² (solid content equivalent) is desirable; if it is too small, the adhesive strength will be low, and if it is too large, it will block the voids in the sheet, which is not preferable. After such lamination processing, a curing treatment is further performed in order to provide strength performance as a carrier. That is, the corrugated laminated structure obtained above is impregnated with colloidal silica or ethyl silicate, and then converted into a silicic acid gel. When impregnated with colloidal silica, curing is completed by drying at 150-170°C. When impregnated with ethyl silicate, silicic acid gel is produced by hydrolyzing it. For this purpose, for example, the sheet may be exposed to high-temperature steam, or a method such as adding hydrochloric acid or the like as a catalyst to ethyl silicate in advance and leaving it for several hours after impregnation is adopted. Note that the method of impregnating the sheet with ethyl silicate can process the entire sheet more uniformly than the method of impregnating it with colloidal silica. In either method, the amount of impregnation is preferably about 60 to 120 parts by weight of silica per 100 parts by weight of the laminated corrugate structure. If the amount of impregnation is excessive, the strength of the laminate will increase, but the porosity will decrease and the surface area will decrease, which is not preferable. After the silicic acid gel is generated and subjected to a curing treatment as described above, when the laminate is fired, the organic fibers and organic binder disappear, and the synthetic inorganic fibers are removed from the sheet bonded with the silicic acid gel. A laminated corrugated carrier is obtained. By manufacturing using this method, the porosity of the resulting carrier can be reduced.
It can be 75% or more. Here, the porosity is [1-(apparent density/true density)]×100(%)
It has the same meaning as porosity, which generally indicates the degree of porosity of paper. The catalyst carrier according to the present invention is a laminated corrugated carrier obtained as described above, in which the pitch of the core is a, the pitch between the liners is b, the thickness of the liner is c, and the thickness of the core is as described above. d
When 1/30≦c/a≦3/20, 1/20≦d/b≦1/5 and 3/10≦b/a≦10/10, the strength can be dramatically improved. I was successful in doing so. Note that the pitch a between the cores and the pitch b between the liners are naturally limited due to the workability of the corrugating machine, and normally a is 1 mm.
or more and 15 mm or less, and b is 0.5 mm or more and 10 mm or less. Therefore, the specific ranges of c and d are also determined from the above relationship. In the present invention, it is not necessarily clear why the strength of the laminate is improved by defining the relationships among a, b, c, and d as described above, but
c/a specifies the relationship between the moment that the liner receives from the peak of the upper or lower center core and the force that supports this moment by the tensile strength of the liner,
d/b and b/a are considered to specify the relationship between the compressive force that the molded body receives and the force that the core supports,
By specifying these three ratios, the porosity can be
Even though it is 75% or more, it is possible to obtain a laminated corrugate-like carrier with excellent strength. If each of the above ratios is too small, the strength of the laminated corrugated carrier will not be sufficient, and even when b/a is increased, the strength of the carrier will not be sufficient. On the other hand, if c/a and d/b are increased, the strength of the laminated corrugated carrier increases, but at the same time the weight increases, and the strength does not increase in proportion to the increase in the above ratio. So,
It is not preferable to increase it beyond the above range. Furthermore, if c/a and d/b are too large, during corrugation processing of synthetic inorganic fiber sheets, the core may be tensilely broken by the molding section of the corrugating machine, or the liner and core may become bonded to each other. is insufficient, and as a result, the strength of the obtained laminate is rather poor, which is not preferable. In the present invention, the above ratios are preferably 1/20≦c/a≦1/10, 1/15≦d/b≦1/6 and 4/10≦b/a≦9/10, particularly preferably are 1/15≦c/a≦8/90, 1/12≦d/b≦1/7 and 5/10≦b/a≦8/10, and when within these ranges, it has particularly excellent strength. A carrier can be obtained. As described above, according to the present invention, by specifying the relationships among a, b, c, and d, even when the reactions of the peaks in the core do not match, the catalyst can be filled into a predetermined basket. In this case, it is possible to obtain a catalyst carrier with significantly improved strength that does not cause compression failure. A laminated corrugate catalyst according to the present invention can be obtained by supporting a required catalyst material and, if necessary, a carrier material on such a catalyst carrier. Since the catalyst carrier according to the present invention has a porosity of 75% or more,
The viscosity of the solution or slurry containing the catalyst material (and support material) at room temperature is 1000 centipoise or less, preferably 300 centipoise or less, particularly preferably
By setting the pressure to 100 centipoise or less, the catalyst material (and carrier material) can penetrate into the inside of the wall of the carrier. Therefore, according to the catalyst carrier of the present invention, the decrease in activity due to abrasion of the catalyst due to dust contained in the reaction gas is small, and when the catalyst reaction rate is diffusion-limited, the depth from the catalyst surface of the catalytic reaction zone is determined by the reaction, but in order for the catalyst to participate most effectively in the reaction, the amount of catalyst needs to be present in accordance with the reactant in the reaction zone. Therefore, according to the catalyst of the present invention, the porosity but
It has the advantage of being as high as 75% or more, making it possible to support the catalyst deep inside the carrier, and requiring only a small amount of catalyst to carry out the reaction at the required rate. The catalyst carrier of the present invention and the catalyst obtained therefrom are suitable for gas phase reactions, and the reaction targets are not particularly limited, but for example, nitrogen oxides contained in boiler exhaust gas, etc., and ammonia are used as reducing agents. It can be suitably used for reduction and removal as When the laminated corrugated catalyst of the present invention is used for such a reaction, examples of the carrier material include alumina, titanium oxide, silica, etc.
Catalyst materials include vanadium, tungsten,
Oxides of molybdenum, copper, iron, manganese, cobalt, chromium, etc., platinum, palladium, ruthenium, etc. are used. Note that, if necessary, only the carrier material may be supported first, and then the catalyst material may be supported, or these may be supported simultaneously. Furthermore, if necessary, these can be repeatedly supported on the carrier. In order to support these catalyst materials (and support materials) on a carrier, as described above, the carrier is impregnated with a solution or slurry containing them, dried, and then heated at a temperature of, for example, 300 to 800°C in an oxidizing atmosphere. It should be fired at a certain temperature. The present invention will be explained below by giving examples and comparative examples of the present invention. Example 1 Alumina-silica fiber (Fine Flex manufactured by Nichias Co., Ltd., diameter 1.5-3.0 μm, length 5-30 mm)
85 parts by weight, rayon fiber (1.5 denier, 5 mm)
After dispersing 5 parts by weight of beaten wood pulp, 2 parts by weight of beaten wood pulp, and 8 parts by weight of acrylic resin in 340 times the weight of water, paper was made by a conventional method using a circular mesh paper making machine, and the average thickness was 0.2 mm and 0.25 mm, respectively. mm, 0.3mm, 0.4mm, 0.5
Sheets of mm, 0.65 mm, 0.7 mm, 0.8 mm, 1.0 mm and 1.2 mm were obtained. The sheets thus obtained were each fed in one stage to a corrugating machine, and the center pitch and liner pitch were 7.5 mm and 3.6 mm, 8.5 mm and 5.0 mm, 10.9 mm and 6.6 mm at 160 to 170°C, respectively. A single-sided cardboard was obtained. Next, cut these single-sided cardboard to 150 mm length and width, and use a roller to
FF adhesive was applied and stacked in multiple layers to a height of approximately 150mm. Next, colloidal silica (30% silica solids)
After drying at 150°C, the organic components in the laminated corrugate are removed by baking in an oxidizing atmosphere at 800°C to produce laminated corrugates with various c/a, d/b and b/a ratios. A carrier was obtained. However, in Reference Example 2, the carrier after firing was treated with colloidal silica (silica solid content: 20%) and was further subjected to wash coating three times. 3 parts by weight of vanadium pentoxide, average particle size 1 μm,
A slurry with a viscosity of 12 centipoise at room temperature consisting of 30 parts by weight of titanium oxide with a specific surface area of 75 m ² /g, 18 parts by weight of silica sol (silica solid content 20%) and 58 parts by weight of water was prepared, and each of the carriers obtained above was mixed. 2 to this slurry
Wash coat twice and dry at 120℃ and then 400℃
The mixture was calcined for 3 hours to prepare a catalyst. Table 1 shows the dimensions, weights, and compressive rupture strengths of each of the carriers and catalysts obtained as described above. It is clear that the carrier and catalyst of the present invention have dramatically improved compressive fracture strength. still,
Comparative Example 4 shows that when the ratio is outside the range specified by the present invention, it is necessary to support a very large amount of catalyst in order to have almost the same strength as the present invention. Example 2 This example shows that the catalyst according to the present invention exhibits little decrease in catalytic activity and is highly active. Commercially available cordierite honey weighing 2490g

【table】

[Table] A cam (through hole equivalent diameter 3.6 mm, porosity 36%) was immersed in a slurry containing the same carrier material and catalyst material as in Example 1, and after removing excess slurry, it was dried and this operation was carried out. The catalyst was prepared in three replicates.
The weight of this catalyst was 3435g. Next, the present invention catalyst 4 of Example 1 (porosity of carrier 78%) and the catalyst obtained as a comparative example obtained above were each charged into an actual gas tester that burns heavy oil A, and the catalyst performance was investigated. Ta. Gas composition is nitrogen oxide
180ppm, oxygen 120ppm, dust content 80
mg/Nm ³ and equimolar ammonia to the nitrogen oxides in the gas was added to the gas, and the nitrogen oxide removal rate of each catalyst was changed over time at a temperature of 350°C and a space velocity of 10,000/hr (NTP). I looked into it. The results are shown in Table 2.

[Table] Although the catalyst according to the present invention supports almost the same amount of catalyst material and carrier material as the comparative example catalyst, it is clear that the catalyst according to the present invention maintains higher catalytic performance over a longer period of time. be.

[Brief explanation of the drawing]

The drawing is a front view showing the main parts of a laminated corrugated catalyst carrier. 1...Liner, 2...Center core, 3...Mountain part.

Claims (1)

[Scope of Claims] 1. A laminated corrugate-like carrier for a catalyst in which liners made of synthetic inorganic fiber sheets and cores are alternately laminated and bonded, wherein the pitch of the core is a, the pitch between the liners is b, and the liner is When the thickness of the core is c and the thickness of the core is d, 1/30≦c/a≦3/20 1/20≦d/b≦1/5 and 3/10≦b/a≦10/10 A laminated corrugated carrier for a catalyst, characterized in that: