阅读说明：本技术 一种固定床费托合成钌基催化剂的原位再生方法 (In-situ regeneration method for ruthenium-based catalyst synthesized by Fischer-Tropsch fixed bed ) 是由 周建强 燕来 黄礼春 索海云 郜文斌 王缠和 李国强 杨勇 于 2020-06-11 设计创作，主要内容包括：本发明提供了一种固定床费托合成钌基催化剂的原位再生方法,所述方法包括：(1)使用处于亚临界状态的石脑油对待再生的费托合成钌基催化剂进行处理；(2)使用非活性气体对石脑油处理后的催化剂进行吹扫；(3)使用含氧气体对吹扫后的催化剂进行氧化；以及(4)对氧化后的催化剂进行氢还原,得到再生后的费托合成钌基催化剂。通过本发明提供的原位再生方法可以对固定床费托合成钌基催化剂实现原位再生,该再生过程操作简便易于实现,所用材料及试剂价格廉价。该方法消除了因积碳、金属相变和部分毒物污染造成的催化剂失活,从而达到延长费托合成钌基催化剂寿命的目的。(The invention provides an in-situ regeneration method of a ruthenium-based catalyst synthesized by a fixed bed Fischer-Tropsch process, which comprises the following steps: (1) treating the Fischer-Tropsch synthesis ruthenium-based catalyst to be regenerated by using naphtha in a subcritical state; (2) purging the catalyst after naphtha treatment by using inactive gas; (3) oxidizing the purged catalyst with an oxygen-containing gas; and (4) carrying out hydrogen reduction on the oxidized catalyst to obtain the regenerated Fischer-Tropsch synthesis ruthenium-based catalyst. The in-situ regeneration method provided by the invention can realize in-situ regeneration of the ruthenium-based catalyst synthesized by the Fischer-Tropsch fixed bed, the regeneration process is simple and convenient to operate and easy to realize, and the used materials and reagents are low in price. The method eliminates the catalyst deactivation caused by carbon deposition, metal phase change and partial poison pollution, thereby achieving the purpose of prolonging the service life of the Fischer-Tropsch synthesis ruthenium-based catalyst.)

1. A method for in situ regeneration of a fixed bed fischer-tropsch synthesized ruthenium-based catalyst, the method comprising:

(1) soaking and washing a ruthenium-based catalyst to be regenerated in a fixed bed reactor by using naphtha in a subcritical state;

(2) purging the soaked and washed ruthenium-based catalyst by using inactive gas;

(3) oxidizing the purged ruthenium-based catalyst with an oxygen-containing gas; and

(4) and carrying out hydrogen reduction on the oxidized ruthenium-based catalyst to obtain a regenerated ruthenium-based catalyst.

2. The process of claim 1, wherein the ruthenium-based catalyst is selected from the group consisting of a supported fischer-tropsch synthesis ruthenium-based catalyst; preferably, the loading range of ruthenium in the ruthenium-based catalyst is 0.2-10% by mass; more preferably, for the supported ruthenium-based catalyst for Fischer-Tropsch synthesis, the carrier of the catalyst is selected from alumina, silica, titania or a silicon-aluminum composite carrier, and the specific surface area of the carrier ranges from 70 cm to 500cm²/g。

3. The method according to claim 1 or 2, wherein the temperature in the subcritical state is between 150 ℃ and 350 ℃, preferably between 200 ℃ and 300 ℃; the pressure in the subcritical state is 1.5 to 3.0MPa, preferably 2.0 to 2.5 MPa.

4. The method according to any one of claims 1 to 3, wherein in the step (1), the liquid space velocity of the subcritical naphtha is 0.1 to 5h^-1Preferably 0.5 to 1 hour^-1More preferably 0.5 to 0.8 hour^-1。

5. The method according to any one of claims 1 to 4, wherein in step (2) the non-reactive gas is selected from nitrogen, argon, helium or a combination thereof, preferably nitrogen.

6. The method according to any one of claims 1 to 5, wherein in step (2), the temperature at which the inert gas is purged is 200 to 400 ℃, preferably 250 to 350 ℃; the pressure is 0.1-3 MPa, preferably 2-3 MPa; GHSV of 2000-6000 h^-1Preferably 3000-5000 h^-1(ii) a The time is 0.5 to 2 hours, preferably 1 hour.

7. The process according to any one of claims 1 to 6, wherein in step (3) the oxygen-containing gas is oxygen, air, heliox or a combination thereof, preferably air.

8. The process according to any one of claims 1 to 7, wherein in step (3), the temperature of oxidation is 300 to 500 ℃, preferably 350 to 450 ℃; the pressure is 0.5-2 MPa, preferably 1-1.5 MPa; GHSV of 2000-6000 h^-1Preferably 3000-5000 h^-1(ii) a The time is 0.5 to 2 hours, preferably 1 hour.

