Catalysts embedded with metal oxides and methods of making and using same

Abstract

The present application relates to the field of catalyst, in particular to a kind of catalyst embedded metal oxide and preparation method and its application, the catalyst component includes silicon dioxide and metal oxide, structure is metal oxide embedded in silicon dioxide carrier;With the total weight of catalyst, the content of metal oxide in the catalyst is 15~70wt.%, and the content of silicon dioxide is 30~85wt.%;The dispersion of the catalyst is 10~30%.The present application method synthesis control parameter is less, and the obtained catalyst has the characteristics that surface hydrophilic-hydrophobic can be adjusted, metal content is high and metal particle is small and is uniformly distributed.

Description

Technical Field

[0001] This invention relates to the field of catalysts, and more specifically to a catalyst embedded in a metal oxide, its preparation method, and its application. Background Technology

[0002] Layered silicates are materials with a distinct layered structure and strong Si-O-Metal (Metal = Cu, Ni, Co, and Zn, etc.), and are widely used as precursors to prepare corresponding SiO2-supported transition metal catalysts. Copper-based catalysts supported on silica are widely used in the hydrodehydrogenation of organic compounds, while nickel-based catalysts supported on silica are widely used in the dry reforming of methane and carbon dioxide. Currently, there are numerous research reports on copper or nickel-based silicates; however, effectively reducing the particle size of the metal nanoparticles in the final catalyst while increasing the metal content remains a challenge.

[0003] Zhao Yue et al. (CN110813290A) disclosed a method for preparing a layered copper silicate composite. The method involves first mixing a copper salt with an ammonia-containing solution to obtain a copper-ammonium complex solution, then mixing the copper-ammonium complex solution with a soluble inorganic silicon solution to obtain a mixed solution, and finally removing the ammonia from the mixed solution. The ammonia-containing solution used includes any one or more of ammonia water, methylamine, and dimethylamine, and the soluble inorganic silicon solution includes any one or more of silica sol solution, sodium silicate solution, and potassium silicate.

[0004] Ren Zhiheng et al. (CN112517017A) disclosed a doped copper silicate nanotube catalyst, its preparation method, and its application. The catalyst was prepared by a hydrothermal method using copper nitrate, ammonium chloride, water, and silica sol as raw materials. The corresponding catalyst was used for the hydrogenation of methyl acetate to ethanol.

[0005] Chen Liangfeng et al. (CN112441922A) disclosed a catalyst for the oxidative coupling of CO to produce oxalate esters. The silicate support is prepared from copper or nickel salts, water, silica sol, and concentrated ammonia or urea as raw materials through heating and ammonia stripping steps. The copper and / or nickel content in the catalyst is 8-30% by weight.

[0006] Zhu Wancheng et al. (CN109019618B) disclosed a method for preparing hollow copper silicate microspheres. The corresponding catalyst was used as a Cu / SiO2 adsorbent for the adsorption of methylene blue, with a copper loading of approximately 44.4 wt.%. It was obtained through a one-step hydrothermal reaction using copper salts (CuCl2, CuSO4, Cu(NO3)2), soluble silicates (Na2SiO3, K2SiO3), and ammonium salts (NH4Cl, NH3·H2O, (NH4)2SO4, ethylenediamine).

[0007] Fang Yuan et al. (Journal of Catalysis, 2022, 407, 45-53) reported K + The formation of an induced granular dense copper silicate precursor was studied. This precursor was prepared via hydrothermal synthesis using Cu(NO3)2·3H2O, KCl, NH3·H2O, and nano-sized SiO2 as raw materials. After calcination and hydrogen reduction, the catalyst exhibited excellent activity in the catalytic reaction of dimethyl oxalate to ethylene glycol. The copper nanoparticles in the catalyst had a particle size of approximately 4.3 nm and a copper mass percentage of 71 wt.%.

[0008] In 2018, Xiao Fengshou et al. (ACS Catal. 2018, 8, 474-481) increased the hydrophilicity of the Pd@S-1 catalyst by adding diethoxydimethylsilane. Compared with the Pd@S-1 catalyst with strong hydrophobicity, the hydrophilic catalyst showed higher furfural hydrogenation conversion and furan selectivity in the furfural hydrogenation reaction.

[0009] In 2019, Yu Jihong et al. (J.Am.Chem.Soc.2019,141,3772-3776) used L-lysine as an additive and a two-step hydrothermal crystallization method to prepare ZSM-5 molecular sieve with a hierarchical porous structure.

[0010] In 2022, Wang Xinping et al. (Inorg. Chem. Front., 2022, 9, 2097-2103) used compounds containing guanidine functional groups as additives and employed a two-step hydrothermal crystallization method to prepare plate-like hierarchical porous MFI-type molecular sieves (S-1, ZSM-5 and TS-1).

[0011] Currently, the methods for preparing intercalated silica-based copper / nickel catalysts reported in the literature mainly involve ammonia stripping. These methods suffer from drawbacks such as numerous operational steps, easy decomposition of ammonia upon heating to produce irritating gases, and a large number of control parameters during synthesis. Furthermore, easily modulating the hydrophilicity / hydrophobicity of the catalyst remains a challenge, and few reports have been published on this method. More importantly, there are currently no reports on the preparation of intercalated silica-based metal catalysts by adding amino acids or guanidine-containing compounds. Summary of the Invention

[0012] The purpose of this invention is to overcome the problems of low metal content, large particle size of metal nanoparticles, complicated preparation methods, and many control parameters in existing silica-supported catalysts. This invention provides a catalyst embedded with metal oxides, its preparation method, and its application. The catalyst preparation method is simple, and the resulting catalyst not only has high metal content, high dispersion, high activity per unit amount of catalyst, and good anti-sintering properties, but also has the advantages of small and uniform particle size of metal nanoparticles and controllable strength of surface hydrophilicity and hydrophobicity.

[0013] To achieve the above objectives, the present invention provides a catalyst embedded with a metal oxide, wherein the catalyst comprises silicon dioxide and a metal oxide, and the structure is that the metal oxide is embedded in a silicon dioxide support; the metal oxide content of the catalyst is 15-70 wt.% and the silicon dioxide content is 30-85 wt.% based on the total weight of the catalyst; the catalyst dispersion is 10-30%.

[0014] A second aspect of the present invention provides a method for preparing the catalyst described herein, comprising the following steps:

[0015] (1) Thoroughly mix metal salt, alkali, silicon source, water, amino acid and / or compound containing guanidine functional group to obtain a mixed solution, and then place the mixed solution in a sealed container for reaction;

[0016] (2) The resulting reaction product is dried and calcined.

[0017] A third aspect of the present invention provides the application of the catalyst described herein in the dehydrogenation of cyclohexanol or in the dry reforming reaction of methane and carbon dioxide.

[0018] By adopting the above solution, the present invention has the following advantages:

[0019] The catalyst of this invention does not use ammonia water, requires less water, and has no specific order of addition when preparing the mother liquor. Therefore, it has lower washing requirements, less waste gas pollution, and fewer synthesis control parameters.

[0020] The catalyst preparation method of this invention is simple. The water in the reaction product is basically adsorbed on the solid surface, so there is no liquid water discharge. The product does not need to be washed, but only needs to be dried and roasted.

[0021] The catalyst of this invention has a high metal content and high dispersion of metal oxide nanoparticles, thus resulting in higher activity per unit amount of catalyst.

[0022] In this invention, the catalyst metal oxide nanoparticles are uniformly embedded in the topology of the catalyst support, resulting in lower mobility and better resistance to sintering.

[0023] The hydrophilic properties of the catalyst surface of this invention can be easily adjusted, thus facilitating researchers to design catalysts with better hydrodehydrogenation catalytic performance. Attached Figure Description

[0024] Figure 1 These are STEM images and elemental distribution diagrams of the copper-silicon catalyst obtained in Example 1;

[0025] Figure 2 This is the static contact angle of the copper-silicon catalyst obtained in Example 1;

[0026] Figure 3 This is the static contact angle of the copper-silicon catalyst obtained in Example 2;

[0027] Figure 4 This is the static contact angle of the copper-silicon catalyst obtained in Example 3;

[0028] Figure 5 Here is a STEM image of the nickel-silicon catalyst obtained in Example 8;

[0029] Figure 6 These are STEM images and elemental distribution diagrams of the nickel-silicon catalyst obtained in Example 8;

[0030] Figure 7 This is the static contact angle of the copper-silicon catalyst obtained in Comparative Example 1. Detailed Implementation

[0031] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0032] In one aspect, this invention provides a catalyst embedded with a metal oxide, the catalyst comprising silica and a metal oxide, wherein the metal oxide is embedded in a silica support; the metal oxide content of the catalyst is 15-70 wt.% and the silica content is 30-85 wt.% based on the total weight of the catalyst; the catalyst dispersion is 10-30%.

[0033] According to a particularly preferred embodiment of the present invention, the catalyst, based on the total weight of the catalyst, contains 25-45 wt.% metal oxides and 55-75 wt.% silica.

[0034] According to a particularly preferred embodiment of the present invention, the static contact angle of the catalyst with water is 20 to 80°, preferably 30 to 80°.

[0035] In this invention, the metal element can be any conventionally chosen element in the art, as long as it achieves the objective of the invention. According to a preferred embodiment of the invention, the metal element is selected from transition metals and / or Group IIA elements, specifically at least one of copper, nickel, manganese, cobalt, iron, zinc, and magnesium, more preferably at least one of copper, nickel, and manganese. By employing the aforementioned preferred embodiment, the performance of the catalyst in cyclohexanone dehydrogenation or methane dry reforming reactions can be further improved.

