阅读说明：本技术 一种裂解汽油用钯系选择加氢催化剂及其制备方法与应用 (Palladium-based selective hydrogenation catalyst for pyrolysis gasoline and preparation method and application thereof ) 是由 铁锴 乐毅 毛祖旺 彭晖 杨晨熹 穆玮 于 2020-05-20 设计创作，主要内容包括：本发明公开了一种钯系选择性加氢催化剂及其制备方法与应用,所述钯系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金属钯和助组分；其中,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％,所述助组分选自元素周期表上IVA族、VIB族、VIIB族元素中的至少一种。其中,在所述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钯系选择性加氢催化剂可以用于裂解汽油选择加氢反应。(The invention discloses a palladium selective hydrogenation catalyst and a preparation method and application thereof, wherein the palladium selective hydrogenation catalyst comprises an alumina carrier, metal palladium and an auxiliary component, wherein the metal palladium and the auxiliary component are loaded on the alumina carrier; the alumina carrier contains halogen elements, the halogen elements account for 0.01-3 wt% of the total weight of the alumina carrier, and the auxiliary component is at least one of elements in IVA group, VIB group and VIIB group of the periodic table of elements. Wherein, halogen-containing organic matters are added when the alumina carrier is prepared. The palladium selective hydrogenation catalyst obtained by the method can be used for selective hydrogenation reaction of pyrolysis gasoline.)

1. a palladium selective hydrogenation catalyst comprises an alumina carrier, metal palladium and a co-component, wherein the metal palladium and the co-component are loaded on the alumina carrier; wherein, a halogen element is added into the alumina carrier, and the halogen element accounts for 0.01-3 wt% of the total weight of the alumina carrier; the alumina carrier optionally contains Si element, and the Si element accounts for 0-1.5 wt% of the total weight of the carrier; the auxiliary component is selected from at least one of elements in IVA group, VIB group and VIIB group of the periodic table of elements.

2. The palladium-based selective hydrogenation catalyst according to claim 1,

the specific surface area of the alumina carrier is 10-150 m²(ii)/g, bulk density of 0.3-0.9 g/mL, pore volume of 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 one or more of La, Ce, Pr, Li, K and Ba elements, and the mass of the one or more elements accounts for 0-1.5 wt% of the total mass of the carrier.

3. The palladium-based selective hydrogenation catalyst according to claim 1,

the metal palladium accounts for 0.01-1 wt% of the total weight of the alumina carrier; and/or

The auxiliary component is selected from at least one of Sn, Pb, VIB group and VIIB group, preferably at least one of Sn, Pb, Cr, Mo and Mn, and more preferably accounts for 0.02-8 wt% of the total weight of the alumina carrier.

4. A method for preparing a palladium-based selective hydrogenation catalyst, preferably used for preparing the palladium-based selective hydrogenation catalyst according to any one of claims 1 to 3, comprising the steps of:

step 1, performing powder mixing treatment on powdery raw materials;

step 2, adding the acidic aqueous solution into the powder, and kneading and molding;

adding a halogen-containing organic substance, preferably a fluorine-containing organic substance and/or a chlorine-containing organic substance, to the powdery raw material in step 1 and/or to the acidic aqueous solution in step 2;

step 3, drying and roasting to obtain the alumina carrier;

and 4, loading metal palladium and an auxiliary component on the alumina carrier obtained in the step 3, and drying and roasting to obtain the palladium selective hydrogenation catalyst.

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 1.35 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, 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 is preferably selected 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 (0.5-2.5): 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 0-1.35 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 h, preferably 5-24 h; and/or

The roasting temperature is 800-1200 ℃, and preferably 1000-1200 ℃; the roasting time is 3-48 h, preferably 4-10 h.

10. The production method according to claim 4, wherein, in step 4,

the drying is carried out for 3-48 h at 50-200 ℃, preferably for 5-24 h at 60-150 ℃; and/or

The roasting is carried out for 2-10 h at 300-600 ℃, preferably for 4-8 h at 400-500 ℃.

