A two-stage rapid calcination method and system for a molecular sieve containing active metal

Abstract

The present invention discloses a two-stage rapid calcination method and system for molecular sieves containing active metals. The molecular sieve raw powder containing active metals and hot air enter a calcination furnace respectively for two-stage calcination. During the first-stage calcination, the volume fraction of oxygen in the hot air is 0-10%, and during the second-stage calcination, the volume fraction of oxygen in the hot air is 10-25%. After calcination, the gas-solid mixture enters a gas-solid separation unit for separation, and the separated solid is the calcination product. In the present invention, there is no local high temperature, the temperature field is uniform, the quality of the calcined product is good, and the performance is stable.

Description

Technical Field

[0001] The present invention relates to the field of preparation of catalytic materials, and particularly to a two-stage rapid calcination method and system for zeolite containing active metal. Background Art

[0002] Since the as-synthesized zeolite powder by hydrothermal synthesis needs to be calcined to remove the template agent in the pores to have the shape-selective catalytic function. During the calcination process of removing the template agent, the template agent is oxidized and burned, generating local high temperature, which will cause the collapse of the zeolite framework. For zeolites containing active metal, this phenomenon is more prominent. In addition to causing the collapse of the zeolite framework, it may also cause the active metal to detach from the framework, resulting in the decline of the catalytic performance of the zeolite. When a large number of zeolites are calcined industrially, a large amount of template agent accumulates and oxidizes and burns, and this situation is more likely to occur.

[0003] At present, the industrial calcination of zeolites mainly uses indirect heating rotary kilns, tunnel kilns and other calcination furnaces, and the calcination is carried out in an air atmosphere. In these calcination furnaces, the zeolites to be calcined will accumulate in some parts, and local aggregation and oxidation combustion of the template agent will occur during calcination, generating local high temperature. And because the zeolites usually stay in the furnace for a long time (sometimes up to several hours), it is easy to cause the collapse of the zeolite framework and the detachment of the active metal from the framework. For zeolites containing active metal, during the calcination process, it is necessary to consider both removing the template agent and ensuring the existence form and distribution position of the active metal species. Taking Cu-SSZ-13 as an example, the Cu species in the zeolite mainly include Cu 2+ 、Cu + 、[Cu(OH)] + 、CuO, etc. (Catalysis Science&Technology, 2020, 10(18): 6319-6329). Among them, Cu 2+ has the best SCR catalytic activity. In the conventional technical route, local high temperature easily converts the Cu species into CuO, resulting in a significant decline in its SCR catalytic activity.

[0004] Therefore, it is of great significance to develop a calcination technology for zeolites containing active metal with controllable temperature, no local high temperature and uniform temperature field. Summary of the Invention

[0005] The present invention provides a two-stage rapid calcination method and system for zeolite containing active metal with controllable temperature, no local high temperature and uniform temperature field. This method can ensure a uniform temperature field during calcination, avoid local high temperature, reduce the risk of zeolite framework collapse and active metal detachment from the framework, and maintain the stable catalytic performance of the zeolite.

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

[0007] A two-stage rapid calcination method for a molecular sieve containing active metals, comprising the following steps:

[0008] The molecular sieve raw powder containing active metals and hot air enter a calcination furnace respectively for two-stage calcination. During the first-stage calcination, the volume fraction of oxygen in the hot air is 0-10%, and during the second-stage calcination, the volume fraction of oxygen in the hot air is 10-25%. After calcination, the gas-solid mixture enters a gas-solid separation unit for separation, and the separated solid is the calcination product.

[0009] Furthermore, the molecular sieve is a molecular sieve having one or more structures among CHA, AEI, BEA, MFI, RTH, MOR and LTA structures.

[0010] Furthermore, the molecular sieve is SSZ-13 molecular sieve, SSZ-39 molecular sieve, MOR molecular sieve, Beta molecular sieve, ZSM-5 molecular sieve, SSZ-13 / MOR eutectic molecular sieve, Beta / MOR eutectic molecular sieve or ZSM-5 / MOR eutectic molecular sieve; the active metals are one or more of Fe, Cu, Mn, Ce, Ti and Zn.

[0011] Furthermore, the hot air is a gas at 350-900 °C generated by the combustion of combustible substances or obtained through indirect heat exchange; the temperature during the first-stage calcination is 330-800 °C, the temperature during the second-stage calcination is 350-850 °C, and the total time of the two-stage calcination is 0.01-10.00 minutes.

[0012] Furthermore, the flow rate of the hot air is 0.1-50 m / s; after calcination, the gas-solid mixture enters a gas-solid separation unit for separation, and the separated gas adopts one or several of high-temperature oxidation method, catalytic oxidation method and absorption and adsorption method.

[0013] The two-stage rapid calcination system for a molecular sieve containing active metals adopted by the method as described above includes a first gas unit, a molecular sieve raw powder bin, a first calcination furnace, a second gas unit and a first gas-solid separation unit;

[0014] Among them, a first-stage oxygen-deficient calcination zone and a second-stage oxidation calcination zone are arranged in the first calcination furnace;

[0015] The first gas unit, the molecular sieve raw powder bin and the second gas unit are connected to the inlet of the first calcination furnace, and the outlet of the first calcination furnace is connected to the inlet of the first gas-solid separation unit.

[0016] Furthermore, the first gas-solid separation unit is connected with a first tail gas treatment unit.

[0017] The two-stage rapid calcination system of molecular sieve containing active metal adopted by the method described above includes a first gas unit, a molecular sieve raw powder bin, a second calcination furnace, a first gas-solid separation unit, a third calcination furnace and a second gas-solid separation unit;

[0018] The first gas unit and the molecular sieve raw powder bin are connected to the inlet of the second calcination furnace. The first gas unit, the molecular sieve raw powder bin, and the outlet of the second calcination furnace are connected to the first gas-solid separation unit. The solid outlet of the first gas-solid separation unit is connected to the inlet of the third calcination furnace, and the outlet of the third calcination furnace is connected to the second gas-solid separation unit.

[0019] Furthermore, a third gas unit is also connected to the third calcination furnace; a second tail gas treatment unit is also connected to the second gas-solid separation unit.

[0020] Furthermore, a second cooler is provided between the third calcination furnace and the second gas-solid separation unit.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The present invention adopts a two-stage rapid calcination technology. In the first-stage oxygen-deficient calcination zone, the template agent inside the molecular sieve is rapidly removed without combustion. The removed template agent and its decomposition products are evenly dispersed in the gas-solid mixture. Since the first-stage oxygen-deficient calcination zone is in an oxygen-deficient atmosphere and there is insufficient oxygen to reach the combustion condition, it is ensured that the template agent and the template agent decomposition products do not burn, avoiding local high temperature. In the second-stage oxidation calcination zone, the residual carbon on the molecular sieve, the template agent and the template agent decomposition products in the mixed gas are oxidized. Since the molecular sieve, the escaped template agent and the template agent decomposition products are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field during calcination and avoiding local high temperature again, reducing the risk of molecular sieve framework collapse and active metal detachment from the framework, and maintaining the stable catalytic performance of the molecular sieve. There is no local high temperature and the temperature field is uniform in the present invention, and the quality of the calcined product is good and the performance is stable.

[0023] Furthermore, compared with the traditional calcination furnace that requires several hours, the residence time during calcination in the present invention is greatly shortened, which not only reduces the risk of active metal detachment from the framework due to the molecular sieve being in a high-temperature environment for a long time, but also reduces the system energy consumption.

[0024] Compared with the indirect heating of the traditional calcination furnace, in the present invention, calcination is carried out using a first calcination furnace provided with a first-stage oxygen-deficient calcination zone and a second-stage oxidation calcination zone, or using a connected second calcination furnace and third calcination furnace for calcination. The gas and solid are in direct contact for heat exchange, with a large contact area and high mass transfer and heat transfer efficiency, and can achieve rapid calcination in minutes or even seconds. Description of the Drawings

[0025] Figure 1Schematic diagram of the one - stage two - section rapid calcination process for molecular sieves;

[0026] Figure 2 Schematic diagram of the two - stage series rapid calcination process for molecular sieves;

[0027] Figure 3 For the products obtained by calcining the same molecular sieve raw powder by the method of Example 1 and the products obtained by calcining in a traditional rotary kiln at the same calcination temperature, the catalysts prepared under the same conditions, and NH 3 -SCR activity comparison diagram at different temperatures.

[0028] In the figure, 1 - First gas unit, 2 - Molecular sieve raw powder bin, 3 - First calcination furnace, 4 - Second gas unit, 5 - First cooler, 6 - First gas - solid separation unit, 7 - First tail gas treatment unit, 8 - Product bin, 9 - Second calcination furnace, 10 - First calcined powder bin, 11 - Third gas unit, 12 - Third calcination furnace, 13 - Second cooler, 14 - Second gas - solid separation unit, 15 - Second tail gas treatment unit. Detailed implementation mode

[0029] The present invention will be described in detail below with reference to the accompanying drawings.

[0030] A two - stage rapid calcination method for a molecular sieve containing active metal of the present invention includes the following steps:

[0031] The molecular sieve raw powder containing active metal and hot air at 350 - 900 °C are subjected to two - stage rapid calcination respectively. During the first - stage calcination, the volume fraction of oxygen is 0 - 10%, and during the second - stage calcination, the volume fraction of oxygen is 10 - 25%. After calcination, the gas - solid mixture is separated, the separated gas is subjected to tail gas treatment, and the separated solid is the calcined product.

[0032] Among them, the molecular sieve includes but is not limited to molecular sieves with CHA, AEI, BEA, MFI, RTH, MOR, and LTA structures. The molecular sieve containing active metal is especially single - crystal molecular sieves such as SSZ - 13, SSZ - 39, MOR, Beta, ZSM - 5, etc. containing at least one metal element of Fe, Cu, Mn, Ce, Ti, Zn, etc., or eutectic molecular sieves such as SSZ - 13 / MOR, Beta / MOR, ZSM - 5 / MOR, etc. The loading amount of the active metal does not affect the calcination effect in the present invention.

[0033] The hot air includes but is not limited to high - temperature gases generated by the combustion of combustible substances such as coal, oil, gas, and biomass, or high - temperature gases obtained through indirect heat exchange.

