JPS58189042A - Activation of catalyst - Google Patents

Abstract

PURPOSE:To wash and re-activate a catalyst capacity of which is lowered by the accumulation of a poisoning substance, in regenerating a catalyst used in gas treating reaction, by a method wherein the catalyst is washed by an aqueous nitric acid solution and the washed catalyst is dried. CONSTITUTION:When the activity of a catalyst is lowered in reaction for treating an exhaust gas generated through the combustion of coal or petroleum, the flowing of a treating gas is stopped while the catalyst is washed by using an aqueous nitric acid solution as washing water and the washed catalyst is dried. By this method, the pH of a liquid is lowered by the aqueous nitric acid solution to elute not only an alkali component but a component such as a fine calcium compound clogged between fine pores of the catalyst and effective regeneration is carried out to re-activate the catalyst.

Description

[Detailed Description of the Invention] The present invention provides an improved method for cleaning and reactivating the catalyst when its performance deteriorates due to the accumulation of poisonous substances during use, especially when the catalyst is used for combustion of coal or Ishiura. Suitable for application to denitrification reactions in which exhaust gas is passed through a catalyst to reduce nitrogen oxides in the exhaust gases to render them harmless, or reactions in which carbon monoxide or hydrocarbons are oxidized and burned using a catalyst. It is something.

In general, those that treat the exhaust gases of Ichiura-fired boilers and coal-fired boilers, including t4 tast and SOx;・Optimal considering wearability
It is necessary to select a suitable catalyst fI, and instead of A120g, which is widely used in LNG-fired boilers and other applications, Ti
By using O2 as a carrier, SOx resistance can be improved for 1 minute.
Ko and Kara, T i 02 iC V2 0II, W
Oa, F e203.

Catalysts carrying a compressible component such as Moss f are used. Catalyst shapes that are good at blocking dust include granules, circles, solids, etc. A method of using a moving bed of catalysts, machine shapes, hype shapes, square shapes, honeycomb shapes, etc. IJ1 sludge was made into a fixed bed using the catalyst structure of
Comparative test of how to pass through i+ style. and current (1-C
is the most economical and easy to maintain. A grade 1'-type catalyst or I flow 6- and coal-fired boiler 1::
For the denitrification reaction on the task side, a hard catalyst (R09) has been developed, and the real III is in a very good condition.

However, even with a parallel flow R-shaped catalyst using TiO2 as a carrier, dust may adhere to the catalyst surface and get wet, or dust-laden steam in the furnace may occur due to damage to the boiler evaporator pipe or economizer water supply pipe. Or when wetting the catalyst with water,
Since the above-mentioned task contains Na, Mg, etc., poisonous substances such as Na=Mg rapidly increase inside the catalyst, resulting in an irresistible performance deterioration and boiler failure. Sometimes accidents occur that make it impossible to drive.

If the denitrification equipment loses its performance due to an emergency accident like this, in the worst case scenario, the boiler may have to be shut down, so performance can be restored in a short period of time. Is it necessary to provide a method?

The name of the present invention is ``During the operation of a gas treatment device containing a built-in catalyst that flows through the waste passage, an 11.5-pressure gas is injected from a suit-pro nozzle to remove sludge and deposits on the catalyst layer. After removing the dust, stop the operation of the device.1. Next, replace the soon blow nozzle with a nozzle for water a, and inject cleaning water from the washing nozzle to remove the dirt that has entered and accumulated inside the catalyst. The addition of a catalyst, which consists of eluting and removing poison! components, is also a force method (Patent application 12883/1983
No. 0).

□゛1/1 capacity t+('F
Sometimes, when the catalyst is washed with water to recover the catalyst performance with the catalyst packed inside the device, after stopping the flow of the treated scum, the washing water is poured into the cross section of the empty column 1-1200 where the scum passes through.
1.2 or more times at a rate of ~800e/min. I) is M
The catalyst activation saw method (Japanese Patent Application No. 56-[2883]) is characterized in that the catalyst layer gas passage surface is divided into a plurality of parts and sequentially washed with water, and at that time, the first IJ) Discard one shot of water and use the subsequent wastewater with a low concentration of dyeing substances as water for washing the second catalyst section, and repeat the same steps as above. ``Catalyst washing power method characterized by washing with water'' (patented)
1984-117843 shi;) etc. 1 Invented a method for revitalizing mountains by washing with water and applied for a patent.

All of these inventions are effective as a means for reactivating a catalyst whose performance has deteriorated as described above, or because the exhaust gas also contains Ca, SOx, and H2O, Poisonous substances that are difficult to dissolve in water, such as calcium sulfate, may accumulate on the surface or inside of various catalysts (including granular catalysts and catalysts made of carriers or A1.03).
In such cases, cleaning with water alone will destroy the catalyst.
It is difficult to reactivate the ability to a usable state. In addition, crystals of sulfuric acid may be deposited on the surface of the catalyst after washing with water, and if the pores of the catalyst are blocked, water-soluble coatings such as Na may accumulate inside the pores. This also prevents the elution of toxic substances.

The present invention was invented in an attempt to improve the insufficiency of the reactivation method by washing the catalyst with water, which has been proposed under the above title and some of which has already been practiced.

This cleaning method uses a nitric acid aqueous solution to raise the pH of the solution, and elutes not only the alkaline components, but also components that are difficult to elute in a water tank, such as lu/um compounds, from the fine particles clogged between the catalyst pores. It also becomes IIJ ability, and can perform the effective Song-like IS. A nitric acid compound is often used as a raw material for the catalytic active component, and nitric acid is completely harmless to the catalyst, so its solution can be used even at 4°C. However, the concentration in the present invention is not particularly limited.

The combustion exhaust gas that produces dust usually contains sulfur oxides (S
Considering the SOx resistance, the catalyst carrier that can be applied to this exhaust gas is TiO2, Zr rather than Al2O8.
02f= is preferable, and the present invention also describes a regeneration method for a catalyst containing TiO2 as one component.

However, in the method of the present invention, if the performance is degraded due to dust in the combustion exhaust gas, it is possible to adjust the catalyst composition and shape to overcome fI+1.

Furthermore, depending on the manufacturing method, are there any types of nicam catalysts, such as one in which the catalyst is divided into honeycomb shapes, and one in which the catalyst components are coated and supported on a fire-resistant honeycomb-shaped aggregate such as mullite or corn nyllite? Needless to say, it can be applied to either case.

The present invention will be explained below with reference to Examples.

Figure 1 shows the relationship between the NHa/NOx ratio and the denitrification rate under the same activity measurement conditions for a honeycomb-shaped catalyst for Ura Toma waste sludge, where a is FRE and /.

Catalyst, b is a catalyst with reduced performance, C is a catalyst with reduced performance immersed in 5 times its volume of water for 60 minutes, washed and dried, d is a catalyst with reduced performance in an N/100 nitric acid aqueous solution 5 times its volume with M That of the catalyst soaked in and dried. It can be seen that by immersing it in a nitric acid aqueous solution, the performance almost recovered to that of Fresonoyu.

Figure 2 shows NHa/NOx under the same activity measurement conditions for a honeycomb-shaped catalyst for coal-fired waste as in Figure 1.
There is a relationship between the ratio and the denitrification rate, where a is the Freno Noyu catalyst, b is the catalyst with decreased performance, C is the catalyst that has been soaked in 5 times the volume of water of the catalyst with decreased performance, washed and dried, and d is the catalyst with decreased performance. This is the catalyst that was immersed in the same volume of 5-position N/+00 nitric acid aqueous solution for 60 minutes and dried. In this case as well, the effect of the nitric acid aqueous solution is clear.

11 The present invention has been explained with reference to examples, but cleaning with nitric acid aqueous solution has a very large rJr production effect, and u4
'I Is it possible to extend the catalyst life through repeated use?IIJ
From the capacity and l, the catalyst cost in the denitration equipment is 1 + f
; I'm hoping for a reduction.

Although the present invention has been described in detail above as an example in which the present invention is applied to a fixed body honeycomb catalyst, the present invention can also be implemented in the same manner when a moving bed type granular catalyst is extracted from a catalytic reaction apparatus and treated. If you use an aqueous nitric acid solution as a cleaning solution once a month, you can omit the final cleaning step with water, but when using an activation catalyst, the nitrate remaining in the catalyst will easily decompose at the temperature of the waste residue, so the catalyst will be activated. The effect is full),

[Brief explanation of the drawing]

Fig. 1 shows the catalyst performance of a honeycomb-shaped catalyst for Ura-fired waste residue, and Fig. 2 shows the catalytic performance of a honeycomb-shaped catalyst for coal-fired waste residue obtained by regenerating an actual product with degraded performance. Ken 1 figure” HvNOx (Oshiru ratio)

Claims (1)

[Claims] When the catalyst performance deteriorates in the scum treatment reaction, the catalyst is washed to restore the catalyst performance, and after stopping the flow of the processing gas, the catalyst is washed with an aqueous nitric acid solution, and the washed catalyst is further dried. A method for activating a catalyst characterized by: