Carbon three-fraction selective hydrogenation catalyst and preparation method thereof
阅读说明：本技术 一种碳三馏分选择加氢催化剂及其制备方法 (Carbon three-fraction selective hydrogenation catalyst and preparation method thereof ) 是由 乐毅 毛祖旺 易水生 彭晖 铁锴 杨晨熹 于 2020-05-20 设计创作，主要内容包括：本发明公开了一种碳三馏分选择性加氢催化剂及其制备方法,所述选择性加氢催化剂包括氧化铝载体和负载于所述氧化铝载体上的主活性组分和任选的助活性组分,在所述氧化铝载体中含有卤素元素,所述卤素元素占所述氧化铝载体总重量的0.01～3wt％,所述主活性组分为钯,所述助活性组分选自元素周期表上IIA族和IB族元素中的至少一种。所述选择性加氢催化剂通过氧化铝载体制备和活性组分负载得到,在氧化铝载体制备时加有含卤素有机物。利用本发明所述方法得到加氢催化剂可以进行加氢反应、尤其是用于碳三液相选择加氢反应,可明显提高催化剂的选择性。(The invention discloses a carbon three-fraction selective hydrogenation catalyst and a preparation method thereof, wherein the selective hydrogenation catalyst comprises an alumina carrier, and a main active component and an optional auxiliary active component which are loaded on the alumina carrier, wherein the alumina carrier contains a halogen element, the halogen element accounts for 0.01-3 wt% of the total weight of the alumina carrier, the main active component is palladium, and the auxiliary active component is at least one of IIA group elements and IB group elements in a periodic table of elements. The selective hydrogenation catalyst is prepared by preparing an alumina carrier and loading active components, and halogen-containing organic matters are added during the preparation of the alumina carrier. The hydrogenation catalyst obtained by the method can be used for hydrogenation reaction, particularly for carbon three-liquid phase selective hydrogenation reaction, and the selectivity of the catalyst can be obviously improved.)
1. A selective hydrogenation catalyst for carbon three-fraction comprises an alumina carrier and a main active component and an optional auxiliary active component which are loaded on the alumina carrier; wherein the content of the first and second substances,
the alumina carrier contains halogen elements, and the halogen elements account for 0.01-3 wt% of the total weight of the alumina carrier;
the main active component is palladium;
the auxiliary active component is selected from at least one of the elements in IIA group and IB group of the periodic table.
2. The carbon three-fraction selective hydrogenation catalyst according to claim 1,
the main active component accounts for 0.01-1.0 wt% of the total weight of the alumina carrier; and/or
The auxiliary active component is selected from at least one of Cu, Ag, Au, Mg, Ca and Sr, preferably at least one of Cu, Ag, Au, Mg and Sr, and more preferably, the auxiliary active component accounts for 0-8 wt% of the total weight of the alumina carrier.
3. The carbon three-fraction selective hydrogenation catalyst according to claim 1,
the specific surface area of the alumina carrier is 10-150 m2(iv) per gram, the bulk density is 0.3-1.0 g/mL, and the pore volume is 0.25-1.00 mL/g; and/or
The alumina carrier contains fluorine and/or chlorine; preferably, the fluorine element accounts for 0.01-1 wt% of the total mass of the carrier, and the chlorine element accounts for 0.01-2 wt% of the total mass of the carrier; and/or
The alumina carrier optionally contains Si element, and the Si element accounts for 0-1.5 wt% of the total weight of the carrier; and/or
The alumina carrier optionally contains at least one of La, Ce, Pr, Li, K and Ba elements, and the mass of at least one of the La, Ce, Pr, Li, K and Ba elements accounts for 0-1.5 wt% of the total mass of the carrier.
4. A method for preparing a carbon three-fraction selective hydrogenation catalyst, preferably for preparing the selective hydrogenation catalyst according to any one of claims 1 to 3, comprising the steps of:
step 1, mixing powder raw materials;
step 2, adding the acidic aqueous solution into the powder for kneading and molding;
step 3, drying and roasting to obtain the alumina carrier;
step 4, synchronously or step-by-step loading the main active component and the optional auxiliary active component on the alumina carrier obtained in the step 3, and drying and roasting to obtain the selective hydrogenation catalyst;
wherein a halogen-containing organic substance, preferably a fluorine-containing and/or chlorine-containing organic substance is added to the powdery raw material and/or the acidic aqueous solution.
5. The method according to claim 4, wherein in step 1, the powdery raw material comprises alumina powder, optionally a Si-containing compound, and optionally a shaped pore former, wherein the alumina powder is selected from pseudo-boehmite powder and optionally other alumina powder; preferably, the other alumina powder is selected from at least one of trihydrate alumina powder, fast deoxidized alumina powder and composite phase alumina powder; more preferably:
the amount of the alumina trihydrate accounts for 0-30 wt% of the total amount of the alumina powder; and/or
The dosage of the fast deoxidized aluminum powder accounts for 0-30 wt% of the total dosage of the aluminum oxide powder; and/or
The amount of the composite phase alumina is 0-30 wt% of the total amount of the alumina powder.
6. The preparation method according to claim 5, wherein the Si-containing compound is a water-insoluble Si-containing compound, preferably selected from but not limited to at least one of dry silica gel, nano-silica, and silicon carbide; preferably, the Si-containing compound is used in an amount of 0 to 1.5 wt% based on the total amount of the alumina powder, wherein the Si-containing compound is used in an amount based on the weight of Si element therein.
7. The preparation method according to claim 5, wherein the forming pore-forming agent is at least one selected from sesbania powder, starch, cellulose, high molecular polymer and decomposable alkaline substances, preferably, the forming pore-forming agent is used in an amount of 0-20 wt% of the total amount of the alumina powder; more preferably:
the cellulose is at least one selected from methylcellulose, hydroxypropyl methylcellulose and sodium hydroxymethyl cellulose; and/or the high molecular polymer is selected from at least one of polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol and polyacrylate acrylic acid; and/or the decomposable alkaline substance is selected from at least one of urea, methylamine, ethylenediamine, ammonium carbonate and ammonium bicarbonate.
8. The production method according to claim 4, wherein, in step 2,
the acidic aqueous solution is selected from at least one of hydrochloric acid aqueous solution, nitric acid aqueous solution, sulfuric acid aqueous solution, acetic acid aqueous solution, oxalic acid aqueous solution, citric acid aqueous solution, phosphoric acid aqueous solution and ammonium dihydrogen phosphate aqueous solution, and preferably from at least one of nitric acid aqueous solution, acetic acid aqueous solution, oxalic acid aqueous solution and citric acid aqueous solution; and/or
The weight ratio of the acidic aqueous solution to the powdery raw material is (0.5-5): 1, preferably (0.6-2): 1; and/or
Adding a soluble auxiliary agent into the acidic aqueous solution, wherein the soluble auxiliary agent is selected from at least one inorganic substance of La, Ce, Pr, Li, K and Ba, preferably, the soluble auxiliary agent is selected from at least one nitric compound and/or oxide of La, Ce, Pr, Li, K and Ba, more preferably, the amount of the soluble auxiliary agent is 0-1.5 wt% of the total amount of the alumina powder, and the amount of the soluble auxiliary agent is calculated by the weight of La, Ce, Pr, Li, K or Ba.
9. The production method according to claim 4, wherein, in step 3,
the drying temperature is 60-150 ℃, and preferably 80-150 ℃; the drying time is 3-48 hours, preferably 5-25 hours; and/or
The roasting temperature is 800-1200 ℃, and preferably 900-1200 ℃; the roasting time is 3-48 hours, preferably 5-24 hours.
10. The production method according to claim 4, wherein, in step 4,
synchronously or step-by-step spraying a solution I containing a main active component and an optional solution II containing an auxiliary active component on the alumina carrier obtained in the step 3; and/or
The drying is carried out for 2-10 h at 60-160 ℃, preferably for 4-8 h at 80-120 ℃; and/or
The roasting is carried out for 2-10 h at 300-600 ℃, and for 4-8 h at 400-500 ℃.
11. The production method according to claim 4,
the dosage of the fluorine-containing organic matter is 0.01-1 wt%, preferably 0.01-0.7 wt% of the total dosage of the powdery raw materials, wherein the dosage of the fluorine-containing organic matter is calculated by the weight of fluorine element in the fluorine-containing organic matter; and/or
The dosage of the chlorine-containing organic matter is 0.01-2 wt%, preferably 0.01-1 wt% of the total dosage of the powdery raw materials, wherein the dosage of the chlorine-containing organic matter is based on the weight of chlorine element in the powdery raw materials.
12. The method according to any one of claims 4 to 11, wherein the fluorine-containing and/or chlorine-containing organic substance is at least one selected from a fluorine-containing and/or chlorine-containing polymer, a suspension of a fluorine-containing and/or chlorine-containing polymer, and a fluorine-containing and/or chlorine-containing organic compound.
13. The production method according to claim 12,
the fluorine-containing and/or chlorine-containing polymer is selected from one or more of polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene/ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, chlorotrifluoroethylene/ethylene copolymer, polyvinyl chloride, polyvinylidene chloride, chlorinated polypropylene, chlorinated polyethylene and vinyl chloride/vinylidene chloride copolymer; preferably, the fluorine-and/or chlorine-containing polymer has a particle diameter of less than 100 μm, preferably less than 50 μm; and/or
The suspension of fluorine-containing and/or chlorine-containing polymer is selected from polytetrafluoroethylene suspensions; and/or
The fluorine-containing and/or chlorine-containing organic compound is a water-soluble organic compound containing fluorine and/or chlorine elements, and preferably, the fluorine-containing and/or chlorine-containing organic compound is selected from at least one of tetrafluoropropanol, trifluoroethanol, trifluoroacetal, chloroacetic acid, dichloroacetic acid, trichloroacetic acid and trichloroethanol.
14. A selective hydrogenation catalyst for carbon three-cut fraction obtained by the preparation method of any one of claims 4 to 13.
Technical Field
The invention belongs to the field of hydrogenation catalysts, and particularly relates to a selective hydrogenation catalyst and a preparation method thereof.
Background
In the propylene production process, the carbon-three fraction usually contains 2 to 5 percent of propyne (MA) and Propadiene (PD), and the two compounds are poisons of a polypropylene catalyst, so that propylene is not polymerized or the consumption of the catalyst is increased, and the performance of the polymerized product is reduced, therefore, MAPD of the carbon-three fraction needs to be removed in the propylene production process. The method for removing MAPD in carbon three-fraction is catalytic selective hydrogenation.
Chinese patent CN1958155A discloses a method for coating Al on an inert carrier2O3The coating is an alkyne and dialkene selective hydrogenation catalyst using Pd, Ag, Bi and alkali metals as metal active components, and the catalyst prepared by the method can reduce the dosage of a main catalyst Pd, a cocatalyst Ag and the like. Chinese patent CN1279126A discloses the use of diatomite and SiO2、TiO2、Al2O3The catalyst formed by loading metal components such as Pd, Bi and the like enables olefins to have high selectivity and high hydrogenation activity in hydrogenation reaction, and simultaneously reduces the generation amount of green oil, prolongs the service life of the catalyst and reduces the production cost. Chinese patent CN1277987A discloses a selective hydrogenation process by catalytic distillation of carbon three-fraction, using Pd or other metals as active component, the metals are distributed on the surface of the carrier in an eggshell shape. The catalyst carrier is prepared by molding, drying and roasting powdery aluminum hydroxide serving as a raw material, and can be processed into honeycombs, wheel shapes, annular shapes and the like. The catalyst of the process has dual functions of catalysis and fractionation, the reaction efficiency is high, and the service cycle of the catalyst is long. Furthermore, U.S. Pat. No. 4, 4,533,779 describes Pd/Al2O3In which Au element is addedIs used as a catalyst promoter, and ammonia water is used for washing off chlorine element in the catalyst so as to improve the sulfur resistance of the catalyst. US patent US 5,364,998 teaches to Pd/Al2O3The selectivity of the catalyst can be improved by adding elements such as Ga and In.
Disclosure of Invention
In order to overcome the problems in the prior art, the invention can obviously improve the selectivity of the catalyst by loading the active component on the alumina carrier added with F and/or Cl.
One purpose of the invention is to provide a carbon three-fraction selective hydrogenation catalyst, which comprises an alumina carrier, a main active component and an optional auxiliary active component, wherein the main active component and the optional auxiliary active component are loaded on the alumina carrier; the alumina carrier contains halogen elements, and the halogen elements account for 0.01-3 wt% of the total weight of the alumina carrier; the main active component is palladium, and the auxiliary active component is at least one of IIA group elements and IB group elements in the periodic table of elements.
In a preferred embodiment, the main active component accounts for 0.01-1.0 wt%, preferably 0.02-0.5 wt% of the total weight of the alumina carrier.
In a preferred embodiment, the co-active component is selected from at least one of Cu, Ag, Au, Mg, Ca and Sr.
In a further preferred embodiment, the co-active component is selected from at least one of Cu, Ag, Au, Mg and Sr.
In a further preferred embodiment, the co-active component is present in an amount of 0 to 8 wt%, preferably 0 to 5 wt%, based on the total weight of the alumina support.
In a preferred embodiment, the alumina has a specific surface area of 10 to 150m2(iv) a bulk density of 0.3 to 1.0g/mL and a pore volume of 0.25 to 1.00 mL/g.
In a more preferred embodiment, the alumina support has a specific surface area of 20 to 100m2(iv) per gram, bulk density of 0.4 to 0.9g/mL, pore volume of 0.35 to 1.00 mL/g.
In a preferred embodiment, the halogen element is fluorine and/or chlorine.
In a further preferred embodiment, the fluorine element accounts for 0.01 to 1 wt% of the total mass of the carrier, and the chlorine element accounts for 0.01 to 2 wt% of the total mass of the carrier.
In a further preferred embodiment, the fluorine element accounts for 0.01 to 0.7 wt% of the total mass of the carrier, and the chlorine element accounts for 0.01 to 1.0 wt% of the total mass of the carrier.
In a preferred embodiment, the alumina support optionally contains Si element.
In a further preferred embodiment, the Si element accounts for 0 to 1.5 wt%, preferably 0 to 1 wt%, and more preferably 0 to 0.5 wt% of the total weight of the carrier.
In a preferred embodiment, at least one of La, Ce, Pr, Li, K, and Ba elements is optionally contained in the alumina carrier, and the mass of at least one of La, Ce, Pr, Li, K, and Ba elements accounts for 0 to 1.5 wt%, preferably 0 to 1 wt%, of the total mass of the carrier.
Wherein, the elements such as La, Ce, Pr, Li, K, Ba and the like can further adjust parameters such as surface acidity, strength, specific surface area, pore volume and the like of the carrier.
The second purpose of the invention is to provide a preparation method of the carbon three-fraction selective hydrogenation catalyst, which comprises the following steps:
step 1, mixing powder raw materials;
step 2, adding the acidic aqueous solution into the powder for kneading and molding;
step 3, drying and roasting to obtain an alumina carrier;
step 4, synchronously or step-by-step loading the main active component and the optional auxiliary active component on the alumina carrier obtained in the step 3, and drying and roasting to obtain the selective hydrogenation catalyst;
wherein, halogen-containing organic substances, preferably fluorine-containing and/or chlorine-containing organic substances, are added to the powdery raw material in the step 1 and/or the acidic aqueous solution in the step 2.
In a preferred embodiment, the amount of the fluorine-containing organic substance is 0.01 to 1 wt%, preferably 0.01 to 0.7 wt% of the total amount of the powdery raw materials, wherein the amount of the fluorine-containing organic substance is based on the weight of fluorine element therein.
In a further preferred embodiment, the amount of the chlorine-containing organic compound is 0.01 to 2 wt%, preferably 0.01 to 1.0 wt% of the total amount of the powdery raw materials, wherein the amount of the chlorine-containing organic compound is based on the weight of chlorine element therein.
In a preferred embodiment, the fluorine-containing and/or chlorine-containing organic substance is selected from at least one of a fluorine-containing and/or chlorine-containing polymer powder, a fluorine-containing and/or chlorine-containing polymer suspension, and a fluorine-containing and/or chlorine-containing organic compound.
In a further preferred embodiment, when the fluorine-containing and/or chlorine-containing organic substance is a fluorine-containing and/or chlorine-containing polymer powder, it is added to the powdery raw material; when the fluorine-containing and/or chlorine-containing organic matter is a fluorine-containing and/or chlorine-containing polymer suspension, adding the fluorine-containing and/or chlorine-containing organic matter into the acidic aqueous solution; when the fluorine-containing and/or chlorine-containing organic compound is a fluorine-containing and/or chlorine-containing organic compound, adding the fluorine-containing and/or chlorine-containing organic compound into the acidic aqueous solution.
The preparation method is remarkably characterized in that organic matters containing halogen, particularly polymers containing halogen or polymer suspension liquid are added in the preparation process, so that the pore structure of the alumina carrier can be effectively adjusted. (1) Under the condition of high temperature, a large number of micropores can be formed by the gasification and decomposition of hydrocarbon in the organic matters containing halogen during roasting, the pore structure of the alumina carrier is increased, part of fluorine and chlorine can form gas-phase compounds to diffuse and separate from the carrier, and part of the gas-phase compounds tightly combined with the alumina can be retained on the carrier for decomposition; (2) the halogen enters the alumina framework, and alumina microcrystal is more easily converted into a flaky shape during high-temperature roasting, so that the pore structure of the alumina is influenced, the pore volume is generally promoted to be increased, the specific surface area is increased, and the bulk density is reduced; (3) in addition, halogen can exist in a doped form in the carrier, the surface acidity of the prepared alumina carrier can be influenced by the property of strong electronegativity, and the halogen (particularly fluorine atoms and chlorine atoms) on the alumina carrier can pull electrons on aluminum atoms to attract electrons of hydroxyl groups around the aluminum atoms, so that the hydroxyl groupsThe hydrogen protons on the carrier are easier to ionize, and the halogen can also cause the crystal structure of the carrier to be distorted to cause partial Al-OH polarization, which can promote the surface of the carrierAnd (4) forming acid sites.
Compared with the method that organic matters are respectively added to increase the pore volume and the specific surface area of the alumina carrier, inorganic matters added with fluorine and chlorine change the pore structure of the alumina, and the organic matters added with fluorine and/or chlorine can simultaneously act with fluorine and/or chlorine elements in the high-temperature roasting process of the alumina, so that the alumina carrier with better comprehensive performance is prepared, the addition times of the auxiliary agents are reduced, and the forming method is simplified.
In a preferred embodiment, the fluorine-containing and/or chlorine-containing polymer is selected from one or more of, but not limited to, polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene/ethylene copolymer, polyvinylidene fluoride, polyvinyl fluoride, polychlorotrifluoroethylene, chlorotrifluoroethylene/ethylene copolymer, polyvinyl chloride, polyvinylidene chloride, chlorinated polypropylene, chlorinated polyethylene, vinyl chloride/vinylidene chloride copolymer.
In a further preferred embodiment, the fluorine-and/or chlorine-containing polymer is selected from one or more of polytetrafluoroethylene, tetrafluoroethylene/hexafluoropropylene copolymer, tetrafluoroethylene/ethylene copolymer, polyvinylidene fluoride, polyvinyl chloride, chlorinated polypropylene, chlorinated polyethylene.
In a further preferred embodiment, the fluorine-and/or chlorine-containing polymer has a particle diameter of less than 100. mu.m, preferably less than 50 μm, which facilitates uniform mixing with the alumina powder.
In a preferred embodiment, the fluorine-and/or chlorine-containing polymer suspension is selected from, but not limited to, polytetrafluoroethylene suspensions.
In a further preferred embodiment, the weight concentration of the fluorine-and/or chlorine-containing polymer suspension is from 20% by weight to 90% by weight, preferably from 40% by weight to 70% by weight.
In a preferred embodiment, the fluorine-and/or chlorine-containing organic compound is a water-soluble organic compound containing fluorine and/or chlorine elements.
In a further preferred embodiment, the fluorine-and/or chlorine-containing organic compound is selected from, but not limited to, at least one of tetrafluoropropanol, trifluoroethanol, trifluoroacetaldehyde, chloroacetic acid, dichloroacetic acid, trichloroacetic acid and trichloroethanol.
In a still further preferred embodiment, the fluorine-and/or chlorine-containing organic compound is selected from at least one of tetrafluoropropanol, trifluoroethanol, chloroacetic acid, trichloroacetic acid and trichloroethanol.
In a preferred embodiment, in step 1, the powdered raw material comprises alumina powder, optionally a Si-containing compound, and optionally a shaped pore former, wherein the alumina powder is selected from pseudo-boehmite powder and optionally other alumina powder.
In a further preferred embodiment, the mass content of Na and Fe in the pseudo-boehmite powder is less than 0.1%, the mass reduction after high-temperature roasting is not higher than 40%, and the particle size of the powder is less than 200 μm.
In a still further preferred embodiment, the other alumina powder is selected from at least one of alumina powder trihydrate, fast deoxidized alumina powder, and composite phase alumina powder.
In a preferred embodiment, the alumina trihydrate is selected from at least one of gibbsite, bayerite, and nordstrandite.
In a further preferred embodiment, the alumina trihydrate is used in an amount of 0 to 30 wt%, preferably 0 to 20 wt%, based on the total amount of alumina powder.
In a preferred embodiment, the fast deoxidized aluminum powder is obtained by fast dehydration of aluminum hydroxide, wherein the weight content of Na and Fe is less than 0.1 wt%.
In a further preferred embodiment, the amount of the fast deoxidized aluminum powder is 0 to 30 wt%, preferably 0 to 20 wt%, of the total amount of the aluminum oxide powder.
In a preferred embodiment, the composite phase alumina is obtained by high temperature calcination of an aluminum hydroxide selected from the group consisting of alumina trihydrate or alumina monohydrate (e.g., gibbsite, bayerite, boehmite, etc.).
In a further preferred embodiment, the amount of the composite phase alumina is 0 to 30 wt%, preferably 0 to 20 wt%, based on the total amount of the alumina powder.
