Method for activating fe-based catalysts of the mof structure and use thereof

Abstract

The present application relates to the technical field of catalyst preparation, in particular to a MOF structure Fe-based catalyst activation method, comprising the following steps: S1, placing Fe100Zr alpha A beta B gamma O delta catalyst in the constant temperature zone of a reactor, and purging the reactor system with inert gas; S2, switching the inert gas in S1 to reducing gas, wherein the reducing gas is a mixture of carbon monoxide and inert gas; S3, switching the reducing gas in S2 to inert gas; S4, switching the inert gas to active gas, wherein the active gas is a mixture of gaseous alkane with carbon atom number less than 5 and inert gas; S5, switching the active gas in S4 to inert gas, and after there is no active gas, switching the inert gas to synthesis gas, wherein the synthesis gas is a mixture of hydrogen, carbon monoxide and inert gas; the present application reduces the CO2 selectivity of the MOF structure Fe-based catalyst and improves the selectivity of low-carbon olefins.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, more particularly to a MOF structured Fe-based catalyst activation method and application thereof. BACKGROUND

[0002] Ethylene, propylene and butene (hereinafter referred to as: low carbon olefins) as an important basic raw material of petrochemical energy, at present its production mainly comes from petroleum steam cracking and catalytic cracking technology. Due to the distribution of resources in China, the development of non-petroleum route to prepare low carbon olefins is of great significance to China's energy security. In recent years, the process of synthesizing low carbon olefins from methanol has gradually matured, and has made great achievements in the industrialization process, while the process of synthesizing low carbon olefins from syngas (hereinafter referred to as: FTO) is still in the experimental research stage, but it has been widely concerned by countries around the world because of its short process route, low energy consumption, and wide raw material sources.

[0003] Although FTO process has many advantages, and has important strategic significance, application prospect and economic competitiveness for energy pattern. However, the development of high-efficiency catalyst in FTO process has become a key problem to be solved, and improving the active phase content and reaction performance is one of the most prominent key problems. We have sorted out the reported Fe-based FTO catalysts (Zhou et al., FTO reaction Fe-based catalyst activation and active phase research progress, DOI: 10.13550 / j.jxhg.20210868), and analyzed the active phase and non-active phase and their distribution. CN 113877582 A discloses a kind of hollow Fe2O3 microspheres, which are mixed with MOF (Fe) first, then a sugar solution is added, and then a Fe2O3 coated catalyst precursor is prepared by hydrothermal reaction, and finally a hollow Fe2O3 coated carbon catalyst is obtained by calcination. CN 110860316 A discloses a kind of VPO catalyst and activation atmosphere, which are respectively sent into the reactor through the feeder and the gas inlet, and then mixed at the inlet of multiple reaction tubes, realizing the simultaneous activation at different temperatures in multiple activation zones.

[0004] In recent years, although the synthesis of FTO catalyst has made considerable achievements, these works mainly focus on the preparation and synthesis of catalyst, and the research on catalyst activation and its influence on reaction performance needs to be further studied.

[0005] The prior art has the following defects:

[0006] (1) Poor reaction performance (including: low selectivity of low carbon olefins, low synergistic effect, high selectivity of CO2, etc.).

[0007] (2) The conventional catalyst activation is to calcine and reduce the catalyst, but the catalyst is not surface-modified and pre-implanted in the process. Therefore, the influence on the reaction performance of the catalyst is limited. SUMMARY

[0008] In order to solve the above technical problems in the prior art, the application provides a MOF structure Fe-based catalyst activation method. By introducing carbon-containing organic molecules and reducing gas into the bulk phase of the catalyst through MOF(Zr) and MOF(Fe) at high temperature reduction and calcination, the organic molecules in the MOF structure are decomposed and bulk carbon is implanted, so as to realize the generation of active phase FexC in the bulk phase of the catalyst, thereby reducing the CO2 selectivity of the catalyst. By means of introducing active gas, compared with the traditional reducing gas for reducing the catalyst, the active gas molecules can be implanted in the non-active phase FexC position on the surface phase of the catalyst, thereby improving the selectivity of low-carbon olefins of the catalyst.

[0009] The technical scheme of the application is as follows:

[0010] A MOF structure Fe-based catalyst activation method, comprising the following steps:

[0011] S1, Fe 100 Zr α A β B γ O δ The catalyst is placed in the constant temperature zone of the reactor, and the reactor system is purged with inert gas;

[0012] S2, the inert gas in S1 is switched to a reducing gas, and the reducing gas is a mixture of carbon monoxide and inert gas;

[0013] S3, the reducing gas in S2 is switched to inert gas;

[0014] S4, after the system in S3 is stable, the inert gas is switched to active gas, and the active gas is a mixture of gaseous alkane with carbon atom number less than 5 and inert gas;

[0015] S5, the active gas in S4 is switched to inert gas, and after the system is stable and there is no active gas, the inert gas is switched to synthesis gas, and the synthesis gas is a mixture of hydrogen, carbon monoxide and inert gas;

[0016] As a further technical scheme, in step S1, Fe 100 Zr α A β B γ O δ The MOF(Zr α) is one of Uio-66, Uio-66-NH2, MOF-801, MOF-808, NU-1000, MOF-867, PCN-777, MOF-545 or a mixture thereof.

[0017] As a further technical solution, in the step S1, Fe 100 Zr α A β B γ O δ MOF (Fe 100 ) of the catalyst is one of MIL-100, MIL-101, MIL-101-NH2, MIL-53, MIL-88 or a mixture thereof.

[0018] As a further technical solution, in the step S1, the pressure in the constant temperature zone of the reactor ranges from 0.5 MPa to 2 MPa.

[0019] As a further technical solution, in the step S2, the volume percentage of carbon monoxide is 10-50 vol%, the space velocity is 1000-5000 h -1 .

[0020] As a further technical solution, in the step S3, the temperature in the reactor ranges from 50 DEG C to 100 DEG C, and the pressure ranges from 2 MPa to 10 MPa.

[0021] As a further technical solution, in the step S4, the heating rate is 2-7 DEG C / min, and the reaction time ranges from 30 min to 120 min.

[0022] As a further technical solution, in the step S5, the pressure in the reactor ranges from 0.5 MPa to 2 MPa, the volume fraction of hydrogen and carbon monoxide is 10-50 vol%, the molar ratio of hydrogen to carbon monoxide is 1.5-2.5, and the space velocity is 1000-8000 h -1 .

[0023] As a further technical solution, in the steps S1, S3 and S5, the inert gas is one of nitrogen, argon and helium or a mixture thereof, and the space velocity is 100-2000 h-1.

[0024] Application of a method for activating a MOF structure Fe-based catalyst in a one-step synthesis gas method for low-carbon olefins

[0025] The technical solution of the present application has the beneficial effects of:

[0026] 1、The present application can realize the function of generating active phase FexC in the catalyst bulk phase to reduce the CO2 selectivity of the catalyst, compared with the traditional reducing gas reduced catalyst, by the method of introducing carbon-containing organic molecules into MOF(Zr) and MOF(Fe) in the catalyst bulk phase, and by the reduction of high-temperature reducing gas and the calcination effect to decompose and bulk-plant carbon in the organic molecules in the MOF structure.

[0027] 2、The present application can realize the function of implanting active gas molecules in the non-active phase FexC position on the catalyst surface phase to improve the low-carbon olefin selectivity of the catalyst, compared with the traditional reducing gas reduced catalyst, by the way of passing active gas after reduction of the reducing gas.

[0028] 3、The activation process of the present application is simple, and only needs to add several gas paths with cutoff function on the basis of the original equipment to realize the in-situ activation of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0029] The following shows the drawings of exemplary embodiments of the present application by way of example.

[0030] Figure 1 Fe for the present application 100 Zr x B y O z Catalyst in-situ activation process flow chart

[0031] Figure 2 Fe for the present application 100 Zr x B y O z SEM diagram of catalyst after in-situ activation

[0032] Figure 3 Fe for the present application 100 Zr x B y O z Catalyst stability test diagram DETAILED DESCRIPTION

[0033] The present application is further described below.

[0034] The existing one-step synthesis gas process for low-carbon olefin has the following problems: (1) poor reaction performance (including: low selectivity of low-carbon olefin, low synergistic effect, high CO2 selectivity, etc.); (2) conventional catalyst activation is to calcine and reduce the catalyst, and this process does not modify and pre-plant the catalyst surface, and has limited effect on the reaction performance of the catalyst.

[0035] The application can realize the generation of active phase FexC in the catalyst bulk phase to reduce the CO2 selectivity of the catalyst compared with the traditional reducing gas reduced catalyst by the method of introducing carbon-containing organic molecules into the MOF(Zr) and MOF(Fe) in the catalyst bulk phase, and by the reduction and calcination of high-temperature reducing gas, and decomposing and bulk carbon implanting the organic molecules in the MOF structure. Compared with the traditional reducing gas reduced catalyst, the active gas molecules can be implanted in the non-active phase FexC position on the catalyst surface phase by the way of passing the active gas after the reduction of the reducing gas, so as to improve the low carbon olefin selectivity of the catalyst.

[0036] The activation process of the application is simple, and only needs to add several gas paths with cutoff function on the basis of the original equipment to realize the in-situ activation of the catalyst.

[0037] As shown in Figure 1 The method for activating the MOF structure Fe-based catalyst of the application comprises the following steps:

[0038] S1, Fe 100 Zr α A β B γ O δ The catalyst is placed in the constant temperature zone of the reactor, and the reactor system is purged with inert gas;

[0039] S2, the inert gas in S1 is switched to a reducing gas, and the reducing gas is a mixture of carbon monoxide and inert gas;

[0040] S3, the reducing gas in S2 is switched to inert gas;

[0041] S4, after the system in S3 is stable, the inert gas is switched to active gas, and the active gas is a mixture of gaseous alkane with less than 5 carbon atoms and inert gas;

[0042] S5, the active gas in S4 is switched to inert gas, and after the system is stable and there is no active gas, the inert gas is switched to synthesis gas, and the synthesis gas is a mixture of hydrogen, carbon monoxide and inert gas;

[0043] Fe 100 Zr x B y O z The SEM diagram of the catalyst after in-situ activation is shown in Figure 2 .

[0044] Example 1

[0045] 1, Fe 100 Zr 100 K4(C9H6O6) 100O 202 The catalyst was placed in the constant temperature zone of the tubular reactor, and the tubular reactor system was purged with nitrogen (100%) at 1.0 MPa.

[0046] 2. Nitrogen (100 vol%) was switched to reduction gas (20 vol% carbon monoxide and 80 vol% nitrogen), and the temperature was raised to 600°C at a rate of 3°C / min, and held constant for 2-5 h.

[0047] 3. The reduction gas (20 vol% carbon monoxide and 80 vol% nitrogen) was switched to nitrogen (100 vol%), and the temperature of the tubular reactor was lowered to 100°C, and the pressure was raised to 2 MPa.

[0048] 4. After the system pressure and flow were stable, nitrogen (100 vol%) was switched to active gas (5 vol% propane and 95 vol% nitrogen), and the temperature was raised to 290°C at a rate of 5°C / min, and held constant for 1 h.

[0049] 5. The active gas (5 vol% propane and 95 vol% nitrogen) was switched to nitrogen (100 vol%), and the pressure was lowered to 1.0 MPa, and after the system was stable and free of active gas, the inert gas was switched to synthesis gas (10 vol% hydrogen, 20 vol% carbon monoxide, and 70 vol% nitrogen).

[0050] Example 2

[0051] 1. Fe 100 Zr 100 K4(C 24 H 12 O 13 Cl) 33.3 O 202 The catalyst was placed in the constant temperature zone of the tubular reactor, and the tubular reactor system was purged with nitrogen (100%) at 1.0 MPa.

[0052] 2. Nitrogen (100 vol%) was switched to reduction gas (20 vol% carbon monoxide and 80 vol% nitrogen), and the temperature was raised to 600°C at a rate of 3°C / min, and held constant for 2-5 h.

[0053] 3. The reduction gas (20 vol% carbon monoxide and 80 vol% nitrogen) was switched to nitrogen (100 vol%), and the temperature of the tubular reactor was lowered to 100°C, and the pressure was raised to 2 MPa.

[0054] 4. After the system pressure and flow rate are stable, switch the nitrogen (100 vol% in volume) to the active gas (5 vol% of propane in volume and 95 vol% of nitrogen in volume), and increase the temperature to 290°C at a rate of 5°C / min, and keep the temperature constant for 1 h.

