Nitrogen-carbon modified catalyst for preparing butadiene from ethanol as well as preparation method and application of nitrogen-carbon modified catalyst

Abstract

The invention discloses a nitrogen-carbon modified catalyst for preparing butadiene from ethanol as well as a preparation method and application thereof, and belongs to the technical field of preparation of butadiene from ethanol. Two active components M1 and M2 are loaded in the catalyst, M1 is one or more than two of Cu, Zn, Ag, Cr and Co, M2 is one or more than two of Zr, Hf, Ta, Y, Sn and Nb in an oxidation state, and the total loading amount of the active metal M1 and M2 in the catalyst is greater than or equal to 0.1 wt%; the loading amounts of the nitrogen element and the carbon element in the catalyst are both greater than or equal to 0.1 wt%, the carrier is a silicon-based carrier, and the catalyst is obtained by co-dipping a soluble salt containing active components M1 and M2 and a solution of a soluble nitrogen carbon source in the silicon-based carrier, drying and roasting in inert gas, the catalyst disclosed by the invention shows ultrahigh activity and butadiene selectivity in a reaction for preparing butadiene from ethanol by a one-step method, the ethanol conversion rate reaches 90% or more, the butadiene selectivity reaches 70% or more, and the catalyst can stably run for 200 hours or more and has a very good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of preparing butadiene from ethanol, and specifically relates to a nitrogen-carbon modified ethanol-preparation butadiene catalyst, a preparation method thereof, and application in a one-step catalytic conversion reaction of ethanol to prepare butadiene. Background Art

[0002] 1,3-Butadiene (abbreviated as butadiene) is an important basic organic raw material for petrochemical industry and is widely used in the preparation of polymer products such as synthetic rubber and synthetic resin. With the acceleration of the global industrialization process, the demand for butadiene continues to grow, and the annual demand has reached tens of millions of tons, and has been rising year by year at a stable growth rate (Han Qiao, Tan Zhihe, Gao Yujian, et al. Research progress of catalysts for preparing 1,3-butadiene from ethanol [J]. Industrial Catalysis, 2024, 32(03): 1-8.). At present, the main source of butadiene is the separation of by-products in the process of producing ethylene by steam cracking of naphtha, which makes the output of butadiene highly dependent on the production scale of ethylene and the supply of cracking raw materials. However, with the increase in shale gas production, the composition of cracking raw materials has changed significantly, which has a significant impact on the output of butadiene. In view of this, exploring a sustainable and environmentally friendly butadiene production route has become an urgent problem to be solved.

[0003] The technology of converting ethanol to butadiene has a long history, dating back more than a century ago, and was once the dominant process for the industrial production of butadiene (Bin Samsudin I, Zhang H, Jaenicke S, Chuah GK. Recent Advances in Catalysts for the Conversion of Ethanol to Butadiene. Chemistry An Asian Journal. 2020; 15 (24): 4199-214.). As a biomass resource with abundant resources, low cost and environmental friendliness, ethanol is more in line with the carbon peak and carbon neutrality goals proposed by my country compared to non-renewable fossil resources. Therefore, using ethanol as a raw material to produce butadiene not only has broad market application prospects, but also has important scientific research value.

[0004] There are two main production processes for ethanol to butadiene, namely the one-step process and the two-step process. The one-step process refers to the use of only ethanol as raw material to produce butadiene in one step; while the two-step process refers to the use of ethanol and acetaldehyde as co-feed to produce butadiene. The one-step process has a low selectivity due to the synergistic effects of multiple active centers, including dehydrogenation, aldol condensation and dehydration, and the catalyst stability is far inferior to the two-step process due to the formation of carbon deposits and the agglomeration of dehydrogenation centers. The currently reported maximum stability of the one-step process is about 80 hours, and there is still a lot of room for improvement. Summary of the invention

[0005] The purpose of the present invention is to provide a nitrogen-carbon modified ethanol to butadiene catalyst and a preparation method thereof and an application in the one-step catalytic conversion of ethanol to butadiene reaction. The nitrogen-carbon modified catalyst prepared by the present invention can achieve high activity, high selectivity and high stability in the production of target product butadiene from ethanol, and the preparation method of the catalyst has the significant advantages of being cheap, simple and easy to operate and having strong universality.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] In the first aspect, the present invention provides a nitrogen-carbon modified ethanol to butadiene catalyst, wherein the catalyst is represented by the formula M1-M2 / NC@support, wherein M1 and M2 are both active components, M1 is one or more of Cu, Zn, Ag, Cr, and Co, and M2 is one or more of oxidized Zr, Hf, Ta, Y, Sn, and Nb, and the total loading amount of active metal elements M1 and M2 in the catalyst is ≥0.1wt%; NC represents nitrogen and carbon modification of the catalyst, the loading amount of nitrogen element in the catalyst is ≥0.1wt%, and the loading amount of carbon element in the catalyst is ≥0.1wt%; support is a silicon-based carrier.

[0008] Based on the above technical solution, further, the loading amount of M1 element in the catalyst is 0.1-25wt%; the loading amount of M2 element in the catalyst is 1-50wt%; the loading amount of nitrogen element in the catalyst is 1-15wt%; and the loading amount of carbon element in the catalyst is 0.5-25wt%.

[0009] Preferably, the loading amount of M1 element in the catalyst is 0.2-20wt%; the loading amount of M2 element in the catalyst is 1.5-30wt%; the loading amount of nitrogen element in the catalyst is 1.5-10wt%; and the loading amount of carbon element in the catalyst is 1.5-20wt%.

[0010] More preferably, the loading amount of M1 element in the catalyst is 0.4-10wt%; the loading amount of M1 element in the catalyst is 4-20wt%; the loading amount of nitrogen element in the catalyst is 2-8wt%; and the loading amount of carbon element in the catalyst is 2-15wt%.

[0011] Based on the above technical solution, further, the silicon-based carrier is a silicon-based molecular sieve or porous silica, the silicon-based molecular sieve includes one or more of SBA-15, SBA-16, silicate-1, deAl-beta, MCM-41, MWW, and NMSS; the porous silica includes one or more of white carbon black, silica sol, and mesoporous silica, and the specific surface area of ​​the porous silica is greater than 20m2 / g.

[0012] Based on the above technical scheme, further, the preparation method of the NMSS silicon-based molecular sieve is: add 90N100mL of a hexadecyltrimethylammonium chloride aqueous solution with a mass fraction of 15-35wt% to 120-180mL of ultrapure water, then add 0.5-0.9g of triethanolamine, stir evenly, and stir the resulting solution at 50-70°C for 0.5-5 hours; slowly add 50-100mL of a 10-30% by volume ethyl orthosilicate / cyclohexane solution, stir continuously at 60-80°C for 10-20 hours, remove the cyclohexane in the upper oil phase, heat to 90-95°C for aging for 2-5 hours, and the resulting solid is centrifuged, washed and dried, and then calcined at 600-700°C for 2-8h to obtain.

[0013] In a second aspect, the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps: impregnating a solution containing a soluble salt of active components M1 and M2 and a soluble nitrogen and carbon source into a silicon-based carrier, drying, and calcining in an inert gas at a calcination temperature of 350-750°C for 1-24 hours to obtain the catalyst.

[0014] Based on the above technical solution, further, the soluble salts of the active components M1 and M2 are one or more of the corresponding nitrates, chlorides, oxynitrates, oxychlorides, and organic alcohol salts.

[0015] Based on the above technical scheme, further, the nitrogen and carbon sources are one or more of urea, cyanamide, dicyandiamide, melamine, thiourea, isobutyramide, diformyl hydrazide, and dopamine.

[0016] Based on the above technical solution, further, the inert gas is one or more of nitrogen, argon and helium.

[0017] Based on the above technical solution, further, the drying temperature is 60-200° C., the roasting temperature is 500-600° C., and the roasting time is 2-6 hours.

[0018] In a third aspect, the present invention provides the use of the above catalyst in the one-step process for preparing butadiene from ethanol.

[0019] Based on the above technical solution, further, the reaction is carried out in a fixed bed reactor at normal pressure, and the reaction space velocity range is WHSV=0.12-10h -1 , using inert gas as carrier gas, carrier gas space velocity GSHV = 500-10000h -1 , the reaction temperature is 200-500℃.

[0020] Based on the above technical solution, further, the reaction temperature is 300-400°C, and the reaction space velocity range is WHSV=0.25-6h -1 The inert gas is one or more of nitrogen, argon and helium, and the carrier gas space velocity is 1000-5000h -1 .

[0021] Based on the above technical solution, further, during the reaction process, the ethanol conversion rate is 40-100%, and the 1,3-butadiene product selectivity is 50-80%.

[0022] The present invention has the following beneficial effects:

[0023] (1) The present invention adopts nitrogen-carbon modification to prepare a one-step ethanol to butadiene catalyst. The modified catalyst can achieve high activity, high selectivity, and high stability for ethanol and generate the target product butadiene. The catalyst carrier can also use different commercial carriers, and the catalyst reaction performance for different active components is also improved.

[0024] (2) The reaction stability of the catalyst for preparing butadiene from ethanol in one step prepared by the present invention is significantly improved, and is superior to all known catalysts reported so far.

[0025] (3) The catalyst of the present invention exhibits ultra-high activity and butadiene selectivity in the one-step ethanol to butadiene reaction, with an ethanol conversion rate of more than 90% and a butadiene selectivity of more than 70%. It can operate stably for more than 200 hours and has a good application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The stability investigation results of 0.5% Zn-4% Zr / NMSS are shown below;

[0027] Figure 2 These are the stability investigation results of 0.5% Zn-4% Zr / NC@NMSS. DETAILED DESCRIPTION

[0028] The following is further detailed description through specific embodiments.

[0029] Example 1

[0030] The preparation of Zn-Zr / NC@NMSS catalysts with different loading amounts includes the following steps:

[0031] (1) Synthesis method of carrier NMSS:

[0032] 96 mL of 25 wt% hexadecyltrimethylammonium chloride (CTAC) aqueous solution was added to 144 mL of ultrapure water, and then 0.72 g of triethanolamine (TEA) was added and stirred evenly. The resulting solution was transferred to a 500 mL round-bottom flask and slowly stirred in a 60°C oil bath for 1 hour. 80 mL of ethyl orthosilicate / cyclohexane (20 vol / vol%) solution was slowly added to the above solution. After continuous stirring for 12 hours under 75°C oil bath conditions, the cyclohexane solution in the upper oil phase was completely removed, and the temperature was raised to 90°C for aging for 3 hours. The above solid product was centrifuged and washed several times, and dried in an oven at 80°C overnight. The white solid obtained by calcining at 650°C in a muffle furnace for 4 hours was NMSS.

[0033] (2) Preparation of Zn-Zr / NC@NMSS catalysts with different loading amounts:

[0034] Different concentrations of zinc nitrate and zirconium oxynitrate were dissolved in water, and 1 g of urea was added, stirred and dissolved, and impregnated with the above-mentioned NMSS carrier at equal volume for 12 hours, wherein the loading amounts of Zn were selected as 0.5%, 1%, 2%, 5%, 10%, and 20%, respectively, and the loading amounts of Zr were selected as 2%, 4%, 8%, 12%, and 16% (all mass fractions), respectively. After drying at 80°C for 8 hours, the above samples were calcined in a tubular furnace at 550°C and 100 mL / min nitrogen atmosphere for 4 hours to obtain catalysts with different loading amounts.

[0035] Comparative Example 1

[0036] The preparation of Zn-Zr / NMSS catalyst comprises the following steps:

[0037] The synthesis method of the NMSS carrier is the same as that in Example 1, and then the aqueous solution of zinc nitrate and zirconium oxynitrate is impregnated with the carrier in equal volumes for 12 hours, wherein the loading amount of Zn is selected as 0.5%, and the loading amount of Zr is selected as 2%, 4%, 8%, 12%, and 16% (all mass fractions), respectively. After drying at 80°C for 8 hours, the above samples are calcined at 550°C in a muffle furnace for 4 hours to obtain Zn-Zr / C (@NMSS catalysts with different loading amounts.

[0038] Comparative Example 2

[0039] The preparation of Zn-Zr / C@NMSS catalyst includes the following steps:

[0040] (1) Synthesis method of carrier C@NMSS:

[0041] The preparation process is similar to the synthesis method of NMSS in Example 1, except that the last step is not calcined in a muffle furnace, but in a tube furnace at 300°C and 100 mL / min air atmosphere for 4 h to obtain a black solid named C@NMSS.

[0042] (2) Preparation of Zn-Zr / C@NMSS catalysts with different loading amounts:

[0043] The carrier C@NMSS was impregnated with an aqueous solution of zinc nitrate and zirconyl nitrate at equal volumes for 12 h, with a Zn loading of 0.5% and a Zr loading of 2% and 4%. After drying at 80 °C for 8 h, the samples were calcined in a tubular furnace at 550 °C and a nitrogen atmosphere of 100 mL / min for 4 h to obtain Zn-Zr / C@NMSS catalysts with different loading amounts.

[0044] Example 2

[0045] The preparation of NC-modified Zn-Zr-based catalysts with different types of supports includes the following steps:

[0046] The preparation process is similar to that of Example 1, with a Zn loading of 0.5% and a Zr loading of 2%. The difference is that the carrier is replaced with deAl-beta, MFI, MWW, SBA-15 and gas-phase SiO2, wherein the gas-phase SiO2 is purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and SBA-15 and MFI are purchased from Nankai Catalyst Factory. All of the above carriers are used directly after purchase without further treatment.

[0047] The synthesis method of MWW is as follows: deionized water, white carbon black, boric acid and piperidine (PI) are mixed and stirred evenly to form a synthetic gel with a composition of 1SiO2:1.4PI:1.33H3BO3:19H2O, and then placed in a rotary oven for crystallization at 130°C for 1 day, 150°C for 1 day, and 170°C for 5 days, and then the obtained sample is filtered, washed, dried at 80°C, and calcined at 550°C for 4h to obtain the MWW-B sample. Then the above MWW-B sample is mixed with 6mol / L nitric acid (solid-liquid ratio 1g / 20mL), refluxed at 100°C for 20h, then dried at 80°C, and calcined at 550°C for 4h, recorded as MWW.

[0048] The synthesis method of deAl-beta is as follows: a beta sample with a silicon-aluminum ratio of 12.5 was purchased from Nankai Catalyst Factory, and dealuminated. Beta was mixed with 16 mol / L nitric acid (solid-liquid ratio 1 g / 20 mL), refluxed at 80°C for 24 h, dried at 80°C, and calcined at 550°C for 4 h to obtain deAl-beta.

[0049] Comparative Example 3

[0050] The preparation of non-NC modified Zn-Zr based catalysts on different types of supports comprises the following steps:

[0051] The preparation process is similar to that of Example 2, except that urea is not added, and only zinc nitrate and zirconyl nitrate are added.

[0052] Example 3

[0053] The preparation of NC modified catalysts with different active components on the same carrier includes the following steps:

[0054] The preparation process is similar to that of Example 1, and the M1 metal precursors are copper nitrate (copper loading is 0.5%), silver nitrate (silver loading is 0.5%), and zinc nitrate (zinc loading is 0.5%), and the M2 metal precursors are zirconium oxynitrate (zirconium loading is 2%), hafnium chloride (hafnium loading is 2%), tantalum chloride (tantalum loading is 2%), and yttrium chloride (yttrium loading is 2%).

[0055] Comparative Example 4

[0056] Preparation of non-NC modified catalysts with different active components on the same carrier:

[0057] The preparation process is similar to that of Example 3, except that urea is not added.

[0058] Example 4

[0059] Evaluation process of ethanol to butadiene catalyst: 0.25 g of the catalyst prepared in the above example was pelletized and loaded into a fixed bed reactor, and the raw materials were brought into the reactor by pump feeding and carrier gas (flow rate of 40 mL / min). The ethanol feed rate of the reaction material was 0.005 ml / min, and the reaction space velocity was WHSV = 0.96 h -1 , the reaction temperature is 350℃.

[0060] Calculation method of reaction conversion rate and selectivity:

[0061] Ethanol conversion rate (%) = (n 反应前的乙醇 -n 反应后剩余乙醇 ) / n 反应前的乙醇 *100%

[0062] Butadiene selectivity (%) = 2n 产物中丁二烯 / (n 反应前的乙醇 -n 反应后剩余乙醇 )*100%

[0063] Example 5

[0064] The performance of the Zn-Zr / NC@NMSS catalyst with different loading amounts in Example 1 was evaluated. The reaction conditions were the same as in Example 4. The results are shown in Table 1.

[0065] Table 1 Catalytic performance of Zn-Zr / NC@NMSS catalysts with different loadings in Example 1

[0066]

[0067] It can be seen from the reaction results that when the Zn loading is fixed at 0.5%, the Zr loading is 2-8% and has relatively good catalytic performance. Among them, the active component Zr loading has better catalytic performance at 4%, and the butadiene selectivity can reach more than 70%. With the increase of Zr content, the conversion rate gradually increases and the butadiene selectivity gradually decreases.

[0068] Example 6

[0069] The performance of Zn-Zr / NMSS with different loading amounts in Comparative Example 1 was evaluated. The reaction conditions were the same as those in Example 4. The results are shown in Table 2.

[0070] Table 2 Catalytic performance of Zn-Zr / NMSS catalysts with different loadings in Comparative Example 1

[0071]

[0072] From the comparison of Tables 1-2, it can be seen that under the same Zr loading, the ethanol conversion rate and butadiene selectivity of the Zn-Zr / NC@NMSS catalyst of the present invention are higher than those of the catalyst without nitrogen and carbon modification, which illustrates the uniqueness and excellence of the present invention.

[0073] Example 7

[0074] The performance of the catalysts in Example 1 and Comparative Examples 1-2 was evaluated under the same reaction conditions as in Example 4. The results are shown in Table 3.

[0075] Table 3 Comparison of catalytic performance of the catalysts in Example 1 and Comparative Examples 1-2

[0076]

[0077] From the comparison of the performance of several catalysts in the table, it can be seen that under the same Zn and Zr loading, the ethanol conversion rate and butadiene selectivity of the catalyst modified by NC of the present invention are higher than those of the catalyst not modified by nitrogen and carbon and the catalyst only modified by C, and although the selectivity of butadiene for the catalyst modified by C is improved, the conversion rate is reduced, which shows the uniqueness and excellence of the NC modification strategy proposed in the present invention.

[0078] Example 8

[0079] In Example 2 and Comparative Example 3, at the same Zr and Zn loading, different carriers were replaced to evaluate the catalyst performance. The reaction conditions were the same as in Example 4. The results are shown in Table 4.

[0080] Table 4 Catalytic performance of catalysts with different carriers in Example 2 and Comparative Example 3

[0081]

[0082]

[0083] As can be seen from the table, the performance of catalysts supported on different silicon-based carriers after nitrogen-carbon modification is improved, which mainly reduces the selectivity of dehydration products such as ethylene, and improves the further conversion of the intermediate product acetaldehyde, thereby improving the selectivity of butadiene. In addition, the conversion rate of ethanol is also improved. In general, the strategy of NC modification is applicable to most silicon-based carrier systems and has universal applicability, reflecting the superiority and uniqueness of the present invention.

[0084] Example 9

[0085] The catalytic performance of 0.5% Zn-2% Zr / NC@NMSS at different reaction temperatures was investigated. The reaction space velocity and feed flow rate were the same as those in Example 4. The results are shown in Table 5.

[0086] Table 5 Catalytic performance of 0.5% Zn-2% Zr / NC@NMSS catalyst

[0087]

[0088] As can be seen from the table, the 0.5% Zn-2% Zr / NC@NMSS catalyst provided by the present invention can react at a relatively low temperature (275°C), and can ensure relatively high butadiene selectivity (>60%) and conversion rate (>50%) at above 350°C, and can even achieve 100% conversion at a relatively high selectivity (>60%) at a relatively high temperature, which reflects the superiority of the present invention.

[0089] Example 10

[0090] The catalytic performance of 0.5% Zn-2% Zr / NC@NMSS under different space velocity conditions was investigated. The reaction conditions were the same as those in Example 4, except that the reaction space velocity was changed. The results are shown in Table 6.

[0091] Table 6 Catalytic performance of 0.5% Zn-2% Zr / NC@NMSS catalyst

[0092] <![CDATA[WHSV(h -1 )]]> Ethanol conversion rate (%) Butadiene selectivity (%) 0.38 100 70 0.96 79 65 1.92 55 52 3.84 40 41

[0093] It can be seen from the data in the table that the catalyst provided by the present invention has good reaction performance at different reaction space velocities. -1 The best catalytic effect can be achieved.

[0094] Embodiment 11

[0095] The stability of 0.5% Zn-4% Zr / NMSS and 0.5% Zn-4% Zr / NC@NMSS was investigated. The reaction conditions were the same as those in Example 4. The results are shown in the attached Figure 1 and Figure 2 As can be seen from the figure, the conversion rate of 0.5% Zn-4% Zr / NMSS decreased from 75% to 65% within 120h, showing obvious deactivation, while 0.5% Zn-4% Zr / NC@NMSS not only had a higher conversion rate than 0.5% Zn4% Zr / NMSS, reaching more than 90%, but also maintained an ethanol conversion rate of more than 85% within 250h, and the butadiene selectivity was also maintained at more than 60%. This shows that the NC-modified catalyst is not only much more active than the unmodified catalyst, but also has a greatly improved stability, reflecting the superiority of the NC modification strategy.

[0096] In summary, the ethanol-to-butadiene catalyst prepared by the nitrogen-carbon modification strategy of urea-assisted pyrolysis in the present invention can achieve high activity, high selectivity and high stability in the preparation of butadiene, and this method is universal and suitable for most metal-silicon-based carrier systems. It can also be mass-produced and easy to apply industrially, and has broad application prospects.

Claims

1. A nitrogen-carbon modified ethanol to butadiene catalyst, characterized in that: The catalyst is represented by the formula M1-M2 / NC@support, wherein M1 and M2 are both active components, M1 is one or more of Cu, Zn, Ag, Cr, and Co, M2 is one or more of oxidized Zr, Hf, Ta, Y, Sn, and Nb, and the total loading of active metal elements M1 and M2 in the catalyst is ≥0.1wt%; NC represents nitrogen and carbon modification of the catalyst, the loading of nitrogen in the catalyst is ≥0.1wt%, and the loading of carbon in the catalyst is ≥0.1wt%; support is a silicon-based carrier.

2. The catalyst according to claim 1, characterized in that The loading amount of M1 element in the catalyst is 0.1-25wt%; the loading amount of M2 element in the catalyst is 1-50wt%; the loading amount of nitrogen element in the catalyst is 1-15wt% and the loading amount of carbon element in the catalyst is 0.5-25wt%.

3. The catalyst according to claim 2, characterized in that The loading amount of M1 element in the catalyst is 0.4-10wt%; the loading amount of M1 element in the catalyst is 4-20wt%; the loading amount of nitrogen element in the catalyst is 2-8wt%; and the loading amount of carbon element in the catalyst is 2-15wt%.

4. The catalyst according to claim 1, characterized in that The silicon-based carrier is a silicon-based molecular sieve or porous silica. The silicon-based molecular sieve includes one or more of SBA-15, SBA-16, silicate-1, deAl-beta, MCM-41, MWW, and NMSS; the porous silica includes one or more of white carbon black, silica sol, and mesoporous silica. The specific surface area of ​​the porous silica is greater than 20 m 2 / g; The preparation method of the NMSS silicon-based molecular sieve is as follows: 90-100 mL of a 15-35 wt% hexadecyltrimethylammonium chloride aqueous solution is added to 120-180 mL of ultrapure water, and then 0.5-0.9 g of triethanolamine is added, stirred evenly, and the resulting solution is stirred at 50-70° C. for 0.5-5 hours; 50-100 mL of a 10-30% by volume ethyl orthosilicate / cyclohexane solution is slowly added, and after continuous stirring at 60-80° C. for 10-20 hours, the cyclohexane in the upper oil phase is removed, the temperature is raised to 90-95° C. for aging for 2-5 hours, and the resulting solid is centrifuged, washed and dried, and then calcined at 600-700° C. for 2-8 hours to obtain.

5. The method for preparing the catalyst according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: impregnating a solution containing soluble salts of active components M1 and M2 and a soluble nitrogen and carbon source into a silicon-based carrier, drying the solution, and calcining the solution in an inert gas at a temperature of 350-750° C. for 1-24 hours to obtain the product.

6. The preparation method according to claim 5, characterized in that: The soluble salts of the active components M1 and M2 are one or more of the corresponding metal nitrates, chlorides, oxynitrates, oxychlorides, and organic alcohol salts; the nitrogen and carbon sources are one or more of urea, cyanamide, dicyandiamide, melamine, thiourea, isobutyramide, diformyl hydrazide, and dopamine; and the inert gas is one or more of nitrogen, argon, and helium.

7. The preparation method according to claim 5, characterized in that: The drying temperature is 60-200°C, the calcination temperature is 500-600°C, and the calcination time is 2-6 hours.

8. Use of the catalyst according to any one of claims 1 to 4 in the one-step process for preparing butadiene from ethanol, characterized in that: The reaction is carried out in a fixed bed reactor at atmospheric pressure, and the reaction space velocity range is WHSV = 0.12-10h -1 , using inert gas as carrier gas, carrier gas space velocity GSHV = 500-10000h -1 , the reaction temperature is 200-500℃.

9. The use according to claim 8, characterized in that: The reaction temperature is 300-400°C, and the reaction space velocity range is WHSV=0.25-6h -1 The inert gas is one or more of nitrogen, argon and helium, and the carrier gas space velocity is 1000-5000h -1 .

10. The use according to claim 8, characterized in that: During the reaction, the ethanol conversion rate is 40-100%, and the 1,3-butadiene product selectivity is 50-80%.

Images