11. The production method according to claim 4,

the amount of the fluorine-containing organic matter is 0.007-0.9 wt%, preferably 0.035-0.72 wt% of the total amount of the aluminum oxide powder, wherein the amount 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 matters is 0.007 to 1.8 wt%, preferably 0.035 to 0.9 wt% of the total dosage of the aluminum oxide powder, wherein the dosage of the chlorine-containing organic matters is based on the weight of chlorine element in the aluminum oxide powder.

12. The method according to any one of claims 4 to 11, wherein the fluorine-containing organic substance and/or the chlorine-containing organic substance is at least one selected from a fluorine-containing polymer and/or a chlorine-containing polymer, a fluorine-containing organic compound and/or a chlorine-containing organic compound.

13. The production method according to claim 12,

the fluorine-containing polymer 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 fluoropolymer and/or the chlorine-containing polymer have a particle diameter of less than 100 μm, preferably less than 50 μm; and/or

The fluorine-containing organic compound and/or chlorine-containing organic compound is a water-soluble organic compound containing fluorine elements and/or chlorine elements, and preferably, the fluorine-containing organic compound and/or chlorine-containing organic compound is selected from at least one of ethyl difluoroacetate, tetrafluoropropanol, trifluoroethanol, trifluoroacetal hydrate, chloroacetic acid, dichloroacetic acid, trichloroacetic acid and trichloroethanol.

14. A palladium-based selective hydrogenation catalyst obtained by the method according to any one of claims 4 to 13.

15. The palladium-based selective hydrogenation catalyst of one of claims 1 to 3 or the palladium-based selective hydrogenation catalyst of claim 14 for pyrolysis gasoline selective hydrogenation.

Technical Field

The invention belongs to the field of palladium catalysts, and particularly relates to a palladium selective hydrogenation catalyst and a preparation method thereof, which can be used for selective hydrogenation of pyrolysis gasoline.

Background

The pyrolysis gasoline is a liquid byproduct C in an ethylene device₅～C₉And the above fractions, the yield of which is second only to ethylene. The pyrolysis gasoline has complex composition and comprises hundreds of components such as straight-chain alkane, cyclane, monoolefin, diolefine, alkyne, aromatic hydrocarbon, organic compounds of nitrogen, sulfur, oxygen, chlorine and heavy metals, wherein the content of benzene, toluene and xylene is as high as 50-80 wt%, and the components are important aromatic hydrocarbon resources.

With the rapid development of the ethylene industry, the yield of the pyrolysis gasoline is synchronously and greatly improved, and the effective utilization of the pyrolysis gasoline has important significance for improving the comprehensive economic benefit of an ethylene device. Because of the unstable properties of the unsaturated hydrocarbon components in pyrolysis gasoline, polymerization easily occurs to produce low-polymerization-degree compounds and gums, which cannot be used directly. The industrial two-stage hydrogenation process is usually adopted to refine pyrolysis gasoline, wherein one-stage hydrogenation selectively removes diolefins, especially conjugated diolefins and olefin-based aromatic hydrocarbons, and two-stage hydrogenation removes mono-olefins and impurities such as sulfur, nitrogen, oxygen and the like.

At present, the pyrolysis gasoline one-stage selective hydrogenation catalyst applied in industrial production comprises two catalysts of palladium and nickel. Although the nickel-based catalyst has higher impurity poisoning resistance and gel-containing capacity, the hydrogenation activity and selectivity of the nickel-based catalyst are low. In contrast, palladium catalysts are widely used in pyrolysis gasoline hydrogenation units due to their low start-up temperature, good hydrogenation activity and selectivity.

In recent years, under the influence of heavy and inferior cracking raw materials, the content of diene, colloid, arsenic and other impurities in the cracked gasoline is increased, so that the palladium catalyst is quickly inactivated in the operation process and needs to be frequently activated and regenerated. Therefore, the preparation of palladium catalysts with high space velocity, high selectivity and high stability becomes the development trend of the conventional pyrolysis gasoline hydrogenation catalysts, so as to ensure long-period stable operation in the industrial production process.

Chinese patent CN1443829A discloses a catalyst for one-stage selective hydrogenation of pyrolysis gasoline, wherein the carrier adopts delta-phase alumina, the pore volume of the carrier is 0.6-0.9mL/g, the specific surface area is 140-170 m-²And the active component palladium is distributed on the surface of the carrier in an eggshell shape, and the load of the active component palladium is 0.05-0.4 percent of the mass of the catalyst. Although the catalyst has higher hydrogenation selectivity of diene, the hydrogenation activity and stability of the catalyst are still to be improved.

Chinese patent CN1429890A discloses a catalyst for selective hydrogenation of pyrolysis gasoline and a preparation method and application thereof, wherein a carrier of the catalyst adopts a titanium oxide-alumina compound, and the content of active component metal palladium loaded on the compound carrier accounts for 0.25-0.35% of the total mass of the catalyst. The catalyst has the characteristics of high activity, good selectivity and the like, but the impurity resistance of the catalyst still has room for improvement.

Chinese patent CN101700900A discloses a preparation method of ordered double-pore alumina and application thereof in pyrolysis gasoline hydrogenation. The alumina carrier takes aluminum alkoxide as a raw material, and a macroporous-mesoporous coexisting ordered double-pore structure is obtained after hydrolysis and roasting. The active component is loaded on the surface of the carrier by an impregnation method. Compared with the single-hole alumina catalyst, the catalyst has better catalytic performance in the selective hydrogenation reaction of the pyrolysis gasoline. However, the carrier is prepared from high-cost aluminum alkoxide, and the preparation process is complicated, so that the carrier is difficult to apply on a large scale in industrial production.

Disclosure of Invention

The invention mainly solves the technical problem that the selective hydrogenation catalyst for the pyrolysis gasoline with high airspeed, high selectivity and high stability is difficult to prepare in the prior art, and provides a novel catalyst for the selective hydrogenation of the pyrolysis gasoline. The catalyst has the advantages of high activity, good selectivity, strong glue holding capacity, simple preparation process and the like.

One purpose of the invention is to provide a palladium selective hydrogenation catalyst, which comprises an alumina carrier, metal palladium and an auxiliary component, wherein the metal palladium and the auxiliary component are loaded on the alumina carrier; the alumina carrier contains halogen elements, the halogen elements account for 0.01-3 wt% of the total weight of the alumina carrier, and the auxiliary component is at least one of elements in IVA group, VIB group and VIIB group of the periodic table of elements.

In a preferred embodiment, the metallic palladium is present in an amount of 0.01 to 1 wt%, preferably 0.05 to 0.5 wt%, based on the total weight of the alumina support.

In a preferred embodiment, the co-component is selected from at least one of Sn, Pb, group VIB, group VIIB.

In a further preferred embodiment, the co-component is selected from at least one of Sn, Pb, Cr, Mo, Mn.

In a further preferred embodiment, the co-component is present in an amount of 0.02 to 8 wt%, preferably 0.02 to 5 wt%, based on the total weight of the alumina support.

In a preferred embodiment, the alumina carrier has a specific surface area of 10 to 150m²(iv) per gram, bulk density of 0.3 to 0.9g/mL, pore volume of 0.25 to 1.00 mL/g.

In a more preferred embodiment, the alumina support has a specific surface area of 10 to 100m²The specific surface area per gram (g), the bulk density is 0.4-0.8 g/mL, the pore volume is 0.35-1.00 mL/g, and the water absorption rate is more than 40%.

The shape of the alumina carrier includes but is not limited to powder, granule, sphere, sheet, tooth sphere, strip or clover and other irregular strip shapes.

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 0.05 to 0.8 wt% of the total mass of the carrier, and the chlorine element accounts for 0.05 to 1 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 0.6 wt% of the total weight of the carrier.

In a preferred embodiment, one or more of La, Ce, Pr, Li, K and Ba elements are optionally contained in the alumina carrier, and the mass of the one or more elements accounts for 0-1.5 wt% of the total mass of the carrier, and is preferably 0-1 wt%.

Wherein, the elements such as La, Ce, Pr, Li, K, Ba and the like can further adjust parameters such as strength, specific surface area, pore volume and the like of the carrier.

The second object of the present invention is to provide a method for preparing the palladium-based selective hydrogenation catalyst, which comprises the following steps:

step 1, performing powder mixing treatment on powdery raw materials;

step 2, adding the acidic aqueous solution into the powder, and kneading and molding;

adding a halogen-containing organic substance, preferably a fluorine-containing organic substance and/or a chlorine-containing organic substance, to the powdery raw material in step 1 and/or to the acidic aqueous solution in step 2;

step 3, drying and roasting to obtain an alumina carrier;

and 4, loading metal palladium and an auxiliary component on the alumina carrier obtained in the step 3, and drying and roasting to obtain the palladium selective hydrogenation catalyst.

In a preferred embodiment, the metallic palladium is present in an amount of 0.01 to 1 wt%, preferably 0.05 to 0.5 wt%, based on the total weight of the alumina support.

In a preferred embodiment, the co-component is selected from at least one of the elements of groups IVA, VIB and VIIB of the periodic Table of the elements, preferably from at least one of Sn, Pb, VIB and VIIB, more preferably from at least one of Sn, Pb, Cr, Mo and Mn.

In a further preferred embodiment, the co-component is present in an amount of 0.02 to 8 wt%, preferably 0.02 to 5 wt%, based on the total weight of the alumina support.

In a preferred embodiment, the amount of the fluorine-containing organic compound is 0.007 to 0.9 wt%, preferably 0.035 to 0.72 wt% of the total amount of the aluminum oxide powder, wherein the amount of the fluorine-containing organic compound is based on the weight of the fluorine element.

In a further preferred embodiment, the chlorine-containing organic compound is used in an amount of 0.007 to 1.8 wt%, preferably 0.035 to 0.9 wt%, based on the weight of the chlorine element in the powder.

In a preferred embodiment, the fluorine-containing organic substance and/or chlorine-containing organic substance is at least one selected from fluorine-containing polymers and/or chlorine-containing polymers, fluorine-containing organic compounds and/or chlorine-containing organic compounds.

The preparation method is remarkably characterized in that organic matters containing halogen, particularly polymers containing halogen are added in the preparation process, so that the pore structure of the alumina carrier can be effectively adjusted. (1) The organic matters of the halogen are gasified and decomposed during roasting, a large number of micropores can be formed, the pore structure of the alumina carrier is favorably increased, and fluorine and chlorine can enter a framework in the decomposition process; (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.

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 polymer and/or chlorine-containing polymer is selected from, but not limited to, 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, vinyl chloride/vinylidene chloride copolymer.

In a further preferred embodiment, the fluorine-containing polymer 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 chloride, chlorinated polypropylene, chlorinated polyethylene.

In a still further preferred embodiment, the particle diameter of the fluoropolymer and/or the chlorine-containing polymer is less than 100. mu.m, preferably less than 50 μm.

In a preferred embodiment, the fluorine-containing organic compound and/or the chlorine-containing organic compound is a fluorine-containing element and/or a chlorine-containing water-soluble organic compound.

In a further preferred embodiment, the fluorine-containing organic compound and/or chlorine-containing organic compound is selected from, but not limited to, at least one of ethyl difluoroacetate, tetrafluoropropanol, trifluoroethanol, trifluoroacetaldehyde hydrate, chloroacetic acid, dichloroacetic acid, trichloroacetic acid and trichloroethanol.

In a still further preferred embodiment, the fluorine-containing organic compound and/or chlorine-containing organic compound is selected from, but not limited to, 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 mass content of Na and Fe is less than 0.1%.

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 1.35 wt%, preferably 0 to 0.9 wt%, and more preferably 0 to 0.45 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 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, ammonium carbonate and ammonium bicarbonate.

In a further preferred embodiment, the amount of the shaped pore-forming agent is 0 to 20 wt%, preferably 0 to 15 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 selected from at least one 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, preferably from at least one 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 0.1 to 10 wt%, preferably 0.1 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 2.5):1, preferably (0.6 to 2):1, and more preferably (0.8 to 1.5): 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 promoter is 0 to 1.35 wt% of the total amount of the alumina powder, wherein the amount of the soluble promoter is based on 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 the 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 24 hours.

In a preferred embodiment, in the step 3, the roasting temperature is 800-1200 ℃, and the roasting time is 3-48 h.

In a further preferred embodiment, in the step 3, the roasting temperature is 1000-1200 ℃, and the roasting time is 4-10 h.

In a more preferred embodiment, the heating rate is 30 to 150 ℃/h when the firing is performed at 600 ℃ or lower, and the heating rate is 280 ℃/h 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 step 4, the carrier may be loaded using a spraying method or an impregnation method commonly used in the preparation of catalysts: the active component precursor is prepared into an active component precursor solution, and then the active component precursor is loaded on the carrier by spraying or dipping. When the catalyst contains two or more active components, the spraying or impregnation can be carried out by a one-step method or a stepwise method.

In a preferred embodiment, in step 4, the drying is performed at 50 to 200 ℃ for 3 to 48 hours.

In a further preferred embodiment, in the step 4, the drying is performed at 60 to 150 ℃ for 5 to 24 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.

After spraying or dipping the auxiliary component, drying and roasting to obtain the finished product of the oxidizing catalyst.

The third object of the present invention is to provide a palladium-based selective hydrogenation catalyst obtained by the preparation method according to the second object of the present invention.

The fourth purpose of the invention is to provide one or three of the palladium-based selective hydrogenation catalysts for the purpose of the invention for the selective hydrogenation reaction of pyrolysis gasoline.

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, so that various performances of the alumina carrier are effectively improved, including high specific surface area, high pore volume, low bulk density and the like;

(2) the adopted carrier has better surface property, larger specific surface area and abundant pore structure, which is beneficial to the dispersion of active components;

(3) the palladium selective hydrogenation catalyst is used for hydrogenation reaction, particularly for selective hydrogenation of pyrolysis gasoline, so that the activity, selectivity and gel holding capacity of the catalyst can be obviously improved, and the catalyst can stably run for a long period;

(4) the preparation method is simple and easy to implement, green and environment-friendly, and can realize large-scale industrial production.

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 ]

200g of pseudo-boehmite powder, 6g of sesbania powder, 6g of starch and 0.24g of polyvinylidene fluoride powder are weighed, mixed uniformly in a mixer and then transferred into a kneader. 1g of concentrated nitric acid, 3g of oxalic acid and 0.88g of cerous nitrate hexahydrate are weighed and dissolved in 200mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 120 ℃ for 12h, roasting at 1180 ℃ for 6h, controlling the heating rate at 100 ℃/h when the temperature is below 600 ℃ and the heating rate at 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S1, wherein the F content is about 0.1 wt%, and the Ce content is about 0.2 wt%.

5mL of a palladium nitrate solution containing 50mgPd/mL was measured, 0.8g of lead nitrate was weighed and added to the palladium nitrate solution, diluted to 65mL with deionized water, and sprayed onto 100g of alumina carrier S1. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content of the catalyst is 0.25wt percent, and the Pb content of the catalyst is 0.5wt percent.

[ example 2 ]

Weighing 180g of pseudo-boehmite powder, 20g of fast deoxidized aluminum powder, 4g of sesbania powder, 8g of starch and 0.24g of polyvinylidene fluoride powder, uniformly mixing in a mixer, and transferring into a kneader. 1g of concentrated nitric acid, 2g of oxalic acid, 1g of citric acid, 0.88g of cerous nitrate hexahydrate and 0.86g of lanthanum nitrate hexahydrate are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 120 ℃ for 12h, roasting at 1180 ℃ for 6h, controlling the heating rate at 100 ℃/h when the temperature is below 600 ℃ and the heating rate at 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S2, wherein the F content is about 0.1 wt%, the Ce content is about 0.2 wt%, and the La content is 0.2 wt%.

5mL of a palladium nitrate solution containing 50mgPd/mL was measured, 0.8g of lead nitrate was weighed and added to the palladium nitrate solution, diluted to 65mL with deionized water, and sprayed onto 100g of alumina carrier S2. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content of the catalyst is 0.25wt percent, and the Pb content of the catalyst is 0.5wt percent.

