KR20220052010A - Fischer-Tropsch synthesis catalyst regeneration method - Google Patents

Abstract

The present invention relates to a regeneration method of a catalyst for Fischer-Tropsch synthesis and, more specifically, to a regeneration method of a catalyst for Fischer-Tropsch synthesis which improves process efficiency by regenerating a catalyst deactivated by the Fisher-Tropsch synthesis process in a reactor without a separate separation process.

Description

Fischer-Tropsch synthesis catalyst regeneration method

The present invention relates to a method for regenerating a catalyst for Fischer-Tropsch synthesis, and more particularly, to a Fischer-Tropsch synthesis that improves process efficiency by regenerating a catalyst deactivated by Fischer-Tropsch synthesis in a reactor without a separate separation process. It relates to a method for regenerating a catalyst for synthesis.

Fischer-Tropsch Synthesis (FTS) is a method for synthesizing liquid hydrocarbons from carbon monoxide and hydrogen, and from synthesis gas (H ₂ +CO) produced from coal, natural gas and biomass to liquid of hydrocarbons can be synthesized, which not only facilitates the supply and demand of raw materials, but also converts cheap raw materials such as coal and methane into hydrocarbons with high added value such as petroleum.

The Fischer-Tropsch synthesis catalyst is made by dispersing active metals such as iron, cobalt, nickel, and ruthenium in a support with a large specific surface area such as alumina, silica, titania, and magnesia having micropores, and the catalyst activity is high. It is possible to increase the production and overall carbon efficiency of hydrocarbons having 5 or more carbon atoms, and the cobalt-based catalyst has excellent carbon monoxide conversion rate, long catalyst life, and high hydrocarbon selectivity.

On the other hand, the Fischer-Tropsch synthesis catalyst decreases the catalytic active point due to catalyst poisons such as sulfur and nitrogen compounds contained in synthesis gas, inactivation due to oxidation of active metal, formation of a compound between active metal and support, and small active metal crystals. Due to the reduction of the active site due to sintering, the recrystallization of the atomic structure of the active metal surface, and the decrease in the active site of the catalyst due to carbon deposition, it is deactivated by long-term operation in the FTS reaction.

In general, the catalyst deactivated by the FTS reaction can be regenerated by the reduction-oxidation-reduction (ROR) process. Hydrogen flows so that hydrocarbons or oxides surrounding the deactivated metal catalyst are removed, and after that, the metal catalyst is converted to an oxide form by a gas containing oxygen in the catalyst converted to a metal state, and at the same time, the redispersion of the catalyst this happens The oxidized catalyst can be recycled through the process of reduction using hydrogen for use in the reaction.

Japanese Patent Registration No. 4903356 (2012.01.13.), which is a prior document, discloses separation of the catalyst from the slurry in order to reactivate the catalyst present on the slurry, followed by dewaxing and drying, followed by oxidation treatment. Korean Patent Publication No. 2009-214013 (2009.09.24.) discloses a method of extracting a mixed fluid composed of a catalyst used in a Fischer-Tropsch synthesis process from a reactor and regenerating it by high-temperature treatment under a reducing gas. However, the catalyst regeneration method of the prior literature is not a fixed bed reactor, but when it is applied to a fixed bed reactor, the process of extracting the catalyst in the reactor to the outside to regenerate the catalyst and then recharging the reactivated catalyst into the reactor is required. , the overall process efficiency is reduced. In order to overcome this disadvantage, when reactivation is performed inside the reactor, since the reaction conditions for oxide formation and hydrogen are higher than the Fischer-Tropsch synthesis reaction conditions, sintering of the cobalt metal catalyst may be caused.

In addition, in order to improve the process by simplifying the regeneration method, Korean Patent Registration No. 10-1792630 (2017.10.26.) discloses that in order to regenerate the catalyst in the reactor, high boiling point liquid hydrocarbons generated during the FTS reaction are used in the FTS synthesis reactor. It is disclosed to suppress and regenerate the deactivation of the catalyst due to wax deposition on the catalyst surface or reoxidation of metal cobalt by water generated during the reaction, etc. However, in the case of the prior literature, it is necessary to selectively re-supply to the reactor only unsaturated or saturated hydrocarbons having 6 to 12 carbon atoms among the liquid hydrocarbons produced by the FTS reaction, and an additional device or process for this may be required, so the overall process There is a limit to simplification.

Therefore, there is a need for a catalyst regeneration method for Fischer-Tropsch synthesis that can efficiently regenerate the catalyst without causing problems such as sintering of the metal catalyst while improving the process efficiency by regenerating the catalyst in the reactor.

Japanese Patent Registration No. 4903356 (2012.01.13.) Japanese Patent Application Laid-Open No. 2009-214013 (2009.09.24.) Korean Patent No. 10-1792630 (2017.10.26.)

The present invention is a Fischer-Tropsch synthesis process that improves the process efficiency by allowing the catalyst to be regenerated in the reactor without the need to separate and externally extract the catalyst in regenerating the catalyst whose activity has been reduced by the Fischer-Tropsch synthesis process. An object of the present invention is to provide a method for regenerating a catalyst for synthesis.

In order to solve the above problem, the catalyst whose activity has been lowered by the Fischer-Tropsch synthesis process is not separated from the reactor, but air is injected into the reactor in which the deactivated catalyst is filled, so that the pressure in the reactor is stagnated at atmospheric pressure to 10 bar It provides a method for regenerating a catalyst for Fischer-Tropsch synthesis, characterized in that the

In one embodiment, the method is regenerated by calcining a Fischer-Tropsch synthesis catalyst in an oxidizing atmosphere at a temperature of 200 to 600 ° C. can

In an embodiment, the firing may be performed for 30 to 600 minutes.

In one embodiment, the catalyst may be formed by dispersing cobalt as an active metal on a support made of any one or more selected from zeolite, alumina, silica, titania and magnesia.

In one embodiment, the cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O), cobalt chloride (CoCl ₂ ·6H ₂ O), cobalt bromide (CoBr ₂ ·6H ₂ O), cobalt iodide (CoI ₂ ·6H ₂ O), cobalt sulfate (CoSO ₄ ) and cobalt acetate (Co(CH ₃ COO) ₂ ·4H ₂ O) may be formed from any one or more cobalt precursors selected from the group consisting of.

In one embodiment, the catalyst may include 5 to 25 parts by weight of Co based on 100 parts by weight of the support.

In one embodiment, the oxidizing atmosphere is made of a gas in which O ₂ and an inert gas are mixed, and O ₂ may be included in an amount of 1 to 20 mol%.

In the present invention, as the catalyst deactivated by the Fischer-Tropsch reaction is regenerated in the reactor without a separate separation process, a series of processes of separating and regenerating the conventionally deactivated catalyst from the reactor and charging it back into the reactor can be omitted. , the process efficiency can be improved.

In addition, by regenerating the Fischer-Tropsch catalyst according to the present invention, it is possible to reduce the catalyst cost by increasing the catalyst life, and to reduce the amount of the spent catalyst, thereby reducing the treatment cost and environmental problems caused by the disposal of the catalyst can do it

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is those well known and commonly used in the art.

When a part "includes" a component throughout this specification, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

The in-situ regeneration described herein means that the Fischer-Tropsch catalyst is regenerated while it is present in the reactor, and the ex-situ regeneration means that the deactivated Fischer-Tropsch catalyst is separated from the reactor and regenerated.

Hereinafter, the present invention will be described in detail.