[0036] According to a particularly preferred embodiment of the present invention, the catalyst dispersion is 15-30%.

[0037] In this invention, metal dispersion is defined as the ratio between the number of metal atoms on the catalyst surface that CO gas molecules can contact and the total number of metal atoms in the catalyst.

[0038] According to a particularly preferred embodiment of the present invention, the average particle size of the metal oxide is 1-5 nm, preferably 1-2 nm.

[0039] The catalyst of this invention has a high metal content and high dispersion of metal oxide nanoparticles. The metal oxide nanoparticles are uniformly dispersed in the catalyst support, thus the catalyst has better resistance to sintering.

[0040] In this invention, any catalyst possessing the aforementioned characteristics can achieve the objective of this invention, and there are no special requirements for its preparation method. According to a particularly preferred embodiment of this invention, the preparation method of the catalyst includes:

[0041] (1) Thoroughly mix metal salt, alkali, silicon source, water, amino acid and / or compound containing guanidine functional group to obtain a mixed solution, and then place the mixed solution in a sealed container for reaction;

[0042] (2) The reaction products are dried and calcined.

[0043] According to a particularly preferred embodiment of the present invention, the method for preparing the catalyst includes:

[0044] (1) A mixed solution is obtained by mixing raw materials with a molar ratio of metal salt: base: SiO2: H2O: (amino acid and / or compound containing guanidine functional group) of (0.13-3.47): (0.1-0.5): 1: (10-100): (0.1-1.0);

[0045] (2) The above mixed solution is subjected to hydrothermal treatment;

[0046] (3) The reaction products are dried, granulated, calcined and tableted;

[0047] The conditions for the hydrothermal treatment include: a reaction temperature of 150–180°C and a reaction time of 1–7 days.

[0048] In the preparation method of the present invention, the hydrothermal treatment reaction product does not require washing, but only needs to be dried, granulated, calcined and tableted.

[0049] According to a preferred embodiment of the present invention, the hydrothermal reaction conditions include: first reacting at a temperature of 80-90°C for 0.5-3 days, and then raising the temperature to 150-180°C for 1-7 days; more preferably, the reaction is carried out at a dynamic rotation speed of 1-500 rpm.

[0050] According to a preferred embodiment of the present invention, the hydrothermal reaction is carried out in a homogeneous reactor (JXF6-200) at Yantai Songling Chemical Machinery Plant.

[0051] By adopting the aforementioned preferred scheme, the particle uniformity of the embedded silica-based metal catalyst in the catalyst can be further improved and the catalyst particle size can be reduced.

[0052] According to a particularly preferred embodiment of the invention, the pH of the mixed solution is greater than 7.

[0053] According to a particularly preferred embodiment of the present invention, in step (3), after the reaction product is calcined, an additive is added and the product is compressed into tablets, wherein the mass ratio of the reaction product to the additive is 1:(0.01 to 0.05).

[0054] According to a particularly preferred embodiment of the present invention, the additive is a mixture of graphite or magnesium stearate and water, preferably graphite or magnesium stearate:H2O = 1:(1-2).

[0055] By adopting the aforementioned preferred scheme, catalyst breakage during granulation can be further reduced, thereby improving the yield.

[0056] According to a particularly preferred embodiment of the present invention, the silicon source is selected from at least one of silica sol, silica fume, sodium silicate and tetraethyl orthosilicate.

[0057] According to a particularly preferred embodiment of the present invention, the alkali is a strong alkali selected from at least one of sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0058] According to a particularly preferred embodiment of the present invention, the metal is selected from at least one of copper, manganese, nickel, cobalt, iron, zinc and magnesium, preferably from at least one of copper, nickel and manganese.

[0059] According to a particularly preferred embodiment of the present invention, the metal salt is selected from at least one of metal nitrates, sulfates, hydrochlorides and carbonates, preferably metal nitrates or metal carbonates.

[0060] According to a particularly preferred embodiment of the present invention, the amino acid includes various types of amino acids, preferably α-amino acids and / or L-lysine, more preferably α-amino acids and L-lysine.

[0061] According to a particularly preferred embodiment of the present invention, the compound containing the guanidine functional group is selected from at least one of tetramethylguanidine, dodecylguanidine hydrochloride, and polyhexamethylene biguanide hydrochloride.

[0062] By adopting the aforementioned preferred scheme, the activity and mesopore volume of the catalyst can be further improved.

[0063] In this invention, the mixing conditions can be conventionally chosen in the art. According to a preferred embodiment of the invention, the mixing conditions include: stirring and mixing, a temperature of 5 to 50°C, and a time of 0.5 to 5 hours, preferably 2 to 3 hours.

[0064] According to a preferred embodiment of the present invention, the mixing conditions further include: using one or more means selected from magnetic field, electric field and infrared lamp irradiation to assist the mixing.

[0065] In this invention, the drying conditions can be conventionally selected in the art. According to a preferred embodiment of the invention, the drying conditions include: a temperature of 50 to 200°C, preferably 80 to 100°C, and a time that depends on the temperature, preferably 12 to 24 hours.

[0066] In this invention, the roasting conditions can be conventionally selected in the art. According to a preferred embodiment of the invention, the roasting conditions include: a temperature of 300-550°C, preferably 400-550°C; and a time that varies with the temperature, preferably 2-6 hours.

[0067] This invention provides the application of the catalyst described herein in the dehydrogenation of cyclohexanol or in the dry reforming reaction of methane and carbon dioxide.

[0068] According to a particularly preferred embodiment of the present invention, the catalyst is reduced with hydrogen-containing gas before use.

[0069] In this invention, the conditions for reduction treatment can be conventionally selected in the art. According to a preferred embodiment of this invention, the conditions for reduction treatment include: a reduction treatment temperature of 180-250°C, a reduction time of 8-24 h, and a hydrogen volume concentration of 20-100% in the hydrogen-containing gas.

[0070] The present invention will be further described below through specific embodiments, but the scope of the present invention is not limited to the scope covered by the embodiments. The testing methods, instruments, and reagents involved in the present invention are as follows:

[0071] Catalyst reduction treatment conditions: The reduction treatment temperature is 200℃, the time is 10h, and the volume concentration of hydrogen in the mixed gas is 80%.

[0072] The reaction, carried out under rotating conditions, was conducted in a homogeneous reaction vessel equipped with a rotating motor and a fixed position in the reactor at Yantai Songling Chemical Machinery Plant (JXF6-200).

[0073] Metal oxide particle size testing method: Elemental mapping in integral scanning mode is used to identify and characterize the metal oxides in the catalyst. Then, image software is used to measure the particle size of each particle individually. A total of 200 different particles are counted. Finally, a normal distribution model is used to fit the particle size of the catalyst to obtain the average particle size of the metal oxide particles in the catalyst.

[0074] The metal dispersion in the catalyst was determined by CO surface titration in a ChemBET Pulsar TPR / TPD system equipped with a TCD detector at 25°C. Before testing, the catalyst was reduced at 300°C in an H2 atmosphere, then cooled to 25°C, and finally purged with an N2 atmosphere. At the start of the test, a CO / N2 mixture (CO:N2 = 1:1) was introduced into the catalyst gas path using a metering loop. The CO content in the exhaust gas was measured, and this process was repeated multiple times until the CO peak intensity no longer changed, indicating that the catalyst had reached adsorption saturation. The molar amount of CO adsorbed by the catalyst (denoted as x) and the molar amount of metal in the packed catalyst (denoted as y) were calculated. The metal dispersion in the catalyst (denoted as z) is then z = x / y.

[0075] The hydrophilicity and hydrophobicity of the catalyst surface were characterized by measuring the static contact angle of the catalyst, and the test was performed on a static contact angle measuring instrument (model JY-82B).

[0076] Catalyst structure diagram: The morphology, internal structure, and elemental distribution of the samples were analyzed using a Philips-FEI Tecnai F30 transmission electron microscope equipped with EDX spectroscopy. The accelerating voltage of the electron microscope was 300 kV. Before testing, the samples were dispersed in ethanol and sonicated. A small amount of the sample dispersion was titrated onto a copper grid coated with a carbon film and dried under an infrared lamp.

[0077] Powder X-ray diffraction (XRD): The crystal structure of the samples was analyzed using a D-Max Rotaflex (Rigaku) ​​X-ray powder diffractometer under the following conditions: CuKα source. The tube voltage is 30kV, the tube current is 30mA, and the scanning speed is 5° / min.

[0078] Methods for determining the content of each element in the sample: The content of each element in the sample was determined using an ICPS-8100SHIMADZU inductively coupled plasma atomic emission spectrometer. A certain amount of solid catalyst sample was weighed and dissolved in a mixed solution of hydrofluoric acid and nitric acid. A quantitative amount of the solution was then diluted with a quantitative amount of deionized water. Using the same diluted mixed solution of hydrofluoric acid and nitric acid as a blank control, the content of different elements in the sample was determined by ICP-AES.

[0079] Evaluation of the catalytic activity of cyclohexanol dehydrogenation reaction: at specifications The experiment was conducted in a fixed-bed reactor with a feedstock cyclohexanol space velocity of 0.60 h⁻¹. -1 The reaction temperature was 230℃ and the catalyst loading was 50mL.

[0080] Catalytic activity evaluation of dry reforming reaction of methane and carbon dioxide: The reaction was carried out in a fixed-bed reactor with an inner diameter of 6 mm in a quartz tube. The reaction gas ratio was CO2:CH4 = 1:1, the gas hourly space velocity was 180,000 mL / g·h, and the reaction temperature was 800℃. 10 mg of catalyst (40-60 mesh) and 0.19 g of quartz sand (40-60 mesh) were weighed, mixed evenly, and placed in a quartz tube for activity evaluation.

[0081] Copper nitrate hexahydrate, Cu(NO3)2·6H2O, is produced by Aladdin Industries, with a purity of 99 wt.%.

[0082] Nickel nitrate hexahydrate, Ni(NO3)2·6H2O, is produced by Aladdin Industries, with a purity of 98 wt.%.

[0083] Sodium hydroxide was produced by Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of 99 wt.%.

[0084] The potassium hydroxide was produced by Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of 95 wt.%.

[0085] Tetramethylguanidine was produced by Sarex Chemicals (Shanghai) Co., Ltd., with a purity of 98 wt.%.

[0086] L-Lysine, C6H 14 N2O2, produced by Sinopharm Chemical Reagent Co., Ltd., with a content of 98 wt.%;

[0087] The alkaline sodium silica sol JN-25 was purchased from Qingdao Haiwan Fine Chemical Co., Ltd., batch number HY01101-825, with a silica content of 25 wt.% and a Na2O content of 0.3 wt.%.

[0088] Ethyl orthosilicate was produced by Tianjin Kemei Chemical Reagent Co., Ltd., with a purity of 98 wt.%.

[0089] Example 1

[0090] 12.60 g of Cu(NO3)2·6H2O and 0.81 g of NaOH were dissolved in 72 g of deionized water, and then mixed with 21.26 g of tetraethyl orthosilicate (98%) and 3.53 g of tetramethylguanidine. The molar ratio of the components in the mixed solution was Cu:NaOH:SiO2:H2O:tetramethylguanidine = 0.42:0.2:1:40:0.3. The mixture was stirred thoroughly at 25 °C for 2.5 hours. The resulting mixture was then transferred to a reaction vessel lined with polytetrafluoroethylene and reacted at 80 °C for 24 hours at 20 rpm, followed by a reaction at 170 °C for 1 day. The reaction product was dried overnight at 100 °C, granulated, calcined in air at 540 °C for 4 hours, and then 2 wt.% graphite additive and 3 wt.% deionized water were added. After thorough mixing, the mixture was pressed into tablets to obtain the catalyst.

[0091] The catalyst contains 33.1 wt.% CuO, 58.8 wt.% silica, 6.0 wt.% Na₂O, and 2.1 wt.% graphite. The average particle size of the CuO particles is 1.3 nm, and the dispersion of copper species in the catalyst is 25%. STEM images of the catalyst and elemental distribution diagrams of Cu and Si are shown below. Figure 1 As shown, the catalyst structure consists of copper oxide embedded in a silica support. The static contact angle of the catalyst is as follows. Figure 2 As shown, the static contact angle of the catalyst is 40.75°.

[0092] Example 2

[0093] 11.14 g of Cu(NO3)2·6H2O and 1.23 g of KOH were dissolved in 54 g of deionized water, and then mixed with 24 g of JN-25 silica sol and 2.98 g of L-lysine. The molar ratio of the components in the mixed solution was Cu:KOH:SiO2:H2O:L-lysine = 0.37:0.2:1:30:0.2. The mixture was stirred thoroughly at 40 °C for 2 hours. The resulting mixture was then transferred to a reaction vessel lined with polytetrafluoroethylene and reacted at 85 °C for 24 hours at 100 rpm, followed by a further increase in temperature to 170 °C and reaction for 3 days. The reaction product was dried overnight at 100 °C, granulated, calcined in air at 440 °C for 6 hours, and then 2 wt.% graphite additive and 3 wt.% deionized water were added. After thorough mixing, the mixture was pressed into tablets to obtain the catalyst.

[0094] The catalyst contains 29.3 wt.% CuO, 9.2 wt.% K₂O, 0.7 wt.% Na₂O, 58.8 wt.% silica, and 2.0 wt.% graphite. The average particle size of the CuO particles is 1.5 nm, and the dispersion of copper species in the catalyst is 20%. The static contact angle of the catalyst is as follows: Figure 3 As shown, the static contact angle of the catalyst is 59.99°.

[0095] Example 3

[0096] 12.60 g of Cu(NO3)2·6H2O and 0.81 g of NaOH were dissolved in 72 g of deionized water, and then mixed with 21.26 g of tetraethyl orthosilicate (98%) and 4.47 g of L-lysine. The molar ratio of the components in the mixed solution was Cu:NaOH:SiO2:H2O:L-lysine = 0.42:0.2:1:40:0.3. The mixture was stirred thoroughly at 15 °C for 3 hours. The resulting mixture was then transferred to a reaction vessel lined with polytetrafluoroethylene and reacted at 90 °C for 24 hours at 200 rpm, followed by a reaction at 170 °C for 6 days. The reaction product was dried overnight at 100 °C, granulated, calcined in air at 500 °C for 5 hours, and then 2 wt.% graphite additive and 3 wt.% deionized water were added. After thorough mixing, the mixture was pressed into tablets to obtain the catalyst.

[0097] The catalyst contains 33.1 wt.% CuO, 58.8 wt.% silica, 6.0 wt.% Na₂O, and 2.1 wt.% graphite. The average particle size of the CuO particles is 1.4 nm, and the dispersion of copper species in the catalyst is 23%. The static contact angle of the catalyst is as follows: Figure 4 As shown, the static contact angle of the catalyst is 77.08°.

[0098] Example 4

[0099] 49.33 g of Cu(NO3)2·6H2O and 0.81 g of NaOH were dissolved in 144 g of deionized water, and then mixed with 21.26 g of tetraethyl orthosilicate (98%) and 3.53 g of tetramethylguanidine. The molar ratio of each component in the mixed solution was Cu:NaOH:SiO2:H2O:tetramethylguanidine = 1.65:0.2:1:80:0.3. Other steps were repeated in Example 1.

[0100] The catalyst contains 64.2 wt.% CuO, 31.0 wt.% silica, 3.0 wt.% Na2O, and 1.8 wt.% graphite. The average particle size of CuO is 4.6 nm, the dispersion of copper species in the catalyst is 10%, and the static contact angle of the catalyst is 39.65°.

[0101] Example 5

[0102] Repeat Example 1, but change the hydrothermal reaction conditions from "reacting at 80°C for 24 hours, then raising the temperature to 170°C for 1 day" to "reacting at 170°C for 2 days".

[0103] The catalyst contains 33.1 wt.% CuO, 58.8 wt.% silica, 6.0 wt.% Na2O, and 2.1 wt.% graphite. The average particle size of CuO is 3.2 nm, the dispersion of copper species in the catalyst is 13%, and the static contact angle of the catalyst is 40.24°.

[0104] Example 6

[0105] Repeat Example 1, but change the crystallization conditions to static crystallization.

[0106] The catalyst contains 33.1 wt.% CuO, 58.8 wt.% silica, 6.0 wt.% Na2O, and 2.1 wt.% graphite. The average particle size of CuO is 3.5 nm, the dispersion of copper species in the catalyst is 11%, and the static contact angle of the catalyst is 39.83°.

[0107] Example 7

[0108] Repeat Example 2, but change "4.47 g L-lysine" to "2.24 g L-lysine and 1.96 g α-amino acid".

[0109] The catalyst contains 29.3 wt.% CuO, 9.2 wt.% K2O, 0.7 wt.% Na2O, 58.8 wt.% silica, and 2.0 wt.% graphite. The average particle size of CuO is 1.3 nm, the dispersion of copper species in the catalyst is 23%, and the static contact angle of the catalyst is 55.60°.

[0110] Example 8

[0111] Repeat Example 1, but replace 12.60 g of Cu(NO3)2·6H2O with 26.82 g of Ni(NO3)2·6H2O.

[0112] The catalyst contains 49.5 wt.% NiO, 44.0 wt.% silica, 4.5 wt.% Na₂O, and 2.0 wt.% graphite. The average particle size of the NiO particles is 1.8 nm, the dispersion of nickel species in the catalyst is 18%, and the static contact angle of the catalyst is 41.15°. TEM images of the catalyst are shown below. Figure 5 As shown, its STEM photograph and elemental distribution map are as follows: Figure 6 As shown, the catalyst structure is nickel oxide embedded in a silica support.

[0113] Example 9

[0114] Repeat Example 8, but change the hydrothermal reaction conditions from "reacting at 80°C for 24 hours, then raising the temperature to 170°C for 1 day" to "reacting at 170°C for 2 days".

[0115] The catalyst contains 49.5 wt.% NiO, 44.0 wt.% silica, 4.5 wt.% Na2O, and 2.0 wt.% graphite. The average particle size of NiO is 4.1 nm, the dispersion of nickel species in the catalyst is 14%, and the static contact angle of the catalyst is 39.54°.

[0116] Example 10

[0117] Repeat Example 8, but change the crystallization conditions to static crystallization.

[0118] The catalyst contains 49.5 wt.% NiO, 44.0 wt.% silica, 4.5 wt.% Na2O, and 2.0 wt.% graphite. The average particle size of NiO is 4.1 nm, the dispersion of nickel species in the catalyst is 12%, and the static contact angle of the catalyst is 38.90°.

[0119] Comparative Example 1

[0120] Repeat Example 1, but without adding tetramethylguanidine.

[0121] The catalyst contains 33.1 wt.% CuO, 58.8 wt.% silica, 6.0 wt.% Na₂O, and 2.1 wt.% graphite. The average particle size of the CuO particles is 11 nm, and the dispersion of copper species in the catalyst is 5%. The static contact angle of the catalyst is as follows: Figure 7 As shown, the static contact angle of the catalyst is 42.3°.

[0122] Comparative Example 2

[0123] The catalyst was prepared in an open reactor and carried out as follows: In a sedimentation tank with a stirrer, a sodium carbonate solution (containing 23.0 g of sodium carbonate) was co-precipitated with 748 g of silica sol JN-25. The precipitation temperature was controlled at 70°C, and then aged at 70°C for 30 min. Then, a copper nitrate solution (containing 88.0 g of copper) was added to the above precipitate, and the precipitation temperature was maintained at 70°C. Oxalic acid solution was added to bring the final pH of the precipitation to 7.2. After washing, drying, pulverizing, and calcining at 420°C for 4 hours, an appropriate amount of water and graphite were added, and finally, the catalyst was pressed into tablets to obtain a usable catalyst.

[0124] The catalyst contains 34.8 wt.% copper oxide, 58.8 wt.% silica, 4.3 wt.% Na₂O, and 2.1 wt.% graphite. The average particle size of CuO is 13 nm, and the dispersion of copper species in the catalyst is 3%.

[0125] Comparative Example 3

[0126] Repeat Example 8, but without adding tetramethylguanidine.

[0127] The catalyst contains 49.5 wt.% NiO, 44.0 wt.% silica, 4.5 wt.% Na2O, and 2.0 wt.% graphite. The average particle size of NiO is 8.1 nm, the dispersion of nickel species in the catalyst is 9%, and the static contact angle of the catalyst is 39.45°.

[0128] Comparative Example 4

[0129] Take 18.52 g of Ni(NO3)2·6H2O, add deionized water to prepare a solution, and use the impregnation method to impregnate 4.36 g of silica (specific surface area 200 m²) with the nickel nitrate solution. 2 / g), impregnated overnight. Then the product was dried in an oven at 100°C, and the resulting solid was calcined in air at 540°C for 4 hours. 2 wt.% graphite additive and 3 wt.% deionized water were added, mixed thoroughly, and then compressed into tablets to obtain the catalyst.

[0130] The catalyst contains 50.5 wt.% NiO, 47.5 wt.% silica, and 2.0 wt.% graphite. The particle size is 20 nm, the nickel species dispersion is 2%, and the static contact angle is 38.87°.

[0131] The catalysts of Examples 1-7 and Comparative Examples 1-2 were subjected to reduction treatment, and their catalytic activity in the dehydrogenation reaction of cyclohexanol was evaluated. The results are shown in Appendix Table 1.

[0132] Table 1. Evaluation results of catalytic activity of cyclohexanol dehydrogenation reaction in Examples 1-7 and Comparative Examples 1-2.

[0133] Example 1 33.1 63.5％ 98.5％ Example 2 29.3 63.2％ 99.2％ Example 3 33.1 63.6％ 99.9％ Example 4 64.2 61.2％ 98.3％ Example 5 33.1 60.7％ 99.6％ Example 6 33.1 61.3％ 98.7％ Example 7 29.3 63.5％ 99.8％ Comparative Example 1 33.1 57.6％ 93.3％ Comparative Example 2 34.8 56.7％ 93.1％

[0134] Table 1, comparing Examples 1-7 with Comparative Examples 1-2, shows that this method, by adding appropriate proportions of tetramethylguanidine or lysine and employing a two-step crystallization method under rotating conditions, can prepare copper-silicon catalysts with small average CuO particle size and high copper species dispersion. Compared with copper-silicon catalysts with the same CuO content, the catalyst prepared by the method of this invention exhibits higher cyclohexanol conversion and cyclohexanone selectivity in the cyclohexanol dehydrogenation reaction. The catalyst prepared by the method proposed in this invention clearly has better performance.

[0135] By comparing Example 1 with Examples 5 and 6, it can be seen that, under the condition of adding an appropriate amount of tetramethylguanidine, the hydrophilicity and hydrophobicity of the catalyst surface can be further modulated by adjusting the hydrothermal treatment conditions, so as to further improve the selectivity of the catalyst for cyclohexanone in the dehydrogenation reaction of cyclohexanol.

[0136] The catalysts of Examples 8-10 and Comparative Examples 3-4 were subjected to reduction treatment, and their catalytic activity in the dry reforming reaction of methane and carbon dioxide was evaluated. The results are shown in Appendix Table 2.

[0137] Table 2. Evaluation results of catalytic activity of methane and carbon dioxide dry reforming reaction in Examples 8-10 and Comparative Examples 3-4.

[0138]

[0139]

[0140] As shown in Table 2, comparing Examples 8-10 and Comparative Examples 3-4, it is evident that the nickel-silicon catalyst prepared using the method proposed in this invention exhibits smaller average particle size and higher dispersibility of NiO nanoparticles. Compared to the catalysts with the same supported type prepared in the comparative examples, the catalyst prepared using the method proposed in this invention demonstrates higher methane conversion and superior catalytic stability in the dry reforming reaction of methane and carbon dioxide. The catalyst prepared using the method proposed in this invention clearly exhibits better performance.

[0141] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst embedded in a metal oxide, characterized in that, Includes the following steps: (1) Thoroughly mix metal salt, alkali, silicon source, water, amino acid and / or compound containing guanidine functional group to obtain a mixed solution, and then place the mixed solution in a sealed container for reaction; (2) The resulting reaction product is dried and calcined; Wherein, the metal salt is selected from at least one of copper, manganese and nickel; the base is at least one of sodium hydroxide, lithium hydroxide and potassium hydroxide; the amino acid is α-amino acid and / or L-lysine; and the compound containing the guanidine functional group is selected from at least one of tetramethylguanidine, dodecylguanidine hydrochloride and polyhexamethylene biguanide hydrochloride. In the mixed solution, the molar ratio of metal salt: base: SiO2 provided by silicon source: H2O: (amino acids and / or compounds containing guanidine functional groups) is (0.13~3.47):(0.1~0.5):1:(10~100):(0.1~1.0); the pH of the mixed solution is greater than 7. The reaction conditions include: first reacting at 80~90 ℃ for 0.5~3 days, then raising the temperature to 150~180 ℃ and reacting for 1~7 days; the reaction is carried out at a dynamic rotation speed of 1~500 rpm.

2. The method according to claim 1, wherein, The metal salt is selected from at least one of metal nitrates, sulfates, and hydrochlorides; and / or The silicon source is at least one of silica sol, silica fume, sodium silicate, and tetraethyl orthosilicate.

3. The method according to claim 1, wherein, The mixing conditions include: mixing by stirring, and a mixing temperature of 5~50℃; and / or, The mixing time is 0.5 to 5 hours.

4. The method according to claim 3, wherein, The mixing conditions include a mixing time of 2 to 3 hours.

5. The method according to claim 3, wherein, The mixing conditions include using one or more of the following methods to assist mixing: magnetic field, electric field, and infrared lamp irradiation.

6. The method according to claim 1, wherein, The drying temperature is 50~200℃.

7. The method according to claim 6, wherein, The drying temperature is 80~100℃.

8. The method according to claim 1, wherein, The roasting conditions include a temperature of 300~550 ℃ and a time of 2~6 h.

9. The method according to claim 8, wherein, The roasting conditions include a temperature of 400~550 ℃.

10. A catalyst with an embedded metal oxide prepared by the method of any one of claims 1-9.

11. The catalyst with embedded metal oxide according to claim 10, wherein, The catalyst comprises silicon dioxide and metal oxides, with the metal oxides embedded in a silicon dioxide support.

12. The catalyst with embedded metal oxide according to claim 11, wherein, Based on the total weight of the catalyst, the catalyst contains 15-70 wt.% metal oxides and 30-85 wt.% silica; and / or, The catalyst dispersion is 10-30%.

13. The catalyst with embedded metal oxide according to claim 12, wherein, Based on the total weight of the catalyst, the catalyst contains 25-45 wt.% metal oxides and 55-75 wt.% silica; and / or, The catalyst dispersion is 15-30%.

14. The catalyst with embedded metal oxide according to claim 11, wherein, The metal in the metal oxide is selected from at least one of copper, manganese, and nickel.

15. The catalyst with embedded metal oxide according to claim 11, wherein, The average particle size of the metal oxide is 1~5 nm.

16. The catalyst with embedded metal oxide according to claim 15, wherein, The average particle size of the metal oxide is 1~2 nm.

17. The catalyst with embedded metal oxide according to claim 11, wherein, The static contact angle of the catalyst with water is 20~80°.

18. The catalyst with embedded metal oxide according to claim 17, wherein, The catalyst has a static water contact angle of 30~80°.

19. The use of the catalyst with metal oxide intercalation according to any one of claims 10-18 in the dehydrogenation of cyclohexanol or the dry reforming reaction of methane and CO2.

20. The application according to claim 19, wherein, Before use, the catalyst is reduced with hydrogen-containing gas. The conditions for the reduction treatment include a reduction temperature of 180~250 ℃.

Images