CN112547112B - Palladium catalyst for removing trace sulfide in benzene - Google Patents

Palladium catalyst for removing trace sulfide in benzene Download PDF

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CN112547112B
CN112547112B CN202011620047.XA CN202011620047A CN112547112B CN 112547112 B CN112547112 B CN 112547112B CN 202011620047 A CN202011620047 A CN 202011620047A CN 112547112 B CN112547112 B CN 112547112B
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catalyst
benzene
palladium
stirring
microemulsion
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CN112547112A (en
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郑晓广
摆向宇
梁巍
李世强
李文博
靳鹏
赵堃雨
宋斯玉
段飞桐
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Henan Shenma Catalyzing Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
    • B01J29/44—Noble metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
    • B01J29/42—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing iron group metals, noble metals or copper
    • B01J29/46—Iron group metals or copper
    • B01J35/391—
    • B01J35/398—
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
    • C07C7/148—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound
    • C07C7/163—Purification; Separation; Use of additives by treatment giving rise to a chemical modification of at least one compound by hydrogenation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/10—After treatment, characterised by the effect to be obtained
    • B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
    • B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Abstract

The invention discloses a palladium catalyst for removing trace sulfide in benzene, which comprises an active component, an auxiliary agent and a porous carrier, the auxiliary agent and the active component are wrapped by the porous carrier to form a core-shell structure, the active component is palladium, the auxiliary agent is one or more of cerium oxide and copper oxide, nickel oxide or ferric oxide, the porous carrier is a ZSM-5 molecular sieve, CO-520 and cyclohexane are added into the prepared active component, the auxiliary agent precipitate and the ZSM-5 molecular sieve precursor to form microemulsion, so that the generated active component and the groups in the precursor precipitated by the auxiliary agent are combined with the hydroxyl group of the generated molecular sieve, and the like, thereby forming the core-shell catalyst, the catalyst prepared by the method has the characteristics of high sulfur capacity, small loss of active metal, reproducibility and easy realization of industrial production, can be directly applied to the fine desulfurization process in the cyclohexene production process under the condition of not changing the working condition.

Description

Palladium catalyst for removing trace sulfide in benzene
Technical Field
The invention belongs to the technical field of chemical industry, and particularly relates to a palladium catalyst for removing trace sulfide in benzene.
Background
The method is characterized in that cyclohexene is an important organic synthesis intermediate and is widely applied to production of chemical industry products, the direct preparation of cyclohexene by adopting low-price benzene partial hydrogenation has great economic benefit, in the process, the benzene partial hydrogenation ruthenium-based catalyst is the most critical catalyst, but trace sulfur easily poisons the benzene partial hydrogenation catalyst, and the activity and selectivity of the catalyst are greatly reduced in production. Tests show that when the content of sulfide in the raw material benzene is 0.1ppm, the activity of part of hydrogenation catalyst begins to be obviously reduced, and when the cumulative concentration of sulfide in the fed benzene reaches 20ppm, part of hydrogenation catalyst loses industrial application value. Therefore, the deep desulfurization catalyst in the process route of the partial hydrogenation of the benzene is used for guaranteeing the activity of the partial hydrogenation catalyst of the benzene. In the production process of petroleum refined benzene or coking refined benzene, although series of sulfide removal works are carried out, such as extractive distillation by using sulfolane, formylmorpholine and the like as solvents and critical hydrodesulfurization gradually popularized in recent years, the removal of trace sulfur in refined benzene to a level which cannot be detected by the existing testing means cannot be achieved, so that a fine desulfurization process needs to be added in the cyclohexene production process.
Adsorption desulfurization belongs to a common fine desulfurization process, however, the existing solid adsorbent has the defects of needing to change working conditions, being incapable of regeneration or low sulfur capacity, and the adsorbent is frequently replaced or regenerated.
