CN1723203A - Two-stage reactor for the production of melamine - Google Patents
Two-stage reactor for the production of melamine Download PDFInfo
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- CN1723203A CN1723203A CN 200480002014 CN200480002014A CN1723203A CN 1723203 A CN1723203 A CN 1723203A CN 200480002014 CN200480002014 CN 200480002014 CN 200480002014 A CN200480002014 A CN 200480002014A CN 1723203 A CN1723203 A CN 1723203A
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- 229920000877 Melamine resin Polymers 0.000 title abstract description 7
- 238000004519 manufacturing process Methods 0.000 title abstract description 6
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 title abstract description 6
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 15
- 239000004202 carbamide Substances 0.000 claims abstract description 15
- 239000011949 solid catalyst Substances 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 45
- 238000006243 chemical reaction Methods 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 18
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 13
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 13
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 230000001413 cellular effect Effects 0.000 claims description 12
- 229910052500 inorganic mineral Inorganic materials 0.000 claims description 11
- 239000011707 mineral Substances 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 10
- OWIKHYCFFJSOEH-UHFFFAOYSA-N Isocyanic acid Chemical compound N=C=O OWIKHYCFFJSOEH-UHFFFAOYSA-N 0.000 claims description 9
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 7
- 238000001321 HNCO Methods 0.000 claims description 4
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 4
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical class O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 4
- FAHBNUUHRFUEAI-UHFFFAOYSA-M hydroxidooxidoaluminium Chemical compound O[Al]=O FAHBNUUHRFUEAI-UHFFFAOYSA-M 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 229910001680 bayerite Inorganic materials 0.000 claims description 2
- 229910001593 boehmite Inorganic materials 0.000 claims description 2
- 230000003197 catalytic effect Effects 0.000 claims description 2
- 229910001679 gibbsite Inorganic materials 0.000 claims description 2
- 238000000691 measurement method Methods 0.000 claims description 2
- 239000010445 mica Substances 0.000 claims description 2
- 229910052618 mica group Inorganic materials 0.000 claims description 2
- 239000008188 pellet Substances 0.000 claims description 2
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 abstract description 22
- 238000000354 decomposition reaction Methods 0.000 abstract description 3
- 230000009466 transformation Effects 0.000 description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 8
- 230000002779 inactivation Effects 0.000 description 8
- 230000015572 biosynthetic process Effects 0.000 description 6
- 230000009849 deactivation Effects 0.000 description 6
- 230000008021 deposition Effects 0.000 description 6
- 239000007789 gas Substances 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical group [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 4
- XLJMAIOERFSOGZ-UHFFFAOYSA-N anhydrous cyanic acid Natural products OC#N XLJMAIOERFSOGZ-UHFFFAOYSA-N 0.000 description 4
- 239000013049 sediment Substances 0.000 description 4
- 238000007669 thermal treatment Methods 0.000 description 4
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000005033 Fourier transform infrared spectroscopy Methods 0.000 description 2
- 239000002841 Lewis acid Substances 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 229910000323 aluminium silicate Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000007859 condensation product Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 150000007517 lewis acids Chemical class 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 150000003222 pyridines Chemical class 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- JYEUMXHLPRZUAT-UHFFFAOYSA-N 1,2,3-triazine Chemical group C1=CN=NN=C1 JYEUMXHLPRZUAT-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 239000004640 Melamine resin Substances 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- YKTSYUJCYHOUJP-UHFFFAOYSA-N [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] Chemical compound [O--].[Al+3].[Al+3].[O-][Si]([O-])([O-])[O-] YKTSYUJCYHOUJP-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- VBIXEXWLHSRNKB-UHFFFAOYSA-N ammonium oxalate Chemical compound [NH4+].[NH4+].[O-]C(=O)C([O-])=O VBIXEXWLHSRNKB-UHFFFAOYSA-N 0.000 description 1
- 229940111121 antirheumatic drug quinolines Drugs 0.000 description 1
- 150000001538 azepines Chemical class 0.000 description 1
- 125000002915 carbonyl group Chemical group [*:2]C([*:1])=O 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000003421 catalytic decomposition reaction Methods 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000005243 fluidization Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 239000004922 lacquer Substances 0.000 description 1
- YSRVJVDFHZYRPA-UHFFFAOYSA-N melem Chemical compound NC1=NC(N23)=NC(N)=NC2=NC(N)=NC3=N1 YSRVJVDFHZYRPA-UHFFFAOYSA-N 0.000 description 1
- 150000001457 metallic cations Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 239000006259 organic additive Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- XDJOIMJURHQYDW-UHFFFAOYSA-N phenalene Chemical compound C1=CC(CC=C2)=C3C2=CC=CC3=C1 XDJOIMJURHQYDW-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 150000003248 quinolines Chemical class 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 150000003376 silicon Chemical class 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 229960001866 silicon dioxide Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 238000005829 trimerization reaction Methods 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D251/00—Heterocyclic compounds containing 1,3,5-triazine rings
- C07D251/02—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings
- C07D251/12—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members
- C07D251/26—Heterocyclic compounds containing 1,3,5-triazine rings not condensed with other rings having three double bonds between ring members or between ring members and non-ring members with only hetero atoms directly attached to ring carbon atoms
- C07D251/40—Nitrogen atoms
- C07D251/54—Three nitrogen atoms
- C07D251/56—Preparation of melamine
- C07D251/60—Preparation of melamine from urea or from carbon dioxide and ammonia
Abstract
Production of melamine by urea decomposition using a solid catalyst takes place in a main reactor containing a catalyst of low Lewis acidity and a post-reactor containing a catalyst of the same or higher (especially higher) Lewis acidity.
