阅读说明：本技术 一种氧化硅负载型过渡金属失活催化剂的再生方法 (Regeneration method of silica-supported transition metal deactivated catalyst ) 是由 刘庆 陈亚琪 于 2021-06-10 设计创作，主要内容包括：本发明提供一种氧化硅负载型过渡金属失活催化剂的再生方法,实现催化剂的重复循环利用,降低催化剂使用成本。氧化硅负载型金属催化剂,一般具有较弱的金属-载体相互作用,在高温下金属易烧结,导致催化活性降低甚至失活。本发明对烧结失活的氧化硅负载型过渡金属(铁、钴、镍)催化剂,进行酸溶处理后,原位加入一定量的碱性物质和氟系氧化硅刻蚀剂,在温和条件下水热反应制备出页硅酸盐,还原后实现氧化硅负载型过渡金属(铁、钴、镍)催化剂的再生。本发明无需特殊反应器,操作简单,再生条件温和,可实现SiO-(2)载体和过渡金属的同时回收,无需补充SiO-(2)和过渡金属前驱体,添加剂成本低廉,对溶液的酸碱性要求低,环境友好,适合批量化生产。(The invention provides a regeneration method of a silica-supported transition metal deactivated catalyst, which realizes the repeated cyclic utilization of the catalyst and reduces the use cost of the catalyst. Silica supported metal catalysts generally have weak metal-support interaction, and metal is easy to sinter at high temperature, so that the catalytic activity is reduced and even the catalyst is inactivated. The invention carries out acid dissolution treatment on the silicon oxide load type transition metal (iron, cobalt and nickel) catalyst which is inactivated by sintering, adds a certain amount of alkaline substance and fluorine silicon oxide etching agent in situ, prepares phyllosilicate by hydrothermal reaction under mild conditions, and realizes regeneration of the silicon oxide load type transition metal (iron, cobalt and nickel) catalyst after reduction. The invention does not need a special reactor, has simple operation and mild regeneration condition, and can realize SiO 2 Simultaneous recovery of carrier and transition metal without SiO supplementation 2 And the transition metal precursor, the additive has low cost, low requirement on the acidity and alkalinity of the solution, and environmental protection, and is suitable for batch production.)

1. A regeneration method of a silica supported transition metal deactivated catalyst is characterized in that the silica supported transition metal deactivated by sintering catalyst is added into acid solution with certain concentration to dissolve metal, then proper amount of alkaline substance and fluorine-based silica etching agent are added in situ, mixed evenly and transferred to a hydrothermal kettle at 40-140 DEG^oC, carrying out hydrothermal reaction, cooling, separating, washing, drying and roasting to obtain phyllosilicate H₂Reducing under the atmosphere to obtain the regenerated silicon oxide supported transition metal catalyst.

2. The method for regenerating a deactivated catalyst of silica supported transition metal according to claim 1, wherein the deactivated catalyst of silica supported transition metal is added to an acid solution with a certain concentration, stirred at room temperature for 6-12 h to completely dissolve the metal, added with an alkaline substance and a fluorine-based silica etching agent, stirred for 5min, sonicated for 10min, transferred to a hydrothermal reactor at 40-140 deg.C^oC, heating the mixture for 6 to 24 hours in water, and cooling the mixture to room temperature; washing with deionized water and anhydrous ethanol for several times at 40-80 deg.C^oC, after vacuum drying in an oven, 400 ℃ in air atmosphere^oCalcining C for 2H to obtain phyllosilicate in H₂Reducing under atmosphere to obtainTo a regenerated silica supported transition metal catalyst.

3. The method of claim 2, wherein the deactivated transition metal is sintered and comprises a mixture of one or more of iron, cobalt, and nickel.

4. The method for regenerating a silica-supported transition metal deactivated catalyst according to claim 3, wherein the silica-supported transition metal deactivated catalyst is sintered in a certain concentration of acid solution, the kind of acid includes nitric acid, hydrochloric acid, acetic acid, etc., and the molar ratio of the acid to the metal on the catalyst is 3:1 to 10: 1.

5. The method for regenerating a silica-supported transition metal deactivated catalyst according to claim 4, wherein the basic substance comprises one or more of urea, hexamethylenetetramine, ammonia, sodium hydroxide and potassium hydroxide in a molar ratio of 7:1 to 15: 1.

6. The method of claim 5, wherein the fluorine-based silicon oxide etchant comprises a mixture of one or more of ammonium fluoride, ammonium bifluoride, and ammonium hexafluorosilicate, and the molar ratio of the fluorine-based silicon oxide etchant to silicon oxide is 3:1 to 6: 1.

