KR101245484B1 - Water gas shift catalysts and method for producing syngas by Water gas shift reaction using the same - Google Patents

Abstract

The present invention relates to a catalyst for water gas shift reaction and a method for producing syngas by water gas shift reaction using the catalyst. More specifically, the present invention is for a water gas conversion reaction in which a binary active metal of copper (Cu) and molybdenum (Mo) is supported on a ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier. A catalyst and a method for producing syngas by performing a water gas shift reaction under the catalyst, the catalyst characterized by the present invention is higher than a copper (Cu) mono-based catalyst or a conventional commercial catalyst In addition to maintaining catalyst activity, it has excellent durability against thermal cycling at 250 ° C. or higher, and thus is usefully applied to various fields such as fuel cells, petrochemical processes, and hydrogen stations.

Water gas conversion reaction, fuel reformer, carbon monoxide, hydrogen, vehicle with reformer for fuel cell, heat cycle

Description

Water gas shift catalysts and method for producing syngas by Water gas shift reaction using the same}

The present invention provides a catalyst for a water gas shift reaction in which a ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier is supported by a certain content ratio of a binary active metal of copper (Cu) and molybdenum (Mo), and the catalyst It relates to a method for producing syngas by performing a water gas conversion reaction under.

In the process of reforming fossil fuel, carbon monoxide (CO) is inevitably generated, and carbon monoxide generated during reforming deteriorates fuel cell performance by poisoning platinum used as a cathode catalyst of polymer electrolyte fuel cell (PEMFC). Therefore, a process of removing carbon monoxide is required before supplying reformate gas to the PEMFC stack. Given the effect on the long term performance of the PEMFC stack, it is known that the allowable range of carbon monoxide (CO) concentration in the reformed gas supplied is about 20 ppm or less, preferably 10 ppm or less.

As a method of removing carbon monoxide (CO) in the reformed gas, various reactions such as water gas shift (WGS), selective partial oxidation (PROX) and methanation have been announced. have. Among them, in the fuel reformer for fuel cell vehicle mounting, the method of connecting the WGS reactor and the PROX reactor in order has been studied the most.

The WGS reactor reduces the concentration of carbon monoxide in the reformed gas by about 1% to reduce the load of the PROX reactor and increase the concentration of hydrogen.The PROX reactor selectively oxidizes the carbon monoxide emitted from the WGS to reduce the CO concentration in the reformed gas. It reduces to about 10 ppm or less. In addition, the water gas shift (WGS) reaction consists of a reaction of converting carbon monoxide into water vapor to hydrogen and carbon dioxide, and the reaction formula is as follows.

CO + H ₂ O → CO ₂ + H ₂ ΔH = -40.5 kJ / mol

In this case, the conversion rate of the water gas conversion (WGS) reaction is determined by the temperature and pressure under the control of the equilibrium conversion, and the water gas conversion (WGS) reaction is an exothermic reaction. The reverse reaction proceeds to consume hydrogen to produce carbon monoxide, which is more advantageous under low temperature conditions.

Recently, due to the increased demand for hydrogen in various industries, much attention has been focused on the production of hydrogen by the water gas shift (WGS) reaction, in particular, the production of other compounds using hydrogen, ammonia and syngas. It is also a reaction process that is important in commercial plants.

Hydrogen (H ₂ ) is generally produced with a large amount of carbon monoxide in steam reforming or partial oxidation of hydrocarbons, and carbon monoxide produced as a by-product has an adverse effect by acting as an impurity in many chemical reactions requiring pure hydrogen. For example, in the ammonia synthesis process, carbon monoxide poisons the ammonia synthesis catalyst and poisons the platinum (Pt) cathode catalyst in the polymer electrolyte fuel cell. Thus, the WGS reaction, which lowers carbon monoxide concentration and additionally increases hydrogen production, is an essential chemical reaction process [DS Newsome, Catal. Rev. -Sci. Eng. , 21 (2), (1980) 275].

Reactions associated with such a water gas shift (WGS) reaction include hot water gas shift (HTS), low temperature water gas shift (LTS), and sour gas shift reactions, and if necessary, hot water gas shift (HTS). ) And the low temperature water gas shift (LTS) reaction. At this time, in a general commercial process, the HTS reactor is operated at around 300 to 450 ° C, and the LTS reactor is operated at 200 to 300 ° C.

In detail, the sour gas conversion reaction is a process of converting a raw gas generated by coal or gasification reaction containing sulfur into a liquid fuel by catalytic reaction at around 350 ° C. In the reaction of converting sulfur containing coal (mainly lignite) into liquid fuel as a sour gas conversion reaction, it is more preferable to apply a molybdenum (Mo) catalyst having durability against sulfur. . The Mo-based catalyst is an aqueous solution of ammonium heptamolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O) on a carrier such as Al ₂ O ₃ , MgO, ZnO, Mg-aluminate, Zn-aluminate, or the like. Prepared by impregnating and drying and then calcining at 500 ° C. [X. Xie et al., Appl. Catal ., 77 (1991) 187].

Commercial HTS catalysts contain 8-12 wt% CrO₃With Fe₃O₄Is used as a catalyst, Cr₂O₃Fe₃O₄The sintering does not occur at a high temperature to prevent the reduction of the iron (Fe) surface area. HTS catalysts may also be added with MgO or ZnO to improve selectivity for methane production, sulfur resistance or mechanical strength [A. Andreev et al.,Appl. Catal., 22 (1985) 385.

A commercial LTS catalyst is mainly composed of Cu / Zn, and is generally prepared by coprecipitation using an aqueous solution of sodium carbonate and a metal nitrate compound having an atomic ratio of Cu / Zn of 0.4 to 2 [Yeping Cai et al., US Patent 6,627,572 B1 (2003); G. Petrini et al., Studies in Surface Science and Catalysis , 16 (1983) 735]. Cu / ZnO / Al ₂ O ₃ -based oxide catalysts are most commonly used in the industry, and commercial LTS catalysts (ICI-52-1) developed by ICI are approximately 30 wt% CuO, 45 wt% ZnO and 13 wt% % Al ₂ O ₃ (GW Bridger et al., Catalyst Handbook , ICI, Wolf Scientific Books, (1970) 97).

Meanwhile, researches to develop high performance WGS catalysts have been steadily progressed since the 1960s, and recently, as commercialization of fuel cell vehicles became more visible, many types of WGS catalysts have been announced. Recently, Igarasia Kira et al. Have published a platinum-based WGS catalyst in which platinum is supported on an alumina or zirconia carrier, and when a metal such as rhodium, yttrium, calcium, chromium, lanthanum and ruthenium is added to 3 wt% platinum, It is reported that the effect is enhanced (Korean Patent Registration No. 386,435).

In addition, among the recently released catalysts, Pt, Pd, Cu and Ni supported on CeO ₂ have been attracting much attention because of their excellent activity in the WGS reaction [RJ Gorte et al., Applied Catalysis A : General 258 (2004) 271; Samuel J. Tauster, et al., US Patent 5,139,992 (1992). The reason why the metal catalyst supported on ceria (CeO ₂ ) shows excellent activity in the WGS reaction is that ceria (CeO ₂ ) has high oxygen storage capacity and oxygen mobility.

Gorte et al., In the WGS reaction, carbon monoxide (CO) adsorbed on the metal surface of the catalyst reacts with lattice oxygen of ceria (CeO ₂ ) or oxygen adsorbed on the surface, and ceria (CeO ₂ ) not only retains oxygen well, It is reported to exhibit good activity because of the rapid movement of oxygen.

In addition, research on catalysts for the water gas shift reaction using precious metals has been conducted, for example, X Wang and R.J. Gorte performed the water gas conversion reaction on carbon monoxide while adding various promoters (Fe, Tb, Gd, Y, Sn, Sm, Pr, Eu, Bi, Cr, V, Pb, Mo) to Pd / Ceria. It has been reported that the activity is enhanced when Fe is added as a promoter [X. Wang and R. J. Gort, Appl. catal. A: Gen., 247, 157-162 (2003).

US Patent Publication No. 2002/0141938 A1 reported the results of the WGS reaction on a precious metal supported catalyst prepared by supporting a precious metal selected from Pt, Rh, Ru, and Re in thynia or zirconia. However, precious metal supported WGS catalysts are expensive and have limited use possibilities, and therefore, development of high performance transition metal based WGS catalysts is required. In particular, since the price of fuel reformer is about 20% of the total reforming system based on the performance of the current commercial catalyst and fuel cell, the price and limitation of use of platinum has a significant effect on the economic efficiency of commercialization. It is known to be very large.

According to the US DOE report, using commercial HTS and LTS catalysts, WGS reactors are equivalent to one-third of the volume, weight and price of fuel reformers, so miniaturization of fuel reformers is necessary to commercialize fuel cell vehicle fuel reformers. It is the most important core technology. In particular, commercially available Cu / ZnO / Al ₂ O ₃ -based LTS catalysts undergo greatly deactivation in the oxidizing and reducing atmospheres, and deactivation of the catalyst proceeds. There are weak disadvantages [DJ Moon, JW Ryu, Catal. Letters 92 (1-2) (2004) 17]. Therefore, it is most important to develop high performance WGS catalyst for LTS replacement, which maintains the durability of the catalyst even under the thermal cycling conditions in which oxidation and reduction states are changed, and is more resistant to sulfur and more active than commercial LTS catalyst. It is a core technology.

Recently, the present inventors have proposed a transition metal carbide based WGS catalyst for commercial LTS replacement having durability against thermal cycling [DJ Moon, JW Ryu, Catal. Letters 92 (1-2) (2004) 17; LT Thompson, J. Patt, DJ Moon, C. Phillips, US Patent 6,623, 720 B2] and Pt-Ni / CeO ₂ catalyst [DJ Moon, et al., K Patent 10-2005-0103568 (2005), US Patent 0238574 A1 (2005)], and the developed WGS catalyst was found to have improved durability against thermal cycling than a commercial LTS catalyst.

The present inventors have continually researched to develop a novel catalyst for high performance water gas shift (WGS) reaction. As a result, when a water gas conversion reaction is carried out on a ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier under a catalyst in which copper (Cu) and molybdenum (Mo) binary active metals are supported in a certain content ratio, The present invention was found to be superior to the active catalyst-supported catalyst using a commercial catalyst and a ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier, and to exhibit high activity and durability against thermal cycling. It was completed.

It is an object of the present invention to provide a catalyst for a water gas shift reaction.

Another object of the present invention is to provide a method for preparing a synthesis gas by performing a water gas shift reaction under the above catalyst.

In order to solve the above problems, the present invention has the following features.

The present invention is characterized by a catalyst for water gas shift (WGS) reaction represented by Chemical Formula 1, in which copper (Cu) and molybdenum (Mo) are simultaneously supported as active ingredients on a ceria-zirconia carrier.

Cu-Mo / Ce _x Zr _1-x O ₂

In Formula 1, 0.0001 ≦ x <1.

The present invention also features a catalyst for water gas shift (WGS) reaction in which the weight ratio of copper / molybdenum (Cu / Mo) supported on the carrier as an active ingredient is in the range of 3 to 10.

In addition, the present invention is characterized by a catalyst for the water gas shift (WGS) reaction containing 0.1 to 20% by weight of copper (Cu) based on the support.

In addition, the present invention is characterized by a catalyst for water gas shift (WGS) reaction in which molybdenum (Mo) is contained in an amount of 0.1 to 10% by weight based on the carrier.

In addition, the present invention is a step of preparing a slurry by mixing the precursors of ceria (Ce) and zirconia (Zr) with ultrapure water, respectively; Adding urea (CH ₄ N ₂ O) to the slurry in an amount of 0.1 to 5 mol%, stirring, drying and calcining to prepare a ceria-zirconia carrier; Dissolving and mixing the ceria-zirconia carrier in distilled water to prepare a ceria-zirconia carrier slurry; Dissolving each of the copper (Cu) precursor and the molybdenum (Mo) precursor in ultrapure water to prepare an active metal salt aqueous solution; 5 steps of preparing a catalyst precursor by impregnating the aqueous solution of the active metal salt in the ceria-zirconia carrier slurry; And drying and firing the impregnated catalyst precursor; Characterized in that the method for producing a catalyst for water gas conversion (WGS) reaction represented by the formula (1) comprising a.

In addition, the present invention is a method for producing a synthesis gas prepared by performing a water gas shift (WGS) reaction in the presence of a catalyst represented by the formula (1), the reaction temperature of 200 ~ 450 ℃ and the space velocity of 1,000 to 50,000 h ^-1 It is characterized by.

In addition, the present invention is characterized by a fuel cell vehicle fuel reformer, domestic fuel reformer, polymer electrolyte fuel cell (PEMFC) fuel reformer, a hydrogen station (hydrogen station) or a method for producing a synthesis gas applied to the petrochemical process do.

The catalyst of the present invention is applied to a water gas shift (WGS) process in which carbon monoxide and water vapor are converted to hydrogen and carbon dioxide, thereby having excellent catalytic activity and durability against thermal cycling.

Hereinafter, the present invention will be described in detail.

As a conventional technique, a catalyst for water gas shift reaction in which copper (Cu) or molybdenum (Mo) is supported as an active ingredient on a conventional carrier is known. However, the present invention is characterized in that a binary catalyst, on which copper (Cu) and molybdenum (Mo) are simultaneously supported on a ceria-zirconia carrier, is applied as a catalyst for water gas shift reaction.

That is, in the present invention, copper (Cu) supported by the active metal exhibits excellent activity in hydrogenation or CO conversion, and molybdenum (Mo) has high adsorption strength of oxygen (O ₂ ) and carbon monoxide (CO). The synergistic effect of improving the catalytic activity of (Cu) is given, as well as the effect of increasing the oxygen mobility of the ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier. As a result, compared to a catalyst in which copper (Cu) or molybdenum (Mo) is supported on a conventional carrier alone, it has excellent activity when applied to the WGS reaction.

Referring to the configuration of the catalyst of the present invention in more detail as follows.

The carrier constituting the catalyst of the present invention is ceria-zirconia (Ce _x -Zr _1-x O ₂ ), and the content (x) of ceria contained in the carrier is in the range of 0.0001 ≦ x <1, preferably 0.3 ≦ x ≦ The 0.9 range, particularly preferably, is limited to 0.3 ≦ x ≦ 0.7. In the WGS reaction, carbon monoxide adsorbed on the metal surface of the catalyst reacts with lattice oxygen or oxygen adsorbed on the surface of the catalyst. Therefore, it shows good catalytic activity, and zirconia (Zr) has excellent thermal stability, easy oxygen transport, and plays a role of increasing the dispersibility of the supported metal catalyst, and thus has optimal conditions as a catalyst carrier for the WGS reaction.