[0055] 5. Switch the active gas (5 vol% of propane in volume and 95 vol% of nitrogen in volume) to the nitrogen (100 vol% in volume), and reduce the pressure to 1.0 MPa. After the system is stable and there is no active gas, switch the inert gas to the synthesis gas (10 vol% of hydrogen in volume, 20 vol% of carbon monoxide in volume, and 70 vol% of nitrogen in volume).

[0056] Example 3

[0057] 1. Fe 100 Zr 100 K4(C 24 H 16 O 32 ) 16.7 O 152 The catalyst is placed in the constant temperature zone of the tubular reactor, and the tubular reactor system is purged with nitrogen (100%) at 1.0 MPa.

[0058] 2. Switch the nitrogen (100 vol% in volume) to the reducing gas (20 vol% of carbon monoxide in volume and 80 vol% of nitrogen in volume), and increase the temperature to 600°C at a rate of 3°C / min, and keep the temperature constant for 2-5 h.

[0059] 3. Switch the reducing gas (20 vol% of carbon monoxide in volume and 80 vol% of nitrogen in volume) to the nitrogen (100 vol% in volume), and reduce the temperature of the tubular reactor to 100°C, and increase the pressure to 2 MPa.

[0060] 4. After the system pressure and flow rate are stable, switch the nitrogen (100 vol% in volume) to the active gas (5 vol% of propane in volume and 95 vol% of nitrogen in volume), and increase the temperature to 290°C at a rate of 5°C / min, and keep the temperature constant for 1 h.

[0061] 5. Switch the active gas (5 vol% of propane in volume and 95 vol% of nitrogen in volume) to the nitrogen (100 vol% in volume), and reduce the pressure to 1.0 MPa. After the system is stable and there is no active gas, switch the inert gas to the synthesis gas (10 vol% of hydrogen in volume, 20 vol% of carbon monoxide in volume, and 70 vol% of nitrogen in volume).

[0062] Example 4

[0063] 1, Fe 66.7 Zr 100 K4(C 48 H 64 O 16 N4Cl1Fe1) 33.3 O 102.1 The catalyst was placed in the constant temperature zone of the tubular reactor, and the tubular reactor system was purged with nitrogen (100%) at 1.0 MPa.

[0064] 2, nitrogen (100 vol%) was switched to reducing gas (20 vol% carbon monoxide, 80 vol% nitrogen), and the temperature was raised to 600°C at a rate of 3°C / min, and held constant for 2-5 h.

[0065] 3, the reducing gas (20 vol% carbon monoxide, 80 vol% nitrogen) was switched to nitrogen (100 vol%), and the temperature of the tubular reactor was lowered to 100°C, and the pressure was raised to 2 MPa.

[0066] 4, after the system pressure and flow were stable, nitrogen (100 vol%) was switched to active gas (5 vol% propane, 95 vol% nitrogen), and the temperature was raised to 290°C at a rate of 5°C / min, and held constant for 1 h.

[0067] 5, the active gas (5 vol% propane, 95 vol% nitrogen) was switched to nitrogen (100 vol%), and the pressure was lowered to 1.0 MPa, and after the system was stable and there was no active gas, the inert gas was switched to synthesis gas (10 vol% hydrogen, 20 vol% carbon monoxide, 70 vol% nitrogen).

[0068] Comparative Example

[0069] 1, Zr 100 Fe 100 K4O 352 The catalyst was placed in the constant temperature zone of the tubular reactor, and the tubular reactor system was purged with nitrogen (100%) at 1.0 MPa.

[0070] 2, nitrogen (100 vol%) was switched to reducing gas (20 vol% carbon monoxide, 80 vol% nitrogen), and the temperature was raised to 600°C at a rate of 3°C / min, and held constant for 2-5 h.

[0071] 3. Switch the reducing gas (20 vol% CO, 80 vol% N2) to N2 (100 vol%) and reduce the temperature of the tube reactor to 100°C and increase the pressure to 2 MPa.

[0072] 4. After the system pressure and flow rate are stable, switch the N2 (100 vol%) to the active gas (5 vol% C3H8, 95 vol% N2) and increase the temperature to 290°C at a rate of 5°C / min and maintain the temperature for 1 h.

