KR100980591B1 - A mesoporous nickel-alumina co-precipitated catalyst, preparation method thereof and production method of hydrogen gas by steam reforming of liquefied natural gas using said catalyst - Google Patents

Abstract

PURPOSE: A mesoporous nickel-alumina co-precipitated catalyst is provided to obtain high conversion ratio of liquefied natural gas and hydrogen gas in a steam reforming reaction of the liquefied natural gas without deactivation for a long term and to obtain excellent catalyst activity and stability. CONSTITUTION: A method for preparing a mesoporous nickel-alumina co-precipitated catalyst comprises the following steps: manufacturing a solution including an aluminum precursor and a nickel precursor; manufacturing a nickel-aluminum composite slurry by putting nickel and aluminum to an alkali solution having pH 7 ~ 10 at 0.001 - 0.1 mole/hr and co-precipitating the solution; obtaining nickel-aluminum composite powder through washing, filtering, and drying processes after fermenting the nickel-aluminum composite slurry; and plasticizing the nickel-aluminum composite powder.

Description

MEAPOROUS NICKEL-ALUMINA CO-PRECIPITATED CATALYST, PREPARATION METHOD THEREOF AND PRODUCTION METHOD OF HYDROGEN GAS BY STEAM REFORMING OF LIQUEFIED NATURAL GAS USING SAID CATALYST}

The present invention relates to a medium-porous nickel-alumina co-precipitation catalyst, a method for producing the same, and a method for producing hydrogen by steam reforming of liquefied natural gas using the catalyst, and more particularly, hydrogen by steam reforming of liquefied natural gas. It is used for gas production, and is prepared by coprecipitation of an aluminum precursor and a nickel precursor solution in an alkaline solution having a pH of 7 to 10, characterized in that the atomic ratio of nickel / aluminum is in the range of 0.01 to 1 and the average pore size is in the range of 2 to 10 nm. The present invention relates to a medium porosity nickel-alumina co-precipitation catalyst, a method for producing the same, and a method for producing hydrogen by steam reforming of a liquefied natural gas using the catalyst.

Hydrogen energy is drawing attention as a sustainable energy that can replace existing fossil fuels. Accordingly, research on the widespread use of hydrogen energy has been continuously conducted [M. Schrope, Nature, Vol. 414, 682 (2001)]. In particular, research on the commercialization of Polymer Electrolyte Membrane Fuel Cell (PEMFC), which can produce electric energy using hydrogen energy as a raw material, has been conducted in various fields such as factories, transportation vehicles, and residential power generators. It is actively progressing toward the application to the field. However, in order to commercialize the polymer electrolyte fuel cell, it is essential to develop a catalytic process capable of producing and supplying high purity hydrogen gas stably and efficiently.

Typically, hydrogen gas is known to be produced through reforming reactions using hydrocarbons and alcohols as main raw materials, depending on the type of reactants used with the main raw materials. Rostrup-Nielsel, J. Sehested, J.K. Norskov, Adv. Catal., Vol. 47, 65 (2002)], Auto-thermal Reforming [T. Takeguchi, S.-N. Furukawa, M. Inoue, K. Eguchi, Appl. Catal. A, Vol. 204, p. 223 (2003)], Partial Oxidation [P. Kim, Y. Kim, H. Kim, I.K. Song, J. Yi, Appl. Catal. A, Vol. 272, p. 157 (2004)] and Carbon Dioxide Reforming (Korean Patent No. 394,076). Among these reforming reactions, the composition of the reaction raw materials is simpler than other reactions, so that the design of the reaction equipment is easy and the stable operation for a long time is possible, and the steam reforming reaction of methane, which is superior in the selectivity of hydrogen finally obtained, is performed in commercial hydrogen gas. It is mainly used for production.

Liquefied natural gas, consisting of lower gas such as methane and ethane, has a much higher global reserve than other fossil raw materials, extremely low sulfur content and easy transportation and storage. It has been used as an effective raw material for the industry and various transportation methods. Recently, the gas pipe network developed in large cities has been attracting attention as an effective raw material for producing and supplying hydrogen to fuel cells attached to various vehicles and household generators.

However, in order to stably produce and supply high quality and high purity hydrogen gas for a long time, it is important to select and develop a steam reforming catalyst system which is suitable for steam reforming of liquefied natural gas and at the same time very active. Research on the development of high efficiency reforming catalysts for steam reforming of liquefied natural gas has been conducted continuously.

As catalysts for the reforming reaction for hydrogen gas production, noble metal catalyst systems such as Pt, Pd, Ru and Ir and non-noble metal catalysts such as nickel are known, but since the noble metal catalyst system has a very low price competitiveness, non-noble metal catalyst systems are commercially available. It is widely used in the process. However, nickel-based catalyst has a disadvantage in that it does not show stable activity for a long time due to serious deactivation problems due to poisoning by sulfur, carbon deposition and sintering of catalyst in reforming reaction [Q. Ming, T. Healey, L. Allen, P. Irving, Catal. Today, Vol. 77, 51 (2002)]. In order to overcome the shortcomings of these nickel-based catalysts, commercial processes introduce severe reaction conditions that supply high temperature, high pressure, and excess water vapor, which are not only economically inexpensive, but also small and mobile hydrogen gas whose stability is very important. The application itself is not possible for processes for production. Therefore, it is necessary to design and develop a nickel-based catalyst having high activity and stability at the same time in a large-scale and small-scale steam reforming reaction, that is, a catalyst having a physical chemical structure that is highly resistant to catalyst deactivation.

 In order to increase the stability of the nickel-based catalyst, a small amount of alkali-based or alkaline earth metal-based metals have been added to the nickel-based catalyst to increase the resistance to sintering of nickel particles, but the overall reaction activity is reduced. [JS Lisboa, D.C.R.M. Santos, F.B. Passos, F.B. Noronha, Catal. Today, Vol. 101, p. 15 (2005)]. In addition, although ceria and zirconia have been reported to increase the resistance to carbon deposition by supporting the carrier, these carriers have a limit in cost competitiveness compared to the general alumina carrier [Korea Patent No. 336,968 / Korea Patent No. 858,924. number]. On the other hand, the present inventors have prepared a nickel-supported catalyst having a medium pore structure by the sol-gel method or the casting method (Templating Method) to increase the dispersion of nickel metal particles on the surface of the nickel catalyst in the steam reforming reaction It has been reported that it is possible to suppress the polymerization reaction of surface carbon species and to promote the vaporization reaction, resulting in stable and high reaction activity [JG Seo, M.H. Youn, K.M. Cho, S. Park, I.K. Song, J. Power Sources, Vol. 173, 943 (2007) /J.G. Seo, M.H. Youn, S. Park, J.C. Jung, P. Kim, J.S. Chung, I.K. Song, J. Power Sources, 186, p. 178 (2009) / Korean Patent No. 883,790]. However, in order to prepare a medium-porous nickel-supported catalyst using the sol-gel method or the casting method, an expensive alkoxide precursor, an excess of structural derivatives and alcohol solvents harmful to the human body are used. There is a problem. Therefore, it is necessary to develop a nickel-supported catalyst for steam reforming reaction of highly active liquefied natural gas having a well-developed medium pore structure while reducing process cost. As a result of intensive efforts, the present inventors produced a medium-porous nickel-alumina co-precipitating catalyst having a high reproducibility while reducing manufacturing costs by using a simple, safe and inexpensive precursor because there are no harmful additives. The present invention has been completed by the successful application to hydrogen gas production through steam reforming of gas.

The technical problem of the present invention is a medium-porous nickel-alumina co-catalyst and a method for producing the same, which are stable for a long time due to very high resistance to carbon deposition and particle sintering in hydrogen gas production by steam reforming of liquefied natural gas. To provide.

Another object of the present invention is to provide a method for stably producing a high concentration of hydrogen gas from liquefied natural gas using the catalyst.

In order to achieve the above technical problem, the present invention is used in the production of hydrogen gas by the steam reforming reaction of liquefied natural gas, prepared by coprecipitating the aluminum precursor and nickel precursor solution in an alkaline solution of pH 7 to 10, nickel / aluminum It provides a medium porosity nickel-alumina co-catalyst, characterized in that the atomic ratio of is in the range of 0.01 to 1 and the average pore size is in the range of 2 to 10nm.

The present invention also provides a medium-porous nickel-alumina co-catalyst, characterized in that the aluminum precursor and the nickel precursor solution is incorporated in the alkaline solution at a rate in the range of 0.001 to 0.1 mole / hr based on nickel and aluminum, respectively. do.

In addition, the present invention iii) after preparing the aluminum precursor and the nickel precursor solution so that the atomic ratio of nickel / aluminum is in the range of 0.01 to 1, respectively, at a pH in the range of 0.001 to 0.1 mole / hr based on nickel and aluminum at pH 7 to 10 Preparing a nickel-aluminum composite slurry by coprecipitation by introducing into an alkaline solution in a range; Ii) aging the nickel-aluminum composite slurry for 25 to 100 ^° C. for 1 to 24 hours, followed by washing, filtration and drying to obtain a nickel-aluminum composite powder; Iii) it provides a method for producing a medium-porous nickel-alumina co-catalyst comprising the step of firing the nickel-aluminum composite powder.

In addition, the present invention, the aluminum precursor is aluminum nitrate nonahydrate (Aluminum Nitrate Nonahydrate), aluminum fluoride trihydrate (Aluminum Fluoride Trihydrate), aluminum phosphate hydrate (Aluminum Phosphate Hydrate), aluminum chloride hexahydrate (Aluminum Chloride Hexahydrate), At least one member selected from the group consisting of aluminum hydroxide, aluminum sulfate hexadecahydrate and aluminum ammonium sulfate dodecahydrate, and the nickel precursor is nickel nitrate Nickel Nitrate Hexahydrate, Nickel Chloride Hexahydrate, Nickel Acetate Tetrahydrate, and Nickel Bromide High Rate (Nickel Bromide Hydrate) mesopores, characterized in that at least one member selected from the group consisting of sex nickel provides a method for producing an alumina coprecipitated catalyst.

In order to achieve another object of the present invention, another aspect of the present invention is liquefied natural in the volume ratio of 1/10 to 1/1 at a reaction temperature of 500-900 ℃ in the presence of the medium-porous nickel-alumina co-precipitation catalyst It provides a method for producing hydrogen by the steam reforming reaction of liquefied natural gas (LNG), characterized in that for reacting the mixed gas consisting of gas / steam at a flow rate of 1,000-500,000 ml / g-catalyst, h.

According to the present invention, the medium-porous nickel-alumina co-precipitation catalyst showed high conversion rate of liquefied natural gas and concentration of hydrogen gas in dry gas without deactivation for a long time in the steam reforming reaction of liquefied natural gas, and prepared by similar precipitation method. Compared to the nickel-supported catalyst by the general impregnation method, the medium-sized porous alumina carrier showed excellent catalytic activity and stability.

Hereinafter, the present invention will be described in detail.

The medium-porous nickel-alumina co-precipitation catalyst of the present invention is used to produce hydrogen gas by steam reforming of liquefied natural gas, and is prepared by coprecipitation of an aluminum precursor and a nickel precursor solution in an alkaline solution having a pH of 7 to 10. , The atomic ratio of nickel / aluminum is in the range of 0.01 to 1 and the average pore is in the range of 2 to 10nm.

In the medium-porous nickel-alumina co-catalyst of the present invention, the atomic ratio of nickel / aluminum is preferably 0.01 to 1 in terms of catalytic activity and the economical aspect of catalyst production. When the atomic ratio of nickel / aluminum is 0.01 or less, the nickel active point Not only is it too dilute to be undesirable, but it is not preferable because nickel is so strongly bonded to the structure of alumina in the finally obtained catalyst that it does not function as an active point. Not only is it uneven, but the interaction between nickel and alumina is so weak that it is not preferable because the nickel particles have very low resistance to sintering and carbon deposition. In addition, the medium porosity nickel-alumina co-catalyst of the present invention is formed with an average pore size in the range of 2 to 10nm. The average pore size is determined by controlling the rate of introducing the aluminum precursor and the nickel precursor solution into the alkaline solution.

In the medium-porous nickel-alumina co-catalyst of the present invention, each of the aluminum precursor and the nickel precursor solution is prepared so that the atomic ratio of nickel / aluminum is in the range of 0.01 to 1, and then independently 0.001 to 0.1 mole based on nickel and aluminum. preparing a nickel-aluminum composite slurry by coprecipitation by introducing into an alkaline solution in a pH range of 7 to 10 at a rate in a range of / hr; Ii) aging the nickel-aluminum composite slurry for 25 to 100 ^° C. for 1 to 24 hours, followed by washing, filtration and drying to obtain a nickel-aluminum composite powder; Iii) it may be prepared by a method comprising the step of firing the nickel-aluminum composite powder.

The aluminum precursor may include aluminum nitrate nonahydrate, aluminum fluoride trihydrate, aluminum phosphate hydrate, aluminum chloride hexahydrate and aluminum hydroxide. Representative known water soluble aluminum precursors such as Aluminum Hydroxide, Aluminum Sulfate Hexadecahydrate, and Aluminum Ammonium Dodecahydrate are all available, but Aluminum Nitrate Nonahydrate Is preferred. In addition, nickel precursors also include all of the water-soluble nickel precursors such as nickel nitrate hexahydrate, nickel chloride hexahydrate, nickel acetate tetrahydrate, and nickel bromide hydride. Although available, nickel nitrate hexahydrate is preferred.

In addition, in the present invention, alkali solutions are representatively known basic solutions such as ammonia solution, sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution and sodium carbonate solution which can induce precipitation of aluminum precursor and nickel precursor. More preferred is an aqueous ammonia solution that does not contain other metal components that may affect it. In addition, in the coprecipitation step, it is preferable to continuously supply the base in proportion to the amount of the aluminum precursor and the nickel precursor to maintain the pH.

In addition, in the present invention, the coprecipitation step, the process of aging, washing, filtration, drying and firing is not particularly limited except for controlling the input rate of the precursor solution, it is usually in the art Anyone skilled in the art can perform the method through a generally known method in an appropriate range, so no detailed description will be made herein.

The present invention also provides a mixed gas consisting of liquefied natural gas / water vapor having a volume ratio in the range of 1/10 to 1/1 at a reaction temperature of 500-900 ° C. in the presence of a medium-porous nickel-alumina co-precipitation catalyst. The present invention provides a method for producing hydrogen gas from liquefied natural gas by reacting with flowing in ml / g-catalyst.h. The steam reforming reaction is performed while flowing the liquefied natural gas and steam together with a carrier gas (nitrogen) while maintaining the reactor temperature at 500-900 ° C. At this time, if the reaction temperature is less than 500 ° C, sufficient catalytic activity is achieved. Unexpectedly, when it is 900 degreeC or more, stability by the sintering of a catalyst falls, etc., and is unpreferable. In addition, it is preferable to pass the catalyst layer with the volume ratio of the liquefied natural gas / water vapor to 1/10 to 1/1. If the volume ratio of the liquefied natural gas / water vapor as a reactant is less than 1/10, sufficient activity can be expected. If the volume ratio exceeds 1/1, it is not preferable in terms of energy efficiency.

The method for producing hydrogen gas preferably further includes a pretreatment step of reducing the catalyst charged in the reactor before the reaction into a mixed gas of nitrogen and hydrogen. In general, in the steam reforming reaction of liquefied natural gas, since the active phase is a reduced nickel species, not nickel oxide species, it is preferable that all nickel catalysts undergo a pretreatment process of reducing with hydrogen before performing the reaction. The mixed gas used in the pretreatment is preferably a volume ratio of hydrogen / nitrogen of 1/10 to 1/2. If the volume ratio is less than 1/10, sufficient reduction is not achieved. It is not economical because it exceeds the amount of.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only intended to illustrate the invention and should not be construed as limiting the scope of the invention by these examples.

Preparation Example 1 Preparation of Medium Porosity Nickel-Alumina Coprecipitation Catalyst

First, a small amount of aqueous ammonia solution is added to 50 ml of distilled water, and the solution is stirred at room temperature while maintaining the pH value of 9. Meanwhile, 5 g of aluminum nitrate nonahydrate (manufactured by Sigma-Aldrich) and 0.678 g of nickel nitrate hexahydrate (manufactured by Sigma-Aldrich) are dissolved in another 40 ml of distilled water. The solution obtained in the above step is slowly injected into the distilled water solution having a pH of 9 at a rate of 0.0015 mole / hr based on nickel and aluminum, wherein an aqueous ammonia solution is used to induce precipitation of the dissolved aluminum precursor and the nickel precursor. Was injected at a rate of 20 ml / hr to maintain the pH of the entire solution to 9 and then stirred for 12 hours at room temperature to precipitate the precipitate solution. The aged precipitate solution is washed and centrifuged three times to obtain a light blue precipitate from which unreacted material and aqueous ammonia solution are removed. Thereafter, the precipitate obtained in the step is naturally dried at room temperature for 3 days to remove the solvent contained in the precipitate to obtain a dried powder, and then calcined at 700 ^o C for 5 hours using an electric furnace to finally form a medium porosity A nickel-alumina coprecipitation catalyst was obtained. The catalyst thus obtained was named Ni-Al ₂ O ₃ .

Preparation Example 2 Preparation of Pure Medium Porosity Alumina

For comparison with the medium porosity nickel-alumina co-precipitation catalyst prepared in Example 1, (preparation), a pure medium porosity alumina carrier containing no nickel was first prepared in a similar manner to Preparation Example 1. To this end, a small amount of aqueous ammonia solution is added to 50 ml of distilled water and stirred at room temperature while maintaining the pH value of the solution at 9. Meanwhile, 5 g of aluminum nitrate nonahydrate (manufactured by Sigma-Aldrich) is dissolved in another 40 ml of distilled water. The solution obtained in the above step is slowly injected at a rate of 0.0015 mole / hr based on aluminum to the distilled water solution having a pH of 9, wherein 20 ml / hr of aqueous ammonia solution is used to induce precipitation of the dissolved aluminum precursor. After injecting at a rate to maintain the pH of the entire solution to 9, the precipitated solution was stirred at room temperature for 12 hours to mature the precipitation solution. The aged precipitate solution is washed and centrifuged three times to obtain a white precipitate free of unreacted and aqueous ammonia solution. Then, the precipitate obtained in the step is naturally dried at room temperature for 3 days to remove the solvent contained in the precipitate to obtain a dried powder, and then calcined at 700 ^o C using an electric furnace for 5 hours to finally include nickel A pure mesoporous alumina carrier was obtained. The carrier thus obtained was named Al ₂ O ₃ .

Preparation Example 1 Preparation of Nickel Catalyst Supported on Pure Medium Porosity Alumina Carrier

Nickel was impregnated into the Al ₂ O ₃ carrier prepared in Comparative Example 1 by the general impregnation method. Of 0.996 in distilled water at 1 ml g To this end, nickel nitrate hexahydrate (Nickel Nitrate Hexahydrate, Sigma-Aldrich product) were thoroughly dissolved, which are uniformly mixed so that the sufficient impregnation take place into the Al ₂ O ₃ substrate of 1 g I went through the process. After the above process, the resultant was dried in an oven at 100 ° C. for 24 hours and then heat-treated at 700 ° C. for 5 hours to finally obtain a nickel catalyst supported on a pure mesoporous alumina carrier. The nickel supported catalyst thus prepared was named Ni / Al ₂ O ₃ .

Analysis Example 1 Nitrogen Adsorption and Desorption and Pore Characteristics

1 is a medium porosity nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared by Example 1 of (Preparation) of the present invention, a medium pore alumina carrier prepared by Comparative Example 1 (Al ₂₎ The results of nitrogen adsorption and desorption curves and pore size distribution of the nickel catalyst (Ni / Al ₂ O ₃ ) supported on the mesoporous alumina carrier prepared in Comparative Example 2 (O ₃ ) and (Preparation) are shown. It can be seen that all the prepared carriers and catalysts exhibit IV-type adsorption and desorption curves and H2-type hysteresis phenomenon in typical mesoporous materials. From this, the nickel catalyst supported on the medium-porous alumina carrier (Al ₂ O ₃ ) and the medium-porous alumina carrier for comparison with the medium-porous nickel-alumina co-precipitation catalyst (Ni-Al ₂ O ₃ ) prepared by the present invention (Ni / Al ₂ O ₃ ) all can be confirmed that the material having a medium porosity in accordance with the intention of the present invention. However, if you look closely at the adsorption and desorption tendency can see a big difference. Although Ni-Al ₂ O ₃ and Al ₂ O ₃ are manufactured through the same process except for the inclusion of a nickel precursor at the time of preparation, it can be seen that they exhibit completely different adsorption and desorption curves and pore size distributions. That is, Ni-Al ₂ O ₃ is Al ₂ O ₃ and Ni / Al ₂ O ₃ in the well as much greater amount of adsorption and desorption of nitrogen per unit weight, relative pressure hysteresis occurs also Ni-Al ₂ O ₃ Al ₂ than It can be seen that it is higher than O ₃ . From this, it can be guessed that Ni-Al ₂ O ₃ has better specific surface area and larger pore size than Al ₂ O ₃ and Ni / Al ₂ O ₃ .

Analysis Example 2: Physical and Chemical Properties

Table 1 shows Ni-Al ₂ O ₃ (Preparation Example 1), Al ₂ O ₃ (Preparation Example 1) and Ni / Al ₂ O ₃ (Preparation Example 2) according to the present invention. Physical and chemical properties are shown. Since the Ni / Al atomic ratios of Ni-Al ₂ O ₃ and Ni / Al ₂ O ₃ were approximately similar to 0.17 and 0.18, respectively, the chemical composition of Ni / Al ₂ O ₃ for comparison with Ni-Al ₂ O ₃ according to the present invention. It can be seen that there is no big difference in configuration. However, as previously predicted, Ni-Al ₂ O ₃ shows better specific surface area, pore volume, and pore size than Ni / Al ₂ O ₃ . This can be interpreted as the precipitated alumina stabilized due to the close interaction between the nickel precursor and the aluminum precursor during the precipitation process, resulting in the formation of a mesoporous material having excellent physical properties. On the other hand, Ni / Al ₂ O _{3 It} can be seen that the specific surface area and pore volume is smaller and the pore size is larger than that of the carrier Al ₂ O ₃ , which is consistent with the typical results of the nickel catalyst prepared by the impregnation method. In other words, it can be interpreted that some pores of the mesoporous alumina are blocked by nickel particles during the impregnation process.

Ni-Al ₂ O ₃
(Manufacture) Example 1 Al ₂ O ₃
((Manufacture) Comparative Example 1) Ni / Al ₂ O ₃
((Manufacture) Comparative Example 2) Ni / Al atomic ratio 0.17 - 0.18 Specific surface area (m ² g ^-1 ) 240 228 148 Pore Volume (cm ³ g ^-1 ) 0.46 0.33 0.22 Average pore size (nm) 5.4 4.1 4.3

Analysis Example 3: X-ray Diffraction Characteristics

2 is a medium porosity nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared in Example 1 of the present invention (Me-Al ₂ O ₃ ), a medium porosity alumina carrier prepared in Comparative Example 1 (Al ₂ X-ray diffraction analysis graph of the nickel catalyst (Ni / Al ₂ O ₃ ) supported on the medium-porous alumina carrier prepared in Comparative Example 2 (O ₃ ) and (Preparation) 2 is shown. First, it can be seen that pure Al ₂ O ₃ exhibits characteristic peaks of typical gamma-alumina. In both Ni-Al ₂ O ₃ and Ni / Al ₂ O ₃ , the (440) diffraction peak (dotted line) of the alumina can be found to move at a low angle, which is in close contact with the alumina through the precipitation or impregnation process and the firing process. This is due to the formation of a stable nickel-aluminate phase by incorporation of the nickel particles, which are interacting with each other, into a lattice of alumina. Characteristically, Ni-Al ₂ O ₃ does not develop characteristic peaks corresponding to nickel oxide species, whereas Ni / Al ₂ O ₃ corresponds to nickel oxide species (solid line) at 37, 43, 63 and 76 degrees, respectively. A characteristic peak is found. This is because, unlike Ni / Al ₂ O ₃ , nickel oxide species on Ni—Al ₂ O ₃ are evenly dispersed to a size of 2 nm or less, which is a detection limit of XRD analysis. That is, it can be predicted that the dispersion degree of nickel species in the Ni-Al ₂ O _{3 according} to the present invention is higher than that of Ni / Al ₂ O ₃ for comparison.

Analysis Example 4: Physical and Chemical Properties of Reduced Supported Catalysts

When the Ni-Al ₂ O ₃ and Ni / Al ₂ O ₃ are calcined in a reducing atmosphere at a high temperature to reduce nickel oxide species in the catalyst to nickel metal, the difference in the physical and chemical properties of the nickel species on each catalyst can be examined. The results are shown in Table 2. In order to analyze the physicochemical properties, each catalyst was reduced in a hydrogen atmosphere at 700 ^° C. for 3 hours, and the amount of hydrogen gas adsorbed at 50 ^° C. was measured. Based on the amount of hydrogen adsorbed, nickel dispersion and nickel surface area were calculated under the assumption that H / Ni _s = 1, that is, one hydrogen atom chemically adsorbed onto one active nickel particle. As can be seen from Table 2, it can be seen that the amount of hydrogen adsorption of Ni-Al ₂ O ₃ is much higher than that of Ni / Al ₂ O ₃ . Therefore, it can be seen that Ni-Al ₂ O ₃ is also superior to Ni / Al ₂ O ₃ in terms of nickel dispersion and nickel surface area. From this, the Ni-Al ₂ O ₃ (manufacturer 1) catalyst according to the present invention was compared to the Ni / Al ₂ O ₃ (manufacturer 2) catalyst for comparison. It can be inferred that it is a stable catalyst having a very high resistance to it.

Ni-Al ₂ O ₃
(Manufacture) Example 1 Ni / Al ₂ O ₃
((Manufacture) Comparative Example 2) Hydrogen adsorption amount (μmoleg-catalyst ^-1 ) 12.7 7.8 Nickel Dispersion (%) 0.6 0.3 Nickel Specific Surface Area (m ² g ^-1 ) 4.1 2.0

Analysis Example 5: Temperature Reduction Characteristics of Supported Catalysts

These chemical property differences can be proved more specifically through Temperature-Programmed Reduction (TPR). 3 is a nickel supported on the mesoporous nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared in Example 1 of the present invention and the mesoporous alumina prepared in Comparative Example 2 The temperature reduction test (TPR) result of the catalyst (Ni / Al ₂ O ₃ ) is shown. Ni-Al ₂ O ₃ and Ni / Al ₂ O ₃ catalysts were filled in a U-shaped quartz tube for a temperature reduction test (TPR), followed by mixing with nitrogen (20 ml / min) and hydrogen (2 ml / min). Hydrogen gas consumption was measured according to the temperature by flowing the gas while reducing the temperature while increasing the temperature at a rate of 5 ^o C / min. It can be seen that the reduction peaks are developed at 820 ^o C and 770 ^o C, respectively, in Ni-Al ₂ O ₃ and Ni / Al ₂ O ₃ , due to the reduction of the nickel-aluminate phase described above with reference to FIG. 2. However, it is characteristic that another reduction peak is shown around 580 ^° C. for Ni / Al ₂ O ₃ . This may be due to the reduction of the bulk nickel oxide species which does not interact weakly or with alumina. These bulk nickel oxide species are easily sintered in the reduction process, leading to a decrease in active surface area as shown in Table 2 above. Overall, it can be seen that the mesoporous nickel-alumina co-precipitation catalyst according to the present invention has excellent physical and chemical properties compared to the nickel catalyst supported on the mesoporous alumina for comparison.

Example 1: Characteristics of Steam Reforming of Liquefied Natural Gas Using Medium Porosity Nickel-Alumina Coprecipitation Catalyst

(Manufacturing) A hydrogen gas production reaction was carried out by steam reforming of liquefied natural gas composed of a mixed gas of methane and ethane using the catalysts prepared by the methods of Example 1 and Comparative Example 2. The liquefied natural gas, consisting of a mixture of methane and ethane used as reactants, consisted of 92% methane and 8% ethane. After the catalyst was charged into the reactor for steam reforming, the catalyst was reduced for 3 hours with a mixed gas of nitrogen (30 ml) and hydrogen (3 ml) at 700 ° C. before the reaction, and then the reaction was continuously passed through the catalyst layer in the reactor. This was allowed to proceed. The space velocity of the reactants was maintained at 27,000 ml / h · g-catalyst, and the volume ratio of the reactant LNG / water vapor was maintained at 0.5. Steam reforming of liquefied natural gas was carried out at 600 ° C. The conversion rate of the liquefied natural gas and the composition of the hydrogen gas in the dry gas were respectively calculated by the following equations (1) and (2).

(Equation 1)

(Equation 2)

Figure 4 is a medium porosity nickel-alumina catalyst prepared by (Production) Example 1 of the present invention according to the reaction time (Mea-porous alumina catalyst (Ni-Al ₂ O ₃ ) and (medium) prepared by Comparative Example 2 This is a result showing the change of liquefied natural gas conversion rate of the nickel catalyst (Ni / Al ₂ O ₃ ) supported on. It is noteworthy that the two catalysts tend to be quite different. Ni-Al ₂ O ₃ catalysts show a relatively stable LNG conversion for about 1000 minutes of reaction time, whereas Ni / Al ₂ O ₃ catalysts not only have low activity from the beginning of the reaction, but also carbon as the reaction time elapses. It can be seen that it is rapidly deactivated due to deposition reaction and sintering of nickel particles. The difference in the reaction activity can be attributed to the fact that the Ni-Al ₂ O ₃ catalyst has better physicochemical properties than the Ni / Al ₂ O ₃ catalyst as described above. First, it can be explained that the internal material transfer is easy on the Ni-Al ₂ O ₃ catalyst having a relatively large pore volume and a large pore size, resulting in high reaction activity. In addition, it can be said that nickel species, which are relatively highly dispersed on the Ni-Al ₂ O ₃ catalyst and strongly interact with alumina, effectively suppressed the causes of deactivation such as carbon deposition and sintering of nickel particles.

5 is a medium porosity nickel-alumina catalyst prepared by (Production) Example 1 of the present invention according to the reaction time and a medium porosity alumina prepared by Comparative Example 2 (Ni-Al ₂ O ₃ ) This is the result showing the change of composition of hydrogen gas in dry gas of nickel catalyst (Ni / Al ₂ O ₃ ) supported on. The change in the composition of hydrogen gas in the dry gas can also be confirmed that the same as the change in the conversion rate of the liquefied natural gas shown in FIG. That is, it can be seen that a relatively high purity hydrogen gas can be stably produced through the Ni-Al ₂ O ₃ catalyst according to the present invention.

In conclusion, the mesoporous nickel-alumina co-catalyst (Ni-Al ₂ O ₃ ) according to the present invention may have very good physicochemical properties compared to the nickel catalyst (Ni / Al ₂ O ₃ ) supported on the mesoporous alumina carrier. In addition, it can be seen that it shows superior reaction activity in the steam reforming reaction of liquefied natural gas, from which it can be seen that the medium-sized porosity nickel-alumina catalyst is very effective as intended in the present invention.

The embodiments of the present invention described above should not be construed as limiting the technical idea of the present invention. The protection scope of the present invention is limited only by the matters described in the claims, and those skilled in the art can change and change the technical idea of the present invention in various forms. Therefore, such improvements and modifications will fall within the protection scope of the present invention, as will be apparent to those skilled in the art.

1 is a medium porosity nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared by Example 1 of (Preparation) of the present invention, a medium pore alumina carrier prepared by Comparative Example 1 (Al ₂₎ O ₃₎ and (manufacturing) the comparison result showing a nitrogen adsorption-desorption curve and pore size distribution of the nickel catalyst (Ni / Al ₂ O ₃₎ supported on a porous medium produced by the example 2 alumina

2 is a medium porosity nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared in Example 1 of the present invention (Me-Al ₂ O ₃ ), a medium porosity alumina carrier prepared in Comparative Example 1 (Al ₂ O ₃₎ and (Ltd.) Comparative X- ray diffraction analysis of the nickel catalyst (Ni / Al ₂ O ₃₎ supported on a porous medium produced by the example 2 alumina results

3 is a nickel supported on the mesoporous nickel-alumina catalyst (Ni-Al ₂ O ₃ ) prepared in Example 1 of the present invention and the mesoporous alumina prepared in Comparative Example 2 Result of Temperature-Programmed Reduction (TPR) of Catalyst (Ni / Al ₂ O ₃ )

Figure 4 is a medium porosity nickel-alumina catalyst prepared by (Production) Example 1 of the present invention according to the reaction time (Mea-porous alumina catalyst (Ni-Al ₂ O ₃ ) and (medium) prepared by Comparative Example 2 Graph of Change in LNG Conversion Rate of Nickel Catalyst Supported on Ni / Al ₂ O ₃

5 is a medium porosity nickel-alumina catalyst prepared by (Production) Example 1 of the present invention according to the reaction time and a medium porosity egg prepared by Comparative Example 2 (Ni-Al ₂ O ₃ ) Graph of Changes in Composition of Hydrogen Gas in Dry Gas of Nickel Catalyst (Ni / Al ₂ O ₃ ) Supported on Lumina

Claims (5)

It is used to produce hydrogen gas by steam reforming of liquefied natural gas, It is prepared by coprecipitation of an aluminum precursor and a nickel precursor solution in an alkaline solution in the pH range of 7 to 10, the medium-porous nickel- characterized in that the atomic ratio of nickel / aluminum is in the range of 0.01 to 1 and the average pore size is in the range of 2 to 10nm. Alumina co-catalyst. The method of claim 1, The aluminum precursor and the nickel precursor solution are each independently incorporated into the alkaline solution at a rate in the range of 0.001 to 0.1 mole / hr based on nickel and aluminum, the medium porosity nickel-alumina co-catalyst.  Iv) the aluminum precursor and the nickel precursor solution are prepared so that the atomic ratio of nickel / aluminum is in the range of 0.01 to 1, respectively, and then independently of the nickel and the aluminum at a rate of 0.001 to 0.1 mole / hr. Preparing a nickel-aluminum composite slurry by co-precipitation by adding to an alkaline solution; Ii) aging the nickel-aluminum composite slurry for 25 to 100 ^° C. for 1 to 24 hours, followed by washing, filtration and drying to obtain a nickel-aluminum composite powder; Iii) a method for preparing a medium porosity nickel-alumina co-catalyst comprising calcining the nickel-aluminum composite powder. The method of claim 3, wherein The aluminum precursor may be aluminum nitrate nonahydrate, aluminum fluoride trihydrate, aluminum phosphate hydrate, aluminum chloride hexahydrate, aluminum hydroxide Aluminum Hydroxide, Aluminum Sulfate Hexadecahydrate and Aluminum Ammonium Sulfate Dodecahydrate.At least one selected from the group consisting of, and the nickel precursor is nickel nitrate hexahydrate (Nickel Nitrate). Hexahydrate, Nickel Chloride Hexahydrate, Nickel Acetate Tetrahydrate and Nickel Bromide Hydrate ide Hydrate) medium-porous nickel-alumina co-catalyst production method characterized in that at least one member selected from the group consisting of. A mixed gas consisting of liquefied natural gas / water vapor having a volume ratio in the range of 1/10 to 1/1 at a reaction temperature of 500-900 ° C. in the presence of the medium-porous nickel-alumina co-precipitation catalyst according to claim 1 or 2. A method for producing hydrogen by steam reforming of liquefied natural gas (LNG), characterized by reacting while flowing at 500,000 ml / g-catalyst.h.

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