In a preferred embodiment, the Si-containing compound is a water-insoluble Si-containing compound, preferably selected from at least one of, but not limited to, dry silica gel, nano-silica, silicon carbide.
In a further preferred embodiment, the nano silica and dry silica gel have an average particle size of less than 120 nm.
In a further preferred embodiment, the amount of the Si-containing compound is 0 to 1.5 wt%, preferably 0 to 1 wt%, and more preferably 0 to 0.5 wt% of the total amount of the alumina powder, wherein the amount of the Si-containing compound is based on the weight of Si element therein.
In a preferred embodiment, the pore-forming agent is at least one selected from sesbania powder, starch, cellulose, high molecular organic polymer and decomposable alkaline substance.
In a further preferred embodiment, the cellulose is selected from at least one of methylcellulose, hydroxypropylmethylcellulose, sodium hydroxymethylcellulose; the high molecular polymer is selected from at least one of polyethylene microspheres, polystyrene, polyethylene oxide, polyethylene glycol, polyvinyl alcohol, sodium polyacrylate, polyethylene glycol and polyacrylate acrylic acid; the decomposable alkaline substance is at least one selected from urea, methylamine, ethylenediamine, ammonium carbonate and ammonium bicarbonate.
In a further preferred embodiment, the amount of the formed pore-forming agent is 0 to 20 wt%, preferably 0 to 10 wt%, of the total amount of the alumina powder.
In step 1, the powder mixing may be performed in a dedicated mixer, or the powder may be added to a kneader and then dry-mixed without adding a solution for a certain time. The time required for mixing can be determined empirically by one skilled in the art. Powder mixing is an important step for preparing a carrier, and the uniform mixing of the powder can be ensured by optimizing the structure of a mixer, prolonging the mixing time and the like.
In a preferred embodiment, in step 2, the acidic aqueous solution is at least one selected from the group consisting of an aqueous hydrochloric acid solution, an aqueous nitric acid solution, an aqueous sulfuric acid solution, an aqueous acetic acid solution, an aqueous oxalic acid solution, an aqueous citric acid solution, an aqueous phosphoric acid solution and an aqueous ammonium dihydrogen phosphate solution, and is preferably at least one selected from the group consisting of an aqueous nitric acid solution, an aqueous acetic acid solution, an aqueous oxalic acid solution and an aqueous citric acid solution.
In a further preferred embodiment, the concentration of the acidic aqueous solution is 0.5 to 10 wt%, preferably 0.5 to 5 wt%.
In a further preferred embodiment, in step 2, the weight ratio of the acidic aqueous solution to the powdery raw material is (0.5 to 5):1, preferably (0.6 to 2): 1.
The amount of the acid in the acidic aqueous solution can be adjusted by those skilled in the art according to the plasticity of the kneaded blank and the specific surface area, strength, bulk density and other data of the carrier after high-temperature roasting.
In a preferred embodiment, in step 2, a soluble auxiliary selected from at least one inorganic substance of La, Ce, Pr, Li, K and Ba is added to the acidic aqueous solution.
In a further preferred embodiment, the soluble auxiliary agent is selected from at least one nitrate compound and/or oxide of La, Ce, Pr, Li, K and Ba.
In a further preferred embodiment, the amount of the soluble assistant is 0 to 1.5 wt%, preferably 0 to 1 wt%, based on the total amount of the alumina powder, wherein the amount of the soluble assistant is calculated by the weight of La, Ce, Pr, Li, K or Ba.
In the step 2, the kneading molding is to add the acidic aqueous solution into the uniformly mixed powder, mix and knead continuously, react part of the alumina powder with acid to form a plastic blank, and extrude and mold the blank into a required shape and size. The time for kneading and molding, the pressure for extrusion molding, and the like are related to the size of the equipment used, the composition of the alumina powder, the composition of the acid solution, and the like, and can be determined empirically by those skilled in the art.
In a preferred embodiment, in step 3, the drying temperature is 60 to 150 ℃, and the drying time is 3 to 48 hours.
In a further preferred embodiment, in the step 3, the drying temperature is 80 to 150 ℃, and the drying time is 5 to 25 hours.
In a preferred embodiment, in the step 3, the roasting temperature is 800-1200 ℃, and the roasting time is 3-48 hours.
In a further preferred embodiment, in the step 3, the roasting temperature is 900 to 1200 ℃, and the roasting time is 4 to 10 hours.
In a more preferred embodiment, the heating rate is 30 to 150 ℃/hr when the firing is performed at 600 ℃ or lower, and the heating rate is 280 ℃/hr when the firing is performed at 600 ℃ or higher.
Wherein, the drying and roasting step is to dry, knead and shape the moisture in the green body, the solid phase reaction occurs in the high temperature roasting process, and the alumina particles are bonded together to form the alumina carrier with certain strength.
In a preferred embodiment, in step 4, the primary active component-containing solution I and the optional co-active component-containing solution II are sprayed simultaneously or in steps onto the alumina support obtained in step 3.
In a preferred embodiment, in step 4, the main active component is palladium, preferably, it accounts for 0.01-1.0 wt% of the total weight of the alumina carrier.
In a preferred embodiment, in step 4, the co-active component is selected from at least one of the group IIA and IB elements of the periodic table of the elements, preferably at least one from Cu, Ag, Au, Mg, Ca and Sr, more preferably at least one from Cu, Ag, Au, Mg and Sr.
In a further preferred embodiment, in step 4, the co-active component accounts for 0 to 8 wt%, preferably 0 to 5 wt%, of the total weight of the alumina support.
In a preferred embodiment, in step 4, the drying is performed at 60 to 160 ℃ for 2 to 10 hours.
In a further preferred embodiment, in the step 4, the drying is performed at 80 to 120 ℃ for 4 to 8 hours.
In a preferred embodiment, the baking is performed at 300 to 600 ℃ for 2 to 10 hours.
In a further preferred embodiment, the calcination is carried out at 400 to 500 ℃ for 4 to 8 hours.
The third purpose of the invention is to provide a carbon three-fraction hydrogenation catalyst obtained by the preparation method of the second purpose of the invention, and the specific surface area of the catalyst is 10-150 m2(iv) per gram, bulk density of 0.3 to 0.9g/mL, pore volume of 0.25 to 1.00 mL/g.
Compared with the prior art, the invention has the following beneficial effects:
(1) the alumina carrier adopted by the invention is added with halogen-containing organic matters during preparation, and in the high-temperature roasting process, the organic matters and the halogen can act simultaneously, so that the alumina carrier is endowed with special properties, such as high specific surface area, high pore volume, low bulk density and the like;
(2) the hydrogenation catalyst is used for hydrogenation reaction, especially for carbon three-liquid phase selective hydrogenation reaction, and the selectivity of the catalyst can be obviously improved.
Detailed Description
While the present invention will be described in detail with reference to the following examples, it should be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the present invention.
The raw materials used in the examples and comparative examples are disclosed in the prior art if not particularly limited, and may be, for example, directly purchased or prepared according to the preparation methods disclosed in the prior art.
[ example 1 ]
1.00g of concentrated nitric acid, 3.00g of oxalic acid and 1.25g of trifluoroethanol are weighed and added into 210g of deionized water to prepare a mixed solution. Weighing 180g of pseudo-boehmite powder, 20g of fast deoxidized aluminum powder, 6g of sesbania powder, 5g of starch and 3g of crosslinked polyethylene microspheres with the particle size of about 40 mu m, uniformly mixing in a mixer, and transferring into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 120 deg.C for more than 12hr, baking at 1180 deg.C for 6hr, controlling heating rate at 600 deg.C or below 80 deg.C/hr and at 600 deg.C or above 200 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier S1 with fluorine loading of about 0.5%.
PdCl with a concentration of 25mgPd/mL is measured2The solution was diluted to 12mL with deionized water to 50mL, adjusted to pH 3.5 with 1mol/L NaOH solution, and then diluted to 65 mL. Weighing the Al2O3100g of the support, onto which the PdCl thus prepared was sprayed2And (3) solution. The sample was dried at 120 ℃ for 6h and decomposed at 450 ℃ for 6h by passing air through a tube furnace to give catalyst A1 having a Pd content of 0.3 wt%.
[ example 2 ]
2.00g of concentrated nitric acid and 1.75g of cerous nitrate hexahydrate are weighed and added into 190g of deionized water to prepare a mixed solution. 200g of pseudo-boehmite powder, 8g of sesbania powder, 10g of starch and 0.48g of polyvinylidene fluoride powder are weighed, mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 120 deg.C for more than 12hr, calcining at 1170 deg.C for 6hr, controlling heating rate at 600 deg.C or below 100 deg.C/hr and at 600 deg.C or above 230 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier S2 with fluorine loading of about 0.2% and Ce loading of about 0.4%.
Pd (NO) was measured at a concentration of 25mgPd/mL3)212mL of the solution was added 20mgAg/mL of AgNO35mL of the solution was diluted to 65mL with deionized water. Weighing the Al2O3100g of the carrier, onto which the prepared solution was sprayed. Samples were taken at 120 deg.CDrying for 6h, and then introducing air into a tube furnace to decompose for 6h at 450 ℃ to obtain the catalyst A2, wherein the Pd content is 0.3 wt% and the Ag content is 0.1 wt%.
[ example 3 ]
1.00g of concentrated nitric acid, 4.00g of acetic acid and 0.15g of 60% polytetrafluoroethylene concentrated dispersion are weighed and added into 190g of deionized water to prepare a mixed solution. 200g of pseudo-boehmite powder, 6g of sesbania powder and 6g of starch are weighed, mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 120 deg.C for more than 12hr, calcining at 1170 deg.C for 6hr, controlling heating rate at 600 deg.C or below 100 deg.C/hr and at 600 deg.C or above 200 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier S3 with fluorine loading of about 0.05%.
PdCl with a concentration of 25mgPd/mL is measured2The solution was diluted to 12mL with deionized water to 50mL, adjusted to pH 3.5 with 1mol/L NaOH solution, and then diluted to 65 mL. Weighing the Al2O3100g of the carrier, to which the prepared solution was sprayed. The sample was dried at 120 ℃ for 6h and decomposed at 450 ℃ for 6h by passing air through a tube furnace to give catalyst A3 having a Pd content of 0.3 wt%.
[ example 4 ]
Pd (NO) was measured at a concentration of 25mgPd/mL3)212mL of the solution, 1.575g of AgNO was added3Diluted to 65mL with deionized water. Al prepared as in example 3 was weighed2O3100g of the carrier, to which the prepared solution was sprayed. The sample was dried at 120 ℃ for 6h and then decomposed at 450 ℃ for 6h by passing air through a tube furnace to obtain catalyst A4 having a Pd content of 0.3 wt% and an Ag content of 0.1 wt%.
