CN1120051C

CN1120051C - Catalyst regeneration process

Info

Publication number: CN1120051C
Application number: CN 00110718
Authority: CN
Inventors: 张喜文; 孙万付; 赵长治; 张淑梅; 王少军
Original assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Current assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Priority date: 2000-07-24
Filing date: 2000-07-24
Publication date: 2003-09-03
Anticipated expiration: 2020-07-24
Also published as: CN1335202A

Abstract

The present invention discloses a used method for the regeneration of catalysts. Catalysts are regenerated through regenerative processes of a two-step method. The two-step method comprises: step one, the catalysts are reduced to make sulphur reacting with active metal converted to hydrogen sulphide, and then, the hydrogen sulphide escapes; step two, the catalysts are oxidized, and coke is eliminated. The catalysts regenerated by the combination of the two steps can greatly reduce the generation of SO4<-2> on the catalysts, so that the present invention is favourable for the activity of the catalysts and avoids the corrosion of a regenerator.

Description

Catalyst regeneration method

The present invention relates to a process for regenerating used catalysts, in particular petroleum refining catalysts, and in particular hydrofinishing and hydrocracking catalysts.

Catalytic processes, such as cracking, refining, and reforming, are commonly employed in petroleum refining processes to economically treat feedstocks and convert them into various useful end products. Catalysts are critical to the completion of these processes. For most commercial catalysts, long run-time results in a gradual decline in its activity or selectivity, i.e., catalyst deactivation. The reasons for the deactivation of the catalyst are complex and different people can classify the catalyst from different angles, but the general idea is that in the catalytic reaction in which organic matters participate, coking is the most common and important one of the causes of deactivation. The coking is a reversible reaction process, i.e. the coke deposited on the catalyst can be removed by oxidizing and burning under certain thermodynamic conditions. Therefore, the industry often regenerates the deactivated catalyst by means of oxidative scorching, in order to restore the activity of the catalyst, for example,the method of patent US4,007,131, etc., which is to remove the coke on the catalyst in an oxygen-containing atmosphere to restore the activity of the catalyst. Of course, in addition to the coke burning in the regeneration process, other components on the catalyst are necessarily contacted with the regeneration gas and even act to influence the properties of the catalyst, so that the physicochemical properties of the regenerated catalyst and the fresh catalyst are relatively close to each other as far as possible during regeneration.

The coke in the deactivated catalyst, which also contains impurities such as nitrogen, sulfur, oxygen, etc., is inevitably converted to their respective oxides and removed from the catalyst during regeneration as shown in the following formula:

in the presence of oxygen, the sulfur dioxide produced will be readily oxidized to sulfur trioxide:

the sulfur trioxide will interact with the catalyst support or alumina of one of the supports to produce aluminum sulfate or react with the active metal on the catalyst to produce sulfate:

meanwhile, if water is still present in the regeneration atmosphere, the generated sulfur dioxide and sulfur trioxide may be converted into sulfurous acid and sulfuric acid, and then react with alumina or active metal in oxidation state on the catalyst.

SO produced by the above process₄ ^2-The negative impact on catalyst activity is evident: on the one hand,it weakens the catalytic action of the active metal and on the other hand, changes many physicochemical properties of the carrier, SO that strict control of SO is required during the regeneration of the catalyst₄ ^2-And (4) generating.

It is well known that some petroleum refining processes, such as hydrorefining, hydrocracking, etc., typically employ supported metal catalysts which are comprised of an active metal which provides hydrogenation properties and a support which provides an acid function, these catalysts often being maximally active only when the active metal is in the sulfided state, and which have been subjected to a sulfiding process prior to use, so that the deactivated catalyst, the active metal, is present in the sulfided form. These sulfided metals will generate significant amounts of sulfur dioxide during the transition to the oxidation state upon regeneration of the catalyst, thereby mimicking the aboveFormation of SO₄ ^2-Of the SO produced in the process₄ ^2-SO produced by sulfur contained in coke₄ ^2-More, the poisoning effect on the catalyst is stronger.

In addition, a large amount of heat is generated during the conversion of the sulfided metal to the oxidized metal on the catalyst, and therefore the temperature of the regeneration bed must be strictly controlled to prevent sintering of the catalyst due to too rapid a temperature rise. For this reason, the patent US5,015,611 states that for hydrotreating catalysts, before the combustion of the sulfur poison, a certain amount of water may be brought into contact with the catalyst, which is advantageous for the catalyst bed temperatureBut the drawback of this solution is obvious, namely the intangible increase of SO on the catalyst₄ ^2-The probability of generation.

Accordingly, it is an object of the present invention to provide a method for regenerating a used catalyst, which can prevent the generation of harmful SO from metal sulfides on the surface of the catalyst during regeneration₄ ^2-Meanwhile, the temperature is easier to control when the vulcanized metal is converted into the oxidized metal, so that the performance of the regenerated catalyst is better recovered.

The method comprises the following steps:

1) contacting the deactivated catalyst with a hydrogen-containing gas at an elevated temperature to convert sulfided metal on the catalyst to reduced metal and to convert sulfur in the catalyst to hydrogen sulfide for removal, and during which at least a portion of the coke is removed;

2) oxidizing the catalyst treated in the step 1) to convert the metal components on the catalyst into an oxidized state, and removing coke to recover the activity of the catalyst.

The specific operation process in the step 1) may be: the catalyst is reduced in an atmosphere containing hydrogen in the range of 3 to 30 v%, preferably 10 to 20 v%, at a temperature of 200 ℃ to 350 ℃, preferably 250 ℃ to 300 ℃ for at least 2 hours, preferably 2 to 5 hours, preferably 3 to 4 hours, and is cooled to room temperature while maintaining the original atmosphere.

The specific operation process in the step 2) may be: the entire system was initially purged with inert gas until the concentration of hydrogen in the purged gas was no greater than 0.2 v%, and then the atmosphere was switched to an oxygen-containing gas. The oxygen content introduced at the beginning is strictly controlled to be less than 0.1 v%, preferably less than 0.05 v%, and the purging is continued for 2 hours or more, preferably 2 to 4 hours. Subsequently, the oxygen content may be gradually increased to 0.5-2.0 v%, preferably 1.0-1.5 v%, and the catalyst may be subjected to stepwise charking regeneration. The main control steps are as follows: keeping the temperature at 250 ℃ at 220 ℃ and preferably at 240 ℃ for at least 2 hours, preferably 2-6 hours; keeping the temperature at 350 ℃ and preferably at 310 ℃ and 280 ℃ for at least 1 hour, preferably 1-4 hours; the temperature is maintained at 480 ℃ and 550 ℃, preferably 490 ℃ and 510 ℃ for at least 2 hours, preferably 2-4 hours.

The regeneration process of the present invention is particularly suitable for hydrogenation catalysts, especially for catalysts which have to be sulfided before use. These catalysts generally comprise a metal component selected from groups VIB, VIIB, VIII and are supported on alumina, or alumina with other supports such as silica, alumina silicates, zeolites, etc. The catalyst is generally cylindrical, spherical or multi-lobed in shape, having a diameter of 0.5 to 3.5 mm and a length of 1.5 to 10.0 mm.

In the present invention, the deactivated catalyst is placed in a reactor having any suitable configuration. Except the indicated hydrogen or oxygen, the used atmosphere adopts inert gases such as nitrogen or argon, and the purity is more than 99.99 v%.

It should be noted that, particularly at the constant temperature in step 2), the bed temperature of the catalyst is controlled as much as possible to prevent the catalyst from sintering due to too rapid temperature increase.

Compared with the prior art, the method provided by the invention regenerates the catalyst through a two-step regeneration process. The first step is the reduction of the catalyst, which converts the sulfur reacting with the active metal into hydrogen sulfide to escape, and the second step is the oxidation of the catalyst and the removal of coke. The combination of the two steps with the regenerated catalyst can greatly reduce SO on the catalyst₄ ^2-While the temperature is more easily controlled when the sulfided metal is converted to the oxidized state, therebyBeneficial to the activity of the catalyst and avoids the corrosion of the regeneration device.

The process of the invention is further illustrated by the following examples.

Example 1

MoNiP/Al with properties shown in table I₂O₃Hydrotreating catalyst containing 15 v% H at 300 deg.C₂/N₂After reducing for 4 hours in the atmosphere, the original atmosphere is kept to be cooled to the room temperature. Followed by N₂The entire system was purged for 3 hours and then the atmosphere was switched to O containing 0.03 v% oxygen₂/N₂Purging was continued for 3 hours. Subsequently, the catalyst was subjected to stepwise charking regeneration with a stepwise increase in the oxygen content of the atmosphere to 1.5 v%.The main temperature control steps are as follows: the temperature is kept constant for 4 hours at 240 ℃, 3 hours at 300 ℃ and 4 hours at 500 ℃ to complete the regeneration process of the catalyst. The results are shown in Table I.

TABLE comparison of Properties before and after regeneration of a deactivated hydroprocessing catalyst

Deactivated catalyst regenerated catalyst comparative catalyst analysis method MoO₃W% 21.5021.4321.47 inorganic assay NiO, w% 3.823.583.62 inorganic assay P₂O₅W% 3.013.032.98 inorganic assay C, w% 2.090.150.20 chromatography S, w% 8.410.231.08 chromatography

Meanwhile, the catalyst contains 1.5 v% of oxygen O directly in the atmosphere₂/N₂The results of the regeneration of the comparative catalyst, which were carried out at 120 ℃ for 2 hours, at 240 ℃ for 4 hours, at 300 ℃ for 3 hours and at 500 ℃ for 4 hours, are also shown in Table I. X-ray photoelectron spectroscopy shows that S on the regenerated catalyst and the comparative catalyst are SO₄ ^2-The existence of the catalyst indicates that the invention has better prevention of the generation of SO in the regeneration process of the catalyst₄ ^2-The function of (1).

Example 2

MoNiP/USY + Al with properties shown in table II₂O₃(containing USY43 w%) hydrocracking catalyst containing 15 v% H at 280 deg.C₂/N₂Reducing the mixture in the atmosphere for 3 hours, and then keeping the original atmosphere to be cooled to room temperature. Followed by N₂The entire system was purged for 2 hours and then the atmosphere was switched to O containing 0.03 v% oxygen₂/N₂For 2 hours. Subsequently, the catalyst was subjected to stepwise charking regeneration with a stepwise increase in the oxygen content of the atmosphere to 1.0 v%. The main temperature control steps are as follows: the temperature is kept constant at 240 ℃ for 3 hours, at 300 ℃ for 2 hours and at 500 ℃ for 3 hours, thus completing the regeneration process of the catalyst. The results are shown in Table II.

TABLE comparison of the Properties before and after regeneration of a deactivated cracking catalyst

Deactivated catalyst regenerated catalyst comparative catalyst analysis method MoO₃W% 19.2719.1318.68 inorganic assay NiO, w% 5.615.475.36 inorganic assay P₂O₅W% 1.481.431.56 inorganic assay C, w% 3.970.200.28 chromatography S, w% 7.650.181.29 chromatography

At the same time, the catalyst is directly in the presence of 1.5% by volume of oxygen-containing O₂/N₂The results of comparative catalyst regeneration performed in an atmosphere of 120 ℃ for 2 hours, 240 ℃ for 3 hours, 300 ℃ for 2 hours and 500 ℃ for 3 hours are also shown in Table II. X-ray photoelectron spectroscopy shows that S on the regenerated catalyst and the comparative catalyst are SO₄ ^2-The existence of the second table shows that the invention has better prevention of relapseFormation of SO on the catalyst during the course of production₄ ^2-The ability of the cell to perform.

Claims

1. A method of regenerating a catalyst comprising:

2) oxidizing the catalyst treated in the step 1) to convert metal components on the catalyst into an oxidation state, and removing coke to recover the activity of the catalyst; the catalyst is a supported hydrogenation catalyst with active metal components selected from VIB, VIIB and VIII groups.

2. The method for regenerating a catalyst according to claim 1, wherein the specific operation in step 1) is: the catalyst is reduced for at least 2 hours in an atmosphere containing 3-30 v% of hydrogen at the temperature of 200-350 ℃, and the original atmosphere is kept to be reduced to the room temperature.

3. The method for regenerating a catalyst according to claim 1, wherein the specific operation in the step 2) is: purging the whole system by usinginert gas until the concentration of hydrogen in the purged gas is not more than 0.2 v%, and then switching the atmosphere to oxygen-containing gas; the oxygen content introduced at the beginning is less than 0.1 v%, and the duration is at least 2 hours; then, the oxygen content can be gradually increased to 0.5-2.0 v%, and the catalyst is subjected to step-by-step charcoal-burning regeneration; the main control steps are as follows: the temperature is constant at 250 ℃ for 2-6 hours at 220-.

4. The method for regenerating a catalyst according to claim 1, wherein the specific operation in step 1) is: the catalyst is reduced for 2 to 5 hours in an atmosphere containing 10 to 20v percent of hydrogen at the temperature of 250 ℃ and 300 ℃, and then the original atmosphere is kept to be cooled to the room temperature.

5. The method for regenerating a catalyst according to claim 1, wherein the specific operation in the step 2) is: purging the whole system by using inert gas until the concentration of hydrogen in the purged gas is not more than 0.2 v%, and then switching the atmosphere to oxygen-containing gas; the oxygen content introduced at the beginning is less than 0.05 v%, and the duration is 2-4 hours; then, the oxygen content can be gradually increased to 1.0-1.5 v%, and the catalyst is subjected to step-by-step charcoal-burning regeneration; the main control steps are as follows: keeping the temperature at 230 ℃ and 240 ℃ for 2-6 hours; the temperature is kept constant at 290 ℃ and 310 ℃ for 1-4 hours, and at 490 ℃ and 510 ℃ for 2-4 hours.