JP4516521B2 - Catalyst production method - Google Patents

Description

  The present invention relates to a method for producing a titanium oxide catalyst which can exhibit its catalytic function even in the dark, and in particular has a deodorizing and fading function for various urinations.

  It is widely known that titanium oxide has a photocatalytic function, and various means for expanding the catalytic function of titanium oxide in various fields have been proposed.

  For example, Patent Document 1 discloses that titanium oxide is doped with nitrogen or sulfur to absorb visible light having a longer wavelength than ultraviolet light, and reacts with water contained in a water storage substance to develop hydrophilicity. It is disclosed.

  Patent Document 2 discloses that the surface of titanium oxynitride is visible when at least one functional group or impurity selected from amino group, amide group, azide salt, cyanate salt, cyanate salt, and carboxylate salt is present. It has been disclosed that the photocatalytic performance during light can be greatly improved.

  Patent Document 3 discloses a resin molded body in which a photocatalyst layer is formed by spraying a photocatalyst particle dispersion on titanium nitride.

  Patent Document 4 discloses that titanium oxide has a deodorizing function.

  Furthermore, Patent Document 5 discloses that nitrogen-containing titanium oxide crystals obtained by firing a titanium complex in which a nitrogen-containing organic compound is coordinated to metallic titanium are used as a decomposing agent for environmental pollutants. .

  However, the development of any of the above titanium oxide or titanium oxynitride catalytic reactions basically utilizes the photocatalytic action under visible light.

On the other hand, the inventor of the present application obtained a knowledge in Patent Document 6 that titanium dioxide exerts its catalytic action in a dark place under certain conditions, and a mixture mainly composed of graphite silica powder as a carrier. It has been disclosed that a decolorant or deodorizer for livestock animal urine can be obtained by coating a formed body comprising a titanium dioxide powder or a mixture of titanium dioxide powder and graphite silica powder.
JP 2001-207082 A JP 2002-321907 A JP 2003-154546 A JP 2004-100319 A JP 2004-141739 A JP 2005-28881A

  An object of the present invention is to further increase the catalytic function of the titanium oxide catalyst in the dark.

  Another object of the present invention is to provide a titanium oxide catalyst suitable for deodorization / decolorization of livestock urine.

  Still another object of the present invention is to provide a treatment method for increasing the function of a titanium oxide catalyst in a dark place as a decolorizing / deodorizing agent.

  The present invention has been completed under the knowledge that the function as a catalyst in a dark place of a mixture of shirasu (aluminosilicate glass powder), graphite silica and titanium oxide is greatly improved by the treatment method. did.

  That is, in the method for producing a titanium oxide catalyst of the present invention, shirasu and graphite silica are mixed and molded into a ball shape, and a mixture of shirasu, graphite silica powder and titanium oxide powder is attached to the surface of the catalyst, followed by reduction firing. Then, a titanium oxide solution is applied to the surface of the ceramic ball and fired to form a titanium oxide coating layer on the surface of the ceramic ball.

  Graphite silica used in the present invention is a natural ore produced in a fault crushing part in the Pre-Tertiary black hard mudstone, a black matter having a carbon content of several percent and mainly composed of silicic acid. Specificity as a property is known to radiate mid-infrared rays with a high emissivity at room temperature (growth rays with a wavelength of 4 μm to 14 μm), and their radiation characteristics are known to be curves that are very close to black bodies as ideal substances It is what.

  When this graphite silica is mixed with shirasu and formed into a ball shape, the graphite silica raw material, which is a natural ore, is pulverized into powder.

  Then, the mixture is formed into a ball shape of about 2 to 3 mm using shirasu and graphite silica powder, and a mixture of shirasu, graphite silica powder and titanium oxide powder is adhered to the surface, and then reduced and fired to form a ceramic. . This reduction firing is preferably performed at a temperature of about 1000 to 1200 ° C. Note that the step of attaching the mixture of shirasu, graphite silica powder and titanium oxide powder to the surface of the ball-shaped mixed molded body can be omitted.

  The obtained ceramic ball is used as a carrier, a titanium oxide solution is applied to the surface and fired to form a titanium oxide coating layer on the ceramic ball surface. This firing may be performed in an oxidizing atmosphere or a reducing atmosphere. Firing in an oxidizing atmosphere is preferably performed at a temperature of about 350 to 550 ° C. Firing in a reducing atmosphere is preferably performed at a temperature of about 900 to 1000 ° C.

  If necessary, a titanium oxide solution may be applied to the surface of the ceramic ball and fired, followed by nitriding, and the coating layer on the surface of the ceramic ball may be a titanium nitride layer or a layer containing titanium nitride.

