CN116037084A - Alkyne selective hydrogenation catalyst and preparation method and application thereof - Google Patents

Abstract

The invention provides an alkyne selective hydrogenation catalyst and a preparation method thereof. In the preparation process of the alumina carrier, a certain amount of alpha-Al is added ₂ O ₃ Powder, alpha-Al used ₂ O ₃ The particle size, impurity content and the like of the powder are required to meet certain conditions. The prepared alumina carrier has the advantages of low bulk density, high water absorption, large pore volume and large average pore diameter. Because the pore volume of the alumina carrier is increased and the water absorption rate is increased, the active metal Pd can be more uniformly distributed on the surface of the alumina carrier, thereby forming a Pd catalyst with high dispersity, and meanwhile, because the pore diameter is increased, the alkene generated by alkyne selective hydrogenation can be more rapidly diffused, thereby avoiding the alkane from being excessively hydrogenated and having better selectivity.

Description

A kind of alkyne selective hydrogenation catalyst and its preparation method and application

technical field

The invention belongs to the field of catalysts, and in particular relates to an alkyne selective hydrogenation catalyst and its preparation method and application.

Background technique

In the ethylene production unit, the cracked gas is separated by rectification to obtain a carbon distillate rich in ethylene, ethane and acetylene, and a carbon distillate rich in propane, propylene, propyne and propadiene (the two are often collectively called MAPD). The three fractions, in which acetylene, propyne and propadiene are impurities in the carbon 2 and carbon 3 fractions, will increase the consumption of subsequent polymerization catalysts and affect the performance of polymer products. In the industry, these alkynes are removed by selective hydrogenation, and at the same time, the production of olefins can be increased and the utilization rate of resources can be improved.

Generally, the alkyne selective hydrogenation catalyst is a supported metal catalyst, which consists of a carrier, a main active component and a co-active component. The commonly used carrier is alumina with different structures and different specific surface areas. The main active component is Pd metal with hydrogenation catalytic activity, and Cu, Ag, Au, etc. are often selected as auxiliary active components. Its preparation mostly adopts impregnation-roasting method, that is, the solution containing active components (mostly salt solution) is fully contacted with the prepared carrier, so that the active components are loaded on the carrier, and after drying, it is roasted at high temperature to decompose the metal salt. for the corresponding oxides. The active components in the calcined catalyst usually exist in the form of oxides, which are used for hydrogenation after reduction with hydrogen.

In the catalyst preparation process, the physical properties and microstructure of the alumina support have a great influence on the performance of the catalyst, and many related studies have been carried out. Chinese patent CN101062483A discloses a catalyst preparation method using porous metal as a carrier. After forming a dense oxide layer on the surface of the porous metal, the sol of inorganic oxide is coated, and after drying and roasting, the carrier intermediate layer is formed, and then the metal active component is loaded. , due to the use of porous metal as the substrate, the catalyst has good thermal conductivity, which can quickly transfer the exothermic heat of the reaction and avoid the catalyst bed overheating.

Chinese patent CN106669850A discloses a preparation method of alumina carrier, which uses pseudo-boehmite modified by chloroaluminate as raw material, and adds boric acid or phosphoric acid compound, alkyl chloride and binder, and after mixing uniformly Extrusion-forming-drying and calcining to obtain macroporous alumina carrier. The carrier prepared by this method has a large pore size and a double pore distribution.

U.S. Patent No. 6,794,552 discloses a method for modifying an alumina carrier, using molten zinc nitrate or magnesium nitrate to impregnate a thermal alumina carrier, forming a Zn-Al or Mg-Al spinel structure on the surface of the alumina carrier, and then loading Metal active components such as Pd, due to the special surface structure of the alumina carrier, the prepared catalyst is used for the selective hydrogenation of alkynes, and has good selectivity.

The existing technical scheme for improving the performance of alkyne selective hydrogenation catalysts by optimizing the preparation method of alumina supports has a long and complicated preparation process and high production costs, and the physical properties of different batches of alumina supports are not stable enough, resulting in poor catalyst performance. Stablize. It is still necessary to develop catalysts for the selective hydrogenation of alkynes with simple preparation methods, less fluctuations in performance, and better selectivity.

Contents of the invention

In order to solve the above-mentioned technical problems, the present invention proposes a catalyst for the selective hydrogenation of alkynes, which is obtained by improving the preparation method of alumina carrier. In the preparation process of alumina carrier, a certain amount of α-Al ₂ O ₃ powder is added, and the particle size and impurity content of the α-Al ₂ O ₃ powder used must meet certain conditions. The prepared alumina carrier has the advantages of low bulk density, high water absorption, large pore volume and average pore diameter. Due to the increase in the pore volume and water absorption of the alumina support, the active metal Pd can be more uniformly distributed on the surface of the alumina support, thereby forming a highly dispersed Pd catalyst. At the same time, due to the increase in the average pore size, the selective hydrogenation of alkynes can generate alkenes faster. Diffusion, avoiding excessive hydrogenation to alkanes, better selectivity.

One of the objectives of the present invention is to provide a catalyst for the selective hydrogenation of alkynes, comprising the main active component Pd, an optional metal-promoting active component and an alumina support, wherein the water absorption of the alumina support is 40- 70%, the pore volume is 0.6-0.9ml/g, and the most probable pore diameter is 0.100-0.300μm.

Preferably, the metal-promoting active component is selected from at least one of Ag, Bi, Cu, Au, Pb, Zn, Ga, preferably at least one of Ag, Bi, Zn, Ga;

In terms of mass percentage, in the catalyst, the Pd content of the main active component is 0.02-0.3%, and the content of the metal-promoting active component is 0-0.6%, preferably 0-0.3%;

The water absorption rate of the alumina carrier is 50-65%, the pore volume is 0.63-0.8ml/g, and the most probable pore diameter is 0.120-0.250μm;

The specific surface area of the alumina support is 5-120m ² /g, the bulk density is 0.3-0.9g/ml, and the strength is 20-200Nm; preferably, the specific surface area of the alumina support is 20-100m ² /g , the bulk density is 0.5~0.8g/ml, the strength is 30~100Nm;

The alumina support also contains 0.01-1 wt% of alkali metal elements, alkaline earth metal elements and/or rare earth metal elements to further improve its strength, specific surface area, pore volume and the like. Wherein, the alkali metal element is selected from at least one of Na, K, Li; the alkaline earth metal element is selected from at least one of Mg, Ca; the rare earth metal element is selected from La, Ce, At least one of Pr and Y, preferably at least one selected from La and Ce.

The second object of the present invention is to provide a method for preparing the above-mentioned alkyne selective hydrogenation catalyst, comprising loading the components comprising the main active component Pd and the metal-promoting active component on the oxidation catalyst. The alkyne selective hydrogenation catalyst is obtained on an aluminum carrier. Preferably, the preparation method specifically includes: immersing the components including the alumina carrier in a metal compound solution containing a Pd compound and a metalloproximate compound After drying and roasting, the catalyst for the selective hydrogenation of alkynes is obtained.

specifically,

The Pd compound is selected from soluble compounds of metal Pd, preferably selected from at least one of palladium nitrate, palladium chloride, and palladium acetate;

The metal-helping compound is selected from at least one of the chlorides, nitrates, and acetates of Ag, Bi, Cu, Au, Pb, Zn, and Ga, preferably selected from the chlorides of Ag, Bi, Zn, and Ga , at least one of nitrates;

Based on the saturated water absorption of the alumina support, the amount of the metal compound solution used is 40-90%, preferably 40-70%, of the saturated water absorption of the alumina support.

In the above preparation method, the metal compound solution can be loaded onto the carrier by impregnation methods commonly used in the art, such as spray coating, equal volume impregnation or supersaturated impregnation. When loading multiple metal-promoting active components, a one-step loading method or a step-by-step loading method can be used. The one-step loading method is to divide two or more metal-promoting active components into a mixed solution, and then load them on the carrier in one step; the step-by-step loading method is to prepare several active component precursors into solutions and load them on the carrier separately. , After each load, it needs to be dried and roasted before the next load.

In the above preparation method, there are no special requirements for drying and roasting conditions, and common drying and roasting conditions in this field can be used. Preferably, the drying temperature is 40-150° C., and the drying time is 4-48 hours; preferably, the The drying temperature is 50-120°C, and the drying time is 8-24 hours; the roasting time is different according to the content of the metal active component, and the content of the metal active component increases, and the roasting time can be increased accordingly. Specifically, the The calcination time is 2-15 hours, preferably 3-9 hours; the calcination temperature is 300-500°C.

In the above preparation method, the preparation method of the alumina carrier includes the steps of powder mixing, kneading and molding, and drying and roasting, specifically including the following steps:

Step 1. Mix the components including alumina powder and additives evenly to obtain the powder to be kneaded;

Step 2, adding the acidic aqueous solution to the above-mentioned powder to be kneaded for kneading and molding;

Step 3. After drying and calcining the kneaded product, the alumina carrier is obtained.

In the above step 1, the alumina powder includes pseudo-boehmite powder, α-Al ₂ O ₃ powder, and optionally alumina trihydrate powder and/or de-alumina powder.

Wherein, the pseudo-boehmite powder can be commonly used pseudo-boehmite, preferably, the specific surface area of the pseudo-boehmite powder is 200-300m ² /g, and the pore volume is 0.5-1.2ml /g, bulk density 0.2～0.4g/ml.

The α-Al ₂ O ₃ powder can be obtained by roasting high-purity aluminum hydroxide. The roasting temperature should be greater than 1300°C. During the roasting process, fluorine-containing compounds can be added to form flaky alumina particles. At this time, the α-Al ₂ O ₃ powder The F content in the body is not more than 0.1%; the α-Al ₂ O ₃ powder can also be obtained by roasting the pseudo-boehmite powder used for molding, and the roasting temperature should be greater than 1300°C. Preferably, in the α-Al ₂ O ₃ powder, the content of α-Al ₂ O ₃ is greater than 95%, the particle size of the powder is 2-100 μm, and the mass content of Na, Fe and Si is less than 0.1%. The α-Al ₂ O ₃ powder is 5-30 wt%, preferably 5-20 wt%, of the total weight of the alumina powder.

Both the alumina trihydrate and fast dealumina can be selected from commonly used components, for example, the alumina trihydrate powder can be selected from at least one of gibbsite, bayerite, and gibbsite , the fast de-alumina powder is obtained by rapid dehydration of aluminum hydroxide, wherein the mass content of Na and Fe is less than 0.1%; the mass of the alumina trihydrate powder accounts for 0% to 10% of the total mass of the alumina powder; The mass of the fast de-alumina powder accounts for 0-10% of the total mass of the alumina powder.

In the above step 1, the additive is at least one selected from silicon-containing compounds and forming pore-forming aids, and the amount of the additive is 0-20% of the total mass of the alumina carrier, preferably 0-10%. Wherein, the silicon-containing compound is selected from water-insoluble silicon-containing compounds, preferably at least one selected from dry silica gel, nano-silicon oxide, and silicon carbide; wherein, the preferred average particle size of nano-silicon oxide and dry silica gel is less than 120nm . The forming pore-forming auxiliary agent is selected from at least one of natural organic matter, high molecular polymer, and decomposable basic compound, preferably selected from the group consisting of turnip powder, starch, methylcellulose, and hydroxypropylmethylcellulose Sodium hydroxymethyl cellulose, polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol, polyacrylate acrylic acid, urea, methylamine, At least one of ethylenediamine, ammonium carbonate, and ammonium bicarbonate; those skilled in the art can select one or more forming pore-forming aids based on experience.

In the above step 2, the acid in the acidic aqueous solution is selected from at least one of organic acids, inorganic acids, and acidic salt compounds, preferably selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, and phosphoric acid. At least one of ammonium hydrogen; the mass percent concentration of the acid in the acidic aqueous solution is 0.1-10%, preferably 0.1-5%. The weight ratio of the acidic aqueous solution to the powder to be kneaded is 0.5-5:1, preferably 0.6-2:1. Those skilled in the art can adjust the amount of acid in the acidic aqueous solution according to the plasticity of the kneaded billet and the specific surface area, strength, and bulk density of the carrier after high-temperature roasting.

A soluble additive is also added to the acidic aqueous solution, and the soluble additive is selected from at least one of alkali metal compounds, alkaline earth metal compounds, and rare earth metal compounds. Wherein, the alkali metal compound is selected from the inorganic salt compounds of metal Na, K, Li, preferably selected from at least one of the nitrates and chlorides of metal Na, K, Li; the alkaline earth metal compound is selected from the metal Mg , Ca inorganic salt compound, preferably at least one selected from metal Mg, Ca nitrate, chloride; the rare earth metal compound is selected from soluble rare earth metal salt compounds, preferably selected from La, Ce, Pr, Y At least one of nitrates and chlorides, more preferably at least one of nitrates and chlorides selected from La and Ce; in terms of the mass percentage of metal elements, the metal in the soluble additive accounts for The total amount of alumina powder used is 0-1.35%, preferably 0-0.9%.

In the above step 3, the drying temperature is 60-150°C, and the drying time is 3-48 hours; the calcination temperature is 800-1200°C, and the calcination time is 3-48 hours; during the calcination process, when the temperature is below 500°C, The heating rate is 30-150°C/h, and when the temperature is above 500°C, the heating rate is 100-280°C/h.

The third object of the present invention is to provide the above-mentioned alkyne selective hydrogenation catalyst or the alkyne selective hydrogenation catalyst prepared by the above-mentioned preparation method, which is used for the alkyne hydrogenation reaction.

According to a specific embodiment of the present invention, the catalyst is first reduced before use, preferably, the reduction conditions are: the reducing atmosphere is an atmosphere with a hydrogen content of not less than 50%, and the reduction reaction temperature is 80-200°C , The reduction reaction time is 2 to 12 hours;

When the catalyst is used for the selective hydrogenation reaction of the carbon distillate, the percentage of acetylene in the carbon distillate is 1.0-5.0%, the reaction temperature is 20-120°C, and the reaction space velocity is 3000-12000h ^-1 ; or,

When the catalyst is used for the selective hydrogenation reaction of the C3 fraction, the percentage content of propyne and propadiene in the C3 fraction is 1.0-5.0%, the reaction temperature is 30-70°C, and the reaction space velocity is 20-120h ^{- 1} .

