KR100892033B1 - High surface area spinel structured nano crystalline sized ymgo (1-y) al2o3-supported nano-sized nickel reforming catalysts and their use for producing synthesis gas from combined steam and carbon dioxide reforming of natural gas - Google Patents

Abstract

Nano-sized nickel based reforming catalysts dipped in ymgo(1-y)Al2O3 having a nano-sized crystalline of high surface area spinel structure is provided to improve caulk resistivity, catalyst stability and catalyst activation by performing a complex reforming reaction of steam - carbon dioxide about natural gas. Nano-sized nickel based reforming catalysts dipped in ymgo(1-y)Al2O3 having a nano-sized crystalline of high surface area spinel structure is used for manufacturing synthetic gas consisting of hydrogen and carbon monoxide from natural gas by complex reforming of steam and carbon dioxide. The nickel based reforming catalysts have spinel structure of which grain size is 20 nm or less.

Description

Nickel-based reforming catalyst supported by nanoscale on XYMG (1-xy) As2O₃ with nanosized crystals with high surface area spinel structure and method for producing synthesis gas from natural gas by steam-carbon dioxide complex reforming using the same spinel structured nano crystalline sized ＭＭＯＯ (1-ｙ) Ａｌ2Ｏ3-supported nano-sized nickel reforming catalysts and their use for producing synthesis gas from combined steam and carbon dioxide reforming of natural gas}

The present invention relates to a nickel-based reforming catalyst supported by nanoscale on yMgO (1-y) Al ₂ O ₃ having a nanosized crystal having a high surface area spinel structure, and the synthesis gas from natural gas by steam-carbon dioxide complex reforming using the same. The present invention relates to a manufacturing method, and more particularly, to a nickel-based reforming catalyst by preparing nickel-modified catalyst on yMgO (1-y) Al ₂ O ₃ having a nanosized crystal having a high surface area spinel structure, and preparing a nickel-based reforming catalyst. By performing the steam-carbon dioxide reforming reaction on natural gas under certain reaction conditions, Fischer-Tropsch is controlled by controlling the ratio of hydrogen to carbon monoxide by improving the coke resistance, catalyst stability and catalytic activity compared to conventional steam reforming catalysts. Or it relates to a method for producing a synthesis gas that can be applied to the methanol production reaction.

Steam reforming, which produces a mixture of hydrogen and carbon monoxide, that is, syngas, by reacting steam and natural gas on a catalyst, is an important basic process in the chemical industry. Synthetic gas produced by the steam reforming process of natural gas is the basis of C1 chemistry and is applied to the process of producing methanol, hydrogen, ammonia and the like. Recently, a method of synthesizing liquid fuel through synthesis gas production from natural gas (Gas to liquid: GTL) has emerged as an important method of using natural gas. At this time, it is important to control the ratio of hydrogen to carbon monoxide in the synthesis gas to make a 2: 1 ratio of hydrogen to carbon monoxide suitable for the Fischer-Tropsch process for synthesizing liquid fuel from the synthesis gas.

In general, in the steam reforming process of natural gas, prevention of catalyst deactivation by carbon deposition of reforming catalyst is pointed out as the most important problem. Therefore, in the steam reforming process of natural gas, excess steam is added to prevent catalyst deactivation by carbon deposition. However, in the reforming reaction in which excess water vapor is added, the water gasification reaction is promoted to obtain a synthesis gas having a hydrogen-to-carbon monoxide ratio of 3: 1 or more.In addition to the synthesis gas process for producing ammonia or hydrogen requiring high hydrogen content, Fischer It is not suitable for the synthesis of Tropsch or methanol. That is, one of the drawbacks of steam reforming to produce syngas is that the synthesis gas produced from steam reforming is reduced to gasoline and steam because it limits the molar ratio of hydrogen to carbon monoxide of the syngas mixture produced stoichiometrically to 3: 1 or more. There are limitations in the application to Fischer-Tropsch synthesis, which can produce various hydrocarbons such as diesel fuel and olefins. It is also inadequate to provide a syngas mixture for application to oxygen-containing compound production processes such as hydroformylation and carbonylation.

Thus, in order to synthesize a variety of compounds required by applying the synthesis gas, it is necessary to prepare a synthesis gas having a high content of carbon monoxide, and various research results related thereto have been reported. For example, carbon dioxide reforming and oxygen reforming reactions of methane using carbon dioxide or oxygen instead of steam used as oxidants to diversify the synthesis gas ratio have attracted attention in the 1990s [J. R. Rostrup-Nielsen, Stud. Surf. Sci. Catal., 81, 25 (1993)]. Recently, a complex reforming reaction using water vapor and carbon dioxide at the same time has been published [Q.-H. Zhang et al., Catal. Today 98, 601 (2004)]. Zhang et al. Reported that nanoscale Ni / ZrO2 catalysts were applied to steam-carbon dioxide reforming to control the ratio of hydrogen to carbon monoxide from 1 to 3. According to the reaction results of the paper, methane conversion was 80-90% at methane reference space velocity of about 12,000 ml / (gcat-h) at 800 ℃, but methane conversion was about 60% and space velocity was 36,000 at space velocity of 24,000. Methane conversion was about 40%.

3CH4 + 2H2O + CO2 → 8H2 + 4CO [1]

In the case of the steam-carbon dioxide reforming reaction of natural gas according to Scheme 1, an appropriate synthesis gas (H2 / CO = 2) can be obtained by appropriately adjusting the ratio of water vapor and carbon dioxide as a feed to prepare Fischer-Tropsch or methanol. It has the advantage that it can be used suitably for reaction.

In particular, all of the above-described steam-carbon dioxide reforming process of natural gas has an advantage of easy process control and easy scale-up by endothermic reaction. In contrast, the oxygen reforming process or the autothermal reforming process using oxygen as a reactant includes an exothermic reaction, which makes it difficult to control the process and has a risk of explosion, making it difficult to scale up.

As a catalyst of the steam-carbon dioxide reforming reaction, a nickel catalyst and a noble metal catalyst can be used similarly to the steam reforming reaction of natural gas. However, in this case, catalyst deactivation by coke deposition has been pointed out as the biggest problem of methane reforming reaction.

In particular, since steam cannot be used in the steam-carbon dioxide reforming reaction differently than the steam reforming reaction, if a commercially available nickel catalyst is used as the steam reforming catalyst, catalyst deactivation by coke may occur seriously.

On the other hand, a precious metal supported catalyst can be presented as a high activity catalyst in which coke formation is not a problem. For example, Japanese Patent Laid-Open No. 2000-104078 uses a precious metal supported catalyst such as ruthenium or rhodium. However, the supported precious metal catalysts have better coke resistance and activity than nickel-based catalysts, but they are generally unsuitable for industrial use because they are expensive.

Therefore, there is a need to newly develop a nickel-based catalyst that is economical and has strong carbon deposition resistance. On the other hand, the Korean patent (Registration No .: 10-0482646) is a co-precipitation method to obtain a precipitate produced by mixing the source material of Zr, Ce and Ni in a predetermined molar ratio and stirring under heating conditions and adding an aqueous alkali solution It has been shown that the prepared catalyst is suitable for producing synthesis gas for Fischer Tropsch synthesis reaction by reforming natural gas to carbon dioxide, oxygen, water vapor or a mixture thereof. However, since Zr and Ce source materials are also expensive and are not commonly used carriers, there is a disadvantage in that the formation of the catalyst is difficult.

Examples of using nickel as the active ingredient and magnesium and aluminum oxide as the carrier can be found in commercial steam reforming catalysts. In particular, Haldor-Topsoe supplies Ni / MgAl2O4 catalysts as commercial steam reforming catalysts. However, as mentioned earlier, commercial steam reforming catalysts are not suitable for the steam and carbon dioxide complex reforming reactions pursued by the present invention because they are optimized under conditions using excess steam. In addition, an example in which a catalyst composed of Nix / MgyAl using a precursor having a pseudohydrotalcite structure is used for liquefied petroleum gas (LPG) steam reforming reaction is disclosed in Korean Patent Publication No. 10-2007-0043201. It is limited only to the desite structure and the target reaction is also limited to the liquefied petroleum gas steam development reaction.

Therefore, there is a need to newly develop a catalyst suitable for steam-carbon dioxide composite reforming by optimizing the physical properties of the carrier and the active material nickel.

An object of the present invention for solving the above problems is to provide a reforming catalyst having a nano-sized crystal size with high resistance to carbon deposition and excellent activity and stability compared to conventional commercial reforming catalyst.

Another object of the present invention is to provide a method for preparing a synthesis gas for Fischer-Tropsch and methanol synthesis by applying the prepared catalyst to the combined reforming reaction of water vapor and carbon dioxide.

The present invention, which achieves the object as described above and the problem to remove the conventional defects, synthesizes a yMgO (1-y) Al ₂ O ₃ carrier having a nano-sized crystal having a high surface area spinel structure to nano-nickel It is characterized in that it provides a method for producing a synthesis gas for Fischer-Tropsch and methanol synthesis by applying a new catalyst supported by size and a nickel catalyst having a nano-sized crystal size to a combined reforming reaction of water vapor and carbon dioxide. .

More specifically,

The present invention is a nickel-based reforming catalyst used to prepare a synthesis gas composed of hydrogen and carbon monoxide from natural gas by a complex reforming of water vapor and carbon dioxide,

BET surface area of the carrier is in the range of 50 ~ 150 m ² / g and has a spinel structure having a crystal size of 20 nm or less, and a nano-size having a crystal size of 20 nm or less of the active ingredient nickel is represented by the following formula (1) It is achieved by providing a nano-sized nickel-based reforming catalyst on yMgO (1-y) Al ₂ O ₃ having a nanosized crystal having a high surface area spinel structure.

[Formula 1]

xNi / yMgO (1-y) Al ₂ O ₃

In Formula 1, x represents wt% of Ni in the catalyst, y represents wt% of MgO in the carrier, x is in the range of 6 to 35%, and y is limited to the range of 15 to 35%.

In the present invention, the above catalyst is reduced on a catalyst treated with hydrogen or a mixed gas containing hydrogen at a temperature of 400 to 1,000 ° C, the reaction temperature of 600 to 1000 ° C, the reaction pressure of 0.5 to 30 atmospheres, and the space velocity of 1,000 to A reformed gas composed of steam and carbon dioxide having a molar ratio of water vapor to natural gas in the range of 0.1 to 1.9 and a molar ratio of carbon dioxide to natural gas under a condition of 1,500,000 h ^-1 to reform the natural gas or methane Steam-carbon dioxide composite using a nickel-based reforming catalyst nanoscale-supported on yMgO (1-y) Al ₂ O ₃ having nanoscale crystals with a high surface area spinel structure, characterized in that it produces a synthesis gas composed of carbon monoxide and carbon monoxide. It is achieved by providing a method for producing syngas from natural gas by reforming.

In addition, the present invention provides a reaction molar ratio of water vapor to natural gas in the range of 0.1 to 1.9 on natural gas under the conditions of reaction temperature 600 to 1000 DEG C, reaction pressure 0.5 to 30 atm, space velocity of 1,000 to 1,500,000 h- ¹ . The nano-scale crystal of the high surface area spinel structure is characterized by producing a synthesis gas composed of hydrogen and carbon monoxide by reforming natural gas or methane with a reforming gas composed of steam and carbon dioxide having a reaction molar ratio of 0.1 to 1.9. Eggplant is achieved by providing a method for producing syngas from natural gas by steam-carbon dioxide complex reforming using a nickel-based reforming catalyst nano-supported on yMgO (1-y) Al ₂ O ₃ .

The present invention outperforms the performance of commercial reforming catalysts. Nickel-based reforming catalysts according to the present invention have a novel high surface area spinel carrier (carrier surface area> 50 m2 / g, carrier crystal size <20 nm). A reforming catalyst in which nickel is dispersed in a crystal size of 20 nm or less, and when used to produce a synthesis gas composed of hydrogen and carbon monoxide from natural gas by a complex reforming of water vapor and carbon dioxide, it exhibits excellent resistance to carbon deposition. It is an invention that has a catalytic activity of stability and uses a cheap nickel catalyst at a low price compared to precious metals, and thus is a very effective and useful invention in terms of economics, and is expected to be used industrially.

Hereinafter, the configuration and the operation of the embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the nickel-based reforming catalyst used to prepare a synthesis gas composed of hydrogen and carbon monoxide from natural gas by the combined reforming of water vapor and carbon dioxide, yMgO (1-y) Al ₂ O ₃ having nano-sized crystals used as a carrier. The MgO content is 15 ~ 35wt%, the BET surface area is 50 ~ 150 m ² / g and has a spinel structure with a crystal size of 20 nm or less, the active size of nickel has a crystal size of 20 nm or less It is characterized by a catalyst represented by the following formula (1) having a nano-size.

[Formula 1]

xNi / yMgO (1-y) Al ₂ O ₃

In Formula 1, x represents wt% of Ni in the catalyst, y represents wt% of MgO in the carrier, x is in the range of 6 to 35%, and y is limited to the range of 15 to 35%.

The reason for limiting the MgO content in the yMgO (1-y) Al ₂ O ₃ having a nano-size crystals used as a carrier in the range of 15 to 35wt% is as follows. If the content of MgO is less than 15%, coke formation is advantageous because the acid point of alumina, which is a solid acid, is too high in the carrier, and if the content of MgO exceeds 35%, the interaction between nickel and the carrier is weakened, resulting in coke formation Because it goes well.

The reason for limiting the specific surface area of the carrier to 50 to 150 m ² / g is because the nickel cannot be dispersed well when the specific surface area is less than 50 m ² / g, so that the crystal size of nickel is less than 20 nm As a result, the formation of coke is advantageous as it is not controlled, and if the specific surface area exceeds 150 m ² / g, the stability of the catalyst is inhibited due to catalyst deactivation by catalyst sintering during high temperature catalytic reaction.

In addition, the reason for limiting the carrier crystal size to 20 nm or less is because the crystal size of nickel is controlled to 20 nm or less only when such conditions are maintained to have high activity and stability with high resistance to coke.

The nickel content is limited to 6 to 35%. If the nickel content is less than 6%, the number of active sites is small and high activity cannot be expected. If the nickel content is more than 35%, nickel is unnecessarily used. This is because it has a disadvantage, and also because the crystal size of nickel exceeds 20 nm is advantageous for coke formation.

In addition, the present invention is a method for producing a synthesis gas composed of hydrogen and carbon monoxide from natural gas by a complex reforming of steam and carbon dioxide using the nickel-based reforming catalyst according to the above, in the nickel-based reforming catalyst, Reaction mole ratio of water vapor in the range of 0.1 to 1.9, CO2 mole ratio to natural gas in the range of 0.1 to 1.9, reaction temperature 600 to 1000 ℃, reaction pressure 0.5 to 30 atm, and space velocity 1,000 to 1,500,000 h ^-1 Synthesis gas production reaction from natural gas by the complex reforming of and carbon dioxide can be carried out.

The reason for limiting the reaction molar ratio of water vapor to natural gas in the reactants in the range of 0.1 to 1.9 and carbon dioxide to natural gas in the range of 0.1 to 1.9 is to properly control the ratio of hydrogen to carbon monoxide in the product. This is because the ratio of hydrogen to carbon monoxide in the product exceeds 3.0 when only natural gas and water vapor are present, and the ratio of hydrogen to carbon monoxide in the product is too low, when only natural gas and carbon dioxide are present in the reactants. Accordingly, by controlling the ratio of natural gas, water vapor, and carbon dioxide in the reactants, the syngas mixture may adjust the composition ratio of hydrogen: carbon monoxide to 1: 2.5 to 2.5: 1.

The reason for limiting the reaction temperature to 600 to 1000 ° C is that the yield of the product is low because the methane conversion rate is lower thermodynamically below 600 ° C, and the material of the reactor is unnecessarily used at a high temperature exceeding 1000 ° C. This is because the economy is inferior because of the use of this special high price.

The reason for limiting the reaction pressure to 0.5 to 30 atm is because heat transfer is not easy at less than 0.5 atm, which leads to an unnecessarily large size of the reactor, which lowers the yield of product per unit volume of the reactor, and when the pressure exceeds 30 atm, This is due to the low conversion of methane due to the thermodynamic nature of the product yield.

And the reason for limiting to the operating conditions of the space velocity 1,000 ~ 1,500,000 h ^-1 is that if the space velocity is less than 1,000 h ^-1 , the processing capacity of the reactants per unit catalyst is too low, and the production of the product per unit catalyst is low, and the space velocity is 1,500,000 If it is more than h ^-1 , heat transfer becomes a problem and the conversion rate of methane drops sharply to obtain a desired product.

In the present invention, the catalyst is reduced by using hydrogen or a mixed gas containing hydrogen at a temperature of 400 to 1,000 ° C., reaction temperature of 600 to 1000 ° C., reaction pressure of 0.5 to 30 atmospheres, and space velocity of 1,000 to 1,500,000. A reformed gas consisting of water vapor and carbon dioxide having a reaction molar ratio of water vapor to natural gas in the range of 0.1 to 1.9 and a molar ratio of carbon dioxide to natural gas under a condition of h ⁻¹ , and reforming natural gas or methane to react with hydrogen. Syngas composed of carbon monoxide can be produced.

In addition, the catalyst may be used by coating or supported on another metal or metal oxide carrier. That is, any metal or metal oxide may be used as long as it is a metal or metal oxide capable of supporting the catalyst of the present invention.

Referring to the present invention in more detail as follows.

As a method for preparing yMgO (1-y) Al ₂ O ₃ having nano-size crystals having a high surface area spinel structure, which is a carrier according to the present invention, a coprecipitation method, precipitation deposition method, sol-gel method, melting method, impregnation method, etc. may be used. As the method of supporting nickel on the carrier, it is preferable to mainly use an incipient wetness method, a melting method, an impregnation method, or the like.

First, a method of preparing a yMgO (1-y) Al ₂ O ₃ carrier having a nano-sized crystal having a high surface area spinel structure is briefly described as follows.

Magnesium nitrate aqueous solution and aluminum nitrate aqueous solution were prepared at 1 M concentration, and then mixed as needed, followed by stirring at 50 to 95 ° C. for 4 to 72 hours, followed by precipitation of 10% aqueous ammonia until pH 10 was added. Let's do it. The precipitate is repeatedly filtered and washed with distilled water. The filtered precipitate was put in a drying oven and dried at 90 to 110 ° C. for 10 to 12 hours, then placed in a kiln and fired at 700 to 900 ° C. for 6 to 12 hours to obtain yMgO having nanoscale crystals having a desired high surface area spinel structure. Obtain a (1-y) Al ₂ O ₃ carrier.

Meanwhile, a method of supporting nickel on a carrier having a high surface area spinel structure will be described based on the incipient wetness method.

Prepare a 1M aqueous solution of nickel nitrate as much as the pore volume of the carrier to meet the desired nickel loading. At this time, when the nickel nitrate aqueous solution is less than the pore volume of the carrier, it is replenished with distilled water in an insufficient amount. Then, the prepared solution is slowly injected into the carrier. If the prepared aqueous solution of nickel nitrate is larger than the pore volume of the carrier, it is first injected as much as the pore volume, and then slowly dried at a temperature of about 50 to 80 ° C. and the remaining solution is repeated. The prepared catalyst precursor powder was put in a drying oven and dried at 90-110 ° C. for 12 hours, and then put in a calcination furnace and fired at 500-800 ° C. for 6 hours in air to obtain a desired nickel-based reforming catalyst.

In addition, the method of supporting the nickel component on the carrier will be explained by the melting method as follows.

In order to support the thin and uniform metal components on yMgO (1-y) Al ₂ O ₃ carriers with nanosized crystals with high surface area spinel structure, the precursors were deposited at or below the firing temperature by using the melting point of nickel metal precursors having low melting point. In order to form a molten mixture, the catalyst and the metal precursor powder to be supported are finely ground and mixed well at room temperature, and then, the metal precursor is decomposed and calcined by an ablation heat treatment to prepare a catalyst. In the heat treatment process, the catalyst precursor powder is placed in a calcination furnace and heated at 2 ° C. per minute from room temperature to 400 ° C. under argon at a flow rate of 100 mL per minute to melt all the nitrates and decompose the nitrates at 400 ° C. for 4 hours, and then dry the gas. After changing to air stream, the temperature was raised from 400 ° C. to 650 ° C. at 5 ° C. per minute and heat-treated at 650 ° C. for 4 hours.

On the other hand, the method of supporting the nickel component on the carrier will be described based on the impregnation method as follows. The carrier powder was added to distilled water, stirred to form a slurry, and then 1M nickel nitrate aqueous solution was added to the slurry so as to meet a desired loading amount and stirred at 25 ° C. for 5 to 7 hours. Then, a flask containing the mixed solution is connected to a rotary vacuum evaporator to evaporate water while rotating at a reduced pressure of 90 to 120 Torr and a temperature of 70 to 90 ° C. The catalyst precursor powder having evaporated water was put in a drying oven, dried at 100 ° C. for 12 hours, put in a kiln, and fired at 500-800 ° C. for 6 hours in air to obtain a desired nickel-based reforming catalyst.

However, the above methods are merely examples of a method for preparing a nickel-based reforming catalyst formed on a yMgO (1-y) Al ₂ O ₃ carrier having a nano-sized crystal having a high surface area spinel structure according to the present invention. In addition to the method exemplified above, another known production method may be suitably applied as necessary.

Using the nickel-based reforming catalyst according to the present invention will be described in more detail the reaction conditions when producing a synthesis gas from natural gas by a complex reforming of water vapor and carbon dioxide as follows.

The new nickel-based reforming catalyst supported on the yMgO (1-y) Al ₂ O ₃ carrier having nanoscale crystals having a high surface area spinel structure is a synthesis gas composed of hydrogen and carbon monoxide from natural gas by complex reforming of water vapor and carbon dioxide. It can be applied to the reforming reaction carried out to produce. In this case, the reaction molar ratio of water vapor to natural gas in the complex reforming reaction is in the range of 0.1 to 1.9, and the reaction molar ratio of carbon dioxide to natural gas is in the range of 0.1 to 1.9.

In addition, the reaction temperature is controlled in the range of 600 ~ 1000 ℃, the reaction pressure is controlled in the range of 0.5 ~ 30 atm, and the reactor gas is injected continuously while controlling the flow rate of the gas so that the space velocity is 1,000 ~ 1,500,000 h ^-1 React to produce synthetic gas.

As described above, the present invention is a conventional nickel reforming catalyst is optimized for steam reforming reaction using an excessive amount of steam, which is not suitable for applying to a reaction for producing a synthesis gas from natural gas by a complex reforming of steam and carbon dioxide. In order to improve the efficiency, the nickel has a crystallite size of 20 nm or less on a carrier having a high surface area spinel structure having a BET surface area of 50 to 150 m ² / g and a crystal size of 20 nm or less (preferably 0.1 to 20 nm). By supporting nano size (preferably 0.1 ~ 20 nm), it has high resistance to carbon deposition in natural gas reforming reaction by combined reforming of water vapor and carbon dioxide, and shows high activity and stability. It is to present the possibility.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on an Example. However, the present invention is not limited only to the following examples.

(Manufacture example 1)

: Preparation of 0.2MgO-0.8Al ₂ O ₃ Carrier Containing 20wt% MgO by Precipitation Method

A 0.2 MgO-0.8Al ₂ O ₃ carrier containing 20 wt% MgO was prepared by the following precipitation method.

First, a 1 M magnesium nitrate aqueous solution and an aluminum nitrate aqueous solution were mixed in the required ratios and stirred vigorously at 60 ° C. for 6 hours. 10% aqueous ammonia (Fisher Scientific) was added thereto until the pH was 10, and the precipitate was filtered and washed with distilled water. The filtered precipitate was put in a drying oven, dried at 100 ° C. for 12 hours, and finely pulverized the dried powder in mortar, and then put in a calcination furnace and fired at 800 ° C. for 6 hours in air to obtain a desired carrier. The BET surface area of the calcined carrier was 110 m 2 / g. At this time, the crystal size of the carrier measured by XRD was 4 nm.

(Manufacture example 2)

: Preparation of 25wt% -Containing 0.25MgO-0.75Al ₂ O ₃ Carrier by Sol-Gel Method

Magnesium nitrate at 1O &lt; 0 &gt; C at 20 DEG C is mixed with a 1M concentration aluminum nitrate solution in a prepared catalyst so that the MgO content is 25wt% and dissolved uniformly for 5 hours. After 6 hours of complete dissolution, the same number of moles of ethylene glycol was added thereto, followed by stirring for 6 hours. Then, the mixed solution was distilled under reduced pressure at 80 ~ 100 ℃ concentrated to a high viscosity state and dried in a microwave oven. As a final step, the dried carrier powder was finely pulverized in mortar and placed in a kiln for 5 hours at 300 ° C. and 6 hours at 900 ° C. in air. The BET surface area of the calcined carrier was 86 m ² / g. At this time, the crystal size of the carrier measured by XRD was 10 nm.

(Manufacture example 3)

: Preparation of 29 wt% -Containing 0.29MgO-0.71Al ₂ O ₃ Carrier by Coprecipitation Method

Magnesium nitrate aqueous solution and aluminum nitrate aqueous solution of 1 M concentration were mixed in the required ratio and stirred vigorously at 80 ° C. for 6 hours. The 10% KOH solution was slowly added drop-wise until pH 10.5, and aged at 80 ° C. for 3 days. The precipitate was filtered and washed with distilled water until K was not detected. . The filtered precipitate was put in a drying oven, dried at 110 ° C. for 12 hours, and finely pulverized the dried powder in mortar, and then put in a calcination furnace for firing at 1000 ° C. for 6 hours in air to obtain a desired carrier. The BET surface area of the calcined carrier was 63 m 2 / g. At this time, the crystal size of the carrier measured by XRD was 17 nm.

(Examples 1 to 3)

Preparation of Ni / 0.2MgO-0.8Al ₂ O ₃ Reforming Catalyst by Incipient Wetness Method

The process of preparing a nickel reforming catalyst by supporting nickel on the 0.2MgO-0.8Al ₂ O ₃ carrier prepared in Preparation Example 1 by using the incipient wetness method is as follows.

First, in a state in which 20 g of the carrier powder is flattened in a crucible, an aqueous nickel nitrate solution corresponding to the pore volume of the carrier (0.5 cm ³ / gx 20 g = 10 cm ³ of the carrier prepared in Preparation Example 1) is slowly added. If the volume of the nickel nitrate solution is larger than the pore volume of the carrier, the solution is first added as much as the pore volume and then dried at 80 ° C., and then the nitrate solution is repeatedly added to the carrier. Then, the flask containing the solution was connected to a rotary vacuum evaporator, and the sample was processed while rotating at a temperature of 100 Torr and a temperature of 80 ° C. In the next step, the catalyst precursor powder was put in a drying oven, dried at 100 ° C. for 12 hours, and then placed in a calcination furnace for firing at 500 ° C. for 6 hours in air to complete the reforming catalyst. The amount of nickel supported was 10 wt% (Example 1), 20 wt% (Example 2), and 30 wt% (Example 3) based on the total weight of the catalyst.

(Examples 4 to 6)

: Preparation of Ni / 0.25MgO-0.75Al ₂ O ₃ Reforming Catalyst by Impregnation

The process of preparing a nickel-modified catalyst by loading nickel on the 0.25MgO-0.75Al ₂ O ₃ carrier prepared in Preparation Example 2 using the impregnation method is as follows.

First, 20 g of carrier powder was added to a 500 mL round bottom flask containing 200 mL of distilled water and stirred to form a slurry. Then, an aqueous solution of nickel nitrate of 1M concentration was added to a desired loading amount at 25 ° C. Stir for time. Then, the flask containing the solution was connected to a rotary vacuum evaporator, and water was evaporated while rotating at a temperature of 100 Torr and a temperature of 80 ° C. The catalyst precursor powder having evaporated water was put in a drying oven, dried at 100 ° C. for 12 hours, and then put in a calcination furnace for firing at 600 ° C. for 6 hours in air to complete a reforming catalyst. The amount of nickel supported was 10 wt% (Example 4), 20 wt% (Example 5), and 30 wt% (Example 6) based on the total weight of the catalyst.

(Examples 7-9)

: Preparation of Ni / 0.29MgO-0.71Al ₂ O ₃ Reforming Catalyst by Melting Method

The process of preparing a nickel reforming catalyst by supporting nickel on a 0.29MgO-0.71Al ₂ O ₃ carrier prepared in Preparation Example 3 using a melting method is as follows.

20 g of the carrier powder and the nickel nitrate hexahydrate corresponding to the desired loading amount are mixed well. At this time, it is good to use a method such as ball-mill to mix uniformly well. In the next step, the catalyst precursor powder was put in a drying oven, dried at 100 ° C. for 12 hours, and then placed in a calcination furnace for 6 hours at 800 ° C. in air to complete the reforming catalyst. The amount of nickel supported was 10 wt% (Example 7), 20 wt% (Example 8), and 30 wt% (Example 9) based on the total weight of the catalyst.

(Comparative Example 1)

: Preparation of 0.12Ni / 0.29MgO-0.71Al ₂ O ₃ Catalyst with Carrier Surface Area of 50 m ₂ / g or Less

The following catalyst was prepared as a comparative catalyst for comparing the catalyst of the present invention with the reforming activity and catalyst stability. First, in Comparative Example 1, a catalyst having the same composition and physical properties as 12% Ni / MgAl ₂ O ₄ (MgO: 29%), which is widely used as a commercial steam reforming catalyst, was prepared by the following method.

A carrier was prepared according to Preparation Example 3, but the firing of the carrier was performed at 1200 ° C. for 6 hours. The BET surface area of the calcined carrier was 15 m 2 / g. At this time, the crystal size of the carrier measured by XRD was 53 nm. A catalyst was prepared in the same manner as in Example 1, but the nickel content of the catalyst was 12 wt%.

(Comparative Examples 2 and 3)

Preparation of 0.12Ni / 0.1MgO-0.9Al ₂ O ₃ Catalyst and 0.12Ni / 0.4MgO-0.6Al ₂ O ₃

The following catalyst was prepared as a comparative catalyst for examining the effect of the MgO content in the carrier on the reforming activity and catalyst stability.

First, a carrier was prepared under the same conditions as Preparation Example 1, but the content of MgO in the carrier was 10wt%. A catalyst was prepared in the same manner as in Example 4, but the content of nickel in the catalyst was 12 wt% (Comparative Example 2). 0.12Ni / 0.4MgO-0.6Al ₂ O ₃ catalyst of Comparative Example ₃ was prepared in the same manner as in Comparative Example 2, but the content of MgO in the carrier was 40wt%.

(Comparative Examples 4 and 5)

: Preparation of 0.5Ni / 0.29MgO-0.71Al ₂ O ₃ Catalyst and 0.4Ni / 0.29MgO-0.71Al ₂ O ₃

The following catalyst was prepared as a comparative catalyst for examining the effect of the Ni content in the catalyst on the reforming activity and catalyst stability.

First, in Comparative Example 4, a carrier was prepared under the same conditions as in Preparation Example 3, and a catalyst was prepared in the same manner as in Example 7, but the nickel content of the catalyst was 5wt%. In Comparative Example 5 was prepared in the same manner as in Comparative Example 4, but the content of nickel in the catalyst was 40wt%.

Experimental Example 1

: Determination of Reforming Activity of Nickel Reforming Catalyst by Steam-Carbon Dioxide Reforming Reaction of Natural Gas

In order to compare the reforming activity of the nickel reforming catalysts of Examples 1 to 9 with the comparative catalysts of Comparative Examples 1 to 5, a steam-carbon dioxide reforming reaction of natural gas was performed. The reforming activity of the catalyst was measured by the following method, and the results are shown in Table 1 below.

A typical fixed bed catalytic reactor manufactured in the laboratory was used for the measurement of catalyst activity. First, the catalyst was pelletized, then pulverized in mortar, and only 60-100 mesh sized catalyst particles were sieved to fill the reactor. Before the reaction, the mixture was reduced with 5% hydrogen at 700 ° C. for 1 hour and then used. As a reactant, a CH ₄ : H ₂ O: CO ₂ ratio was injected into the reactor at a ratio of 1: 0.8: 0.4. Also, to calculate the methane conversion rate, nitrogen was flowed in the same amount as methane as the reference gas. At this time, the temperature of the reactor was controlled in the range of 600 ~ 850 ℃ by an electric heater and a programmable thermostat (Hanyoung Electronics, HY P-100), the space velocity is grams of catalyst, 530,000 cm per hour unless otherwise stated Synthesis gas was prepared by continuously injecting the gas while controlling the flow rate of the gas with a mass flow controller to be ³ . The composition of the gas before and after the reaction was analyzed by a micro gas chromatograph (Agilent 3000) directly connected to the reactor.

The natural gas reforming catalyst was measured at 650 ° C over time to measure the activity and stability at high temperature. The initial activity and the activity after 20 hours were measured by the conversion of methane. The results are shown in Table 1 below. And catalyst stability was measured by the following formula (1).

As shown in Table 1, the catalysts prepared in Examples 1 to 9 are all at 650 ° C., and the catalysts have a CH ₄ : H ₂ O: CO ₂ ratio of 1: 0.8: 0.4 and a space velocity of 530,000 cm ³ / hg. All of the stability was found to be relatively stable with more than 95%. It is actually 3,000 h ^-1 space because the ratio of water vapor and carbon dioxide to methane is 1.2, and the space velocity is 530,000 cm ³ / hg, which is the activity and stability exhibited in poor conditions, which are 150 times faster than the commercial steam reforming process. When applied to speeds, higher methane conversion and stability can be expected.

For reference, in order to confirm the degree of carbon deposition of the used catalyst, the SEM photograph observed after reacting the catalyst of Example 1 for 20 hours is shown in FIG. 1. As can be seen in Figure 1 it can be seen that the catalyst according to Example 1 is produced relatively less carbon.

On the contrary, in the case of Comparative Example 1 having a surface area of 15 m ² / g of carrier and a crystal size of 53 nm of carrier, the initial methane conversion was 49%, and after 20 hours, the catalyst stability was 72%. Low activity and stability.

Therefore, in the case of the complex reforming reaction using water vapor and carbon dioxide, the surface area of the carrier and the crystal size of the carrier are very important, and the surface area and the carrier crystal size of 50 m ² / g and the carrier crystal size of 20 nm or less have to be maintained to have high activity and stability. have. For reference, in order to confirm the degree of carbon deposition of the used catalyst, SEM images observed after reacting the catalyst of Comparative Example 1 for 20 hours are shown in FIG. 2. As can be seen in Figure 2 it can be seen that carbon deposition is very severe when the catalyst used for commercial use in the steam-carbon dioxide complex reforming as it is. Therefore, the catalyst according to the present invention exhibits higher activity and stability than commercially widely used catalysts, suggesting the possibility of replacing existing commercial catalysts.

In Comparative Example 2 having a MgO content of 10 wt% in the carrier, the methane conversion after 20 hours was 88% compared to the initial stage, resulting in less than 90% catalyst stability. For reference, in order to confirm the degree of carbon deposition of the used catalyst, SEM images observed after reacting the catalyst of Comparative Example 2 for 20 hours are shown in FIG. 3. In the case of the catalyst according to Comparative Example 2, it can be confirmed that carbon deposition is severe in the steam-carbon dioxide complex reforming reaction.

Similarly, in the case of Comparative Example 3 having an MgO content of 40 wt% in the carrier, the methane conversion was 87% after 20 hours, and the catalyst deactivation was less than 90%. In order to confirm the degree of carbon deposition of the used catalyst, the SEM photograph observed after reacting the catalyst of Comparative Example 3 for 20 hours is shown in FIG. 4. In the case of the catalyst according to Comparative Example 3, it can be seen that carbon deposition is severe in the steam-carbon dioxide complex reforming reaction.

The catalyst according to Comparative Example 4 had a nickel loading of 5 wt%, and the methane conversion rate after 20 hours had a problem in terms of stability at 73% of the initial stage. This is because the content of nickel, the active ingredient, is low and is easily deactivated over time.

The catalyst according to Comparative Example 5 had a loading of 40 wt% nickel, and thus, the reactor was clogged due to severe carbon deposition at the beginning of the reaction, and thus the steam-carbon dioxide complex reforming reaction could not be performed. Therefore, when the amount of nickel supported is 40wt%, it can be confirmed that it is not suitable for the steam-carbon dioxide complex reforming reaction.

Experimental Example 2

: Reforming activity of nickel catalyst by steam-carbon dioxide reforming reaction of methane at reaction temperature 700 ~ 800 ℃

In this experimental example, the reforming activity was measured at various temperature ranges of the nickel reforming catalysts prepared in Examples 1 to 3, and their activity was measured by the following method.

The same method as in Experimental Example 1 was used to measure the catalytic activity. However, the activity was measured at a reaction temperature of 700 ~ 800 ℃ over time, the initial activity and the activity after 20 hours was measured through the conversion of methane. And catalyst stability was measured by the above-mentioned Formula (1). Table 2 shows the reaction results.

From Table 2, it can be seen that the activity and stability of the reforming catalyst prepared according to the embodiment of the present invention are very excellent at the reaction temperature of 700 ~ 800 ℃. In particular, the methane conversion was almost close to the equilibrium conversion at all temperature conditions, it can be seen that the activity of the catalyst according to the present invention is very high that the equilibrium conversion at the space velocity of 530,000 cm ³ / hg. Compared to the results reported by Zhang et al. In the literature using nano-size Ni / ZrO ₂ catalysts (Catal. Today 98, 601 (2004)), the reaction temperature was 800 ° C. and the methane reference space velocity of 100,000 h ^{−1 was} higher than 96. It showed methane conversion of more than%, which shows very superior catalytic activity compared to the methane conversion of 40% at the same temperature methane-based space velocity of 36,000 h ⁻¹ . On the other hand, the methane conversion after 20 hours was almost the same as the initial conversion, and the catalyst stability was also very high. Therefore, it can be confirmed that the catalyst according to the present invention has high activity and stability at a reaction temperature of 700 ° C. or higher.

Experimental Example 3

: Control of the hydrogen to carbon monoxide ratio in the product according to the change of water vapor to carbon dioxide ratio in the reactants

In the present experimental example, the nickel reforming catalyst prepared in Example 1 was used to change the ratio of water vapor to carbon dioxide in the reactants to control the ratio of hydrogen to carbon monoxide in the product. Catalysis was measured by the following method.

The same method as in Experimental Example 1 was used to measure the catalytic activity. However, the hydrogen to carbon monoxide ratio in the product was measured while changing the ratio of water vapor to carbon dioxide in the reaction at a reaction temperature of 800 ° C. The results are shown in Table 3.

As shown in Table 3, the H ₂ / CO ratio of the product can be controlled by changing the ratio of H ₂ O and CO ₂ as reactants while the ratio of (H ₂ O + CO ₂ ) / CH ₄ is fixed at 1.2. It was confirmed that there is. For example, in the case of carbon dioxide reforming of methane, the H ₂ / CO ratio is about 0.9, and the H ₂ / CO ratio is about 1.5 when water vapor and carbon dioxide are respectively supplied to 0.6 methane. _{H 2 O: CO 2: N} 2: CH 4 = 0.9: 0.3: 1: 1 and _{H 2 O: CO 2: N} 2: CH 4 = 0.8: 0.4: 1: the product between one of the conditions of H ₂ / CO ratios were 2.0 and 2.3 respectively. If only steam reforming was carried out, a H ₂ / CO ratio of 3.3 was obtained, which is the result of the water gas shift reaction (CO + H ₂ O → CO ₂ + H ₂ ) with some excess steam. Therefore, it can be seen that the H ₂ / CO ratio of the product can be controlled through a mixed reforming reaction in which the composition of the reactants is changed using the catalyst according to the present invention to mix the steam reforming reaction and the carbon dioxide reforming reaction.

The present invention is not limited to the above-described specific preferred embodiments, and various modifications can be made by any person having ordinary skill in the art without departing from the gist of the present invention claimed in the claims. Of course, such changes will fall within the scope of the claims.

1 is a SEM photograph after using the catalyst for steam-carbon dioxide reforming according to an embodiment of the present invention,

2 is a SEM photograph of the used catalyst of Comparative Example 1 in the comparative catalyst,

3 is a SEM photograph of the used catalyst of Comparative Example 2 in the comparative catalyst,

4 is a SEM photograph of the used catalyst of Comparative Example 3 in the comparative catalyst.

Claims (6)

In the nickel-based reforming catalyst used to produce a synthesis gas composed of hydrogen and carbon monoxide from natural gas by a complex reforming of water vapor and carbon dioxide, BET surface area of the carrier is in the range of 50 ~ 150 m ² / g and has a spinel structure having a crystal size of 20 nm or less, and a nano-size having a crystal size of 20 nm or less of the active ingredient nickel is represented by the following formula (1) A nickel-based reforming catalyst supported nanoscale in yMgO (1-y) Al ₂ O ₃ having a nanosized crystal having a high surface area spinel structure. [Formula 1] xNi / yMgO (1-y) Al ₂ O ₃ In Formula 1, x represents wt% of Ni in the catalyst, y represents wt% of MgO in the carrier, x is in the range of 6 to 35%, and y is limited to the range of 15 to 35%. The catalyst according to claim 1 is subjected to a reduction treatment using hydrogen or a mixed gas containing hydrogen at a temperature of 400 to 1,000 ° C., reaction temperature of 600 to 1000 ° C., reaction pressure of 0.5 to 30 atmospheres, and space velocity of 1,000 to A reformed gas composed of steam and carbon dioxide having a molar ratio of water vapor to natural gas in the range of 0.1 to 1.9 and a molar ratio of carbon dioxide to natural gas under a condition of 1,500,000 h ^-1 to reform the natural gas or methane Steam-carbon dioxide composite using a nickel-based reforming catalyst nanoscale-supported on yMgO (1-y) Al ₂ O ₃ having nanoscale crystals with a high surface area spinel structure, characterized in that it produces a synthesis gas composed of carbon monoxide and carbon monoxide. Method for producing syngas from natural gas by reforming. On the catalyst according to claim ¹ , the reaction mole ratio of water vapor to natural gas is in the range of 0.1 to 1.9, under the conditions of reaction temperature 600 to 1000 ° C, reaction pressure 0.5 to 30 atm, and space velocity of 1,000 to 1,500,000 h ^-1 . The nano-scale crystal of the high surface area spinel structure is characterized by producing a synthesis gas composed of hydrogen and carbon monoxide by reforming natural gas or methane with a reforming gas composed of steam and carbon dioxide having a reaction molar ratio of 0.1 to 1.9. A method for preparing syngas from natural gas by steam-carbon dioxide complex reforming using a nickel-based reforming catalyst having nanoscale supported on yMgO (1-y) Al ₂ O ₃ . The method of claim 2, The synthesis gas is a method for producing a synthesis gas consisting of hydrogen and carbon monoxide, characterized in that the composition ratio of hydrogen: carbon monoxide is controlled to 1: 2.5 to 2.5: 1. The method of claim 3, wherein The synthesis gas is a method for producing a synthesis gas consisting of hydrogen and carbon monoxide, characterized in that the composition ratio of hydrogen: carbon monoxide is controlled to 1: 2.5 to 2.5: 1. delete

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