Catalyst for selective hydrogenation of alkyne and its preparation method and application

Abstract

The application discloses a catalyst for selective hydrogenation of alkyne, a preparation method and application thereof, wherein the catalyst comprises an Al2O3-CuO-TiO2 composite oxide carrier and a main active component Pd and optional auxiliary active components supported thereon, and the auxiliary active components are at least one selected from Ag and Mo. The catalyst has high low-temperature reaction activity and selectivity, the preparation process is simple, the reaction condition is mild, the anti-impurity performance is good, and the catalyst can be stably operated for a long time in production, and thus has industrial application value.

Description

TECHNICAL FIELD

[0001] The present application relates to a catalyst for selective hydrogenation of acetylenes and its preparation method and application. BACKGROUND

[0002] A large amount of C5 fraction is produced as by-product in the process of ethylene production by petroleum cracking, which contains 15% to 25% of isoprene by mass fraction. Isoprene is the main raw material for synthetic rubber. In order to prevent the catalyst from being poisoned in the polymerization of isoprene, the mass fraction of acetylenes in the polymerization grade isoprene product is required to be not more than 5.0 x 10 -5 At present, the extraction distillation method is generally used to remove acetylenes in the C5 fraction to produce polymerization grade isoprene. However, this method has many problems. For example, in the case of the C5 fraction separation device in China, the two-stage extraction distillation method is used to separate and produce polymerization grade isoprene product with dimethylformamide as solvent, in which the second extraction unit has the disadvantages of high energy consumption, large solvent loss, difficult operation and serious environmental pollution.

[0003] If the mass fraction of acetylenes in the material is reduced to 2.5 x 10 -5 below by using the selective hydrogenation technology before the first extraction system, and the cyclopentadiene is removed to a mass fraction of 1 x 10 -6 below by using the reactive distillation technology in the first extraction unit, the second extraction unit can be cancelled, thereby greatly reducing the energy consumption and material consumption.

[0004] In the prior art, the commonly used catalyst is a noble metal selective hydrogenation catalyst prepared by loading a noble metal active component such as a palladium-based catalyst active component on an alumina carrier. The noble metal selective hydrogenation catalyst has high hydrogenation activity and good selectivity, but the cost is increasing, and the anti-impurity ability and stability are not satisfactory. Since the boiling point of small molecules such as carbon disulfide is close to that of C5, the C5 fraction generally contains 10 to 20 ppm of low-carbon sulfur, which easily affects the stability of the palladium-based catalyst. So far, there is no report on the successful industrial application of a palladium-based catalyst in the selective hydrogenation of C5 fraction. Therefore, it has great scientific research value and industrial application value to develop a noble metal catalyst with high low-temperature activity, good selectivity, strong anti-impurity ability and high stability. SUMMARY

[0005] Therefore, in order to overcome at least one of the above problems in the prior art, the present application provides a catalyst for selective hydrogenation of acetylenes and its preparation method and application.

[0006] The purpose of the present application is achieved by the following technical solutions.

[0007] In a first aspect, the present application provides a catalyst for selective hydrogenation of alkyne, wherein the catalyst comprises an Al2O3-CuO-TiO2 composite oxide carrier and a main active component Pd and optional auxiliary active components supported thereon, the auxiliary active components being selected from at least one of Ag and Mo.

[0008] In the present application, by matching the specific carrier, the main active component and the auxiliary active component, a catalyst for selective hydrogenation of alkyne is obtained, which has high low-temperature reaction activity and selectivity.

[0009] According to the present application, the content of CuO is 0.1-5wt%, the content of TiO2 is 5-20wt%, and the content of Al2O3 is 75-94.9wt%, based on the weight of the composite oxide carrier.

[0010] In some embodiments, the content of CuO is 0.3-3wt%, the content of TiO2 is 9-20wt%, and the content of Al2O3 is 77-90.7wt%, based on the weight of the composite oxide carrier.

[0011] According to the present application, the content of the main active component Pd is 0.1-0.5wt% as calculated by palladium oxide, preferably 0.15-0.3wt%, the content of the auxiliary active component is 0.1-4.9wt% as calculated by oxide, preferably 0.1-1.5wt%, and the content of the composite oxide is 95-99.8wt%, preferably 98.2-99.75wt%, based on the total weight of the catalyst.

[0012] According to the present application, the specific surface area of the composite oxide carrier is 30-155m 2 / g, preferably 55-85m 2 / g.

[0013] According to the present application, the pore volume of the composite oxide carrier is 0.2-0.8mL / g, preferably 0.3-0.4m 2 / g.

[0014] According to the present application, the catalyst is a catalyst after activation treatment and passivation treatment.

[0015] In some embodiments, the activation treatment is carried out under hydrogen condition; and in some embodiments, the passivation treatment is carried out under hydrogen atmosphere and / or inert atmosphere, and in the presence of organic nitrogen-containing compounds. The activation treatment and the passivation treatment will be described in more details hereinafter.

[0016] According to the present application, the main active component Pd and the auxiliary active component can each independently exist in the form of an atom or a compound. Such compounds can be compounds of the main active component Pd and compounds of the auxiliary active component commonly used in palladium-based catalysts for selective hydrogenation. In some embodiments, the main active component Pd and the auxiliary active component can each independently exist in the form of an oxide, such as PdO, Ag2O, and MoO3.

[0017] In a second aspect, the present application provides a preparation method of the catalyst of the first aspect, wherein the preparation method comprises the following steps:

[0018] S110, impregnating the Al2O3-CuO-TiO2 composite oxide carrier with a palladium salt solution to obtain an impregnated composite oxide carrier, and drying and calcining the impregnated composite oxide carrier to obtain a catalyst precursor;

[0019] Optionally, S120, impregnating the catalyst precursor with a salt solution of an auxiliary active component to obtain an impregnated catalyst precursor, and drying and calcining the impregnated catalyst precursor to obtain a catalyst.

[0020] According to the preparation method of the present application, the impregnation time in steps S110 and S120 is independently 1-8 hours, preferably 1-4 hours.

[0021] According to the preparation method of the present application, the drying conditions in steps S110 and S120 independently include a drying temperature of 90-120°C and / or a drying time of 2-8 hours.

[0022] According to the preparation method of the present application, the calcination conditions in steps S110 and S120 independently include a calcination temperature of 300-800°C and / or a calcination time of 2-10 hours.

[0023] According to the preparation method of the present application, examples of the palladium salt include, but are not limited to, a sulfate salt, a nitrate salt, a soluble carboxylate salt, and a soluble halide of palladium. In some embodiments, the palladium salt is palladium chloride, palladium nitrate, palladium acetate, or palladium sulfate.

[0024] According to the preparation method of the present application, the type of the palladium salt solution is not particularly limited, and can be an aqueous solution or an organic palladium salt solution formed by using ethanol, benzene, or the like as a solvent. Preferably, the palladium salt solution is an aqueous solution of an inorganic palladium salt. Compared with an organic palladium salt solution, the use of an aqueous solution of a palladium salt is low in cost and environmentally friendly.

[0025] According to the preparation method provided by the application, the concentration of the palladium salt solution is 0.15-0.25 g / ml in terms of palladium.

[0026] According to the preparation method provided by the application, the salt of the promoter component can be a salt of the promoter component commonly used in the field of selective hydrogenation catalysts, examples of which include but are not limited to: nitrate, soluble carboxylate and soluble halide of the promoter component, preferably nitrate, hydrochloride, oxalate or acetate.

[0027] According to the preparation method provided by the application, the type of the salt solution of the promoter component is not particularly limited, which can be an aqueous solution or an organic salt solution formed by using ethanol, benzene or the like as a solvent, preferably an aqueous solution of an inorganic salt of the promoter component, which is low in cost and green in comparison with an organic salt solution. For example, the salt of the promoter component can be silver nitrate or rubidium nitrate.

[0028] According to the preparation method provided by the application, the concentration of the salt solution of the promoter component is 30-60 mg / ml.

[0029] According to the preparation method provided by the application, the preparation method of the composite oxide carrier comprises:

[0030] S210, at a temperature of 50-90℃, the copper salt solution, the titanium salt solution and the alkaline solution are added into the aluminum salt solution in parallel, and after staying at a pH value of 5.5-7.0 for 15-20 min, the alkaline solution is continuously added until the pH value is 8-10, and stays for 15-20 min to obtain a precipitate;

[0031] S220, the precipitate is washed, dried and calcined to obtain the composite oxide carrier.

[0032] In the application, in step S210, the pH value is adjusted to fully mix the several solutions. Further, the alkaline solution is continuously added until the pH value is 8-10 to make the precipitation more thorough and improve the utilization rate of the metal, and at the same time, the pore structure is optimized to obtain a moderate pore volume and specific surface area.

[0033] According to the preparation method provided by the application, the aluminum salt is selected from one or more of aluminum sulfate, aluminum chloride and aluminum nitrate and organic aluminum salt, and / or the concentration of the aluminum salt solution is 0.5-2.5 mol / L.

[0034] According to the preparation method provided by the application, the titanium salt solution is selected from an acid solution of a soluble titanium salt such as metatitanic acid, titanium tetrachloride and tetraethyl titanate, for example, a sulfuric acid solution; and / or the concentration of the titanium salt solution is 0.2-1.2 mol / L.

[0035] According to the preparation method provided by the present application, the copper salt is soluble copper salt, preferably selected from copper chloride, copper sulfate and copper nitrate; and / or the concentration of the copper salt solution is 0.1-1.2 moL / L.

[0036] According to the preparation method provided by the present application, the alkaline solution comprises ammonium salt solution and lye. The ammonium salt is selected from one or more of ammonium bicarbonate, ammonium carbonate and organic ammonium salt; and / or the concentration of the ammonium salt in the alkaline solution is 0.1-0.3 moL / L.

[0037] Similarly, the lye is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide and organic base, and / or the concentration of the lye is 0.2-0.4 moL / L.

[0038] According to the preparation method provided by the present application, the washing process of the precipitate in step S120 comprises washing with deionized water until no acid radical ion is detected.

[0039] According to the preparation method provided by the present application, the drying condition in step S120 comprises drying at a temperature of 100-150℃ for 4-12h.

[0040] According to the preparation method provided by the present application, the calcination condition in step S120 comprises calcination at a temperature of 500-1100℃ for 4-12h.

[0041] According to the preparation method provided by the present application, the preparation method of the titanium salt solution comprises dissolving soluble titanium salt such as metatitanic acid, titanium tetrachloride and tetraethyl titanate in sulfuric acid solution to form the titanium salt solution.

[0042] According to the preparation method provided by the present application, the preparation method further comprises activating the catalyst prepared in step S120.

[0043] In some embodiments, the preparation method further comprises:

[0044] S310, activating the catalyst prepared in step S120 with hydrogen.

[0045] Preferably, the activation condition in step S310 comprises an activation temperature of 300-600℃, an activation pressure of 0-3.0 MPa, a hydrogen flow rate relative to the catalyst of 1-15 mL / min·g, and an activation time of 6-18h.

[0046] In a third aspect, the present application provides the use of the catalyst prepared by the preparation method of the first aspect or the second aspect in acetylene removal in the selective hydrogenation of carbon five alkyne.

[0047] The application provided by the present application, wherein the carbon five alkynes is carbon five alkynes containing raw material.

[0048] In some embodiments, the carbon five alkynes containing raw material comprises 30-80wt% of isoprene, 0.01-1wt% of isoamylenic alkyne, and 0.005-0.1wt% of 2-butyne. Optionally, the carbon five alkynes containing raw material further comprises a balance of mono-olefins and / or alkanes.

[0049] The application provided by the present application, wherein the reaction conditions of the selective hydrogenation include: the reaction temperature is 20-70℃, the reaction pressure is 0.1-1.5MPa, the feed volume space velocity is 0.5-15h -1 The molar ratio of hydrogen to total alkyne in the carbon five alkynes containing raw material is (1.0-4.0):1.

[0050] The present application has the following advantages:

[0051] (1) The catalyst of the present application has high low-temperature reaction activity and selectivity, simple preparation process, mild reaction conditions, good impurity resistance, and can be stably operated for a long time in production, and has industrial application value.

[0052] (2) The Al2O3-CuO-TiO2 composite oxide used in the present application has titanium oxide and aluminum oxide uniformly mixed and enriched on the surface of the composite oxide, and CuO is uniformly dispersed on the composite oxide skeleton structure. And the present inventors surprisingly found that Al2O3, CuO and TiO2 form a strong interaction at high temperature, so the thermal stability of the composite oxide is high, which overcomes the defect that elemental copper is unstable at high temperature. Further, the TiO2 is still able to maintain the active phase of anatase at high temperature of 700-1000℃, ensuring the activity of the catalyst. In addition, it is believed that Al2O3 can maintain the crystal phase of γ-Al2O3, ensuring the crushing strength and pore structure of the catalyst, meeting the needs of industrial application.

[0053] (3) The catalyst for selective hydrogenation of carbon five alkynes provided by the present application has high selectivity and low-temperature activity, large "green oil" capacity, good impurity resistance, stable hydrogenation activity, and can be used for a long period of time, and is a non-noble metal selective hydrogenation catalyst. DETAILED DESCRIPTION

[0054] The present application will be further described below in conjunction with specific examples, but does not constitute any limitation on the present application.

[0055] Example 1

[0056] Preparation of the carrier

[0057] An aluminum sulfate deionized water solution with a concentration of 0.8 mol / L was prepared in 1 L, a metatitanic acid dilute sulfuric acid solution with a concentration of 0.46 mol / L was prepared in 0.5 L, a copper nitrate solution with a concentration of 0.39 mol / L was prepared in 0.1 L, and a mixed alkali solution with pH = 11-12 was prepared by mixing 0.22 mol / L of ammonium bicarbonate solution with 25% ammonia water in 1 L.

[0058] At a temperature of 65°C, the above-mentioned aluminum sulfate deionized water solution was added with the copper nitrate solution and the metatitanic acid dilute sulfuric acid solution in a parallel flow manner, and an appropriate amount of mixed alkali solution was added to keep the pH value of the mixed solution system at 6.2, and the system was kept for 20 min; then the mixed alkali solution was continuously added to make the pH value 9.1, and the system was kept for 20 min to obtain a precipitate, which was filtered to obtain a filter cake.

[0059] The filter cake was repeatedly washed with 20 times the volume of deionized water for 5 times, and the washed filter cake was dried at 110°C for 6 h and calcined at 860°C for 5 h to obtain an Al2O3-CuO-TiO2 composite oxide carrier A.

[0060] Example 2

[0061] An aluminum sulfate deionized water solution with a concentration of 0.88 mol / L was prepared in 1 L, a metatitanic acid dilute sulfuric acid solution with a concentration of 0.35 mol / L was prepared in 0.5 L, a copper nitrate solution with a concentration of 0.2 mol / L was prepared in 0.13 L, and a mixed alkali solution with pH = 11-12 was prepared by mixing 0.22 mol / L of ammonium bicarbonate solution with 25% ammonia water in 1 L.

[0062] At a temperature of 75°C, the aluminum sulfate deionized water solution was added with the copper nitrate solution and the metatitanic acid dilute sulfuric acid solution in a parallel flow manner, and an appropriate amount of mixed alkali solution was added to keep the pH value of the mixed solution system at 6.8, and the system was kept for 15 min; then the mixed alkali solution was continuously added to make the pH value 8.5, and the system was kept for 15 min to obtain a precipitate, which was filtered to obtain a filter cake.

[0063] The filter cake was repeatedly washed with 30 times the volume of deionized water for 7 times, and the washed filter cake was dried at 120°C for 6 h and calcined at 950°C for 4 h to obtain an Al2O3-CuO-TiO2 composite oxide carrier B.

[0064] Example 3

[0065] The steps were basically the same as the preparation method of the carrier in Example 1, except that the concentrations of the solutions were different, specifically, an aluminum sulfate deionized water solution with a concentration of 0.9 mol / L was prepared in 1 L, a metatitanic acid dilute sulfuric acid solution with a concentration of 0.25 mol / L was prepared in 0.5 L, and a copper nitrate solution with a concentration of 0.1 mol / L was prepared in 0.1 L. An Al2O3-CuO-TiO2 composite oxide carrier C was prepared.

[0066] Example 4

[0067] The preparation procedure of the carrier is basically the same as that in Example 1, except that the concentrations of the solutions are different. Specifically, 1 L of aluminum sulfate deionized water solution with a concentration of 0.8 mol / L, 0.5 L of metatitanic acid dilute sulfuric acid solution with a concentration of 0.55 mol / L, and 0.05 L of copper nitrate solution with a concentration of 0.1 mol / L are prepared. The Al2O3-CuO-TiO2 composite oxide carrier D is prepared.

[0068] Comparative Example 1

[0069] 1. Preparation of the carrier

[0070] 1 L of aluminum sulfate deionized water solution with a concentration of 0.8 mol / L is prepared, and 0.56 L of metatitanic acid dilute sulfuric acid solution with a concentration of 0.46 mol / L is prepared. A mixed alkali solution with a pH of 11-12 is prepared by mixing 0.22 mol / L of ammonium bicarbonate solution with 25% ammonia water.

[0071] The three solutions, i.e., the aluminum sulfate deionized water solution, the metatitanic acid dilute sulfuric acid solution, and the mixed alkali solution, are co-precipitated under atmospheric pressure at a temperature of 65°C. The flow rate of the mixed alkali solution is controlled so that the pH value of the precipitate is maintained in the range of 5.0-6.0 for 8 min, then the flow rate of the mixed alkali solution is increased so that the pH value of the mixed solution is maintained in the range of 8.5-9.5 for 8 min, then the flow rate of the mixed alkali solution is reduced so that the pH value of the mixed solution is maintained in the range of 5.0-6.0 for 8 min, and then the flow rate of the mixed alkali solution is increased so that the pH value of the precipitate is maintained in the range of 8.5-9.5. This process is repeated until all the solutions are added. The reaction liquid is allowed to stand at 70°C for 30 min, and then filtered. The filter cake is washed with 15 times the volume of deionized water for 30 min, and then filtered again. This process is repeated four times. Finally, the filter cake is dried at 110°C for 10 h and calcined at 950°C for 5 h to obtain the titanium oxide-aluminum oxide composite E.

[0072] Comparative Example 2

[0073] γ-Al2O3 97 g produced by Yantai Henghui Company is impregnated in 0.1 L of copper nitrate solution with a concentration of 0.38 mol / L for 4 h, dried at 110°C for 8 h, and calcined at 550°C for 5 h. The Al2O3 carrier with a CuO content of 3% is obtained. 3- CuO composite oxide carrier F.

[0074] Comparative Example 3

[0075] γ-Al2O3 produced by Yantai Henghui Company is used as the carrier, which is denoted as carrier G.

[0076] Carrier characterization

[0077] 1. Specific surface area, pore volume

[0078] The specific surface area, pore volume of the support were determined by using ASAP 2020 adsorption instrument (N2adsorption-desorption method) of Micromeritics Instrument Company, USA. Specifically, the support sample was degassed at 623 K for 4 h before testing, and nitrogen was adsorbed at liquid nitrogen temperature, and the sample data were processed using AMS software, and the specific surface area of the sample was obtained using the Brunauer-Emmet-Teller (BET) method. The average pore diameter was obtained from the nitrogen adsorption isotherm using the Barrett-Joyner-Halenda (BJH) method, and the pore volume was obtained from the P / Po single-point desorption curve. The results are shown in Table 1.

[0079] 2. Determination of carrier components

[0080] The components in the support were determined by using UV-2100 ultraviolet spectrophotometer, and the results are shown in Table 1.

[0081] Table 1 Support parameters of Examples 1-4 and Comparative Examples 1-3

[0082]

[0083] Example 5

[0084] 100 g of the Al2O3-CuO-TiO2 composite oxide support A prepared in Example 1 was put into a 60 ml solution of palladium nitrate with a Pd content of 0.21 g, impregnated for 180 minutes, dried at 110°C for 6 hours, and then calcined at 500°C for 4 hours to prepare a catalyst A1 with a Pd content of 0.2 wt%.

[0085] Example 6

[0086] 100 g of the Al2O3-CuO-TiO2 composite oxide support A prepared in Example 1 was put into a 60 ml solution of palladium nitrate with a Pd content of 0.31 g, impregnated for 180 minutes, dried at 110°C for 6 hours, and then calcined at 500°C for 4 hours to prepare a catalyst precursor.

[0087] 100 g of the catalyst precursor was put into a 65 ml aqueous solution of silver nitrate with an Ag content of 0.51 g, impregnated for 1 hour, dried at 110°C for 6 hours, and then calcined at 500°C for 4 hours to prepare a catalyst A2 with a Pd content of 0.3 wt% and an Ag content of 0.5 wt%.

[0088] Example 7

[0089] The catalysts were prepared according to the method of Example 5, except that the composite oxide carrier and the content of the main active component Pd were changed to prepare catalysts B1, C1 and D1, respectively.

[0090] Example 8

[0091] The catalysts were prepared according to the method of Example 6, except that the composite oxide carrier, the content of the main active component Pd, the type and / or content of the auxiliary active component were changed to prepare catalysts B2, C2, D2, A3, B3 and A4, respectively.

[0092] Comparative Example 4

[0093] The catalysts were prepared according to the method of Example 5, except that the composite oxide carrier was changed to prepare catalysts E1, F1 and G1, respectively.

[0094] Comparative Example 5

[0095] The catalysts were prepared according to the method of Example 6, except that the composite oxide carrier was changed to prepare catalysts E2, F2 and G2, respectively.

[0096] Composition of each catalyst in Table 2

[0097]

[0098] Application Example 1

[0099] The catalysts used in this application example were the catalysts prepared in the examples and comparative examples, and were evaluated under the same conditions.

[0100] The reaction conditions for the hydrogenation to remove alkynes were as follows: a trickle-bed hydrogenation reactor with a catalyst loading volume of 100 mL was used, the catalyst loading was 100 mL, the reaction pressure was 1.5 MPa, the reaction temperature was 30°C, the molar ratio of hydrogen to total alkyne in the hydrogenation feedstock was 2.6:1, the feed volume space velocity (the ratio of the amount of liquid feedstock fed per hour to the volume of catalyst loading) was 3.3 h -1 .

[0101] The hydrogenation feedstock was the overhead material of a pre-heavy-removal column in a certain petrochemical cracking C5 fraction separation device (before the first extraction system), and the mass fractions of the components were as follows: isoprene 41.3 wt%, isoamylenes 0.18 wt%, 2-butyne 0.028 wt%, and the remainder was mono-olefins and alkanes.

[0102] The activity of the catalyst was represented by the mass fraction of the residual alkyne after the reaction; the reaction selectivity was represented by the loss rate of isoprene, and the calculation formula was as follows, and the results are shown in Table 3.

[0103] Isoprene loss rate = (mass fraction of isoprene of raw material - mass fraction of isoprene of product) / mass fraction of isoprene of raw material x 100%.

[0104] Table 3 Selective hydrogenation results

[0105]

[0106]

[0107] As can be seen from Table 3, the conversion rate is improved, the olefin is saturated, the acetylene is saturated, and the isoprene loss rate is reduced by using the catalyst provided by the present application to perform the selective hydrogenation reaction of C5 acetylenes, thereby achieving the purpose of canceling the first extraction and reducing the energy consumption and material consumption of the device. In combination with Table 1 and Table 2, it is believed that the Al2O3-CuO-TiO2 composite oxide used in the present application uniformly mixes the titanium oxide and the aluminum oxide and enriches them on the surface of the composite oxide, and the CuO is uniformly dispersed on the framework structure of the composite oxide. At high temperatures, a strong interaction is formed among Al2O3, CuO and TiO2, so that the thermal stability of the composite oxide is high, overcoming the defect that elemental copper is unstable at high temperatures. Further, the TiO2 is still able to maintain the active phase of anatase at high temperatures of 700-1000℃, thereby ensuring the activity of the catalyst.

[0108] Application Example 2

[0109] Stability experiment: A3 catalyst was used under the same process conditions as in Application Example 1, and the same raw material was used. The evaluation results of the catalyst after 800h are as follows.

[0110] Table 4 Selective hydrogenation results

[0111]

[0112] As can be seen from Table 4, the catalyst maintains good running stability in the selective hydrogenation reaction of C5 fractions containing sulfur. The catalyst of the present application has good impurity resistance and can be stably operated for a long time in production, and has industrial application value.

[0113] Any numerical values recited herein include all values from the lower value and up to the upper value. Values that are recited herein also include values that are "framed" by the recited values. For example, if a concentration range is stated as 1% to 50%, it is intended that values such as 25%, 30%, and 35% are expressly enumerated. All integer values are used "open ended" such that "50%" really means "50% to 50%". The same principle applies to ranges recited as being "between" two values. Discrete, non-integer values can be assumed within the stated ranges. These are only a few of the specific examples that are given. In the application, all possible combinations of numerical values between the lowest value and the highest value enumerated, are to be considered to be expressly stated in this application.

[0114] It should be noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present application. While the application has been described with reference to exemplary embodiments, it is understood that the words that have been used herein are words of description, and that they are being used under the descriptive and explanatory privilege intended to aid in the understanding of the application. Modifications can be made to the application in light of the teachings herein, and other steps can be added or deleted thereof without departing from the intended scope of the application. Although the application has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can effect a wide variety of modifications to the preferred embodiments of the application without departing from the scope of the intended application. While the preferred embodiments of the application have been made this description is illustrative and not restrictive. Various modifications can become apparent to those skilled in the art, and the present application is to be limited only by the scope of the appended claims.

Claims

1. A catalyst for the selective hydrogenation of alkynes, wherein, The catalyst comprises an Al2O3-CuO-TiO2 composite oxide support and a main active component Pd supported thereon and an optional co-active component selected from at least one of Ag and Mo. Based on the weight of the composite oxide support, the content of CuO is 1.8~3wt%, the content of TiO2 is 9~20wt%, and the content of Al2O3 is 77~90.7wt%. Based on the total weight of the catalyst, the content of the main active component Pd, calculated as palladium oxide, is 0.1-0.5 wt%; the content of the co-active component, calculated as oxide, is 0.1-4.9 wt%; and the content of the composite oxide is 95-99.8 wt%.

2. The catalyst according to claim 1, characterized in that, Based on the total weight of the catalyst, the content of the main active component Pd, calculated as palladium oxide, is 0.15-0.3 wt%; the content of the co-active component, calculated as oxide, is 0.1-1.5 wt%; and the content of the composite oxide is 98.2-99.75 wt%.

3. The catalyst according to claim 1, characterized in that, The specific surface area of ​​the composite oxide carrier is 30~155 m². 2 / g; And / or, the pore volume of the composite oxide support is 0.2~0.8 mL / g.

4. The catalyst according to claim 3, characterized in that, The specific surface area of ​​the composite oxide carrier is 55-85 m². 2 / g; And / or, the pore volume of the composite oxide support is 0.3-0.4 m³. 2 / g.

5. The catalyst according to any one of claims 1-4, characterized in that, The catalyst is a catalyst that has undergone activation and passivation treatment.

6. The method for preparing the catalyst according to any one of claims 1-5, wherein, The preparation method includes the following steps: S110. The Al2O3-CuO-TiO2 composite oxide support is impregnated with palladium salt solution to obtain the impregnated composite oxide support. The impregnated composite oxide support is then dried and calcined to obtain the catalyst precursor. Optionally, in step S120, the catalyst precursor is impregnated with a salt solution of the co-activating component to obtain an impregnated catalyst precursor, and the impregnated catalyst precursor is dried and calcined to obtain the catalyst.

7. The preparation method according to claim 6, characterized in that, The immersion treatment time in steps S110 and S120 is 1-8 hours each independently; And / or, the drying conditions in steps S110 and S120 each independently include: a drying temperature of 90-120°C; and / or a drying time of 2-8 hours; And / or, the calcination conditions in steps S110 and S120 each independently include: a calcination temperature of 300-800℃; and / or a calcination time of 2-10 hours.

8. The preparation method according to claim 7, characterized in that, The immersion treatment time in steps S110 and S120 is 1-4 hours each independently.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The palladium salt is selected from palladium sulfate, nitrate, soluble carboxylate and soluble halide, and / or, based on PdO, the concentration of the palladium salt solution is 0.15-0.25 g / ml; And / or, the salt of the co-active component is selected from nitrates, soluble carboxylates and soluble halides, and / or, the concentration of the salt solution of the co-active component is 30-60 mg / ml.

10. The preparation method according to claim 9, characterized in that, The preparation method of the composite oxide support includes: S210. At a temperature of 50~90℃, copper salt solution, titanium salt solution and alkaline solution are added to aluminum salt solution in a co-current manner. After standing at a pH value of 5.5~7.0 for 15~20 min, alkaline solution is added until the pH value is 8~10, and then stood at a pH value of 15~20 min to obtain precipitate. S220. The precipitate is washed, dried and calcined to obtain a composite oxide carrier.

11. The preparation method according to claim 10, characterized in that, The aluminum salt is selected from one or more of aluminum sulfate, aluminum chloride, aluminum nitrate, and organoaluminum salts, and / or the concentration of the aqueous solution of the aluminum salt is 0.5~2.5 mol / L.

12. The preparation method according to claim 11, characterized in that, The titanium salt solution is selected from acid solutions of soluble titanium salts such as metatitanic acid, titanium tetrachloride, and tetraethyl titanate; and / or, the concentration of the titanium salt solution is 0.2~1.2 mol / L.

13. The preparation method according to claim 12, characterized in that, The acid solution is a sulfuric acid solution.

14. The preparation method according to claim 10, characterized in that, The copper salt is selected from copper chloride, copper sulfate, and copper nitrate; and / or, the concentration of the aqueous solution of the copper salt is 0.1-1.2 mol / L.

15. The preparation method according to claim 10, characterized in that, The alkaline solution comprises an ammonium salt and an alkaline solution; and / or, the concentration of the ammonium salt in the alkaline solution is 0.1~0.3 mol / L.

16. The preparation method according to claim 15, characterized in that, The ammonium salt is selected from one or more of ammonium bicarbonate, ammonium carbonate, and organic ammonium salts.

17. The preparation method according to claim 10, characterized in that, The drying conditions in step S120 include: a drying temperature of 100~150℃ and a drying time of 4~12h.

18. The preparation method according to claim 17, characterized in that, The calcination conditions in step S120 include: a calcination temperature of 500~1100℃ and a calcination time of 4~12h.

19. The application of the catalyst according to any one of claims 1-5 in the selective hydrogenation of C5 alkynes for alkyne removal.

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