CN115779977B - System and method for continuously producing low-valence chromium-supported catalyst - Google Patents
System and method for continuously producing low-valence chromium-supported catalyst Download PDFInfo
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- CN115779977B CN115779977B CN202211377554.4A CN202211377554A CN115779977B CN 115779977 B CN115779977 B CN 115779977B CN 202211377554 A CN202211377554 A CN 202211377554A CN 115779977 B CN115779977 B CN 115779977B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 57
- 238000000034 method Methods 0.000 title claims abstract description 31
- 238000006243 chemical reaction Methods 0.000 claims abstract description 77
- 239000000463 material Substances 0.000 claims abstract description 32
- 238000001035 drying Methods 0.000 claims abstract description 30
- 238000006479 redox reaction Methods 0.000 claims abstract description 10
- 238000005470 impregnation Methods 0.000 claims abstract description 6
- 238000005507 spraying Methods 0.000 claims abstract description 4
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 claims description 42
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 38
- 239000011651 chromium Substances 0.000 claims description 37
- 229910052804 chromium Inorganic materials 0.000 claims description 29
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 24
- 235000006408 oxalic acid Nutrition 0.000 claims description 14
- 239000007864 aqueous solution Substances 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 12
- 239000000377 silicon dioxide Substances 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 9
- 238000010008 shearing Methods 0.000 claims description 8
- WGLPBDUCMAPZCE-UHFFFAOYSA-N chromium trioxide Inorganic materials O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 7
- 238000009826 distribution Methods 0.000 claims description 7
- 239000007921 spray Substances 0.000 claims description 7
- 239000012752 auxiliary agent Substances 0.000 claims description 6
- 229940117975 chromium trioxide Drugs 0.000 claims description 6
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 claims description 6
- 239000000243 solution Substances 0.000 claims description 6
- 238000007599 discharging Methods 0.000 claims description 5
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- 238000005299 abrasion Methods 0.000 claims description 4
- 239000012018 catalyst precursor Substances 0.000 claims description 4
- 238000003860 storage Methods 0.000 claims description 4
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 claims description 3
- APUPEJJSWDHEBO-UHFFFAOYSA-P ammonium molybdate Chemical compound [NH4+].[NH4+].[O-][Mo]([O-])(=O)=O APUPEJJSWDHEBO-UHFFFAOYSA-P 0.000 claims description 3
- 235000018660 ammonium molybdate Nutrition 0.000 claims description 3
- 239000011609 ammonium molybdate Substances 0.000 claims description 3
- 229940010552 ammonium molybdate Drugs 0.000 claims description 3
- 238000005520 cutting process Methods 0.000 claims description 3
- 229910000856 hastalloy Inorganic materials 0.000 claims description 3
- JHWIEAWILPSRMU-UHFFFAOYSA-N 2-methyl-3-pyrimidin-4-ylpropanoic acid Chemical compound OC(=O)C(C)CC1=CC=NC=N1 JHWIEAWILPSRMU-UHFFFAOYSA-N 0.000 claims description 2
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims description 2
- 239000005751 Copper oxide Substances 0.000 claims description 2
- 229910021380 Manganese Chloride Inorganic materials 0.000 claims description 2
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 230000009471 action Effects 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- WYYQVWLEPYFFLP-UHFFFAOYSA-K chromium(3+);triacetate Chemical compound [Cr+3].CC([O-])=O.CC([O-])=O.CC([O-])=O WYYQVWLEPYFFLP-UHFFFAOYSA-K 0.000 claims description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 claims description 2
- 229910001981 cobalt nitrate Inorganic materials 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims description 2
- 229910000431 copper oxide Inorganic materials 0.000 claims description 2
- CMMUKUYEPRGBFB-UHFFFAOYSA-L dichromic acid Chemical compound O[Cr](=O)(=O)O[Cr](O)(=O)=O CMMUKUYEPRGBFB-UHFFFAOYSA-L 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 235000002867 manganese chloride Nutrition 0.000 claims description 2
- 239000011565 manganese chloride Substances 0.000 claims description 2
- 229940099607 manganese chloride Drugs 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 2
- 229910052755 nonmetal Inorganic materials 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 claims description 2
- 229960004838 phosphoric acid Drugs 0.000 claims description 2
- 235000011007 phosphoric acid Nutrition 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims description 2
- 235000012239 silicon dioxide Nutrition 0.000 claims description 2
- 239000010936 titanium Substances 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 11
- 238000002360 preparation method Methods 0.000 description 15
- 229910052681 coesite Inorganic materials 0.000 description 10
- 229910052906 cristobalite Inorganic materials 0.000 description 10
- 229910052682 stishovite Inorganic materials 0.000 description 10
- 229910052905 tridymite Inorganic materials 0.000 description 10
- 230000001276 controlling effect Effects 0.000 description 7
- QDOXWKRWXJOMAK-UHFFFAOYSA-N chromium(III) oxide Inorganic materials O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 6
- 238000012986 modification Methods 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 229910052593 corundum Inorganic materials 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 3
- 229910001845 yogo sapphire Inorganic materials 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000012295 chemical reaction liquid Substances 0.000 description 2
- UBFMILMLANTYEU-UHFFFAOYSA-H chromium(3+);oxalate Chemical compound [Cr+3].[Cr+3].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O UBFMILMLANTYEU-UHFFFAOYSA-H 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000001694 spray drying Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229910001430 chromium ion Inorganic materials 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- HBXWYZMULLEJSG-UHFFFAOYSA-N chromium vanadium Chemical compound [V][Cr][V][Cr] HBXWYZMULLEJSG-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Catalysts (AREA)
Abstract
The invention provides a reaction system and a method for continuously producing a low-valence chromium-supported catalyst. The system comprises: a first-stage tubular reactor in which a redox reaction occurs; a secondary section tubular reactor in which an impregnation reaction occurs; an atomizer for spraying a reaction material; a drying tower for receiving the reaction material from the atomizer and drying; and a roasting furnace which receives the reaction material from the drying tower and performs roasting to obtain a product. The reaction system realizes the continuity of the whole process, greatly improves the productivity compared with the traditional intermittent process, has simple and flexible equipment, and can meet the requirement of the later process adjustment.
Description
Technical Field
The invention relates to the field of catalyst preparation, in particular to a system and a method for continuously producing a low-valence chromium-supported catalyst.
Background
Chromium element valence states are widely distributed between 0 and +6 valence states, and chromium oxide has various crystal forms structures including face-centered cubic, body-centered cubic, and the like; meanwhile, the low-valence chromium element can be compounded with other metals to form a multi-metal structure system, and a specific structure and performance are obtained through modification of an auxiliary agent, so that the low-valence chromium element catalyst is widely applied to ammoxidation, nitrile, polymerization and other reactions. To obtain better structural stability, the chromium element in low valence state is usually applied to the reaction after being carried by a carrier.
At present, documents or patents related to low-valence chromium supported catalysts mainly relate to development, improvement and optimization of the catalysts, and few researches on corresponding equipment and processes are reported. In addition, since the application scenes of the low-valence chromium-supported catalyst are mostly fixed bed reactors, fluidized bed reactors and the like, the problems of catalyst abrasion, loss and the like exist, and the fresh catalyst needs to be replenished periodically. The preparation process of the low-valence chromium-supported catalyst in the prior art is an intermittent process, and has the advantages of numerous equipment, complex operation, large labor investment and low productivity. Patent CN109384865B discloses a composite reduced chromium-vanadium catalyst and a preparation method thereof, which are used for ethylene polymerization reaction. Although the preparation method has better catalytic effect, the preparation method is limited to a small test stage, has a plurality of operation steps and has extremely low catalyst productivity. Patent CN112495422B discloses a method for preparing a silicon-based chromium catalyst by in-situ roasting, although the preparation process is optimized, the productivity of the catalyst can be greatly improved, the method has strong limitation, and the subsequent modification and optimization difficulty for the catalyst is high. Patent publication CN113797933a discloses a method for preparing chromium catalyst by using chromium oxalate, which reduces the discharge of high-valence chromium ions, but the chromium oxalate has poor thermal stability and harsh storage conditions.
At present, the preparation of the low-valence chromium-supported catalyst has two general problems, namely complex preparation process, batch operation, large investment and low productivity; secondly, the preparation process has strong pertinence, and the process system is difficult to meet the requirements of optimizing and modifying the later catalyst.
Disclosure of Invention
In order to solve the technical problems, the invention provides a system and a method for continuously producing a low-valence chromium-supported catalyst. In the method, oxalic acid is used as a reducing agent to reduce high-valence chromium to obtain low-valence chromium, then a carrier is used for impregnating and adsorbing the low-valence chromium, and finally the low-valence chromium supported catalyst is obtained after high-temperature roasting. The system solves the difficult problem of heat transfer of reaction, and saves more than 90% of the use amount of public works; the carbon dioxide released by the reaction is uniformly distributed in the system by utilizing a sieve plate, a redistributor and an atomizer, so that the particle size (D20:50+/-2 mu m; D50:60+/-2 mu m; D90:70+/-2 mu m) of the catalyst can be effectively regulated, the yield of the qualified catalyst product is increased to more than 75%, and the abrasion rate is lower than 4%. The system realizes the continuity of the whole process, greatly improves the productivity compared with the traditional intermittent process, has simple and flexible equipment, and can meet the requirement of the later process adjustment.
According to a first aspect of the present invention, there is provided a reaction system for continuously producing a chromium-supported catalyst in a low valence state, comprising:
a first-stage tubular reactor in which a redox reaction occurs, the first-stage tubular reactor comprising, in order, along the direction of flow of the material: the device comprises a first feed inlet, a second feed inlet, a multi-layer sieve plate, a third feed inlet and a first discharge outlet for discharging reaction materials;
a secondary section tubular reactor wherein an impregnation reaction occurs, comprising: the gas-liquid redistributor is arranged in the reactor, the multitube Cheng Guanshi reactor is provided with a plurality of reaction tubes which are parallel to the length direction of the secondary section tube reactor and are provided with openings at the ends, one end of the gas-liquid redistributor arranged at the inlet of the secondary section tube reactor is communicated with the first discharge port of the first section tube reactor and is used for feeding the reaction materials from the first section tube reactor; distribution holes in the gas-liquid redistributor are in one-to-one correspondence with a plurality of reaction tubes of the multitube Cheng Guanshi reactor;
The atomizer is communicated with the discharge port of the multitube Cheng Guanshi reactor and is used for spraying reaction materials;
The atomizer is arranged in the upper space of the drying tower, and the drying tower is used for receiving and drying the reaction materials from the atomizer;
And a roasting furnace which receives the reaction material from the drying tower and performs roasting to obtain a product.
Preferably, the first-stage tubular reactor is a serpentine tubular reactor.
Preferably, the first feed port is arranged at the end part of the first-stage tubular reactor, the second feed port is arranged at the side surface of the first-stage tubular reactor, and the feed mixer is arranged on the second feed port.
Preferably, the feed mixer is a baffle plate arranged inside the first-stage tubular reactor and positioned at the front end of the second feed inlet, which changes the flow direction of the material from the second feed inlet to flow along the first-stage tubular reactor.
Preferably, a plurality of baffles which are staggered with each other are arranged in the first-stage tubular reactor, and the baffles are positioned between the second feed inlet and the sieve plate; more preferably, the baffle cutting rate is 30% -40%.
Preferably, the sieve plate holes are diameter-reducing holes, the diameter-reducing angle alpha is 10-20 degrees, and the aperture beta of the feeding end is 5-10 mm.
Preferably, the spacing between the screen plates is 1.5-2 m.
Preferably, a high-pressure feed pump and a feed pipeline are respectively arranged between the first feed port and the second feed port and the storage tank of raw materials.
Preferably, a heat-insulating jacket is arranged outside the secondary section tubular reactor.
Preferably, the connecting pipeline, the first-section tubular reactor and the second-section tubular reactor are made of nonmetal, titanium or hastelloy.
Preferably, the atomizer is provided with a plurality of shearing discs and atomizing spray pipes, and discharge holes with diameters of 100-150 mu m are uniformly distributed on the spray pipes.
Preferably, an exhaust port is provided at the top of the drying tower for exhausting the gas generated during the drying process.
According to a second aspect of the present invention, there is provided a method for continuously producing a low-valence chromium-supported catalyst using the reaction system for continuously producing a low-valence chromium-supported catalyst according to the present invention, comprising the steps of:
1) Oxalic acid is fed through a first feed inlet, high-valence chromium is fed through a second feed inlet, and the oxalic acid and the high-valence chromium are mixed under the turbulent flow action of a sieve plate through an optional baffle plate and undergo oxidation-reduction reaction in the first-stage tubular reactor;
2) Feeding the carrier and optional auxiliary agent through a third feed inlet, mixing with the reaction material undergoing oxidation-reduction reaction, flowing into the reaction tube of the multitube Cheng Guanshi reactor through the gas-liquid redistributor for impregnation reaction,
3) The reaction material from the step 2) is atomized by an atomizer and then subjected to flash evaporation and drying in a drying tower to obtain a catalyst precursor;
4) And feeding the catalyst precursor into a roasting furnace, and roasting in an air atmosphere to obtain the low-valence chromium-supported catalyst.
Preferably, in the step 1), the feeding mole ratio of chromium element to oxalic acid in the high valence chromium raw material is 1: (2.8-3.2), preferably 1: (2.9-3.1).
Preferably, the high-valence chromium raw material is a compound having a chromium valence of +4 or more, and further preferably selected from chromium trioxide, dichromic acid, sodium dichromate, chromium acetate, and the like.
Preferably, the oxalic acid is fed in the form of a solution, preferably in the form of an aqueous solution, and even more preferably the oxalic acid solution has a mass concentration of 30% to 55%.
Preferably, the high valence chromium feedstock is fed in solution, preferably in aqueous solution, and more preferably the high valence chromium feedstock has a mass concentration of 40% to 60%.
Preferably, in step 1), an adiabatic reaction is carried out in the first-stage tubular reactor, wherein a temperature gradient exists, the inlet temperature of the reactor is 25-40 ℃, and the outlet temperature of the reactor is 155-170 ℃; the reaction pressure is 10 to 12barA; the reaction residence time is 1-5 min; the flow rate in the reactor is 0.2-1.5 m/s.
Preferably, the carrier is one or more selected from silicon dioxide, aluminum oxide, nickel oxide and copper oxide, and the auxiliary agent is one or more selected from aqueous solutions of cobalt nitrate, manganese chloride, ammonium molybdate, phosphoric acid and the like. Preferably, the auxiliary agent is used in an amount of less than 20wt% of the amount of the high valence chromium raw material.
Preferably, in the step 2), the feeding mole ratio of the carrier to the chromium element in the high-valence chromium raw material is (1.5-3.2) to 1.
Preferably, in the step 2), the reaction temperature of the secondary section tubular reactor is 155-170 ℃, the reaction pressure is 10-12 barA, the reaction residence time is 20-40 min, and the flow rate in the reactor is 0.25-0.5 m/min; a steam jacket is arranged outside the secondary section tube reactor and is used for system heat preservation.
Preferably, the rotation speed of the shearing disc in the atomizer is 12000-15000 r/min.
Preferably, the pressure in the drying tower is 50-90 kPaA, and the temperature is 90-150 ℃.
Further, in the step 4), the roasting furnace is continuously operated, the temperature is 400-500 ℃, the residence time is 4-6 h, the air atmosphere is in an air atmosphere, and the pressure is-15 kPaG to-5 kPaG.
Preferably, the particle size distribution D50 of the low-valence chromium-supported catalyst prepared according to the method of the present invention is 50-70 μm, the attrition rate is less than 4%, and the yield is more than 70%.
Drawings
FIG. 1 is a schematic diagram of a system for continuously producing a low valence chromium supported catalyst according to one embodiment of the present invention;
FIG. 2 is a schematic illustration of a dual stage tubular reactor (including a first stage tubular reactor and a second stage tubular reactor) according to one embodiment of the invention;
Fig. 3 is a schematic diagram of an atomizer according to one embodiment of the invention.
Reference numerals
Wherein: 1-first feed inlet, 2-second feed inlet, 3-two-stage reactor, 4-atomizer, 5-gas vent, 6-drying tower, 7-roasting furnace, 8-feed mixer, 9-baffle, 10-sieve plate, 11-first stage tubular reactor, 12-third feed inlet, 13-gas-liquid redistributor, 14-second stage tubular reactor, 15-shearing disc, 16-atomizing spray pipe.
Detailed Description
The invention will now be further illustrated by means of specific examples which are given solely by way of illustration of the invention and do not limit the scope thereof.
Example 1
Figures 1 to 3 show a system for continuous production of a low valence chromium supported catalyst comprising:
A first-stage tubular reactor 11, which is a serpentine tubular reactor in which a redox reaction occurs, comprising, in order, along the direction of flow of the material: the device comprises a first feed inlet 1 arranged at the end part of a first-stage tubular reactor, a second feed inlet 2 arranged at the side surface of the first-stage tubular reactor, 4 baffle plates 9, 120 layers of sieve plates 10, a third feed inlet 12 and a first discharge outlet for discharging reaction materials, wherein the baffle plates 9, 120 layers of sieve plates 10 are staggered with each other; wherein a baffle plate is arranged in the first-stage tubular reaction 11 and at the front end of the second feed inlet 2, so that the flow direction of the material from the second feed inlet 2 is changed to flow along the first-stage tubular reactor; the cutting rate of each baffle plate 9 is 30%, the distance between each baffle plate 9 is 0.3m, the holes in the sieve plates 10 are diameter-reduced holes, the diameter-reduced angle alpha is 15 degrees, the aperture beta of the feeding end is 5mm, and the interval between the sieve plates 10 is 1.5m;
A secondary section tubular reactor 14 in which an impregnation reaction occurs, comprising: a multi-pipe Cheng Guanshi reactor (length is 6 m) of 120 reaction pipes which are arranged in the gas-liquid redistributor 13, parallel to the length direction of the secondary pipe reactor 14 and open at the end, and one end of the gas-liquid redistributor 13 arranged at the inlet of the secondary pipe reactor 14 is communicated with a first discharge port of the primary pipe reactor 11 and is used for feeding reaction materials from the primary pipe reactor 11; outlets of distribution holes in the gas-liquid redistributor 13 are in one-to-one correspondence with a plurality of reaction tubes of the multitube Cheng Guanshi reactor; a heat-insulating jacket is provided outside the secondary section tubular reactor 14, and an inlet for introducing steam and an outlet for discharging condensate are provided on the jacket;
An atomizer 4, wherein the atomizer 4 is communicated with the discharge port of the multitube Cheng Guanshi reactor of the secondary section tubular reactor 14 and is used for spraying reaction materials; wherein, two shearing discs 15 positioned at different positions and a spray pipe 16 are arranged in the atomizer, and discharge holes with the diameter of 100 mu m are uniformly distributed on the spray pipe 16;
A drying tower 6, half length of the sub-section pipe reactor 14 and the atomizer 4 are disposed in an upper space of the drying tower 6, for receiving the reaction material from the atomizer 4 and drying; a pressure gauge and an exhaust port 5 for exhausting gas generated during the drying process are arranged at the top of the drying tower 6;
a roasting furnace 7 which receives the reaction material from the drying tower and performs roasting to obtain a product.
The first feed inlet 1 and the second feed inlet 2 are respectively connected with a storage tank through a hastelloy pipeline and a high-pressure pump.
Preparation of Cr 2O3/SiO2 catalyst
The 50wt% oxalic acid aqueous solution and the 50wt% chromium trioxide aqueous solution with the feed temperature of 25 ℃ are respectively introduced into the first-stage tubular reactor 11 of the double-stage tubular reactor 3 through the first feed inlet 1 and the second feed inlet 2 by a high-pressure feed pump at the feed temperature of 1000kg/h and 370.3kg/h, the adiabatic reaction is carried out in the first-stage tubular reactor 11, the outlet temperature is 155 ℃, the reaction pressure is controlled to be 10barA, the reaction residence time is 2min, and the material flow rate is 1.5m/s. Wherein the redox reaction equation is ：2CrO3+6H2C2O4＝Cr2(C2O4)3+6CO2+6H2O.
30Wt% of silica sol carrier enters the first-stage tubular reactor 11 through a third feed inlet 12 in the middle of the reactor at a feed rate of 1111.2kg/h, is mixed with the reaction material undergoing the oxidation-reduction reaction, enters the second-stage tubular reactor 14 after being distributed by a redistributor 13, and controls the temperature of the second-stage tubular reactor 14 to be 155 ℃, the pressure to be 10barA, the reaction residence time to be 25min, and the flow rate in the reactor to be 0.3m/min; the reaction liquid obtained in the secondary section tubular reactor 14 enters an atomizer 4, the rotating speeds of two shearing discs 15 in the atomizer 4 are 12000r/min, the pressure in a drying tower 6 is controlled to be 50kPaA, and the temperature is 150 ℃; and (3) feeding the powder subjected to spray drying into a roasting furnace 7, controlling the temperature of the roasting furnace 7 to be 400 ℃, controlling the air atmosphere to be-10 kPaG, and controlling the residence time to be 4 hours to obtain the final Cr 2O3/SiO2 catalyst.
Example 2
Preparation of Cr 2O3/Al2O3 catalyst
A Cr 2O3/Al2O3 catalyst was prepared in substantially the same manner as in example 1, except that 30wt% of the alumina sol carrier was fed into the first-stage tubular reactor 11 through the third feed port 12 of the reactor at a feed rate of 950kg/h, and fed into the second-stage tubular reactor 14 together with the reaction liquid obtained in the first-stage reactor 11 after passing through the redistributor distribution 13, while adjusting the rotation speed of the shearing disc 15 in the atomizer 4 to 14000r/min, to finally obtain the Cr 2O3/Al2O3 catalyst.
Example 3
Preparation of CrO 3-Cr2O3/SiO2 catalyst
CrO 3-Cr2O3/SiO2 catalyst was prepared in essentially the same manner as in example 1, except that the 50wt% chromium trioxide aqueous solution was fed at a rate of 396.7kg/h while controlling the oven temperature to 500℃and air atmosphere at a pressure of-10 kPaG for a residence time of 4 hours, to finally obtain CrO 3-Cr2O3/SiO2 catalyst.
Example 4
Preparation of MoO 3-Cr2O3/SiO2 catalyst
A MoO 3-Cr2O3/SiO2 catalyst was prepared in substantially the same manner as in example 1, except that a 50wt% ammonium molybdate aqueous solution was fed at a feed rate of 54kg/h and a 30wt% silica sol carrier was fed at a feed rate of 1111.2kg/h from the third feed port 12 into the sub-section tube reactor, the temperature of the sub-section tube reactor was controlled at 165℃and the pressure at 12barA for a reaction residence time of 40 minutes, to finally obtain a MoO 3-Cr2O3/SiO2 catalyst.
Comparative example 1
Preparation of batch Cr 2O3/SiO2 catalyst
100Kg of 50wt% oxalic acid aqueous solution is added into a reaction kettle, 50wt% chromium trioxide aqueous solution is added into the reaction kettle through a high-pressure feed pump at a dropping speed of 37kg/h, heat transfer is started, the temperature of the reaction kettle is maintained at 70 ℃, and the pressure of the reaction kettle is maintained at normal pressure. Stirring is maintained, chromium trioxide is stopped to be fed after the mixture is dropwise added for 6 hours, 650kg of 30wt% silica sol carrier is introduced, and the reaction is continued for 4 hours at the normal pressure at the temperature of 70 ℃.
After the reaction is finished, the temperature of the reaction kettle is increased to 150 ℃, the material is discharged to an atomizer by utilizing a high-pressure conveying pump, the rotating speed of the atomizer is set to 12000r/min, and the pressure in the drying tower is controlled to be 50kPaA; and (3) feeding the powder subjected to spray drying into a high-temperature roasting furnace, controlling the temperature of the roasting furnace to be 400 ℃, controlling the air atmosphere to be under the pressure of-10 kPaG, and controlling the residence time to be 4 hours to obtain the final Cr 2O3/SiO2 catalyst.
Table 1: the catalyst test results obtained in examples 1 to 4 and comparative example 1.
The particle size distribution of the catalyst is tested by using a BT-2900 dry-wet method image particle size analyzer, particles moving at high speed are shot by a special camera, and an analysis result is output after the image is processed and analyzed by specially designed particle analysis software. The attrition index of the catalyst was tested using an HT9801 FCC catalyst attrition index tester, and after 5 hours of blowing and grinding a catalyst sample with a constant flow of nitrogen, the attrition index was calculated as the proportion of the sample having a particle size of less than 15 μm.
By adopting the process system for continuously producing the low-valence chromium-supported catalyst, the obtained catalyst has obvious advantages in particle size distribution and abrasion index compared with the traditional batch preparation process. Meanwhile, the catalyst achieves a yield of more than 75%. The process system based on the invention has strong flexibility for the catalyst modification requirements of different scenes and can also be realized.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the method of the present invention, which modifications and additions are also to be considered as within the scope of the present invention.
Claims (12)
1. A reaction system for continuously producing a low valence chromium supported catalyst, comprising:
A first-stage tubular reactor in which a redox reaction occurs, the first-stage tubular reactor comprising, in order, along the direction of flow of the material: the device comprises a first feed inlet, a second feed inlet, a multi-layer sieve plate, a third feed inlet and a first discharge outlet for discharging reaction materials, wherein the holes of the sieve plate are diameter-reduced holes, the diameter-reduced angle alpha is 10-20 degrees, the aperture beta of a feed end is 5-10 mm, and the interval between the sieve plates is 1.5-2 m;
A secondary section tubular reactor wherein an impregnation reaction occurs, comprising: the gas-liquid redistributor is arranged in the reactor, the multitube Cheng Guanshi reactor is provided with a plurality of reaction tubes which are parallel to the length direction of the secondary section tube reactor and are provided with openings at the ends, one end of the gas-liquid redistributor arranged at the inlet of the secondary section tube reactor is communicated with the first discharge port of the first section tube reactor and is used for feeding the reaction materials from the first section tube reactor; distribution holes in the gas-liquid redistributor are in one-to-one correspondence with a plurality of reaction tubes of the multitube Cheng Guanshi reactor;
The atomizer is communicated with the discharge port of the multitube Cheng Guanshi reactor and is used for spraying reaction materials;
The atomizer is arranged in the upper space of the drying tower, and the drying tower is used for receiving the reaction materials from the atomizer and drying the reaction materials;
And a roasting furnace which receives the reaction material from the drying tower and carries out roasting to obtain a product.
2. The reaction system according to claim 1, wherein,
The first-stage tubular reactor is a serpentine tubular reactor; and/or
The first feed port is arranged at the end part of the first-stage tubular reactor, the second feed port is arranged at the side surface of the first-stage tubular reactor, and the second feed port is provided with a feed mixer; and/or
The feed mixer is a baffle plate which is arranged in the first section tubular reactor and positioned at the front end of the second feed inlet, and the flow direction of the material from the second feed inlet is changed into the flow along the first section tubular reactor.
3. The reaction system according to claim 1, wherein,
A plurality of baffles which are staggered with each other are arranged in the first section tubular reactor, and the baffles are positioned between the second feed inlet and the sieve plate; and/or the number of the groups of groups,
The cutting rate of the baffle plate is 30% -40%.
4. The reaction system according to claim 1, wherein,
A high-pressure feed pump and a feed pipeline are respectively arranged between the first feed inlet and the second feed inlet and between the first feed inlet and the raw material storage tank; and/or
A heat-insulating jacket is arranged outside the secondary section tubular reactor; and/or
The connecting pipeline, the first section tubular reactor and the second section tubular reactor are made of nonmetal, titanium or hastelloy.
5. The reaction system according to claim 1 to 4, wherein,
The atomizer is provided with a plurality of shearing discs and an atomizing spray pipe, and discharge holes with the diameter of 100-150 mu m are uniformly distributed on the spray pipe; and/or
An outlet is arranged at the top of the drying tower and is used for discharging the gas generated in the drying process.
6. A method for continuously producing a low-valence chromium-supported catalyst using the reaction system according to any one of claims 1 to 5, and comprising the steps of:
1) Oxalic acid is fed through a first feed inlet, high-valence chromium is fed through a second feed inlet, and mixed under the turbulent flow action of the sieve plates through optional baffles, and oxidation-reduction reaction occurs in the first-stage tubular reactor, wherein adiabatic reaction is performed in the first-stage tubular reactor, a temperature gradient exists, the inlet temperature of the reactor is 25-40 ℃, and the outlet temperature of the reactor is 155-170 ℃; the reaction pressure is 10 to 12barA; the reaction residence time is 1-5 min; the flow rate in the reactor is 0.2-1.5 m/s;
2) Feeding the carrier and optional auxiliary agent through a third feed inlet, mixing with the reaction material undergoing oxidation-reduction reaction, flowing into the reaction tube of the multitube Cheng Guanshi reactor through the gas-liquid redistributor for impregnation reaction,
3) After the reaction material from the step 2) is atomized by the atomizer, flash evaporation and drying are carried out in a drying tower to obtain a catalyst precursor;
4) And feeding the catalyst precursor into a roasting furnace, and roasting in an air atmosphere to obtain the low-valence chromium-supported catalyst.
7. The method of claim 6, wherein,
In the step 1), the feeding mole ratio of chromium element in the high valence chromium raw material to oxalic acid is 1:2.8-3.2; and/or
The high-valence chromium raw material is a compound with a chromium valence of more than +4; and/or
The oxalic acid is fed in the form of a solution; and/or
The high valence chromium feedstock is fed as a solution.
8. The method of claim 7, wherein,
In the step 1), the feeding mole ratio of chromium element in the high valence chromium raw material to oxalic acid is 1:2.9-3.1; and/or
The high-valence chromium raw material is one or more selected from chromium trioxide, dichromic acid, sodium dichromate and chromium acetate; and/or
The oxalic acid is fed in the form of an aqueous solution; and/or
The high valence chromium feedstock is fed as an aqueous solution.
9. The method of claim 8, wherein,
The mass concentration of the oxalic acid solution is 30% -55%; and/or
The mass concentration of the high-valence chromium raw material is 40-60%.
10. The method of claim 6, wherein,
The carrier is one or more selected from silicon dioxide, aluminum oxide, nickel oxide and copper oxide, and the auxiliary agent is one or more selected from cobalt nitrate, manganese chloride, ammonium molybdate and phosphoric acid aqueous solution.
11. The method according to any one of claims 6 to 10, wherein,
In the step 2), the feeding mole ratio of the carrier to the chromium element in the high valence chromium raw material is (1.5-3.2) to 1; and/or
In the step 2), the reaction temperature of the secondary section tubular reactor is 155-170 ℃, the reaction pressure is 10-12 barA, the reaction residence time is 20-40 min, and the flow rate in the reactor is 0.25-0.5 m/min; and a steam jacket is arranged outside the secondary section tubular reactor and is used for system heat preservation.
12. The method according to any one of claims 6 to 10, wherein,
The rotating speed of the shearing disc in the atomizer is 12000-15000 r/min; and/or
The pressure in the drying tower is 50-90 kPaA, and the temperature is 90-150 ℃; and/or
In the step 4), the roasting furnace is continuously operated, the temperature is 400-500 ℃, the residence time is 4-6 h, the air atmosphere is in a pressure of-15 kPaG to-5 kPaG; and/or
The particle diameter D50 of the prepared low-valence chromium-supported catalyst is 50-70 mu m, the abrasion rate is less than 4%, and the yield is more than 70%.
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