CN-118105962-B - Method and device for preparing alumina carrier and catalyst with reduction function by using carbon-containing mixed gas

Abstract

The invention provides a method and a device for preparing an alumina carrier with a reduction function and a catalyst by using a carbon-containing mixed gas. The preparation method of the alumina carrier with the reduction function and the catalyst comprises the following steps of (1) placing an alumina precursor in a reactor, performing contact reaction on carbon-containing mixed gas and the alumina precursor at 400-600 ℃, and controlling gas flow and reaction time to obtain the alumina carrier with the reduction function. (2) And loading the metal by an impregnation method, and reducing the metal in situ in the loading process to obtain the noble metal catalyst. Meanwhile, a device for preparing the alumina carrier with the reduction function by using the carbon-containing mixed gas is provided. The prepared alumina carrier with the reduction function can accurately control the in-situ reduction of noble metal on the carrier in the process of impregnating and loading the noble metal, and avoid the traditional unit operation process of high-energy consumption and dangerous loading-before-hydrogenation reduction.

Inventors

• FENG JUNTING
• DUAN XUE
• ZHANG YIJUN
• WANG QIAN
• LI DIANQING

Assignees

• 衢州资源化工创新研究院
• 北京化工大学

Dates

Publication Date

20260505

Application Date

20240227

Claims (2)

1. 1. A method for preparing a catalyst with a reduction function alumina carrier by using a carbon-containing mixed gas, which is characterized by comprising the following steps: placing an alumina precursor in a reactor, sealing, firstly, introducing a protective gas into the reactor through a deoxidizing device, then introducing a carbon-containing gas M into the reactor after deoxidizing through the deoxidizing device, controlling the flow rate of the carbon-containing gas M and the protective gas through a mass flowmeter to adjust the proportion of reaction gas, introducing the reaction gas into the reactor for 8-15min, heating the reactor by adopting a programmed heating method, wherein the heating rate is 2-15 ℃ per min, the reaction temperature is 400-600 ℃, the reaction time is 1-10h, the flow rate of the reaction gas is 10-100 mL per min, cooling to room temperature after the reaction is finished, rapidly taking out a sample, and vacuum packaging for standby to obtain an alumina carrier with reducibility, wherein the crystal form of the alumina carrier is gamma type; the reaction gas consists of carbon-containing gas M and protective gas, wherein the volume content of the carbon-containing gas M is 5-60%, and the balance is the protective gas; The shielding gas is inert gas, nitrogen or argon; the deoxidizing device is a drying pipe added with 401 manganese deoxidizing agent; the carbon-containing gas M is any one or more of CH 4 、C 2 H 2 、CO、C 2 H 4 、C 2 H 6 ; The alumina precursor is any one of spherical boehmite, strip boehmite, powdery pseudo-boehmite and powdery aluminum hydroxide; In the reaction process of the step A, carbon-containing gas molecules in the carbon-containing mixed gas are adsorbed on the surface of the alumina precursor to induce the Al-O bonding structure to change, and surface hydroxyl groups of the alumina precursor are activated to generate active intermediates H, one part of the active intermediates H are removed, and the other part of the active intermediates migrate on the surface and are stabilized on the surface again to form the Al-O-H bonding structure with reducibility; b, adding the alumina carrier with reducibility obtained in the step A into an equal volume of precious metal impregnating solution, wherein the concentration of the precious metal solution is determined according to the content of precious metal required by a final product; For the formed alumina carrier, uniformly mixing the formed alumina carrier with the noble metal solution, and putting the mixture into an oven to be dried for 6-36 hours at the temperature of 20-90 ℃ to obtain the alumina carrier loaded with noble metal elements; Aiming at the powdery alumina carrier, placing the mixture of the powdery alumina carrier and the noble metal solution in a water bath kettle, adding a magnet to stir at the rotating speed of 100-1000 revolutions per minute, and placing the mixture into an oven to be dried when the solution is quickly dried to obtain the alumina carrier loaded with noble metal elements; in the impregnation process, metal cations gradually get close to the surface of the carrier, migrate to the vicinity of Al-O-H bonds due to charge interaction, and the Al-O-H structure gives electrons to the metal cations, so that the metal cations are reduced to form metal atoms, the reduced noble metal catalyst is obtained, and the synchronous completion of loading and reduction is realized.
2. 2. The method of claim 1, wherein the temperature programming process of the step A is carried out for 2-6 hours, and the flow rate of the reaction gas is 10-60 mL/min; the volume content of the carbon-containing gas M in the reaction gas is 10-40%, and the balance is the shielding gas; The carbon-containing gas M is any one, two or three of CH 4 、C 2 H 2 、CO、C 2 H 4 、C 2 H 6 ; the alumina precursor is powdery aluminum hydroxide or powdery pseudo-boehmite.

Description

Method and device for preparing alumina carrier and catalyst with reduction function by using carbon-containing mixed gas Technical Field The invention relates to the field of catalyst preparation, in particular to preparation of an alumina carrier with a reduction function and a simple preparation technology of a noble metal catalyst. Background The catalyst is the "heart" and basis for the catalytic reaction. Compared with non-noble metal catalysts, noble metal catalysts are valued for their excellent activity, selectivity and stability, and are widely used for reactions such as hydrogenation, dehydrogenation, oxidation, reduction, isomerization, aromatization, cracking, synthesis and the like, and play a very important role in fields such as chemical industry, petroleum refining, petrochemistry, medicine, environmental protection, new energy sources and the like. Noble metal catalysts generally consist of a noble metal active component, an auxiliary agent and a carrier, and common methods for supporting noble metals are a sol-gel fixation method and an impregnation method. However, both methods have some disadvantages, and the sol-gel immobilization method is relatively complex, involves many steps and chemical reactions, and requires strict control of temperature, pH, reaction time, etc. In the sol fixing process, the metal particles usually use organic macromolecules as a protective agent, and because strong interaction is not formed between the metal and the carrier, loss of active components is easily caused in the reaction process, and the stability and purity of the catalyst are influenced by the residual protective agent. The impregnation method is simple and easy to implement, high-efficiency and convenient, but is influenced by solvation effect and active component cluster effect in the impregnation process, so that the active component is not easy to be highly dispersed, thereby causing large consumption of the active component and low metal utilization rate. At the same time, high temperature reduction of the metal is required after impregnation, which results in agglomeration of the supported metal. The reduction process typically uses hydrogenation reduction, which presents a certain risk. After the noble metal-supported activated carbon catalyst was obtained as in patent CN 109261145A, it was further reduced under a hydrogen atmosphere at 160 ℃ for 10 hours. As in patent CN 104399537A, a Pd/Al 2O3 catalyst was obtained, which also required reduction under a hydrogen atmosphere at 200℃for 3 to 50 hours. At present, searching for a simple, safe and energy-saving technology for preparing an excellent noble metal catalyst is still one research direction of the catalyst. Therefore, the preparation of the noble metal catalyst without adding any reducing agent has great significance, so that the dangerous hydrogenation reduction process can be avoided, the agglomeration of the supported metal is reduced, and the quality of the catalyst is improved. Disclosure of Invention The invention aims to provide a method and equipment for preparing an alumina carrier and a catalyst with a reduction function by treating an alumina precursor by using a carbon-containing mixed gas. The method for preparing the alumina carrier and the catalyst with the reduction function by using the carbon-containing mixed gas is characterized in that the carbon-containing mixed gas reacts with an alumina precursor, the carbon-containing mixed gas can be adsorbed on the surface of the alumina precursor, al-O bonding structure in the alumina carrier is induced to change, and hydroxyl groups are dissociated and activated on the surface to form an active intermediate H, wherein a part of the active intermediate H is removed, and the other part of the active intermediate is migrated on the surface and finally re-stabilized on the surface to form the alumina carrier with the reduction Al-O-H bonding structure. The alumina carrier is loaded with noble metal salt solution by an impregnation method, and the Al-O-H structure on the surface of the carrier can reduce noble metal on the carrier in situ in the loading process, so that the small size and the high dispersion of metal particles are effectively maintained, and the synchronous completion of loading and reduction is realized. The method for preparing the alumina carrier with the reduction function and the catalyst by using the carbon-containing mixed gas comprises the following specific steps: Placing an alumina precursor in a reactor, sealing, introducing a protective gas into the reactor through a deoxidizing device, deoxidizing M gas through the deoxidizing device, introducing the deoxidized M gas into the reactor, controlling the flow rate of the M gas and the flow rate of the protective gas through a mass flowmeter to adjust the proportion of reaction gas, introducing the reaction gas into the reactor for 8-15min, heating the reactor by adopting a programmed heating method,