Catalyst for alkyne selective hydrogenation and preparation method and application thereof

Abstract

The invention discloses a catalyst for alkyne selective hydrogenation and a preparation method and application thereof, the catalyst comprises an Al2O3-CuO-TiO2 composite oxide carrier, a main active component Pd and an optional auxiliary active component, the main active component Pd and the optional auxiliary active component are loaded on the Al2O3-CuO-TiO2 composite oxide carrier, and the auxiliary active component is selected from at least one of Ag and Mo. The catalyst provided by the invention has high low-temperature reaction activity and selectivity, is simple in preparation process, mild in reaction condition and good in impurity resistance, can stably operate for a long time in production, and has industrial application value.

Description

Technical Field

[0001] The invention relates to a catalyst for selective hydrogenation of alkynes and a preparation method and application thereof. Background Art

[0002] When petroleum is cracked to produce ethylene, a large amount of C5 fraction is produced as a by-product, which contains 15% to 25% isoprene by mass. Isoprene is the main raw material for synthetic rubber. In order to prevent catalyst poisoning during isoprene polymerization, the mass fraction of alkynes in polymerization-grade isoprene products is required to be no more than 5.0×10 -5 . Currently, the industry generally uses extractive distillation to remove alkynes from the C5 fraction to produce polymerization-grade isoprene. However, this method has many problems. Taking my country's cracking C5 fraction separation device as an example, dimethylformamide is used as a solvent and a two-stage extractive distillation method is used to separate and produce polymerization-grade isoprene products. 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 alkynes in the material is reduced to 2.5×10 -5 Next, in the first extraction unit, reactive distillation technology is used to remove cyclopentadiene to a mass fraction of 1×10 -6 Therefore, the second extraction unit can be eliminated, thereby greatly reducing energy consumption and material consumption.

[0004] In the prior art, 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 is commonly used. The noble metal selective hydrogenation catalyst has high hydrogenation activity and good selectivity, but the cost is increasing day by day, and the ability to resist impurities and stability are not satisfactory. Since the boiling point of small molecular sulfur such as carbon disulfide is close to that of carbon five, the carbon five 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 noble metal palladium-based catalysts in the selective hydrogenation of carbon five fractions. Therefore, the development of a noble metal catalyst with high low-temperature activity, good selectivity, strong ability to resist impurities and high stability has great scientific research value and industrial application value. Summary of the invention

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

[0006] The objectives of the present invention are achieved through the following technical solutions.

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

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

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

[0010] In some embodiments, based on the weight of the composite oxide support, the content of CuO is 0.3-3 wt %, the content of TiO 2 is 9-20 wt %, and the content of Al 2 O 3 is 77-90.7 wt %.

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

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

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

[0014] According to the catalyst provided by the present invention, the catalyst is a catalyst that has been activated and passivated.

[0015] In some embodiments, the activation treatment is carried out under hydrogen conditions; and in some embodiments, the passivation treatment is carried out under a hydrogen atmosphere and / or an inert atmosphere, and in the presence of an organic nitrogen-containing compound. The activation treatment and the passivation treatment will be described in more detail below.

[0016] According to the catalyst provided by the present invention, the main active component Pd and the auxiliary active component can exist in the form of atoms or compounds independently of each other. Such compounds can be compounds of the main active component Pd and 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 exist in the form of oxides independently of each other, such as PdO, Ag2O, MoO3.

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

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

[0019] Optionally, S120, the catalyst precursor is impregnated with a salt solution of an auxiliary active component to obtain an impregnated catalyst precursor, and the impregnated catalyst precursor is dried and calcined to obtain a catalyst.

[0020] According to the preparation method provided by the present invention, the time of the immersion treatment in steps S110 and S120 is independently 1-8 hours, preferably 1-4 hours.

[0021] According to the preparation method provided by the present invention, the conditions for the drying treatment 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 provided by the present invention, the conditions for the calcination treatment 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 provided by the present invention, examples of the palladium salt include, but are not limited to, palladium sulfate, palladium nitrate, soluble carboxylate and soluble halide. In some embodiments, the palladium salt is palladium chloride, palladium nitrate, palladium acetate or palladium sulfate.

[0024] According to the preparation method provided by the present invention, the present invention has no special restrictions on the type of palladium salt solution, which can be an aqueous solution or an organic palladium salt solution formed by ethanol, benzene, etc. as a solvent, preferably 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 present invention, the concentration of the palladium salt solution is 0.15-0.25 g / ml, calculated as palladium oxide.

[0026] According to the preparation method provided by the present invention, the salt of the co-active component can be a salt of the co-active component commonly used in the field of catalysts for selective hydrogenation, examples of which include but are not limited to: nitrates, soluble carboxylates and soluble halides of the co-active component, preferably nitrates, hydrochlorides, oxalates or acetates.

[0027] According to the preparation method provided by the present invention, the present invention has no particular restrictions on the type of salt solution of the auxiliary active component, which can be an aqueous solution or an organic salt solution formed by ethanol, benzene, etc. as a solvent, preferably an inorganic salt solution of the auxiliary active component. Compared with the organic salt solution, the use of the inorganic salt solution is low in cost and green and environmentally friendly. For example, the salt of the auxiliary active component can be silver nitrate or rubidium nitrate.

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

[0029] According to the preparation method provided by the present invention, the preparation method of the composite oxide support comprises:

[0030] S210, adding a copper salt solution, a titanium salt solution and an alkaline solution to an aluminum salt solution in parallel at a temperature of 50 to 90° C., and after staying at a pH value of 5.5 to 7.0 for 15 to 20 minutes, continuing to add an alkaline solution until the pH value reaches 8 to 10, and staying for 15 to 20 minutes to obtain a precipitate;

[0031] S220, washing, drying and calcining the precipitate to obtain a composite oxide support.

[0032] In the present invention, in step S210, by adjusting the pH value, several solutions can be fully mixed. Further, by continuing to add alkaline solution to a pH value of 8 to 10, the precipitation can be more thorough and the utilization rate of the metal can be improved; at the same time, the pore structure can be optimized to obtain a moderate pore volume and specific surface area.

[0033] According to the preparation method provided by the present invention, the aluminum salt is selected from one or more of aluminum sulfate, aluminum chloride, 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 present invention, the titanium salt solution is selected from the acid solution of soluble titanium salts of metatitanic acid, titanium tetrachloride, and tetraethyl titanate, such as 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 invention, the copper salt is a 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 invention, the alkaline solution comprises an ammonium salt solution and an alkaline solution. The ammonium salt is selected from one or more of ammonium bicarbonate, ammonium carbonate and an organic ammonium salt; and / or the concentration of the ammonium salt in the alkaline solution is 0.1 to 0.3 mol / L.

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

[0038] According to the preparation method provided by the present invention, the precipitate washing process in step S120 includes washing with deionized water until acid radical ions are not detected.

[0039] According to the preparation method provided by the present invention, the drying conditions in step S120 include: a drying temperature of 100 to 150° C. and a drying time of 4 to 12 hours.

[0040] According to the preparation method provided by the present invention, the calcination conditions in step S120 include: a calcination temperature of 500 to 1100° C. and a calcination time of 4 to 12 hours.

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

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

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

[0044] S310, using hydrogen to activate the catalyst obtained in step S120.

[0045] Preferably, the conditions for the activation treatment in step S310 include: an activation temperature of 300 to 600° C., an activation pressure of 0 to 3.0 MPa, a flow rate of hydrogen relative to the catalyst of 1 to 15 mL / min·g, and an activation time of 6 to 18 h.

[0046] In a third aspect, the present invention provides the use of the catalyst prepared by the preparation method of the first aspect or the second aspect for removing alkynes in the selective hydrogenation of C5 alkynes.

[0047] According to the application provided by the present invention, the C5acetylene is a C5acetylene-containing raw material.

[0048] In some embodiments, the C5-alkyne feedstock comprises 30-80 wt% of isoprene, 0.01-1 wt% of isopentenyne, and 0.005-0.1 wt% of 2-butyne. Optionally, the C5-alkyne feedstock further comprises the remainder of monoolefins and / or alkanes.

[0049] According to the application provided by the present invention, the reaction conditions of the selective hydrogenation include: reaction temperature of 20-70°C, reaction pressure of 0.1-1.5 MPa, feed volume space velocity of 0.5-15 h -1 The molar ratio of hydrogen to total alkynes in the C5-containing alkyne raw material is (1.0-4.0):1.

[0050] The present invention has the following advantages:

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

[0052] (2) The Al2O3-CuO-TiO2 composite oxide used in the present invention 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. The inventors were surprised to find that a strong interaction is formed between Al2O3, CuO and TiO2 at high temperatures, so the composite oxide has high thermal stability, overcoming the defect that copper alone is unstable at high temperatures. Furthermore, TiO2 can still maintain the active phase of anatase when calcined at a high temperature of 700 to 1000°C, ensuring the activity of the catalyst. In addition, it is believed that Al2O3 can maintain the crystal phase of γ-Al2O3, ensure the crushing strength and pore structure of the catalyst, and meet the needs of industrial applications.

[0053] (3) The catalyst for selective hydrogenation of C5 alkynes provided by the present invention has high selectivity and low-temperature activity, a large amount of "green oil", good impurity resistance, stable hydrogenation activity, and can be used for a long period of time. It is a non-precious metal selective hydrogenation catalyst. DETAILED DESCRIPTION

[0054] The present invention will be further described below in conjunction with specific embodiments, but they do not constitute any limitation to the present invention.

[0055] Example 1

[0056] Preparation of vector

[0057] Prepare 1 L of 0.8 mol / L aluminum sulfate deionized water solution, 0.5 L of 0.46 mol / L metatitanic acid dilute sulfuric acid solution, 0.1 L of 0.39 mol / L copper nitrate solution, mix 0.22 mol / L ammonium bicarbonate solution with 25% ammonia water to prepare 1 L of mixed alkaline solution with a pH of 11-12.

[0058] At a temperature of 65°C, 0.1L of copper nitrate solution and 0.5L of dilute sulfuric acid solution of titanic acid were added to the above-mentioned deionized aluminum sulfate solution in parallel, 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 mixture was kept for 20 minutes; the mixed alkali was continued to be added to make the pH = 9.1, and the mixture was kept for 20 minutes to obtain a precipitate, which was filtered to obtain a filter cake.

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

[0060] Example 2

[0061] Prepare 1 L of 0.88 mol / L aluminum sulfate deionized water solution, 0.5 L of 0.35 mol / L metatitanic acid dilute sulfuric acid solution, 0.13 L of 0.2 mol / L copper nitrate solution, mix 0.22 mol / L ammonium bicarbonate solution with 25% ammonia water to prepare 1 L of mixed alkaline solution with a pH of 11-12.

[0062] At a temperature of 75°C, copper nitrate solution and dilute sulfuric acid solution of metatitanic acid were added to the deionized aluminum sulfate solution in parallel, 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 mixture was kept for 15 minutes; the mixed alkali solution was continued to be added to make the pH value = 8.5, and the mixture was kept for 15 minutes to obtain a precipitate, which was filtered to obtain a filter cake.

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

[0064] Example 3

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

[0066] Example 4

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

[0068] Comparative Example 1

[0069] 1. Preparation of Vector

[0070] 1 L of deionized aluminum sulfate solution with a concentration of 0.8 mol / L was prepared, 0.56 L of dilute sulfuric acid solution of titanic acid with a concentration of 0.46 mol / L was prepared, and 0.22 mol / L ammonium bicarbonate solution was mixed with 25% ammonia water to prepare a mixed alkaline solution with a pH of 11-12.

[0071] Under normal pressure and temperature of 65°C, three solutions of aluminum sulfate deionized water solution, metatitanic acid dilute sulfuric acid solution and mixed alkali solution were co-precipitated. The flow rate of the mixed alkali solution was controlled to keep the pH value of the precipitate in the range of 5.0-6.0 for 8 minutes, and then the flow rate of the mixed alkali solution was increased to keep the pH value of the mixed solution in the range of 8.5-9.5 for 8 minutes, and then the flow rate of the mixed alkali solution was reduced to keep the pH value of the mixed solution in the range of 5.0-6.0 for 8 minutes, and then the flow rate of the mixed alkali solution was increased to keep the pH value of the precipitate in the range of 8.5-9.5, and this process was repeated until all the solutions were added. The reaction solution was allowed to stand at 70°C for 30 minutes, filtered, and the filter cake was washed with deionized water 15 times the volume of the filter cake for 30 minutes, filtered again, and washed again. This process was repeated four times, and finally the filter cake was dried at 110°C for 10 hours and calcined at 950°C for 5 hours to obtain titanium oxide-aluminum oxide composite E.

[0072] Comparative Example 2

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

[0074] Comparative Example 3

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

[0076] Vector characterization

[0077] 1. Specific surface area and pore volume

[0078] The specific surface area and pore volume of the carrier were determined using the ASAP 2020 adsorption instrument (N2 adsorption-desorption method) from Mack Instruments, USA. Specifically, the carrier sample was degassed at 623K for 4 hours before the test, nitrogen was adsorbed at liquid nitrogen temperature, the sample data was processed using AMSM software, and the specific surface area of ​​the sample was obtained using the Brunauer-Emmet-Teller (BET) method. The average pore size was obtained based on the nitrogen adsorption isotherm curve using the Barrett-Joyner-Halenda (BJH) method, and the pore volume was obtained using the P / Po single-point desorption curve. The results are shown in Table 1.

[0079] 2. Determination of carrier components

[0080] UV-2100 ultraviolet spectrophotometer was used to measure the components in the carrier. The results are shown in Table 1.

[0081] Table 1 Carrier parameters of Examples 1 to 4 and Comparative Examples 1 to 3

[0082]

[0083] Example 5

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

[0085] Example 6

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

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

[0088] Example 7

[0089] The catalyst preparation method is the same as that of Example 5, except that the contents of the composite oxide carrier and the main active component Pd are changed to prepare catalysts B1, C1, and D1, respectively.

[0090] Example 8

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

[0092] Comparative Example 4

[0093] The catalyst preparation method is the same as that of Example 5, except that the composite oxide carrier is changed to prepare catalysts E1, F1, and G1 respectively.

[0094] Comparative Example 5

[0095] The catalyst preparation method is the same as that of Example 6, except that the composite oxide carrier is changed to prepare catalysts E2, F2, and G2 respectively.

[0096] Table 2 Composition of each catalyst

[0097]

[0098] Application Example 1

[0099] The catalyst used in this application example is the catalyst prepared in the examples and comparative examples, and the evaluation was carried out under the same conditions.

[0100] The reaction conditions for selective 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 volume was 100 mL, the reaction pressure was 1.5 Pa, the reaction temperature was 30 ° C, the molar ratio of hydrogen to total alkynes in the hydrogenation feed was 2.6:1, and the feed volume space velocity (the volume ratio of the liquid feed volume to the catalyst loading volume per hour) was 3.3 h -1 .

[0101] The hydrogenation feedstock is the top material of the pre-deweighting tower in a petrochemical cracking carbon five fraction separation device (before the first extraction system), and the mass fraction of each component is: isoprene 41.3wt%, isopentenyne 0.18wt%, 2-butyne 0.028wt%, and the remainder is monoolefins and alkanes.

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

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

[0104] Table 3 Selective hydrogenation results

[0105]

[0106]

[0107] As can be seen from Table 3, the selective hydrogenation reaction of carbon pentane alkynes using the catalyst provided by the present invention can improve the conversion rate, saturate alkynes and reduce the loss rate of isoprene, thereby achieving the purpose of eliminating one extraction and reducing the energy and material consumption of the device. Combined with Table 1 and Table 2, it is believed that the Al2O3-CuO-TiO2 composite oxide used in the present invention, titanium oxide and aluminum oxide are uniformly mixed and enriched on the surface of the composite oxide, and CuO is uniformly dispersed on the composite oxide skeleton structure. At high temperatures, Al2O3, CuO, and TiO2 form a strong interaction, so the thermal stability of the composite oxide is high, which overcomes the defect that copper is unstable at high temperatures. Further, the high-temperature roasting of TiO2 at 700 to 1000 ° C can still maintain the active phase of rutile, ensuring the activity of the catalyst.

[0108] Application Example 2

[0109] Stability experiment: Using A3 catalyst, under the same process conditions as Application Example 1, using the same raw material feed, the catalyst evaluation results for 800 hours are as follows.

[0110] Table 4 Selective hydrogenation results

[0111]

[0112] It can be seen from Table 4 that the catalyst maintains good operating stability in the selective hydrogenation reaction of sulfur-containing C5 fraction. The catalyst of the present invention has good impurity resistance, can operate stably for a long time in production, and has industrial application value.

[0113] Any numerical value mentioned in the present invention, if there is only an interval of two units between any minimum value and any maximum value, includes all values ​​from the minimum value to the maximum value each time increasing by one unit. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, time, etc. is declared to be 50-90, in this specification it means that 51-89, 52-88... and 69-71 and 70-71 are specifically listed. For non-integer values, 0.1, 0.01, 0.001 or 0.0001 can be appropriately considered as a unit. These are just some specially specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0114] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein, on the contrary, the present invention can be extended to all other methods and applications with the same functions.

Claims

1. A catalyst for the selective hydrogenation of alkynes, wherein: The catalyst comprises an Al2O3-CuO-TiO2 composite oxide carrier, a main active component Pd and an optional auxiliary active component supported thereon, wherein the auxiliary active component is selected from at least one of Ag and Mo.

2. The catalyst according to claim 1, characterized in that Based on the weight of the composite oxide support, the content of CuO is 0.1-5wt%, the content of TiO2 is 5-20wt%, and the content of Al2O3 is 75-94.9wt%; Preferably, based on the weight of the composite oxide support, the content of CuO is 0.3 to 3 wt %, the content of TiO 2 is 9 to 20 wt %, and the content of Al 2 O 3 is 77 to 90.7 wt %.

3. The catalyst according to claim 1 or 2, characterized in that Based on the total weight of the catalyst, the content of the main active component Pd is 0.1-0.5wt% in terms of palladium oxide, preferably 0.15-0.3wt%; the content of the auxiliary active component is 0.1-4.9wt% in terms of oxide, preferably 0.1-1.5wt%; the content of the composite oxide is 95-99.8wt%, preferably 98.2-99.75wt%.

4. The catalyst according to any one of claims 1 to 3, characterized in that The specific surface area of ​​the composite oxide carrier is 30 to 155 m 2 / g, preferably 55-85m 2 / g; And / or, the pore volume of the composite oxide carrier is 0.2-0.8 mL / g, preferably 0.3-0.4 m 2 / g.

5. The catalyst according to any one of claims 1 to 4, characterized in that The catalyst is a catalyst that has been activated and passivated.

6. The method for preparing the catalyst according to any one of claims 1 to 5, wherein: The preparation method comprises the following steps: S110, impregnating the Al2O3-CuO-TiO2 composite oxide support with a palladium salt solution to obtain an impregnated composite oxide support, and drying and calcining the impregnated composite oxide support to obtain a catalyst precursor; Optionally, S120, the catalyst precursor is impregnated with a salt solution of an auxiliary active component to obtain an impregnated catalyst precursor, and the impregnated catalyst precursor is dried and calcined to obtain a catalyst.

7. The preparation method according to claim 6, characterized in that: The time of the immersion treatment in steps S110 and S120 is independently 1-8 hours, preferably 1-4 hours; And / or, the drying conditions in steps S110 and S120 independently include: The drying temperature is 90-120°C; and / or the drying time is 2-8 hours; And / or, the conditions for the calcination treatment in steps S110 and S120 independently include: a calcination temperature of 300-800° C.; and / or a calcination time of 2-10 hours.

8. The preparation method according to claim 6 or 7, characterized in that: The palladium salt is selected from the group consisting of sulfates, nitrates, soluble carboxylates and soluble halides of palladium, and / or the concentration of the palladium salt solution is 0.15-0.25 g / ml in terms of PdO; 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.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The preparation method of the composite oxide carrier comprises: S210, adding a copper salt solution, a titanium salt solution and an alkaline solution to an aluminum salt solution in parallel at a temperature of 50 to 90° C., and after staying at a pH value of 5.5 to 7.0 for 15 to 20 minutes, continuing to add an alkaline solution until the pH value reaches 8 to 10, and staying for 15 to 20 minutes to obtain a precipitate; S220, washing, drying and calcining the precipitate to obtain a composite oxide support; Preferably, the aluminum salt is selected from one or more of aluminum sulfate, aluminum chloride, aluminum nitrate and organic aluminum salt, and / or the concentration of the aluminum salt aqueous solution is 0.5 to 2.5 mol / L; Preferably, the titanium salt solution is an acid solution of a soluble titanium salt selected from metatitanic acid, titanium tetrachloride, and tetraethyl titanate, such as a sulfuric acid solution; and / or, the concentration of the titanium salt solution is 0.2 to 1.2 mol / L; Preferably, the copper salt is selected from copper chloride, copper sulfate and copper nitrate; and / or, the concentration of the copper salt aqueous solution is 0.1-1.2 mol / L; Preferably, the alkaline solution comprises an ammonium salt and an alkali solution; more preferably, the ammonium salt is selected from one or more of ammonium bicarbonate, ammonium carbonate and an organic ammonium salt; and / or, the concentration of the ammonium salt in the alkaline solution is 0.1 to 0.3 mol / L; Preferably, the drying conditions in step S120 include: a drying temperature of 100 to 150° C. and a drying time of 4 to 12 hours; Preferably, the calcination conditions in step S120 include: a calcination temperature of 500 to 1100° C. and a calcination time of 4 to 12 hours.

10. Use of the catalyst according to any one of claims 1 to 5 for removing alkynes in the selective hydrogenation of C5 alkynes.

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