A method for catalyzing the dehydrogenation of n-butane

Abstract

The application discloses a method for catalyzing a n-butane dehydrogenation reaction, and the method comprises the following steps: contacting a raw material containing n-butane and / or CO2 with a catalyst, and reacting to obtain a product containing butene and butadiene; the catalyst comprises a carrier and an active component loaded on the carrier; the active component comprises active component I and active component II; the active component I is cobalt; the active component II is at least one selected from manganese, molybdenum, tin, titanium, tungsten and aluminum; and the carrier is pure-silicon silicalite-1 and / or silicalite-2. The application solves the problems that the current n-butane dehydrogenation catalyst is easy to sinter and form carbon deposition, and the catalyst prepared based on the application has excellent butene and butadiene selectivity and catalytic stability in the n-butane dehydrogenation reaction, and has a good industrial application prospect.

Description

Technical Field

[0001] This application relates to a method for catalytic dehydrogenation of n-butane, belonging to the fields of nanomaterials and catalysis science. Background Technology

[0002] Against the backdrop of carbon emission reduction, the value-added and efficient utilization of low-carbon alkane resources has become particularly important and urgent. This application focuses on the high-value conversion of n-butane to produce the key chemicals butene and butadiene. Given the complex regeneration processes of existing industrial platinum-based catalysts and the environmental pollution posed by chromium-based catalytic systems, the development of environmentally friendly and inexpensive transition metal catalysts is crucial. However, transition metal catalysts often face problems such as sintering and coking; therefore, designing and preparing highly active, highly olefin-selective, and highly stable transition metal catalysts is currently a major challenge in the field of alkane dehydrogenation.

[0003] Taking advantage of the low cost, environmental friendliness, and high CH bond selectivity of cobalt-based catalysts, a highly dispersed and stable cobalt-based catalyst was prepared by using organic-assisted pyrolysis coupled with a composite oxide precursor. This solves the problems of easy sintering and coking of cobalt-based catalysts in the current n-butane dehydrogenation system.

[0004] The patents CN115920947A and CN114931968A have both involved hydrothermal synthesis processes, and the carriers used in patent CN111569937A are SAPO-34, 3A, 4A and 5A molecular sieves. Summary of the Invention

[0005] This application provides a supported cobalt-based catalyst, its preparation method, and its application in the n-butane dehydrogenation reaction. The interaction between cobalt and the guest metal oxide is enhanced by utilizing a guest metal oxide that can form a complex oxide with metallic cobalt, thereby improving the anti-sintering ability of the cobalt species. Coupled with an organic-assisted pyrolysis method, the dispersion of metallic cobalt is improved, resulting in a catalyst exhibiting excellent n-butane dehydrogenation activity, butene and butadiene selectivity, and catalytic stability.

[0006] In this application, silicalite-1 and silicalite-2 are used as supports to prepare highly dispersed and highly stable cobalt-based catalysts through organic-assisted pyrolysis and composite oxide precursors. The disclosed catalysts, preparation methods and applications exhibit different technical features and implementation effects from the aforementioned applications.

[0007] According to one aspect of this application, a method for catalytically dehydrogenating n-butane is provided, the method comprising:

[0008] A raw material containing n-butane, or a raw material containing n-butane and CO2, is contacted with a catalyst to react and obtain a product containing butene and butadiene.

[0009] Optionally, the catalyst includes a support and an active component supported on the support.

[0010] Optionally, the active component includes active component I and active component II.

[0011] Optionally, the active component I is cobalt; the active component II is selected from at least one of manganese, molybdenum, tin, titanium, tungsten, and aluminum.

[0012] Optionally, the carrier is pure silicon silicate-1 and / or silicate-2.

[0013] Optionally, the catalyst contains 0.01 to 10 wt% cobalt, wherein the cobalt content is based on the mass of cobalt element.

[0014] Optionally, the cobalt content is independently selected from any value among 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, and 10wt%, or a range between any two of the above points.

[0015] Optionally, the catalyst contains 0.1 to 20 wt% of active component II, wherein the content of active component II is based on the mass of the active component element.

[0016] Optionally, the content of active component II is independently selected from any value among 0.1wt%, 0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%, and 20wt%, or a range between any two of the above.

[0017] Optionally, the method for preparing the catalyst includes the following steps:

[0018] The catalyst is obtained by aging, drying, and calcining a mixture containing cobalt salt, active component II precursor, auxiliary pyrolysis organic matter, and support.

[0019] Optionally, the auxiliary pyrolysis organic compound is selected from at least one of oxalic acid, citric acid, isopropanol, ethylenediamine, triethanolamine, and ascorbic acid.

[0020] Optionally, the concentration of the auxiliary pyrolysis organic matter is 0.01–5 mol / L.

[0021] Optionally, the concentration of the auxiliary pyrolysis organic matter is independently selected from any value among 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, and 5 mol / L, or a range between any two of the above points.

[0022] Optionally, the molar ratio of the cobalt salt to the auxiliary pyrolysis organic matter is 100:1 to 1:10.

[0023] Optionally, the molar ratio of the cobalt salt to the auxiliary pyrolysis organic matter is independently selected from any value among 100:1, 90:1, 80:1, 70:1, 60:1, 50:1, 40:1, 30:1, 20:1, 10:1, 1:10 or a range between any two of the above.

[0024] Optionally, the precursor of active component II is selected from at least one of the chloride, nitrate, sulfate, and organic ester of active component II.

[0025] Optionally, the concentration of the active component II precursor is 0.01 to 10 mol / L, based on the molar amount of the active component II element in the active component II precursor.

[0026] Optionally, the concentration of the active component II precursor is independently selected from any value among 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, and 10 mol / L, or a range between any two of the above values.

[0027] Optionally, the molar ratio of the cobalt salt to the active component II precursor is 5:1 to 1:10.

[0028] Optionally, the molar ratio of the cobalt salt to the precursor of active component II is independently selected from any value among 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or a range between any two of the above.

[0029] Optionally, the cobalt salt is selected from at least one of cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt acetylacetonate.

[0030] Optionally, in the mixture, the concentration of the cobalt salt is 0.01 to 5 mol / L, based on the molar amount of cobalt in the cobalt salt.

[0031] Optionally, the cobalt salt concentration is independently selected from any value among 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.06 mol / L, 0.08 mol / L, 0.10 mol / L, 0.50 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, and 5 mol / L, or a range between any two of the above values.

[0032] Optionally, the mass percentage of the carrier to the mixture is 30 wt% to 70 wt%.

[0033] Optionally, the mass percentage of the carrier to the mixture is independently selected from any value among 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, or a range between any two of the above.

[0034] Optionally, the mixture may also include a solvent.

[0035] Optionally, the solvent is selected from at least one of water, methanol, and ethanol.

[0036] Optionally, the aging temperature is 10–80°C; the aging time is 30–1200 min.

[0037] Optionally, the aging temperature is independently selected from any value among 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, 70℃, and 80℃, or a range between any two of the above points.

[0038] Optionally, the aging time is independently selected from any value among 30 min, 60 min, 120 min, 180 min, 240 min, 300 min, 360 min, 420 min, 480 min, 540 min, 600 min, 660 min, 720 min, 780 min, 840 min, 900 min, 960 min, 1020 min, 1080 min, 1140 min, and 1200 min, or a range between any two of the above points.

[0039] Optionally, the drying temperature is 50–200°C; the drying time is 120–720 min.

[0040] Optionally, the drying temperature is independently selected from any value among 50°C, 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, 180°C, and 200°C, or a range between any two of the above points.

[0041] Optionally, the drying time is independently selected from any value among 120 min, 180 min, 240 min, 300 min, 360 min, 420 min, 480 min, 540 min, 600 min, 660 min, and 720 min, or a range between any two of the above points.

[0042] Optionally, the roasting temperature is 400–700°C; the roasting time is 30–360 min.

[0043] Optionally, the roasting temperature is independently selected from any value among 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, and 700℃, or a range between any two of the above points.

[0044] Optionally, the roasting time is independently selected from any value among 30 min, 60 min, 120 min, 180 min, 240 min, 300 min, and 360 min, or a range between any two of the above points.

[0045] Optionally, the reaction temperature is 500–650°C; the reaction pressure is 0.1–1.0 MPa.

[0046] Optionally, the temperature of the reaction is independently selected from any value among 500°C, 550°C, 600°C, and 650°C, or a range between any two of the above points.

[0047] Optionally, the pressure of the reaction is independently selected from any value of 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa or a range between any two of the above points.

[0048] Optionally, the volume ratio of CO2 to n-butane is 1:10 to 10:1; and the mass hourly space velocity (HHSV) of n-butane is 0.05 to 10.00 h⁻¹. -1 .

[0049] Optionally, the volume ratio of CO2 to n-butane is independently selected from any value among 1:10, 1:8, 1:6, 1:4, 1:2, 1:1, 2:1, 4:1, 6:1, 8:1, 10:1 or a range between any two of the above.

[0050] Optionally, the mass hourly space velocity (MSV) of the n-butane is independently selected from 0.05 h⁻¹. -1 0.1h -1 0.5h -1 1h -1 2h -1 3h -1 4h-1 5h -1 6h -1 7h -1 8h -1 9h -1 10h -1 Any value in the range or any two points mentioned above.

[0051] As an alternative technical solution, the catalyst of this application is prepared through the following technical solution:

[0052] The specific preparation method includes the following steps:

[0053] (1) Dissolve the precursors corresponding to cobalt salt and metal oxide in a solvent to prepare a homogeneous solution;

[0054] (2) Add the organic matter to (1) and stir to obtain a uniform impregnation solution;

[0055] (3) Add the carrier to (2) and stir evenly. The mixture is aged at a certain temperature for a certain time.

[0056] (4) Dry the mixture obtained in (3) at a certain temperature for a certain time, and then crush the dried sample;

[0057] (5) The powder sample obtained in (4) is calcined at a certain temperature to obtain the final catalyst.

[0058] Optionally, the metal oxide includes at least one of manganese oxide, molybdenum oxide, tin oxide, titanium oxide, tungsten oxide, and aluminum oxide.

[0059] Optionally, the organic compound includes at least one of oxalic acid, citric acid, isopropanol, ethylenediamine, triethanolamine, and ascorbic acid.

[0060] This application addresses the problems of sintering and carbon deposition in current n-butane dehydrogenation catalysts. The catalyst and its preparation method provided in this application utilize an organic-assisted cobalt salt pyrolysis coupled with a composite oxide precursor to obtain a cobalt-based catalyst resistant to sintering and coking. The catalyst comprises a support and active cobalt metal and metal oxide supported on the support, wherein the support is pure silicon silicate-1 and / or silicate-2. The catalyst prepared based on this application exhibits excellent butene and butadiene selectivity and catalytic stability in the n-butane dehydrogenation reaction, showing promising prospects for industrial application.

[0061] The beneficial effects that this application can produce include:

[0062] 1) The catalyst provided in this application, which is a cobalt-based catalyst prepared from an organic-assisted pyrolysis coupled composite oxide precursor, has good dispersibility and catalytic stability.

[0063] 2) This application primarily addresses the problems of sintering and carbon deposition of active metal components in current n-butane dehydrogenation systems. The cobalt-based catalyst prepared by this method exhibits excellent catalytic performance in the n-butane dehydrogenation reaction, with superior n-butane conversion, C4 olefin selectivity, and catalytic stability compared to traditional supported cobalt-based catalysts. Under conditions of 500–650 °C and 0.1–1.0 MPa, the single-pass conversion of n-butane exceeds 20%, and the C4 olefin selectivity reaches over 95%. The preparation method disclosed in this application is characterized by its simplicity and good reproducibility, and can be used for industrial applications in the n-butane dehydrogenation reaction. Attached Figure Description

[0064] Figure 1 This is a scanning electron microscope image of the sample from Example 1 of this application, with a scale bar of 100 nm. Detailed Implementation

[0065] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0066] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0067] This application uses a flame ionization detector (FID) to analyze hydrocarbon products in the product; and uses a thermal conductivity detector (TCD) to analyze H2, CO, CH4 and CO2 in the product.

[0068] The morphology and dimensions of the samples were characterized using a Hitachi SU1510 scanning electron microscope (low magnification, accelerating voltage: 15 kV). Prior to testing, the powder samples were adhered to conductive tape and sputter-coated with gold.

[0069] The conversion rate and selectivity calculation formulas in the embodiments of this application are as follows:

[0070]

[0071]

[0072] Example 1

[0073] First, 0.2469 g of Co(NO3)2·6H2O and 0.0950 g of SnCl2·2H2O were dissolved in 3 g of ethanol, and then 0.01 g of isopropanol was added and stirred until homogeneous. 5 g of pure silicalite-1 (S-1) support was added and stirred until homogeneous, then ethanol was added until adsorption saturation. The mixture was aged at 25 °C for 16 h, then dried at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain CoSnO. x / S-1 catalyst.

[0074] Figure 1 This is a scanning electron microscope (SEM) image of the sample from Example 1. Figure 1 It can be seen that CoSnO x The / S-1 catalyst uses plate-like cross-silicalite-1 with a particle size of 450 nm as a support, and the guest components in the catalyst are well dispersed.

[0075] Example 2

[0076] First, 0.2469 g of Co(NO3)2·6H2O and 0.1042 g of Al(NO3)3·9H2O were dissolved in 3 g of water, and then 0.0102 g of ethylenediamine was added and stirred until homogeneous. 5 g of pure silicalite-1 (S-1) support was added and stirred until homogeneous, then water was added until adsorption saturation. The mixture was aged at 25 °C for 16 h, then dried at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain CoAlO. x / S-1 catalyst.

[0077] Example 3

[0078] First, 0.2469 g of Co(NO3)2·6H2O and 0.0153 g of (NH4)2MoO4 were dissolved in 3 g of water, and then 0.0253 g of triethanolamine was added and stirred until homogeneous. 5 g of pure silicalite-1 (S-1) support was added and stirred until homogeneous, then water was added until adsorption saturation. The mixture was aged at 25 °C for 16 h, then dried at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain CoMoO4. x / S-1 catalyst.

[0079] Example 4

[0080] First, 0.2469 g of Co(NO3)2·6H2O and 0.0533 g of tetrabutyl titanate were dissolved in 3 g of ethanol, and then 0.0102 g of isopropanol was added and stirred until homogeneous. 5 g of pure silicalite-1 (S-1) support was added and stirred until homogeneous, then ethanol was added until adsorption saturation. The mixture was aged at 25 °C for 16 h, then dried at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain CoTiO2. x / S-1 catalyst.

[0081] Example 5

[0082] First, 0.2469 g of Co(NO3)2·6H2O and 0.0135 g of Na2(WO4)·2H2O were dissolved in 3 g of water, and then 0.0153 g of oxalic acid was added and stirred until homogeneous. 5 g of pure silicalite-1 (S-1) support was added and stirred until homogeneous, then water was added until adsorption saturation. The mixture was aged at 25 °C for 16 h, then dried at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain CoWO4. x / S-1 catalyst.

[0083] Comparative Example 1

[0084] First, 0.2469 g of Co(NO3)2·6H2O was dissolved in 3 g of ethanol, and 5 g of pure silicon S-1 support was added and stirred evenly. Ethanol was then added until adsorption saturation was achieved. The mixture was aged at 25 °C for 16 h, followed by drying at 80 °C for 360 min. The dried sample was then ground and crushed. After calcination at 400 °C for 360 min, the temperature was increased to 600 °C and calcined for another 30 min to finally obtain the Co / S-1 catalyst.

[0085] Test Example 1

[0086] The testing procedure was as follows: The catalysts from the examples and comparative examples were loaded into a fixed-bed reactor lined with a quartz tube and heated to the reaction temperature at a heating rate of 10°C / min under a nitrogen atmosphere (12 mL / min). Then, the reaction was switched to N2 / CO2 / n-C4H. 10 The reaction atmosphere was 9600 mL / (g·h) with a n-butane mass hourly space velocity of 0.62 h⁻¹. -1 CO2 / n-C4H 10 The ratio was 10:1, and the pressure was 0.1 MPa. The reaction products were heated and vaporized before being analyzed by gas chromatography. TCD was used to analyze H2, CO, CH4, and CO2 in the products. FID was used to analyze hydrocarbon products. Specific test results are shown in Table 1.

[0087] Table 1 shows the performance of the examples and comparative samples at 530℃ and 590℃. Compared to Co / S-1, CoSnO x / S-1、CoAlO x / S-1、CoMoO x / S-1 and CoTiO x The activity of all S-1 samples was improved to varying degrees. CoSnO x The n-butane conversion of Co / S-1 was significantly higher than that of Co / S-1 (59% vs 34%), and the selectivity for C4 olefins (monoolefins and butadiene) among hydrocarbon products was also higher than that of Co / S-1 (90.6% vs 86.3%). CoSnO xThe superior performance of / S-1 is mainly attributed to the fact that the guest tin oxide inhibits the aggregation and sintering of metallic cobalt, which slows down the catalyst deactivation rate and reduces side reactions such as cracking caused by metallic cobalt aggregation.

[0088] Table 1

[0089]

[0090]

[0091] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for catalytic dehydrogenation of n-butane, characterized in that, The method includes: A raw material containing n-butane and CO2 is contacted with a catalyst and reacted to obtain a product containing butene and butadiene. The catalyst is prepared by the following method: The catalyst is obtained by aging a mixture containing cobalt salt, active component II precursor, auxiliary pyrolysis organic matter, and support at 10-80℃ for 30-1200 min, drying at 50-200℃ for 120-720 min, and calcining at 400-700℃ for 30-360 min. The active component II is at least one of tin, molybdenum, and aluminum; The auxiliary pyrolysis organic compound is at least one of isopropanol, ethylenediamine, citric acid, and triethanolamine; The carrier is pure silicon silicate-1 and / or silicate-2.

2. The method according to claim 1, characterized in that, The catalyst contains 0.01 to 10 wt% cobalt, wherein the cobalt content is based on the mass of cobalt element. In the catalyst, the content of active component II is 0.1~20wt%, wherein the content of active component II is based on the mass of active component elements.

3. The method according to claim 1, characterized in that, The concentration of the auxiliary pyrolysis organic matter is 0.01~5 mol / L; The molar ratio of the cobalt salt to the auxiliary pyrolysis organic matter is 100:1 to 1:

10.

4. The method according to claim 1, characterized in that, The precursor of active component II is selected from at least one of the chloride, nitrate, sulfate, and organic ester of active component II.

5. The method according to claim 4, characterized in that, The concentration of the active component II precursor is 0.01~10 mol / L, based on the molar amount of the active component II element in the active component II precursor.

6. The method according to claim 4, characterized in that, The molar ratio of the cobalt salt to the precursor of active component II is 5:1 to 1:

10.

7. The method according to claim 4, characterized in that, The cobalt salt is selected from at least one of cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt acetylacetonate.

8. The method according to claim 4, characterized in that, In the mixture, the concentration of the cobalt salt is 0.01~5 mol / L, based on the molar amount of cobalt element in the cobalt salt.

9. The method according to claim 1, characterized in that, The mass percentage of the carrier to the mixture is 30wt% to 70wt%.

10. The method according to claim 9, characterized in that, The mixture also includes a solvent.

11. The method according to claim 10, characterized in that, The solvent is selected from at least one of water, methanol, and ethanol.

12. The method according to claim 1, characterized in that, The reaction temperature is 500~650 ℃; the reaction pressure is 0.1~1.0 MPa.

13. The method according to claim 1, characterized in that, The volume ratio of CO2 to n-butane is 1:10 to 10:1; the mass hourly space velocity (HHSV) of n-butane is 0.05 to 10.00 h⁻¹. -1 .

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