1. Patent Search
  2. Details

PREPARATION METHOD OF PLATINUM/TIN/METAL/ALUMINA CATALYST FOR DIRECT DEHYDROGENATION OF N-BUTANE AND METHOD FOR PRODUCING C4 OLEFINS USING SAID CATALYST

20180133694 ยท 2018-05-17

    Inventors

    Cpc classification

    International classification

    Abstract

    The provided is a method for preparing a platinum-tin-metal-alumina catalyst by comprising: as an active ingredient, platinum which has a high activity in a direct dehydrogenation reaction of n-butane, tin which can increase the catalyst stability by preventing carbon deposition; additionally metal for reducing the level of catalyst inactivation over the reaction time; and an alumina carrier for supporting said components. Further, provided is a method for producing a high value product, C4 olefins from low cost n-butane by using the catalyst prepared by the method according to the present invention in a direct dehydrogenation reaction.

    Claims

    1. A method for producing C4 olefins, comprising the following steps: (a) preparing a solution of a zinc precursor compound by dissolving a zinc precursor into a first solvent; (b) impregnating the zinc precursor solution to an alumina carrier; (c) thermally drying and heat-treating the product obtained from the above step (b) so as to obtain a zinc-alumina wherein zinc is supported to an alumina carrier; (d) preparing a tin precursor solution by dissolving a tin precursor and an acid into a second solvent to form a tin precursor solution; (e) impregnating the above-prepared tin precursor solution from the step (d) to the zinc-alumina prepared by the above step (c); (f) thermally drying and heat-treating the product obtained from the above step (e) to obtain a tin-zinc-alumina; (g) preparing a platinum precursor solution by dissolving a platinum precursor into a third solvent; (h) impregnating the above-prepared platinum precursor solution from the step (g) to the tin-zinc-alumina prepared from the above step (f); (i) thermally drying and heat-treating the product obtained from the above step (h) so as to obtain a platinum-tin-zinc-alumina catalyst; and (j) conducting a direct dehydrogenation reaction of n-butane by using a mixed gas comprising n-butane and nitrogen as reactants on the platinum-tin-zinc-alumina catalyst.

    2. The method according to claim 1, wherein the zinc precursor used in the above step (a) is at least one selected from zinc chloride, nitrate, bromide, oxide, hydroxide or acetate precursor.

    3. The method according to claim 1, wherein the zinc content of the step (a) is 0.2-5 wt %, based on the total weight of the finally obtained platinum-tin-zinc-alumina catalyst.

    4. The method according to claim 1, wherein each first, second and third solvent used in the above step (a), (d) and (g), respectively is water or an alcohol.

    5. The method according to claim 1, wherein, in the step (c), the thermal drying is carried out at a temperature range of 50-200 C., and the heat treatment is carried out at a temperature range of 350-1000 C.

    6. The method according to claim 1, wherein, in the step (f) and (i), the thermal drying is carried out at a temperature range of 50-200 C., and the heat treatment is carried out at a temperature range of 400-800 C.

    7. The method according to claim 1, wherein, in the step (j), the direct dehydrogenation reaction of n-butane is carried out at a temperature range of 300-800 C.

    8. The method according to claim 1, wherein, in the step (j), n-butane:nitrogen ratio by volume in the mixed gas is 1:0.2-10.

    9. The method according to claim 1, wherein, in the step (j), the feeding amount of the mixed gas is a space velocity of 10-6000 cc.Math.hr.sup.1.Math.gcat.sup.1 based on n-butane.

    Description

    BRIEF DESCRIPTION OF THE DRAWINGS

    [0069] FIG. 1 is a graph showing the differences in the direct dehydrogenation reaction yield between catalysts during the direct dehydrogenation reaction of n-butane on a platinum-tin-alumina catalyst and 5 species of platinum-tin-transition metal-alumina catalysts according to Examples of the present invention for 360 minutes.

    [0070] FIG. 2 is a graph showing the differences in the direct dehydrogenation reaction yield between catalysts after the direct dehydrogenation reaction of n-butane on a platinum-tin-alumina catalyst and 5 species of platinum-tin-transition metal-alumina catalysts according to Examples of the present invention for 360 minutes.

    [0071] FIG. 3 is a graph showing the differences in the direct dehydrogenation reaction yield between catalysts during the direct dehydrogenation reaction of n-butane on 4 species of platinum-tin-alkali metal-alumina catalysts according to Examples of the present invention for 360 minutes.

