KR102750305B1 - Continuous syngas-production method and syngas-production system comprising regeneration of reforming catalysts deactivated by coking - Google Patents

Abstract

The present invention relates to a continuous operation method for producing synthesis gas, which can improve the production efficiency of synthesis gas while preserving the activity of a reforming catalyst. Specifically, the continuous operation method for producing synthesis gas includes: a first mode for supplying a hydrocarbon gas stream containing methane and a first stream containing carbon dioxide to the inlet of a multi-tubular reforming reactor in which each reforming catalyst is positioned, thereby producing a synthesis gas containing hydrogen and carbon monoxide which is discharged through the outlet of the multi-tubular reforming reactor; and a second mode for blocking the hydrocarbon gas stream and selectively or sequentially supplying the first stream to at least one of the multi-tubular reforming reactors to regenerate the reforming catalyst in which coke is deposited; and is characterized in that the hydrocarbon gas stream and the first stream are continuously supplied to another reforming reactor while the second mode is being performed, so that the first mode is continuously operated.

Description

Continuous syngas-production method and syngas-production system comprising regeneration of reforming catalysts deactivated by coking during syngas production

The present invention relates to a continuous operation method for producing synthesis gas including regeneration of a reforming catalyst and a synthesis gas production system, and more particularly, to a continuous operation method including regeneration of a reforming catalyst deactivated by coking and a synthesis gas production system, which continuously maintains production of synthesis gas by mainly reacting hydrocarbons and carbon dioxide.

In the reaction process of producing synthesis gas through the reforming reaction of carbon dioxide and hydrogen contained in biogas or steel mill by-product gas, high temperature and low steam-to-carbon ratio operating conditions are sometimes required to increase the conversion rate of carbon dioxide.

A reforming catalyst is built into the reactor used in this reforming reaction process, but there is a problem in which carbon components are deposited on the surface of the reforming catalyst under the operating conditions described above.

These deposits are called coke, and the phenomenon in which coke is generated is called coking. If the amount of coke generated on the reforming catalyst increases due to the coking phenomenon, permanent catalytic performance loss and increased pressure drop in the catalyst layer inevitably lead to difficulties in stable operation of the process.

To solve these problems, Korean Patent Publication No. 10-2012-0074400 provides a method for regenerating a reforming catalyst by supplying steam. However, transition metal catalysts have the disadvantage that the active sites are easily oxidized by the steam supplied for regeneration, which damages the catalyst, and that a separate reduction process is additionally required, and that normal operation for producing synthesis gas is impossible when coke is removed.

Accordingly, a technology is needed to efficiently remove coke formed on a reforming catalyst and regenerate the reforming catalyst on which coke has been deposited, as well as a technology to continuously operate the synthesis gas production process without interruption even during the coke removal process to improve production efficiency.

Republic of Korea Publication Patent No. 10-2012-0074400

The purpose of the present invention is to provide a continuous operation method for producing synthesis gas capable of regenerating the activity of a reforming catalyst whose activity has been reduced by coking and at the same time continuously maintaining the production of synthesis gas.

Another object of the present invention is to provide a synthesis gas production system capable of improving the production efficiency of synthesis gas.

A continuous operation method for producing synthesis gas according to one aspect of the present invention comprises: a first mode for supplying a hydrocarbon gas stream containing methane and a first stream containing carbon dioxide to the inlet of a multi-tubular reforming reactor in which each reforming catalyst is positioned, thereby producing a synthesis gas containing hydrogen and carbon monoxide which is discharged through the outlet of the multi-tubular reforming reactor; and a second mode for blocking the hydrocarbon gas stream and selectively or sequentially supplying the first stream to at least one of the multi-tubular reforming reactors to regenerate the reforming catalyst in which coke is deposited; wherein, while the second mode is performed, the hydrocarbon gas stream and the first stream are continuously supplied to another reforming reactor, so that the first mode is continuously operated.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the second mode can be started when the following condition 1 is satisfied.

(Condition 1)

ΔP _t > 1.1 x ΔP _i

ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the initial stage when the first mode is performed.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the second mode may be terminated when at least one selected from the following conditions 1 to 3 is satisfied.

Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900℃.

Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)

Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the first mode can be performed by additionally supplying a steam stream.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, a dry reforming reaction may occur in the reforming reactor in which hydrocarbon gas is reformed by reacting it with carbon dioxide, or a combined reforming reaction may occur in which hydrocarbon gas is reformed by reacting it with carbon dioxide and water vapor simultaneously.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the molar ratio of hydrocarbon gas:carbon dioxide supplied to the reforming reactor for the dry reforming reaction may be 1:1 to 2.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the molar ratio of hydrocarbon gas:steam supplied to the reforming reactor for the complex reforming reaction may be 1:0.1 to 1.5.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the reforming catalyst may include at least one transition metal selected from iron (Fe), aluminum (Al), nickel (Ni), chromium (Cr), palladium (Pd), rhodium (Rh), and platinum (Pt).

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, coke deposited in the second mode can be removed by a reverse Boudouard reaction.

In a continuous operation method for producing synthesis gas according to one embodiment of the present invention, the regeneration of the reforming catalyst can be performed at a temperature of 500 to 900°C.

In another aspect, the present invention provides a synthesis gas production system.

According to another aspect of the present invention, a synthesis gas production system comprises: a raw material supply unit into which a first stream including a hydrocarbon gas stream and carbon dioxide, which are independent raw materials, are independently supplied through a supply pipe; and a reforming reactor having a multi-tubular reforming reactor, each of which is equipped with a reforming catalyst; wherein the raw materials are supplied to the inlets of the reforming reactors through the supply pipes communicated with each of the reforming reactors to produce a synthesis gas including hydrogen and carbon monoxide discharged from the outlet of the reforming reactor, wherein the first stream is supplied to at least one reforming reactor, and the supply of raw materials except for the first stream to the one reforming reactor is blocked to regenerate a reforming catalyst in which coke is deposited, and the raw materials are continuously supplied to another reforming reactor.

In a synthesis gas production system according to one embodiment of the present invention, the start of the regeneration of the reforming catalyst in which the coke is deposited is controlled by the following conditional expression 1, and the end of the regeneration of the reforming catalyst can be controlled by one or more factors selected from the following conditions 1 to 3.

(Condition 1)

ΔP _t > 1.1 x ΔP _i

ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the initial stage when the first mode is performed.

Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900℃.

Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)

Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less.

In a synthesis gas production system according to one embodiment of the present invention, the raw material supply unit may further supply steam as a raw material.

In a synthesis gas production system according to one embodiment of the present invention, a carbon dioxide separation unit positioned at the rear end of the reforming reaction unit for separating and capturing unreacted carbon dioxide may be further included.

In a synthesis gas production system according to one embodiment of the present invention, the separated and captured carbon dioxide can be resupplied to at least one reforming reactor of the reforming reaction unit to produce synthesis gas or regenerate a reforming catalyst on which coke has been deposited.

According to one embodiment of the present invention, a continuous operation method for producing synthesis gas comprises: a first mode for supplying a hydrocarbon gas stream containing methane as a main component and a first stream containing carbon dioxide to the inlet of a multi-tubular reforming reactor in which each reforming catalyst is positioned, thereby producing a synthesis gas containing hydrogen and carbon monoxide discharged from the outlet of the multi-tubular reforming reactor; and a second mode for blocking the hydrocarbon gas stream and selectively or sequentially supplying the first stream to at least one of the multi-tubular reforming reactors to regenerate the reforming catalyst in which coke is deposited; wherein, while the second mode is performed, the hydrocarbon gas stream and the first stream are continuously supplied to another reforming reactor, thereby continuously operating the first mode, thereby having an advantage in that the activity of the reforming catalyst can be preserved while continuously maintaining the production of the synthesis gas.

FIG. 1(a) and FIG. 1(b) are diagrams illustrating a process diagram of a synthesis gas production system including an initial synthesis gas production system and a regeneration process of a reforming catalyst with coke deposited thereon, respectively, according to one embodiment of the present invention.
FIG. 2 is a drawing illustrating a process diagram of a synthesis gas production system according to another embodiment of the present invention.
FIG. 3 is a drawing illustrating a process diagram of a synthesis gas production system according to another embodiment of the present invention.
FIG. 4 is a drawing illustrating the result of catalyst regeneration performed according to one embodiment of the present invention.
FIG. 5 is a diagram illustrating a change in CO concentration according to the regeneration time of a catalyst performed according to one embodiment of the present invention.

Hereinafter, with reference to the attached drawings, a continuous operation method for producing synthesis gas and a synthesis gas production system according to an embodiment of the present invention will be described in detail. The drawings introduced below are provided as examples so that those skilled in the art can sufficiently convey the spirit of the present invention. Therefore, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be illustrated in an exaggerated manner to clarify the spirit of the present invention. At this time, if there is no other definition in the technical and scientific terms used, they have the meaning commonly understood by those skilled in the art to which this invention belongs, and a description of well-known functions and configurations that may unnecessarily obscure the gist of the present invention in the following description and the attached drawings will be omitted.

Additionally, the singular forms used in the specification and the appended claims are intended to include the plural forms as well, unless the context clearly dictates otherwise.

The terms “include” or “have” in this specification and the appended claims mean that a feature or component described in the specification is present, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

A continuous operation method for producing synthesis gas according to one aspect of the present invention comprises: a first mode for supplying a hydrocarbon gas stream containing methane as a main component and a first stream containing carbon dioxide to the inlet of a multi-tubular reforming reactor in which each reforming catalyst is positioned, thereby producing a synthesis gas containing hydrogen and carbon monoxide discharged from the outlet of the multi-tubular reforming reactor; and a second mode for blocking the hydrocarbon gas stream and selectively or sequentially supplying the first stream to at least one of the multi-tubular reforming reactors to regenerate the reforming catalyst in which coke is deposited; wherein, while the second mode is performed, the hydrocarbon gas stream and the first stream are continuously supplied to another reforming reactor, so that the first mode is continuously operated.

Conventionally, in order to remove coke deposited on a reforming catalyst, gas such as steam or air (oxygen) is supplied into a reforming reactor to oxidize the coke. However, reforming catalysts of the transition metal series have the disadvantage that active sites are easily oxidized by the supplied steam, thereby damaging the reforming catalyst, or that a separate reduction process is additionally required to reduce the oxidized reforming catalyst.

On the other hand, a continuous operation method for producing synthesis gas according to one embodiment of the present invention supplies a hydrocarbon gas stream and a first stream containing carbon dioxide to a multi-tubular reforming reactor in which each reforming catalyst is positioned to produce a synthesis gas containing hydrogen and carbon monoxide (first mode), but when a phenomenon in which the activity of the catalyst layer is reduced or the operation stability is impaired due to coking is detected, the hydrocarbon gas stream is blocked and the first stream containing carbon dioxide is selectively or sequentially supplied to at least one multi-tubular reforming reactor to regenerate the reforming catalyst in which coke is deposited (second mode), and at the same time, in another reforming reactor in which the second mode is not performed, the first mode is continuously operated, so that the activity of the reforming catalyst can be preserved and the production of the synthesis gas can be continuously maintained.

In addition, since carbon dioxide, one of the raw materials, is used in the production of synthesis gas and in the regeneration of the reforming catalyst, there is an advantage in that the reforming catalyst is free from damage due to oxidation and a separate reduction process is unnecessary. In addition, since the utilization of carbon dioxide, a greenhouse gas, can be increased, the emission of carbon dioxide can be suppressed, and thus global warming caused by the greenhouse effect can be prevented.

As an example, a first mode in which a synthesis gas containing hydrogen and carbon monoxide is produced can be performed by supplying a hydrocarbon gas stream containing methane and a first stream containing carbon dioxide to a multi-tubular reforming reactor in which each reforming catalyst is positioned.

At this time, the hydrocarbon gas may include methane gas and may also include carbon dioxide at the same time. As a non-limiting example, the methane gas may be derived from one or more feedstocks selected from, but not limited to, natural gas, naphtha, gasoline, kerosene, coal, biomass, and steel mill by-product gas.

In one specific example, a first stream containing a hydrocarbon gas stream and carbon dioxide is supplied to a multi-tubular reforming reactor, each of which has a reforming catalyst positioned therein, so that a synthesis gas containing hydrogen and carbon monoxide can be produced in each reforming reactor through a dry reforming reaction of the following reaction scheme 1.

(Reaction Formula 1)

CH ₄ + CO ₂ →2CO + 2H ₂

While the dry reforming reaction, which is an endothermic reaction as shown in Reaction Scheme 1, occurs as the main reaction, side reactions as shown in Reaction Schemes 2 and 3 below may occur simultaneously.

(Reaction formula 2)

CH ₄ →C (s) + 2H ₂

A side reaction, such as that shown in Reaction Scheme 2, which can occur simultaneously during a dry reforming reaction occurs through direct thermal decomposition of hydrocarbons, and the carbon (coke) produced is deposited on the reforming catalyst, thereby reducing the activity of the reforming catalyst.

(Reaction Formula 3)

2CO →C (s) + CO ₂

In addition, after CO generated through the dry reforming reaction is adsorbed on the surface of the reforming catalyst, carbon deposition occurs on the reforming catalyst through the Boudouard reaction of Reaction Scheme 3, thereby reducing the activity of the catalyst.

In one embodiment, the first mode can be performed by supplying additional steam streams.

By supplying a steam stream in addition to the hydrocarbon gas stream and the first stream to perform the first mode, the reaction of the following reaction formula 4 can additionally occur in the reforming reactor.

(Reaction Formula 4)

CH ₄ + H ₂ O → CO + 3H ₂

As shown in Scheme 4, the production amount of hydrogen contained in the synthesis gas can be further increased through a combined reforming reaction that reforms hydrocarbons by using hydrocarbon gas, carbon dioxide, and steam as reactants, i.e., by the additionally supplied steam stream in the first mode.

At this time, the molar ratio of hydrocarbon gas:carbon dioxide supplied to the reforming reactor for the dry reforming reaction may be 1:1 to 3, specifically 1:1 to 2.

Additionally, the molar ratio of hydrocarbon gas: steam supplied to the reforming reactor for the complex reforming reaction may be 1:0.1 to 2, specifically 1:0.1 to 1.5.

The conditions described above are conditions in which coking easily occurs on the surface of the reforming catalyst in the temperature range (600 - 900°C) where normal reforming reactions occur.

Specifically, if more steam is supplied as a raw material for the production of synthesis gas, the hydrogen production can be increased, but the conversion rate of carbon dioxide by reaction scheme 1 (dry reforming reaction) relatively decreases according to the thermodynamic equilibrium relationship. Conversely, if the amount of steam is reduced, the conversion rate of carbon dioxide increases, but the possibility of coke formation due to side reactions may increase.

In this way, coke deposited on the reforming catalyst can reduce the activity of the catalyst, and if the amount of coke deposited on the reforming catalyst continues to increase, the activity of the reforming catalyst can be permanently lost, and problems can arise in the stable operation of the synthesis gas production process due to the increased pressure build-up in the catalyst layer.

Accordingly, in order to operate the synthesis gas production process stably and at the same time improve the production efficiency of the synthesis gas, continuous management of the reforming catalyst with coke deposited on it is necessary.

In one embodiment, the reforming catalyst may include one or more transition metals selected from iron (Fe), aluminum (Al), nickel (Ni), chromium (Cr), palladium (Pd), rhodium (Rh), and platinum (Pt).

At this time, the above-mentioned reforming catalyst may be in a form supported on a carrier widely known in the art, and as a non-limiting example, the carrier may be at least one selected from alumina, zirconia, silica, zeolite, and mixtures thereof, but is not limited thereto.

In one embodiment, a second mode may be performed in which the hydrocarbon gas stream is blocked and a first stream containing carbon dioxide is selectively or sequentially supplied to at least one of the multi-tubular reforming reactors to regenerate the reforming catalyst in which coke is deposited.

As a specific example, the coke deposited in the second mode may be removed by a reverse Boudouard reaction.

Since the reverse Buddha reaction is an endothermic reaction, similar to the reactions of the above-mentioned reaction schemes 1 and/or 4, it can have the advantage of not having to worry about heat management when changing the operation mode (from the first mode to the second mode) to regenerate the reforming catalyst on which coke has been deposited.

In addition, since carbon dioxide, a reactant of the synthesis gas production process, is used, there is no risk of fire and/or explosion, the product generated during the coke removal process is carbon monoxide contained in the synthesis gas, so a separate separation process is not required, and the reforming catalyst, which is a transition metal, is free from the problem of damage due to oxidation.

Specifically, the second mode for regenerating a reforming catalyst in which coke is deposited in at least one reforming reactor is selectively or sequentially performed, while the first mode for continuously supplying a hydrocarbon gas stream and a first stream containing carbon dioxide to another reforming reactor in which the second mode is not performed to produce synthesis gas can be continuously operated.

While the regeneration of the reforming catalyst is in progress in one reforming reactor including a reforming catalyst with coke deposited thereon, a first stream containing a hydrocarbon gas stream and carbon dioxide as raw materials is continuously supplied to another reforming reactor so that synthesis gas can be continuously produced. Therefore, there is an advantage in that the activity of the reforming catalyst can be preserved while the production of synthesis gas can be continuously maintained, thereby improving production efficiency.

At this time, if the first mode in which synthesis gas is produced is performed by supplying an additional steam stream, the steam stream may be blocked along with the hydrocarbon gas stream when the second mode in which the reforming catalyst is regenerated is performed.

The reforming catalyst with coke deposited thereon can also be regenerated by steam. However, if steam is used to regenerate the reforming catalyst, the reforming catalyst may be oxidized and damaged, or a separate reduction process must be performed to reduce the oxidized reforming catalyst. Therefore, the second mode for regenerating the reforming catalyst with coke deposited thereon is advantageously performed by blocking the hydrocarbon gas stream and the steam stream and selectively or sequentially supplying the first stream containing carbon dioxide.

In one embodiment, the second mode for regeneration of the reforming catalyst can be started when the following condition 1 is satisfied.

(Condition 1)

ΔP _t > 1.1 x ΔP _i

ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the initial stage when the first mode is performed.

During the first mode through the reforming reaction of hydrocarbon gas, as described above, the catalytic activity of the reforming catalyst is reduced due to coke deposited by the coking phenomenon by side reactions such as reaction formula 2 and/or reaction formula 3, and the production yield of the synthesis gas is also reduced.

Accordingly, when the first mode is performed for an arbitrary time (t) and coke is deposited on the reforming catalyst, the pressure difference (ΔP _t ) at the inlet of the reforming reactor where the reactant is supplied and the outlet of the reforming reactor where the synthesis gas is discharged may be different from the pressure difference (ΔP _i ) before the initial reforming reaction, i.e., coke is deposited on the reforming catalyst.

At this time, the second mode for regeneration of the reforming catalyst on which coke has been deposited may be started when the pressure difference (ΔP _t ), defined as the difference between the pressures measured at the inlet and the outlet of the reforming reactor (P _inlet - P _outlet ) after the first mode has been performed for an arbitrary time (t), exceeds 1.1, 1.2, 1.3, 1.4, or 1.5 times the pressure difference (ΔP _i ) before coke is deposited on the reforming catalyst at the beginning of the reforming reaction, and may be started when it is substantially less than 2.0 times.

If the start of the second mode described above is performed when ΔP _t is 2.0 times or more based on ΔP _i , the regeneration efficiency of the reforming catalyst on which coke has been deposited may decrease, and as a result, the time required for the regeneration of the reforming catalyst may increase, which may lower the synthesis gas production efficiency. If it is performed when it is 1.1 times or less, the time required for the regeneration of the reforming catalyst may be shortened, but since the reforming catalyst is still active, the loss due to the mode change (from the second mode to the first mode) may be greater than the synthesis gas production efficiency, which may lower the synthesis gas production efficiency. Therefore, it is preferable that the second mode be started when the conditional expression 1 described above is satisfied.

As an example implementation, the second mode may be terminated if any one or more of the following conditions are satisfied.

Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900 ℃.

Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)

Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less.

Specifically, the second mode, in which coke deposited on the reforming catalyst is removed, may be terminated when the temperature of the reforming reactor reaches a temperature that may permanently damage the reforming catalyst provided in the reforming reactor during the second mode.

As a specific example, if the maximum temperature of the catalyst bed of the reforming reactor during the second mode exceeds 1300°C, 1200°C, 1100°C, 1000°C, or 900°C, the second mode may be terminated to prevent permanent damage to the reforming catalyst. In this case, it goes without saying that the above-mentioned temperature range may be adjusted according to the reforming catalyst provided in the reforming reactor.

For example, the regeneration of the reforming catalyst may be performed at a temperature of 500 to 1300°C, specifically 600 to 1100°C, more specifically 500 to 900°C, 700 to 900°C.

In addition, the second mode can be terminated when ΔP _t is less than 1.03 times, less than 1.02 times, or less than 1.01 times based on ΔP _i . That is, the second mode can be terminated when the pressure difference at the inlet and outlet of the reforming reactor caused by the carbon dioxide supplied for removing coke deposited on the reforming catalyst satisfies the above-mentioned range.

In addition, the second mode can be terminated when the concentration of carbon monoxide discharged from the outlet of the reforming reactor is 5 mol% or less, 4 mol% or less, or 3 mol% or less, and can be terminated when it is substantially 0.5 mol% or more, or more substantially 1.0 mol% or more.

Carbon dioxide and coke supplied through the second mode react (reverse Bodda reaction) to generate carbon monoxide. At this time, the concentration of carbon monoxide discharged through the outlet of the reforming reactor may decrease as the reforming catalyst is regenerated, and the second mode may be terminated when the aforementioned concentration standard is satisfied.

As a specific example, if the concentration of carbon monoxide discharged through the outlet of the reforming reactor exceeds 5 mol%, the reforming catalyst still contains deposited coke, so when switching back to the first mode, coke deposition may be accelerated, and if the second mode is performed until the concentration of carbon monoxide satisfies less than 0.5 mol%, the performance time of the second mode may increase, which may lower the efficiency for producing synthesis gas. Therefore, it is advantageous for the second mode to be terminated when the concentration of carbon monoxide discharged through the outlet of the reforming reactor satisfies the above-mentioned range.

As described above, since the start and end of the second mode are performed according to the conditions described above, permanent damage to the reforming catalyst due to coking during the reforming reaction is prevented, while the activity of the reforming catalyst is preserved, thereby improving the production efficiency of the synthesis gas.

As an example, the continuous operation method for producing synthesis gas may further include a third mode for separating and recovering unreacted carbon dioxide contained in the synthesis gas produced.

At this time, the unreacted carbon dioxide separated and recovered through the third mode can be used as a raw material for producing synthesis gas in the first mode or for regenerating the reforming catalyst in the second mode.

Specifically, the unreacted carbon dioxide separated and recovered by the third mode can be performed using a carbon dioxide separation and recovery process known in the art, and the separated carbon dioxide can be recycled to at least one reforming reactor and used as a material for regenerating a raw material or a reforming catalyst on which coke is deposited. Through this, not only can the resource efficiency be improved by reusing the unreacted carbon dioxide, but there is also an advantage in preventing the greenhouse effect by minimizing carbon dioxide emissions.

As a non-limiting example, separation and recovery of carbon dioxide can be performed using methods such as, but not limited to, absorption, adsorption, low temperature distillation, and membrane systems.

The present invention provides a synthesis gas production system according to another aspect.

According to one embodiment of the present invention, a synthesis gas production system comprises: a raw material supply unit into which a hydrocarbon gas stream including methane, which are independent raw materials, and a first stream including carbon dioxide are independently supplied through supply pipes; and a reforming reactor having a multi-tubular reforming reactor, each of which is equipped with a reforming catalyst; wherein the raw materials are supplied to the inlets of the reforming reactors through the supply pipes communicated with each of the reforming reactors to produce a synthesis gas including hydrogen and carbon monoxide discharged from the outlet of the reforming reactors, wherein the first stream is supplied to at least one reforming reactor, and the supply of raw materials except for the first stream to the one reforming reactor is blocked to regenerate a reforming catalyst in which coke is deposited, and the raw materials are continuously supplied to another reforming reactor.

At this time, the hydrocarbon gas stream may further contain carbon dioxide.

In detail, a synthesis gas production system according to one embodiment of the present invention supplies a hydrocarbon gas stream including methane and a first stream including carbon dioxide from a raw material supply unit through supply pipes independently connected to a plurality of reforming reactors to produce a synthesis gas including hydrogen and carbon monoxide, wherein the first stream is supplied to at least one reforming reactor, and the supply of the hydrocarbon gas stream to the one reforming reactor is blocked to regenerate a reforming catalyst having coke deposited thereon, and at the same time, raw materials for synthesis gas production are continuously supplied to another reforming reactor to preserve the activity of the reforming catalyst and continuously maintain production of the synthesis gas.

And at this time, the flow rate of the first stream containing carbon dioxide can be adjusted according to the synthesis gas production conditions, and optimal flow rate adjustment is also possible in the reforming catalyst regeneration mode.

Hereinafter, a synthesis gas production system according to one embodiment of the present invention will be described in more detail through drawings.

FIG. 1(a) and FIG. 1(b) are diagrams illustrating a process diagram of a synthesis gas production system including an initial synthesis gas production system and a regeneration process of a reforming catalyst with coke deposited thereon, respectively, according to one embodiment of the present invention.

As illustrated in Fig. 1(a), a hydrocarbon gas stream containing methane and a first stream containing carbon dioxide from a raw material supply unit (10) are each independently supplied to a multi-tubular reforming reactor (210 to 240) including a reforming catalyst provided in a reforming reaction unit (20), thereby producing a synthesis gas containing hydrogen and carbon monoxide.

Here, the reforming reaction unit (20) may include a plurality of reforming reactors, but the present invention is not limited to the number of reforming reactors provided.

As described above, during the reforming reaction process for producing synthesis gas, the reforming catalyst included in the reforming reactor may have its catalytic activity deteriorated compared to the initial state due to coke deposition caused by direct thermal decomposition of hydrocarbons and/or Boudouard reaction.

At this time, as shown in Fig. 1(b), the first stream is supplied to a reforming reactor (240) including a reforming catalyst with reduced catalytic activity, but the supply of hydrocarbon gas is blocked to regenerate the reforming catalyst on which coke has been deposited through a reverse Budar reaction.

At the same time, raw materials such as hydrocarbons and carbon dioxide can be continuously supplied to other reforming reactors (210 to 230) to continuously produce synthesis gas without complete system interruption.

As described above, the regeneration of the reforming catalyst in which coke has been deposited can be selectively or sequentially performed to preserve the activity of the reforming catalyst while continuously producing synthesis gas, thereby improving the production efficiency of synthesis gas.

In one embodiment, the start of the regeneration of the reforming catalyst in which coke is deposited is controlled by the following conditional expression 1, and the end of the regeneration of the reforming catalyst can be controlled by one or more factors selected from the following conditions 1 to 3.

(Condition 1)

ΔP _t > 1.1 x ΔP _i

ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the initial stage when the first mode is performed.

Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900℃.

Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)

Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less.

Specifically, the start and end of the regeneration of the reforming catalyst in which coke is deposited can be controlled through a control unit (not shown) based on conditional expression 1 and conditions 1 to 3, respectively, and the description based on conditional expression 1 and conditions 1 to 3 is similar to or identical to that described above, so a detailed description is omitted.

In one embodiment, as illustrated in FIG. 2, the raw material supply unit (10) may further include steam as a raw material and supply it to the multi-tubular reforming reactors (210 to 240) each including a reforming catalyst provided in the reforming reaction unit (20).

At this time, the first stream may be supplied to a reforming reactor in which coking has occurred for the purpose of regenerating the reforming catalyst in which coke has been deposited, either selectively or sequentially, but the supply of hydrocarbon gas and water vapor may be blocked.

As an example, the synthesis gas production system may further include a carbon dioxide separation unit (30) located after the reforming reaction unit (20). Unreacted carbon dioxide included in the synthesis gas produced through the reforming reaction unit (20) can be separated and captured through the carbon dioxide separation unit (30).

Referring to Fig. 3, a synthesis gas stream and a high-concentration carbon dioxide stream are generated in a carbon dioxide separation unit (30). Among these, the carbon dioxide stream can be resupplied to a reforming reactor (240) to be reused as a reaction raw material or to remove coke deposited on a reforming catalyst.

At this time, it goes without saying that the carbon dioxide stream can be re-supplied to not only one reforming reactor (240) but also to another reforming reactor (210 to 230).

Hereinafter, the continuous operation method for producing synthesis gas according to the present invention will be described in more detail through examples. However, the following examples are only a reference for explaining the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless otherwise defined, 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. The terminology used in the description herein is only for the purpose of effectively describing particular embodiments and is not intended to be limiting of the invention.

(Example 1)

A commercial catalyst (Ni 15 wt%) containing nickel supported on an alumina support was introduced into a laboratory-scale small-scale reforming reactor, and methane gas and carbon dioxide were supplied at a molar ratio of 1:1 to perform a dry reforming reaction under the following reaction conditions.

Catalyst layer reaction temperature: 800 ℃

Weight hourly space velocity (WHSV): 24L/h g

Reaction pressure: Atmospheric pressure (0 barg)

The concentrations of methane, carbon dioxide, and carbon monoxide in the synthesis gas produced through the reaction were monitored in real time using a thermal conductivity detector (TCD) of a gas chromatograph.

Afterwards, when the differential pressure (ΔP _t ) at the inlet and outlet of the catalyst bed became 0.2 barg, the supply of methane gas was stopped and only carbon dioxide was supplied to start the regeneration of the catalyst. At this time, the differential pressure (ΔP _i ) at the inlet and outlet of the catalyst bed measured immediately after the start of the reforming reaction was 0.18 barg.

After the catalyst regeneration began, when the concentration of carbon monoxide became less than 5 mol %, methane gas and carbon dioxide were supplied again to continuously perform the dry reforming reaction.

(Example 2)

The same procedure as Example 1 was followed, except that catalyst regeneration was started when the differential pressure (ΔP _t ) at the inlet and outlet of the catalyst bed became 0.25 barg.

(Example 3)

The same procedure as Example 1 was followed, except that catalyst regeneration was started when the differential pressure (ΔP _t ) at the inlet and outlet of the catalyst bed became 0.35 barg.

(Example 4)

The same procedure as in Example 1 was followed, except that the carbon dioxide was separated and captured from a mixed gas containing synthesis gas produced by a dry reforming reaction and unreacted carbon dioxide, and then reused.

(Comparative Example 1)

The same procedure as Example 1 was followed, except that water vapor was supplied instead of carbon dioxide for catalyst regeneration.

(Comparison of catalyst regeneration efficiency and synthesis gas production efficiency)

FIG. 4 is a drawing showing the results of catalyst regeneration performed according to Example 1, and FIG. 5 is a drawing showing the change in CO concentration according to catalyst regeneration time. As shown in FIG. 5, it can be seen that catalyst regeneration occurs effectively.

During the catalyst regeneration process, coke reacts with the injected carbon dioxide to become carbon monoxide, and monitoring the concentration of carbon monoxide reveals that coke is no longer removed over time.

In Example 1, when only carbon dioxide is injected in the catalyst regeneration mode, it was confirmed that the amount of carbon monoxide produced was significantly reduced (detected carbon monoxide concentration: approximately 5 mol%) for approximately 6 minutes after the start of the regeneration mode, and the detected carbon monoxide concentration after approximately 7 minutes was confirmed to be maintained at a constant level of approximately 1 mol% or less.

In Examples 1 and 2, it was observed that the catalyst regeneration efficiency and synthesis gas production efficiency were the best, whereas in the case of Comparative Example 1, the catalyst regeneration efficiency was slightly better, but the synthesis gas production efficiency was the worst. It is judged that this is because when the catalyst is regenerated using steam, the regeneration of the catalyst proceeds relatively quickly, but the activity is reduced due to oxidation of the catalyst, thereby reducing the synthesis gas production efficiency.

In addition, in the case of Example 2, the time required for catalyst regeneration slightly increased to about 8 minutes compared to Example 1, but in the case of Example 3, the time required for catalyst regeneration was observed to increase rapidly to about 30 minutes. This is believed to be because when the start of catalyst regeneration is delayed, the amount of coke deposited on the catalyst increases, resulting in a rapid decrease in catalyst regeneration efficiency.

Although the present invention has been described with reference to specific matters, limited examples, and drawings, these have been provided only to help a more general understanding of the present invention, and the present invention is not limited to the above examples, and those skilled in the art will appreciate that various modifications and variations may be made from this description.

Therefore, the idea of the present invention should not be limited to the described embodiments, and all things that are equivalent or equivalent to the claims described below as well as the same are included in the scope of the idea of the present invention.

Claims (15)

A first mode for producing a synthesis gas including hydrogen and carbon monoxide discharged from an outlet of the multi-tubular reforming reactor by supplying a hydrocarbon gas stream including methane and a first stream containing carbon dioxide to the inlet of a multi-tubular reforming reactor in which each reforming catalyst is positioned; and
A second mode for blocking the hydrocarbon gas stream and selectively or sequentially supplying the first stream to at least one reforming reactor of the multi-tubular type to regenerate the reforming catalyst in which coke is deposited;
While the second mode is being performed, the hydrocarbon gas stream and the first stream are continuously supplied to another reforming reactor so that the first mode is continuously operated.
The above second mode is a continuous operation method for producing synthesis gas that starts when the following condition 1 is satisfied.
(Condition 1)
ΔP _t > 1.1 x ΔP _i
(ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the beginning of the first mode being performed.) delete In the first paragraph,
The above second mode is a continuous operation method for producing synthesis gas, which is terminated when any one or more of the following conditions 1 to 3 are satisfied.
Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900℃.
Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)
Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less. In the first paragraph,
The above first mode is a continuous operation method for producing synthesis gas by supplying an additional steam stream. In paragraph 4,
A continuous operation method for producing synthesis gas, wherein a dry reforming reaction in which hydrocarbon gas is reformed by reacting it with carbon dioxide in the above-mentioned reforming reactor or a combined reforming reaction in which hydrocarbon gas is reformed by reacting it with carbon dioxide and water vapor simultaneously occurs. In paragraph 5,
A continuous operation method for producing synthesis gas in which the molar ratio of hydrocarbon gas:carbon dioxide supplied to a reforming reactor for the above dry reforming reaction is 1:1 to 2. In paragraph 5,
A continuous operation method for producing synthesis gas, wherein the molar ratio of hydrocarbon gas:steam supplied to a reforming reactor for the above complex reforming reaction is 1:0.1 to 1.5. In the first paragraph,
A continuous operation method for producing synthesis gas, wherein the above reforming catalyst comprises at least one transition metal selected from iron (Fe), aluminum (Al), nickel (Ni), chromium (Cr), palladium (Pd), rhodium (Rh), and platinum (Pt). In the first paragraph,
A continuous operation method for producing synthesis gas in which the coke deposited in the second mode is removed by a reverse Boudouard reaction. In the first paragraph,
A continuous operation method for producing synthesis gas, wherein the regeneration of the above-mentioned reforming catalyst is performed at a temperature of 500 to 900°C. A raw material supply unit in which a first stream containing a hydrocarbon gas stream and carbon dioxide, which are independent raw materials, are independently supplied through a supply pipe; and
A reforming reaction unit including a multi-tubular reforming reactor, each of which is equipped with a reforming catalyst;
The above raw material is supplied to the inlet of the reforming reactor through the supply pipe connected to each reforming reactor, and a synthesis gas containing hydrogen and carbon monoxide is produced, which is discharged through the outlet of the reforming reactor.
It is characterized in that the first stream is supplied to at least one reforming reactor, and the supply of raw materials other than the first stream to the reforming reactor is blocked to regenerate the reforming catalyst in which coke is deposited, while the raw materials are continuously supplied to another reforming reactor.
A synthesis gas production system in which the start of the regeneration of the reforming catalyst in which the coke is deposited is controlled by the following conditional expression 1, and the end of the regeneration of the reforming catalyst is controlled by at least one factor selected from the following conditions 1 to 3.
(Condition 1)
ΔP _t > 1.1 x ΔP _i
(ΔP _t in Conditional Equation 1 is the pressure difference (P _inlet - P _outlet ) measured at the inlet and outlet of each multi-tubular reforming reactor after the first mode is performed for an arbitrary time (t), and ΔP _i is the pressure difference at the inlet and outlet of each multi-tubular reforming reactor measured at the beginning of the first mode being performed.)
Condition 1: The maximum temperature of the catalyst layer of the above reforming reactor exceeds 900℃.
Condition 2: ΔP _t < 1.01 x ΔP _i (ΔP _t and ΔP _i are the same as those in Condition 1 above)
Condition 3: The concentration of carbon monoxide discharged from the outlet of the above reforming reactor is 5 mol% or less. delete In Article 11,
The above raw material supply unit is a synthesis gas production system that supplies raw material including additional steam. In Article 11,
A synthesis gas production system further comprising a carbon dioxide separation unit positioned at the rear end of the reforming reaction unit to separate and capture unreacted carbon dioxide. In Article 14,
A synthesis gas production system that re-supplies the separated and captured carbon dioxide to at least one reforming reactor of the reforming reaction unit to produce synthesis gas or regenerate a reforming catalyst on which coke has been deposited.