In one aspect of the present invention, without separating the catalyst whose activity has been lowered by the Fischer-Tropsch synthesis process from the reactor, air is injected into the reactor in a state in which the deactivated catalyst is charged, so that the pressure in the reactor is from atmospheric pressure to 10 bar It provides a regeneration method of a catalyst for Fischer-Tropsch synthesis, characterized in that it is stagnated as

During regeneration (in-situ regeneration) of the inactivated catalyst in the reactor, oxidation of the catalyst is performed by flowing a gas containing oxygen into the reactor at a constant flow rate, or stagnating at a constant pressure after injecting a gas containing oxygen into the reactor. This can be done by the method

When a gas containing air or oxygen is flowed into the reactor at a constant flow rate, the degree of catalyst regeneration is relatively low. It is regenerated to the extent that it has similar activity to the new catalyst. This is the effect of removing carbon or hydrocarbons adsorbed to the catalyst and redispersing catalyst particles when the oxidation gas is flowing in a certain flow rate, causing excessive oxidation and sintering of the catalyst active sites, and in the state where the oxidation gas is stagnant. there is However, when the pressure of the stagnant oxidizing gas is less than 1 bar, oxidation is not performed properly and the catalyst is not reactivated.

In the present invention, the activity of the reduced, Fischer-Tropsch catalyst for synthesis may be regenerated by calcining for 30 to 600 minutes in an oxidizing atmosphere at a temperature of 200 to 600° C. under the stagnant condition at 4 to 10 bar.

Specifically, when the calcination temperature in the oxidizing atmosphere is less than 200°C, materials such as carbon and hydrocarbons deposited on the catalyst surface are not removed, and when it exceeds 600°C, sintering occurs and catalyst reactivation is achieved. do not support Accordingly, the catalyst for Fischer-Tropsch synthesis with reduced activity is calcined at 200 to 600° C. in an oxidizing atmosphere under the above pressure to remove carbon and high boiling point hydrocarbons deposited on the catalyst surface, and cobalt as a support It is redispersed in , and the catalytic activity is regenerated. Preferably, the firing temperature may be 250 to 550 °C.

The sintering is carried out for 30 to 600 minutes under the stagnant conditions at 4 to 10 bar, preferably 200 to 400 minutes. When carried out for less than 30 minutes, oxidation is not sufficiently performed, and when it exceeds 150 minutes, the catalyst reactivation efficiency does not improve with respect to time, so that the process efficiency may be lowered.

In addition, in this case, the oxidizing atmosphere is made of a gas in which O ₂ and an inert gas are mixed, and contains 1 to 20 mol% of oxygen, and the type of inert gas is not limited, but may be He, N ₂ or Ar. When the O ₂ content is included in less than 1 mol%, oxidative calcination is not made, and when it exceeds 20 mol%, as oxygen is supplied in excess, there is a problem in that economic efficiency is lowered in the oxygen concentration process.

In the Fischer-Tropsch catalyst regeneration method according to the present invention, a hydrogenation reaction may be selectively performed before or after catalyst regeneration in the oxidizing atmosphere.

The catalyst of the present invention has cobalt dispersed as an active metal on a support made of at least one selected from zeolite, alumina, silica, titania and magnesia, and is used in the Fischer-Tropsch synthesis process to obtain an intermediate fraction (liquid) from synthesis gas. fuel) can be selectively manufactured.

In the catalyst, the support is used for the purpose of widely dispersing the active metal component of the catalyst, and has an effect on the physical and chemical properties of the catalyst due to strong metal-support interaction (SMSI) with the active metal. As possible, it may preferably be zeolite or a mixture of zeolite and alumina.

The zeolite is a microporous solid family of aluminosilicate (SiO ₄ ^4- and AlO ₄ ^5- ) members known as molecular sieves, and is generally composed of Si, Al, O and metals, and has physical and chemical properties. There are about 50 types of zeolites (clinoptilolite, chabazite, phillipsite, mordenite, etc. ⁾ according to the It has a characteristic that it is not easily decomposed even at a high temperature of from 900°C. Depending on the crystal structure, Zeolite-A, Zeolite-β ZSM-5, ZSM-22, Zeolite-X, Zeolite-Y, Zeolite-L, etc. exist. In the present invention, any one or more of these is used as the zeolite support, but is not particularly limited.

In the catalyst, the active metal includes cobalt. Cobalt has the advantages of high activity, long lifespan, and low CO ₂ production and high production yield of liquid paraffinic hydrocarbons. It is mainly used as a catalyst. Cobalt nitrate (Co(NO ₃ ) ₂ .6H ₂ O), cobalt chloride (CoCl ₂ .6H ₂ O), cobalt bromide (CoBr ₂ .6H ₂ O), cobalt iodide (CoI ₂ .6H) ₂ O), cobalt sulfate (CoSO ₄ ) and cobalt acetate (Co(CH ₃ COO) ₂ .4H ₂ O) may be formed from any one or more cobalt precursors selected from the group consisting of, in the present invention, Co is Based on 100 parts by weight of the support, 5 to 25 parts by weight are included. This is, when Co is included in less than 5 parts by weight, the catalyst is not sufficiently activated during the Fischer-Tropsch synthesis reaction, and when it exceeds 25 parts by weight, deactivation may occur due to sintering by excess Co. Because.

The catalyst may further include a promoter to enhance catalytic activity such as improvement in reactivity, selectivity and thermal stability. As the co-catalyst, various metal oxides such as Ru, Rh, and Pt-based noble metals and K, Zn, La, and Mg may be used.

Hereinafter, examples will be given for a more detailed description of the present invention. However, the following examples are only preferred examples of the present invention, and the present invention is not limited thereto.

<Example>

1. FTS catalyst preparation

Using ZSM-5 (Zeolyst) having a Si/Al ratio of 15 as a support, water and cobalt nitrate hexahydrate were mixed and kneaded for about 10 minutes. The obtained dough-like paste was extruded to a diameter of 1.5 to 2.0 mm using an extruder, dried first at room temperature for one day, and then secondarily dried in an oven at 110° C. for 5 hours. Thereafter, the FTS catalyst was prepared by calcination at 550° C. in an air atmosphere for 5 hours.

20% by weight of Co is included in the total weight of the prepared FTS catalyst, the remaining 80% is a support, and the support consists of 70% by weight of ZSM-5 and 30% by weight of boehmite.

2. FTS reaction

After filling the reactor with the FTS catalyst, reducing it with 5% H ₂ /Ar gas at atmospheric pressure and 400 ° C. for 5 hours to activate it, and then injecting syngas into the reactor through MFC (Mass Flow Controller), 20 bar And the FTS reaction was performed at 250 °C. At this time, the flow rate of the syngas, GHSV (ml/g cat/h) was 4000h ^-1 , and the H ₂ /CO molar ratio in the syngas was 2.0 (based on CH ₄ ).

3. Catalyst regeneration

Example 1

After the FTS process, air is injected into the reactor without separating the deactivated catalyst from the reactor, so that the pressure in the reactor is stagnated at 4 bar, and under the oxidation atmosphere stagnated at 4 bar, at a temperature of 350° C. After calcination for 300 minutes, the catalyst was regenerated.

Example 2

After the FTS process, 5% H ₂ /Ar is injected into the reactor in a state where the deactivated catalyst is not separated from the reactor, hydrogenated at 400° C., purged sufficiently, and air is injected into the reactor, the pressure in the reactor was allowed to stagnate at 4 bar, and was calcined for 300 minutes at a temperature of 350° C. under an oxidizing atmosphere stagnated at 4 bar, to regenerate the catalyst.

Comparative Example 1

After the FTS process, the inactivated catalyst was separated from the reactor and calcined for 300 minutes at a temperature of 350° C. and stagnant air in a crucible prepared outside to regenerate the catalyst.

Comparative Examples 2 to 4

After the FTS process, without separating the deactivated catalyst from the reactor, air was supplied into the reactor at 10, 20 and 30 cc/min, respectively, and calcined at 350° C. for 300 minutes to regenerate the catalyst.

Comparative Example 5

After the FTS process, 5% H ₂ /Ar was injected into the reactor in a state in which the deactivated catalyst was not separated from the reactor, and after hydrogenation at 400° C., 5 mol% O ₂ was introduced into the reactor 200 cc It was supplied at /min and calcined for 300 minutes at a temperature of 350°C to regenerate the catalyst.

FTS reaction with regenerated catalyst

The FTS process was re-executed with each of the regenerated catalysts and fresh catalysts, and the results are shown in Table 1 below.

catalyst Primary hydrogenation Catalyst regeneration (oxidation) conditions CO conversion rate
(%) Catalyst separation
Whether air condition temperature
(℃) fresh catalyst - - - - 74.25 Example 1 - unseparated 4 bar air 350 71.75 Example 2 ○ unseparated 1 bar air 350 74.02 Comparative Example 1 - separation stagnant air 350 73.59 Comparative Example 2 - unseparated air flow 10cc/min 350 50.02 Comparative Example 3 - unseparated air flow 20cc/min 350 55.46 Comparative Example 4 - unseparated air flow 30cc/min 350 60.03 Comparative Example 5 ○ unseparated 5mol% O ₂ flow (200cc/min) 350 40.89

From Table 1, in a state in which the deactivated catalyst was not separated (in-situ), Examples 1 and 2 were regenerated by pressing with 1 or 4 bar air, and the deactivated catalyst was separated (ex-situ) and stagnant Comparative Example 1, which was regenerated under old air (stagnant air) conditions, showed a CO conversion rate similar to the result of using the fresh catalyst, so it can be seen that the catalyst was reactivated through the catalyst regeneration process.

However, unlike Example 1, in Comparative Example 1, it is necessary to separate the deactivated catalyst from the reactor and regenerate it and then charge it back into the reactor, thereby reducing process efficiency.

On the other hand, as in Example 1, the inactivated catalyst was regenerated in an in-situ state, but Comparative Examples 2 to 4 and 5 mol% in which the catalyst was regenerated under an air flow condition of 10, 20 or 30 cc/min In Comparative Example 5, in which the catalyst was regenerated under O ₂ flow conditions, the CO conversion rate was as low as about 40 to 60%, so it can be seen that the catalyst regeneration was not performed properly.

Claims (7)

The Fischer-Tropsch synthesis process does not separate the catalyst whose activity is lowered from the reactor, but injects air into the reactor in which the deactivated catalyst is filled, characterized in that the pressure in the reactor is stagnated at atmospheric pressure to 10 bar, Fischer - Regeneration method of catalyst for Tropsy synthesis.
The method of claim 1,
The method is characterized in that under the condition that the pressure in the reactor is stagnated at 1 to 10 bar, the activity in the reactor is lowered, the Fischer-Tropsch catalyst for synthesis is calcined in an oxidizing atmosphere at a temperature of 200 to 600 ° C. , Regeneration method of catalyst for Fischer-Tropsch synthesis.
3. The method of claim 2,
The sintering is characterized in that 30 to 600 minutes, Fischer-Tropsch regeneration method of the catalyst for synthesis.
The method of claim 1,
The catalyst is a catalyst for Fischer-Tropsch synthesis, characterized in that cobalt is dispersed as an active metal on a support made of at least one selected from zeolite, alumina, silica, titania and magnesia.
5. The method of claim 4,
The cobalt is cobalt nitrate (Co(NO ₃ ) ₂ ·6H ₂ O), cobalt chloride (CoCl ₂ ·6H ₂ O), cobalt bromide (CoBr ₂ ·6H ₂ O), cobalt iodide (CoI ₂ ·6H) ₂ O), cobalt sulfate (CoSO ₄ ) and cobalt acetate (Co(CH ₃ COO) ₂ .4H ₂ O) characterized in that it is formed from any one or more cobalt precursors selected from the group consisting of, Fischer-Tropsch synthesis A method for regenerating a catalyst.
5. The method of claim 4,
The catalyst is based on 100 parts by weight of the support, Co, characterized in that it comprises 5 to 25 parts by weight, Fischer-Tropsch regeneration method of the catalyst for synthesis.
3. The method of claim 2,
The oxidizing atmosphere is made of a gas in which O ₂ and an inert gas are mixed, and O ₂ is characterized in that it contains 1 to 20 mol%, Fischer-Tropsch regeneration method of a catalyst for synthesis.