Device and method for producing olefin through negative pressure driven catalytic alkane dehydrogenation

Abstract

The invention provides a device and a method for producing olefin through negative pressure driven catalysis of alkane dehydrogenation. A reaction unit comprises a pre-lifting zone, an oil agent contact zone, a reaction zone, a product quenching zone, a reaction outlet zone, an oil agent separation zone and a steam stripping zone; the device further comprises a negative pressure driving device, a spent catalyst receiver and a regenerant receiver; an oil-gas outlet of the oil-agent separation zone is communicated with an oil-gas inlet of the negative pressure driving device, and a catalyst outlet of the oil-agent separation zone is communicated with a catalyst inlet of the steam stripping zone; a catalyst outlet of the steam stripping area is communicated with a catalyst inlet of a spent catalyst receiver, and a catalyst outlet of the spent catalyst receiver is communicated with a spent catalyst inlet of the regeneration unit; a regenerated catalyst outlet of the regeneration unit is communicated with a catalyst inlet of a regenerant receiver, and a catalyst outlet of the regenerant receiver is communicated with a catalyst inlet of the oil agent contact area. The alkane dehydrogenation reaction can be carried out under negative pressure, the safety is good, and the alkane conversion rate and the olefin selectivity are high.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry, and in particular to a device and method for negative pressure driven catalytic dehydrogenation of alkanes to produce olefins. Background Art

[0002] Catalytic dehydrogenation of alkanes involves the removal of one molecule of hydrogen from an alkane to produce an olefin over a catalyst. The reaction is simple, with high yields of the target product, and has been widely adopted in industry worldwide. Based on the reactor type, alkane catalytic dehydrogenation technology can be categorized into three types: fixed-bed, moving-bed, and fluidized-bed. Lummus' Catofin process is the most widely used fixed-bed process. However, its development has been limited by the toxicity of its Cr-based catalyst, which poses environmental risks. Furthermore, the frequent switching of fixed-bed reactors during operation complicates operation and requires a large footprint. Moving-bed processes, exemplified by UOP's Oleflex process, utilize Pt-based catalysts, which have high production costs, demanding raw material requirements, and prone to deactivation during the reaction. With the increasing scale and expansion of alkane dehydrogenation equipment, the fluidized-bed process is gaining popularity. Its flexible operation, efficient and stable production process, and the use of environmentally friendly, non-precious metal, and highly efficient dehydrogenation catalysts have led to its increasing popularity among major manufacturers.

[0003] US20080161624A1 discloses a fluidized bed reactor with backmixing for the dehydrogenation of low-carbon alkanes. Alkanes react with a catalyst in a single fluidized bed reactor with backmixing. The deactivated catalyst is heated and then regenerated. The regenerated catalyst is returned to the fluidized bed reactor with backmixing for recycling, thereby maintaining the heat in the fluidized bed reactor with backmixing at a reasonable level. The reactor can improve the alkane conversion rate and olefin selectivity, and reduce the construction and operating costs of the device.

[0004] US20160272559A1 discloses a catalytic dehydrogenation method using an ascending fluidized bed reactor capable of processing feedstocks containing alkanes or alkylaromatics. The fluidized bed reactor comprises one or more reactors, with a reaction temperature of 500-800°C, a weight hourly space velocity of 0.1-1000, and a gas residence time of 0.1-10 seconds. A cyclone separator is used to separate the reacted oil mixture. A cooling device is provided between the reactor and the cyclone separator to terminate the thermal cracking reaction by cooling, thereby effectively improving the overall selectivity of the olefin product. WO2020 / 186937A1 discloses a circulating fluidized bed apparatus for alkane dehydrogenation, comprising a reaction unit and a regeneration unit. The reaction unit includes a reactor and a reaction settler, the reaction settler communicating with the reactor. A catalyst distributor is provided within the reactor, through which the catalyst is sprayed into the reactor along the reactor wall toward the central axis. The regeneration unit includes a regenerator containing the catalyst and a regenerator settler, the regenerator settler being located above the regenerator. The device can achieve higher alkane conversion rate and olefin yield.

[0005] The propane dehydrogenation reaction is a highly endothermic reaction with an increase in the number of molecules, and its heat of reaction is ΔH298θ = 124.3 kJ / mol. Increasing the reaction temperature and reducing the reaction pressure are beneficial to the propane dehydrogenation reaction. However, as the reaction temperature increases, the thermal cracking reaction intensifies, and the C-C bond cleavage of propane competes with the C-H bond cleavage, resulting in the production of byproducts such as methane, ethane, and ethylene. Therefore, the actual reaction temperature should not be too high. Reducing the reaction pressure can effectively increase the propane conversion rate while minimizing the impact on propylene selectivity. CN109554189A discloses a method for producing light olefins by cracking petroleum hydrocarbons under reduced pressure. A pressure reducing device connected to a cracking furnace is used to maintain a negative pressure in the pipelines through which the petroleum hydrocarbon feedstock flows in the convection section, radiant section, and waste heat boiler of the cracking furnace. The petroleum hydrocarbon feedstock is heated under reduced pressure, mixed with superheated steam, and then vaporized. The gaseous stream is further heated in the convection section to the crossover temperature before entering the radiant section furnace tubes, where the gaseous stream undergoes a cracking reaction at high temperature. This invention not only effectively solves the problem that special heavy cracking raw materials such as crude oil cannot be fully gasified in the convection section, but also can obtain a significantly higher yield of low-carbon olefins than the normal pressure cracking process.

[0006] A review of existing technologies reveals that enhancing the contact between the alkane feedstock and the catalyst and optimizing reaction conditions can effectively improve the conversion rate and olefin selectivity of alkane catalytic dehydrogenation reactions. However, further improvements in olefin selectivity are hampered by the presence of restricted reaction zones in the reactors used, the failure to terminate the reaction promptly afterward, and the reaction pressure. Therefore, improving alkane conversion and olefin selectivity in alkane catalytic dehydrogenation to olefins remains a pressing technical challenge. Summary of the Invention

[0007] To this end, the present invention provides a device and method for negative pressure driven catalytic dehydrogenation of alkanes to produce olefins, the purpose of which is to improve the alkane conversion rate and olefin selectivity.

[0008] In a first aspect, the present invention provides a negative pressure driven catalytic dehydrogenation device for alkane to olefin production, comprising a reaction unit and a regeneration unit;

[0009] The reaction unit includes a pre-lifting zone, an oil-agent contact zone, a reaction zone, a product quenching zone, a reaction outlet zone, an oil-agent separation zone and a stripping zone in sequence;

[0010] The device also includes a negative pressure driving device, a spent agent receiver and a regenerant agent receiver;

[0011] The oil and gas outlet of the oil-agent separation zone is connected to the oil and gas inlet of the negative pressure drive device, and the catalyst outlet of the oil-agent separation zone is connected to the catalyst inlet of the stripping zone;

[0012] The catalyst outlet of the stripping zone is communicated with the catalyst inlet of the spent catalyst receiver, and the catalyst outlet of the spent catalyst receiver is communicated with the spent catalyst inlet of the regeneration unit;

[0013] The regenerated catalyst outlet of the regeneration unit is communicated with the catalyst inlet of the regeneration agent receiver, and the catalyst outlet of the regeneration agent receiver is communicated with the catalyst inlet of the oil-agent contact zone.

[0014] In a second aspect, the present invention provides a method for negative pressure driven catalytic dehydrogenation of alkanes to produce olefins. The method is implemented based on the above-mentioned device. The alkane feedstock and the catalyst are contacted and mixed in the oil contact zone, and then enter the reaction zone for catalytic reaction.

[0015] Beneficial effects:

[0016] (1) The present invention provides a negative pressure drive device and adopts negative pressure operation to reduce the reaction pressure, promote the alkane dehydrogenation reaction to move in the positive direction, and improve the alkane conversion rate and olefin selectivity;

[0017] (2) The reaction unit and the regeneration unit are connected through the spent agent receiver and the regenerant agent receiver, ensuring the safety of negative pressure operation in the reaction unit;

[0018] (3) Using an efficient oil contact zone to strengthen the contact between alkanes and catalysts, promoting the initiation of catalytic dehydrogenation reactions; through a reasonable reactor type, providing a suitable reaction environment for the catalytic dehydrogenation reaction of alkanes, promoting the progress of the catalytic dehydrogenation reaction, and improving the alkane conversion rate;

[0019] (4) Through the product quenching zone, quick separation device and oil-agent separation zone, the oil-agent mixture after the reaction is quickly cooled and separated, so that the reaction is quickly terminated, the occurrence of side reactions is suppressed, and the olefin selectivity is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of a specific embodiment of the device for negative pressure driven catalytic dehydrogenation of alkanes to produce olefins according to the present invention;

[0021] Description of reference numerals:

[0022] 11- Pre-lifting zone 12- Oil contact zone 13- Reaction zone

[0023] 14-Product quenching zone 15-Reaction outlet zone 16-Stripping zone

[0024] 17-Oil agent separation area 18-Recycled agent receiver 19-Negative pressure drive device

[0025] 20-Regenerant receiver 21-Regeneration heating area 22-Regeneration area

[0026] 101-Pre-lift gas inlet 102-Alkane feed distributor 105-First catalyst delivery pipe

[0027] 106-Purge gas inlet 107-Quick separation device 108-First two-stage cyclone separator 109-Gas collecting chamber 110 Oil and gas pipeline 111-Stripping gas inlet

[0028] 112-Second catalyst delivery pipe 113-Purge mixed gas outlet 114-Reaction oil and gas outlet

[0029] 201-Fuel pipe 202-Fuel heating pipe 203-First regenerated catalyst delivery pipe

[0030] 204-reduction gas inlet 205-second two-stage cyclone separator 206-regeneration gas collection chamber

[0031] 207-regeneration flue gas outlet 208-second regeneration catalyst delivery pipe 209-reduction mixed gas outlet DETAILED DESCRIPTION

[0032] The present application will be further described in detail below through the accompanying drawings and examples, through which the features and advantages of the present application will become more clear and distinct.

[0033] The word "exemplary" is used exclusively herein to mean "serving as an example, example, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0034] In this specification, the terms "upstream" and "downstream" are based on the flow direction of the reactants. For example, when the reactants flow from bottom to top, "upstream" refers to a position below, while "downstream" refers to a position above.

[0035] In addition, the technical features involved in different embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0036] In a first aspect, the present invention provides a device for catalytically dehydrogenating alkanes to produce olefins driven by negative pressure, such as Figure 1 As shown, it includes a reaction unit and a regeneration unit;

[0037] The reaction unit includes a pre-elevation zone 11, an oil-agent contact zone 12, a reaction zone 13, a product quenching zone 14, a reaction outlet zone 15, an oil-agent separation zone 17 and a stripping zone 16 in sequence;

[0038] The device further comprises a negative pressure driving device 19, a spent agent receiver 18 and a regenerant agent receiver 20;

[0039] The oil and gas outlet of the oil-agent separation zone 17 is connected to the oil and gas inlet of the negative pressure drive device 19, and the catalyst outlet of the oil-agent separation zone 17 is connected to the catalyst inlet of the stripping zone 16;

[0040] The catalyst outlet of the stripping zone 16 is communicated with the catalyst inlet of the spent catalyst receiver 18, and the catalyst outlet of the spent catalyst receiver 18 is communicated with the spent catalyst inlet of the regeneration unit;

[0041] The regenerated catalyst outlet of the regeneration unit is communicated with the catalyst inlet of the regeneration agent receiver 20 , and the catalyst outlet of the regeneration agent receiver 20 is communicated with the catalyst inlet of the oil-agent contact zone 12 .

[0042] It should be noted that in the above-mentioned device of the present invention, from upstream to downstream, including the above-mentioned pre-lifting zone, oil-agent contact zone and other zones, any two adjacent zones are fluidically connected.

[0043] The device of the present invention is provided with a negative pressure drive device 19, which can extract oil and gas. The pressure in the reaction unit can be adjusted by adjusting the output power of the negative pressure drive device. By making the reaction zone negative pressure, the reaction of dehydrogenation of alkanes to produce olefins can be better carried out in the direction of reacting to produce olefins, thereby improving the alkane conversion rate and olefin selectivity.

[0044] The oil and gas separated in the oil-agent separation zone 17 first enter the negative pressure drive device 19 before being output. The spent catalyst obtained by stripping in the stripping zone 16 first enters the spent catalyst receiver 18 for oil and gas purge, and then enters the regeneration unit for regeneration. The regenerated catalyst obtained in the regeneration unit first enters the regeneration agent receiver 20 for reduction, and then enters the oil-agent contact zone 12 for recycling. By placing the spent catalyst receiver 18 and the regeneration agent receiver 20 between the reaction unit and the regeneration unit, the present device avoids direct connection between the negative pressure reaction unit and the constant pressure regeneration unit, enabling the reaction unit to operate under negative pressure while significantly improving safety.

[0045] In one embodiment of the above device of the present invention, the negative pressure driving device 19 is selected from a combination of one or more of a centrifugal negative pressure fan, an axial flow negative pressure fan, a diagonal flow negative pressure fan and a cross flow negative pressure fan;

[0046] The negative pressure driving device 19 is further provided with a reaction oil and gas outlet 114 .

[0047] It should be noted that the reaction oil and gas separated in the oil-agent separation zone passes through gas collection chamber 109 and is introduced into negative pressure drive device 19 via oil and gas pipeline 110. The oil and gas ultimately exit through reaction oil and gas outlet 114. Adjusting the output power of the negative pressure drive device adjusts the pressure in the reaction unit, allowing the reaction zone to operate under negative pressure, thereby improving alkane conversion and olefin selectivity. Using one or more of the aforementioned negative compressors in combination as negative pressure drive device 19 effectively controls the pressure in the reaction unit, allowing the reaction to proceed under negative pressure, resulting in more alkane dehydrogenation reactions to olefins, and improving alkane conversion and olefin selectivity.

[0048] In another embodiment of the above-mentioned apparatus of the present invention, the spent agent receiver 18 and the regenerant agent receiver 20 are lock hoppers.

[0049] It should be noted that the spent catalyst receiver 18 can transport the spent catalyst stripped from the negative pressure reaction unit to the regeneration unit at a constant pressure, while the regenerant receiver 20 can transport the regenerated catalyst from the regeneration unit at a constant pressure to the negative pressure reaction unit. Therefore, the spent catalyst receiver 18 and the regenerant receiver 20 can each be independently selected from lock hoppers of different models. Using lock hoppers as the spent catalyst receiver 18 and the regenerant receiver 20, respectively, can collaborate with the negative pressure drive device to effectively control the different pressures in the reaction unit and the regeneration unit, enhancing the safety of the entire device.

[0050] In one embodiment of the above device of the present invention, the pre-lifting zone 11 is provided with a pre-lifting gas inlet 101;

[0051] The oil agent contact zone 12 is provided with an alkane feed distributor 102 and a catalyst feed distributor, and the catalyst outlet of the regeneration agent receiver 20 is connected to the catalyst feed distributor;

[0052] The stripping zone 16 is provided with a stripping gas inlet 111 .

[0053] It should be noted that a pre-lift gas inlet can be provided at the bottom of the pre-lift zone, and pre-lift gas can be introduced into the pre-lift zone through the pre-lift gas inlet, so that the fully contacted alkane feedstock and catalyst mixture, along with the pre-lift gas, enter the reaction zone from the oil contact zone to carry out the catalytic dehydrogenation reaction of the alkane. The pre-lift gas can be selected from one or more of water vapor, nitrogen, and dry gas familiar to those skilled in the art, preferably water vapor. By providing an alkane feed distributor and a catalyst feed distributor, the alkane feedstock and the regenerated catalyst from the regeneration unit can be brought into more complete contact in the oil contact zone, thereby promoting the initiation of the catalytic dehydrogenation reaction.

[0054] The alkane feed distributor can be annular, the height of the alkane feed distributor from the bottom of the oil-agent contact zone can account for 0 to 1 / 4 of the height of the oil-agent contact zone, the diameter of the alkane feed hole is 1 / 4 to 3 / 4 of the width of the alkane feed distributor ring, the alkane feed hole is directed upward, the angle between the opening direction of the alkane feed hole and the central axis of the alkane feed distributor can be 30 to 50 degrees, and the opening ratio can be 70 to 90%. The catalyst feed distributor can be disc-shaped, the height of the catalyst distributor from the bottom of the oil-agent contact zone can account for 1 / 2 to 3 / 4 of the height of the oil-agent contact zone, the catalyst feed distributor is provided with multiple catalyst feed holes, the opening ratio of the catalyst feed distributor can be 70 to 90%, and the catalyst feed holes are directed downward.

[0055] The spent catalyst separated from the oil-agent separation zone enters the stripping zone for stripping. Stripping gas is introduced into the stripping zone through the stripping gas inlet to remove residual reaction oil vapor from the spent catalyst. The stripping gas can be selected from one or more of steam, nitrogen, and dry gas, with steam being preferred. The stripped spent catalyst is introduced into the spent catalyst receiver 18 via a first spent catalyst delivery pipe 105. The catalyst inlet of the spent catalyst receiver is connected to the catalyst outlet of the stripping zone. After being purged from the spent catalyst receiver 18 to remove oil vapor, the spent catalyst enters the regeneration unit through a second spent catalyst delivery pipe 112 for regeneration.

[0056] In one embodiment of the above-mentioned device of the present invention, a quick separation device 107 is provided between the product quenching zone 14 and the reaction outlet zone 15, and the oil separation zone 17 is provided with a first two-stage cyclone separator 108 and a gas collecting chamber 109;

[0057] The outlet of the product quenching zone 14 is connected to the inlet of the quick separation device 107, the catalyst outlet of the quick separation device 107 is connected to the catalyst inlet of the stripping zone 16, and the oil and gas outlet of the quick separation device 107 is connected to the inlet of the reaction outlet zone 15;

[0058] The outlet of the reaction outlet zone 15 is connected to the inlet of the first two-stage cyclone separator 108, the catalyst outlet of the first two-stage cyclone separator 108 is connected to the catalyst inlet of the stripping zone 16, the oil and gas outlet of the first two-stage cyclone separator 108 is connected to the oil and gas inlet of the gas collecting chamber 109, and the oil and gas outlet of the gas collecting chamber 109 is connected to the oil and gas inlet of the negative pressure drive device 19 via an oil and gas pipeline 110.

[0059] It should be noted that the reaction outlet zone can be located inside the oil-agent separation zone. The oil-agent mixture after the reaction is introduced into the product quenching zone for rapid cooling and then enters the quick separation device 107 for rapid separation of oil, gas and catalyst. The catalyst obtained by the rapid separation enters the stripping zone for stripping. The oil and gas carrying catalyst fine powder obtained by the rapid separation enters the first two-stage cyclone separator 108 through the reaction outlet zone 15 for further separation. The catalyst obtained by cyclone separation enters the stripping zone for stripping. The oil and gas obtained by cyclone separation enter the negative pressure drive device 19 after passing through the gas collecting chamber 109 and the oil and gas pipeline 110, and then the oil and gas are output.

[0060] In the present invention, Figure 1 In the device shown, the quick separation device can be a combination of one or more of a cyclone quick separator, a three-leaf quick separator, a catapult quick separator, a U-shaped tube separator and a wall-cutting quick separator, and the outlet of the quick separation device is connected to the reaction outlet zone.

[0061] The coordinated operation of the two separation devices allows for rapid separation of the post-reaction oil-agent mixture, further suppressing side reactions and improving olefin selectivity. Furthermore, the rapid separation device, after initial separation of the post-reaction oil-agent mixture, not only reduces the load on the first two-stage cyclone separators, improving separation efficiency, but also reduces the oil, gas, and catalyst gas velocities at the inlets of the first two-stage cyclone separators, minimizing catalyst wear and loss.

[0062] In one embodiment of the above device of the present invention, the spent catalyst receiver 18 is further provided with a purge gas inlet 106 and a purge mixed gas outlet 113;

[0063] The purge mixed gas outlet 113 is communicated with the upper portion of the oil-agent separation zone 17 .

[0064] It should be noted that a purge gas is introduced into the spent catalyst receiver to remove the reaction oil and gas on the spent catalyst, and then the spent catalyst enters the regeneration unit for regeneration.

[0065] In another embodiment of the above device of the present invention, the regeneration unit includes a regeneration and heating zone 21 and a regeneration zone 22;

[0066] The regeneration and heating zone 21 is located inside or outside the regeneration zone 22. The regeneration and heating zone 21 is provided with a fuel pipe 201 for introducing fuel. The heat outlet of the regeneration and heating zone 21 is connected to the regeneration zone 22 via a fuel heating pipe 202.

[0067] The catalyst inlet of the regeneration unit is connected to the regeneration zone 22, and the catalyst outlet of the regeneration zone 22 is connected to the inlet of the second two-stage cyclone separator 205;

[0068] The flue gas outlet of the second two-stage cyclone separator 205 is connected to the inlet of the regeneration plenum 206, and the regeneration plenum 206 is provided with a regeneration flue gas outlet 207; the catalyst outlet of the second two-stage cyclone separator 205 is connected to the regenerated catalyst outlet of the regeneration unit.

[0069] It should be noted that the fuel is introduced through the fuel pipe and burned, thereby replenishing heat for the regeneration zone, enabling the entire reaction unit and regeneration unit to reach thermal equilibrium. The regenerated catalyst is regenerated in an oxygen-containing atmosphere in the regeneration zone, burning off the coke deposited on the regenerated catalyst and converting the active components in the catalyst to an oxidized state. After regeneration, the catalyst is separated from the regeneration flue gas carried by the second two-stage cyclone separator. The regeneration flue gas passes through the gas collection chamber and is led out of the regeneration unit through the regeneration flue gas outlet. The regenerated catalyst flows out of the catalyst outlet of the second two-stage cyclone separator 205, passes through the regenerated catalyst outlet of the regeneration unit, and enters the regeneration agent receiver 20.

[0070] In one embodiment of the above device of the present invention, the regenerant receiver 20 is further provided with a reducing gas inlet 204 and a reducing mixed gas outlet 209;

[0071] The reducing mixed gas outlet 209 is communicated with the upper portion of the regeneration zone 22 .

[0072] It should be noted that the regenerated oxidized catalyst is first introduced into the regeneration agent receiver. Reducing gas is introduced through the reducing gas inlet to reduce the regenerated oxidized catalyst, and the reduced regenerated catalyst is recycled. The reducing mixed gas outlet 209 of the regeneration agent receiver 20 is connected to the upper portion of the regeneration zone 22. The regenerated catalyst outlet of the regeneration unit is connected to the catalyst inlet of the regeneration agent receiver 20 via the first regenerated catalyst delivery pipe 203. The catalyst outlet of the regeneration agent receiver 20 is connected to the catalyst feed distributor of the oil-agent contact zone via the second regenerated catalyst delivery pipe 208.

[0073] In the present invention, Figure 1 In the device shown, the reaction zone can be selected from a combination of one or more of a bubbling bed, a turbulent bed, a fast bed, and a transport bed. The reaction zone can be a constant diameter reaction zone, and the ratio of diameter to height can be 1:5 to 50, preferably 1:10 to 30.

[0074] In the present invention, Figure 1 In the device shown, the ratio of the diameter to the height of the product quenching zone can be 1:1 to 3, preferably 1:1 to 1.5. The product quenching zone can be provided with a heat exchange coil. The space enclosed by the heat exchange coil forms the product quenching zone. By introducing a quenching medium into the heat exchange coil, the reacted oil-agent mixture can be rapidly cooled to a lower temperature, thereby suppressing the occurrence of side reactions and improving olefin selectivity. The quenching medium can include one or more of quenching oil, quenching water, quenching gas, and an alkane feedstock.

[0075] In a second aspect, the present invention provides a method for negative pressure driven catalytic dehydrogenation of alkanes to produce olefins. The method is implemented based on the above-mentioned device. The alkane feedstock and the catalyst are contacted and mixed in the oil contact zone, and then enter the reaction zone for catalytic reaction.

[0076] It should be noted that the above method of the present invention may further include an alkane preheating step, wherein the alkane feedstock is first preheated to 350-500° C. and then meets and fully contacts the regenerated catalyst in the oil contact zone.

[0077] In one embodiment of the above method of the present invention, the purge gas introduced into the spent catalyst receiver 18 through the purge gas inlet 106 is an inert gas, which is selected from one or more of nitrogen, helium and argon.

[0078] It should be noted that, by selecting the above-mentioned inert gas as the purge gas, the oil and gas remaining in the spent catalyst after stripping can be removed well.

[0079] In another embodiment of the above method of the present invention, the reducing gas introduced into the regenerant receiver 20 through the reducing gas inlet 204 is selected from one or more of hydrogen, methane, refinery dry gas and oilfield dry gas.

[0080] It should be noted that, by selecting the above-mentioned reducing gas, the oxidized catalyst from the regeneration unit can be effectively reduced to an activated state, and then returned to the oil-agent contact zone for recycling.

[0081] In one embodiment of the above method of the present invention, the reaction conditions in the reaction zone 13 include:

[0082] The reaction temperature is 520-680°C, preferably 540-660°C; the reaction pressure is -80-0 kPa, preferably -60--20 kPa; the catalyst density is 150-400 kg / m 3 , preferably 200~350kg / m 3 .

[0083] It should be noted that the above pressures may be gauge pressures. By controlling the conditions in the reaction zone as above, the alkane conversion rate and olefin selectivity can be further improved.

[0084] In one embodiment of the above method of the present invention, the regeneration conditions of the regeneration unit include:

[0085] The regeneration temperature is 650-750℃, the regeneration pressure is 0-200kPa, and the catalyst density is 50-500kg / m 3 , the regeneration gas includes oxygen and / or air;

[0086] The reaction pressure is 50 to 250 kPa lower than the regeneration pressure, preferably 80 to 200 kPa lower;

[0087] The fuel introduced into the regeneration and heating zone (21) through the fuel pipe (201) includes one or more of methane, ethane, dry gas, liquefied gas and fuel oil, preferably the dry gas generated by the device;

[0088] The alkane raw material is selected from C2 to C8 alkanes.

[0089] It should be noted that the above pressures may be gauge pressures, and the regeneration gas may also be a mixed gas containing oxygen. By controlling the regeneration unit conditions as described above, the regenerated catalyst can exhibit excellent catalytic activity, particularly in the dehydrogenation of alkanes to olefins. In particular, by controlling the difference between the reaction pressure and the regeneration pressure as described above, the alkanes can be further enhanced to react toward the target olefins, thereby improving both the alkane conversion rate and the olefin selectivity.

[0090] It should be noted that the conditions of the oil contact zone 12 may include: a temperature of 500-700°C, preferably 520-680°C, a catalyst density of 100-500 kg / m 3 , preferably 150~400kg / m 3 The residence time of the alkane feedstock and the catalyst in the oil agent contact space is 0.05 to 0.5 s, preferably 0.1 to 0.3 s; the temperature of the product quenching zone 14 can be 200 to 550° C., preferably 250 to 500° C.

[0091] It should be noted that, in the above method of the present invention, the catalyst may include an active component and a carrier; the active component is preferably selected from one or more metals or oxides of Zn, Fe, Co, Ni, V, Sn and Mg, and the carrier is selected from one or more of Al2O3, SiO2, ZrO2, TiO2 and molecular sieves; based on the weight of the catalyst, the content of the active component is 10-90%, and the content of the carrier is 10-90%; preferably, the content of the active component is 20-70%, and the content of the carrier is 30-80%.

[0092] The present invention is further described in detail below by way of examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the experimental instruments and raw materials involved are all commercially available products.

[0093] The raw materials used in the examples and comparative examples are propane, n-butane and isobutane, and the catalyst used is an alkane dehydrogenation catalyst prepared by the Sinopec Research Institute of Petroleum Processing.

[0094] The chemical composition and properties of the alkane dehydrogenation catalyst are shown in Table 1.

[0095] Table 1 Composition and properties of alkane dehydrogenation catalysts

[0096]

[0097]

[0098] In the following examples and comparative examples, the alkane conversion and alkane selectivity were calculated as follows:

[0099] Alkane conversion rate = (mass fraction of alkanes in the feedstock - mass fraction of alkanes in the product) ÷ mass fraction of alkanes in the feedstock;

[0100] Olefin selectivity = (mass fraction of olefins in the product ÷ mass fraction of alkanes in the feed) ÷ alkane conversion.

[0101] In the following embodiments, the alkane feed distributor is annular, the height of the alkane feed distributor from the bottom of the oil contact zone accounts for 1 / 4 of the height of the oil contact zone, the diameter of the alkane feed hole is 1 / 2 of the width of the alkane feed distributor ring, the direction of the feed hole is upward, and the angle with the central axis of the alkane feed distributor is 45 degrees, and the porosity of the alkane feed distributor is 85%; the catalyst feed distributor is disc-shaped, the height of the catalyst feed distributor from the bottom of the oil contact zone accounts for 3 / 4 of the height of the oil contact zone, and a plurality of catalyst feed holes are provided on the catalyst distributor, the catalyst feed holes are directed downward, and the porosity of the catalyst feed distributor is 80%.

[0102] In the following embodiments, the reaction zone is a conveyor bed; the product quenching zone is cooled by a heat exchange coil, and the quenching medium in the heat exchange coil is specifically circulating water; and the quick separation device is a cyclone-type quick separator.

[0103] In the following examples, the temperature of the oil contact zone is 650°C and the catalyst density is 350 kg / m 3 The residence time of the alkane and the catalyst is 0.2s; the temperature of the product quenching zone is 420℃.

[0104] Examples 1-2

[0105] The test Figure 1 The test was conducted on the reaction-regeneration apparatus shown in FIG. The apparatus used in the test included a reaction unit and a regeneration unit. The reaction unit included, from upstream to downstream, a pre-elevation zone, an oil-agent contact zone, a reaction zone, a product quenching zone, a reaction outlet zone, an oil-agent separation zone, a stripping zone, and a negative pressure drive device. The regeneration unit included a regeneration and heating zone and a regeneration zone. The apparatus also included a spent agent receiver and a regenerant receiver.

[0106] The negative pressure driving device is specifically a centrifugal negative pressure fan, and the spent agent receiver and the regenerated agent receiver are locking hoppers.

[0107] The preheated alkane is introduced into the oil-agent contact zone through the alkane feed distributor, fully contacts with the catalyst introduced into the oil-agent contact zone through the catalyst feed distributor, and then is introduced into the reaction zone together with the pre-lifting gas from the pre-lifting zone for reaction. The oil-agent mixture after the reaction is introduced into the product quenching zone. After the temperature of the oil-agent mixture is reduced, it enters the quick separation device for quick separation. The catalyst obtained by the quick separation enters the stripping zone for stripping. The oil and gas carrying the catalyst fine powder obtained by the quick separation is introduced into the oil-agent separation zone through the reaction outlet zone. The reaction oil and gas separated by the first two-stage cyclone separator is introduced into the negative pressure drive device. The catalyst separated by the first two-stage cyclone separator is introduced into the stripping zone for stripping. The catalyst to be regenerated after stripping is introduced into the regenerated agent receiver, purged, and then introduced into the regeneration zone for regeneration. The regenerated catalyst is introduced into the regenerated agent receiver, reduced, and then introduced into the catalyst feed distributor for recycling.

[0108] The raw material used in this example was propane, the pre-lift gas was steam, the fuel used in the regeneration and heating zone was dry gas, the purge gas used in the spent catalyst receiver was nitrogen, the reducing gas used in the regenerated catalyst receiver was dry gas, and the regeneration gas was air. The reaction conditions and results are shown in Table 2.

[0109] Comparative Example 1

[0110] The method of Example 1 was followed, except that no negative pressure drive device was provided, and the reaction oil and gas were directly drawn out of the device. The reaction conditions and results are shown in Table 2.

[0111] Comparative Example 2

[0112] The method of Example 1 was followed, except that the negative pressure drive device, spent catalyst receiver, and regenerated catalyst receiver were omitted. The spent catalyst obtained from the stripping zone was directly introduced into the regeneration zone for regeneration. The regenerated catalyst from the regeneration zone was then directly introduced into the oil-agent contact zone for contact with the alkane feedstock. The reaction conditions and results are shown in Table 2.

[0113] Table 2 Reaction conditions and reaction results of Examples 1-2 and Comparative Examples 1-2

[0114]

[0115]

[0116] Example 3

[0117] The method of Example 1 was followed, except that n-butane was used as the raw material. The reaction conditions and product distribution were as shown in Table 3.

[0118] Example 4

[0119] The method of Example 2 was followed, except that the raw material used was isobutane. The reaction conditions and product distribution were shown in Table 3.

[0120] Comparative Example 3

[0121] The method of Comparative Example 1 was followed, except that the raw material used was n-butane. The reaction conditions and product distribution were as shown in Table 3.

[0122] Comparative Example 4

[0123] The method of Comparative Example 2 was followed, except that the raw material used was isobutane. The reaction conditions and product distribution were shown in Table 3.

[0124] Table 3 Reaction conditions and reaction results of Examples 3 to 4 and Comparative Examples 3 to 4

[0125]

[0126]

[0127] As can be seen from Table 2 and Table 3, by using the device and method provided by the present invention, different reactions are enhanced, and the conversion rate of reactants and the selectivity of target products are greatly improved.

[0128] In the description of this application, it should be noted that the terms "upper", "lower", "inside", "outside", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships in the working state of this application. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on this application.

[0129] In the description of this application, it should be noted that, unless otherwise specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0130] The present application has been described above in conjunction with preferred embodiments, but these embodiments are merely exemplary and serve only as an illustrative example. On this basis, various replacements and improvements can be made to the present application, all of which fall within the scope of protection of the present application.

Claims

1. A negative pressure driven catalytic alkane dehydrogenation device to produce olefins, comprising a reaction unit and a regeneration unit; The reaction unit sequentially comprises a pre-lifting zone (11), an oil-agent contact zone (12), a reaction zone (13), a product quenching zone (14), a reaction outlet zone (15), an oil-agent separation zone (17) and a stripping zone (16); in, The device further comprises a negative pressure driving device (19), a spent agent receiver (18) and a regenerant agent receiver (20); The oil and gas outlet of the oil-agent separation zone (17) is communicated with the oil and gas inlet of the negative pressure driving device (19), and the catalyst outlet of the oil-agent separation zone (17) is communicated with the catalyst inlet of the stripping zone (16); The catalyst outlet of the stripping zone (16) is communicated with the catalyst inlet of the spent catalyst receiver (18), and the catalyst outlet of the spent catalyst receiver (18) is communicated with the spent catalyst inlet of the regeneration unit; The regenerated catalyst outlet of the regeneration unit is communicated with the catalyst inlet of the regeneration agent receiver (20), and the catalyst outlet of the regeneration agent receiver (20) is communicated with the catalyst inlet of the oil agent contact zone (12).

2. The device according to claim 1, wherein: The negative pressure driving device (19) is selected from a combination of one or more of a centrifugal negative pressure fan, an axial flow negative pressure fan, a diagonal flow negative pressure fan and a cross flow negative pressure fan; The negative pressure driving device (19) is also provided with a reaction oil and gas outlet (114).

3. The device according to claim 1 or 2, wherein: The spent agent receiver (18) and the regenerated agent receiver (20) are lock hoppers.

4. The device according to claim 1, wherein: The pre-lifting zone (11) is provided with a pre-lifting gas inlet (101); The oil agent contact zone (12) is provided with an alkane feed distributor (102) and a catalyst feed distributor, and the catalyst outlet of the regeneration agent receiver (20) is connected to the catalyst feed distributor; The stripping zone (16) is provided with a stripping gas inlet (111).

5. The device according to claim 1, wherein: A quick separation device (107) is provided between the product quenching zone (14) and the reaction outlet zone (15), and the oil agent separation zone (17) is provided with a first two-stage cyclone separator (108) and a gas collecting chamber (109); The outlet of the product quenching zone (14) is connected to the inlet of the quick separation device (107), the catalyst outlet of the quick separation device (107) is connected to the catalyst inlet of the stripping zone (16), and the oil and gas outlet of the quick separation device (107) is connected to the inlet of the reaction outlet zone (15); The outlet of the reaction outlet zone (15) is connected to the inlet of the first two-stage cyclone separator (108), the catalyst outlet of the first two-stage cyclone separator (108) is connected to the catalyst inlet of the stripping zone (16), the oil and gas outlet of the first two-stage cyclone separator (108) is connected to the oil and gas inlet of the gas collecting chamber (109), and the oil and gas outlet of the gas collecting chamber (109) is connected to the oil and gas inlet of the negative pressure drive device (19) via an oil and gas pipeline (110).

6. The device according to claim 1 or 5, wherein: The spent catalyst receiver (18) is further provided with a purge gas inlet (106) and a purge mixed gas outlet (113); The purge mixed gas outlet (113) is communicated with the upper portion of the oil-agent separation zone (17).

7. The device according to claim 1, wherein: The regeneration unit includes a regeneration heating zone (21) and a regeneration zone (22); The regeneration and heating zone (21) is located inside or outside the regeneration zone (22), and the regeneration and heating zone (21) is provided with a fuel pipe (201) for introducing fuel, and the heat outlet of the regeneration and heating zone (21) is connected to the regeneration zone (22) via the fuel heating pipe (202); The catalyst inlet of the regeneration unit is connected to the regeneration zone (22), and the catalyst outlet of the regeneration zone (22) is connected to the inlet of the second two-stage cyclone separator (205); The flue gas outlet of the second two-stage cyclone separator (205) is connected to the inlet of the regeneration plenum (206), and the regeneration plenum (206) is provided with a regeneration flue gas outlet (207); the catalyst outlet of the second two-stage cyclone separator (205) is connected to the regeneration catalyst outlet of the regeneration unit.

8. The device according to claim 7, wherein: The regenerant receiver (20) is further provided with a reducing gas inlet (204) and a reducing mixed gas outlet (209); The reducing mixed gas outlet (209) is communicated with the upper portion of the regeneration zone (22).

9. A method for producing olefins by catalytic dehydrogenation of alkanes driven by negative pressure, wherein: The method is implemented based on the device described in any one of claims 1 to 8. The alkane feedstock and the catalyst are contacted and mixed in the oil agent contact zone, and then enter the reaction zone for catalytic reaction.

10. The method according to claim 9, wherein: The purge gas introduced into the spent catalyst receiver (18) through the purge gas inlet (106) is an inert gas, which is selected from one or more of nitrogen, helium and argon.

11. The method according to claim 9, wherein: The reducing gas introduced into the regenerant receiver (20) through the reducing gas inlet (204) is selected from one or more of hydrogen, methane, refinery dry gas and oilfield dry gas.

12. The method according to claim 9, wherein: The reaction conditions in the reaction zone (13) include: The reaction temperature is 520-680°C, preferably 540-660°C; the reaction pressure is -80-0 kPa, preferably -60--20 kPa; the catalyst density is 150-400 kg / m 3 , preferably 200~350kg / m 3 .

13. The method according to claim 12, wherein: The regeneration conditions of the regeneration unit include: The regeneration temperature is 650-750℃, the regeneration pressure is 0-200kPa, and the catalyst density is 50-500kg / m 3 , the regeneration gas includes oxygen and / or air; The reaction pressure is 50 to 250 kPa lower than the regeneration pressure, preferably 80 to 200 kPa lower; The fuel introduced into the regeneration and heating zone (21) through the fuel pipe (201) includes one or more of methane, ethane, dry gas, liquefied gas and fuel oil, preferably the dry gas generated by the device; The alkane raw material is selected from C2 to C8 alkanes.

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