Description
The present invention relates to a kind of method for preparing trimeric cyanamide by the catalytic decomposition urea.Method of the present invention is a two-step approach, wherein adopts the catalyzer with different acidity in two steps.
The trimeric cyanamide that structure is represented by following formula I is used for the preparation melamine resin with the compound reaction that contains carbonyl.This resin especially can be used as plastics and is used for coating and lacquer.It is a kind of known reaction that decomposition by urea prepares trimeric cyanamide, and chemical industry is used this reaction according to many different schemes.On principle, divide into high-pressure process and low-pressure process.High-pressure process the pressure (absolute pressure) of＞about 80 crust and＞370 ℃ temperature and do not have to carry out under the condition of catalyzer.
Yet among the present invention set forth herein, the low-pressure process of carrying out under the temperature of the pressure (absolute pressure) of about 1-10 crust and 370-430 ℃ has more importance.Known this reaction was carried out with two steps.In the first step heat absorption step, urea reacts and forms ammonia and isocyanic acid, and isocyanic acid forms trimeric cyanamide and emits CO in the second step heat release step
2Following reaction formula has been described each autoreaction.
Low-pressure process has three kinds of main schemes, below more specifically describes.
In the Linz-Chemie method, reaction was carried out with two steps.In the first step, the fused urea at 350 ℃ and 3.5 crust (absolute pressure) thus under decompose in the fluidized-bed at sand and form ammonia and isocyanic acid.Isocyanic acid is catalytically conveted to trimeric cyanamide in fixed-bed reactor under 450 ℃ and normal atmosphere subsequently.This catalyzer is aluminium oxide catalyst normally.
The DSM-Stamicarbon method is the single stage method of carrying out under about 7 crust (absolute pressure).Used catalyzer is the pure aluminium silicate that uses as fluidized-bed.Fluidizing agent is that waste gas is carried out aftertreatment and the pure ammonia that reclaims.
Be the BASF method at last.Here, reaction also is to carry out under low pressure (absolute pressures of about 2 crust) in the fluidized-bed that adopts aluminum oxide or alumina/silica catalyzer.The gas that is used for fluidized-bed is the gas that reclaims from reactor, and this gas comprises NH
3And CO
2And the molten urea that has utilized in advance usually absorption impurity is handled and has been removed impurity.
Aforesaid method is compared with the on-catalytic method has the simpler and more cheap advantage of equipment on principle, but often goes wrong when carrying out above-mentioned all catalysis process, and promptly the product that the trimeric cyanamide condensation level is higher is deposited on the surface of catalyzer (coating).Here can mention melem (C
6H
6N
10, 2,5,8-triamino-1,3,4,6,7,9, non-those quinolines of 9b-seven azepines (phenalene)) example, this compound is the tricyclic compound that is made of three condensed triazine rings.The excess deposition of condensation product is related to the inactivation of catalyzer, and for example requires to handle and catalyzer is regenerated by thermal treatment and/or with steam, air or ammonia, and also needs more catalyst changeout in severe case.In addition, because the deposition of condensation product on catalyzer carry out comparatively fast forming the stable state concentration of these products, thus the inactivation of catalyzer takes place after the very short time usually, so that, make the regular regeneration of catalyzer infeasible because the timed interval is short.
In order to realize high yield or than the decomposition of low degree, at present also not about the catalyzer of production of melamine the character that must have and the systematic study or the knowledge of composition aspect.
JP-A 08 027 126 asks for protection a kind of γ-Al that is used for production of melamine with specific acidity interval
2O
3Catalyzer.
The active catalyst that Thianranqi Huagong, 2001,26 volumes, 23-25 page or leaf (quoting based on CA 136:135396) disclose production of melamine can pass through to mix Al
2O
3With zeolite or contain the zeolite of metallic cation and obtain.The activity that obtains is owing to the acid site of catalyzer.
Yet, have been found that and use the catalyzer of acidity can not solve catalyst deactivation with increase, particularly form catalyst deactivation and related with it low-conversion problem that deposition causes.
The purpose of this invention is to provide a kind of method, utilize this method, especially under selected reaction conditions, can obtain high conversion and trimeric cyanamide productive rate and do not form the too early inactivation of the catalyzer that deposition causes.
We find to use main reactor and post-reactor to decompose urea on solid catalyst and the method for catalytic preparation trimeric cyanamide can realize this purpose by a kind of, the catalyzer that lewis acidity is low is used for main reactor in the method, equates or the catalyzer of higher lewis acidity is used for post-reactor and have.
The present invention is based on such understanding: although use the higher catalyzer of lewis acidity produced the urea raw material to the high conversion of trimeric cyanamide and thereby cause high reaction yield, on catalyst system therefor, form deposition and also take place comparatively fast.Therefore the catalyst deactivation that formation deposition causes has surmounted required high conversion effect rapidly.
Because the whole bag of tricks expense height of avoiding or reverse formation of deposits taked, and in addition, the very fast generation of sedimentary formation finds that it is favourable independently carrying out the synthetic of trimeric cyanamide in the reactor (main reactor and post-reactor) at two.In main reactor, adopt the low catalyzer of lewis acidity, produce relatively low transformation efficiency and also produce lower formation of deposits degree.In post-reactor, adopt lewis acidity to equate or higher catalyzer.Catalyzer in post-reactor preferably has higher lewis acidity, and this can realize very high transformation efficiency.So just can realize high whole transformation efficiency, the while can also be realized the low inactivation of two kinds of catalyzer adopting in main reactor and the post-reactor.
In main reactor, the reaction that urea is decomposed to form isocyanic acid and trimerization formation trimeric cyanamide all takes place, but particularly second reaction only not exclusively carried out, can exist with any form well known by persons skilled in the art on the catalyzer principle, for example as fixed bed, fluidized-bed, circulating fluidized bed or moving-bed.Catalyzer in the main reactor preferably uses with fluidized-bed.
The catalyzer that adopts in the main reactor preferably comprises at least a mineral that are selected from the mixture of aluminum oxide, silicon oxide and silico-aluminate and various aluminum oxide, silicon oxide and/or silico-aluminate.Especially preferably comprise at least a mineral that are selected from bayerite, boehmite, gibbsite, polynite, wilkinite and white mica, particularly wilkinite.Described catalyzer can be fully by above-mentioned mineral composition.
Above-mentioned mineral can for example activate to obtain required acidity by thermal treatment according to method known to those skilled in the art before use.Because thermal treatment increases the acidity of described mineral usually, does not heat-treat usually under the situation of the catalyzer that is adopted in main reactor.
The catalyzer that adopts in the main reactor preferably has 0.3-1.8 μ mol/g, more preferably the surperficial lewis acidity of 0.5-1.5 μ mol/g, particularly 0.8-1.2 μ mol/g.Here the numerical value of Xian Shiing is by using pyridines to obtain as the acidity measurement of probe molecule in high vacuum Fourier transform infrared spectroscopy (HV-FTIR) at 390 ℃, and the Lewis acid centers that is characterized by different IR absorption bands is by quantitatively determining the peak area integration.Turk.J.Chem.23 (1999), the method for describing in the 319-327 page or leaf is used for this purpose.Be to measure this numerical value under the situation of 5.1mm in the shelf inner diameter of compressing tablet catalyzer.
Typical fluid catalyst has 50-350m
2/ g, preferred 100-250m
2The BET surface-area of/g.Pore volume is in the 0.1-1.0ml/g scope.The median size of catalyzer is 10-500 μ m.
The condition of implementing method of the present invention in the presence of this special catalyst is: temperature is 350-450 ℃, preferred 380-420 ℃, absolute pressure is the 1-15 crust, preferred 1-10 crust, 5-8 crust particularly, the residence time on fluidized-bed is 1-50 second, preferred 2-30 second, and the air speed on the catalyzer is 20-700kg urea/t (catalyzer) h, preferred 50-500kg urea/t (catalyzer) h.
It is cylindrical or conical that main reactor is generally.In one embodiment of the invention, the fluidized-bed reactor that adopts as main reactor has conical structure.This has formed the increase of inflow gas speed and thereby has formed more stable fluidizing performance.
The 1.5-6 of the catalyzer that the surperficial lewis acidity of the dimension criteriaization that the catalyzer that uses in post-reactor has under reaction conditions preferably uses in the main reactor doubly, more preferably 3-5 is doubly.
The surface acidity of the catalyzer that adopts in the post-reactor is preferably 2-12 μ m/g, more preferably 3-10 μ m/g, particularly 3.5-6 μ m/g.Numerical value given here is by using pyridines to obtain as the acidity measurement of probe molecule in high vacuum Fourier transform infrared spectroscopy (HV-FTIR) at 390 ℃, and the Lewis acid centers that is characterized by different IR absorption bands is by quantitatively determining the peak area integration.Adopt Turk.J.Chem.23 (1999), the method for describing in the 319-327 page or leaf is used for this purpose.Be to determine this numerical value under the situation of 5.1mm in the shelf inner diameter of compressing tablet catalyzer.
The same with the catalyzer that adopts in the main reactor, the catalyzer that adopts in post-reactor preferably comprises at least a mineral that are selected from the mixture of aluminum oxide, silicon oxide and silico-aluminate and aluminum oxide, silicon oxide and/or silico-aluminate.The catalyzer that adopts in the post-reactor comprises 0-60 weight %, the SiO of preferred 5-50 weight %
2, and 100-40 weight %, the Al of preferred 95-50 weight %
2O
3The preferred aluminosilicate catalyst that adopts.
The BET surface-area of catalyzer is 150-400m
2/ g, preferred 200-350m
2/ g.
The known various necessary desired methods of acidity that obtain of those skilled in the art.Can introduce given mineral (for example silicon-dioxide in aluminum oxide) and/or obtain required acidity by having different valent ions by thermal treatment.In a preferred embodiment of the invention, before use by at 350-950 ℃, heat-treat under preferred 450-750 ℃ and activate described mineral.
The pore volume of catalyzer is 0.1-1.5ml/g, preferred 0.2-0.9ml/g (N
2), or 0.1-2.0ml/g, preferred 0.2-1.0ml/g (Hg porosity measurement method).The aperture is 10-100 , preferred 30-90 .
The condition of carrying out the inventive method in post-reactor is: the residence time is 0.1-20 second, preferred 0.5-10 second, air speed in post-reactor on the catalyzer is 0.05-2g HNCO/g (catalyzer) h, preferred 0.1-1g HNCO/g (catalyzer) h, temperature is 350-500 ℃, and preferred 390-450 ℃, absolute pressure is the 1-15 crust, preferred 1-10 crust, particularly 5-8 crust.
In post-reactor, catalyzer can exist by suitable form well known by persons skilled in the art, for example as fixed bed or fluidized-bed.The catalyst mode that discovery permission in post-reactor takes place in reaction process than the backmixing of low degree is favourable.Be exactly this situation for example, thereby preferably in post-reactor, use fixed bed catalyst for fixed bed catalyst.Fixed bed catalyst advantageously exists as formed body.The formed body that can pass from the catalyzer fine solid particle of main reactor is preferred, for example hollow extrudate of described formed body, material all in one piece, star extrudate, pellet or crushing material.Useful especially shape is cellular material or hollow extrudate, particularly cellular material.In these formed bodys of mentioning, cellular material has best performance at reactant gases aspect the pressure difference in the process.
Preferably adopt fully by γ-Al
2O
3Constitute or mainly by γ-Al
2O
3The cellular material of forming.γ-Al of preferred 60-100 weight %
2O
3SiO with 0-40 weight %
2The cellular material of forming.
Dry mixed will be shaped to cellular material composition and with preferred nitric acid of peptizing agent and water blending, in pan mill, mix then.Suitable peptizing agent is known to those skilled in the art.If desired, can also adopt the organic additive that does not stay remnants in thermal degradation.Example has carbonate and derivatived cellulose.Concrete example comprises volatile salt, ammonium oxalate and Walocel MT 20.000PV (for example with trade(brand)name Walocel product sold, Wolff Walsrode produces).Composition is extruded under pressure and is obtained required honeycomb geometrical shape then.The drying and moulding body also preferably carries out final roasting under＜600 ℃.
Preferably, thus carrying out the inventive method makes the major portion of conversion occur in the main reactor and makes occurring in the post-reactor than small part (remaining transform) of conversion.
By the following example explanation the present invention.In Reference numeral, A=transformation efficiency [%]; B=organic sediments [weight %]; C=working time [h].
Embodiment
Embodiment 1 (comparative example)
In the pilot reactor of diameter with 80cm and the catalyst bed height of about 8m, under about 400 ℃, urea is converted into trimeric cyanamide.Three kinds of catalyzer (aluminum oxide (catalyzer 2) of the silicon doping aluminum oxide of roasting (catalyzer 1), roasting and the not roasting silico-aluminate (catalyzer 3) of polynite type) of check have the lewis acidity of 4.4,3.6 and 1.0 μ mol/g respectively under reaction conditions.The fluidisation air-flow is about 300 standard m
3/ h.
As can be seen from Figure 1, the initial conversion of the catalyzer of acidity maximum (catalyzer 1) is the highest, is about 90%.Yet, the inactivation of catalyzer only just takes place, and transformation efficiency is reduced to and is lower than 60% after 450 hours after about 250 hours working time.Catalyst deactivation is accompanied by the accumulation of organic sediments on catalyzer, the reason of Here it is catalyst deactivation.
Lewis acidity is that the relatively low acidity catalyzer (catalyzer 2) of 3.6 μ mol/g demonstrates and is approximately 85% low initial transformation efficiency, and this transformation efficiency of formation that is accompanied by organic sediments also reduces (Fig. 2).
Fig. 3 shows the corresponding test (catalyzer 3, lewis acidity only are 1.0 μ mol/g) of using the minimum catalyzer (catalyzer 3) of acidity.This catalyzer only demonstrates about 75% transformation efficiency, but it is worked under the constant transformation efficiency owing to the constant organic sediments.
Guaranteed high conversion, their very fast inactivations although therefore find the high catalyzer of acidity.The catalyst activity of relatively low acidity is lower, but only suffers not serious inactivation.
Embodiment 2
The gas of operating from the employing minimum acidity catalyzer (catalyzer 3) of embodiment 1 that fluidized-bed reactor produced is with 30 standard m
3/ h flow velocity is sent in the fixed bed post-reactor of catalyst bed height of diameter with 13.5cm and 1.5m.
The catalyzer that uses in this fixed bed post-reactor has 95%Al as the hollow extrudate of 10 * 20 * 5mm of silicon doping aluminum oxide, this silicon doping aluminum oxide
2O
3And 5%SiO
2Composition, and extrude the back spend the night 550 ℃ of following roastings.
Under the absolute pressures of about 400 ℃ and 1.5 crust, as can be seen, operating＞1500 hours time and do not have the inactivation of catalyzer under＞90% total conversion rate is possible (Fig. 4).
To contain the main reactor of catalyzer of different acidity and result that post-reactor combines and be the high conversion observed under the highly selective in conjunction with catalyst deactivation than low degree.
The initial conversion and the final transformation efficiency that in embodiment 1 and 2, obtain have been summed up in the following table.
Transformation efficiency among table 1: the embodiment 1 and 2
| Initial conversion (%) | 500h transformation efficiency (%) | |
| Catalyzer 1 | 88 | 56 |
| Catalyzer 2 | 83 | 51 |
| Catalyzer 3 | 73 is constant | |
| Catalyzer 3+ post-reactor | 92 is constant | |
Embodiment 3
Dry mixed 3kg is by 5%SiO
2Material of forming with 95% aluminum oxyhydroxide and 7kg are by 5%SiO
2With 95% γ-Al
2O
3The material of forming 5 minutes is at the 69.3% concentration HNO that adds 0.635kg
3After, with the dilution of 2.5kg deionized water, in Mix-Muller, carry out in the blended process deionized water blending with other 4.3kg.