    [0072] FIG. 4 is a graph showing the differences in the direct dehydrogenation reaction yield between catalysts during the direct dehydrogenation reaction of n-butane on 3 species of platinum-tin-alkali earth metal-alumina catalysts according to Comparative examples for 360 minutes.

    EXAMPLES OF THE INVENTION

    [0073] Hereinafter, the present invention is further

    [0074] described in detail through specific embodiments. However, these examples are provided only with an illustrative purpose without any intention to limit the present invention.

    Preparation Example 1

    [0075] Preparation of Zinc-Alumina (ZnAl.sub.2O.sub.3) Through an Impregnation of Zinc by Using a Conventional Alumina Carrier

    [0076] For preparing ZnAl.sub.2O.sub.3 in which zinc was supported to the content of 0.5 wt % on a conventional alumina carrier (-Alumina, surface area=180 m.sup.2g), 0.046 g of zinc nitrate hexahydrate was placed in a beaker and dissolved in distilled water therein. To thus prepared solution, when the precursor was completely dissolved, 2.0 g of conventional alumina was placed thereto, and the resulted mixture was heated at 70 C. with stirring until distilled water was completely evaporated, resulting in a solid product. After that, the solid product was additionally dried in an oven at a temperature of 80 C. for about 12 hours, and thus obtained sample was heat-treated in an electric furnace maintained at a temperature of 600 C. in an air atmosphere for 4 hours so as to form a zinc-alumina product, wherein 0.5% of zinc was supported to alumina. The resulted product was referred as ZnAl.sub.2O.sub.3.

    Preparation Example 2

    [0077] Preparation of Transition Metal-Alumina (M-Al.sub.2O.sub.3) Through an Impregnation of Various Transition Metal (Ga, In, La, Ce) by Using a Conventional Alumina Carrier

    [0078] According to the above method described in the preparation example 1, various transition metals were used to prepare 4 species of transition metal-alumina. Specifically, as for the various transition metal, gallium, indium, lanthanum, cerium were used, and as for the precursors, gallium(III) nitrate hydrate, indium(III) nitrate hydrate, lanthanum (III) nitrate hexahydrate and cerium(III) nitrate hexahydrate were used, respectively.

    [0079] After adjusting the metal content to become 0.5 wt %, it was impregnated so as to form a solid material, which was dried at 80 C. for about 12 hours, and heat-treated in an electric furnace maintained at a temperature of 600 C. in an air atmosphere for 4 hours, thereby preparing 4 species of transition metal-alumina catalysts in which each transition metal was supported to the amount of 0.5 wt %. The resulted products were referred as GaAl.sub.2O.sub.3, InAl.sub.2O.sub.3, LaAl.sub.2O.sub.3, CeAl.sub.2O.sub.3, respectively.

    Preparation Example 3

    [0080] Preparation of a Platinum-Tin-Alumina (PtSnAl.sub.2O.sub.3) Catalyst and a Platinum-Tin-Metal-Alumina (PtSn-M-Al.sub.2O.sub.3) Catalyst Through a Sequential Impregnation of Various Metals, and Tin and Platinum by Using a Conventional Alumina Carrier

    [0081] A platinum-tin-metal-alumina(PtSn-M-Al.sub.2O.sub.3) catalyst was prepared by the sequential impregnation of tin and platinum to the metal-alumina prepared by the above preparation examples 1 and 2, For comparison, a platinum-tin-alumina catalyst was prepared by sequential impregnation of tin and platinum to alumina.

    [0082] The preparation of the platinum-tin-metal-alumina catalyst and the platinum-tin-alumina catalyst through impregnation of each tin and platinum to metal-alumina and alumina, respectively were as follows.

    [0083] For preparing each of a tin-metal-alumina catalyst and a tin-alumina catalyst, in which tin is supported to the content of 1 wt %, by using a metal-alumina and alumina, tin (II) chloride dihydrate 0.038 g was placed in a beaker and dissolved into a small amount of hydrochloric acid 0.37 ml and distilled water 15 ml. When the precursor solution was completely dissolved, 2.0 g of each metal-alumina and alumina previously prepared according to the above preparation examples 1 and 2 was placed thereto, and the resulted mixture was heated at 70 C. with stirring until distilled water was completely evaporated. After that, the remained solid product was additionally dried in an oven at a temperature of 80 C. for about 12 hours, and thus obtained sample was heat-treated in an electric furnace maintained at a temperature of 600 C. in an air atmosphere for 4 hours so as to form each of a tin-metal-alumina (Sn-M-Al.sub.2O.sub.3) and tin-alumina (SnAl.sub.2O.sub.3) in which 1 wt % of tin was supported.

    [0084] To thus obtained tin-metal-alumina and tin-alumina product 2.0 g, chloroplatinic acid hexahydrate 0.053 g was placed in a beaker and dissolved into 10 ml distilled water so that the platinum content became 1 wt %. When the platinum precursor solution was completely dissolved, 2.0 g of each previously prepared tin-metal-alumina and tin-alumina was placed thereto, and the resulted mixture was heated at 70 C. with stirring until distilled water was completely evaporated. After that, if any, solid product remained was additionally dried in an oven at a temperature of 80 C. for about 12 hours, and thus obtained sample was heat-treated in an electric furnace maintained at a temperature of 550 C. in an air atmosphere for 4 hours so as to form a platinum-tin-metal-alumina catalyst and a platinum-tin-alumina catalyst, wherein the finally prepared catalysts were referred as PtSnZnAl.sub.2O.sub.3, PtSnGaAl.sub.2O.sub.3, PtSnInAl.sub.2O.sub.3, PtSnLaAl.sub.2O.sub.3, PtSnCeAl.sub.2O.sub.3, respectively, according to the species of metal used therein, and the catalyst having no added metal was referred as PtSnAl.sub.2O.sub.3.

    Preparation Example 4

    [0085] Preparation of a Platinum-Tin-Alkali Metal-Alumina (PtSn-M-Al.sub.2O.sub.3) Catalyst Through a Sequential Impregnation of Various Alkali Metals, and Tin and Platinum by Using a Conventional Alumina Carrier

    [0086] According to the above method described in the preparation examples 1 and 2, various alkali metals, and tin and platinum were sequentially impregnated to prepare 4 species of platinum-tin-alkali metal-alumina. Specifically, each alkali metal was impregnated to alumina to form an alkali metal-alumina product, wherein as for the alkali metal, lithium, sodium, potassium and rubidium were used, and as for the precursors, lithium nitrate, sodium nitrate, potassium nitrate and rubidium nitrate were used, respectively. To the prepared alkali metal-alumina, tin and platinum were sequentially impregnated according to the preparation example 3 so as to form a platinum-tin-alkali metal-alumina catalyst, and each catalyst was referred as PtSnLiAl.sub.2O.sub.3, PtSnNaAl.sub.2O.sub.3, PtSnKAl.sub.2O.sub.3, PtSnRbAl.sub.2O.sub.3, according to the species of metal used therein.

    Preparation Example 5 (Comparative Preparation Example)

    [0087] Preparation of a Platinum-Tin-Alkali Earth Metal-Alumina (PtSn-M-Al.sub.2O.sub.3) Catalyst Through a Sequential Impregnation of Various Alkali Earth Metals, and Tin and Platinum by Using a Conventional Alumina Carrier

    [0088] According to the above method described in the preparation examples 1 and 2, various alkali earth metals, and tin and platinum were sequentially impregnated to prepare 3 species of platinum-tin-alkali earth metal-alumina. Specifically, each alkali earth metal was impregnated to alumina to form an alkali earth metal-alumina product, wherein as for the alkali earth metal, magnesium, calcium and barium were used, and as for the precursor, magnesium nitrate hexahydrate, calcium nitrate tetrahydrate and barium nitrate were used, respectively. To the prepared alkali earth metal-alumina, and tin and platinum were sequentially impregnated according to the preparation example 3 so as to form a platinum-tin-alkali earth metal-alumina catalyst, and each catalyst was referred as PtSnMgAl.sub.2O.sub.3, PtSnCaAl.sub.2O.sub.3, PtSnBaAl.sub.2O.sub.3, according to the species of metal used therein.

    Example 1

    [0089] Direct Dehydrogenation Reaction in a Continuous Flow Catalyst Reactor

    [0090] A direct dehydrogenation reaction was conducted by using the platinum-tin-zinc-alumina catalyst prepared from the above preparation example 3.

    [0091] The reactant used in the direct dehydrogenation reaction of n-butane in this example was a C4 mixture including 99.65 wt % of n-butane, and specific composition thereof was presented in the following Table 1.

    TABLE-US-00001 TABLE 1 Composition of the C4 mixture used as a reactant composition molecular formula wt % n-butane C.sub.4H.sub.10 99.65 i-butane C.sub.4H.sub.10 0.27 1-butane C.sub.4H.sub.8 0.03 cis-2-butane C.sub.4H.sub.8 0.05 total 100.00

    [0092] For a catalyst reaction, a linear type quartz reactor was equipped in an electric furnace and packed with said catalyst, and then a reduction process was carried out for catalyst activation before beginning the reaction. In the reduction process, the temperature of the fixed bed reactor was elevated from room temperature to 570 C. and maintained at 570 C. for 3 hours; a gas mixture of hydrogen and nitrogen at a mixing ratio of 1:1 was fed for the reduction process; and the catalyst amount for the reaction was set to make the feeding rate become 600 cc.Math.hr.sup.1.Math.gcat.sup.1 based on hydrogen.

    [0093] Next, the reactor temperature was lowered to 550 C., a C4 mixture comprising n-butane and nitrogen was passed through the catalyst bed to carry out a direct dehydrogenation reaction of n-butane. At this time, as for a gas for the reaction, the ratio of n-butane:nitrogen at a mixing ratio of 1:1 was fed, and the feeding rate was set to be 600 cc.Math.hr.sup.1.Math.gcat.sup.1 based on the adjusted catalyst amount and n-butane.

    [0094] After finishing the reaction, there were: a major product, i.e. C4 olefins such as 1-butene, 2-butene, i-butene and 1,3-butadiene; side products, other than said major product, including those from cracking such as methane, ethane, ethylene, propane, propylene and those from isomerization such as i-butane and the like; and unreached n-butane, and for separating and analyzing them, gas chromatography was used.

    [0095] In a direct dehydrogenation reaction of n-butane on a platinum-tin-zinc-alumina catalyst, the n-butane conversion rate, C4 olefin selectivity and C4 olefin yield were calculated using the following formulas 1 to 3.

    [00001] conversion rate .Math. .Math. ( % ) = mole .Math. .Math. number .Math. .Math. .Math. of .Math. .Math. .Math. reacted .Math. .Math. n .Math. - .Math. butane mole .Math. .Math. .Math. number .Math. .Math. of .Math. .Math. fed .Math. .Math. n .Math. - .Math. butane 100 [ Formula .Math. .Math. 1 ] selectivity .Math. .Math. ( % ) = mole .Math. .Math. number .Math. .Math. of .Math. .Math. produced .Math. .Math. C .Math. .Math. 4 .Math. .Math. olefin mole .Math. .Math. number .Math. .Math. of .Math. .Math. reacted .Math. .Math. n .Math. - .Math. butane [ Formula .Math. .Math. 2 ] yield .Math. .Math. ( % ) = mole .Math. .Math. number .Math. .Math. of .Math. .Math. produced .Math. .Math. .Math. C .Math. .Math. 4 .Math. .Math. olefin mole .Math. .Math. number .Math. .Math. of .Math. .Math. fed .Math. .Math. n .Math. - .Math. butane 100 [ Formula .Math. .Math. 3 ]

    [0096] Direct dehydrogenation reaction was performed on the platinum-tin-zinc-alumina catalyst obtained from the preparation examples 1 and 2 for 360 minutes, and the change in a reactivity throughout the process was shown in Table 2 and the change in C4 olefin yield was shown in FIG. 1. Further, the test results regarding reactivity after 360 minutes of the reaction were shown in Table 3 and FIG. 2.

    TABLE-US-00002 TABLE 2 Change in the reactivity in a direct dehydrogenation reaction of a platinum-tin-zinc-alumina (Pt-Sn-Zn-Al.sub.2O.sub.3) catalyst for 360 minutes reaction n-butane conversion C4 olefin C4 olefin time (min) rate (%) selectivity (%) yield (%) 30 70.2 77.5 50.2 60 65.8 84.5 54.9 90 59.2 87.0 55.5 120 66.2 87.0 56.0 150 64.3 87.1 56.0 180 63.2 88.4 55.9 210 62.3 89.2 55.7 240 61.5 90.1 55.4 270 60.8 90.7 55.1 300 60.2 91.1 54.8 330 59.6 91.5 54.6 360 59.1 91.8 54.3

    TABLE-US-00003 TABLE 3 Reactivity in a direct dehydrogenation reaction of a platinum-tin-zinc alumina (Pt-Sn-Zn-Al.sub.2O.sub.3) catalyst after 360 minutes percent (%) n-butane conversion rate 59.1 selectivity 1-butene 24.2 91.9 2-butene 54.9 i-butene 7.1 1,3-butadiene 5.7 i-butane 1.5 methane 1.1 ethane 1.9 ethylene 0.1 propane 1.1 propylene 0.7 C4 olefin yield 54.3

    [0097] From Tables 2 and 3, and FIGS. 1 and 2, the direct dehydrogenation of n-butane using a PtSnZnAl.sub.2O.sub.3 catalyst showed a tendency of a gradual decrease in activation as time elapses (resulting in a conversion rate and yield decrease), contrarily an increase in selectivity. As it has been reported by various documents, it seemed that inactivation occurred owing to coking deposition. The selectivity for C4 olefins such as 1-butene, 2-butene, i-butene and 1,3-butadiene was as high as about 90% or more, and major side products were shown to be cracking products such as methane, ethane, propane and propylene.

    Example 2

    [0098] The Reactivity of a Platinum-Tin-Alumina Catalyst and Platinum-Tin-Transition Metal-Alumina Catalysts (PtSnAl.sub.2O.sub.3, PtSnCaAl.sub.2O.sub.3, PtSnInAl.sub.2O.sub.3, PtSnLaAl.sub.2O.sub.3, PtSnCeAl.sub.2O.sub.3) Prepared by the Above Preparation Example 3 in a Direct Dehydrogenation Reaction

    [0099] For comparing with the results from the reactivity of direct dehydrogenation reaction of n-butane using the platinum-tin-zinc-alumina (PtSnZnAl.sub.2O.sub.3) catalyst prepared by using conventional alumina carrier (-Alumina) according to Example 1, a direct dehydrogenation reaction of n-butane using the platinum-tin-transit ion metal-alumina catalyst (PtSnAl.sub.2O.sub.3, PtSnGaAl.sub.2O.sub.3, PtSnInAl.sub.2O.sub.3, PtSnLaAl.sub.2O.sub.3, PtSnCeAl.sub.2O.sub.3) prepared by impregnating various transition metals to a conventional alumina (-Alumina) according to Preparation example 3 was carried out after the reduction process according to the sequence of Example 1.

    [0100] The reactivity test results from the present example 2 were shown in Tables 4-9 and FIGS. 1 and 2; change in reactivity throughout the reaction over 360 minutes regarding each catalyst was shown in Table 4 (PtSnAl.sub.2O.sub.3 catalyst), Table 5 (PtSnGaAl.sub.2O.sub.3 catalyst), Table 6 (PtSnInAl.sub.2O.sub.3 catalyst), Table 7 (PtSnLaAl.sub.2O.sub.3 catalyst), Table 8 (PtSnCeAl.sub.2O.sub.3 catalyst); change in C4 olefin, production yield, from said 5 species of catalysts, respectively over the reaction for 360 minutes was shown FIG. 1; and the reactivity results after the reaction for 360 minutes were shown in Table 9 and FIG. 2.

    TABLE-US-00004 TABLE 4 Change in a reactivity in a direct dehydrogenation reaction of a platinum-tin-alumina (Pt-Sn-Zn-Al.sub.2O.sub.3) catalyst for 360 minutes reaction time n-butane conversion C4 olefin C4 olefin (min) rate (%) selectivity (%) yield (%) 30 73.8 75.0 55.4 60 68.9 83.1 57.3 90 65.5 86.3 56.5 120 62.6 88.2 55.2 150 60.4 89.5 54.0 180 58.1 90.4 52.6 210 56.3 91.1 51.3 240 52.8 91.8 48.5 270 51.5 92.2 47.4 300 50.0 92.6 46.3 330 48.9 92.7 45.3 360 48.2 92.9 44.8

    TABLE-US-00005 TABLE 5 Change in a reactivity in a direct dehydrogenation reaction of a platinum-tin-gallium-alumina (Pt-Sn-Zn-Al.sub.2O.sub.3) catalyst for 360 minutes reaction n-butane conversion C4 olefin C4 olefin time (min) rate (%) selectivity (%) yield (%) 30 57.2 82.4 49.5 60 51.7 88.9 46.0 90 45.3 90.6 41.0 120 40.5 91.2 37.0 150 36.4 91.2 33.2 180 32.8 91.3 30.0 210 31.1 91.3 28.5 240 29.2 91.1 25.7 270 27.5 90.9 25.0 300 26.1 90.5 23.6 330 25.0 90.5 22.6 360 24.0 90.1 21.6

    TABLE-US-00006 TABLE 6 Change in a reactivity in a direct dehydrogenation reaction of a platinum-tin-indium-alumina (Pt-Sn-In-Al.sub.2O.sub.3) catalyst for 360 minutes reaction n-butane time conversion rate C4 olefin C4 olefin (min) (%) selectivity (%) yield (%) 30 78.0 74.4 58.1 60 69.7 81.6 56.8 90 71.4 86.0 61.4 120 68.9 87.5 60.3 150 66.7 88.2 58.8 180 64.6 90.1 58.2 210 60.7 91.0 55.2 240 55.1 92.1 50.8 270 55.1 92.2 50.8 300 54.0 92.5 50.0 330 53.0 92.8 49.1 360 51.8 93.0 48.2

    TABLE-US-00007 TABLE 7 Change in a reactivity in a direct dehydrogenation reaction of a platinum-tin-lanthanum-alumina (Pt-Sn-La- Al.sub.2O.sub.3) catalyst for 360 minutes reaction n-butane conversion C4 olefin C4 olefin time (min) rate (%) selectivity (%) yield (%) 30 61.0 78.2 47.7 60 65.8 84.5 54.9 90 59.2 87.0 50.2 120 52.4 89.1 46.6 150 48.1 90.1 43.3 180 45.0 90.3 40.7 210 40.7 90.3 36.8 240 38.1 90.3 34.4 270 35.2 89.8 31.6 300 34.0 89.8 30.5 330 32.6 89.6 29.2 360 30.9 89.3 27.6

    TABLE-US-00008 TABLE 8 Change in a reactivity in a direct dehydrogenation reaction of a platinum-tin-cerium-alumina (Pt-Sn-Ce-Al.sub.2O.sub.3) catalyst for 360 minutes reaction n-butane conversion C4 olefin C4 olefin time (min) rate (%) selectivity (%) yield (%) 30 68.0 76.5 52.0 60 65.8 84.5 54.9 90 59.7 87.0 53.2 120 59.2 88.7 52.5 150 57.0 89.8 51.2 180 55.4 90.4 50.1 210 53.5 91.1 48.7 240 52.0 91.3 47.5 270 50.7 91.5 46.5 300 49.4 91.8 45.3 330 48.4 91.9 44.5 360 47.3 91.9 43.4

    [0101] From Tables 4-9 and FIGS. 1 and 2, in the catalyst activity test performed by using each catalyst, all of the catalysts showed a tendency of a gradual decrease in activation as time elapses (resulting in a conversion rate and yield decrease), contrarily an increase in selectivity. It can be found out that the PtSnAl.sub.2O.sub.3 catalyst prepared by sequentially impregnating zinc, and tin and platinum to a conventional alumina (-Alumina) showed higher activity than other 5 species of catalysts i.e, PtSnAl.sub.2O.sub.3, PtSnGaAl.sub.2O.sub.3, PtSnInAl.sub.2O.sub.3, PtSnLaAl.sub.2O.sub.3, PtSnCeAl.sub.2O.sub.3, and also showed a lower inactivation in the elapse of time. Therefore, the PtSnZnAl.sub.2O.sub.3 catalyst prepared by sequentially impregnating zinc, and tin and platinum to a conventional alumina carrier (-Alumina) according to the present invention was considered to be most suitable for a catalyst for a direct dehydrogenation of n-butane.

    Example 3

    [0102] The Reactivity of a Platinum-Tin-Alkali Metal-Alumina Catalysts (PtSnLiAl.sub.2O.sub.3, PtSnNaAl.sub.2O.sub.3, PtSnKAl.sub.2O.sub.3, PtSnRbAl.sub.2O.sub.3) Prepared by the Above Preparation Example 4 in a Direct Dehydrogenation Reaction

    [0103] A direct dehydrogenation reaction of n-butane using each PtSnLiAl.sub.2O.sub.3, PtSnNaAl.sub.2O.sub.3, PtSnKAl.sub.2O.sub.3 and PtSnRbAl.sub.2O.sub.3 catalyst prepared by sequentially impregnating alkali metal, and tin and platinum to a conventional alumina (-Alumina) according to Preparation example 4 was carried out according to the sequence of Example 1. The reaction results of the present example 3 were shown as change in the yield from a direct dehydrogenation reaction of n-butane, for each catalyst over the elapse of time, in Table 10 and FIG. 3.

    TABLE-US-00009 TABLE 10 Change in the reactivity in a direct dehydrogenation reaction of a platinum-tin-alkali metal- alumina catalysts (PtSnLiAl.sub.2O.sub.3, PtSnNaAl.sub.2O.sub.3, PtSnKAl.sub.2O.sub.3, PtSnRbAl.sub.2O.sub.3, PtSnCeAl.sub.2O.sub.3) catalysts for 360 minutes C4 olefin product yield (%) time(minutes) catalyst 30 60 90 120 150 180 210 240 270 300 330 360 Pt/Sn/Li/Al.sub.2O.sub.3 55.4 57.3 56.5 55.2 54.0 52.6 51.3 48.5 47.4 46.3 45.3 44.3 Pt/Sn/Na/Al.sub.2O.sub.3 58.4 58.9 57.9 55.5 53.6 52.5 50.4 48.3 47.0 46.2 43.9 44.0 Pt/Sn/K/Al.sub.2O.sub.3 60.5 59.6 57.8 55.7 54.1 52.1 50.8 49.8 47.3 47.5 46.4 45.3 Pt/Sn/Rb/Al.sub.2O.sub.3 57.1 57.4 56.5 56.0 55.3 55.0 54 51.9 50.9 50.2 49.5 48.8

    [0104] From Table 10 and FIG. 3, in the direct dehydrogenation of n-butane using a platinum-tin-alkali metal-alumina catalyst prepared by sequentially impregnating an alkali metal (lithium, sodium, potassium, rubidium, respectively), and tin and platinum, the PtSnRbAl.sub.2O.sub.3 catalyst showed a high yield and lower inactivation.

    Example 4 (Comparative Example)

    [0105] The Reactivity of a Platinum-Tin-Alkali Earth Metal-Alumina Catalyst (PtSnMgAl.sub.2O.sub.3, PtSnCaAl.sub.2O.sub.3 and PtSnBaAl.sub.2O.sub.3) Prepared by the Above Preparation Example 5 (Comparative Example) in a Direct Dehydrogenation Reaction

    [0106] A direct dehydrogenation reaction of n-butane using each PtSnMgAl.sub.2O.sub.3, PtSnCaAl.sub.2O.sub.3 and PtSnBaAl.sub.2O.sub.3 catalyst prepared by sequentially impregnating alkali earth metal, and tin and platinum, to a conventional alumina (-Alumina) according to Preparation example 5 was carried out according to the sequence of Example 1. The reaction results of the present example 4 were shown, as change in the yield from a direct dehydrogenation reaction of n-butane, for each catalyst over the elapse of time, in Table 11 and FIG. 4.

    TABLE-US-00010 TABLE 11 Change in the yield of C4 olefin production in a direct dehydrogenation reaction of a platinum-tin-alkali earth metal-alumina (PtSnMgAl.sub.2O.sub.3, PtSnCaAl.sub.2O.sub.3, PtSnBaAl.sub.2O.sub.3) catalysts for 360 minutes Yield of C4 olefin products (%) time (min) catalyst 30 60 90 120 150 180 210 240 270 300 330 360 Pt/Sn/Mg/Al.sub.2O.sub.3 52.9 47.1 40.6 34.7 30.2 27.3 25.2 23.0 21.7 20.3 19.2 18.1 Pt/Sn/Ca/Al.sub.2O.sub.3 61.0 60.2 56.2 32.0 49.0 44.7 42.3 40.4 38.6 37.3 35.8 34.5 Pt/Sn/Ba/Al.sub.2O.sub.3 59.2 58.9 56.1 52.9 47.8 44.4 39.8 37.4 35.4 33.7 31.9 30.6

    [0107] From Table 11 and FIG. 4, it was confirmed that each C4 olefin yield was low, on the whole, in the direct dehydrogenation of n-butane using a platinum-tin-alkali earth metal-alumina catalyst prepared by sequentially applying each magnesium, calcium and barium as an alkali earth metal, tin and platinum. Initial yields thereof were similar to those of the catalysts from preparation example 3 and 4, however it significantly dropped after 360 minutes indicating the significant inactivation.