Disclosure of Invention
The invention aims to provide a palladium catalyst for removing trace sulfide in benzene, which has the characteristics of high sulfur capacity, small loss of active metal, reproducibility and easiness in realizing industrial production, and can be directly applied to a fine desulfurization process in a cyclohexene production process under the condition of not changing working conditions.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
a palladium catalyst for removing trace sulfide in benzene comprises an active component, an auxiliary agent and a porous carrier, wherein the auxiliary agent and the active component are wrapped by the porous carrier to form a core-shell structure, the active component is palladium, the auxiliary agent is one or more of cerium oxide, copper oxide, nickel oxide or iron oxide, and the porous carrier is a ZSM-5 molecular sieve.
Further, the mass ratio of the active component to the catalyst is 0.5-3%, the mass ratio of the auxiliary agent to the catalyst is 1-5%, and the balance is a porous carrier.
In the additives, cerium oxide is a first additive, one or more of the rest oxides is a second additive, and the mass ratio of the first additive to the second additive is 1: 1.
a method for preparing the palladium catalyst for removing trace sulfide in benzene comprises the following steps:
step 1: adding a first alkali compound into first part of water, stirring, and adding a mixture of water and alkali compound in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion A;
step 2: adding a proper amount of hydrochloric acid and a second part of water into the palladium salt and the auxiliary salt, stirring, and adding the palladium salt and the auxiliary salt in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion B;
and step 3: mixing the microemulsion A and the microemulsion B, adding a proper amount of a second alkali compound after stirring for a period of time, slowly adding an organic amine template after continuously stirring for a period of time, and uniformly stirring to obtain a microemulsion C;
and 4, step 4: adding a certain amount of aluminum source compound into the microemulsion C under the stirring action, slowly adding a proper amount of silicon source compound after the aluminum source is uniformly dispersed, continuously stirring until the aluminum source is in a white emulsion state, then transferring the white emulsion state into a hydrothermal synthesis kettle, and crystallizing for a period of time under the hydrothermal synthesis condition;
and 5: carrying out solid-liquid separation, washing, drying and roasting on the crystallized material;
step 6: and reducing the roasted material to obtain the catalyst.
In the raw materials, the aluminum source compound and the silicon source compound are SiO2And Al2O3Meter, SiO2And Al2O3The molar ratio of (80-100) to (1), organic amine template and Al2O3The molar ratio of (4-8): 1, second base compound with Al2O3The molar ratio of (4-8): 1 total water content and Al2O3The molar ratio of (2000-4000): 1.
further, in the step 1, the first alkali compound is sodium hydroxide, potassium hydroxide or concentrated ammonia water.
Further, in the step 2, the palladium salt is palladium chloride or palladium nitrate, and the auxiliary salt is one or more of nitrate, sulfate, acetate and chloride.
Further, in the step 3, the second alkalide is sodium hydroxide, potassium hydroxide or concentrated ammonia water, and the organic amine template is tetrapropylammonium hydroxide.
Further, in the step 4, the hydrothermal synthesis condition is crystallization at 150-170 ℃ for 48-72 h.
Further, heating to 50-100 ℃ at the speed of 1-15 ℃/min during drying in the step 5, and drying for 1-5 h; when in roasting, the temperature is raised from room temperature to 150-700 ℃ at the speed of 1-15 ℃/min for 2-10 h.
Further, the reduction in step 6 includes gas phase reduction or liquid phase reduction; introducing hydrogen, carbon monoxide or ethylene during gas phase reduction at 80-200 deg.C for 1-10h, at 120 deg.C and 160 deg.C, and with space velocity not exceeding 6h-1(ii) a The pH value is controlled to be 8-12 during liquid phase reduction, and sodium borohydride, hydrazine hydrate, aldehydes, carboxylic acids or olefins are adopted.
Compared with the prior art, the invention has the following beneficial effects:
1) in the preparation process, CO-520 and cyclohexane are added to form microemulsion, so that the generated active component is combined with groups in a precursor of the auxiliary precipitation and hydroxyl groups of the generated molecular sieve, and the like, thereby forming the core-shell catalyst; 2) the catalyst has a step catalysis function, when in desulfurization, only sulfides can enter a pore channel of a ZSM-5 molecular sieve by utilizing the selectivity and the adsorption characteristic of the ZSM-5 molecular sieve, so that the desulfurization selectivity is improved, and then the sulfides are adsorbed by utilizing the high specific surface area and the super adsorption characteristic of a high-dispersion active component palladium, so that trace sulfides in benzene can be removed to the extent that the trace sulfides cannot be detected by the conventional analysis means, which is difficult to achieve when the conventional desulfurization active component is loaded on a porous carrier; 3) the molecular sieve structure protects the active and auxiliary components, so that the adsorbed sulfur compound is not easy to desorb, and the active component is not easy to lose in the use process, thereby further improving the desulfurization efficiency and prolonging the service life of the catalyst.
