JPS58146447A - Catalyst regeneration method - Google Patents

Abstract

PURPOSE:To regenerate a granular catalyst deteriorated in activity or changed in reaction characteristics easily and economically in one step without pollution, by grinding the surface of each catalyst grain at normal temp. and normal pressure by a dry method. CONSTITUTION:Catalyst grains deteriorated in activity with poisonous substances or deposits are placed together with abrasive grains preferably having 1mm.- about 1/2 of catalyst grain diameter in a vibrating or rotating vessel. Said catalyst grains are ground on their surfaces by vibrating or rotating the vessel. The treating vessel capable of especially generating 3-dimensional high frequency vibration is higher in grinding speed, and large in effect. As the abrasive material, sand, alumina, metal, metal oxide, etc. are embodied. A regenerated catalyst no inferior in both of catalyst strength and active life, as compared with a fresh catalyst can be obtained by this grinding treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for regenerating a catalyst with reduced activity or a catalyst with changed reaction characteristics in a simple and harmless manner in one step at room temperature and pressure in a dry manner.

An example of the application of this regeneration method is the regeneration of a catalyst used for catalytic cracking of heavy oil whose activity has decreased due to the deposition of coke or sulfur-containing coke. Regeneration of catalysts used in hydrogenation processes such as hydrodesulfurization, hydrocracking, or hydrodemetallization of heavy oil, whose activity has decreased due to the accumulation of metal oxides such as nickel, cobalt, and vanadium. Regeneration of catalysts used for automobile exhaust gas purification whose activity has decreased due to accumulation of phosphorus, lead, etc. Catalysts used for dry denitrification and desulfurization of heavy oil-fired boiler exhaust gas whose reaction characteristics have changed due to the deposition of vanadium compounds or alkali metal compounds (catalysts whose oxidation rate of coexisting sulfur dioxide gas has increased) or whose activity has decreased. Playback. This is to regenerate a catalyst used in a Claus reactor whose activity has decreased due to sulfur precipitation due to the temperature drop during the 7-year down cycle. In addition, it can be widely applied as a method for regenerating a catalyst whose activity has changed depending on the components in the reactant, and is not limited to the above-mentioned usage examples.

Conventionally proposed catalyst regeneration methods include heat treatment (JP-A-55-106547, JP-A-54-2992, etc.) and wet treatment with water and chemicals (JP-A-54-51991).
．． JP-A-56-28644, etc.) Combination of wet treatment and heat treatment (JP-A-54-10294, etc.) Ammonia-containing gas treatment (JP-A-55-51438, JP-A-54-29894)
), gas treatment methods such as chlorination and volatilization removal of deposited metal compounds (Japanese Unexamined Patent Publication No. 101794/1984), and many other methods, but these methods are difficult to use in terms of regeneration efficiency, economic efficiency, and ease of processing operations. There is no known method that is fully satisfactory. Furthermore, although these regeneration methods are individually effective against specific causes of deterioration in catalyst performance, if multiple causes occur, multiple regeneration methods are required.

The present invention is a method for regenerating a catalyst, which is characterized by dryly polishing the surface of a catalyst whose activity has decreased or whose reaction characteristics have changed, at room temperature and pressure, and which can further address multiple causes. It is simple and economical, and it also improves catalyst strength, activity,
In both cases, a regenerated catalyst with a life comparable to that of a new catalyst can be obtained.

The device used for the polishing process is not particularly specified as long as it can polish the surface layer by vibration or rotation, but a device that generates three-dimensional high vibrations has a faster polishing rate and is more effective.

The amount of abrasive to be used may be 10% or more of the voids between the catalysts, but it is particularly effective to coexist preferably 50% or more of the abrasive. The particle size of the abrasive may be from 0.111111 to about the same particle size as the catalyst, but in consideration of separation from the catalyst and catalyst powder after polishing, it is preferably about 1 m+x or about the same particle size as the catalyst. In addition, it is preferable to make the bottom surface of the device a mesh with openings large enough to prevent the abrasive from falling, or to sequentially remove the abrasive powder generated by airflow in a certain direction, in order to increase the effect.

The material of the abrasive used in the present invention may be sand, alumina, etc., as well as metals or metal oxides, and it is more effective if the hardness is moderate.

The present invention will be specifically explained below using examples.

Example 1 A catalyst with changed reaction characteristics was used as the regenerated catalyst.

This catalyst has been used for 1100 hours in dry denitrification equipment for C heavy oil combustion exhaust gas containing 1300 ppm of SOx, and as time passes, vanadium compounds in the heavy oil accumulate in the pores on the surface of the catalyst, and although the denitrification activity is maintained. SO in exhaust gas is a side reaction.

This is a catalyst whose oxidation activity is increasing, and there is concern that if the accumulated amount of vanadium compounds further increases, the harmful effects of S03 produced may be a concern.

