JPS6223426A - Treatment of exhaust gas containing cyanide compound - Google Patents

Abstract

PURPOSE:To surely contact a cyanide compound with a catalyst, by passing exhaust gas containing a cyanide compound through a catalyst filter wherein a noble metal catalyst is supported by a cloth like carrier comprising a quartz glass fiber containing 90% or more of a silica component. CONSTITUTION:A catalyst filter is prepared by a method wherein 2,400-7,200 quartz glass fibers with a diameter of about 9mum and silica content of 90% or more having a noble metal catalyst uniformly adhered thereto in a thickness of 0.2mum are gathered to be formed into one yarn which is, in turn, woven to form cloth and 10-20 cloths are superposed to be formed into a corrugated filter. Because exhaust gas containing a cyanide compound passes through said filter, the cross-sectional area of the min. one section through which gas flows in reduced to 1/100 or less as compared with a case using a pellet type catalyst carrier and the catalyst is surely contacted with the gas stream to enhance treatment capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for treating waste gas containing cyanide compounds, and more particularly to a method for purifying waste gas using a special catalyst filter.

(Prior Art) Today, the content of cyanide compounds in waste gas from combustion equipment such as garbage incinerators and various sludge incinerators has become a problem in urban environmental facilities, and the causes of their occurrence are as follows. The former is caused by the thermal decomposition of urethane resin contained in garbage.

In incineration facilities for sludge produced from various domestic wastewaters such as sewage sludge and sewage sludge, cyanide compounds are produced due to incomplete combustion of the nitrogen compounds (proteins and amines) they contain, that is, when they are decomposed at high temperatures in a reducing atmosphere. I also know what to do.

Conventionally, as a method for removing trace amounts of cyanide,
N various chemical cleaning methods (absorption methods), direct combustion methods (Bl high-temperature flame treatment), and (C) catalytic oxidation methods have been attempted, but there are no reports of favorable results.

The problem is that the contained components are extremely small, and at a content of 2 to 20 ppm (1/5 to 500,000) +T'm in a large amount of waste gas, (in the case of the N method, it is difficult to combine with the chemical solution). Due to the contact time, surface area, and low gas partial pressure, sufficient effects were not obtained, and similarly in method (B), the effects were small, and furthermore, due to the increase in fuel costs, sufficient effects were not obtained. (C) method (catalytic oxidation method) Compared to the ijB method, it is possible to obtain the maximum effect at relatively low temperatures (e.g. 300°C); however, the conventional Even with the catalyst method, these objectives could not be achieved.The reason for this is that the amount of these gas components to be treated contained in the exhaust gas is extremely small, and at the same time, the catalyst method used conventionally Whether the carrier is a pellet type or a honeycomb type, it is a parallel flow or semi-parallel flow type as shown in Figure 2, and the minimum 1
It has been found that since each section has a cross-sectional area of approximately 2 square millimeters or more, the gas to be treated passes through without coming into contact with the catalyst, which has a significant impact on treatment performance.

(Problems to be Solved by the Invention) The present invention solves the drawbacks of the conventional method of treating waste gas by catalytically oxidizing cyanide compounds, and reliably catalyzes the extremely small amount of cyanide compounds in the waste gas. The aim is to provide a method for treating waste gas that completely renders it harmless by bringing it into contact with the gas.

(The tth means for solving all the problems) The present invention provides a catalyst filter in which a noble metal catalyst is fully supported on a cloth-like carrier of quartz glass fiber containing 90% or more of silica, and waste gas containing cyanide compounds is injected into the catalyst filter. This is a waste gas processing method characterized by passing the waste gas through the waste gas.

(Function) As shown in Figure 3, for example, a diameter of 5 mm (so
In the case of pellet catalysts (0 microns), many layers of platinum catalyst are deposited in the thickness direction, but because the diameter is large and there are few geometric surfaces, it is difficult to contact all the trace components of the gas at a constant flow rate. It's impossible. Naturally, in order to solve this problem, it is obvious that by reducing the diameter of the knot, the surface area that comes into contact with the cyan gas when powdered is increased. However, in reality, fine powder is 071-7. (There was no container to support it. Therefore, I came up with the idea of forming the fine powder into a fine line. If I could use glass fiber with a diameter of 9 microns to
It has a surface area 170 times larger than that of a four-round pellet with a diameter of 5 mm. Therefore 2-3 pp
Even a very small amount of cyan gas on the order of 2 to 3 millionths of an inch (2 to 3 millionths of an inch) is not allowed to escape and can be brought into contact with the surface of the precious metal catalyst.

(Example) A ninth example of a catalyst filter implementing the present invention is shown in FIG. This catalyst filter is made of silica glass fibers with a diameter of approximately 9μ ((LOO9m)) with a silica content of 90% or more, which has a thickness of α2μ and a catalyst uniformly adhered to the filter.
Gather 0 pieces together to make one thread, weave this thread to make a cloth, and then stack 10 to 20 pieces of this cloth to form a waveform filter as shown in the figure. Compared to the case of using a conventional pellet type catalyst carrier, the geometric surface area is at least 170 times higher, and the cross section of the minimum 1 section where the gas flow is 1 m area 1 d.
It was reduced to less than 1/100th.

In another implementation f'Aj, a platinum catalyst is uniformly coated and supported on the surface of a quartz glass fiber with a diameter of about 9μ to a thickness of α2μ, and a thread is composed of 12,400 fibers of A woven fabric is made of 7,200 quartz glass fibers, one in every five fibers in the length and width, and nine thick threads are woven into the fabric to act as spacers.
A four-ply, corrugated catalyst filter was formed into a double-layered mold, and the outlet side of the element was covered, so that all of the process gas passed through the catalyst filter.

By passing synthetic cyan gas through this catalyst filter, the following results were obtained. The synthetic cyanide gas on the inlet side has a gas concentration of cyanide 24.0 ppm, T, D, engineering 1, 57 ppm.
m, moisture 10%, residual air, introduced into the catalytic filter at 320°C with a space velocity (S, V, value) I
Removal rate at 02 ppm? ? , 9chi, T, D, engineering 0.0
1 ppm, 994% removal result (i-obtained).

In addition, this catalyst filter uses silica glass fiber with a silica content of 90% or more as a carrier, so it is completely impervious to acid gas (8048 ox) coexisting in waste gas.
Never.

(Effects of the Invention) By adopting all of the above-mentioned configurations, the present invention provides a compact catalytic filter that is completely impervious to acidic gas coexisting in the exhaust gas. We have succeeded in completely oxidizing and decomposing even trace amounts of cyanide compounds and rendering them harmless.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a quartz glass fiber catalyst filter used in the present invention, Fig. 2 is a sectional view of a conventional pellet catalyst and a honeycomb catalyst packed together, and Fig. 3 is a comparison of a pellet catalyst, a powder catalyst, and a glass fiber catalyst. It is a conceptual diagram. Sub-agents 1) Meifuku agent Ryo Hagiwara - Sub-agent Atsuo Anzai Figure 1. . Figure 2 7, Eng, t] 6 lies Figure 3

Claims (1)

[Claims] A method for treating waste gas, which comprises passing waste gas containing a cyanide compound through a catalyst filter in which a precious metal catalyst is supported on a cloth-like carrier of quartz glass fiber containing 90% or more of silica.