In the present invention, α-Al ₂ O ₃ powder is added during the preparation process of the alumina carrier, so that the alumina carrier with larger pore volume, pore diameter and water absorption rate and smaller bulk density can be obtained. On the alumina carrier, Pd active components, Ag, Au, Zn and other co-active components are supported, and after proper drying and roasting steps, a catalyst for the selective hydrogenation of alkynes with stable performance and better selectivity can be obtained.

Detailed ways

The present invention is specifically described below in conjunction with specific embodiment, it is necessary to point out here that following embodiment is only used for the further description of the present invention, can not be interpreted as the restriction to protection scope of the present invention, those skilled in the art can understand the present invention according to the content of the present invention Some non-essential improvements and adjustments made by the invention still belong to the protection scope of the present invention.

The test instrument and test conditions adopted in the embodiment are as follows:

The specific surface area is measured by nitrogen physical adsorption BET method;

The bulk density is calculated by measuring the mass of 100mL alumina carrier, and the average value is taken after measuring 3 times for each sample;

The pore volume and most probable pore diameter are measured by mercury porosimetry, referring to the general alumina carrier pore volume measurement method;

The strength is measured by a general-purpose particle strength measuring instrument, and the average value of the measurement results of 20 carriers is taken;

The water absorption rate is obtained by taking 20g of the alumina carrier, soaking it in water for 10 minutes, taking it out and draining the surface water, and measuring the weight gain.

Example 1

Alumina carrier preparation method: Weigh 180g of pseudoboehmite powder, 20g of α-Al ₂ O ₃ powder, 8g of turnip powder, and 10g of starch, mix them uniformly in a mixer, and transfer them to a kneader. Among them, the specific surface area of pseudo-boehmite powder is 252.4m ² /g _, the pore volume is _0.944ml /g, and the bulk density is 0.33g/ml; The resulting α-Al ₂ O ₃ content is 98.0%, the average particle size is 5 μm, and the mass content of Na, Fe and Si is less than 0.01%. Weigh 2.00g of concentrated nitric acid, 2.00g of acetic acid, and 1.517g of lanthanum nitrate, add them into 200g of deionized water, and prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. After baking at 120°C for 12hrs, bake at 1175°C for 6hrs, control the heating rate at 100°C/hr when the temperature is below 600°C, and control the heating rate at 200°C/hr when the temperature is above 500°C, to obtain an alumina carrier with a La loading of 0.35% .

Active metal loading method: Measure 5 mL of palladium nitrate solution containing 10 mg Pd/mL, weigh 0.079 g of silver nitrate into the palladium nitrate solution, dilute to 58 mL with deionized water, and spray onto 100 g of alumina carrier. The sprayed sample was dried at 120° C. for 6 hours and calcined at 500° C. for 8 hours to obtain catalyst S1 with a Pd content of 0.05% by mass and an Ag content of 0.05% by mass.

Example 2

Alumina carrier preparation method: Weigh 150g of pseudoboehmite powder, 50g of α-Al ₂ O ₃ powder, 6g of turnip powder, 5g of starch, and 3g of cross-linked polyethylene microspheres with a particle size of about 40 microns, and place them in a mixer Mix well and transfer to a kneader. Among them, the specific surface area of pseudo-boehmite powder is 252.4m ² /g, the pore volume _{is 0.944ml} /g, and the bulk density is 0.33g/ml; The resulting α-Al ₂ O ₃ content is 99.5%, the average particle size is 12 μm, and the mass content of Na, Fe and Si is less than 0.01%. Weigh 3.00 g of concentrated nitric acid and 1.745 g of cerium nitrate, add them into 200 g of deionized water, and prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying conditions were the same as in Example 1, the heating process of calcination was the same as in Example 1, and the calcination temperature was 1165° C. to obtain an alumina carrier with a Ce loading of 0.40%.

Active metal loading method: measure 5 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute it to 58 mL with deionized water, spray it on 100 g of alumina carrier, dry at 120 °C for 6 h, and roast at 500 °C for 8 h to obtain the Pd-containing catalyst front body. Weigh 0.110g of silver nitrate and 0.045g of zinc nitrate, prepare a 58mL solution with deionized water, spray on 100g of the Pd-containing catalyst precursor prepared above, dry at 120°C for 6h, and roast at 500°C for 8h to obtain catalyst S2. The Pd content was 0.05% by mass, the Ag content was 0.07% by mass, and the Zn content was 0.01% by mass.

Example 3:

Alumina carrier preparation method: Weigh 170g of pseudoboehmite powder, 20g of α-Al ₂ O ₃ powder, 10g of alumina trihydrate powder, 6g of turnip powder, and 5g of urea, mix them evenly in a mixer, and transfer to in a kneader. Among them, the specific surface area of pseudo-boehmite powder is 257.9m ² /g, the pore volume _{is 1.16ml} /g, and the bulk density is 0.23g/ml; The particle size is 75 μm, the content of α-Al ₂ O ₃ is 99.5%, and the mass content of Na, Fe and Si is about 0.05%. Same as Example 1. Weigh 2.00 g of concentrated nitric acid, 1 g of acetic acid, and 1.517 g of lanthanum nitrate, add them into 190 g of deionized water, and prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying conditions were the same as in Example 1, the calcination procedure was the same as in Example 1, and the calcination temperature was 1180° C. to obtain an alumina carrier with a La loading of 0.35%.

Active metal loading method: measure 5 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute it to 58 mL with deionized water, spray it on 100 g of alumina carrier, dry at 120 °C for 6 h, and roast at 500 °C for 8 h to obtain the Pd-containing catalyst front body. Weigh 0.146g of chloroauric acid, prepare a 58mL solution with deionized water, spray it onto 100g of the Pd-containing catalyst precursor prepared above, dry at 120°C for 6h, and roast at 500°C for 8h to obtain catalyst S3 with a Pd content of 0.05 % by mass, and the Au content was 0.07% by mass.

Example 4:

Alumina carrier preparation method: Weigh 170g of pseudoboehmite powder, 20g of α-Al ₂ O ₃ powder, 10g of fast dealumina powder, 6g of turnip powder, and 6g of starch, mix them evenly in a mixer, and transfer to in a kneader. The physical properties of the pseudo-boehmite powder are the same as in Example 1; the α-Al ₂ O ₃ powder is obtained by roasting high-purity aluminum hydroxide at 1500°C, and ammonium fluoride is added during the roasting process to form the α-Al ₂ O ₃ powder The crystal grains are flaky, with an average particle size of 51 μm, a content of α-Al ₂ O ₃ of 99.5%, and a mass content of Na, Fe, and Si of about 0.05%. Weigh 2.00 g of concentrated nitric acid, 1 g of acetic acid, and 8.936 g of magnesium nitrate, add them into 190 g of deionized water, and prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying conditions were the same as in Example 1, the roasting procedure was the same as in Example 1, and the roasting temperature was 1180° C. to obtain an alumina carrier with a Mg loading of 0.60%.

Active metal loading method: Measure 5 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute to 58 mL with deionized water, add 0.079 g of silver nitrate, spray on 100 g of alumina carrier, dry at 120 ° C for 6 h, and bake at 500 ° C for 8 h , to obtain a Pd-containing catalyst precursor. Weigh 0.052g of gallium nitrate, use deionized water to prepare a 58mL solution, add a small amount of dilute nitric acid to promote dissolution, spray on 100g of the Pd-containing catalyst precursor prepared above, dry at 120°C for 6h, and roast at 500°C for 8h to obtain the catalyst S4 has a Pd content of 0.05% by mass, an Ag content of 0.04% by mass, and a Ga content of 0.01% by mass.

Comparative example 1:

Alumina carrier preparation method: Weigh 200g of pseudoboehmite powder, 8g of turnip powder, and 4g of starch, mix them uniformly in a mixer, and transfer them to a kneader. Among them, the specific surface area of pseudo-boehmite powder is 189.9m ² /g, the pore volume is 0.804ml/g, and the bulk density is 0.25g/ml. Weigh 2.80 g of concentrated nitric acid and add it into 200 g of deionized water to prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying conditions were the same as in Example 1, the calcination procedure was the same as in Example 1, and the calcination temperature was 1195° C. to obtain an alumina carrier.

Active metal loading method: Measure 5 mL of palladium nitrate solution containing 10 mg Pd/mL, weigh 0.016 g of silver nitrate and add it to the palladium nitrate solution, dilute to 58 mL with deionized water, and spray onto 100 g of alumina carrier. The sprayed sample was dried at 120° C. for 6 hours and calcined at 500° C. for 8 hours to obtain a catalyst D1 with a Pd content of 0.05% by mass and an Ag content of 0.01% by mass.

Comparative example 2:

Alumina carrier preparation method: Weigh 190g of pseudoboehmite powder, 10g of α-Al ₂ O ₃ powder, 8g of turnip powder, and 4g of starch, mix them evenly in a mixer, and transfer them to a kneader. The physical properties of the pseudo-boehmite powder are the same as in Comparative Example 1. The α-Al ₂ O ₃ powder is obtained by roasting ordinary aluminum hydroxide at 1300°C. The average particle size is 4 μm, and the α-Al ₂ O ₃ content is 93.9%. The mass content is 0.2%, and the Na and Fe mass content are about 0.1%. Weigh 2.80 g of concentrated nitric acid and add it into 200 g of deionized water to prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying and roasting conditions were the same as in Comparative Example 1 to obtain an alumina carrier.

Active metal loading method: same as Comparative Example 1.

Experimental example 1:

The above catalysts S1～S4, D1～D2 were subjected to the carbon 2 selective hydrogenation evaluation experiment, and the reaction conditions were as follows:

5ml of the catalyst was loaded into a 316L stainless steel reaction tube, and after being replaced with nitrogen, the reaction raw materials were passed into the reactor. The reaction raw material composition (mole fraction) is: hydrogen 0.6%, acetylene 0.4%, ethane 6.56%, ethylene 92.44%. The reaction pressure is 1MPa, the reaction temperature is 90°C, and the reaction space velocity is 8000hr ^-1 . The experimental results are shown in Table 1.

Table 1. Embodiment 1～4 and comparative example 1～2 obtain the catalytic reaction performance of catalyst

selectivity (%) Acetylene content at reactor outlet (μg/g) S1 53 55 S2 58 42 S3 47 60 S4 56 46 D1 35 79 D2 40 68

Example 5:

Alumina carrier preparation method: same as embodiment 1.

Active metal loading method: Measure 25 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute to 58 mL with deionized water, and spray onto 100 g of alumina carrier. The sprayed sample was dried at 120° C. for 6 hours and calcined at 550° C. for 8 hours to obtain catalyst S5 with a Pd content of 0.25% by mass.

Embodiment 6:

Alumina carrier preparation method: weigh 188g pseudo-boehmite powder, 12g α-Al ₂ O ₃ powder, 8g scallop powder, 2g cellulose, 3g ammonium carbonate, mix them evenly in a mixer, and transfer them to a kneader . The pseudo-boehmite powder has a specific surface area of 245.7m ² /g, a pore volume of 0.869ml/g, and a bulk density of 0.22g/ml; the α-Al ₂ O ₃ powder is the same as that in Example 1. Weigh 1.00 g of concentrated nitric acid, 3 g of acetic acid, and 0.365 g of potassium nitrate, add them into 200 g of deionized water, and prepare a mixed solution. The above mixed solution is added to the uniformly mixed powder, fully kneaded, extruded and cut into pellets to obtain toothed spherical particles with a particle diameter of 4-6mm. The drying and roasting conditions were the same as in Example 1 to obtain an alumina carrier with a K loading of 0.10%.

Active metal loading method: Measure 25 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute to 58 mL with deionized water, spray on 100 g of alumina carrier, dry at 120 ° C for 6 h, and roast at 550 ° C for 8 h to obtain the Pd-containing catalyst front body. Weigh 0.209g of chloroauric acid, use deionized water to prepare 58mL solution, spray on 100g of the Pd-containing catalyst precursor prepared above, dry at 120°C for 6h, and roast at 550°C for 8h to obtain catalyst S6 with a Pd content of 0.25 % by mass, and the Au content was 0.1% by mass.

Embodiment 7:

Alumina carrier preparation method: same as embodiment 4.

Active metal loading method: Measure 25 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute to 58 mL with deionized water, spray on 100 g of alumina carrier, dry at 120 ° C for 6 h, and roast at 550 ° C for 8 h to obtain the Pd-containing catalyst front body. Weigh 0.259g of gallium nitrate, prepare a 58mL solution with deionized water, add a small amount of dilute nitric acid to promote dissolution, spray on 100g of the Pd-containing catalyst precursor prepared above, dry at 120°C for 6h, and roast at 500°C for 8h to obtain the catalyst S7 has a Pd content of 0.25% by mass and a Ga content of 0.05% by mass.

Comparative example 3:

Alumina carrier preparation method: same as Comparative Example 1.

Active metal loading method: Measure 35 mL of palladium nitrate solution containing 10 mg Pd/mL, dilute to 58 mL with deionized water, and spray onto 100 g of alumina carrier. The sprayed sample was dried at 120° C. for 6 hours and calcined at 550° C. for 8 hours to obtain catalyst D3 with a Pd content of 0.35% by mass.

Experimental example 2:

The above-mentioned catalysts S5-S7, D3 were subjected to the selective hydrogenation side-line experiment of carbon three fractions propyne and propadiene. The reaction conditions were as follows: 92ml catalyst was packed into a stainless steel tube reactor, and after being replaced with nitrogen, the reaction raw materials were hydrogenated and passed through into the reactor. The composition (mole fraction) of the reaction raw materials is 4.99% propane, 92.3% propylene, 1.19% propadiene, 1.39% propyne, the content ratio of hydrogen to alkyne is about 1.4-1.6, and the experimental space velocity is 70h ^-1 , after 100hr After the reaction, the reaction results are as follows in Table 2:

Table 2. Embodiment 5～7 and comparative example 3 obtain the catalytic performance of catalyst

catalyst MAPD conversion rate (%) MAPD selectivity (%) S5 99.1 71 S6 98.7 74 S7 99.5 75 D3 97.4 63

The physical properties of the alumina carrier used in the above-mentioned embodiments and comparative examples are shown in Table 3 below:

Table 3. The physical property data of alumina carrier in the embodiment and comparative example

According to the physical property data table of the alumina carrier, the S1～S4 and S6 alumina carriers prepared by the method of the present invention have high water absorption rate, large pore volume and most probable pore diameter, and the S1～S4 and S6 alumina carriers have been tested. The specific surface area is 20-50m ² /g. Alkyne selective hydrogenation catalysts prepared based on these supports show higher activity and selectivity in the selective hydrogenation reaction of carbon distillates and carbon 3 fractions.

Claims (14)

1. A catalyst for selective hydrogenation of alkynes, comprising main active component Pd, optional metal-promoting active component and alumina carrier, wherein, the water absorption rate of the alumina carrier is 40～70%, and the pore volume is 0.6～0.9ml/g, the most probable pore size is 0.100～0.300μm. 2. The catalyst according to claim 1, characterized in that, The metal-promoting active component is selected from at least one of Ag, Bi, Cu, Au, Pb, Zn, and Ga, preferably at least one of Ag, Bi, Zn, and Ga; and/or, In terms of mass percentage, in the catalyst, the Pd content of the main active component is 0.02-0.3%; and/or, In terms of mass percentage, in the catalyst, the content of the metal-promoting active component is 0-0.6%, preferably 0-0.3%. 3. The catalyst according to claim 1, characterized in that, The water absorption rate of the alumina carrier is 50-65%, the pore volume is 0.63-0.8ml/g, and the most probable pore diameter is 0.120-0.250μm; and/or, The specific surface area of the alumina support is 5-120m ² /g, the bulk density is 0.3-0.9g/ml, and the strength is 20-200Nm; preferably, the specific surface area of the alumina support is 20-100m ² /g , the bulk density is 0.5-0.8g/ml, and the strength is 30-100Nm. 4. The catalyst according to claim 1, characterized in that, The alumina carrier also contains 0.01 to 1 wt% of alkali metal elements, alkaline earth metal elements and/or rare earth metal elements; preferably, the alkali metal elements are selected from at least one of Na, K and Li; The alkaline earth metal element is selected from at least one of Mg and Ca; the rare earth metal element is selected from at least one of La, Ce, Pr, and Y. 5. A preparation method of the alkyne selective hydrogenation catalyst described in any one of claims 1 to 4, comprising loading the components comprising the main active component Pd and the metal-promoting active component on The alkyne selective hydrogenation catalyst is obtained on the alumina carrier, preferably, the preparation method specifically includes: impregnating the component containing the alumina carrier in the catalyst containing the Pd compound and the metal-helping compound In the metal compound solution, after drying and roasting, the said alkyne selective hydrogenation catalyst can be obtained. 6. preparation method according to claim 5, is characterized in that, The Pd compound is selected from soluble compounds of metal Pd, preferably selected from at least one of palladium nitrate, palladium chloride, and palladium acetate; and/or, The metal-helping compound is selected from at least one of the chlorides, nitrates, and acetates of Ag, Bi, Cu, Au, Pb, Zn, and Ga, preferably selected from the chlorides of Ag, Bi, Zn, and Ga. , at least one of nitrates; and/or, Based on the saturated water absorption of the alumina support, the amount of the metal compound solution used is 40-90%, preferably 40-70%, of the saturated water absorption of the alumina support. 7. preparation method according to claim 5, is characterized in that, The drying temperature is 40-150°C, and the drying time is 4-48h; preferably, the drying temperature is 50-120°C, and the drying time is 8-24h; and/or, The calcination temperature is 300-500°C; and/or, The calcination time is 2-15 hours, preferably 3-9 hours. 8. The preparation method according to claim 5, characterized in that, the preparation method of the alumina carrier comprises the steps of powder mixing, kneading and molding, drying and roasting, specifically comprising the following steps: Step 1. Mix the components including alumina powder and additives evenly to obtain the powder to be kneaded; Step 2, adding the acidic aqueous solution to the above-mentioned powder to be kneaded for kneading and molding; Step 3. After drying and calcining the kneaded product, the alumina carrier is obtained. 9. preparation method according to claim 8, is characterized in that, The alumina powder includes pseudoboehmite powder, α-Al ₂ O ₃ powder, and optional alumina trihydrate powder and/or fast dealumina powder; and/or, The additive is selected from at least one of silicon-containing compounds and pore forming aids; and/or, The acid in the acidic aqueous solution is selected from at least one of organic acids, inorganic acids, and acid salt compounds, preferably selected from at least one of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, acetic acid, oxalic acid, citric acid, and ammonium dihydrogen phosphate. a; and/or, The mass percent concentration of the acid in the acidic aqueous solution is 0.1-10%, preferably 0.1-5%; and/or, The weight ratio of the acidic aqueous solution to the powder to be kneaded is 0.5-5:1, preferably 0.6-2:1; and/or, A soluble additive is also added to the acidic aqueous solution. Preferably, the soluble additive is at least one selected from alkali metal compounds, alkaline earth metal compounds, and rare earth metal compounds. 10. preparation method according to claim 9, is characterized in that, The pseudo-boehmite powder has a specific surface area of 200-300m ² /g, a pore volume of 0.5-1.2ml/g, and a bulk density of 0.2-0.4g/ml; and/or, In the α-Al ₂ O ₃ powder, the content of α-Al ₂ O ₃ is greater than 95%, the particle size of the powder is 2-100 μm, and the mass content of Na, Fe, and Si is less than 0.1%; and/or, The α-Al ₂ O ₃ powder is 5-30wt% of the total weight of the alumina powder, preferably 5-20wt%; and/or, The mass of the alumina trihydrate powder accounts for 0-10% of the total mass of the alumina powder; and/or, The mass of the fast alumina powder accounts for 0% to 10% of the total mass of the alumina powder; and/or, The silicon-containing compound is selected from water-insoluble silicon-containing compounds, preferably at least one selected from dry silica gel, nano-silicon oxide, and silicon carbide; and/or, In terms of the mass percentage of Si element, the Si element in the silicon-containing compound is 0-1.35% of the total weight of the alumina powder, preferably 0-0.9%; and/or, The forming pore-forming auxiliary agent is selected from at least one of natural organic matter, high molecular polymer, and decomposable basic compound, preferably selected from the group consisting of turnip powder, starch, methylcellulose, and hydroxypropylmethylcellulose Sodium hydroxymethyl cellulose, polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol, polyacrylate acrylic acid, urea, methylamine, At least one of ethylenediamine, ammonium carbonate, ammonium bicarbonate; and/or, The amount of the forming pore-forming aid is 0-20% of the total mass of the alumina carrier, preferably 0-10%; and/or, The acid in the acidic aqueous solution is selected from at least one of nitric acid, acetic acid, oxalic acid, and citric acid; and/or, The alkali metal compound is selected from inorganic salt compounds of metal Na, K, Li, preferably selected from at least one of nitrates and chlorides of metal Na, K, Li; and/or, The alkaline earth metal compound is selected from inorganic salt compounds of metal Mg and Ca, preferably at least one selected from the nitrates and chlorides of metal Mg and Ca; and/or, The rare earth metal compound is selected from soluble rare earth metal salt compounds, preferably at least one selected from nitrates and chlorides of La, Ce, Pr, and Y; and/or, In terms of the mass percentage of metal elements, the metal in the soluble auxiliary agent accounts for 0-1.35% of the total amount of the alumina powder, preferably 0-0.9%. 11. preparation method according to claim 8, is characterized in that, The drying temperature is 60-150°C, and the drying time is 3-48 hours; and/or, The calcination temperature is 800-1200°C, and the calcination time is 3-48 hours; and/or, In the calcination process, when the temperature is below 500°C, the heating rate is 30-150°C/h, and when the temperature is above 500°C, the heating rate is 100-280°C/h. 12. The alkyne selective hydrogenation catalyst according to any one of claims 1 to 4 or the alkyne selective hydrogenation catalyst prepared by the preparation method according to any one of claims 5 to 11, used for alkyne selection hydrogenation reaction. 13. The catalyst according to claim 12, characterized in that, The catalyst is first reduced before use. Preferably, the reduction conditions are: the reduction atmosphere is an atmosphere with a hydrogen content of not less than 50%, the reduction reaction temperature is 80-200°C, and the reduction reaction time is 2-12h . 14. The catalyst according to claim 12, characterized in that, When the catalyst is used for the selective hydrogenation reaction of the carbon distillate, the percentage of acetylene in the carbon distillate is 1.0-5.0%, the reaction temperature is 20-120°C, and the reaction space velocity is 3000-12000h ^-1 ; or, When the catalyst is used for the selective hydrogenation reaction of the C3 fraction, the percentage content of propyne and propadiene in the C3 fraction is 1.0-5.0%, the reaction temperature is 30-70°C, and the reaction space velocity is 20-120h ^{- 1} .