9. The method according to any one of claims 1 to 8, wherein, in step (4), the volume fraction of hydrogen gas used in the hydrogen reduction is not less than 99%.

10. The method of any one of claims 1-9, wherein in step (4), the hydrogen reduction conditions are: atmospheric pressureThe temperature is 250-450 ℃, and preferably 300-400 ℃; GHSV of 500-6000 h^-1Preferably 1000 to 2000 hours^-1(ii) a Reducing for 2-12 h, preferably 4-8 h at constant temperature.

Technical Field

The invention relates to an in-situ regeneration method of a ruthenium-based catalyst synthesized by a fixed bed Fischer-Tropsch process, belonging to the technical field of catalysts.

Background

The Fischer-Tropsch synthesis (FTS) process is carried out by mixing synthesis gas (carbon monoxide (CO) and hydrogen (H)₂) Mixed gas of (2) into liquid hydrocarbons or hydrocarbons, is one of the most important ways for the efficient conversion and utilization of non-petroleum carbon-containing resources (natural gas, coal, residual oil, biomass, etc.). In the Fischer-Tropsch synthesis process, synthesis gas is used as a primary product under the action of a catalyst to generate a series of hydrocarbons (C1-C200) with different carbon numbers, wherein the primary product is straight-chain paraffin, and some low-carbon olefins and alcohols are obtained at the same time. The initial product is further treated (such as separation, hydrocracking or hydroisomerization) to obtain oil fuels of gasoline, diesel oil and the like and chemicals of ethylene, propylene, lubricating oil, paraffin and the like with certain specifications.

The catalyst is one of the key Fischer-Tropsch synthesis technologies, and the catalysts used in the Fischer-Tropsch synthesis industry at present mainly comprise an iron-based catalyst and a cobalt-based catalyst. The iron-based catalyst is an early catalyst used in the Fischer-Tropsch synthesis industry, has the advantages of high catalytic activity and low cost, and also has higher water gas shift reaction performancePoor structural stability of the catalyst and short service life. Compared with an iron-based catalyst, the cobalt-based catalyst has the advantages of high CO hydrogenation activity, strong chain growth capacity, difficult carbon deposition and inactivation of the catalyst, less low-carbon olefin and oxygen-containing compound generated in the product, and methane (CH)₄) The catalyst has the advantages of low selectivity, low water gas shift activity, mild reaction conditions and the like, and therefore, the catalyst becomes one of the most promising catalysts for Fischer-Tropsch synthesis. Compared with a cobalt-based catalyst, the ruthenium-based catalyst has the advantages of low loading capacity, higher activity, lower methane selectivity, longer service life, capability of maintaining higher conversion rate in higher water partial pressure and oxygen-containing compound atmosphere and the like, has excellent Fischer-Tropsch synthesis activity and chain growth capability, but has few ruthenium sources and high price, and has the technical problem of overhigh cost when being used for the Fischer-Tropsch synthesis catalyst.

In the Fischer-Tropsch synthesis process, the catalysts have certain service life, and the catalytic activity and the selectivity of required products of the catalysts are gradually reduced in normal use, so that the performance of the catalysts is reduced. The reasons for the performance degradation of the catalyst mainly include the pollution of the catalyst by poisons, carbon deposition of the catalyst, sintering of the catalyst, phase change of active metals, change of the structure of the catalyst and the like. The deactivated or partially deactivated catalyst can restore or partially restore the original catalytic performance through regeneration treatment, so that the service life of the catalyst is prolonged and the catalyst circulation cost is reduced through a proper catalyst treatment or regeneration process, and the method has important industrial significance. Especially for the ruthenium-based catalyst with high price, the catalyst treatment or regeneration process can greatly reduce the usage amount of the fresh ruthenium-based catalyst, thereby saving the cost.

For the catalyst treatment or regeneration process in the art, for example, patent document US5283216 discloses a method for restoring the activity of a hydrocarbon synthesis catalyst by reducing the catalyst with hydrogen in the presence of liquid hydrocarbons at a temperature and pressure at which at least 80% of the original activity can be restored. However, this method of hydrogen re-reduction has certain limitations, which is only effective for catalysts deactivated by active metal phase transition, and cannot solve the problem of catalyst deactivation caused by carbon deposition.

Patent document CN100398501C proposes a method for regenerating a fischer-tropsch slurry bed catalyst to prolong the service life of the catalyst, which mainly comprises the steps of removing hydrocarbons adsorbed by the catalyst, impregnating with a solution, oxidizing, and reducing hydrogen. Although the method for regenerating the catalyst in the patent has a certain effect on the catalyst inactivated for various reasons, the method can damage the structure of the catalyst, influence the interaction between the active metal and the carrier and the interaction between the active metal and the auxiliary agent, and has complex process operation, and the regeneration of the catalyst needs to transfer the catalyst out of the hydrogenation reactor, perform the catalyst in other special equipment and finally return the catalyst to the hydrogenation reactor.

The two catalyst regeneration methods cannot give consideration to the three methods of in-situ, good effect and simplicity and feasibility. Patent document CN1230467A discloses regenerating an in-situ deactivated catalyst in a subcritical or supercritical state by using a part of light oil fraction in a fischer-tropsch synthesis product, and then reducing the treated catalyst with a reducing gas. The method is simple and easy to implement, and the obtained catalyst has good stability and higher activity, but is only limited to Fe catalysts.

Therefore, there is still a need in the art for a method for effectively regenerating a ruthenium-based catalyst in situ by fischer-tropsch synthesis, so as to prolong the service life of the ruthenium-based catalyst and reduce the cost consumption.

Disclosure of Invention

Aiming at the technical problem, the invention provides an in-situ regeneration method of a fixed bed Fischer-Tropsch synthesis ruthenium-based catalyst, which comprises the following steps:

(1) soaking and washing a Fischer-Tropsch synthesis ruthenium-based catalyst to be regenerated in a fixed bed reactor by using naphtha in a subcritical state;

(2) purging the treated ruthenium-based catalyst by using inactive gas;

(3) oxidizing the purged ruthenium-based catalyst with an oxygen-containing gas; and

(4) and carrying out hydrogen reduction on the oxidized ruthenium-based catalyst to obtain a regenerated ruthenium-based catalyst.

Advantageous effects

In the conventional ruthenium-based catalyst regeneration method, the purpose of ruthenium-based catalyst regeneration is to eliminate catalyst deactivation caused by carbon deposition, metal phase transition and partial poison pollution, but long-chain products blocking a pore channel cannot be completely removed. In the present invention, by using naphtha in a subcritical state, long-chain products in the pore channels of the ruthenium-based catalyst can be effectively removed compared to other mineral spirits (e.g., aromatic hydrocarbon solvents, alkane solvents, etc.) under conventional processing conditions, so that the pore structure of the regenerated ruthenium-based catalyst is close to that of a fresh ruthenium-based catalyst.

Compared with the traditional catalyst regeneration method, the in-situ regeneration method for the ruthenium-based Fischer-Tropsch synthesis catalyst of the fixed bed does not need an additional purging process before naphtha treatment, and the naphtha can be directly adopted to treat the ruthenium-based Fischer-Tropsch synthesis catalyst to be regenerated. The in-situ regeneration method has simple process, and the fixed bed Fischer-Tropsch synthesized ruthenium-based catalyst is regenerated, so that the service life of the catalyst is greatly prolonged, the use amount of the fresh ruthenium-based catalyst is reduced, and the operation cost is saved.

Detailed Description

The invention provides an in-situ regeneration method of a ruthenium-based catalyst synthesized by a fixed bed Fischer-Tropsch process. The in-situ regeneration method of the fixed bed Fischer-Tropsch synthesis ruthenium-based catalyst provided by the invention comprises the following steps:

(1) soaking and washing a Fischer-Tropsch synthesis ruthenium-based catalyst to be regenerated in a fixed bed reactor by using naphtha in a subcritical state;

(2) purging the treated ruthenium-based catalyst by using inactive gas;

(3) oxidizing the purged ruthenium-based catalyst with an oxygen-containing gas; and

(4) and carrying out hydrogen reduction on the oxidized ruthenium-based catalyst to obtain a regenerated ruthenium-based catalyst.

In the method, the ruthenium-based catalyst refers to a ruthenium-based Fischer-Tropsch synthesis catalyst filled in a fixed bed reactor. In the present invention, the terms "fixed bed fischer-tropsch synthesis ruthenium-based catalyst", "fischer-tropsch synthesis ruthenium-based catalyst" and "ruthenium-based catalyst" are used interchangeably herein. In the process of the present invention, the pressures employed are gauge pressures, unless otherwise specifically indicated. Further, in the method of the present invention, the atmospheric pressure means one atmospheric pressure.

In a preferred embodiment, the ruthenium-based catalyst may be selected from supported ruthenium-based catalysts. In some embodiments, the support of the ruthenium-based catalyst can be selected from alumina, silica, titania, or a silica-alumina composite support.

The ruthenium-based catalyst before regeneration has a ruthenium loading range of 0.2 to 10% by mass. The specific surface area of the carrier is 70-500 cm²(ii) in terms of/g. In the present invention, ruthenium-based catalysts commercially available in the art can be used as the ruthenium-based catalyst.