Drawings
FIG. 1 is a transmission electron micrograph of a catalyst of the present invention;
figure 2 is an XRD pattern of the catalyst of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is described in detail below with reference to specific examples and experimental data, and it should be understood that the specific examples described herein are only for explaining the present invention and are not intended to limit the present invention.
The invention discloses a palladium catalyst for removing trace sulfide in benzene, which comprises an active component, an auxiliary agent and a porous carrier, wherein the auxiliary agent and the active component are wrapped by the porous carrier to form a core-shell structure, the active component is palladium, the auxiliary agent is one or more of cerium oxide, copper oxide, nickel oxide or iron oxide, and the porous carrier is a ZSM-5 molecular sieve.
When the catalyst is applied to removing trace sulfides in benzene, firstly, the selectivity and the adsorption characteristic of the ZSM-5 molecular sieve are utilized, only sulfides can enter the pore channels of the ZSM-5 molecular sieve, the desulfurization selectivity is improved, and then, the high specific surface area and the super adsorption characteristic of the high-dispersion active component palladium are utilized to adsorb the sulfides, so that the trace sulfides in the benzene can be removed to the extent that the trace sulfides cannot be detected by the conventional analysis means, which is difficult to achieve when the conventional desulfurization active component is loaded on a porous carrier.
As an alternative, the mass ratio of the active component in the catalyst is 0.5-3%, the mass ratio of the auxiliary agent in the catalyst is 1-5%, and the balance is a porous carrier.
Optionally, the cerium oxide is a first aid, one or more of copper oxide, nickel oxide or iron oxide is a second aid, and the mass ratio of the first aid to the second aid is 1: 1, preferably, the mass ratio of cerium oxide to copper oxide, nickel oxide or iron oxide is 1: 1, to increase the specific surface area of the active component, thereby increasing the sulfur capacity.
The invention also discloses a method for removing trace sulfide in benzene by using the palladium catalyst, which comprises the following steps:
step 1: adding a first alkali compound into first part of water, stirring, and adding a mixture of water and alkali compound in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion A;
step 2: adding a proper amount of hydrochloric acid and a second part of water into the palladium salt and the auxiliary salt, stirring, and adding the palladium salt and the auxiliary salt in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion B;
and step 3: mixing the microemulsion A and the microemulsion B, adding a proper amount of a second alkali compound after stirring for a period of time, slowly adding an organic amine template after continuously stirring for a period of time, and uniformly stirring to obtain a microemulsion C;
and 4, step 4: adding a certain amount of aluminum source compound into the microemulsion C under the stirring action, slowly adding a proper amount of silicon source compound after the aluminum source is uniformly dispersed, continuously stirring until the aluminum source is in a white emulsion state, then transferring the white emulsion state into a hydrothermal synthesis kettle, and crystallizing for a period of time under the hydrothermal synthesis condition;
and 5: carrying out solid-liquid separation, washing, drying and roasting on the crystallized material;
step 6: and reducing the roasted material to obtain the catalyst.
In the raw materials, the aluminum source compound and the silicon source compound are SiO2And Al2O3Meter, SiO2And Al2O3The molar ratio of (80-100) to (1), organic amine template and Al2O3The molar ratio of (4-8): 1, second base compound with Al2O3The molar ratio of (4-8): 1 total water content and Al2O3The molar ratio of (2000-4000): 1.
CO-520 and cyclohexane are added in the preparation process to form microemulsion, so that the generated active component is combined with the groups in the precursor precipitated by the aid and the hydroxyl groups of the generated molecular sieve, and the core-shell catalyst is formed.
In some embodiments, the first base compound in step 1 may be selected from sodium hydroxide, potassium hydroxide or concentrated ammonia, preferably sodium hydroxide, to ensure the formation of a precursor for the active component and the builder precipitate.
In some embodiments, the palladium salt in step 2 may be selected from palladium chloride or palladium nitrate, preferably palladium chloride, and the promoter salt may be selected from one or more of nitrate, sulfate, acetate, and chloride, preferably nitrate.
In some embodiments, the second alkali compound in step 3 can be selected from sodium hydroxide, potassium hydroxide or concentrated ammonia, preferably concentrated ammonia, and the organic amine template is preferably tetrapropylammonium hydroxide to ensure the formation of the ZSM-5 molecular sieve.
In some embodiments, the aluminum source compound may be selected from one or more of aluminum sulfate, sodium aluminate, aluminum nitrate, aluminum isopropoxide, preferably aluminum isopropoxide, and the silicon source compound may be selected from one or more of silica sol, methyl orthosilicate, and ethyl orthosilicate, preferably ethyl orthosilicate.
In some embodiments, the hydrothermal synthesis conditions in step 4 may be selected from 150-170 ℃ for 48-72 h, preferably 150 ℃ for 72h, to ensure the formation of the ZSM-5 molecular sieve.
In some embodiments, the drying in step 5 may be performed by heating to 50-100 ℃ at a rate of 1-15 ℃/min for 1-5h, preferably at a rate of 5 ℃/min for 100 ℃ for 2 h; the heat treatment can be carried out for 2-10 h at 1-15 ℃/min from room temperature to 150-700 ℃, preferably for 5h at 5 ℃/min from room temperature to 500 ℃, so that the heat treatment process of the catalyst precursor is ensured to be heated uniformly, the phenomena of cracking and the like of the wet-based granular catalyst caused by rapid heating are prevented, and more importantly, the good dispersion state of the active metal component palladium atoms in the catalyst is ensured.
In some embodiments, the reduction in step 6 may be selected from gas phase reduction in which hydrogen and oxygen are introduced or liquid phase reduction in whichCarbonizing carbon or ethylene at 80-200 deg.C for 1-10h, at 120 deg.C and 160 deg.C, and at airspeed of 6h or less-1(ii) a And (2) controlling the pH value to be 8-12 during liquid-phase reduction, adopting sodium borohydride, hydrazine hydrate, aldehydes, carboxylic acids or olefins, preferably carrying out gas-phase reduction, wherein the volume ratio of the reduction atmosphere is 30: 70 of mixed gas of nitrogen and hydrogen, the reduction temperature is 100 ℃, the reduction time is 2 hours, and the space velocity is 6 hours-1(ii) a To ensure that the palladium oxide is reduced to metallic palladium so that the sulphide can be adsorbed.
The present invention is described in detail below with reference to specific examples. The desulfurization performance of the catalyst was evaluated by using a small fixed bed reactor with a 50 g loading, and the sulfide contents in the feed aromatic hydrocarbon and the discharge aromatic hydrocarbon were analyzed by using a total sulfur analyzer and a gas chromatograph.
Example 1
Adding 2.7 g of NaOH into 400ml of water, stirring, adding 800ml of CO-520 and 1600 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion A, adding 0.8g of palladium chloride, 8.6 g of cerous nitrate hexahydrate and 4.8g of copper nitrate trihydrate into 0.5ml of hydrochloric acid and 300ml of water, stirring, adding 1200 ml of CO-520 and 2400 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion B, mixing the microemulsion A with the microemulsion B, adding 12 ml of concentrated ammonia water after stirring for a period of time, slowly adding 15.7g of TPAOH after continuously stirring for a period of time, uniformly stirring to obtain a microemulsion C, adding 7.9 g of aluminum isopropoxide into the microemulsion C under the stirring action, slowly adding 320 g of TEOS after the aluminum isopropoxide is uniformly dispersed, continuously stirring to a white emulsion state, then transferring to a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5 h; placing the heat-treated material into a fixed bed reactor, performing nitrogen replacement on the reactor, performing gas phase reduction at 100 ℃ by using mixed gas with the volume ratio of nitrogen to hydrogen being 30: 70, wherein the reduction holding time is 2 hours, and the airspeed is 6 hours-1After reduction, a palladium catalyst for removing trace sulfide in benzene was obtained, and the catalyst was labeled as sample 1.
Example 2
Adding 2.9 g of NaOH into 650ml of water and stirring, adding 850ml of CO-520 and 2550 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion A, adding 1.7 g of palladium chloride, 8.6 g of cerous nitrate hexahydrate and 4.8g of copper nitrate trihydrate into 0.5ml of hydrochloric acid and 450ml of water and stirring, adding 850ml of CO-520 and 2550 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion B, mixing the microemulsion A and the microemulsion B, adding 19 ml of concentrated ammonia water after stirring for a period of time, slowly adding 25.0g of TPAOH after continuously stirring for a period of time, and uniformly stirring to obtain a microemulsion C, adding 3 g of isopropanol aluminum into the microemulsion C under the stirring action, slowly adding 320 g of TEOS after the isopropanol aluminum is uniformly dispersed, continuously stirring to be in a white emulsion state, then transferring to a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5 h; placing the heat-treated material into a fixed bed reactor, performing nitrogen replacement on the reactor, performing gas phase reduction at 100 ℃ by using mixed gas with the volume ratio of nitrogen to hydrogen being 30: 70, wherein the reduction holding time is 2 hours, and the airspeed is 6 hours-1After reduction, a palladium catalyst for removing trace sulfide in benzene was obtained, and this catalyst was labeled as sample 2.
Example 3
Adding 3.3 g of palladium chloride, 5.3 g of cerium nitrate hexahydrate and 3.5 g of nickel nitrate hexahydrate into 0.5ml of hydrochloric acid and 400ml of water, stirring, adding 850ml of CO-520 and 2000ml of cyclohexane, stirring to form a microemulsion B, mixing the microemulsion A and the microemulsion B, stirring for a period of time, adding 12 ml of concentrated ammonia water, stirring for a period of time, slowly adding 21g of TPAOH, stirring to obtain a microemulsion C, adding 7.0 g of aluminum isopropoxide into the microemulsion C under the stirring action, slowly adding 323 g of TEOS after the aluminum isopropoxide is dispersed uniformly, stirring continuously to a white emulsion state, transferring to a hydrothermal synthesis kettle, and crystallizing at 150 ℃ for 72 hours; the crystallized material is subjected to solid-liquid separation and washing, and the washed material is subjected to solid-liquid separation and washingPutting the materials into a drying oven, heating to 100 ℃ at the speed of 5 ℃/min, and drying for 2 h; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5 h; placing the heat-treated material into a fixed bed reactor, performing nitrogen replacement on the reactor, performing gas phase reduction at 100 ℃ by using mixed gas with the volume ratio of nitrogen to hydrogen being 30: 70, wherein the reduction holding time is 2 hours, and the airspeed is 6 hours-1After reduction, a palladium catalyst for removing trace sulfide in benzene was obtained, and this catalyst was labeled as sample 3.
Example 4
Adding 2.6 g of NaOH into 500ml of water, stirring, adding 800ml of CO-520 and 2000ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion A, adding 5 g of palladium chloride, 2.0 g of cerium nitrate hexahydrate and 1.8 g of ferric nitrate nonahydrate into 0.5ml of hydrochloric acid and 400ml of water, stirring, adding 850ml of CO-520 and 2000ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion B, mixing the microemulsion A and the microemulsion B, adding 16 ml of concentrated ammonia water after stirring for a period of time, slowly adding 24.8g of TPAOH after continuously stirring for a period of time, and stirring uniformly to obtain a microemulsion C, adding 7.1 g of aluminum isopropoxide into the microemulsion C under the stirring action, slowly adding 327 g of TEOS after the aluminum isopropoxide is dispersed uniformly, continuously stirring to a white emulsion state, then transferring to a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5 h; placing the heat-treated material into a fixed bed reactor, performing nitrogen replacement on the reactor, performing gas phase reduction at 100 ℃ by using mixed gas with the volume ratio of nitrogen to hydrogen being 30: 70, wherein the reduction holding time is 2 hours, and the airspeed is 6 hours-1After reduction, a palladium catalyst for removing trace sulfide in benzene was obtained, and this catalyst was labeled as sample 4.
Example 5
The procedure is as in example 1, except that 4.8g of copper nitrate trihydrate are replaced by 4.0 g of cerium nitrate hexahydrate, otherwise the catalyst is as in example 1 and is designated sample 5
Comparative example 1
The catalyst sample was labeled as comparative sample 1, the same as example 1, except that no CO-520 and cyclohexane were added during the preparation.
Comparative example 2
Adding 7.9 g of aluminum isopropoxide into the microemulsion C under the stirring action, slowly adding 320 g of TEOS after the aluminum isopropoxide is uniformly dispersed, continuously stirring until the mixture is in a white emulsion state, then transferring the mixture into a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; and then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5h to obtain the ZSM-5 molecular sieve, placing the ZSM-5 molecular sieve in a beaker, adding 50ml of water, and stirring to form a suspension A.
Adding 2.7 g of NaOH into 50ml of water and stirring to form a solution B, adding 0.8g of palladium chloride, 8.6 g of cerous nitrate hexahydrate and 4.8g of copper nitrate trihydrate into 0.5ml of hydrochloric acid and 50ml of water and stirring to form a solution C, simultaneously adding the solution B and the solution C into the suspension A, stirring, after the reaction is finished, carrying out solid-liquid separation and washing on the materials, putting the washed materials into a drying oven, heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 hours; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for heat treatment for 5h, putting the heat-treated material into a fixed bed reactor, carrying out nitrogen replacement on the reactor, then carrying out gas phase reduction at the temperature of 100 ℃ by using mixed gas of nitrogen and hydrogen with the volume ratio of 30 to 70, wherein the reduction holding time is 2 hours, and the airspeed is 6h-1After reduction, the palladium catalyst was obtained to remove trace amount of sulfides in benzene, and the catalyst was labeled as comparative sample 2.
Comparative example 3
Adding 2.7 g of NaOH into 400ml of water, stirring, adding 800ml of CO-520 and 1600 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion A, adding 0.8g of palladium chloride, 8.6 g of cerous nitrate hexahydrate and 4.8g of copper nitrate trihydrate into 0.5ml of hydrochloric acid and 300ml of water, stirring, adding 1200 ml of CO-520 and 2400 ml of cyclohexane after dissolving, continuously stirring uniformly to form a microemulsion B, mixing the microemulsion A and the microemulsion B, and stirringAdding 12 ml of concentrated ammonia water after a period of time, continuously stirring for a period of time, slowly adding 328 g of TEOS, continuously stirring until the mixture is in a white emulsion state, then transferring the mixture into a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5 h; placing the heat-treated material into a fixed bed reactor, performing nitrogen replacement on the reactor, performing gas phase reduction at 100 ℃ by using mixed gas with the volume ratio of nitrogen to hydrogen being 30: 70, wherein the reduction holding time is 2 hours, and the airspeed is 6 hours-1After reduction, the palladium catalyst was obtained to remove trace amount of sulfides in benzene, and the catalyst was labeled as comparative sample 3.
Comparative example 4
Adding 7.9 g of aluminum isopropoxide into the microemulsion C under the stirring action, slowly adding 320 g of TEOS after the aluminum isopropoxide is uniformly dispersed, continuously stirring until the mixture is in a white emulsion state, then transferring the mixture into a hydrothermal synthesis kettle, and crystallizing for 72 hours at 150 ℃; carrying out solid-liquid separation and washing on the crystallized material, putting the washed material into a drying oven, and heating to 100 ℃ at the speed of 5 ℃/min and drying for 2 h; and then heating the dried material from room temperature to 500 ℃ at the speed of 5 ℃/min for 5h to obtain the ZSM-5 molecular sieve, and marking the catalyst as a comparative sample 4.
Comparative example 5
The procedure is the same as in example 1 except that cerium nitrate hexahydrate and copper nitrate trihydrate are not added during the preparation, otherwise the procedure is the same as in example 1 and the catalyst sample is labeled as comparative sample 5.
The above examples and comparative examples were evaluated for desulfurization performance by the following methods:
50 g of the catalyst prepared by the method is filled into a fixed bed reactor with the height-diameter ratio of 4.5 and the effective volume of 70ml, and a small amount of activated alumina with the same specification is filled at the two ends of the fixed bed reactor; sulfur-free benzene was used to formulate a feed benzene having a sulfur content (thiophene) of 3 wtppm. Heating a fixed bed reactor to 118-122 ℃, and pressing the solutionThe space velocity is 3.5 h-1And adjusting the flow rate of the constant flow pump. After the preparation work is ready, the transverse flow pump is started to carry out a deep desulfurization test, and the reaction pressure is maintained at 0.1 MPa. The reactor outlet sulfide concentration was monitored at a frequency of times/4 hours until the reactor outlet sulfide concentration was 0.01wtppm, and the amount of benzene actually consumed as the sulfur-containing feed was recorded.
The sulfide removal capacity (sulfur capacity: g sulfide/kg catalyst) of the catalyst was calculated from the amount of catalyst used and the total amount of sulfide, and the results are shown in Table 1.
TABLE 1 comparison of sulfur capacity of samples of each catalyst
Figure DEST_PATH_IMAGE001
As can be seen from Table 1, the sulfur capacity of the core-shell catalyst prepared by the method is more than 1.8 g (thiophene)/kg (cat), and the sulfur capacity of the comparative sample 1 is only 1.2 g (thiophene)/kg (cat), which shows that the method designs the catalyst into a core-shell structure, effectively improves the selective adsorption of the catalyst on sulfur, and further increases the sulfur capacity, and the sulfur capacity of the sample 5 is lower than that of the samples of other examples, which shows that the sulfur capacity of the catalyst can be improved when two additives are mixed; the comparative sample 2 is a ZSM-5 molecular sieve synthesized firstly, and then active components and auxiliary agents are precipitated on the pore passages or the outer surfaces of the molecular sieve, the preparation method is similar to the impregnation method, and the table shows that the sulfur capacity of the catalyst prepared by the method is only 0.9 g (thiophene)/kg (cat) which is far lower than that of the catalyst prepared by the invention; comparative sample 3 has a core-shell structure, but the material coated with it is pure SiO2Molecular sieves with a sulfur capacity of 1.4 g (thiophene)/kg (cat), inferior to the ZSM-5 molecular sieves coated in accordance with the present invention, indicating that the sulfur capacity is also related to the structure of the coating material; the comparative sample 4 is a pure ZSM-5 molecular sieve, the sulfur capacity of which is 0.8g (thiophene)/kg (cat), which indicates that the ZSM-5 molecular sieve has certain capability of adsorbing sulfides, but the sulfur capacity of which is lower than that of the catalyst of the invention, and indicates that the sulfur capacity of the catalyst of the invention is improved through the improved design of the invention; comparative sample 5, a core-shell catalyst without an added adjunct, has a sulfur capacity of 1.4 g (thiophene)/kg (cat) which is much lower than that of sample 1The addition of the auxiliary agent is shown to effectively improve the sulfur capacity.
The catalyst after reaction can be desorbed under the condition of pressure reduction or vacuum pumping, and can be matched with inert gas purging to improve the desorption effect and quickly realize the regeneration of the catalyst. Due to the protection effect of the molecular sieve on the active component and the auxiliary agent, the catalyst can be repeatedly regenerated and used for many times, and has longer service life compared with the traditional adsorbent.
In order to verify that the catalyst prepared by the invention has a core-shell structure and the outer layer is wrapped by the ZSM-5 molecular sieve, a sample in the embodiment 1 is subjected to TEM and XRD characterization, the TEM result is shown in figure 1 and the XRD result is shown in figure 2, as can be seen from figure 1, the catalyst with the core-shell structure can be synthesized by adopting the preparation method disclosed by the invention, as can be seen from figure 2, the molecular sieve with the shell structure being ZSM-5 is successfully synthesized, and the active component and the auxiliary agent cannot be displayed in an XRD spectrogram due to the wrapping.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

1. A palladium catalyst for removing trace sulfide in benzene comprises an active component, an auxiliary agent and a porous carrier, wherein the auxiliary agent and the active component are wrapped by the porous carrier to form a core-shell structure, the active component is palladium, the auxiliary agent is one or more of cerium oxide, copper oxide, nickel oxide and iron oxide, and the porous carrier is a ZSM-5 molecular sieve, and is characterized in that the preparation method of the catalyst comprises the following steps:
step 1: adding a first alkali compound into first part of water, stirring, and adding a mixture of water and alkali compound in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion A;
step 2: adding a proper amount of hydrochloric acid and a second part of water into the palladium salt and the auxiliary salt, stirring, and adding the palladium salt and the auxiliary salt in a volume ratio of 1: continuously and uniformly stirring the CO-520 and the cyclohexane in the step (2-3) to form a microemulsion B;
and step 3: mixing the microemulsion A and the microemulsion B, adding a proper amount of a second alkali compound after stirring for a period of time, slowly adding an organic amine template after continuously stirring for a period of time, and uniformly stirring to obtain a microemulsion C;
and 4, step 4: adding a certain amount of aluminum source compound into the microemulsion C under the stirring action, slowly adding a proper amount of silicon source compound after the aluminum source is uniformly dispersed, continuously stirring until the aluminum source is in a white emulsion state, then transferring the white emulsion state into a hydrothermal synthesis kettle, and crystallizing for a period of time under the hydrothermal synthesis condition;
and 5: carrying out solid-liquid separation, washing, drying and roasting on the crystallized material;
step 6: reducing the roasted material to obtain a catalyst;
in the raw materials, the aluminum source compound and the silicon source compound are SiO2And Al2O3Meter, SiO2And Al2O3The molar ratio of (80-100) to (1), organic amine template and Al2O3The molar ratio of (4-8): 1, second base compound with Al2O3The molar ratio of (4-8): 1 total water content and Al2O3The molar ratio of (2000-4000): 1.
2. the palladium catalyst for removing trace sulfides from benzene as claimed in claim 1, wherein the mass ratio of the active component in the catalyst is 0.5-3%, the mass ratio of the auxiliary in the catalyst is 1-5%, and the balance is porous carrier.
3. The palladium catalyst for removing trace sulfide from benzene as claimed in claim 1, wherein cerium oxide is a first promoter, one or more of the remaining oxides is a second promoter, and the mass ratio of the first promoter to the second promoter is 1: 1.
4. the palladium catalyst for removing trace sulfide from benzene as claimed in any one of claims 1 to 3, wherein the first alkali compound in step 1 is sodium hydroxide, potassium hydroxide or concentrated ammonia.
5. The palladium catalyst for removing trace sulfide from benzene as claimed in any one of claims 1 to 3, wherein the palladium salt in step 2 is palladium chloride or palladium nitrate, and the auxiliary salt is one or more of nitrate, sulfate, acetate and chloride.
6. The palladium catalyst for removing trace sulfide from benzene as claimed in any one of claims 1 to 3, wherein the second alkali compound in step 3 is sodium hydroxide, potassium hydroxide or concentrated ammonia water, and the organic amine template is tetrapropylammonium hydroxide.
7. The palladium catalyst for removing trace sulfide from benzene as claimed in any one of claims 1 to 3, wherein the hydrothermal synthesis conditions in step 4 is 150 to 170 ℃ for crystallization for 48 to 72 hours.
8. The palladium catalyst for removing trace sulfide in benzene as claimed in any one of claims 1 to 3, wherein the drying in step 5 is carried out by heating to 50-100 ℃ at a rate of 1-15 ℃/min for 1-5 h; when in roasting, the temperature is raised from room temperature to 150-700 ℃ at the speed of 1-15 ℃/min for 2-10 h.
9. The palladium catalyst for removing trace sulfide from benzene as claimed in any one of claims 1 to 3, wherein the reduction in step 6 comprises gas phase reduction or liquid phase reduction; introducing hydrogen, carbon monoxide or ethylene during gas phase reduction at 80-200 deg.C for 1-10h, at 120 deg.C and 160 deg.C, and with space velocity not exceeding 6h-1(ii) a The pH value is controlled to be 8-12 during liquid phase reduction, and sodium borohydride, hydrazine hydrate, aldehydes, carboxylic acids or olefins are adopted.
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