Supported complex metal-oxide catalysts, their preparation and use in the direct synthesis of high carbon isomeric olefins from methanol and ethanol

Abstract

This invention discloses a supported composite metal-oxide catalyst, its preparation, and its application in the direct synthesis of high-carbon isoolefins from methanol and ethanol. The catalyst consists of a silicon-based support, metal Cu, and oxides. Based on the total mass of the catalyst, the loading of metal Cu is 0.1–30 wt.%, and the loading of oxides is 0–30 wt.%. The oxides are oxides of elements from Groups IIIB, IVB, and / or IIIA of the periodic table. The catalytic system of this invention is stable under high-temperature reaction conditions. Furthermore, when isobutene is the target product, the conversion rate of ethanol can reach 100%, the yield of isobutene is 41.5%, and the total yield of high-carbon isoolefins reaches 41.5%. When isoprene is the target product, the conversion rate of ethanol can reach 98.2%, the yield of isoprene is 17.9%, and the total yield of high-carbon isoolefins reaches 23.9%.

Description

Technical Field

[0001] This invention relates to a supported composite metal-oxide catalyst and its preparation method, and its application in the direct synthesis of high-carbon isoolefins from methanol and ethanol. Background Technology

[0002] Isobutylene is an important chemical raw material for the synthesis of various commercial and specialty chemicals. For example, through etherification with methanol and ethanol, it produces methyl tert-butyl ether and ethyl tert-butyl ether, respectively, which are fuel additives that improve the octane number of gasoline. Through dimerization, it can also produce isooctane, which is also used as an octane enhancer in gasoline. Isobutylene oligomers have various uses, such as as ingredients in cosmetics. A route for the dimerization of bio-based isobutylene to produce p-xylene was also proposed several years ago. In addition, a noteworthy route is the oxidation of isobutylene to methacrolein, used in the production of methacrylic acid and methyl methacrylate, a relatively common process in Asia. Isobutylene can be used to derive a variety of products, and a feasible and reasonable development plan for isobutylene and its upstream and downstream products can bring broad prospects for the development of my country's chemical and petroleum industries. The main production methods of isobutylene include extraction from C4 fractions using sulfuric acid extraction, isobutane-propylene co-oxidation, adsorption separation, isomerization, MTBE cracking, and tert-butanol dehydration.

[0003] Isoprene is a strategically important resource widely used across various industries. It plays a crucial role in rubber synthesis, medicine, pesticides, fine chemicals, synthetic lubricants, additives, rubber vulcanizing agents, and catalysts. Isoprene rubber (1,4-cis-polyisoprene) was one of the first general-purpose synthetic rubbers synthesized. It serves as an effective substitute for natural rubber, and the synthesis of polyisoprene and its derivatives is a preferred material for many applications, particularly as elastomers in the automotive, sports, footwear, and medical industries, demonstrating significant value in medicine as well. There are three main methods for producing isoprene: physical extraction, biosynthesis, and chemical synthesis. Physical extraction uses the C5 fraction, a byproduct of naphtha cracking to produce ethylene, as raw material, to extract and separate isoprene. However, due to the impact of shale gas technology, C5 resources are becoming scarce. Biosynthesis is still in the laboratory research stage. Chemical synthesis methods include isopentane / isoprene dehydrogenation, acetylene-acetone method, propylene dimerization, and enal method. In chemical synthesis, the isopentane / isoprene dehydrogenation method has a reaction temperature of 500–600℃ and high energy consumption; the acetylene-acetone method has a relatively high product yield and mild operating conditions, but the raw materials acetylene and acetone are expensive; the propylene dimerization method suffers from low yield, harsh reaction conditions, and high raw material consumption; the enaldehyde method uses isobutylene and formaldehyde to synthesize isoprene under acidic conditions, but it suffers from severe liquid acid corrosion, environmental pollution, difficulty in reuse, low selectivity of solid acid products, and easy carbon deposition and deactivation. Currently, the dehydrogenation method, acetylene-acetone method, and propylene dimerization method have been phased out due to their lack of competitiveness, and isoprene is mainly produced through the enaldehyde method. However, whether it is a physical extraction method or a chemical synthesis method, the raw materials are derived from petrochemical resources. With the increasing depletion of global petrochemical resources and the continuous rise in prices, the development of isoprene and its downstream products is severely limited. Due to factors such as production processes and raw material supply, my country has become a net importer of isoprene since 2017. Therefore, developing the production of isoprene using abundant renewable biomass resources as raw materials has become an important research and development direction.

[0004] We propose a method to synthesize isobutylene and isoprene under mild reaction conditions using renewable methanol and ethanol as raw materials via a coupling of the Guerbet and Prins reactions. The reaction process consists of five basic reactions: (I) dehydrogenation: methanol and ethanol are dehydrogenated to formaldehyde and acetaldehyde, respectively; (II) condensation: formaldehyde and acetaldehyde condense to 3-hydroxypropanal; (III) dehydration: 3-hydroxypropanal is dehydrated to acrolein; (IV) hydrogenation: acrolein is hydrogenated to propanol. The propanol produced in the reaction then undergoes reactions (I-IV) to generate isobutanol. Finally, isobutanol is dehydrated to isobutylene, which further condenses with formaldehyde to formoprene (V). The reaction pathway is as follows: Figure 1 As shown.

[0005] In this invention, we designed and prepared a supported composite metal-oxide catalyst and applied it to the catalytic reaction of methanol and ethanol. We proposed and realized the direct synthesis of isobutylene and isoprene from renewable methanol and ethanol as raw materials, and obtained high yields of isobutylene and isoprene. Summary of the Invention

[0006] The purpose of this invention is to provide a supported composite metal-oxide catalyst and its preparation method, as well as its application in the synthesis of high-carbon isoolefins from methanol and ethanol.

[0007] The technical solution of the present invention is as follows:

[0008] A supported composite metal-oxide catalyst is composed of a silicon-based support, metal Cu, and oxides; based on the total mass of the catalyst, the loading of metal Cu is 0.1–30 wt.%, preferably 1.0–20 wt.%; the loading of oxides is 0–30 wt.%, preferably 1.0–20 wt.%.

[0009] The silicon-based support can be ordinary SiO2, fumed SiO2, aerogel SiO2, ZSM-5, SBA-15, SBA-16, MCM-41, KIT-6, Y-type molecular sieve, MFI-type molecular sieve, Beta-type molecular sieve, column chromatography silica gel, mordenite, caloite, chalcogenide, etc.; fumed SiO2, aerogel SiO2, or SBA-15 are preferred; large specific surface area (>200m²) is required. 2 The material ( / g) is beneficial for the dispersion of metallic Cu and oxide particles, and has a better catalytic effect;

[0010] The oxides are oxides of elements in Group IIIB, IVB and / or IIIA of the periodic table, preferably oxides of Ce, Zr, Al and / or La.

[0011] Traditional methods for preparing supported catalysts result in low surface metal content and weak interactions between the support and the supported metal, leading to agglomeration of active metal particles and loss during the reaction. This invention utilizes a combination of precipitation, ammonia stripping, and impregnation methods to load metals and oxides onto a support, achieving highly dispersed supported metals and oxides on the support surface and improving the interaction between the support and the metal, thereby enhancing the catalyst's catalytic activity. The catalyst prepared by this invention largely retains the structural properties of the original support material, and the preparation method is simple and easy to implement.

[0012] In this invention, one preparation method involves using a precipitation-ammonia stripping method to simultaneously and uniformly load a metallic Cu precursor and an oxide precursor onto a support, thereby obtaining a supported composite metal-oxide catalyst. Another preparation method involves first loading the metallic Cu precursor onto the support using an ammonia stripping method, and then loading the oxide precursor onto the support using an impregnation method, thus obtaining a supported composite metal-oxide catalyst. In this invention, the loading amount of metallic Cu relative to the catalyst is 0.1–30 wt.%, and the loading amount of the oxide relative to the catalyst is 0–30 wt.%. Too low a loading amount results in insignificant catalytic activity, while a high loading amount causes metallic Cu or oxide to accumulate on the support surface (Comparative Example 1), leading to a decrease in the yield of high-carbon isomeric olefins.

[0013] Specifically, when using the precipitation-ammonia stripping method, the preparation method of the supported composite metal-oxide catalyst of the present invention is as follows:

[0014] Metallic Cu precursor and oxide precursor were added to water and stirred to dissolve. Then, a silicon-based support was added and stirred to mix. Ammonia was added dropwise until the pH of the reaction solution was 12. The mixture was stirred for 8–12 h and heated to 90 °C to evaporate ammonia until the reaction solution was neutral. Then, it was heated to 120 °C to evaporate to dryness. The resulting solid was dried in an oven and then transferred to a muffle furnace and calcined at 450 °C for 4 h. After being removed, it was ground to obtain a supported composite metal-oxide catalyst.

[0015] The precipitation-ammonia stripping method is characterized by the following: when the metal Cu precursor and the oxide precursor are added simultaneously, ammonia water is added dropwise. The metal Cu precursor and the oxide precursor first form hydroxides, which are uniformly mixed and precipitated on the fumed silica support. As ammonia water is continued to be added until pH=12, copper hydroxide will be transformed into a copper ammonia complex. During the ammonia stripping process at 90℃, the copper ammonia complex reacts with the fumed silica support to form layered copper silicate. In the catalyst prepared by this method, there will be an interaction between the metal Cu and the oxide, resulting in a synergistic catalytic effect.

[0016] Specifically, when using the ammonia stripping-impregnation method, the preparation method of the supported composite metal-oxide catalyst of the present invention is as follows:

[0017] (1) Add the metal Cu precursor to water, stir to dissolve, then add the silicon-based support, stir to mix, add ammonia dropwise until the pH of the reaction solution is 12, stir for 8-12 hours, heat to 90°C to evaporate ammonia until the reaction solution is neutral, then heat to 120°C to evaporate to dryness, place the obtained solid material in an oven to dry, transfer it to a muffle furnace and calcine at 450°C for 4 hours, take it out and grind it to obtain the supported metal Cu catalyst;

[0018] (2) Add the supported metal Cu catalyst and oxide precursor obtained in step (1) to water, stir for 8 to 12 hours, then heat to 120°C to dry, dry the obtained solid material in an oven, then transfer it to a muffle furnace and calcine at 450°C for 4 hours, take it out and grind it to obtain the supported composite metal-oxide catalyst.

[0019] The characteristics of the ammonia stripping-impregnation method are as follows: when the metal Cu precursor and the oxide precursor are added stepwise, ammonia water is added dropwise. The metal Cu precursor first forms hydroxide and precipitates on the fumed silica support. As ammonia water is added dropwise until pH=12, copper hydroxide is transformed into a copper ammonia complex. During the ammonia stripping process at 90℃, the copper ammonia complex reacts with the fumed silica support to form layered copper silicate. Then, the oxide precursor is added by impregnation. At this time, the oxide precursor may cover the metal Cu, reducing the number of active sites of metal Cu. At the same time, the interaction between metal Cu and oxide is relatively weak, and the synergistic catalytic effect is also relatively weak.

[0020] In the above preparation method, the metallic Cu precursor is selected from one or more of the following: Cu oxides, fluorides, chlorides, bromides, iodides, selenides, nitrates, sulfates, thiocyanates, phosphates, phosphites, pyrophosphates, carbonates, bicarbonates, acetylacetonates, formates, acetates, acetates, butyrates, iodates, oxalates, citrates, gluconates, tartrates, fluoroborates, trifluoroacetates, tetrafluoroborates, chromites, perchlorates, glycine salts, ethylenediaminetetraacetate, phthalocyanine compounds, and ethylenediamine dihydrogen phosphate compounds; preferably, one or more of the following: Cu nitrates, acetylacetonates, formates, acetates, acetates, oxalates, and citrates.

[0021] The oxide precursor is selected from one or more of the following: oxides, fluorides, chlorides, bromides, iodides, selenides, nitrates, sulfates, thiocyanates, phosphates, phosphites, pyrophosphates, carbonates, bicarbonates, acetylacetonates, formates, acetates, acetates, butyrates, iodates, oxalates, citrates, gluconates, tartrates, fluoroborates, trifluoroacetates, tetrafluoroborates, chromites, perchlorates, glycinates, ethylenediaminetetraacetate, phthalocyanine compounds, and ethylenediamine dihydrogen phosphate compounds; preferably, one or more of the following: nitrates, acetylacetonates, formates, acetates, acetates, oxalates, and citrates of the following group elements: group IIIB, group IVB, and / or group IIIA.

[0022] The supported composite metal-oxide catalyst prepared by the above method is affected by factors such as the dispersion degree of the active metal, the particle size of the metal nanoparticles, the valence electron structure of the metal, and the acidity or basicity of the oxide, all of which influence the catalyst's reactivity and product selectivity. Uniform dispersion of the metal and oxide on the support surface and enhanced interaction with the support prevent the metal and oxide particles from agglomerating and being lost during the reaction. This allows for efficient and synergistic catalytic action by each metal and oxide, while also exhibiting good high-temperature stability. In this invention, the catalyst's reactivity, product selectivity, and high-temperature stability can be adjusted by changing the type of precursor, loading, reduction conditions, and calcination temperature. These methods can be used individually or in combination.

[0023] The supported composite metal-oxide catalyst of this invention can be applied to the direct synthesis of higher carbon isoolefins from methanol and ethanol. The specific application method is as follows:

[0024] First, 0.1–1.0 g of the supported composite metal-oxide catalyst was placed in a fixed-bed reaction tube for reduction, specifically: the temperature was increased from 50 °C to 400–600 °C in high-purity hydrogen and maintained for 2–6 h; after catalyst reduction, a mixed solution of methanol and ethanol with a molar ratio of (3–30):1 was fed into the reaction tube at a liquid feed rate of 0.01–1.0 mL / min using a high-pressure constant flow pump, and the reaction was carried out at a reaction temperature of 150–500 °C, a nitrogen flow rate of 1–50 mL / min, and a total pressure of 0.1–10 MPa; the reaction products were then passed through a gas chromatograph (PoraPLOT QH capillary column, FID detector) for component composition analysis to obtain the catalytic results under each reaction condition;

[0025] The preferred amount of the supported composite metal-oxide catalyst is 0.2g.

[0026] The preferred molar ratio of methanol to ethanol is (6-12):1;

[0027] The preferred reaction conditions are 250–400℃, nitrogen flow rate 5–30 mL / min, and total pressure 1–5 MPa; the preferred reduction temperature is 400℃, and the preferred reduction time is 4 h.

[0028] The raw materials methanol and ethanol can be chemical products of chemical purity, and ethanol can also be obtained through biological fermentation broth;

[0029] After prolonged high-temperature evaluation, the catalyst of this invention still exhibits similar catalytic activity when cooled back to the initial reaction temperature. Therefore, the catalyst is stable under high temperature and high pressure, and its catalytic activity is not significantly reduced.

[0030] The advantages of this invention compared to related technologies are as follows: This invention employs a combination of multiple catalyst preparation methods to obtain a supported composite metal-oxide catalyst; this catalytic system enables the direct synthesis of high-carbon isomeric olefins from methanol and ethanol as raw materials. Under optimized reaction conditions, the selectivity of isobutylene and isoprene in the products can reach 50.2% and 18.2%, respectively. Specifically:

[0031] 1) The reaction for synthesizing isomerized olefins from methanol and ethanol, as disclosed in this invention, is carried out in a fixed bed. Methanol is a fundamental product of modern industry, and its integration into the isomerization olefin production process helps reduce the raw material costs of this production process. Bioethanol is currently the largest-volume product in the bio-fermentation industry, and high-carbon isomerized olefins are products with higher value compared to methanol and ethanol.

[0032] 2) The novel supported composite metal-oxide catalyst of this invention exhibits stable properties in the reaction system and can be used for extended periods, which is beneficial for reducing production costs. This catalyst enables the direct synthesis of isobutylene and isoprene from the reaction of methanol and ethanol. Under preferred catalyst and optimized reaction conditions, with isobutylene as the target product, the ethanol conversion rate can reach 100%, the isobutylene selectivity is 50.2%, the isobutylene yield is 41.5%, and the total yield of higher carbon isoolefins reaches 41.5% (Example 7). With isoprene as the target product, the ethanol conversion rate can reach 98.2%, the isoprene selectivity is 18.2%, the isoprene yield is 17.9%, and the total yield of higher carbon isoolefins reaches 23.9% (Example 16). Example 7 shows a high isobutylene yield on the oxide-free catalyst; in Example 16, after the addition of oxides, isobutylene further reacts with formaldehyde to generate isoprene. Attached Figure Description

[0033] Figure 1 The reaction pathway for the synthesis of isobutylene and isoprene from methanol and ethanol.

[0034] Figure 2 XRD patterns of Cu / SiO2 catalysts after reduction with different Cu contents.

[0035] Figure 3 N2 physical adsorption-desorption curves (left) and pore size distribution diagrams (right) of Cu / SiO2 catalysts with different Cu contents.

[0036] Figure 4 H2-TPR diagrams of Cu / SiO2 catalysts with different Cu contents.

[0037] Figure 5 NH3-TPD diagrams of Cu / SiO2 catalysts with different Cu contents.

[0038] Figure 6CO2-TPD diagrams of Cu / SiO2 catalysts with different Cu contents.

[0039] Figure 7 XRD pattern of reduction by 10wt.% Cu-10wt.% M / SiO2 catalyst.

[0040] Figure 8 N2 physical adsorption-desorption curves (left) and pore size distribution (right) of 10wt.% Cu-10wt.% M / SiO2 catalyst.

[0041] Figure 9 H2-TPR diagram of 10wt.% Cu-10wt.% M / SiO2 catalyst.

[0042] Figure 10 NH3-TPD diagram of 10wt.% Cu-10wt.% M / SiO2 catalyst.

[0043] Figure 11 CO2-TPD diagram of 10wt.% Cu-10wt.% M / SiO2 catalyst. Detailed Implementation

[0044] The key to this invention is the development of a supported composite metal-oxide catalyst that can promote the conversion of methanol and ethanol into high-carbon isoolefins. The preparation method is described in detail below. This invention can be modified in various ways and is not limited to the examples.

[0045] The following examples further illustrate the implementation of the catalyst and catalytic reaction in this invention, but the scope of protection of this invention is not limited to the contents listed in the examples.

[0046] Example 1

[0047] Cu / SiO2 catalysts with different Cu contents were prepared by ammonia stripping method.

[0048] Weigh 0.07603 g of Cu(NO3)2·3H2O and add it to a 100 mL beaker containing an appropriate amount of distilled water (about 40 mL). Stir until copper nitrate is completely dissolved. Then add 2 g of gaseous SiO2 and about 60 mL of distilled water. Continue stirring for about 3 hours until the mixture is homogeneous. Add ammonia water dropwise until the pH of the solution in the beaker is about 12 and stir overnight. Then heat in an oil bath at 90 °C to evaporate ammonia until the solution is neutral. Then change the temperature to 120 °C to evaporate to dryness. Then transfer the material in the beaker to an oven and dry at 100 °C for 4 hours. Take it out, grind it into powder, and transfer it to a crucible. Finally, place it in a muffle furnace and calcine at 450 °C for 4 hours. Take it out and grind it into fine powder to obtain a 1 wt.% Cu / SiO2 catalyst.

[0049] Example 2

[0050] Weigh 0.3802 g of Cu(NO3)2·3H2O, and follow the same steps as in Example 1 to prepare a 5 wt.% Cu / SiO2 catalyst.

[0051] Example 3

[0052] Weigh 0.7603g Cu(NO3)2·3H2O, and follow the same steps as in Example 1 to prepare a 10wt.% Cu / SiO2 catalyst.

[0053] Example 4

[0054] Weigh 1.1405g Cu(NO3)2·3H2O, and follow the same steps as in Example 1 to prepare a 15wt.% Cu / SiO2 catalyst.

[0055] Example 5

[0056] Weigh 1.5207g Cu(NO3)2·3H2O, and follow the same steps as in Example 1 to prepare a 20wt.% Cu / SiO2 catalyst.

[0057] Example 6

[0058] The Cu / SiO2 catalysts with different Cu contents prepared by the ammonia stripping method were applied to the synthesis of high-carbon isoolefins from methanol and ethanol. The reaction conditions were as follows: a micro fixed-bed reactor (Shanghai Yanzheng Electronic Technology Co., Ltd., YZUBPR-G2-L2-B) was used to evaluate the catalyst. First, 0.2 g of catalyst was weighed and placed in a fixed-bed reaction tube, with the lower end of the tube compressed by a liner and quartz wool. Then, a reduction activation treatment was performed by introducing high-purity hydrogen into the reaction tube, raising the temperature from 50°C to 400°C, and maintaining this temperature for 4 hours. After reduction, the H2 valve was closed, and the N2 pressure was adjusted to 2 MPa. Subsequently, N2 was used as the fixed-bed carrier gas at a flow rate of 10 mL / min. Methanol and ethanol (molar ratio 6:1) were used as feedstock, and a high-pressure constant flow pump was used to feed the feedstock into the reaction tube at a liquid feed rate of 0.07 mL / min. The reaction temperature was 300°C, and the product was sampled through a ten-port valve in a high-temperature holding section for online chromatographic analysis.

[0059] Table 1 Catalytic activity of Cu / SiO2 catalysts with different Cu contents

[0060]

[0061] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0062] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0063] Example 7

[0064] The 5wt.% Cu / SiO2 and 10wt.% Cu / SiO2 catalysts prepared by the ammonia stripping method were applied to the synthesis of higher carbon isoolefins from methanol and ethanol. To investigate the catalytic effect of the catalysts at different temperatures and whether they could maintain good catalytic performance at high temperatures, a reaction was designed under the conditions of Example 6, with only the reaction temperature varied. Specifically, the reactions were carried out at 250℃, 300℃, 350℃, and 400℃ for 2 hours, and then cooled to 250℃ for another 2 hours. The reaction products at each temperature were sampled via a ten-way valve through a high-temperature holding section and analyzed online by chromatography.

[0065] Table 2 Catalytic activity of 5 wt.% Cu / SiO2 catalyst at different reaction temperatures

[0066]

[0067] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0068] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0069] Table 3 Catalytic activity of 10 wt.% Cu / SiO2 catalyst at different reaction temperatures

[0070]

[0071] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0072] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0073] Comparative Example 1

[0074] To compare the effect of Cu loading on catalytic activity, the prepared 15 wt.% Cu / SiO2 catalyst was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the reaction conditions were the same as in Example 7. It can be seen that at 400 °C, the selectivity for isobutylene decreased significantly, leading to a reduction in the yield of higher carbon isoolefins to 25.9%.

[0075] Table 4 Catalytic activity of 15 wt.% Cu / SiO2 catalyst at different reaction temperatures

[0076]

[0077] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0078] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0079] Example 8

[0080] A 10 wt.% Cu-10 wt.% M / SiO2 catalyst was prepared by precipitation-ammonia stripping method.

[0081] Weigh 0.7603g Cu(NO3)2·3H2O and 0.6198g Ce(NO3)3·6H2O, add them to a 100mL beaker containing an appropriate amount of distilled water (about 40mL), and stir until the nitrate is completely dissolved. The subsequent steps are the same as the catalyst preparation steps in Example 1.

[0082] Example 9

[0083] Weigh 0.7603g Cu(NO3)2·3H2O and 0.9413g La(NO3)3, add them to a 100mL beaker containing an appropriate amount of distilled water, and stir until the nitrate is completely dissolved. The subsequent steps are the same as the catalyst preparation steps in Example 1.

[0084] Example 10

[0085] Weigh 0.7603g Cu(NO3)2·3H2O and 0.4678g Zr(NO3)4·5H2O, add them to a 100mL beaker containing an appropriate amount of distilled water, and stir until the nitrate is completely dissolved. The subsequent steps are the same as the catalyst preparation steps in Example 1.

[0086] Example 11

[0087] Weigh 0.7603g Cu(NO3)2·3H2O and 2.7808g Al(NO3)3·9H2O, add them to a 100mL beaker containing an appropriate amount of distilled water, and stir until the nitrate is completely dissolved. The subsequent steps are the same as the catalyst preparation steps in Example 1.

[0088] Example 12

[0089] The 10wt.% Cu-10wt.% M / SiO2 catalysts containing different oxides, prepared by the precipitation-ammonia stripping method, were applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the reaction conditions were the same as in Example 6.

[0090] Table 5 Catalytic activity of 10wt.% Cu-10wt.% M / SiO2 catalysts with different oxides added.

[0091]

[0092] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0093] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0094] Example 13

[0095] The 10wt.% Cu-10wt.% CeO2 / SiO2 catalyst prepared by precipitation-ammonia stripping method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0096] Table 6. Catalytic activity of 10wt.% Cu-10wt.% CeO2 / SiO2 catalysts at different reaction temperatures.

[0097]

[0098] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0099] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0100] Example 14

[0101] The 10wt.% Cu-10wt.% ZrO2 / SiO2 catalyst prepared by precipitation-ammonia stripping method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0102] Table 7 Catalytic activity of 10wt.% Cu-10wt.% ZrO2 / SiO2 catalyst at different reaction temperatures

[0103]

[0104]

[0105] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0106] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0107] Example 15

[0108] The 10wt.% Cu-10wt.% Al2O3 / SiO2 catalyst prepared by precipitation-ammonia stripping method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0109] Table 8 Catalytic activity of 10wt.% Cu-10wt.% Al2O3 / SiO2 catalyst at different reaction temperatures

[0110]

[0111] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0112] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0113] Example 16

[0114] The 10wt.% Cu-10wt.% La2O3 / SiO2 catalyst prepared by precipitation-ammonia stripping method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0115] Table 9 Catalytic activity of 10wt.% Cu-10wt.% La2O3 / SiO2 catalyst at different reaction temperatures

[0116]

[0117] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0118] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0119] Comparative Example 2

[0120] To compare with the 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by the precipitation-ammonia stripping method, a 15wt.% Cu-10wt.% N / SiO2 catalyst containing different oxides was prepared by the ammonia stripping-impregnation method.

[0121] The 15wt.% Cu / SiO2 catalyst prepared by the ammonia stripping method in Example 4 was mixed with 0.6198g of Ce(NO3)3·6H2O and dissolved in a 100mL beaker containing an appropriate amount of deionized water. The mixture was stirred overnight. Then, it was heated to dryness in an oil bath at 120℃. After drying, calcining, and grinding, the 15wt.% Cu-10wt.% CeO2 / SiO2 catalyst was obtained.

[0122] Comparative Example 3

[0123] The 15wt.% Cu / SiO2 catalyst prepared by the ammonia stripping method was mixed with 0.9413g of Zr(NO3)4·5H2O and dissolved in a 100mL beaker containing an appropriate amount of deionized water and stirred overnight. Then, it was heated to dryness in an oil bath at 120℃, and after drying, calcination and grinding, the 15wt.% Cu-10wt.% ZrO2 / SiO2 catalyst was obtained.

[0124] Comparative Example 4

[0125] The 15wt.% Cu / SiO2 catalyst prepared by the ammonia stripping method was mixed with 2.7808g of Al(NO3)3·9H2O and dissolved in a 100mL beaker containing an appropriate amount of deionized water and stirred overnight. Then, it was heated to dryness in an oil bath at 120℃, and after drying, calcination and grinding, the 15wt.% Cu-10wt.% Al2O3 / SiO2 catalyst was obtained.

[0126] Comparative Example 5

[0127] The 15wt.% Cu / SiO2 catalyst prepared by the ammonia stripping method was mixed with 0.4678g of La(NO3)3 and dissolved in a 100mL beaker containing an appropriate amount of deionized water and stirred overnight; then it was heated to dryness in an oil bath at 120℃, and after drying, calcination and grinding, the 15wt.% Cu-10wt.% La2O3 / SiO2 catalyst was obtained.

[0128] Comparative Example 6

[0129] The 15wt.% Cu-10wt.% N / SiO2 catalysts of different oxides prepared by the ammonia stripping-impregnation method were applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 6.

[0130] Table 10 Catalytic activity of 15wt.% Cu-10wt.% N / SiO2 catalysts with different oxides added

[0131]

[0132] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0133] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0134] Comparative Example 7

[0135] The 15wt.% Cu-10wt.% CeO2 / SiO2 catalyst prepared by the ammonia stripping-impregnation method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0136] Table 11 Catalytic activity of 15 wt.% Cu-10 wt.% CeO2 / SiO2 catalysts at different reaction temperatures

[0137]

[0138] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0139] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0140] Comparative Example 8

[0141] The 15wt.% Cu-10wt.% ZrO2 / SiO2 catalyst prepared by the ammonia stripping-impregnation method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0142] Table 12 Catalytic activity of 15 wt.% Cu-10 wt.% ZrO2 / SiO2 catalyst at different reaction temperatures

[0143]

[0144] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0145] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0146] Comparative Example 9

[0147] The 15wt.% Cu-10wt.% Al2O3 / SiO2 catalyst prepared by the ammonia stripping-impregnation method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0148] Table 13 Catalytic activity of 15 wt.% Cu-10 wt.% Al2O3 / SiO2 catalyst at different reaction temperatures

[0149]

[0150] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0151] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0152] Comparative Example 10

[0153] The 15wt.% Cu-10wt.% La2O3 / SiO2 catalyst prepared by the ammonia stripping-impregnation method was applied to the synthesis of higher carbon isoolefins from methanol and ethanol. Except for the catalyst, the other reaction conditions were the same as those in Example 7.

[0154] Table 14 Catalytic activity of 15wt% Cu-10wt% La2O3 / SiO2 catalyst at different reaction temperatures

[0155]

[0156] [a]MeOH = methanol; EtOH = ethanol; NPA = n-propanol; IB = isobutylene; IP = isoprene; IBA = isobutanol; other products include ethyl acetate, methyl isobutyrate, methyl acetate, isobutyraldehyde, etc.

[0157] [b]The yield of high-carbon isoolefins relative to EtOH conversion = the yield of isobutylene (IB) + the yield of isoprene (IP).

[0158] As can be seen from the above examples, the 5wt.% Cu / SiO2 and 10wt.% Cu / SiO2 catalysts prepared by the ammonia stripping method are beneficial to the formation of isobutylene, with an isobutylene yield of 41.5% (Example 7). The 10wt.% Cu-10wt.% La2O3 / SiO2 catalyst prepared by the precipitation-ammonia stripping method is beneficial to the formation of isoprene, with an isoprene yield of 17.9% (Example 16). This indicates that the introduction of oxides can promote the further reaction of isobutylene with formaldehyde to isoprene. To understand the reaction activity data, we performed a series of characterization analyses on the catalysts in the examples.

[0159] XRD results and analysis of Cu / SiO2 catalysts with different Cu contents Figure 2 XRD results and analysis: The broad diffraction peak at 2θ = 22.1° belongs to the gas phase SiO2, and the characteristic diffraction peak at 2θ = 36.5° belongs to Cu2O. The catalyst showed three distinct diffraction peaks at 2θ = 43.3°, 50.2°, and 74.2°, which are attributed to Cu. 0 Different diffraction peaks were observed. The XRD pattern clearly shows that on the catalyst with a low Cu content, only pure SiO2 phase peaks appeared in the XRD pattern. This indicates that at low Cu contents, the active Cu component is highly dispersed on the surface of gaseous SiO2, so the Cu phase was not detected. When the Cu content in the catalyst was further increased to 10 wt.%, Cu2O and Cu2O peaks appeared respectively. 0 The diffraction peaks are observed because as the Cu content increases, the number of reduced Cu particles increases, leading to the appearance of corresponding diffraction peaks. With the continued increase in Cu content, Cu₂O and Cu... 0The intensity of the diffraction peaks increased accordingly, indicating that the increase in Cu content caused a change in the size of Cu particles. In general, at low Cu content, Cu particles are more uniformly dispersed on the SiO2 support and do not form large grains, so only the phase peaks of pure SiO2 appear in the XRD pattern; while at high Cu content, due to the increase in Cu content, Cu particles aggregate to form larger grains, thus resulting in corresponding diffraction peaks.

[0160] Results and analysis of N2 physisorption of Cu / SiO2 catalysts with different Cu contents Figure 3 (and Table 15)

[0161] Table 15 Structural properties of Cu / SiO2 catalysts with different Cu contents

[0162]

[0163]

[0164] [a]BET specific surface area.

[0165] [b]The volume of a single-point orifice when P / P0 = 0.99.

[0166] [c] Average aperture calculated using the DFT method.

[0167] N2 physical adsorption results and analysis: From Figure 3 The N2 adsorption-desorption curves show that the prepared catalyst exhibits adsorption in the low-pressure region and a hysteresis loop in the high-pressure region. This adsorption-desorption curve belongs to the typical Type IV in the IUPAC classification, thus classifying it as a mesoporous material. Table 13 shows that the specific surface area of ​​the catalyst gradually increases with increasing Cu content, indicating the formation of new surfaces. This is attributed to the formation of layered copper silicate, which possesses a high specific surface area due to its unique "layered" structure. The increase in Cu content leads to a gradual decrease in pore volume, as more CuO and Cu2O accumulate on the catalyst surface, resulting in a decrease in pore volume. Figure 3 The average particle size distribution diagram shows that at lower Cu loadings, the pore sizes are all distributed in the mesopore range greater than 5 nm. When the Cu content increases to 10 wt.%, the pore size decreases significantly, and both mesopores and micropores appear. Furthermore, with the increase of Cu content, the smaller pore sizes gradually increase. Therefore, it can be inferred that the formation of layered copper silicate is the main reason for the increase in micropores.

[0168] H2-TPR results and analysis of Cu / SiO2 catalysts with different Cu contents Figure 4 ).

[0169] H2-TPR Results and Analysis: In the Cu / SiO2 catalyst prepared by the ammonia stripping method, when the Cu content is low, the Cu exists mainly in the form of highly dispersed Cu. + Species and layered copper silicate. With increasing Cu content, Cu may exist in forms including layered copper silicate, highly dispersed CuO, and large-particle CuO. In Figure 4 In the process, the hydrogen consumption peak around 520℃ can be considered as the hydrogen consumption peak due to the oxygen-containing groups of the support gas phase SiO2 itself. With increasing Cu content, the number, width, and intensity of the reduction peaks all changed significantly. The first reduction peak around 209℃ represents the reduction of layered copper silicate to Cu. + And the reduction of highly dispersed CuO to Cu 0 The second reduction peak at around 228℃ belongs to the reduction of large-particle CuO. When the Cu loading increases from 1 wt.% to 10 wt.%, Cu exists mainly in the form of layered copper silicate and highly dispersed CuO on the gas phase SiO2, and the amount of these substances increases with the increase of loading. When the Cu loading is 10 wt.%, based on the results given by the XRD diffraction peaks, it can be determined that the Cu2O and Cu after the reduction of layered copper silicate and highly dispersed CuO are... 0 A certain degree of aggregation occurs on the support surface. Further increasing the Cu loading to 15 wt.%, a small number of large CuO particles begin to appear. XRD results indicate that Cu is obtained by reducing these large CuO particles. 0 Large Cu particles will accumulate on the carrier surface. 0 When the Cu loading reaches 20 wt.%, the content of large CuO particles also increases with the increase of Cu loading, and the reduced Cu... 0 Further aggregation and growth occur. Overall, Cu species can be well dispersed on the support surface of the Cu / SiO2 catalyst prepared by the ammonia stripping method.

[0170] N2O titration results and analysis of Cu / SiO2 catalysts with different Cu contents (Table 16)

[0171] Table 16 Cu on Cu / SiO2 catalyst 0 Specific surface area

[0172]

[0173] N2O titration results and analysis: With increasing Cu content, Cu on the catalyst... 0 The specific surface area showed a trend of first increasing and then decreasing, reaching a maximum of 347.2 m² when the Cu loading was 10 wt.%. 2 ·g -1In high-load Cu / SiO2 catalysts, the Cu content is high, but after reduction, it aggregates to form large Cu particles. 0 This has been confirmed in previous XRD and H2-TPR analyses, which leads to Cu on the catalyst surface. 0 Reduced active sites, Cu 0 The specific surface area also decreases accordingly. Therefore, the 10 wt.% Cu / SiO2 catalyst (Example 7) has a higher isobutylene yield than the 15 wt.% Cu / SiO2 catalyst (Comparative Example 1).

[0174] NH3-TPD results and analysis of Cu / SiO2 catalysts with different Cu contents Figure 5 ).

[0175] NH3-TPD Results and Analysis: The NH3 desorption peaks in the Cu / SiO2 catalyst prepared by the ammonia stripping method at 100–230 °C and 230–400 °C are attributed to NH3 desorption at the weak and moderate acid sites of the Cu / SiO2 catalyst. These weak and moderate acid sites in Cu / SiO2 may be related to low-valence Cu species, such as Cu... + The peaks with desorption temperatures above 400℃ are attributed to the condensation and dehydration of silanol groups in fumed silica. With increasing Cu content, Cu is loaded onto SiO2 in different forms, generating complex acidic sites. Table 17 shows that the overall number of acidic sites generally increases with increasing Cu content. Furthermore, the number of weakly acidic sites gradually increases with increasing Cu content, while the content of moderately acidic sites does not change significantly when the Cu content is below 15 wt.%, remaining at 0.010 mmol·g. -1 When the Cu content increased to 20 wt.%, the corresponding content of moderately acidic sites increased to 0.023 mmol·g. -1 .

[0176] Table 17 Acid site content of Cu / SiO2 catalysts with different Cu contents

[0177]

[0178] CO2-TPD results and analysis of Cu / SiO2 catalysts with different Cu contents Figure 6 CO2-TPD Results and Analysis: As shown in Table 18, with the increase of Cu loading, the contents of weak and moderately basic sites did not change significantly. The total basic site content for different Cu contents was around 0.015 mmol·g. -1 about.

[0179] Table 18. Base site content of Cu / SiO2 catalysts with different Cu contents

[0180]

[0181] XRD results and analysis of 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by precipitation-ammonia stripping method.

[0182] XRD Results and Analysis: By Figure 7 It can be seen that the 10 wt.% Cu / SiO2 catalyst exhibits a weak Cu2O diffraction peak at 2θ = 36.5° and a weak Cu2O diffraction peak at 2θ = 43.3°. 0 Diffraction peaks. After uniformly loading Cu precursors along with ZrO2, La2O3, and Al2O3 precursors onto gaseous SiO2 using a precipitation-ammonia stripping method, only diffraction peaks of Cu species and SiO2 appeared on the catalyst; no diffraction peaks of other oxides were observed. This indicates that ZrO2, La2O3, and Al2O3 in the catalyst are highly dispersed. For the Cu-CeO2 / SiO2 catalyst, obvious CeO2 diffraction peaks appeared at 2θ = 27.33°, 31.54°, and 45.66°, indicating the presence of aggregated CeO2. For catalysts with added CeO2 and ZrO2, the diffraction peaks attributed to Cu2O were weakened, indicating that the introduction of oxides facilitates better dispersion of Cu2O on the catalyst, which is why the catalyst can promote the further reaction of the intermediate propanol; meanwhile, the diffraction peaks attributed to Cu... 0 The enhanced diffraction peaks indicate that the addition of these two oxides increases the concentration of Cu in the catalyst. 0 A certain degree of aggregation occurred. Although the addition of La2O3 to the Cu / SiO2 catalyst caused the diffraction peaks of Cu2O to disappear, they were attributed to Cu. 0 The diffraction peak intensity was significantly enhanced, indicating that the addition of La2O3 inhibited the growth of Cu. 0 The dispersion on the catalyst is the reason why this catalyst reduces the ethanol conversion rate (comparison between Example 16 and Example 7). It is worth mentioning that in this case, the catalyst promotes the further conversion of n-propanol and isobutylene to isoprene (Example 12). For the catalyst with added Al2O3, there was no effect on the diffraction peaks of Cu2O, but the diffraction of Cu2O was enhanced. 0 The diffraction peak intensity indicates that the introduction of Al2O3 also led to Cu 0 The aggregation of these particles is why this catalyst failed to improve ethanol conversion (Example 12).

[0183] N2 physisorption results and analysis of 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by precipitation-ammonia stripping method Figure 8 (and Table 19).

[0184] Table 19 Structural properties of 10wt.% Cu-10wt.% M / SiO2 catalysts

[0185]

[0186] N2 physisorption results and analysis: Table 19 shows that the specific surface area of ​​the catalyst with added CeO2 decreased slightly, while the addition of ZrO2 increased the specific surface area. The addition of these two oxides did not significantly change the pore size of the catalyst. However, the addition of La2O3 and Al2O3 significantly decreased the specific surface area of ​​the catalyst from 266.6 μm. 2 ·g -1 Reduced to 176.8m respectively 2 ·g -1 and 191.2m 2 ·g -1 This also increases the pore size of the catalyst, from 11.3 nm to 14.5 nm and 13.9 nm, respectively. A decrease in specific surface area and an increase in pore size are generally detrimental to the catalytic reaction, which is consistent with the results of the activity evaluation. The Cu / SiO2 catalyst with added ZrO2 increased the ethanol conversion rate, while the catalysts with added La2O3 and Al2O3 decreased the ethanol conversion rate (Example 12).

[0187] H2-TPR results and analysis of 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by precipitation-ammonia stripping method Figure 9 ).

[0188] H2-TPR Results and Analysis: The graph shows that the 10wt.% Cu / SiO2 catalyst only exhibits a reduction peak around 209℃, indicating the reduction of layered copper silicate to Cu. + And the reduction of highly dispersed CuO to Cu 0 The addition of CeO2 caused a second reduction peak to appear in the catalyst at around 238℃, and the overall reduction peak area increased. This second reduction peak belongs to the transformation of large CuO particles into Cu. 0 The reduction, combined with Cu in XRD 0 The diffraction peak signal becomes stronger ( Figure 7 The addition of CeO2 indicates that CuO accumulates on the catalyst surface, and the increase in reduction temperature suggests that CeO2 interacts with CuO, requiring a higher temperature for reduction. The addition of ZrO2 has a relatively small impact on the reducibility of the catalyst. XRD patterns show that the addition of ZrO2 increases the CuO concentration in the catalyst. 0Some aggregation occurred, but the reduction temperature did not increase, indicating a weak interaction between ZrO2 and CuO. The addition of Al2O3 significantly increased the reduction temperature, suggesting a strong interaction between Al2O3 and CuO. Furthermore, the reduction peak area decreased significantly, indicating that the addition of Al2O3 caused some aggregation of CuO, making it more difficult to reduce, thus reducing the amount of Cu in the reaction. 0 The addition of La2O3 reduced the ethanol conversion rate, which is consistent with our activity evaluation results. The addition of La2O3 also increased the reduction temperature of the catalyst, indicating a strong interaction with CuO. Notably, reduction peaks appeared at two different temperatures on this catalyst. The XRD pattern shows that the addition of La2O3 reduced the CuO concentration. 0 The significantly enhanced diffraction peaks indicate the presence of a large amount of CuO aggregates in the catalyst, which require higher temperatures to be reduced. This explains the low ethanol conversion rate exhibited by this catalyst.

[0189] NH3-TPD results and analysis of 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by precipitation-ammonia stripping method Figure 10 ).

[0190] Table 20 Acid site content of 10wt.% Cu-10wt.% M / SiO2 catalyst

[0191]

[0192]

[0193] NH3-TPD Results and Analysis: From Figure 10 As can be clearly seen in Table 20, the content of both weak acid and intermediate acid sites in the catalyst significantly increased after introducing other metal oxides. The Cu-La2O3 / SiO2 catalyst, which exhibits the best catalytic effect in isoprene formation, has a high content of weak acid sites and a moderate content of intermediate acid sites. Although the content of weak acid sites in the Cu-Al2O3 / SiO2 catalyst is similar to that in the Cu-La2O3 / SiO2 catalyst, it has more intermediate acid sites, resulting in poor catalytic performance. This indicates that a higher number of intermediate acid sites is detrimental to the further conversion of the intermediate products n-propanol and isobutylene to isoprene.

[0194] CO2-TPD results and analysis of 10wt.% Cu-10wt.% M / SiO2 catalyst prepared by precipitation-ammonia stripping method Figure 11 ).

[0195] Table 21. Base site content of 10wt.% Cu-10wt.% M / SiO2 catalyst

[0196]

[0197] Analysis of CO2-TPD characterization results: Figure 11 As shown in Table 21, the addition of oxides significantly enhanced the content of basic sites in the catalyst. The increase in total basic site content, from largest to smallest, is Al2O3 > La2O3 > ZrO2 > CeO2. The Cu-La2O3 / SiO2 catalyst, which exhibits the best catalytic effect in isoprene formation, has a large number of weak basic sites and a suitable amount of medium basic sites. Although the Cu-Al2O3 / SiO2 catalyst has the same content of weak basic sites as the Cu-La2O3 / SiO2 catalyst, it has a large number of medium basic sites, indicating that a large number of medium basic sites will reduce the catalytic effect. Therefore, a large number of weak basic sites and a suitable amount of medium basic sites can effectively improve the catalytic activity of the catalyst.

Claims

1. The application of a supported composite metal-oxide catalyst in the direct synthesis of high-carbon isoolefins from methanol and ethanol; wherein the high-carbon isoolefins are: isobutylene and isoprene; The supported composite metal-oxide catalyst consists of a silicon-based support, metallic Cu, and oxides; based on the total mass of the catalyst, the loading of metallic Cu is 0.1 ~ 30 wt.%; and the loading of oxides is 0 ~ 30 wt.%. in, The oxides are oxides of Ce, Zr, Al and / or La from the periodic table; Supported composite metal-oxide catalysts were prepared using a precipitation-ammonia stripping method, with the following steps: Metallic Cu precursor and oxide precursor were added to water and stirred to dissolve. Then, a silicon-based support was added and stirred to mix. Ammonia was added dropwise until the pH of the reaction solution was 12. The mixture was stirred for 8-12 h and heated to 90 °C to evaporate ammonia until the reaction solution was neutral. Then, it was heated to 120 °C to evaporate to dryness. The resulting solid was dried in an oven and then transferred to a muffle furnace and calcined at 450 °C for 4 h. After being removed, it was ground to obtain a supported composite metal-oxide catalyst. or, Supported composite metal-oxide catalysts were prepared using an ammonia stripping-impregnation method, with the following steps: (1) Add the metal Cu precursor to water, stir to dissolve, then add the silicon-based support, stir to mix, add ammonia dropwise until the pH of the reaction solution is 12, stir for 8~12 h, heat to 90 ℃ to evaporate ammonia until the reaction solution is neutral, then heat to 120 ℃ to evaporate to dryness, place the obtained solid material in an oven to dry, transfer to a muffle furnace and calcine at 450 ℃ for 4 h, take it out and grind it to obtain the supported metal Cu catalyst; (2) Add the supported metal Cu catalyst and oxide precursor obtained in step (1) to water, stir for 8-12 h, then heat to 120 °C to evaporate to dryness, place the obtained solid material in an oven to dry, transfer it to a muffle furnace to calcine at 450 °C for 4 h, take it out and grind it to obtain the supported composite metal-oxide catalyst.

2. The application as described in claim 1, characterized in that, Based on the total mass of the catalyst, the loading of metallic Cu is 1.0~20 wt.% and the loading of oxides is 1.0~20 wt.%.

3. The application as described in claim 1, characterized in that, The silicon-based support can be ordinary SiO2, gaseous SiO2, aerogel SiO2, ZSM-5, SBA-15, SBA-16, MCM-41, KIT-6, Y-type molecular sieve, MFI-type molecular sieve, Beta-type molecular sieve, column chromatography silica gel, mordenite, tuftite or chalcogenite.

4. The application as described in claim 1, characterized in that, The precursor of metallic Cu is selected from one or more of the following: Cu oxides, fluorides, chlorides, bromides, iodides, selenides, nitrates, sulfates, thiocyanates, phosphates, phosphites, pyrophosphates, carbonates, bicarbonates, acetylacetones, formates, acetates, acetates, butyrates, iodates, oxalates, citrates, gluconates, tartrates, fluoroborates, trifluoroacetates, tetrafluoroborates, chromites, perchlorates, glycinates, ethylenediaminetetraacetate, phthalocyanine compounds, and ethylenediamine dihydrogen phosphate compounds.

5. The application as described in claim 1, characterized in that, The oxide precursor is selected from one or more of the following: oxides, fluorides, chlorides, bromides, iodides, selenides, nitrates, sulfates, thiocyanates, phosphates, phosphites, pyrophosphates, carbonates, bicarbonates, acetylacetone salts, formates, acetates, butyrates, iodates, oxalates, citrates, gluconates, tartrates, fluoroborates, trifluoroacetates, tetrafluoroborates, chromites, perchlorates, glycinates, ethylenediaminetetraacetate, phthalocyanine compounds, and ethylenediamine dihydrogen phosphate compounds.

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