In addition, active metals constituting the catalyst of the present invention are copper (Cu) and molybdenum (Mo). Copper (Cu) as the active metal is supported in the range of 0.1 to 20% by weight, preferably 5 to 15% by weight, based on the ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier, and molybdenum (Mo) is 0.1 to 10% by weight, preferably 1 to 3% by weight, particularly preferably 1 to 2% by weight. If the amount of copper (Cu) supported on the ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier is less than 0.1% by weight, the amount is insignificant and the activity is lowered. There is a problem that the durability against thermal cycling (falling) by. When the amount of molybdenum (Mo) supported on the ceria-zirconia (Ce _x -Zr _1-x O ₂ ) carrier is less than 0.1 wt%, it does not affect the catalytic activity. Sintering) is promoted there is a problem that the catalytic activity is lowered. Therefore, it is also important to optimize the loading of copper (Cu) and molybdenum (Mo) in constructing the catalyst of the present invention.

In addition, in the catalyst of the present invention, in order for copper (Cu) and molybdenum (Mo) included as active metals to exhibit optimal activity, it is also important to adjust the weight ratio of these metals to a specific range. That is, the catalyst of the present invention maintains the weight ratio of copper (Cu) / molybdenum (Mo) of 3 or more, preferably 3 to 10, more preferably 5 to 10. The reason is that when copper (Cu) and molybdenum (Mo) in the WGS reaction maintains the proper weight ratio, molybdenum acts as a promoter in the WGS reaction, and the synergistic effect of the active metals causes the optimum catalytic activity and heat and sulfur (Sulfur) This is because it improves durability against).

On the other hand, the present invention also includes a method for producing a catalyst for water gas shift (WGS) reaction represented by the formula (1) in the scope of rights, it will be described in more detail based on the characteristics of the catalyst of the present invention.

The first step is to prepare a slurry by mixing the precursors of ceria (Ce) and zirconia (Zr) in ultrapure water, respectively, in an amount that can satisfy the formula (1).

The mixing of the precursors of ceria (Ce) and zirconia (Zr) is carried out in the range of 20 to 60 ℃, the ultrapure water is used in the range of 100 to 200% by weight relative to the precursor mixture. The precursors of ceria (Ce) and zirconia (Zr) are compounds of the type generally used in the field of catalyst production, and may specifically use oxides, chlorides, nitrates, and are preferably used in the form of nitrates.

In the second step, 0.1 to 5 mol% of urea (CH ₄ N ₂ O) is added to the slurry, followed by stirring, followed by drying and calcining to prepare a ceria-zirconia carrier.

Ceria-zirconia may be _{(Ce x -Zr 1-x O} 2) contains an impurity, it is preferable to perform a pre-treatment with urea prior to use in the catalyst manufacturing process in order to have a larger surface area than a carrier. If the amount of the urea is less than 0.1 mol%, it does not affect the formation of the carrier having a large surface area, and if it exceeds 5 mol%, it is difficult to remove the urea by the post-treatment process. It is better to maintain the above range because a problem arises. The stirring is performed at 70 to 90 ° C. for 3 to 6 hours, and the drying is performed at 100 to 120 ° C. for 12 to 24 hours. In addition, the firing is carried out at room temperature to 400 to 600 ℃ at a temperature increase rate of 5 to 10 ℃ / min under an air atmosphere, and then performed for 2 to 4 hours under an air atmosphere.

In step 3, the ceria-zirconia carrier is dissolved in distilled water and mixed to prepare a ceria-zirconia carrier slurry.

When the distilled water is used in the amount of 50 to 100% by weight based on the carrier, it is preferable to maintain the above range because the drying time increases after impregnation of the active metal salt.

Step 4 dissolves each of the copper (Cu) precursor and the molybdenum (Mo) precursor in ultrapure water in a separate vessel to prepare an aqueous active metal salt solution.

The copper (Cu) precursor and molybdenum (Mo) precursor are generally used in the field of catalyst production, respectively, and are not particularly limited. Specifically, the copper (Cu) precursor and the molybdenum (Mo) precursor may be used in the form of oxides, chlorides, ammonium salts, nitrates, and the like. In addition, ultrapure water is used in the range of 50 to 100% by weight with respect to each precursor, the temperature during the dissolution is preferably maintained at 20 to 60 ℃.

In step 5, the ceria-zirconia carrier slurry is impregnated with each aqueous active metal salt solution to prepare a catalyst precursor.

At this time, the carrier slurry is added dropwise to the aqueous active metal salt solution while stirring under a temperature range of 50 ~ 70 ℃, and then stirred for 3 to 6 hours at 70 ~ 90 ℃ to impregnate the active metal in the carrier.

In step 6, the impregnated catalyst precursor is dried and calcined to prepare a catalyst represented by Chemical Formula 1.

The drying is carried out in a drying oven at 100-120 ° C. for 12 to 24 hours, and the firing is carried out at an elevated temperature rate of 5-10 ° C./min under an air atmosphere to 400-600 ° C. at room temperature, followed by 2 to 2 hours under an air atmosphere. Run for 4 hours.

On the other hand, the present invention includes a step of performing a water gas shift (WGS) reaction under the catalyst represented by Formula 1 prepared above. The reaction conditions affecting the catalytic activity and selectivity of the present invention in the water gas conversion (WGS) process were investigated. The catalysts of the present invention were aqueous at 200 to 450 ° C. and at a reaction rate of 1,000 to 50,000 h ⁻¹ . It is preferable to carry out the gas conversion process. Compared to the conventional water gas conversion process, which is performed in a two-step reaction form of low temperature (220-270 ° C.) and high temperature (350-450 ° C.), it can be performed in a one-step reaction type in the medium temperature region to use a single reactor. As a result, the reactor size can be reduced.

These catalysts are relatively inexpensive as compared to the noble metal catalysts used in the conventional WGS reaction, and have a high enough catalytic activity in the water gas shift reaction as well as durability against thermal cycling.

Therefore, the catalyst according to the present invention can be applied to fuel cell vehicle fuel reformer, polymer electrolyte fuel cell (PEMFC) fuel reformer, hydrogen station (hydrogen station), petrochemical process, in particular gasoline, liquefied petroleum gas (LPG) In addition, the present invention can be variously applied to water gas shift reaction (WGS) to reduce carbon monoxide concentration after performing various hydrocarbon reforming reactions.

Hereinafter, the present invention has been described in more detail based on the following Preparation Examples, Examples and Experimental Examples, but the present invention is not limited to the following Preparation Examples, Examples and Experimental Examples.

Preparation Example Carrier Preparation of Catalyst for Water Gas Conversion Reaction (WGS)

First, a certain amount of cerium nitrate hexahydrate [Cerium nitrate hexahydrate, Ce (NO ₃ ) ₃ ㆍ 6H ₂ O, 99.5%, Acros Organics] and zirconyl oxynitrate hydrate (ZrO (NO ₃ ) ₂ xH ₂ O, 99.99%, Aldrich Chemicals] was dissolved in 60 ° C. ultrapure water to prepare an aqueous solution containing each metal salt. 1 mole of urea [Urea, CH ₄ N ₂ O] was added to each of the aqueous metal salt solutions prepared above, stirred at 60 ° C. for 4 hours, and then completely dried at 110 ° C. for 24 hours in a drying oven. The dried carrier precursor was heated in an air atmosphere at an elevated temperature rate of 5 to 10 ° C./min from room temperature to 500 ° C., and then calcined for 2 hours to prepare a carrier.

Carried out in the same manner as above, but prepared by varying the content of Ce and Zr are shown in Table 1 below. Carrier Preparation Example 7 was prepared by physical mixing of 1: 1 molar ratio of Ce and Zr of CeO ₂ and ZrO ₂ prepared in Carrier Preparation Examples 1 and 6, respectively.

Preparation Example Preparation of Catalyst for Water Gas Conversion Reaction (WGS)

Catalyst Preparation Example 1

Cu-Mo / Ce _0.9 Zr _0.1 O ₂ catalyst described in Table 2 was prepared by the following method.

First, ammonium molybdate tetrahydrate, (NH ₄ ) ₆ Mo ₇ O ₂₄ 4H ₂ O, Dae Jung Chemicals, 99%] and copper nitrate, Cu (NO ₃ ) ₂ ㆍ 3H ₂ O, Shinyo Pure Chemicals, 99%] were dissolved in ultrapure water at 60 ° C., respectively, to prepare aqueous solutions containing respective metal salts.

That to a mixture of carrier Preparation 2 of Ce _0.9 Zr _0.1 O ₂ obtained above was strongly stirred at 60 ℃ for 12 hours and then impregnated with a temperature 110 ℃ in a drying oven to prepare a completely dried catalyst precursor for 24 hours. The dried catalyst precursor was heated in an air atmosphere at an elevated temperature rate of 5 to 10 ° C./min from room temperature to 550 ° C., and then calcined for 4 hours to prepare a catalyst.

Catalyst Preparation Examples 2 to 9 and Catalyst Comparative Preparation Examples 1 to 16

Performed in the same manner as described above, the catalyst prepared by varying the content of Ce and Zr and the content of Cu and Mo is shown in Table 2 below.

(Continued Table 2)

EXAMPLES Water Gas Conversion Reaction (WGS)

The reaction characteristics of the catalyst prepared above were measured in a conventional fixed bed catalytic reaction system consisting of a reactant feed, an evaporator, a WGS reactor, a water trap, and on-line gas chromatography (GC). DJ Moon, JW Ryu, Catalysis Letters 92 (1-2) (2004) 17.

Gas phase reactants such as hydrogen, carbon monoxide and nitrogen were each fed to the reactor in a predetermined amount depending on pretreatment and reaction conditions using a mass flow controller. Liquid reactants such as water were fed to the evaporator using a metering pump (Young Lin Co., model M930), preheated at 150 ° C., and then supplied to the reactor. The evaporator and the WGS reactor used Inconel-600 1/2 inch tube tubes, respectively.

The reaction temperature was measured by attaching a chromel-alumel thermocouple to the inlet and the outlet of the catalyst bed, respectively, and controlling the reaction temperature within a range of ㅁ 1 ° C. using a PID temperature controller. In addition, all lines were heated above 120 ° C. so that moisture in the reaction products did not condense on the lines, and the temperature of each line was sensed and recorded by thermocouple and thermograph.

Example 1

The water gas shift reaction of a mixed gas containing hydrogen (45.2 vol% H ₂ , 37.1 vol% H ₂ O, 6.4 vol% CO ₂ and 11.3 vol% CO) was carried out under the following reaction conditions.

Cu-Mo / Ce _0.9 Zr _0.1 O ₂ catalyst of Preparation Example 1 0.5 g was charged to the catalyst bed of a fixed bed reactor supported by quartz wool, and then the Ar mixed gas containing 5 vol% hydrogen was reduced at 350 ° C. for 3 hours under a flow of 40 cc / min. WGS reaction was carried out while changing the reaction temperature to 200 ~ 340 ℃, and the resulting conversion of CO is shown in Table 3 below.

Moisture contained in the reaction product is removed from the water trap, followed by an on-line gas with a carbosphere column (3.18 ㅧ 10 ^-3 m OD and 2.5 m length) and a thermal conductivity detector (TCD). Analyzed using chromatography [Hewlett Packard Co., HP6890 series].

Examples 2-9 and Comparative Examples 1-10 and 12-16

The same procedure as in Example 1 was carried out, except that the WGS reaction was performed using the catalysts obtained in Catalyst Preparation Examples 2 to 9, Catalyst Comparative Preparation Examples 1 to 10, and Catalyst Comparative Preparation Examples 12 to 16, respectively. The conversion rate of is shown in Table 3 below.

Comparative Example 11

In the same manner as in Example 1, except that Cu-Mo / Ce _0.9 Zr _0.1 O ₂ of Preparation Example 1 using a commercial LTS catalyst Cu-ZnO / Al ₂ O ₃ (Comparative Preparation Example 11) 2 Under the flow of volume% H ₂ and 98 volume% N ₂ mixed gas, the WGS reaction was carried out by reduction at 200 ° C. for 4.5 hours.

Experimental Example 1 Comparison of CO Conversion Rate with Temperature Change in Water Gas Conversion

The following Table 3 shows the CO conversion rate according to the reaction temperature change in the range of 200 to 340 ° C using each catalyst prepared in Preparation Examples 1 to 9 and Comparative Preparation Examples 1 to 16.

1 shows the CO conversion rate according to the temperature change by performing a water gas conversion reaction in Examples 3, 5, 8 and Comparative Examples 1, 4, and 11, among various examples and comparative examples described in Table 3. It is shown. As a result, in the Cu-Mo / Ce _0.5 Zr _0.5 O ₂ catalyst of Examples 3, 5, and 8 according to the present invention, the activity of the catalyst increases as the reaction temperature increases, and the activity of the catalyst is maintained at around 300 ° C. It could be confirmed. Cu / CeO ₂ in Comparative Example 1 was found to be about 300 ° C., and the conversion rate of carbon monoxide (CO) dropped sharply due to deactivation. 10 wt% Cu / Ce _0.5 Zr _0.5 O ₂ of Comparative Example 4 and Cu-Mo / Ce _0.5 Zr _0.5 O ₂ catalysts of Examples 3, 5, and 8 having different amounts of impregnated Cu and Mo as active metals were 280 It showed higher CO conversion in the reaction temperature range in the range of ˜340 ° C. However, the catalyst of Comparative Example 4 has a lower relative activity than Examples 3, 5, and 8, and it can be seen that the activity is somewhat reduced in the high temperature region of 325 ° C or higher.

In addition, Cu-ZnO / Al ₂ O ₃ , a commercial LTS catalyst of Comparative Example 11, had a relatively high catalytic activity in the region of 200 to 260 ° C., but it was confirmed that CO conversion decreased rapidly as the reaction temperature increased. there was.

In addition, Cu-Mo / Ce _0.5 Zr _0.5 O ₂ catalysts of Examples 3, 5, and 8 in which the impregnation amounts of 1 wt% Pt / Ce _0.5 Zr _0.5 O ₂ and the active metals Cu and Mo of Comparative Example 12 were changed In comparison, in the low temperature range in the reaction temperature range from 280 to 300 ° C, high CO conversion was shown. However, in the high temperature region of the reaction temperature of 300 ℃ or more, the activity was somewhat reduced, showing a relatively low activity compared to the Cu-Mo / Ce _0.5 Zr _0.5 O ₂ catalyst of Examples 3, 5 and 8 of the present invention.

In addition, 10 wt% Cu / Ce _0.5 Zr _0.5 O ₂ of Comparative Example 4 exhibited higher CO conversion in the reaction temperature range of 280 to 340 ° C. than the 10 wt% Cu / CeO ₂ / ZrO ₂ catalyst of Comparative Example 13. Seemed. This suggests that the use of ceria-zirconia (Ce _x -Zr _1-x O ₂ ) as the carrier component of the catalyst presented in the present invention has superior activity compared to the use of ceria and zirconia alone or in physical mixing, respectively. Is showing.

In addition, the Cu-Mo / Ce _0.7 Zr _0.3 O ₂ catalyst of Comparative Examples 14 and 15 had a weight ratio of Cu / Mo of 20 and 13, compared to the Cu-Mo / Ce _0.7 Zr _0.3 O ₂ catalyst illustrated in Example 2 As the weight ratio of Mo to Cu is relatively small, the CO conversion rate is low in the reaction temperature range of 280 to 340 ° C. This is also a result of not being able to obtain a synergistic effect because the content of Mo is too low.

In contrast, the Cu—Mo / Ce _0.5 Zr _0.5 O ₂ catalyst of Comparative Example 16 had a Cu / Mo weight ratio of 1 and the Cu—Mo / Ce _0.5 Zr _0.5 O illustrated in Examples 3, 5, 7, 8, and 9 Compared to ₂ catalysts, the content of Mo to Cu is relatively high, indicating a significantly lower CO conversion rate.

According to the results of this Example and Comparative Example, in the case of the catalyst for WGS reaction containing copper (Cu) and molybdenum (Mo) at the same time, when the content of these metals to the carrier and the weight ratio between these metals are optimally maintained, Molybdenum (Mo) acts as a promoter in the WGS reaction and it can be confirmed that the synergistic effect of the active metal can improve the optimum catalytic activity and heat and sulfur resistance (Sulfur).

(Continued Table 3)

Experimental Example 2 Comparison of Long-term Durability of Catalysts in Water Gas Conversion

Water gas of mixed gas (45.2% by volume H ₂ , 37.1% by volume H ₂ O, 6.4% by volume CO ₂ and 11.3% by volume CO) containing hydrogen was tested for the durability of the thermal cycling of the catalyst. The conversion reaction was carried out under the following reaction conditions.

Specifically, 10 wt% Cu-1 wt% Mo / Ce _0.5 Zr _0.5 O ₂ of Example 3, 12 wt% Cu-2 wt% Mo / Ce _0.5 Zr _0.5 O ₂ of Example 8, of Comparative Example 4 10 g of Cu / Ce _0.5 Zr _0.5 O ₂ and 0.5 g of commercial LTS (Cu-ZnO / Al ₂ O ₃ ) catalyst of Comparative Example 11 were charged in a catalyst bed of a fixed bed reactor supported by quartz wool, respectively. After pretreatment of Ar mixed gas containing 5% by volume of hydrogen at 350 ° C. for 3 hours under a flow of 40 cc / min, the power switch of the reactor is turned on / off every 6-12 hours at 250 ° C. and 280 ° C. Repeatedly, the conversion of CO was measured for 140 hours. The conversion rate of CO according to the reaction time is shown in Table 4 below.

Moisture contained in the reaction product is removed from the water trap, followed by an on-line gas with a carbosphere column (3.18 ㅧ 10 ^-3 m OD and 2.5 m long) and a thermal conductivity detector (TCD). Analyzed using chromatography [Hewlett Packard Co., HP6890 series].

Table 4 shows 10 wt% Cu-1 wt% Mo / Ce _0.5 Zr _0.5 O ₂ of Example 3, 12 wt% Cu-2 wt% Mo / Ce _0.5 Zr _0.5 O _{2 of} Example 8 _{, and} Comparative Example 4 10 wt% Cu / Ce _0.5 Zr _0.5 O ₂ and CO conversion rate according to the reaction time according to the temperature of the commercial catalyst of Comparative Example 11, and Examples 3 and 8 are excellent CO conversion rate compared to Comparative Examples 4 and 11 I could confirm that.

In addition, Figure 2, Example 3, Example 8 and Comparative Example 4 according to the present invention, the reaction time change (250 ~ 500 hours) at 250 ℃ as a water gas shift reaction under a commercial catalyst (Cu-ZnO / Al ₂ O ₃ ) ) Shows the CO conversion rate, and FIG. 3 shows the CO conversion rate according to the change in reaction time (0 to 500 hours) at 280 ° C. In this case, the straight lines shown in FIGS. 2 and 3 are values obtained by calculating the CO conversion rate (Y) up to 130 hours as a function of time and conversion rate, and Y = Y ₀ -aX; Y ₀ = initial CO conversion, X = Time, a = change in CO conversion over time. Here, the slope a of the straight line means the degree of deactivation of the catalyst according to the unit time, and can be interpreted as an important variable representing the durability of the catalyst.

Referring to the results of FIGS. 2 and 3, not all catalysts used in the reaction are completely durable in thermal cycling, but 10 wt% Cu-1 wt% Mo / Ce of Example 3 according to the present invention. _It was confirmed that the durability of the _0.5 Zr _0.5 O ₂ catalyst and 12 wt% Cu-2 wt% Mo / Ce _0.5 Zr _0.5 O ₂ catalyst of Example 8 was better. Cu-ZnO / Al ₂ O ₃ , a dual commercial LTS catalyst, was found to have a lower durability after 40 hours, but significantly lowered at a high temperature of 280 ° C.

The BET surface area and pore size of the catalyst before and after the thermal cycling reaction were measured by performing a physical adsorption experiment of nitrogen using a Quantachrom Adsorption Analyzer (Autosorb-1C). The BET surface area and pore size of the commercial LTS catalyst (Cu-ZnO / Al ₂ O ₃ ) after the thermal cycling reaction at 280 ° C. for 130 hours were reduced by 30% and 14%, respectively, compared to before the reaction. Cu-Mo / Ce _0.5 Zr _0.5 O ₂ catalyst of 8 reduced the BET surface area and pore size by 11% and 8%, respectively, after the reaction. From the results, it can be seen that the catalyst of the present invention has excellent durability against thermal cycling as compared to a commercial LTS catalyst. The deactivation of the Cu-ZnO / Al ₂ O ₃ catalyst during the thermal cycling reaction was believed to be due to the sintering of the active metal and could be confirmed by XRD, SEM and TEM analysis [DJ Moon, JW Ryu, Catal . Letters 92 (1-2) (2004) 17].

In summary, from the results of Examples 1 to 9 and Comparative Examples 1 to 16 of the present invention, a binary active metal supported catalyst having copper (Cu) and molybdenum (Mo) simultaneously supported on the ceria-zirconia carrier of the present invention was 280 ° C. Above, specifically, the high reaction activity for water gas conversion reaction in the reaction temperature range of 280 ~ 340 ℃ and the durability in thermal cycling (250 ° C or higher) than the conventional commercial LTS catalyst commercialized as a replacement WGS catalyst The likelihood is high.

As described above, the reaction temperature range of 280 to 340 ° C. in the case of applying to the water gas shift reaction a catalyst supported simultaneously with copper (Cu) and molybdenum (Mo) on the ceria-zirconia carrier according to the present invention. It can be seen from Figures 1 to 3 that the excellent catalytic activity as well as the durability against thermal cycling at 250 ° C or higher compared to the copper (Cu) mono-based catalyst and a conventional commercial catalyst. In addition, the catalyst according to the present invention is expected to increase the durability against sulfur even when applied to the water gas shift (WGS) reaction because of the resistance to sulfur, which is generally known by the influence of Mo added. do.

Therefore, the catalyst of the present invention can be applied to a fuel reformer for fuel cells, a domestic fuel reformer, a fuel reformer for a polymer electrolyte fuel cell (PEMFC), a hydrogen station, a petrochemical process, and especially a gasoline, liquefied petroleum gas (LPG). In addition, it is expected to be applied to various fields such as water gas shift reaction (WGS) to reduce carbon monoxide concentration after performing various hydrocarbon reforming reactions.

Figure 1 shows the CO conversion rate according to the temperature change (200 ~ 340 ℃) by performing the water gas conversion reaction in Examples 3, 5, 8 and Comparative Example 1, Comparative Example 4, Comparative Example 11 according to the present invention .

2 is a water gas conversion reaction in Examples 3, 8 and Comparative Example 4, a commercial catalyst according to the present invention, showing the CO conversion rate at 250 ℃ for 0 to 500 hours.

3 is a water gas conversion reaction in Examples 3, 8 and Comparative Example 4, a commercial catalyst according to the present invention, it shows the CO conversion for 0 to 500 hours at 280 ℃.

Claims (8)

As a catalyst for the water gas conversion reaction represented by the following formula (1), The water gas shift (WGS) reaction is a fuel reformer for fuel cell vehicle mounting, a domestic fuel reformer, a polymer reformer for a polymer electrolyte fuel cell (PEMFC), a hydrogen station or a petrochemical process, The catalyst is supported on a ceria-zirconia carrier and simultaneously contains copper (Cu) and molybdenum (Mo) as active ingredients, the copper (Cu) is contained in 10% by weight of the carrier, and the molybdenum (Mo) in the carrier 1-2 weight percent, The catalyst for water gas shift reaction has a CO conversion of 64.35% -75.00% at 320 ° C. in a medium temperature range, and 66.50% -76.42% at 340 ° C., a catalyst for water gas shift (WGS) reaction: [Formula 1] Cu-Mo / Ce _x Zr _1-x O ₂ In Formula 1, 0.3 ≦ x <0.7. delete delete delete delete In the method for producing a catalyst for water gas shift (WGS) reaction of claim 1, Preparing a slurry by mixing precursors of ceria (Ce) and zirconia (Zr) with ultrapure water, respectively; Adding urea (CH ₄ N ₂ O) to the slurry in an amount of 0.1 to 5 mol%, stirring, drying and calcining to prepare a ceria-zirconia carrier; Dissolving and mixing the ceria-zirconia carrier in distilled water to prepare a ceria-zirconia carrier slurry; Dissolving each of the copper (Cu) precursor and the molybdenum (Mo) precursor in ultrapure water to prepare an active metal salt aqueous solution; 5 steps of preparing a catalyst precursor by impregnating the aqueous solution of the active metal salt in the ceria-zirconia carrier slurry; And Method for producing a catalyst for water gas shift (WGS) reaction comprising the six steps of drying and sintering the impregnated catalyst precursor. A process for producing a synthesis gas, characterized in that to produce a synthesis gas by performing a water gas shift (WGS) reaction under the conditions of the catalyst of claim ¹ at a reaction temperature of 200 to 450 ° C. and a space velocity of 1,000 to 50,000 h ⁻¹ . delete

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