[ example 3 ]

Weighing 180g of pseudo-boehmite powder, 20g of fast deoxidized aluminum powder, 6g of sesbania powder and 6g of starch, uniformly mixing in a mixer, and transferring into a kneader. 1g of concentrated nitric acid, 3g of oxalic acid, 0.33g of polytetrafluoroethylene concentrated dispersion (60 wt%), 0.73g of potassium nitrate and 0.86g of lanthanum nitrate hexahydrate are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 120 ℃ for 12h, roasting at 1180 ℃ for 6h, controlling the heating rate at 100 ℃/h when the temperature is below 600 ℃ and the heating rate at 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S3, wherein the F content is about 0.1 wt%, the K content is about 0.2 wt%, and the La content is about 0.2 wt%.

5mL of a palladium nitrate solution containing 50mgPd/mL was measured, diluted to 62mL with deionized water, and sprayed onto 100g of alumina support S3. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain an intermediate sample, wherein the Pd content of the intermediate sample is 0.25 wt%.

0.64g of stannous chloride was weighed out and dissolved in 62mL of deionized water and sprayed onto 100g of the above intermediate sample. The sprayed sample is dried for 6h at 120 ℃ and roasted for 8h at 450 ℃ to obtain the catalyst, wherein the Pd content is 0.25 wt% and the Sn content is 0.4 wt%.

[ example 4 ]

Weighing 180g of pseudo-boehmite powder, 20g of fast deoxidized aluminum powder, 6g of sesbania powder, 6g of starch and 0.45g of K-value 72-71 polyvinyl chloride powder, uniformly mixing in a mixer, and transferring into a kneader. 1g of concentrated nitric acid, 3g of oxalic acid, 0.73g of potassium nitrate and 0.86g of lanthanum nitrate hexahydrate are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 120 ℃ for 12h, roasting at 1180 ℃ for 6h, controlling the heating rate at 100 ℃/h when the temperature is below 600 ℃ and the heating rate at 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S4, wherein the Cl content is about 0.18 wt%, the K content is about 0.2 wt%, and the La content is about 0.2 wt%.

5mL of a palladium nitrate solution containing 50mgPd/mL was measured, diluted to 65mL with deionized water, and sprayed onto 100g of alumina support S4. The sprayed sample was dried at 120 ℃ for 6h and calcined at 450 ℃ for 8h to give an intermediate sample 1 having a Pd content of 0.25 wt%.

0.46g of ammonium heptamolybdate tetrahydrate was weighed out and dissolved in 62mL of deionized water and sprayed onto 100g of the above intermediate sample 1. The sprayed sample was dried at 120 ℃ for 6h and calcined at 450 ℃ for 8h to obtain an intermediate sample 2 having a Pd content of 0.25 wt% and a Mo content of 0.25 wt%.

0.58g of manganese dichloride was weighed out and dissolved in 62mL of deionized water and sprayed onto 100g of the above intermediate sample 2. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content is 0.25 wt%, the Mo content is 0.25 wt% and the Mn content is 0.25 wt%.

[ example 5 ]

Weighing 140g of pseudo-boehmite powder, 60g of fast deoxidized aluminum powder, 12g of methyl cellulose, 3g of polyvinyl alcohol, 0.15g of nano silicon oxide and 1.5g of urea, uniformly mixing in a mixer, and transferring into a kneader. 2.00g of concentrated nitric acid, 2.00g of oxalic acid, 1.64g of polytetrafluoroethylene concentrated dispersion (60 wt%) and 0.54g of barium nitrate were weighed and dissolved in 250mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 80 ℃ for 24h, roasting at 1000 ℃ for 10h, controlling the heating rate at 50 ℃/h when the temperature is below 600 ℃ and the heating rate at 150 ℃/h when the temperature is above 600 ℃, and naturally cooling to room temperature to obtain the alumina carrier S5, wherein the F content is about 0.5 wt%, the Si content is about 0.05 wt%, and the Ba content is about 0.2 wt%.