[0073] 5. Switch the active gas (5 vol% C3H8, 95 vol% N2) to N2 (100 vol%) and reduce the pressure to 1.0 MPa. After the system is stable and there is no active gas, switch the inert gas to the synthesis gas (10 vol% H2, 20 vol% CO, 70 vol% N2).

[0074]

[0075]

[0076] Note: (1) Data taken from the results at 30 h; (2) The data listed in the table are based on carbon balance, and the specific calculation formula is as follows:

[0077] CO conversion:

[0078] Hydrocarbon selectivity:

[0079] C2 O -C4 O selectivity:

[0080] C2 P -C4 P selectivity:

[0081] C5 + selectivity:

[0082] In the formula, represents the carbon-containing molar number of the imported CO, and represents the carbon-containing molar number of CO and CO2 in the tail gas, i represents a specific carbon-containing hydrocarbon or CO2, and n (n = 1, 2, 3, 4) represents the stoichiometric number of carbon in the carbon-containing hydrocarbon or CO2.

[0083] As Figure 3Fe100ZrxByOz catalyst stability test plots for Example 1, Example 2, Example 3, Example 4, Comparative Example are shown.

[0084] It is to be understood that the application is by way of example only and that various changes and / or modifications and / or additions can be made thereto without departing from the spirit and scope of the application as outlined in the claims. Further, it is to be understood that the application can be carried out by specifically adapting the features and embodiments to the specific situation and materials without departing from the spirit and scope of the application. Accordingly, the application is not limited to that precisely as shown and described.

Claims

1. A method for activation of a MOF structured Fe-based catalyst, characterized in that, The method comprises the following steps: S1, Fe 100 Zr α A β B γ O δ The catalyst is placed in the thermostated zone of the reactor, the reactor system is purged with an inert gas. S2, switching the inert gas in S1 to a reducing gas, which is a mixture of carbon monoxide and inert gas; S3, switching the reducing gas in S2 to inert gas; S4, after the system is stable in S3, switching the inert gas to active gas, which is a mixture of gaseous alkane with carbon number less than 5 and inert gas; S5, switching the active gas in S4 to inert gas, after the system is stable without active gas, switching the inert gas to synthesis gas, which is a mixture of hydrogen, carbon monoxide and inert gas; In the step S4, the heating rate is 2-7 ℃ / min, and the reaction time is 30 min-120 min; The pressure in the reactor in the step S5 ranges from 0.5 MPa to 2 MPa, the volume fraction of the hydrogen and the carbon monoxide ranges from 10 vol% to 50 vol%, the molar ratio of the hydrogen to the carbon monoxide ranges from 1.5 to 2.5, and the space velocity ranges from 1000 h-1 to 8000 h-1. -1 ; In the step S1, Fe 100 Zr α A β B γ O δ The MOF of the catalyst is MOF(Zr α ) or MOF(Fe 100 ). The MOF(Zr) α The MOF(Fe) is one or a mixture of Uio-66, Uio-66-NH2, MOF-801, MOF-808, NU-1000, MOF-867, PCN-777, and MOF-545; 100 MIL-100, MIL-101, MIL-101-NH2, MIL-53, MIL-88, or a mixture thereof; The Fe 100 Zr α A β B γ O δ In the catalyst, A is K, B is C9H6O6, C 24 H 12 O 13 Cl 、 C 24 H 16 O 32 or C 48 H 64 O 16 N4Cl1Fe1.

2. The method of activating a MOF structured Fe-based catalyst according to claim 1, wherein, In the step S1, the pressure in the constant temperature zone of the reactor is 0.5-2 MPa.

3. The method of activating a MOF structured Fe-based catalyst according to claim 1, wherein, In the step S2, the volume percentage of carbon monoxide is 10 to 50 vol%, and the space velocity is 1000 to 5000 h -1 .

4. The method of activating a MOF structured Fe-based catalyst according to claim 1, wherein, In the step S3, the temperature in the reactor is 50-100 ℃, and the pressure is 2-10 MPa.

5. The method of activating a MOF structured Fe-based catalyst according to claim 1, wherein, In the steps S1, S3 and S5, the inert gas is one of nitrogen, argon and helium or a mixture thereof, and the space velocity is 100-2000h -1 .

6. Application of the method for activating MOF structure Fe-based catalyst in claim 1 in the synthesis gas one-step method for preparing low-carbon olefins.

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