  The titanium oxide-based catalyst thus prepared is remarkably superior in catalytic ability in the dark compared with other methods, for example, those obtained from a mixed powder of shirasu and graphite silica powder.

  Hereinafter, an embodiment of the present invention will be described with reference to an example in which the catalyst obtained by the production method of the present invention is used for wastewater treatment in a pig farm.

(1) Catalysts used Shirasu and graphite silica powder were mixed into a ball shape of about 2 to 3 mm, and a mixture of shirasu, graphite silica powder and titanium oxide powder was adhered to the surface, and then reduced at 1090 ° C. Firing into ceramics. The obtained ceramic balls (ball core part is shirasu and graphite silica, surface layer part is a compound of shirasu / graphite silica / titanium) as a carrier, a commercially available titanium oxide solution is applied to the surface, and a reducing atmosphere at 900 ° C. The catalyst that was calcined below and nitrided was used as the catalyst.

(2) Liquid to be treated The wastewater immediately before the off-site discharge, which was biologically treated at company J pig farm and still contains a large amount of organic matter such as pigment, was used as the liquid to be treated.

(3) Testing machine Fig. 1 shows the testing machine used in the examples. The tester has 5 tank contact parts 1 to 5 having a water flow cross-sectional area of 0.005 m ² (0.05 m × 0.1 m) and a contact length of 0.50 m for contacting the catalyst to be used and the liquid to be treated. A direction-flow acrylic testing machine was used.

(4) Test method The used catalyst previously immersed in the liquid to be treated for 24 hours or more is filled in the contact portions 1 to 5 of the five tanks, and the liquid to be treated (flow rate 50 cc / min) is filled in the first tank with an underwater pump. Guided to the lower part of the contact part 1 and passed through the contact part 1 in an upward flow, the passing liquid obtained at the upper part is guided to the lower part of the contact part 2 of the next second tank and allowed to pass through the contact part 2 of the tank. A continuous water flow test was conducted. The 3rd-5th tank was made into the same contact system, and the final treated water was obtained in the 5th tank upper part. After a water flow test for a total of 100 hours or more, the liquid to be treated (raw water) and the water passing through each tank were collected as samples and analyzed. The reason for sampling after passing water for 100 hours or more is that coconut husk activated carbon became saturated after about 25 hours in the same test as described above, and the passing water in the fifth tank exhibited a pigment equivalent to the raw water. The pre-watering time which requires the time was set.

(5) Analysis items Table 1 shows the analysis items.

(6) Test results The test results are shown in Table 2 and FIG.

  In this test, the water passing time per tank is about 20 minutes, and therefore, the third tank passing point (contact length 1.50 m) corresponds to a time point of 1 hour. At this point in time, the chromaticity was 97%, the total organic carbon content (TOC) was 80%, and the dissolved oxygen content (DO) was 59%, confirming the effectiveness of the catalyst used.

  In addition, as a result of investigation and analysis of organic and inorganic nitrogen, organic nitrogen was reduced by about 85% at the passing point (contact length: 2.50 m) of the final fifth tank, as expected. Furthermore, although the decrease of inorganic nitrogen was not expected at all, nitrate nitrogen occupying most of the inorganic state was reduced by about 25% at the passing point of the fifth tank. It is considered that organic nitrogen was gradually decomposed and decreased in the first to fifth tanks by the catalytic reaction used. The cause of the decrease in inorganic nitrate nitrogen is not clear, but there are also research results that convert nitrate ions into nitriding gas by a reduction reaction using an electric field using a semiconductor supporting titanium oxide. It is thought that there may be a reduction reaction in a small electric field peculiar to the catalyst used in the test.

The test machine used for the process test of the to-be-processed liquid is shown. The analysis result of the to-be-processed liquid processed with the testing machine of FIG. 1 is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact part of 1st tank 2 Contact part of 2nd tank 3 Contact part of 3rd tank 4 Contact part of 4th tank 5 Contact part of 5th tank

Claims (3)

  Shirasu and graphite silica are mixed and molded into a ball shape, and a mixture of shirasu, graphite silica powder, and titanium oxide powder is attached to the surface and reduced and fired to form a ceramic ball as a carrier. A method for producing a catalyst in which a titanium oxide solution is applied and calcined.   A method for producing a catalyst in which shirasu and graphite silica are mixed and molded into a ball shape, reduced and fired to form a ceramic ball as a carrier, and then a titanium oxide solution is applied to the surface of the ceramic ball and fired.   The method for producing a catalyst according to claim 1 or 2, wherein a titanium oxide solution is applied to the surface of the ceramic ball, fired, and then subjected to nitriding treatment.

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