[ example 5 ]
2.00g of concentrated nitric acid, 2.00g of acetic acid, 0.30g of 60% polytetrafluoroethylene concentrated dispersion and 3.03g of lanthanum nitrate hexahydrate are weighed and added into 180g of deionized water to prepare a mixed solution. 190g of pseudo-boehmite powder, 10g of alumina trihydrate, 8g of sesbania powder, 2g of hydroxymethyl cellulose, 3g of ammonium carbonate and 0.3g of nano silicon oxide with the average particle size of 75nm are weighed, mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 140 deg.C for more than 9hr, baking at 1190 deg.C for 6hr, controlling heating rate at 600 deg.C or below 100 deg.C/hr and at 600 deg.C or above 150 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier S4 with fluorine loading of about 0.1%, La loading of about 0.7%, and Si loading of about 0.1%.
PdCl with a concentration of 25mgPd/mL is measured2The solution was diluted to 12mL with deionized water to 50mL, adjusted to pH 3.5 with 1mol/L NaOH solution, and then diluted to 62 mL. Weighing the Al2O3100g of the support, onto which the PdCl thus prepared was sprayed2And (3) solution. The sample was dried at 120 ℃ for 6h and decomposed at 450 ℃ for 6h by passing air through a tube furnace to give catalyst A5 having a Pd content of 0.3 wt%.
[ example 6 ]
3.00g of concentrated nitric acid and 0.73g of potassium nitrate were weighed and added to 200g of deionized water to prepare a mixed solution. 200g of pseudo-boehmite powder, 6g of sesbania powder, 6g of starch and 1.04g of K-value 72-71 polyvinyl chloride powder are weighed, mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 120 deg.C for more than 12hr, baking at 1195 deg.C for 6hr, controlling heating rate at 600 deg.C or below 100 deg.C/hr and at 600 deg.C or above 200 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier S6 with chlorine loading of about 0.4% and K loading of about 0.2%.
PdCl with a concentration of 25mgPd/mL is measured28mL of the solution was diluted to 50mL with deionized water, the pH was adjusted to 3.5 with 1mol/L NaOH solution, and the solution was diluted to 57 mL. Weighing the Al2O3100g of the support, onto which the PdCl thus prepared was sprayed2And (3) solution. The sample was dried at 120 ℃ for 6h and decomposed at 450 ℃ for 6h by passing air through a tube furnace to give catalyst A6 having a Pd content of 0.2 wt%.
[ example 7 ]
2.00g of concentrated nitric acid, 2.00g of oxalic acid, 1.49g of tetrafluoropropanol and 0.81g of barium nitrate were weighed and added to 230g of deionized water to prepare a mixed solution. 160g of pseudo-boehmite powder, 40g of fast deoxidized aluminum powder, 8g of methyl cellulose, 7g of polyvinyl alcohol and 5g of ethylenediamine are weighed and mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 80 deg.C for more than 25hr, calcining at 1020 deg.C for 10hr, controlling heating rate at 600 deg.C or below 50 deg.C/hr and at 600 deg.C or above 150 deg.C/hr, and naturally cooling to room temperature to obtain the alumina carrier S7.
Pd (NO) was measured at a concentration of 25mgPd/mL3)212mL of solution was diluted to 65mL with deionized water. Weighing the Al2O3100g of the carrier, onto which the prepared solution was sprayed. Drying the sample at 110 ℃ for 8h, introducing air into a tube furnace, and decomposing at 400 ℃ for 8h to obtain a catalyst semi-finished product.
20mgAu/mL of AuCl was measured33mL of solution, diluted to 65mL with deionized water, and the secondary solution was sprayed onto the semi-finished product. The sample was dried at 110 ℃ for 8h and decomposed at 400 ℃ for 8h in a tube furnace with air to give catalyst A7 having a Pd content of 0.3 wt% and an Au content of 0.06 wt%.
[ example 8 ]
1.00g of concentrated nitric acid, 3.00g of oxalic acid and 0.46g of chloroacetic acid are weighed and added into 210g of deionized water to prepare a mixed solution. Baking bayerite at 900 ℃ for 10 hours to obtain composite phase alumina of theta-alumina and alpha-alumina, weighing 40g of composite phase alumina, 160g of pseudo-boehmite powder, 6g of hydroxypropyl methyl cellulose, 5g of polyethylene oxide and 3g of urea, uniformly mixing in a mixer, and transferring into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 150 deg.C for more than 5hr, baking at 1180 deg.C for 4hr, controlling heating rate at 600 deg.C or below at 120 deg.C/hr and at 600 deg.C or above at 250 deg.C/hr, and naturally cooling to room temperature to obtain the alumina carrier S8.
Pd (NO) was measured at a concentration of 25mgPd/mL3)24mL of solution was diluted to 62mL with deionized water. Weighing the Al2O3100g of the carrier, onto which the prepared solution was sprayed. The sample is dried at 100 ℃ for 4h, and then is decomposed at 500 ℃ for 4h by introducing air into a tube furnace to obtain a catalyst semi-finished product.
Weighing Cu (NO)3)2·3H2Dissolving O19 g in 100ml of deionized water, and adding the deionized water until the solution amount is 124 ml; taking the above Al2O3100g of carrier, onto which Cu (NO) formulated was sprayed3)262ml of the solution. Drying the sample at 100 ℃ for 4h, introducing air into a tube furnace, and decomposing at 400 ℃ for 4h to obtain an intermediate in the second step; the remaining 62ml of Cu (NO) was added3)2The solution was sprayed onto the second step intermediate and the sample dried at 100 ℃ for 4h and then decomposed in a tube furnace with air at 400 ℃ for 4h to give catalyst A8 having a Pd content of 0.10 wt% and a Cu content of 5.0 wt%.
Comparative example 1
3.00g of concentrated nitric acid is weighed and added into 190g of deionized water to prepare a mixed solution. 200g of pseudo-boehmite powder, 8g of sesbania powder and 4g of starch are weighed, mixed uniformly in a mixer and transferred into a kneader. Slowly adding the mixed solution, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Oven drying at 120 deg.C for more than 12hr, calcining at 1195 deg.C for 6hr, controlling heating rate at 300 deg.C/hr, and naturally cooling to room temperature to obtain alumina carrier D1.
PdCl with a concentration of 25mgPd/mL is measured2The solution was diluted to 12mL with deionized water to 30mL, adjusted to pH 3.5 with 1mol/L NaOH solution, and diluted to 45 mL. Weighing the Al2O3100g of the support, onto which the PdCl thus prepared was sprayed2And (3) solution. The sample was dried at 120 ℃ for 6h and decomposed at 450 ℃ for 6h by passing air through a tube furnace to give catalyst B1 having a Pd content of 0.3 wt%.
Comparative example 2
The catalyst was a BC-L-83 catalyst for industrial use, identified as B2 in the following table, and had a Pd content of 0.3 wt%.
Comparative example 3
The procedure of example 2 was repeated except that: when the alumina carrier is prepared, 0.48g of polyvinylidene fluoride powder is not used, and the active component loading process is the same under the same conditions, so that the catalyst B3 is obtained.
Comparative example 4
The procedure of example 1 was repeated except that: catalyst B4 was obtained by using 2.19g of potassium fluoride in place of 1.25g of trifluoroethanol (both having the same fluorine content) and carrying the active component under the same conditions.
Comparative example 5
The procedure of example 1 was repeated except that (1.427g of ammonium fluoride and 1.7g of ethyl acetate) was used in place of 1.25g of trifluoroethanol (both having the same fluorine content), and the same conditions were used for the same procedures for supporting the active component, to obtain catalyst B5.
Comparative example 6
The procedure of example 1 was repeated except that 1.427g of ammonium fluoride was used instead of 1.25g of trifluoroethanol (both having the same fluorine content), and the same procedure was carried out under the same conditions as in the case of the loading of the active component, to obtain an alumina carrier B6.
[ Experimental example 1 ]
Pyridine adsorption infrared detection was performed on the catalysts obtained in example 2(A1) and comparative examples 3 to 4 (B3/B4, respectively). Wherein, fluorine-containing organic matter is added in the preparation process of A1, fluorine-containing matter is not added in the preparation process of B3, and fluorine-containing inorganic matter is added in the preparation process of B4.
The pyridine adsorption infrared spectrum of the example 2 contains 1448cm-1、1610cm-1、1540cm-1And 1645cm-1Wherein, at 1448cm-1，1610cm-1The nearby position corresponds to pyridine adsorbed to L acid site, 1540cm-1And 1645cm-1The nearby position corresponds to the pyridine adsorbed on the acid B site;
only L acid sites (1448 cm) were present in the pyridine adsorption IR spectrum of comparative example 3-1，1610cm-1)；
In the pyridine adsorption infrared spectrum of comparative example 4, the contentHas 1448cm-1、1610cm-1、1540cm-1And 1645cm-1But, its B acid site (1540 cm)-1And 1645cm-1) The absorption peak intensity of (A) is obviously less than that of A1 prepared by adding fluorine-containing organic matter, which indicates that B acid sites contained in B4 are obviously less than that of A1.
[ Experimental example 3 ]
The alumina supports prepared in the above examples and comparative examples were measured for specific surface area, bulk density and pore volume. Wherein the specific surface area is measured by adopting a nitrogen physical adsorption BET method; the bulk density is obtained by measuring the mass of 100mL of alumina carrier, and an average value is taken after each sample is measured for 3 times; the pore volume is measured by a mercury intrusion method, and is carried out by referring to a common alumina carrier pore volume measuring method. The results of the measurements are shown in Table 1 below.
Table 1:
as can be seen from Table 1, compared with the comparative example, the alumina carrier prepared by the method of the invention has higher specific surface area and pore volume, which is beneficial to preparing the supported metal catalyst; meanwhile, the bulk density is reduced, and the using amount of the catalyst prepared by using the alumina carrier can be reduced under the condition of the same filling volume, so that the market competitiveness of the prepared catalyst is favorably improved.
[ Experimental example 2 ]
The catalysts of the examples and comparative examples were subjected to a selective hydrogenation test of propyne and propadiene in a three-carbon cut under the following reaction conditions:
92mL of the catalyst was charged into a stainless steel tube reactor, and after replacement with nitrogen, hydrogen was added to the reaction mixture and the mixture was introduced into the reactor. The composition (mole fraction) of the reaction raw material was 8.93% propane, 89.2% propylene, 0.85% allene, 1.02% propyne, and the content ratio of hydrogen to alkyneAbout 1.4-1.6, liquid space velocity of 70h-1。
The catalysts of the examples and comparative examples were used to evaluate the selective hydrogenation performance of propyne and propadiene, and the conversion of propyne and propadiene to propylene after 8 hours and the corresponding selectivities of each catalyst are shown in table 2. The Conversion (Conversion) and Selectivity (Selectivity) of propyne and propadiene (MAPD in the table) were calculated as follows:
the experimental result shows that the selectivity of the catalyst prepared by the method of the invention for the hydrogenation reaction of the propine and the propadiene is far higher than that of the comparative example.
TABLE 2
Catalyst and process for preparing same
MAPD conversion (%)
Selectivity (%)
Example 1
99.2
69.8
Example 2
98.7
78.2
Example 3
99.0
75.5
Example 4
97.8
77.4
Example 5
96.4
67.5
Example 6
97.9
70.5
Comparative example 1
95.1
52.3
Comparative example 2
95.3
71.8
Comparative example 3
96.1
46.5
Comparative example 4
93.3
55.6
Comparative example 5
95.4
53.9
Comparative example 6
94.2
58.1