10mL of a palladium nitrate solution containing 50mgPd/mL was measured, 0.4g of lead nitrate was weighed and added to the palladium nitrate solution, diluted to 68mL with deionized water, and sprayed onto 100g of alumina carrier S5. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content of the catalyst is 0.5 wt% and the Pb content of the catalyst is 0.25 wt%.

[ example 6 ]

The method comprises the steps of roasting bayerite at 900 ℃ for 10 hours to obtain composite phase alumina of theta-alumina and alpha-alumina, weighing 60g of composite phase alumina, 140g of pseudo-boehmite powder, 12g of hydroxypropyl methyl cellulose, 5g of polyethylene oxide and 2g of ammonium carbonate, uniformly mixing in a mixer, and transferring into a kneader. 1g of concentrated nitric acid, 3g of oxalic acid and 1.27g of dichloroacetic acid are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 150 ℃ for 6h, roasting at 1200 ℃ for 4h, controlling the heating rate to be 120 ℃/h when the temperature is below 600 ℃, controlling the heating rate to be 250 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S6, wherein the Cl content of the alumina carrier S6 is about 0.5 wt%.

10mL of a palladium nitrate solution containing 50mgPd/mL was measured, diluted to 68mL with deionized water, and sprayed onto 100g of alumina support S6. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain an intermediate sample, wherein the Pd content of the intermediate sample is 0.5 wt%.

0.64g of stannous chloride was weighed out and dissolved in 68mL of deionized water and sprayed onto 100g of the above intermediate sample. The sprayed sample is dried for 6h at 120 ℃ and roasted for 8h at 450 ℃ to obtain the catalyst, wherein the Pd content is 0.5 wt% and the Sn content is 0.4 wt%.

[ example 7 ]

Weighing 140g of pseudo-boehmite powder, 60g of alumina trihydrate, 6g of sesbania powder, 5g of methyl cellulose, 4.4g of chlorinated polypropylene powder with the chlorine content of 32 wt% and 5g of polystyrene, uniformly mixing in a mixer, and transferring into a kneader. 1g of concentrated nitric acid and 3g of oxalic acid are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 110 ℃ for 10h, roasting at 1100 ℃ for 8h, controlling the heating rate to be 80 ℃/h when the temperature is below 600 ℃ and the heating rate to be 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S7, wherein the Cl content of the alumina carrier S7 is about 1.0 wt%.

1mL of a palladium nitrate solution containing 50mgPd/mL was measured, diluted to 65mL with deionized water, and sprayed onto 100g of alumina support S7. The sprayed sample is dried for 6h at 120 ℃ and roasted for 8h at 450 ℃ to obtain an intermediate sample, wherein the Pd content of the intermediate sample is 0.05 wt%.

2.3g of manganese dichloride was weighed out and dissolved in 65mL of deionized water and sprayed onto 100g of the above intermediate sample. And drying the sprayed sample at 120 ℃ for 6h, and roasting at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content of the catalyst is 0.05 wt%, and the Mn content of the catalyst is 1.0 wt%.

[ example 8 ]

Weighing 140g of pseudo-boehmite powder, 20g of alumina trihydrate, 20g of fast deoxidized alumina powder, 20g of composite phase alumina powder, 6g of sesbania powder, 0.19g of polytetrafluoroethylene powder, 3g of polyethylene glycol and 1.8g of ammonium bicarbonate, uniformly mixing in a mixer, and transferring into a kneader. 1.00g of concentrated nitric acid, 3.00g of oxalic acid and 0.99g of trichloroethanol are weighed and dissolved in 210mL of deionized water to prepare a mixed solution. And slowly adding the mixed solution into the material of the kneading machine, fully kneading, extruding, molding and granulating to obtain particles with the particle size of 4-6 mm. Drying the particles at 110 ℃ for 10h, roasting at 1100 ℃ for 8h, controlling the heating rate to be 80 ℃/h when the temperature is below 600 ℃ and the heating rate to be 200 ℃/h when the temperature is above 600 ℃, and finally naturally cooling to room temperature to obtain the alumina carrier S8, wherein the F content is about 0.1 wt%, and the Cl content is about 0.5 wt%.

2mL of a palladium nitrate solution containing 50mgPd/mL was measured, diluted to 70mL with deionized water, and sprayed onto 100g of the alumina support S8. The sprayed sample was dried at 120 ℃ for 6h and calcined at 450 ℃ for 8h to give an intermediate sample 1 having a Pd content of 0.1 wt%.

3.68g of ammonium heptamolybdate tetrahydrate are weighed out and dissolved in 70mL of deionized water and sprayed onto 100g of the above intermediate sample 1. The sprayed sample was dried at 120 ℃ for 6 hours and calcined at 450 ℃ for 8 hours to obtain an intermediate sample 2 having a Pd content of 0.1 wt% and a Mo content of 2.0 wt%.

2.3g of manganese dichloride was weighed out and dissolved in 70mL of deionized water and sprayed onto 100g of the above intermediate sample 2. The sprayed sample is dried at 120 ℃ for 6h and roasted at 450 ℃ for 8h to obtain the catalyst, wherein the Pd content is 0.1 wt%, the Mo content is 2.0 wt% and the Mn content is 1.0 wt%.

Comparative example 1

The procedure of example 1 was repeated except that: when the alumina carrier is prepared, 0.24g of polyvinylidene fluoride powder is not adopted, and the catalyst is obtained by the same process of loading the catalytic component under the same conditions.

Comparative example 2

The procedure of example 1 was repeated except that: and replacing 0.24g of polyvinylidene fluoride powder with 0.45g of potassium fluoride (the fluorine content of the two is the same), and loading the catalytic component under the same conditions to obtain the catalyst.

Comparative example 3

The procedure of example 1 was repeated except that: replacing 0.24g of polyvinylidene fluoride powder (the fluorine content of the polyvinylidene fluoride powder is the same) with (0.45g of potassium fluoride and 0.11g of pentane), wherein the potassium fluoride is added into the powdery raw material, the pentane is added into the acidic aqueous solution, the other conditions are the same, and the process of loading the catalytic component is the same, so that the catalyst is obtained.

Comparative example 4

The procedure of example 1 was repeated except that: 0.29g of ammonium fluoride is used for replacing 0.24g of polyvinylidene fluoride powder (the fluorine content of the polyvinylidene fluoride powder and the fluorine content of the polyvinylidene fluoride powder are the same), and the process of loading the catalytic component is the same under the same other conditions, so that the catalyst is obtained.

[ Experimental example ]

The reaction evaluation was carried out using an adiabatic bed. Taking 100mL of each of the catalysts prepared in examples 1-4 and comparative examples 1-4, the hydrogen pressure is 1.5MPa, and the temperature is 180 DEG CAnd reducing for 2h under the condition that the hydrogen flow is 500 mL/min. The pressure of hydrogen is 2.8MPa, the inlet temperature is 42 ℃, and the space velocity of fresh oil is 4.5h^-1(Total space velocity 13.5 h)^-1) The test is carried out by introducing full-range pyrolysis gasoline (C5-C9) under the condition that the volume ratio of hydrogen to oil is 100: 1. The content of colloid in the raw material of the pyrolysis gasoline is less than 120mg/100g of oil, the diene value is 35.7g of iodine/100 g of oil, and the bromine number is 58.3g of bromine/100 g of oil. The evaluation results are shown in Table 1.

TABLE 1

[ Experimental example 2 ]

The test evaluation was carried out for 500h using an adiabatic bed. The reduction process of Experimental example 1 was repeated, taking 100mL each of the catalysts prepared in example 2 and comparative example 1. The pressure of hydrogen is 2.8MPa, the inlet temperature is 42 ℃, and the space velocity of fresh oil is 4.5h^-1(Total space velocity 13.5 h)^-1) Introducing full-range pyrolysis gasoline (C) under the condition that the volume ratio of hydrogen to oil is 100:1₅～C₉) The raw materials were tested. The content of colloid in the raw material of the pyrolysis gasoline is less than 120mg/100g of oil, the diene value is 34.6g of iodine/100 g of oil, and the bromine number is 57.9g of bromine/100 g of oil. The evaluation results are shown in Table 2.

Table 2: