Catalyst for dehydrogenation reaction of formate and hydrogenation reaction of bicarbonate and preparation method thereof

Abstract

Provided is a method for preparing a catalyst for a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, the method including: adding a silica colloid to a polymerization step of polymerizing aniline and reacting the resulting mixture to form a poly(silica-aniline) composite; carbonizing the corresponding poly(silica-aniline) composite under an atmosphere of an inert gas; removing silica particles from the corresponding poly(silica-aniline) composite to form a polyaniline-based porous carbon support; and fixing palladium particles on the corresponding polyaniline-based porous carbon support to prepare the catalyst.

Claims

1. A catalyst for a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, the catalyst comprising: a polyaniline-based porous carbon support, in which palladium particles are fixed, wherein the catalyst further comprises a region in which nitrogen is included, and wherein the catalyst has a specific surface area of 500 to 1,200 (m.sup.2.Math.g.sup.1).

2. The catalyst according to 9, wherein the polyaniline-based porous carbon support is a reaction product of a reaction of removing silica particles from a carbon composite produced via carbonization of a poly(silica-aniline) composite, and wherein the poly(silica-aniline) composite is a reaction product produced by mixing and reacting a silica colloid in a polymerization step of polyaniline.

3. The catalyst according to 9, wherein the catalyst has a spherical structure, and the region in which nitrogen is included has a pyridinized or pyrrolinized structure.

4. A method for releasing and storing hydrogen via a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate using the catalyst according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view showing a method for preparing a catalyst according to an embodiment of the present disclosure.

(2) FIGS. 2A and 2B show a schematic view of a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, in which the catalyst prepared according to an embodiment of the present disclosure is used, and the reaction mechanisms thereof, respectively.

(3) FIGS. 3A and 3B are photographs showing the structural change of a catalyst particle according to Comparative Example 1.

(4) FIGS. 4A and 4B are photographs showing the structural change of a catalyst particle according to Example 1.

(5) FIGS. 5A and 5B are photographs showing the structural change of a catalyst particle according to Example 2.

(6) FIGS. 6A and 6B are photographs showing the structural change of a catalyst particle according to Example 3.

(7) FIGS. 7A and 7B are photographs showing the structural change of a catalyst particle according to Example 7.

(8) FIGS. 8A and 8B are photographs showing the structural change of a catalyst particle according to Example 6.

(9) FIGS. 9A and 9B are photographs showing the structural change of a catalyst particle according to Example 5.

(10) FIGS. 10A and 10B are photographs showing the structural change of a catalyst particle according to Example 4.

(11) FIGS. 11A and 11B are graphs showing the change in activity of the catalyst according to the change in amount of silica, and FIGS. 11C and 11D are graphs showing the change in activity of the catalyst according to the change in temperature in the carbonization step.

(12) FIG. 12A is a graph showing the Raman analysis results of the catalysts prepared according to Examples, FIG. 12B is a graph showing an atomic ratio of nitrogen/carbon obtained from an XPS analysis result, FIG. 12C is a graph showing a distribution form of a functional group including nitrogen obtained from the XPS analysis result, and FIG. 12D is a schematic view showing a potential structure of an expected carbon support including a nitrogen atom.

DETAILED DESCRIPTION

(13) In the present specification, the term poly(silica-aniline) composite means a product produced by mixing a silica colloid together, and then reacting the resulting mixture in a polymerization step of polymerizing aniline to form polyaniline. On the far left side of FIG. 1, a schematic structure of the poly(silica-aniline) composite is shown (shown as polyaniline (PANI)-SiO.sub.2).

(14) Hereinafter, embodiments of the present disclosure will be described in detail with reference to accompanying drawings. Embodiments of the present disclosure have been described with reference to accompanying drawings, but have been described for illustration, and the technical spirit of the present disclosure and the configuration and application thereof are not limited thereby.

(15) Method for Preparing Catalyst for Dehydrogenation Reaction of Formate and Hydrogenation Reaction of Bicarbonate

(16) In an embodiment of the present disclosure, provided is a method for preparing a catalyst for a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, the method including: adding a silica colloid to a polymerization step of polymerizing aniline to form polyaniline and reacting the resulting mixture to form a poly(silica-aniline) composite; carbonizing the poly(silica-aniline) composite under an atmosphere of an inert gas; removing silica particles from the poly(silica-aniline) composite to form a polyaniline-based porous carbon support; and fixing the palladium particles on the polyaniline-based porous carbon support to prepare the catalyst.

(17) FIG. 1 is a schematic view showing a method for preparing a catalyst according to an embodiment of the present disclosure. Hereinafter, the preparation method will be examined in detail with reference to FIG. 1.

(18) First, a silica colloid is added to a polymerization step of polymerizing aniline to form polyaniline, and the resulting mixture is reacted to form a poly(silica-aniline) composite.

(19) Specifically, in the polymerization step of aniline which is a precursor for polyaniline, aniline is slowly added to a solution including a silica colloid and the resulting mixture is subjected to polymerization reaction to prepare a poly(silica-aniline) composite.

(20) In an exemplary embodiment, the silica colloid may be one or more selected from the group consisting of silica sol, silica gel, silica nanoparticles, and the like.

(21) In an exemplary embodiment, in the addition step, the silica colloid may be added in an amount of 4 g to 18 g, and preferably 13 g to 17 g, per 0.02 mol of aniline. When the silica particles are mixed in an amount of less than 4 g, a catalyst to be prepared later may be prepared so as to have a small specific surface area, and when the silica particles are mixed in an amount of more than 18 g, a porous catalyst structure may not be properly formed due to the aggregation phenomenon of silica.

(22) In an exemplary embodiment, the specific surface area of the catalyst may be increased in proportion to an amount of silica colloid added within a range not degrading the activity of a catalyst finally produced by the silica colloid.

(23) The mixing reaction may be performed for about 18 to 24 hours, and accordingly, a poly(silica-aniline) composite produced by polymerizing a mixture of aniline with silica may be prepared.

(24) Subsequently, the poly(silica-aniline) composite is carbonized under an atmosphere of an inert gas.

(25) Specifically, under an atmosphere of an inert gas such as nitrogen (N.sub.2) or argon (Ar), the poly(silica-aniline) composite may be subjected to heat treatment to carbonize silica of the poly(silica-aniline) composite.

(26) In an exemplary embodiment, the carbonization process may be performed according to a single process performed at a temperature of 500 to 1,000 C. for 3 to 8 hours, and specifically, may be performed within a temperature range of 790 to 810 C.

(27) In contrast, in an exemplary embodiment, the carbonization process may be performed dividedly in two steps of a first carbonization process and a second carbonization process.

(28) In an Example, the first carbonization process is a carbonization process performed at a relatively low temperature of about 200 to 400 C. for 2 to 4 hours, and may be a step of preventing a poly(silica-aniline) composite from being structurally damaged.

(29) In an exemplary embodiment, the second carbonization process is performed at a relatively high temperature for 1 to 4 hours as a full-fledged carbonization process, and at this time, a poly(silica-aniline) composite may be carbonized to form a silica-nitrogen-carbon nano composite.

(30) In an Example, the second carbonization process may be performed within a temperature range of 500 to 1,000 C., preferably 700 to 900 C., and more preferably 790 to 810 C. When the second carbonization process is performed at a temperature of less than 500 C., the composite is not sufficiently carbonized, so that an aromatic ring by a formed intermolecular cross-linkage or double bond of the carbon structure is not properly formed, and as a result, a desired graphitic carbon structure cannot be obtained, and when the second carbonization process is performed at a temperature of more than 1,000 C., a structural defect of a poly(silica-aniline) composite to be carbonized may be caused.

(31) Meanwhile, when the second carbonization process is performed at a temperature of about 800 C., the activity of a catalyst to be finally formed may be more improved, and as the carbonization process is performed, the improved activity is because the structure including nitrogen in the poly(silica-aniline) composite is pyrrolinized or pyridinized

(32) Subsequently, silica particles are removed from the carbonized poly(silica-aniline) composite to form a polyaniline-based porous carbon support.

(33) Specifically, the poly(silica-aniline) composite is impregnated in a solution such as sodium hydroxide and silica particles are removed from the carbonized poly(silica-aniline) composite to form a polyaniline-based porous carbon support. As the silica particles are removed from the poly(silica-aniline) composite, pores may be formed at sites in which the silica particles used to be present.

(34) Thereafter, the polyaniline-based porous carbon support may be filtered and dried to prepare a polyaniline-based porous carbon support in the form of powder.

(35) Finally, palladium particles are fixed on the polyaniline-based porous carbon support to prepare a catalyst including a porous carbon support in which palladium particles are impregnated.

(36) Specifically, after the polyaniline-based porous carbon support is dispersed in an aqueous solution, a palladium precursor is added in an amount of 1 to 5 wt % (preferably 1 to 3 wt %) based on the total weight of the support thereto, and then the resulting mixture is stirred at normal temperature for 2 to 6 hours, and then dried. Accordingly, palladium particles or palladium ions may be impregnated in pores of the polyaniline-based porous carbon support.

(37) In an exemplary embodiment, the palladium precursor may include one or more selected from the group consisting of aqueous Pd.sup.2+-based compounds, such as Pd(NO.sub.3).2H.sub.2O, PdCl.sub.2, Pd(OAc).sub.2, and PdI.sub.2.

(38) Meanwhile, if palladium ions are impregnated in the support, a catalyst may be finally prepared by reducing Pd.sup.2+ ions impregnated in the support to Pd through an additional reduction process.

(39) In an exemplary embodiment, the catalyst may be represented by the following Chemical Formula 1.
Pd/PDMC-T-X[Chemical Formula 1]

(40) In Chemical Formula 1, Pd and PDMC mean palladium and a polyaniline-based porous carbon support, respectively, T means a temperature in the carbonization step, and X is a weight (g) of the silica colloid added per 0.02 mmol of aniline in the polymerization step of polyaniline.

(41) In Chemical Formula 1, T may have a value within a range of 500 to 1,000 C., and a value within a temperature range of preferably 700 to 900 C., and more preferably 790 to 810 C.

(42) Further, in Chemical Formula 1, X may have a value within a range of 4 g to 18 g, and preferably 13 g to 17 g.

(43) In an exemplary embodiment, the palladium particles may have a diameter of about 1.0 to 2.0 nm, preferably 1.5 to 1.7 nm. When the particle particles have a relatively small diameter as described above, the particles may be widely dispersed and impregnated in the support, and as catalyst active sites capable of being reacted are increased, the activity of the catalyst may be increased as compared to an equal amount of palladium.

(44) In an exemplary embodiment, the specific surface area of the catalyst may be varied by conditions such as a temperature condition of the carbonization process of the poly(silica-aniline) composite and the content of silica colloid to be added in the polymerization step of aniline.

(45) For example, as the content of silica colloid is increased, the specific surface area of the catalyst may be increased.

(46) Accordingly, the aforementioned conditions and the like may be optimized to prepare a catalyst for a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, which has a high specific surface area.

(47) In an exemplary embodiment, the catalyst may have a specific surface area of about 500 to 1,200 (m.sup.2.Math.g.sup.1), preferably 800 to 1,200 (m.sup.2.Math.g.sup.1), and more preferably 900 to 1,100 (m.sup.2.Math.g.sup.1). The reason that the catalyst has a wide specific surface area as described above is because pores are formed in the support by leaching of the silica colloid, and the specific surface area may be adjusted according to the amount of silica colloid initially introduced. The important reason that the catalyst has a wide specific surface area is because palladium nanoparticles having a much smaller size may be uniformly dispersed on the entire support by a wide specific surface area of the support, and it is possible to expect high catalytic activity because much more catalyst active sites are formed accordingly.

(48) As described above, the catalyst prepared by the method is prepared so as to have a high specific surface area and a structure which easily provides electrons to palladium, may be usefully utilized for a dehydrogenation reaction of formate and a hydrogenation of bicarbonate, and may also be excellently used in a secondary battery including the same.

(49) Catalyst for Dehydrogenation Reaction of Formate and Hydrogenation Reaction of Bicarbonate

(50) In another exemplary embodiment of the present disclosure, provided is a catalyst for a dehydrogenation reaction of formate and a hydrogenation reaction of bicarbonate, which includes a polyaniline-based porous carbon support, in which palladium particles are fixed, and has a specific surface are of 500 to 1,200 (m.sup.2.Math.g.sup.1), as a catalyst for a dehydrogenation reaction of formate and hydrogenation reaction of bicarbonate. Since the catalyst is a catalyst prepared by the above-described method for preparing a catalyst, the description on a configuration which is substantially the same as or similar to the method for preparing a catalyst will be omitted.

(51) In an exemplary embodiment, the polyaniline-based porous carbon support may be a reaction product of a reaction of removing silica particles from a carbon composite produced via carbonization of a poly(silica-aniline) composite (i.e., a reaction product via carbonization of a poly(silica-aniline) composite), and the poly(silica-aniline) composite may be a reaction product produced by mixing and reacting a silica colloid in the polymerization step of polyaniline.

(52) In an exemplary embodiment, the catalyst has a spherical structure, and may be represented by the following Chemical Formula 1.
Pd/PDMC-T-X[Chemical Formula 1]

(53) In Chemical Formula 1, Pd and PDMC mean palladium and a polyaniline-based porous carbon support, respectively, T means a temperature in the carbonization step and a temperature within a range of 500 to 1,000 C., and X is a weight (g) of the silica colloid added per 0.02 mol of aniline in the polymerization step of polyaniline, and may be an integer within a range of 4 to 18 (g).

(54) The catalyst according to the present disclosure has two or more advantages.

(55) First, since the support of the catalyst include pores formed on the surface thereof by using a silica colloid, the surface area of the support may be maximized. Accordingly, when metal particles such as palladium are later impregnated, the catalyst active sites of palladium to be impregnated may be maximized, and the activity of the catalyst may be improved accordingly.

(56) Further, a region in which nitrogen is included in the catalyst has a pyridinized or pyrrolinized structure, and since the structure is advantageous for providing electrons, nitrogen in the pyridinized or pyrrolinized structure easily provides electrons to palladium particles. Accordingly, since the catalytic activity may be more imparted to palladium particles, the activity of the catalyst including the same may be finally improved.

(57) Accordingly, when the dehydrogenation reaction of formate and the hydrogenation of bicarbonate are performed by using the catalyst, the yield may be improved.

(58) Hereinafter, the present disclosure will be described in more detail through Examples. These Examples are only for exemplifying the present disclosure, and it will be obvious to those skilled in the art that the scope of the present disclosure is not interpreted to be limited by these Examples.

EXAMPLES

Example 1

(59) (1) After 0.2 mol of APS (NH.sub.4).sub.2S.sub.2O.sub.8 was added to 100 mL of an aqueous solution in which a 1.0 M formic acid was dissolved at 2 C., the resulting mixture was stirred until being completely dissolved, and then 4 g of Ludox HS-40 silica colloid (40 wt % in H.sub.2O) was slowly added thereto under stirring, and then 20 mmol of aniline was slowly added thereto. Thereafter, the resulting mixture was stirred at 2 to 5 C. for 24 hours.

(60) (2) Thereafter, centrifugation was performed at 15,000 rpm for about 20 minutes, then the supernatant was discarded, distilled water was again added thereto, and then after centrifugation was performed at 15,000 rpm for 30 minutes, the process was repeated three times. Subsequently, ethanol was added to the solution, and then centrifugation was performed at 15,000 rpm for 20 minutes, and the process was repeated two times. Thereafter, the resulting product was dried, and then a poly(silica-aniline) composite in a form of powder was obtained.

(61) (3) Subsequently, the poly(silica-aniline) composite was subjected to heat treatment under an atmosphere of an inert gas (Ar or N.sub.2), and specifically, after the temperature was increased at a speed of 1 C./min, reached to 300 C., and then maintained for 3 hours, the temperature was reached to 1,000 C. at a speed of 10 C./min, and then maintained for 2 hours.

(62) (4) Subsequently, the carbonized poly(silica-aniline) composite was impregnated in a 1 M aqueous NaOH solution, and then maintained at 100 C. for 24 hours to remove the silica colloid. Thereafter, a polyaniline-based porous carbon support in a form of powder was prepared through filtering and drying processes.

(63) (5) Thereafter, the polyaniline-based porous carbon support was dispersed in the aqueous solution, then a palladium precursor (Pd(NO.sub.3).2H.sub.2O) was added in a desired amount (1 to 3 wt % of Pd compared to the support) thereto, and then the resulting mixture was stirred at normal temperature for 3 hours, and then filtered and dried. Thereafter, a catalyst in a form of powder was obtained by reducing Pd.sup.2+ to Pd(0) at 250 C. while flowing a hydrogen gas.

Example 2

(64) The catalyst was prepared by performing the same process as in Example 1, except that 8 g of a silica colloid was added instead of 4 g of Ludox HS-40 silica colloid.

Example 3

(65) The catalyst was prepared by performing the same process as in Example 1, except that 16 g of a silica colloid was added instead of 4 g of Ludox HS-40 silica colloid.

Example 4

(66) The catalyst was prepared by performing the same process as in Example 3, except that the temperature in the heat treatment step (3) was reached to 900 C.

Example 5

(67) The catalyst was prepared by performing the same process as in Example 3, except that the temperature in the heat treatment step (3) was reached to 800 C.

Example 6

(68) The catalyst was prepared by performing the same process as in Example 3, except that the temperature in the heat treatment step (3) was reached to 700 C.

Example 7

(69) The catalyst was prepared by performing the same process as in Example 3, except that the temperature in the heat treatment step (3) was reached to 500 C.

Example 8

(70) The catalyst was prepared by performing the same process as in Example 5, except that 94 mol/g of palladium was impregnated in the support.

Comparative Example 1

(71) The catalyst was prepared by performing the same process as in Example 1, except that the Ludox HS-40 silica colloid was not added at all.

Comparative Example 2

(72) As a comparative example, a Pd/C catalyst (Sigma-Aldrich, 10 wt. %) was used.

Experimental Example 1

(73) The surface characteristics of the catalysts prepared in Comparative Example 1 and Examples 1 to 3 were measured, and are shown in Table 1. Further, each surface area of the catalysts was measured by an electron microscope, and is shown in FIGS. 3A to 6B.

(74) TABLE-US-00001 TABLE 1 Content (g) Metal Average of silica A.sub.BET D.sub.BJH V loading/10.sup.1 size of Pd Sample colloid (m.sup.2 .Math. g.sup.1) (nm) (cm.sup.3 .Math. g.sup.1) mmol/g.sub.cat (nm) Comparative Pd/PDM 0 g 260 2.5 0.2 0.7 16.2 Example 1 C-1000-0 Example 1 Pd/PDM 4 g 817 7.4 1.5 2.3 1.5 C-1000-4 Example 2 Pd/PDM 8 g 919 8.0 1.8 2.0 1.5 C-1000-8 Example 3 Pd/PDM 16 g 994 9.7 2.4 1.8 1.7 C-1000-16

(75) When Table 1 and FIGS. 3A to 6B were examined, it could be confirmed that as the amount of silica colloid was increased under the same conditions, the specific surface area of the catalyst was improved. Further, it could be confirmed that as the surface area of the support was increased, Pd nanoparticles were uniformly dispersed in small sizes and impregnated.

(76) In contrast, it could be confirmed that when the silica colloid was not mixed (Comparative Example 1) in the synthesis step, Pd nanoparticles having a large size were impregnated in a small amount, but when the silica colloid was mixed, Pd nanoparticles having a small size were impregnated in a large amount.

Experimental Example 2

(77) The surface characteristics of the catalysts prepared in Examples 4 to 7 were measured, and are shown in Table 2. In addition, each surface area of the catalysts was measured by an electron microscope, and is shown in FIGS. 7A to 10B.

(78) TABLE-US-00002 TABLE 2 Heat treatment Metal Average Temperature A.sub.BET D.sub.BJH V loading/10.sup.1 size of Pd Sample ( C.) (m.sup.2 .Math. g.sup.1) (nm) (cm.sup.3 .Math. g.sup.1) mmol/g.sub.cat (nm) Example 4 Pd/PDM 900 934 9.2 2.2 1.3 1.6 C-900-16 Example 5 Pd/PDM 800 1080 9.4 2.5 1.5 1.6 C-800-16 Example 6 Pd/PDM 700 845 8.4 1.8 1.4 1.5 C-700-16 Example 7 Pd/PDM 500 510 3.4 0.4 1.5 1.7 C-500-16

(79) When FIGS. 7A to 10B were examined, it could be confirmed that as the heat treatment temperature was increased, the specific surface area of the catalyst was usually increased, but particularly, when the heat treatment temperature was 800 C., the specific surface are of the catalyst was most greatly increased.

Experimental Example 3

(80) The dehydrogenation reaction of formate was performed by using the catalysts according to Examples 1 to 8 and Comparative Examples 1 and 2. Specifically, 5 mL of 1 M sodium formate and 25 mg of each of the catalysts prepared according to Examples 1 to 8 and Comparative Example 1 were reacted at 80 C. Further, in the case of the catalyst according to Comparative Example 2, 5.0 mg of the catalyst was reacted. Thereafter, the turnover frequency in each case was measured, and is shown in Table 3 and FIGS. 11A to 11D.

(81) TABLE-US-00003 TABLE 3 Pd/PDMC-T-X T (Heat treatment X (Content of temperature) silica colloid) Turnover frequency (h.sup.1) Comparative 1000 0 No reaction Example 1 Example 1 1000 4 813 Example 2 1000 8 1054 Example 3 1000 16 1396 Example 4 900 16 1570 Example 5 800 16 1854 Example 6 700 16 1515 Example 7 500 16 1281 Example 8 800 16 2562 Comparative Pd/C 1034 Example 2

(82) When Table 3 and FIGS. 11A to 11D were examined, it could be confirmed that the larger the amount of silica colloid was, the higher the surface area of the catalyst became, and accordingly, high catalytic activity values were exhibited. Meanwhile, it could be confirmed that when the heat treatment was performed at 800 C. (Examples 5 and 8) in the case of carbonization (heat treatment) temperature, the highest activity was exhibited, and it could be confirmed that particularly, these catalysts exhibited better catalytic activity than Pd/C catalysts most of which are commercially available.

Experimental Example 4

(83) The hydrogenation reaction of bicarbonate was performed by using the catalysts according to Examples 3 to 8 and Comparative Example 2. Specifically, 10 mL of 1 M HCO.sub.3Na and 50 mg of the catalyst were reacted under conditions of 80 C. and 40 bar for 24 hours. Thereafter, the conversion rate and turnover number thereof were measured and are shown in Table 4.

(84) TABLE-US-00004 TABLE 4 Pd/PDMC-T-X T (Heat Turnover treatment X (Content of Conversion number temperature) silica colloid) rate (%) (TON) Example 3 1000 16 70 770 Example 4 900 16 73 985 Example 5 800 16 82 1144 Example 6 700 16 74 1018 Example 7 500 16 22 311 Example 8 800 16 65 1646 Comparative Pd/C 52 333 Example 2

(85) When Table 4 was examined, it could be confirmed that when the heat treatment was performed at 800 C. in the carbonization process, the catalyst exhibited the highest activity in the hydrogenation reaction of bicarbonate, and it could be confirmed that particularly, the catalyst prepared in the present Example exhibited better catalytic activity than Pd/C catalysts all of which are commercially available.

Experimental Example 5

(86) The catalysts prepared in Examples 3 to 7 were analyzed by using XPS (FIG. 12A), and the atomic ratios of nitrogen/hydrogen thereof were measured (FIG. 12B). Among them, the distribution forms of the catalysts according to Examples 3 to 7 were observed, and are shown in FIG. 12C.

(87) As the carbonization temperature was increased, the amount of carbon carbonized was increased, and when the ratio of N/C in FIG. 12B was examined, it could be confirmed that when the carbonization temperature was 500 C., nitrogen was present in the largest amount, and as the temperature was increased, the ratio of N/C was lowered. That is, it could be confirmed that even though the ratio of nitrogen (N) was decreased and the carbonization temperature was decreased, the catalytic activity of the catalyst was excellent.

(88) Meanwhile, in the case of Example 5 in which the carbonization process was performed at 800 C. at which the catalytic activity is the best as in FIG. 12C, the pyrrolinized or pyridinized structure was exhibited most abundantly, and as a result, it could be known that the two structures positively affect the catalytic activity.

(89) That is, when the support is doped with a heteroatom such as nitrogen, it is natural that catalytic activity is increased because nitrogen transports electrons to Pd to increase the electron density, but it could be confirmed that not only the amount of nitrogen, but also the electron density of Pd have been further increased because the case where the support is doped with a heteroatom becomes a state where electrons are transported to Pd more easily than the case where nitrogen is present in a structure of pyrroline or pyridine as in Example 5. That is, it could be confirmed that the amount of nitrogen was not only important, but it also affects the catalyst whether nitrogen is present in what form in the support.

Experimental Example 6

(90) When the hydrogenation reaction of bicarbonate was performed by using the catalyst prepared in Example 3, gases to be discharged were detected, and components thereof were detected and are shown in Table 5.

(91) TABLE-US-00005 TABLE 5 H.sub.2 O.sub.2 N.sub.2 CH.sub.4 CO CO.sub.2 Content (%) 38.7 7.4 48.1 0 0 0

(92) When Table 5 was examined, it could be confirmed that when the hydrogenation reaction was performed by using the catalyst prepared according to the present disclosure, carbon monoxide (CO) was not generated. Accordingly, it could be confirmed that a gas harmful to the catalyst was not generated, and thus, the activity of the catalyst could be sustained.

(93) The Examples of the present disclosure previously described should not be interpreted to limit the technical spirit of the present disclosure. The scope of the present disclosure to be protected is limited only by the matters described in the claims, and those skilled in the art of the present disclosure can improve and change the technical spirit of the present disclosure in various forms. Therefore, such improvements and changes would fall within the scope of the present disclosure to be protected as long as they are obvious to those skilled in the art.