[0034] The flow rate of the hot air is 0.1 - 50 m / s.

[0035] The total time of the rapid two-stage roasting is 0.01 to 10.00 minutes, which is specifically related to the length of the roasting furnace.

[0036] The tail gas treatment method is one or more of high-temperature oxidation method, catalytic oxidation method, absorption and adsorption method, etc.

[0037] The two-stage roasting can be carried out in a single roasting furnace with two-stage roasting zones, or can be achieved by using two series-connected roasting furnaces.

[0038] The first-stage oxidation roasting in the present invention is oxygen-deficient roasting. In this stage, through rapid oxygen-deficient roasting, the template agent in the molecular sieve raw powder is removed, thereby solving the problem that the local high temperature caused by the oxidative combustion of the template agent leads to the collapse of the molecular sieve framework and the detachment of the active metal from the framework, resulting in the decline of the catalytic performance of the molecular sieve; however, in this oxygen-deficient roasting stage, the template agent inside the molecular sieve directly escapes or decomposes into small molecules and escapes under the action of high temperature. Since the template agent molecule contains more carbon and is in an oxygen-deficient atmosphere, carbon deposition will remain on the molecular sieve during its escape process. Therefore, a second-stage oxidation roasting is required.

[0039] When carrying out the second-stage oxidation roasting, by controlling the volume fraction of oxygen in the atmosphere, the residual carbon deposition generated in the first-stage oxygen-deficient roasting on the molecular sieve is oxidized and removed. Since the molecular sieve is evenly dispersed in the atmosphere, the heat released by the residual carbon deposition during the oxidation process is evenly dispersed in the atmosphere, ensuring a uniform temperature field during roasting, thereby avoiding local high temperature and protecting the active metal and the molecular sieve framework.

[0040] See Figure 1 , the system adopted by the two-stage rapid roasting method of the molecular sieve containing active metal in the present invention includes a first gas unit 1, a molecular sieve raw powder bin 2, a first roasting furnace 3, a second gas unit 4, a first gas-solid separation unit 6, a first tail gas treatment unit 7 and a product bin 8.

[0041] Among them, the first roasting furnace 3 is provided with a first inlet, a second inlet and a third inlet. The first gas-solid separation unit 6 is provided with a first outlet and a second outlet. The first roasting furnace 3 includes a first-stage oxygen-deficient roasting zone and a second-stage oxidation roasting zone.

[0042] The first gas unit 1 is connected to the first inlet of the first roasting furnace 3, the molecular sieve raw powder bin 2 is connected to the second inlet of the first roasting furnace 3, the second gas unit 4 is connected to the third inlet of the first roasting furnace 3, the outlet of the first roasting furnace 3 is connected to the inlet of the first gas-solid separation unit 6, the first outlet of the first gas-solid separation unit 6 is connected to the first tail gas treatment unit 7, and the second outlet of the first gas-solid separation unit 6 is connected to the product bin 8.

[0043] The first gas generated by the first gas unit 1, with a temperature of 350 - 900 °C, an oxygen volume fraction of 0 - 10%, and a flow rate of 0.1 - 50 m / s, enters the first inlet of the first roasting furnace 3. The molecular sieve raw powder provided by the molecular sieve raw powder bin 2 enters the second inlet of the first roasting furnace 3. The first gas and the molecular sieve raw powder are rapidly mixed and heat-exchanged in the first roasting furnace 3; the molecular sieve raw powder quickly reaches the roasting temperature of 330 - 800 °C and is first roasted in the first-stage oxygen-deficient roasting zone of the first roasting furnace 3, and the template agent inside the molecular sieve raw powder is quickly removed; the removed template agent and the template agent decomposition products are evenly dispersed into the gas-solid mixture composed of the first gas and the molecular sieve. Since the first-stage oxygen-deficient roasting zone is in an oxygen-deficient atmosphere and there is insufficient oxygen to reach the combustion condition, it ensures that the template agent and the template agent decomposition products do not burn, avoiding local high temperature, thereby protecting the active metal and the molecular sieve framework; however, in this section, due to the relatively high carbon content in the template agent molecules and the oxygen-deficient atmosphere, carbon deposition will remain on the molecular sieve during the process of its escape.

[0044] The second gas provided by the second gas unit 4 enters the third inlet of the first roasting furnace 3 and is quickly mixed with the gas-solid mixture coming out of the first-stage oxygen-deficient roasting zone and enters the second-stage oxidation roasting zone of the first roasting furnace 3 for rapid mixing, so that the oxygen volume fraction in the mixed gas in the second-stage oxidation roasting zone is 10% - 25%. At 350 - 850 °C, the residual carbon on the molecular sieve, the template agent and the template agent decomposition products in the mixed gas are oxidized; since the molecular sieve, the escaped template agent and the template agent decomposition products are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the first roasting furnace 3, thereby avoiding local high temperature and protecting the active metal and the molecular sieve framework. The gas-solid mixture coming out of the first roasting furnace 3 is cooled by the first cooler 5 (the first cooler 5 can be used or not used according to the material of the first gas-solid separation unit 6) and then enters the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the separated solid enters the product bin 8.

[0045] In the present invention, in addition to the first gas unit 1 and the second gas unit 4 that can provide the heat required for roasting, the first roasting furnace 3 itself can also provide heat.