The removal rate of the vanadium compound in the catalyst was determined from the amount of V before and after polishing by 4-(2-pyridylazo)-resorcinol spectrophotometry, and the distribution state of vanadium atoms was analyzed by an X-ray microanalyzer. In addition, the SO and oxidation rate of the catalyst were measured by filling a Pyrex tube with an inner diameter of 31 φ and keeping the outside warm with catalyst particles with an apparent volume of 1,637 n/cm, and applying a mixed gas of the following composition for 5 V = 5,000 hr at a catalyst bed temperature of 450 t. The outlet gas after contact was sampled at (room temperature equivalent), and the SO8 concentration was chemically analyzed using the arsenazo method, and the oxidation rate of SO2 was calculated using the following formula.

0 Mixed gas composition No. NH3802H, OO, CCo2N2200p
p 200ppm 1300ppm 10%8% 1
The 2%-old catalyst was spherical with an average diameter of 7.0 μm, and the distribution of vanadium atoms was about 100 μm from the surface layer as shown in FIG. Therefore, since the amount of polishing at this time was 9.3%, the time when the amount of polishing exceeded 9% was considered to be the end of regeneration. Also, SO before playback
2 conversion rate is 51%, v, 0. was 0.08%.

The above-mentioned catalyst 160 with changed reaction characteristics was placed in a vibrating mill manufactured by Tsukishima Kikai (model number 3DM) which gave 9 three-dimensional high vibrations, and sea sand 83Ag (void volume x 10) and operated for 2.5 hours to polish the surface layer. As a result, the distribution of vanadium atoms was the first.
As shown in the figure, the rich surface layer had disappeared. The vanadium content is 0°019% (removal rate 76.3%), and S
The oxidation rate of O was 1.7%, and no difference was observed with the new catalyst (1.5%). Furthermore, as shown in Table 1, physical properties such as crush strength, drop strength, specific surface area, and pore volume were also equivalent to those of the new catalyst.

Table 1 SO before and after regeneration, oxidation rate, and physical properties Example 2 In Example 1, 46 kg of abrasive (void amount x o, 55
) and the time required for polishing by 9% was about 4 hours. (Refer to Figure 2) Reference Example 1 In Example 1, when carried out in the absence of abrasive, 5
The polishing rate at the time point was 3.8% and the activity regeneration rate was about 44%. (See Figure 2) Example 3 At the sulfur recovery plant, due to trouble with the waste heat boiler, the sulfur gas in the Claus reactor was not purged and an emergency shutdown was performed. When the surface of the titania-based Claus catalyst (so-called φ3) which was stuck to the surface and stuck to each other was polished for 2 hours in the same manner as in Example 1, it returned to its original spherical shape and regained the air permeability when packed.

To measure the sulfur recovery rate of the catalyst, catalyst particles with an apparent volume of 20 m/cm were packed into a Pyrex tube with an inner diameter of 20 mm and the outside kept warm, and a mixed gas of the following composition was applied at 5 V at a catalyst bed temperature of 260°C.
= 1600hr1 (room temperature equivalent) The outlet gas was analyzed by gas chromatograph method and the recovery rate was calculated using the following formula. 0 Mixed gas composition H, S 5o2H, ON2 2.45% 122% 25 % Balance The physical properties and yellow recovery rate of the new catalyst before and after regeneration are shown in Table 2.

Table 2 Example 4 In a dry denitrification equipment for natural gas combustion exhaust gas, a catalyst (3IIIlφ) which had lost air permeability due to a large amount of carbon generated due to incomplete combustion covering the catalyst was subjected to surface polishing for 30 minutes according to Example 1. , 2.3 wt% carbon was removed and air permeability was restored. The denitrification activity of the catalyst is the inner diameter of 22
The apparent volume of the Pyrex tube that insulates the outside of the tube is 1.
Filled with 3i catalyst particles, and at a catalyst bed temperature of 290°C, a mixed gas with the following composition was applied for 5V = 15,000 hr (standard conversion)
The change in NOX concentration after contact was calculated using the ml constant linear equation.

Mixed gas composition No NH, O, H, Ori.

200ppm 180ppm 3% 10%
The residual performance was as follows.

Example 5 When 5 kg of the same catalyst and 2.5 kg of sea sand as in Example 1 were placed in an iron cylindrical container with a lid, having a diameter of 250 ft and a depth of 300 am, and aged for 5 hours at a speed of l 20 <pm, the polishing rate was It was 7.4%.

Example 6 An experiment was conducted in the same manner as in Example 5 except that the amount of sea sand in Example 5 was 1.25 kg, and the polishing rate after 5 hours was 2%.

Reference Example 2 When the same procedure as in Example 5 was carried out except that the amount of sea sand was set to zero, the polishing rate after 5 hours was 1.4%.

[Brief explanation of the drawing]

FIG. 1 is a distribution map of vanadium atoms measured by an X-ray microanalyzer before and after catalyst regeneration, and FIG. 2 shows the relationship between regeneration time and polishing rate. Patent applicant Sakai Chemical Industry Co., Ltd. Representative Suhara Nibe

Claims (1)

[Claims] A granular catalyst whose activity has decreased due to poisonous substances or deposits is placed in a vibrating or rotating container together with an abrasive.
A catalyst regeneration method characterized by removing poisonous substances or deposits by surface polishing.