In the invention, the fixed bed reactor is a tubular reactor, 500-10000 or more than 10000 reaction tubes are arranged in the reactor, the diameter of each reaction tube is 20-60 mm, preferably 25-50 mm, and the length is 4-15 m, preferably 6-12 m. The catalyst is uniformly filled in each reaction tube. The particle size (diameter) of the catalyst is 0.5-5 mm, preferably 1-3 mm, and the catalyst can be in the shape of column, sphere, hollow sphere, ring, saddle, trilobe, tetralobal and the like.

In the invention, naphtha is light oil for chemical raw materials, which is produced by processing crude oil or other raw materials, and the main component of the naphtha is C5-C12 alkane components. In the present invention, the naphtha used in the step (1) has a C8-C12 alkane content of 40-80 wt% and a sulfur content of not more than 100 ppm.

In the step (1), naphtha is heated and pressurized to a subcritical state before treating the ruthenium-based catalyst to be regenerated with the naphtha. In some embodiments, the naphtha in the subcritical state is at the following conditions: the temperature is 150-350 ℃, and the optimal temperature is 200-300 ℃; the pressure is 1.5 to 3.0MPa, preferably 2.0 to 2.5 MPa. The naphtha under the subcritical state can effectively remove long-chain products in the ruthenium-based catalyst pore channel, particularly heavy alkane, olefin and the like with the carbon number of more than 60, and the long-chain products are accumulated for a long time to cause pore channel blockage and reduce the catalytic efficiency. Reacting naphtha in subcritical state from fixed bed on which ruthenium-based catalyst to be regenerated is locatedInjecting from the top of the reactor, wherein the liquid airspeed is 0.1-5 h^-1Preferably 0.5 to 1 hour^-1More preferably 0.5 to 0.8 hour^-1. In the soaking and washing process, the ruthenium-based catalyst is treated under the condition that the temperature and the pressure of the naphtha are kept unchanged, and the treated naphtha is continuously discharged from the bottom of the reactor until the discharge of the naphtha is transparent.

In the step (2), hydrocarbons remaining on the surface of the ruthenium-based catalyst after naphtha treatment are removed using an inactive gas purge. In the present invention, the inactive gas refers to a gas that does not chemically react with the fischer-tropsch synthesis ruthenium-based catalyst and naphtha, and may be nitrogen, argon, helium or a combination thereof, and is preferably nitrogen. The temperature of the inactive gas during purging is 200-400 ℃, and the preferred temperature is 250-350 ℃; the pressure is 0.1MPa to 3MPa, preferably 2MPa to 3 MPa; the gas space velocity (GHSV) is 2000-6000 h^-1Preferably 3000-5000 h^-1(ii) a The time is 0.5 to 2 hours, preferably 1 hour. In this step, the purging may be terminated when the volume content of total hydrocarbons in the purge gas is less than 0.05ppm, which may be detected, for example, using a tail gas detection device.

In step (3), the oxygen-containing gas reacts with the carbon deposit and other organic matters in the catalyst to remove the carbon deposit. The metal of the catalyst and organic substances such as carbon on the surface are converted into metal oxides and carbon oxides by oxidation, so that any oxygen-containing gas can be used without damaging the ruthenium-based catalyst. For step (3), when CO is in the purge gas₂Less than 0.05ppm, the oxidation reaction can be terminated. The oxygen-containing gas used is oxygen, air, a heliox (e.g., a heliox in which the volume ratio of helium to oxygen is 10:90 to 30: 70), or a combination thereof, preferably air. In the step (3), the temperature of the treatment (oxidation) is 300-500 ℃, preferably 350-450 ℃; the pressure is 0.5MPa to 2MPa, preferably 1MPa to 1.5 MPa; GHSV of 2000-6000 h^-1Preferably 3000-5000 h^-1(ii) a The time is 0.5 to 2 hours, preferably 1 hour.

In the step (4), hydrogen is used in an amount of not less than 99% by volume, and hydrogen is also usedThe original conditions are as follows: normal pressure; the temperature is 250-450 ℃, and preferably 300-400 ℃; GHSV of 500-6000 h^-1Preferably 1000 to 2000 hours^-1(ii) a And (4) carrying out constant temperature treatment for 2-12 h, preferably 4-8 h.

The in-situ regeneration method provided by the invention can realize in-situ regeneration of the fixed bed ruthenium-based Fischer-Tropsch synthesis catalyst, the in-situ regeneration process is simple and convenient to operate and easy to realize, the used materials and reagents are low in price, and the interaction between metal and a carrier, and between active metal and an auxiliary agent is not changed. The method can eliminate the catalyst deactivation caused by carbon deposition, metal phase change and partial poison pollution, and remove long-chain products blocking the pore channel, thereby achieving the purpose of prolonging the service life of the Fischer-Tropsch synthesis ruthenium-based catalyst.