[0046] See Figure 2 As shown in the figure, the above-mentioned two-stage rapid roasting method for the molecular sieve containing active metal can also adopt the following system, which includes a first gas unit 1, a molecular sieve raw powder bin 2, a second roasting furnace 9, a first cooler 5, a first gas-solid separation unit 6, a first tail gas treatment unit 7, a product bin 8, a first roasted powder bin 10, a third gas unit 11, a third roasting furnace 12, a second cooler 13, a second gas-solid separation unit 14 and a second tail gas treatment unit 15.

[0047] The second roasting furnace 9 is provided with a first inlet and a second inlet. The first gas-solid separation unit 6 is provided with a first outlet and a second outlet. The third roasting furnace 12 is provided with a first inlet and a second inlet.

[0048] The first gas unit 1 is connected to the first inlet of the second roasting furnace 9, the molecular sieve raw powder bin 2 is connected to the second inlet of the second roasting furnace 9, and the outlet of the second roasting furnace 9 is connected to the inlet of the first gas-solid separation unit 6 through the first cooler 5.

[0049] The gas outlet of the first gas-solid separation unit 6 is connected to the first tail gas treatment unit 7, the solid outlet of the first gas-solid separation unit 6 is connected to the inlet of the first roasted powder bin 10, the outlet of the first roasted powder bin 10 is connected to the first inlet of the third roasting furnace 12, the third gas unit 11 is connected to the second inlet of the third roasting furnace 12, the outlet of the third roasting furnace 12 is connected to the inlet of the second cooler 13 and the second gas-solid separation unit 14, the gas outlet of the second gas-solid separation unit 14 is connected to the second tail gas treatment unit 15, and the solid outlet of the second gas-solid separation unit 14 is connected to the product bin 8.

[0050] The first gas-solid separation unit 6 and the second gas-solid separation unit 14 are gas-solid separation units, which are one or a combination of a gravity settler, a cyclone separator, a porous ceramic filter dust collector, a metal powder sintered filter, an electrostatic separator and a bag filter.

[0051] Such as Figure 2As shown in the figure, the first gas generated by the first gas unit 1, with a temperature of 350 - 900°C, an oxygen volume fraction of 0 - 10%, and a flow rate of 0.1 - 50 m / s, enters the first inlet of the second roasting furnace 9. The molecular sieve raw powder provided by the molecular sieve raw powder bin 2 enters the second inlet of the second roasting furnace 9. The first gas and the molecular sieve raw powder are rapidly mixed and heat-exchanged in the second roasting furnace 9, and the molecular sieve raw powder quickly reaches the roasting temperature of 330 - 800°C for roasting, and the template agent inside the molecular sieve is rapidly removed; the removed template agent and the decomposition products of the template agent are evenly dispersed into the gas-solid mixture composed of the first gas and the molecular sieve. Since the roasting furnace is in a lean oxygen atmosphere and there is insufficient oxygen and the combustion condition is not reached, it is ensured that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperature, thus protecting the active metal; however, in this roasting furnace, since the template agent molecule contains more carbon and is in a lean oxygen atmosphere, carbon deposition will remain on the molecular sieve during its escape process. The gas-solid mixture coming out of the second roasting furnace 9 enters the first gas-solid separation unit 6 for gas-solid separation after being cooled by the first cooler 5 (the first cooler 5 is used or not used according to the temperature that the first gas-solid separation unit 6 can withstand). The separated gas enters the first tail gas treatment unit 7 for treatment, and high-value substances such as the template agent and partial decomposition products of the template agent in the tail gas are recovered. The separated solid enters the first roasted powder bin 10 to provide the first roasted powder for subsequent reactions.

[0052] The first roasted powder provided by the first roasted powder bin 10 enters the first inlet of the third roasting furnace 12. The third gas provided by the third gas unit 11, with a temperature of 350 - 900°C, an oxygen volume fraction of 10 - 25%, and a flow rate of 0.1 - 50 m / s, enters the second inlet of the third roasting furnace 12. The first roasted powder and the third gas are rapidly mixed and heat-exchanged in the third roasting furnace 12, and the first roasted powder is evenly dispersed into the third gas and quickly reaches the roasting temperature of 350 - 850°C for oxidative roasting to oxidize the residual carbon deposition on the molecular sieve; since the molecular sieve is evenly dispersed in the mixed gas, the heat released by the residual carbon deposition during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the third roasting furnace 12, thus avoiding local high temperature and protecting the active metal and the molecular sieve framework. The gas-solid mixture coming out of the third roasting furnace 12 enters the second gas-solid separation unit 14 for gas-solid separation after being cooled by the second cooler 13 (the second cooler 13 can be used or not used according to the material of the second gas-solid separation unit 14). The separated gas enters the second tail gas treatment unit 15 for treatment, and the separated solid enters the product bin 8.

[0053] In the above device, in addition to the first gas unit 1 and the third gas unit 11 that can provide the heat required for roasting, the second roasting furnace 9 and the third roasting furnace 12 themselves can also provide heat.

[0054] Example 1

[0055] The SSZ-13 molecular sieve has a CHA structure.

[0056] As Figure 1 shown, the natural gas hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 750 °C, an oxygen volume fraction of 0%, and a flow rate of 0.2 m / s for the system. The Cu-SSZ-13 molecular sieve raw powder provided by the molecular sieve raw powder bin 2 (the mass percentage of Cu loading is 3.5%) enters the first inlet and the second inlet of the first roasting furnace 3 respectively. The two are quickly mixed and heat-exchanged in the first roasting furnace; the molecular sieve raw powder quickly reaches the roasting temperature of 650 °C and is first roasted in the first-stage oxygen-deficient roasting zone of the first roasting furnace 3, and the template agent inside the molecular sieve is quickly removed; the removed template agent and the decomposition products of the template agent are evenly dispersed into the gas-solid mixture composed of the first gas and the molecular sieve. Since the first-stage inert roasting zone is in an inert atmosphere and lacks oxygen and cannot reach the combustion condition, it ensures that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperature, and the residence time of the molecular sieve in this roasting zone is only 1.5 minutes, thereby protecting the active metal and the molecular sieve framework; however, in this first-stage oxygen-deficient roasting zone, due to the relatively high carbon content in the template agent molecule and the oxygen-deficient atmosphere, carbon deposits will remain on the molecular sieve during its escape process.

[0057] The second gas, oxygen, provided by the second gas unit 4 is added to the third inlet of the first roasting furnace 3 and enters the second-stage oxidation roasting zone of the first roasting furnace 3 together with the gas-solid mixture coming out of the first-stage roasting zone for rapid mixing, so that the oxygen volume fraction in the mixed gas in this section is 19%. At the roasting temperature of 660 °C, the residual carbon on the molecular sieve, the template agent and the decomposition products of the template agent in the mixed gas are oxidized; since the molecular sieve, the escaped template agent and the decomposition products of the template agent are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the first roasting furnace 3, thereby avoiding local high temperature, and the residence time of the molecular sieve in the second-stage oxidation roasting zone is only 4 minutes, thereby protecting the active metal and the molecular sieve framework. The gas-solid mixture coming out of the first roasting furnace 3 is cooled by the first cooler 5 and then enters the first gas-solid separation unit 6, a bag filter, for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the separated solid Cu-SSZ-13 molecular sieve enters the product bin 8.

[0058] Figure 3 shown is the comparison between the product obtained by roasting the same molecular sieve raw powder by the method of Example 1 and the product obtained by roasting in a traditional rotary kiln at the same roasting temperature. For the catalysts prepared under the same conditions and the NH 3 -SCR activity comparison, it can be seen that the roasted product of Example 1 has a higher NH3 - The SCR activity is much higher at each temperature point because the molecular sieves to be calcined in the air atmosphere of the traditional rotary kiln calciner will aggregate at certain positions, which will cause local aggregation and oxidative combustion of the template agent during calcination, generating local high temperatures. Moreover, since the molecular sieves usually stay in the furnace for a long time (3 hours), it is easy to cause the collapse of the molecular sieve framework and the detachment of active metals from the framework, reducing the NH 3 - SCR activity of the molecular sieve; in addition, the Cu species in the molecular sieve mainly include Cu 2+ 、Cu + 、[Cu(OH)] + 、CuO, etc. Among them, Cu 2+ has the best SCR catalytic activity. In this traditional rotary kiln technical route, local high temperatures easily convert Cu species into CuO, resulting in a significant decline in its SCR catalytic activity. However, the present invention adopts a two-stage rapid calcination method for molecular sieves, with a short residence time (5.5 minutes), to rapidly remove the template agent inside the molecular sieve without combustion. The removed template agent and its decomposition products are uniformly dispersed into the gas-solid mixture, and the first-stage inert calcination zone is in an inert atmosphere with insufficient oxygen, not reaching the combustion condition, ensuring that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperatures, and thus protecting the active metal and the molecular sieve framework.

[0059] Example 2

[0060] The SSZ-13 molecular sieve has a CHA structure.

[0061] As Figure 1 shown, the fuel hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 725 °C, an oxygen volume fraction of 8%, and a flow rate of 5 m / s for the system. The first gas and the Fe-SSZ-13 molecular sieve raw powder (the mass percentage of Fe loading is 2.5%) provided by the molecular sieve raw powder bin 2 enter the first inlet and the second inlet of the first calciner 3 respectively, and the two are rapidly mixed and heat-exchanged in the first calciner; the molecular sieve raw powder quickly reaches the calcination temperature of 600 °C and is first calcined in the first-stage oxygen-deficient calcination zone of the first calciner 3, and the template agent inside the molecular sieve is rapidly removed; the removed template agent and the decomposition products of the template agent are uniformly dispersed into the gas-solid mixture composed of the first gas and the molecular sieve. Since this section is in an oxygen-deficient atmosphere with insufficient oxygen and does not reach the combustion condition, it ensures that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperatures, and the residence time of the molecular sieve in the first-stage oxygen-deficient calcination zone is only 0.06 minutes, thus protecting the active metal and the molecular sieve framework; however, in this section, due to the relatively high carbon content in the template agent molecules and the oxygen-deficient atmosphere, carbon deposits will remain on the molecular sieve during its escape.

[0062] The second gas, provided by the second gas unit 4, is introduced into the third inlet of the first roasting furnace 3. It enters the second oxidation roasting zone of the first roasting furnace 3 together with the gas-solid mixture coming out of the first-stage oxygen-deficient roasting zone for rapid mixing, so that the volume fraction of oxygen in the mixed gas in the second oxidation roasting zone is 16%. At the roasting temperature of 610 °C, the residual carbon deposits on the zeolite, the template agent and the template agent decomposition products in the mixed gas are oxidized. Since the zeolite, the escaped template agent and the template agent decomposition products are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the first roasting furnace 3, thus avoiding local high temperature. And the residence time of the zeolite in the second oxidation roasting zone is only 0.16 minutes, thereby protecting the active metal and the zeolite framework. The gas-solid mixture coming out of the first roasting furnace 3 directly enters the metal powder sintered filter of the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the separated solid Fe-SSZ-13 zeolite enters the product bin 8.

[0063] Example 3

[0064] Beta zeolite has a BEA structure.

[0065] As Figure 1 shown, the coal-fired hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 700 °C, a volume fraction of oxygen of 6%, and a flow rate of 40 m / s for the system. The first gas and the Fe-Beta zeolite raw powder (the mass percentage of Fe loading is 2.9%) provided by the zeolite raw powder bin 2 enter the first inlet and the second inlet of the first roasting furnace 3 respectively, and the two are rapidly mixed and heat-exchanged in the first roasting furnace; the zeolite raw powder quickly reaches the roasting temperature of 575 °C and is first roasted in the first-stage oxygen-deficient roasting zone of the first roasting furnace 3, and the template agent inside the zeolite is quickly removed; the removed template agent and the template agent decomposition products are evenly dispersed into the gas-solid mixture composed of the first gas and the zeolite. Since the first-stage oxygen-deficient roasting zone is in an oxygen-deficient atmosphere and there is insufficient oxygen to reach the combustion condition, it is ensured that the template agent and the template agent decomposition products do not burn, avoiding local high temperature. And the residence time of the zeolite in the first-stage oxygen-deficient roasting zone is only 0.008 minutes, thereby protecting the active metal and the zeolite framework; however, in this section, due to the relatively high carbon content in the template agent molecule and the oxygen-deficient atmosphere, residual carbon deposits will remain on the zeolite during its escape process.

[0066] The second gas, oxygen provided by the second gas unit 4, is added to the third inlet of the first roasting furnace 3 and enters the second-stage oxidation roasting zone of the first roasting furnace 3 together with the gas-solid mixture coming out of the first-stage oxygen-deficient roasting zone for rapid mixing, so that the volume fraction of oxygen in the mixed gas in the second-stage oxidation roasting zone is 24%. At a roasting temperature of 560 °C, the residual carbon deposits on the zeolite molecular sieve, the template agent in the mixed gas and the decomposition products of the template agent are oxidized; since the zeolite molecular sieve, the escaped template agent and the decomposition products of the template agent are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the first roasting furnace 3, thus avoiding local high temperature, and the residence time of the zeolite molecular sieve in the second-stage oxidation roasting is only 0.01 minute, thereby protecting the active metal and the zeolite molecular sieve framework. The gas-solid mixture coming out of the first roasting furnace 3 directly enters the porous ceramic filter dust collector of the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the separated solid Fe-Beta zeolite molecular sieve enters the product bin 8.

[0067] Example 4

[0068] The SSZ-13 / MOR eutectic zeolite molecular sieve has a CHA / MOR eutectic structure.

[0069] As Figure 2 shown, the natural gas hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 650 °C, a volume fraction of oxygen of 0%, and a flow rate of 10 m / s. The first gas and the Cu-SSZ-13 / Cu-MOR eutectic zeolite molecular sieve raw powder (the mass percentage of Cu loading is 4.5%) provided by the zeolite molecular sieve raw powder bin 2 enter the first inlet and the second inlet of the second roasting furnace 9 respectively. The two are quickly mixed and heat-exchanged in the second roasting furnace 9, and the zeolite molecular sieve raw powder quickly reaches the roasting temperature of 550 °C for roasting, and the template agent inside the zeolite molecular sieve is quickly removed; the removed template agent and the decomposition products of the template agent are evenly dispersed into the gas-solid mixture composed of the first gas and the zeolite molecular sieve. Since the inside of the second roasting furnace 9 is in an inert atmosphere and the oxygen is insufficient to reach the combustion condition, it is ensured that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperature, and the residence time of the zeolite molecular sieve in the second roasting furnace 9 is only 0.03 minute, thereby protecting the active metal and the zeolite molecular sieve framework; however, in this roasting furnace, due to the relatively high carbon content in the template agent molecule and the inert atmosphere, residual carbon deposits will remain on the zeolite molecular sieve during its escape process. The gas-solid mixture coming out of the second roasting furnace 9 directly enters the porous ceramic filter dust collector of the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and high-value-added substances such as the template agent and partial decomposition products of the template agent in the tail gas are recovered. The separated solid enters the first roasted powder bin 10.

[0070] The first calcined powder bin 10 supplies the first calcined powder, and the third gas unit 11 supplies the third gas with a temperature of 900 °C, an oxygen volume fraction of 21%, and a flow rate of 5 m / s. They enter the third calcination furnace 12 respectively. The two are quickly mixed and heat-exchanged in the third calcination furnace 12. The first calcined powder is evenly dispersed into the third gas and quickly reaches the calcination temperature of 615 °C for oxidative calcination to remove the residual carbon deposits on the zeolite molecular sieve. Since the zeolite molecular sieve is evenly dispersed in the mixed gas, the heat released by the residual carbon deposits during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the third calcination furnace 12, thus avoiding local high temperatures. Moreover, the residence time of the zeolite molecular sieve in this calcination furnace is only 0.06 minutes, thereby protecting the active metal and the zeolite framework. The gas-solid mixture coming out of the third calcination furnace 12 is cooled by the second cooler 13 and then enters the bag filter of the second gas-solid separation unit 14 for gas-solid separation. The separated gas enters the second tail gas treatment unit 15 for treatment, and the separated solid Cu-SSZ-13 / Cu-MOR eutectic zeolite molecular sieve enters the product bin 8.

[0071] Example 5

[0072] The SSZ-39 zeolite molecular sieve has an AEI structure.

[0073] As Figure 1 shown, the fuel hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 350 °C, an oxygen volume fraction of 10%, and a flow rate of 0.1 m / s for the system. The first gas and the Cu-SSZ-39 zeolite molecular sieve raw powder (the mass percentage of Cu loading is 3%) supplied by the zeolite molecular sieve raw powder bin 2 enter the first inlet and the second inlet of the first calcination furnace 3 respectively. The two are quickly mixed and heat-exchanged in the first calcination furnace. The zeolite molecular sieve raw powder quickly reaches the calcination temperature of 330 °C and is first calcined in the first-stage oxygen-deficient calcination zone of the first calcination furnace 3, and the template agent inside the zeolite molecular sieve is quickly removed. The removed template agent and the decomposition products of the template agent are evenly dispersed into the gas-solid mixture composed of the first gas and the zeolite molecular sieve. Since this section is in an oxygen-deficient atmosphere and there is insufficient oxygen to reach the combustion condition, it is ensured that the template agent and the decomposition products of the template agent do not burn, avoiding local high temperatures. Moreover, the residence time of the zeolite molecular sieve in the first-stage oxygen-deficient calcination zone is only 6 minutes, thereby protecting the active metal and the zeolite framework. However, in this section, since the template agent molecule contains more carbon and is in an oxygen-deficient atmosphere, residual carbon deposits will remain on the zeolite molecular sieve during its escape process.

[0074] The second gas provided by the second gas unit 4 is added to the third inlet of the first roasting furnace 3, and enters the second-stage oxidation roasting zone of the first roasting furnace 3 together with the gas-solid mixture coming out of the first-stage oxygen-deficient roasting zone for rapid mixing, so that the volume fraction of oxygen in the mixed gas in the second-stage oxidation roasting zone is 25%. At the roasting temperature of 850 °C, the residual carbon deposits on the zeolite molecular sieve, the template agent and the template agent decomposition products in the mixed gas are oxidized; since the zeolite molecular sieve, the escaped template agent and the template agent decomposition products are evenly dispersed in the mixed gas, the heat released by these substances during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the first roasting furnace 3, thus avoiding local high temperature, and the residence time of the zeolite molecular sieve in the second-stage oxidation roasting zone is only 4 minutes, thereby protecting the active metal and the zeolite framework. The gas-solid mixture coming out of the first roasting furnace 3 directly enters the metal powder sintering filter of the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the separated solid Cu-SSZ-39 zeolite molecular sieve enters the product bin 8.

[0075] Example 6

[0076] The SSZ-13 / MOR eutectic zeolite molecular sieve has a CHA / MOR eutectic structure.

[0077] As Figure 2 shown, the natural gas hot blast stove serves as the first gas unit 1, and the hot flue gas it generates provides the first gas with a temperature of 900 °C, an oxygen volume fraction of 2%, and a flow rate of 50 m / s. The first gas and the Fe-SSZ-13 / Fe-MOR eutectic zeolite molecular sieve raw powder (the mass percentage of Fe loading is 1.6%) provided by the zeolite molecular sieve raw powder bin 2 enter the first inlet and the second inlet of the second roasting furnace 9 respectively. The two are rapidly mixed and heat exchanged in the second roasting furnace 9, and the zeolite molecular sieve raw powder quickly reaches the roasting temperature of 800 °C for roasting, and the template agent inside the zeolite molecular sieve is quickly removed; the removed template agent and the template agent decomposition products are evenly dispersed into the gas-solid mixture composed of the first gas and the zeolite molecular sieve. Since the inside of the second roasting furnace 9 is in an inert atmosphere and the oxygen is insufficient to reach the combustion condition, it is ensured that the template agent and the template agent decomposition products do not burn, avoiding local high temperature, and the residence time of the zeolite molecular sieve in the second roasting furnace 9 is only 0.007 minutes, thereby protecting the active metal and the zeolite framework; however, in this roasting furnace, due to the relatively high carbon content in the template agent molecule and the inert atmosphere, carbon deposits will remain on the zeolite molecular sieve during its escape process. The gas-solid mixture coming out of the second roasting furnace 9 directly enters the porous ceramic filter cartridge dust collector of the first gas-solid separation unit 6 for gas-solid separation. The separated gas enters the first tail gas treatment unit 7 for treatment, and the high-value substances such as the template agent and the partially decomposed products of the template agent in the tail gas are recovered. The separated solid enters the first roasting powder bin 10.

[0078] The first calcined powder in the first calcined powder bin 10 and the third gas provided by the third gas unit 11 with a temperature of 500 °C, an oxygen volume fraction of 21%, and a flow rate of 5 m / s respectively enter the third calcination furnace 12. The two are rapidly mixed and heat-exchanged in the third calcination furnace 12. The first calcined powder is evenly dispersed into the third gas and quickly reaches the calcination temperature of 350 °C for oxidative calcination to remove the residual carbon deposits on the zeolite. Since the zeolite is evenly dispersed in the mixed gas, the heat released by the residual carbon deposits during the oxidation process is evenly dispersed in the mixed gas, ensuring a uniform temperature field in the third calcination furnace 12, thereby avoiding local high temperatures. Moreover, the residence time of the zeolite in this calcination furnace is only 0.003 minutes, thus protecting the active metal and the zeolite framework. The gas-solid mixture coming out of the third calcination furnace 12 is cooled by the second cooler 13 and then enters the bag filter of the second gas-solid separation unit 14 for gas-solid separation. The separated gas enters the second tail gas treatment unit 15 for treatment, and the separated solid Fe-SSZ-13 / Fe-MOR eutectic zeolite enters the product bin 8.

[0079] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it should not be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. A two-stage rapid calcination method for molecular sieves containing active metals, characterized in that, it includes the following steps: The molecular sieve raw powder containing active metals and hot air enter the calcination furnace respectively for two-stage calcination. During the first-stage calcination, the volume fraction of oxygen in the hot air is 0%, and the template agent and the decomposition products of the template agent inside the molecular sieve do not burn; during the second-stage calcination, the volume fraction of oxygen in the hot air is 10-25%, and after calcination, the gas-solid mixture enters the gas-solid separation unit for separation, and the separated solid is the calcination product; the hot air is a gas at 350-900 °C generated by the combustion of combustible substances or obtained through indirect heat exchange; The active metal is one or more of Fe, Cu, Mn, Ce, Ti and Zn; During the first-stage calcination, the temperature is 330-800 °C, and during the second-stage calcination, the temperature is 350-850 °C; The molecular sieve is a molecular sieve having one or more structures among CHA, AEI, BEA, MFI, RTH, MOR and LTA structures; The total time of the two-stage calcination is 0.01-10.00 minutes.

2. The two-stage rapid calcination method for molecular sieves containing active metals according to claim 1, characterized in that, The molecular sieve is SSZ-13 molecular sieve, SSZ-39 molecular sieve, MOR molecular sieve, Beta molecular sieve, ZSM-5 molecular sieve, SSZ-13 / MOR eutectic molecular sieve, Beta / MOR eutectic molecular sieve or ZSM-5 / MOR eutectic molecular sieve.

3. The two-stage rapid calcination method for molecular sieves containing active metals according to claim 1, characterized in that, The flow rate of the hot air is 0.1-50 m / s; after calcination, the gas-solid mixture enters the gas-solid separation unit for separation, and the separated gas is treated by one or several of high-temperature oxidation method, catalytic oxidation method and absorption and adsorption method.

4. The two-stage rapid calcination system for molecular sieves containing active metals adopted by the method of claim 1, characterized in that, it includes a first gas unit (1), a molecular sieve raw powder bin (2), a first calcination furnace (3), a second gas unit (4) and a first gas-solid separation unit (6); Among them, a first-stage oxygen-deficient calcination zone and a second-stage oxidation calcination zone are arranged in the first calcination furnace (3); The first gas unit (1), the molecular sieve raw powder bin (2) and the second gas unit (4) are connected to the inlet of the first calcination furnace (3), and the outlet of the first calcination furnace (3) is connected to the inlet of the first gas-solid separation unit (6); the first gas-solid separation unit (6) is connected with a first tail gas treatment unit (7).

5. The two-stage rapid calcination system for molecular sieves containing active metals adopted by the method of claim 1, characterized in that, it includes a first gas unit (1), a molecular sieve raw powder bin (2), a second calcination furnace (9), a first gas-solid separation unit (6), a third calcination furnace (12) and a second gas-solid separation unit (14); The first gas unit (1) and the molecular sieve raw powder silo (2) are connected to the inlet of the second roasting furnace (9). The outlet of the first gas unit (1), the molecular sieve raw powder silo (2), and the second roasting furnace (9) is connected to the first gas-solid separation unit (6). The solid outlet of the first gas-solid separation unit (6) is connected to the inlet of the third roasting furnace (12). The outlet of the third roasting furnace (12) is connected to the second gas-solid separation unit (14); The third roasting furnace (12) is further connected to a third gas unit (11); the second gas-solid separation unit (14) is further connected to a second tail gas treatment unit (15); a second cooler (13) is provided between the third roasting furnace (12) and the second gas-solid separation unit (14).

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