7. The method for regenerating a silica-supported transition metal deactivated catalyst according to claim 6, wherein the different sintered deactivated silica-supported transition metal catalysts are prepared as phyllosilicates by the regeneration method of the present invention in H₂600-800 materials under atmosphere^oReducing the C for 1h to obtain the silicon oxide supported transition metal (iron, cobalt and nickel) catalyst.

8. A deactivated silica-supported transition metal catalyst regenerated by the method of any one of claims 1 to 7.

Technical Field

The invention belongs to the technical field of catalyst preparation and regeneration, and particularly relates to a regeneration method of a silica-supported transition metal deactivated catalyst.

Background

Silica supported transition metal catalysts (e.g., Ni/SiO)₂，Co/SiO₂And Fe/SiO₂) Tend to have a high specific surface area, excellent catalytic activity and high temperature stability are applied to many catalytic fields. However, catalyst deactivation is a problem that almost all industrial catalytic processes have to face. When the silica-supported transition metal catalyst is used for a long time in high-temperature reactions (such as reforming, catalytic combustion, methanation and the like), certain phenomena of metal sintering and agglomeration, carbon deposition and the like inevitably occur, and the activity is gradually reduced and even inactivated. The deactivated catalyst is often improved by replacing the catalyst with a new one, and therefore, the regeneration of the deactivated catalyst is a problem to be solved.

The traditional method for regenerating the carbon deposition deactivation catalyst is to burn off carbon deposition (CN1233617C, CN109647436A) under specific oxidizing atmosphere and temperature; for the metal sintering deactivated catalyst, a series of complex processes such as acid-base separation, purification and the like are mostly adopted to only recover the metal components in the catalyst, and the catalyst carrier is abandoned, so that the cost is high, the pollution is great, and the reutilization is difficult. CN109647436A discloses a regeneration method of transition metal deactivated catalyst, which uses different atmospheres (oxygen-containing gas, protective gas, reducing gas) to perform calcination treatment at different stages to achieve the regeneration effect of carbon deposition or sintering deactivated catalyst, but is only applicable to catalyst using alumina as carrier, not applicable to silica supported catalyst.

The phyllosilicate has excellent physical and chemical properties, is widely applied to battery materials, magnetic substances, catalyst carriers and the like, has the characteristics of high specific surface, high stability and surface permeability, and can contain a large amount of guest molecules or large-sized guests in the staggered and stacked part. Among them, phyllosilicate materials have made important progress in many technical fields such as catalysts, batteries, photoelectric materials, and magnetic science. The silicon oxide supported transition metal (iron, cobalt and nickel) catalyst can be obtained after reduction of phyllosilicate (iron, cobalt and nickel), and has the characteristics of high specific surface area, strong catalytic activity and high catalyst loading capacity. The sintering deactivated silicon oxide supported transition metal (iron, cobalt and nickel) catalyst is pretreated to a certain degree, and the regeneration is realized through phyllosilicate, so that the recycling of the catalyst can be realized, the interaction between the metal and the carrier of the catalyst is improved, the stability is enhanced, and the activity and the stability of the catalyst can be improved to a certain degree.

In view of the above, there is a growing interest in the problem of regeneration of deactivated catalysts. However, most regeneration processes have the problems of complex operation, low utilization rate, high cost, serious pollution and the like. Therefore, a simple and easy regeneration method which is simple and convenient to operate, low in cost and capable of fully utilizing the characteristics of the components of the catalyst needs to be explored.

Disclosure of Invention

In order to overcome the problems in the prior art, the invention aims to provide a regeneration method of a silica-supported transition metal deactivated catalyst, which has the advantages of mild preparation conditions, simple operation process, less loss and low pollution. The activity of the regenerated catalyst is basically kept unchanged or even the activity of the regenerated catalyst is improved in the methanation high-temperature reaction.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for regenerating the deactivated catalyst of silicon oxide supported transition metal includes such steps as reducing the deactivated catalyst, putting it in a certain acid solution, dissolving all metals, adding alkaline substance, adding fluoric silicon oxide as etching agent, mixing, hydrothermal reaction at 40-140 deg.C, cooling, separating, washing, drying, calcining to obtain regenerated phyllosilicate, and reducing.

The method specifically comprises the following steps:

adding the deactivated silicon oxide supported transition metal catalyst into an acid solution with a certain concentration, stirring for 6-12 h at room temperature to completely dissolve metals, adding a certain amount of alkaline substances, adding a fluorine silicon oxide etching agent, stirring for 5min, performing ultrasonic treatment for 10min, transferring to a hydrothermal kettle, and performing hydrothermal treatment at 40-140 ℃ for 6-24 h. And cooling to room temperature, washing with deionized water and absolute ethyl alcohol for several times respectively, drying in a drying oven at 40-80 ℃ in vacuum, roasting at 400 ℃ for 2h in air atmosphere to prepare regenerated phyllosilicate, and reducing to obtain the silicon oxide supported transition metal catalyst.

The deactivated catalyst carrier is silicon oxide.

The acid solution can be one or a mixture of more acids such as acetic acid, hydrochloric acid, nitric acid and the like, and the molar ratio of the acid to the metal is 3: 1-10: 1.

The alkaline substance comprises one or more of urea, hexamethylenetetramine, ammonia water, sodium hydroxide and potassium hydroxide, and the molar ratio of the alkaline substance to the transition metal is 7: 1-15: 1.

The fluorine-based silicon oxide etchant comprises one or a mixture of ammonium fluoride, ammonium bifluoride and ammonium hexafluorosilicate, and the molar ratio of the fluorine-based silicon oxide etchant to silicon oxide is 3: 1-6: 1.

The deactivated catalyst is silica supported transition metal catalyst, and the active component is one or several of Ni, Co and Fe.

The fluorine-based silicon oxide etchant is very critical to the regeneration preparation process and has the following bright points. Firstly, in the regeneration preparation process of the catalyst, the fluorine-based silicon oxide etching agent plays an etching role toDeactivated catalyst SiO₂The carrier reacts to generate orthosilicic acid, and SiO on the surface of the carrier is etched₂So that more new surfaces are exposed, more surface silicon hydroxyl groups are possessed, and the generated free orthosilicic acid is beneficial to the synthesis of the phyllosilicate catalyst in the next step. And secondly, the fluorine ions and the metal M ions can form a complex, so that the M ions can be slowly released to react, the generation of a large amount of metal hydroxide is avoided, and the metal hydroxide is ensured to be only used as an intermediate and not a byproduct. In the hydrothermal process, metal hydroxides react with orthosilicic acid to form phyllosilicates. The formation step of nickel phyllosilicate is disclosed in CN 112221503A.

Compared with the traditional transition metal deactivated catalyst regeneration method, the invention has the advantages as follows.

1. The method fully utilizes the characteristics of the original component materials of the catalyst, does not need to supplement transition metal (iron, cobalt and nickel) based precursors and silicon oxide carriers again, recycles and saves material cost.

2. The method is simple to operate, time-saving and labor-saving, only a small amount of acid, fluorine silicon oxide etching agent and alkaline substance are consumed as treating agents, the strict requirements of an atmosphere regeneration method on equipment are eliminated, only simple and mild hydrothermal treatment is needed, and the cost is greatly reduced.

3. The regenerated sample is phyllosilicate, and the silicon oxide supported metal catalyst is obtained after reduction, and the phyllosilicate has strong metal-carrier interaction, so that the catalytic activity and the stability are improved.

4. The invention can regenerate the silicon oxide load type transition metal catalyst for a plurality of times, saves the cost of the catalyst, and reduces the fussy operation steps and the environmental pollution caused by the inactivation and abandonment of the catalyst.

Drawings

FIG. 1 is an XRD pattern of a nickel phyllosilicate catalyst obtained by regeneration in examples 1 and 2 of the present invention, and a nickel phyllosilicate catalyst prepared by CN112221503A in comparative example 1 and NiO/SiO catalyst prepared by impregnation in comparative example 2₂A catalyst.

FIG. 2 is an SEM image of a nickel phyllosilicate catalyst obtained by regeneration in example 1 of the present invention.

Fig. 3 is an SEM image of the nickel phyllosilicate catalyst prepared by CN112221503A in comparative example 1.

FIG. 4 shows Ni/SiO reaction obtained by reduction of regenerated nickel phyllosilicate in example 1 of the present invention₂TEM images of the catalyst.

FIG. 5 shows the reduced Ni/SiO solid prepared by CN112221503A in comparative example 1 of the present invention₂TEM images of the catalyst.

FIG. 6 is an SEM image of a nickel phyllosilicate catalyst obtained by regeneration in example 2 of the present invention.

FIG. 7 is an SEM photograph of a nickel oxide/silica catalyst prepared by a conventional impregnation method in comparative example 2 FIG. 8 is a SEM photograph of Ni/SiO solid obtained by reduction of nickel phyllosilicate after regeneration in example 2 of the present invention₂TEM images of the catalyst.

FIG. 9 is a reduced Ni/SiO solid phase prepared by conventional impregnation method according to comparative example 2 of the present invention₂TEM images of the catalyst.

Detailed Description

The technical solution of the present invention is further illustrated by the following specific examples, but the present invention is not limited to the following examples.

Example 1:

deactivated Ni/SiO prepared in comparative example 1₂Adding the catalyst into a nitric acid solution (the molar ratio of nitric acid to metallic nickel is 5:1), stirring at room temperature for 12h to completely dissolve the metallic nickel, and adding urea according to the molar ratio of urea to nickel of 10: 1. Then ammonium fluoride (ammonium fluoride to nickel molar ratio 5:1) was added, stirred for 5min, sonicated for 10min, and then transferred to a hydrothermal kettle for hydrothermal 6h at 140 ℃. And cooling to room temperature, washing with deionized water and absolute ethyl alcohol for several times respectively, drying in a 60 ℃ drying oven in vacuum, and roasting at 400 ℃ for 2h in air atmosphere to obtain the regenerated nickel phyllosilicate catalyst. Then at H₂Reducing for 1h at 700 ℃ in the atmosphere to obtain Ni/SiO₂Catalyst for CO₂And (4) carrying out methanation reaction.

The XRD pattern of the nickel phyllosilicate catalyst prepared in example 1 is shown in fig. 1. It can be clearly seen that the nickel phyllosilicate catalyst regenerated in example 1 has a XRD pattern similar to that obtained in comparative example 1, with 5 strong diffraction peaks belonging to the nickel phyllosilicate, corresponding to 19.5, 24.4, 34.1, 36.6 and 60.5 deg., respectively.

SEM image of regenerated nickel phyllosilicate catalyst prepared in example 1 referring to fig. 2, it can be seen that this sample has the same morphology and structure as the nickel phyllosilicate of comparative example 1 (fig. 3).

Example 1 reduction of the Ni/SiO obtained after regeneration₂TEM image of catalyst referring to FIG. 4, it can be seen that nickel particles are highly dispersed on the nanosheets, in contrast to the reduced Ni/SiO phase prepared by CN112221503A of comparative example 1₂TEM images of the catalyst were similar (fig. 5).

Example 2

Deactivated Ni/SiO prepared in comparative example 2₂Adding the catalyst into a hydrochloric acid solution (the molar ratio of hydrochloric acid to metallic nickel is 10:1), stirring for 10 hours at room temperature to completely dissolve the metallic nickel, and adding hexamethylenetetramine according to the molar ratio of hexamethylenetetramine to nickel of 8: 1. Then adding ammonium fluoride (the molar ratio of the ammonium fluoride to the nickel is 6:1), stirring for 5min, carrying out ultrasonic treatment for 10min, and then transferring to a hydrothermal kettle to carry out hydrothermal treatment at 100 ℃ for 12 h. And cooling to room temperature, washing with deionized water and absolute ethyl alcohol for several times respectively, drying in a drying oven at the temperature of 80 ℃ in vacuum, and roasting at the temperature of 400 ℃ for 2 hours in an air atmosphere to obtain the regenerated nickel phyllosilicate catalyst. The XRD pattern is shown in figure 1. Then at H₂Reducing for 1h at 600 ℃ in the atmosphere to obtain Ni/SiO₂Catalyst for CO₂And (4) carrying out methanation reaction.

SEM image of regenerated nickel phyllosilicate catalyst prepared in example 2 referring to FIG. 6, it can be seen that NiO/SiO prepared by the conventional impregnation method in this sample and ratio 2₂The catalyst (fig. 7) has a distinct morphology and structure, and the regenerated nickel phyllosilicate catalyst in example 2 has a typical lamellar structure.

Example 2 reduction of the Ni/SiO obtained after regeneration₂TEM image of catalyst in FIG. 8, it can be seen that fine nickel particles are highly dispersed on the nanosheets as compared to Ni/SiO prepared in comparative example 2₂The TEM images (fig. 9) of the catalysts are clearly different, which is the reason for the improved activity of the catalyst after regeneration.

Example 3

C to be deactivated by sinteringo-Fe/SiO₂Adding the catalyst into an acetic acid solution (the molar ratio of acetic acid to metal (Co + Fe) is 3:1), stirring at room temperature for 6h to completely dissolve metal cobalt and iron, and adding an alkaline mixture according to the molar ratio of alkaline substances (ammonia water, sodium hydroxide and potassium hydroxide, the molar ratio is 1:1:1) to nickel 9: 1. Then, according to the molar ratio of the mixture of ammonium bifluoride and ammonium hexafluorosilicate (1: 1) to nickel being 3:1, stirring is carried out for 5min, ultrasonic treatment is carried out for 10min, and then the mixture is transferred to a hydrothermal kettle to be hydrothermal for 24h at 40 ℃. Cooling to room temperature, washing with deionized water and anhydrous ethanol for several times, vacuum drying in 40 deg.C oven, roasting at 400 deg.C for 2 hr in air atmosphere to obtain regenerated cobalt iron phyllosilicate, and calcining in H₂Reducing for 1h at 800 ℃ in the atmosphere to obtain Co-Fe/SiO₂Catalyst for CO₂And (4) carrying out methanation reaction.

Comparative example 1

Amorphous silicon oxide prepared from silicon-containing biomass waste rice hulls, ammonium fluoride, urea and nickel nitrate are placed in 50mL of deionized water according to the molar ratio of 4:5:6:1, stirred for 5min, subjected to ultrasonic treatment for 10min, and then transferred to hydrothermal treatment at 120 ℃ for hydrothermal treatment for 12 h. After cooling to room temperature, washing with deionized water and absolute ethyl alcohol respectively for several times, drying in a drying oven at 80 ℃ in vacuum, and then roasting in a muffle furnace at 400 ℃ for 2h to prepare the nickel phyllosilicate catalyst, wherein the XRD pattern of the nickel phyllosilicate catalyst is shown in figure 1.

By comparing the regenerated nickel phyllosilicate catalyst SEM (fig. 2), it can be seen that the regenerated nickel phyllosilicate catalyst is in the same morphology as the nickel phyllosilicate catalyst SEM (fig. 3) in comparative example 1. And the catalyst has a TEM (FIG. 5) in which the dispersibility of the fine Ni particles is similar to that of the regenerated Ni/SiO prepared in example 1₂Catalyst TEM (fig. 6).

Comparative example 2

Dropwise adding nickel nitrate aqueous solution onto a silicon oxide carrier (nickel oxide loading is 30%) by an isometric impregnation method, standing at room temperature for 24h, then drying in a 60 ℃ oven in vacuum, and roasting in a 400 ℃ muffle furnace for 2h to obtain the supported nickel-based catalyst (NiO/SiO)₂) The XRD pattern is shown in figure 1, the SEM image is shown in figure 6, and the TEM image is shown in figure 8.

Comparative example 2NiO/SiO₂The XRD pattern of the catalyst is shown in figure 1. It can be clearly seen that the XRD pattern of the impregnated supported nickel-based catalyst has 4 strong diffraction peaks attributed to nickel oxide, corresponding to 37.2, 43.2, 62.9 and 75.5 °, respectively.

From the SEM (FIG. 7) of the supported nickel oxide/silica catalyst prepared in comparative example 2, it can be seen that significant adhesion of nickel particles to SiO, which is a support, was observed on the surface thereof₂Of (2) is provided. Compared with the regenerated nickel phyllosilicate catalyst (figure 6), the surface of the catalyst is changed from small particles originally loaded on the surface of the carrier into a lamellar structure with the nickel phyllosilicate catalyst, the appearance is obviously changed, and the catalytic activity is obviously improved. Referring to FIG. 9, it can be seen that the nickel particles are not uniformly distributed, and Ni/SiO prepared by regeneration of example 2₂The TEM (fig. 8) of the catalysts differed significantly.

Evaluation of catalyst Performance

Selection of CO₂The methanation reaction was a model reaction, and the catalysts prepared in examples 1 to 3 and comparative examples 1 and 2 were subjected to a catalyst performance test. 100mg of catalyst with 20-40 meshes is filled into a quartz reaction tube, and reaction feed gas H is introduced after hydrogen reduction₂:CO₂:N₂(volume flow ratio 12:3: 5). The reaction pressure is normal pressure, the mass space velocity is 60000 mL/h.g, and the reaction temperature is 425 ℃. The results are shown in tables 1 and 2.

Table 1 shows CO in methanation reactions for the catalysts of examples 1 to 3₂Conversion and CH₄Yield.

TABLE 2 Nickel-based catalyst prepared in comparative example for CO methanation reaction₂Conversion and CH₄Yield.

As mentioned above, the catalyst has similar or even better catalytic activity after regeneration of the silica-supported transition metal deactivated catalyst. But also can form a nickel phyllosilicate catalyst with strong metal-carrier interaction and higher stability. Compared with the traditional treatment process for regenerating the deactivated catalyst, the method has obvious advantages of saving cost, reducing the loss of catalyst materials and lightening the environmental pollution besides the preparation conditions.

Although the present invention has been described herein with reference to the illustrated embodiments thereof, which are intended to be preferred embodiments of the present invention, it is to be understood that the invention is not limited thereto, and that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure.