A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 Methods for isomerizing olefins

Abstract

The present invention discloses a one-step method for preparing C 4‑7 The method for isomerizing olefins involves the activation of carbon dioxide molecules and the isomerization reaction of linear olefins. Specifically, the method is a method for producing isomerized olefins in a one-step process using carbon dioxide and hydrogen by coupling a linear olefin isomerization catalyst with a carbon dioxide hydrogenation catalyst under high temperature and high pressure conditions. By rationally optimizing the reaction conditions and the metal ratio in the catalyst, the method exhibits excellent isomerized olefin production performance, with a single-pass carbon dioxide conversion rate of up to 37% in a fixed bed, of which C 4‑7 The ratio of isoolefins to linear olefins is as high as 7. The advantages of the present invention are that the catalyst preparation process is simple and controllable, the equipment is simple, and it is easy to scale up industrially, and it can directly convert greenhouse gas carbon dioxide into high-value-added isoolefins.

Description

Technical Field

[0001] The present invention relates to the activation and utilization of carbon dioxide, and in particular to a one-step method for preparing carbon dioxide by catalytic hydrogenation. 4-7 A method for isomerizing olefins. Background Art

[0002] In the context of global carbon neutrality, the catalytic hydrogenation of CO2 to produce high-value-added products is of great significance. Isoolefins, such as isobutylene, are important chemical raw materials and intermediates. Isobutylene can be used to produce chemical products such as isobutanol and methyl tert-butyl ether. Isobutylene is also a high-performance gasoline additive. Isobutylene is primarily obtained from the C4 fraction produced by the steam cracking of naphtha to ethylene and from the catalytic cracking process. However, my country's petroleum resources are scarce. To date, research on the catalytic hydrogenation of CO2 has primarily focused on the production of linear olefins, alcohols, and aromatic compounds, with no reports on the production of isoolefins. Molecular sieves with acidic sites have a certain hydrogenation effect. The linear olefins generated by the reaction of CO2 and hydrogen over metal oxide catalysts can be easily hydrogenated to alkanes, isoalkanes, or benzene compounds. Therefore, the rational optimization of conditions and catalysts to produce isoolefins from CO2 hydrogenation in a one-step process is crucial for CO2 emission reduction and utilization. Summary of the Invention

[0003] The present invention aims to provide a one-step method for preparing C 4-7 A method for isomerizing olefins.

[0004] The specific technical solutions of the present invention are as follows:

[0005] A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 The method for isomerizing olefins is to couple a linear olefin isomerization catalyst with a carbon dioxide hydrogenation catalyst under high temperature and high pressure conditions to achieve a one-step preparation of C 4-7 Isoolefins.

[0006] Furthermore, the carbon dioxide catalytic hydrogenation one-step method is used to prepare C 4-7 The method for isomerizing olefins specifically comprises the following steps: first, in a fixed bed reactor, filling at least one of a molecular sieve or a metal-modified molecular sieve in a multi-bed mode, then filling with quartz wool and quartz sand as fillers, and finally filling with at least one of a metal oxide catalyst or a supported metal oxide catalyst with an alkali metal as a promoter; introducing hydrogen to carry out a reduction reaction, then cooling the metal catalyst bed and the molecular sieve catalyst bed respectively, and introducing a mixture of carbon dioxide and hydrogen to react to obtain C 4-7 Isoolefins.

[0007] Furthermore, the carbon dioxide hydrogenation catalyst for preparing linear olefins includes at least one of a metal oxide catalyst or a supported metal oxide catalyst with an alkali metal as a promoter; and the linear olefin isomerization catalyst includes at least one of a molecular sieve or a metal-modified molecular sieve.

[0008] Furthermore, the metal oxide includes at least one of Fe2O3, Fe4O3, and Co3O4.

[0009] Furthermore, the supported metal oxide catalyst is a metal supported on at least one carrier selected from oxides, carbides, carbon materials, carbon nanotubes, molecular sieves, and aerogels.

[0010] Furthermore, the alkali metal includes at least one of Li, Na, K, Rb, and Cs.

[0011] Furthermore, the molecular sieve includes at least one of HZSM-5, MOR, SAPO, and SiO2-Al2O3 aerogel.

[0012] Furthermore, the metal of the metal-modified molecular sieve is at least one of Cu, Zn, Ga, Fe, and Co.

[0013] Furthermore, the carbon dioxide accounts for 20%-70% of the total volume of carbon dioxide and hydrogen, and the remainder is hydrogen.

[0014] Furthermore, the high temperature and high pressure conditions are: pressure 1-8 MPa, reaction gas flow rate 10-200 mL / min, metal catalyst bed reaction temperature 250-400°C, molecular sieve bed reaction temperature 150-340°C; the reduction reaction temperature is 300°C-500°C, and the reduction time is 1-4h.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention shows excellent C 4-7 Catalytic performance of isoolefin synthesis. Under heating and pressurizing reaction conditions (metal catalyst bed 340℃, molecular sieve bed 240℃, 3MPa), C 4-7 The ratio of isomeric olefins to linear olefins is as high as 7.

[0017] (2) The raw gas used is carbon dioxide, which is of great significance to carbon neutrality and reduction of carbon dioxide emissions, and can save petroleum resources.

[0018] (3) Using a multi-bed method, isoolefins are prepared from raw gas in a one-step process, and the operation process is simple.

[0019] (4) The catalyst preparation process is simple and controllable, and can be easily scaled up industrially.

[0020] In summary, the multi-bed coupling method and catalyst provided by the present invention can efficiently convert the mixture of carbon dioxide and hydrogen into C 4-7 The catalyst has good catalytic stability and good industrial application prospects. DETAILED DESCRIPTION

[0021] The following examples illustrate the one-step method for preparing C by catalytic hydrogenation of carbon dioxide provided by the present invention. 4-7 The method and catalyst for isomerizing olefins are described in detail, but the present invention is not limited thereto. Meanwhile, the embodiments only provide some conditions for achieving this purpose, but do not mean that these conditions must be met to achieve this purpose.

[0022] Example 1

[0023] 50mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0024] Example 2

[0025] 100mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0026] Example 3

[0027] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0028] Example 4

[0029] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 150°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0030] Example 5

[0031] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 200°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0032] Example 6

[0033] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C over the metal catalyst bed and 340°C over the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 10mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0034] Example 7

[0035] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 1MPa, and the reaction was initiated at a flow rate of 30mL / min for 6-8 hours. After the reaction, the tube was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0036] Example 8

[0037] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 5MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0038] Example 9

[0039] 200mg of SiO2-Al2O3 aerogel was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 1.5%Na-Fe3O4 catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was increased to 3MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. After the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0040] Example 10

[0041] 200mg of HZSM-5 (Si / Al ratio 18) was weighed and loaded into the lower portion of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe₃O₄ catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H₂ / CO₂ ratio of 1-3. The pressure was raised to 5MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. Following the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were then analyzed quantitatively by gas chromatography. Specific reaction performance is listed in Table 1.

[0042] Example 11

[0043] 200mg of SAPO-34 was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe₃O₄ catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H₂ / CO₂ ratio of 1-3. The pressure was increased to 5MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. Following the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were then analyzed by gas chromatography for quantitative analysis. Specific reaction performance is listed in Table 1.

[0044] Example 12

[0045] 200mg of MOR was weighed and placed in the lower part of a quartz reaction tube, followed by quartz wool and quartz sand, and finally 100mg of 5K-Fe₃O₄ catalyst. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out at 400°C over the metal catalyst bed for 2 hours. The temperature was then lowered to 340°C for the metal catalyst bed and 250°C for the molecular sieve catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H₂ / CO₂ ratio of 1-3. The pressure was increased to 5MPa, and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. Following the reaction, the reaction was heated to 175°C in an insulated box and heated with a tape heater. The reaction products were then analyzed by gas chromatography for quantitative analysis. Specific reaction performance is listed in Table 1.

[0046] Comparative Example 1

[0047] 100mg of 5K-Fe3O4 catalyst was weighed into a quartz reaction tube. After the quartz reaction tube was mounted on a fixed-bed reactor, pure hydrogen was introduced at approximately 20mL / min. Reduction was carried out over the metal catalyst bed at 400°C for 2 hours. The temperature was then lowered to 340°C over the metal catalyst bed. The gas flow was switched to a mixture of carbon dioxide and hydrogen with an H2 / CO2 ratio of 1-3. The pressure was raised to 3MPa and the reaction was initiated at a flow rate of 20mL / min for 6-8 hours. Following the reaction, the reaction was heated to 175°C in an insulated oven and heated with tape heaters. The reaction products were then quantitatively analyzed by gas chromatography. Specific reaction performance is listed in Table 1.

[0048] Table 1

[0049]

[0050]

[0051] The catalytic performance evaluation results of the examples and comparative examples are shown in Table 1. The above results indicate that the preparation method of the examples of the present invention can exhibit excellent isoolefin preparation performance by rationally optimizing the reaction conditions and the ratio of metal catalyst to molecular sieve catalyst.

[0052] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 A method for isomerizing olefins, characterized in that: Under high temperature and high pressure conditions, the carbon dioxide hydrogenation catalyst for preparing linear olefins is coupled with a linear olefin isomerization catalyst to achieve a one-step preparation of C 4-7 Isoolefins; In a fixed bed reactor, a multi-bed model was used. First, 100 mg of SiO2-Al2O3 aerogel was filled, followed by quartz wool and quartz sand as fillers, and finally 100 mg of 5K-Fe3O4 catalyst was filled. Hydrogen was introduced for reduction reaction, and then the metal catalyst bed and the molecular sieve catalyst bed were cooled separately. A mixture of carbon dioxide and hydrogen was introduced, and C was obtained through high-temperature and high-pressure reaction. 4-7 Isoolefins; The carbon dioxide accounts for 25%-50% of the total volume of carbon dioxide and hydrogen, and the balance is hydrogen; The high temperature and high pressure conditions are: pressure 3 MPa, reaction gas flow rate 20 mL / min, metal catalyst bed reaction temperature 340°C, molecular sieve bed reaction temperature 250°C; the reduction reaction temperature is 400°C, and the reduction time is 2 h.

2. A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 A method for isomerizing olefins, characterized in that: Under high temperature and high pressure conditions, the carbon dioxide hydrogenation catalyst for preparing linear olefins is coupled with a linear olefin isomerization catalyst to achieve a one-step preparation of C 4-7 Isoolefins; In a fixed-bed reactor, a multi-bed model was used. First, 200 mg of SiO2-Al2O3 aerogel was filled, followed by quartz wool and quartz sand as fillers, and finally 100 mg of 5K-Fe3O4 catalyst was filled. Hydrogen was introduced for reduction reaction, and then the metal catalyst bed and the molecular sieve catalyst bed were cooled separately. A mixture of carbon dioxide and hydrogen was introduced, and C was obtained through high-temperature and high-pressure reaction. 4-7 Isoolefins; The carbon dioxide accounts for 25%-50% of the total volume of carbon dioxide and hydrogen, and the balance is hydrogen; The high temperature and high pressure conditions are: pressure 3 MPa, reaction gas flow rate 20 mL / min, metal catalyst bed reaction temperature 340°C, molecular sieve bed reaction temperature 250°C; the reduction reaction temperature is 400°C, and the reduction time is 2 h.

3. A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 A method for isomerizing olefins, characterized in that: Under high temperature and high pressure conditions, the carbon dioxide hydrogenation catalyst for preparing linear olefins is coupled with a linear olefin isomerization catalyst to achieve a one-step preparation of C 4-7 Isoolefins; In a fixed-bed reactor, a multi-bed model was used. First, 200 mg of SiO2-Al2O3 aerogel was filled, followed by quartz wool and quartz sand as fillers, and finally 100 mg of 1.5 Na-Fe3O4 catalyst was filled. Hydrogen was introduced for reduction reaction, and then the metal catalyst bed and the molecular sieve catalyst bed were cooled separately. A mixture of carbon dioxide and hydrogen was introduced, and C was obtained through high-temperature and high-pressure reaction. 4-7 Isoolefins; The carbon dioxide accounts for 25%-50% of the total volume of carbon dioxide and hydrogen, and the balance is hydrogen; The high temperature and high pressure conditions are: pressure 3 MPa, reaction gas flow rate 20 mL / min, metal catalyst bed reaction temperature 340°C, molecular sieve bed reaction temperature 250°C; the reduction reaction temperature is 400°C, and the reduction time is 2 h.

4. A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 A method for isomerizing olefins, characterized in that: Under high temperature and high pressure conditions, the carbon dioxide hydrogenation catalyst for preparing linear olefins is coupled with a linear olefin isomerization catalyst to achieve a one-step preparation of C 4-7 Isoolefins; In a fixed-bed reactor, a multi-bed model was used. First, 200 mg of HZSM-5 (Si / Al ratio 18) was filled, followed by quartz wool and quartz sand as fillers, and finally 100 mg of 5K-Fe3O4 catalyst was filled. Hydrogen was introduced for reduction reaction, and then the metal catalyst bed and the molecular sieve catalyst bed were cooled separately. A mixture of carbon dioxide and hydrogen was introduced, and C was obtained by high-temperature and high-pressure reaction. 4-7 Isoolefins; The carbon dioxide accounts for 25%-50% of the total volume of carbon dioxide and hydrogen, and the balance is hydrogen; The high temperature and high pressure conditions are: pressure 5 MPa, reaction gas flow rate 20 mL / min, metal catalyst bed reaction temperature 340°C, molecular sieve bed reaction temperature 250°C; the reduction reaction temperature is 400°C, and the reduction time is 2 h.

5. A one-step method for preparing C by catalytic hydrogenation of carbon dioxide 4-7 A method for isomerizing olefins, characterized in that: Under high temperature and high pressure conditions, the carbon dioxide hydrogenation catalyst for preparing linear olefins is coupled with a linear olefin isomerization catalyst to achieve a one-step preparation of C 4-7 Isoolefins; In a fixed bed reactor, 200 mg of MOR was first filled, followed by quartz wool and quartz sand as fillers, and finally 100 mg of 5K-Fe3O4 catalyst was filled in a multi-bed mode. Hydrogen was introduced for reduction reaction, and then the metal catalyst bed and the molecular sieve catalyst bed were cooled respectively, and a mixture of carbon dioxide and hydrogen was introduced. C 4-7 Isoolefins; The carbon dioxide accounts for 25%-50% of the total volume of carbon dioxide and hydrogen, and the balance is hydrogen; The high temperature and high pressure conditions are: pressure 5 MPa, reaction gas flow rate 20 mL / min, metal catalyst bed reaction temperature 340°C, molecular sieve bed reaction temperature 250°C; the reduction reaction temperature is 400°C, and the reduction time is 2 h.

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