Extrude cellular material under the mold pressings of 50 crust and 20 ℃ temperature, this cellular material has the length of side of 45 * 45mm and the length of 320mm, and having 6 * 6 its interior dimensionss is that 5.7 * 5.7mm, net wall thickness are the channel unit of 1.8mm.This formed body is at room temperature dry.In drying oven, this cellular material was descended dry 24 hours at 30 ℃, carried out the ladder drying until 60 ℃ with 10 ℃ of ladders then, and each ladder continues 24 hours.This cellular material is following dry 24 hours in addition at 60 ℃.This cellular material is finally 500 ℃ of following roastings 7 hours.
Claims (18)
1. one kind is used main reactor and post-reactor to decompose urea and the method for catalytic preparation trimeric cyanamide on solid catalyst, wherein the catalyzer that lewis acidity is low is used for main reactor, equate or higher that the catalyzer of preferred higher lewis acidity is used for post-reactor and have.
2. the method that requires as claim 1, wherein the catalyzer in the main reactor comprises at least a mineral that are selected from aluminum oxide, silicon oxide and silico-aluminate and composition thereof, the preferred at least a mineral that are selected from bayerite, boehmite, gibbsite, polynite, wilkinite and white mica, particularly wilkinite.
3. as claim 1 or 2 methods that require, wherein the catalyzer in the main reactor exists with fluidized-bed.
4. the method that requires as claim 3, wherein main reactor have cylindrical or conical, the preferred conical structure.
5. as the method for any one requirement of claim 1-4, wherein the lewis acidity of the catalyzer that uses in the post-reactor has 1.5-6 doubly under reaction conditions, the dimension criteriaization of preferred 3-5 multiplying factor surface lewis acidity.
6. as the method for any one requirement of claim 1-5, wherein the acidity of the catalyzer that adopts in the main reactor is 0.3-1.8 μ mol/g, preferred 0.5-1.5 μ mol/g, particularly 0.8-1.2 μ mol/g.
7. as the method for any one requirement of claim 1-6, wherein the acidity of the catalyzer that adopts in the post-reactor is 2-12 μ mol/g, more preferably 3-10 μ mol/g, particularly 3.5-6 μ mol/g.
8. as the method for any one requirement of claim 1-7, wherein the catalyzer that adopts in the post-reactor comprises 0-60 weight %, the SiO of preferred 5-50 weight %
2, and 100-40 weight %, the Al of preferred 95-50 weight %
2O
3
9. as the method for any one requirement of claim 1-8, wherein the catalyzer that adopts in the post-reactor comprises at least a mineral that are selected from the mixture of aluminum oxide, silicon oxide and silico-aluminate and aluminum oxide, silicon oxide and/or silico-aluminate, preferably aluminosilicate salt.
10. as the method for any one requirement of claim 1-9, wherein the catalyzer that uses in the post-reactor is before use at 350-950 ℃, activates under preferred 450-750 ℃.
11. as the method for any one requirement of claim 1-10, wherein the BET surface-area of the catalyzer that uses in the post-reactor is 150-400m
2/ g, preferred 200-350m
2/ g.
12. as the method for any one requirement of claim 1-11, wherein the pore volume of catalyzer is 0.1-1.5ml/g, preferred 0.2-0.9ml/g (N
2), or 0.1-2.0ml/g, preferably 0.2-1.0ml/g (Hg porosity measurement method), and aperture is 10-100 , preferred 30-90 .
13. method as any one requirement of claim 1-12, wherein the residence time in post-reactor is 0.1-20 second, preferred 0.5-10 second, and the air speed on catalyzer is 0.05-2g HNCO/g (catalyzer) h, preferred 0.1-1g HNCO/g (catalyzer) h.
14. as the method for any one requirement of claim 1-13, wherein the residence time in main reactor is 1-50 second, preferred 2-30 second, and the air speed on the catalyzer is 20-700kg urea/t (catalyzer) h, preferred 50-500kg urea/t (catalyzer) h.
15. as the method for any one requirement of claim 1-14, wherein the temperature that is reflected in the main reactor is 350-450 ℃, preferred 380-420 ℃, absolute pressure is the 1-15 crust, and preferred 1-10 crust particularly carries out under the condition of 5-8 crust.
16. as the method for any one requirement of claim 1-15, wherein the temperature that is reflected in the post-reactor is 350-500 ℃, preferred 3 90-450 ℃, absolute pressure is the 1-15 crust, and preferred 1-10 crust particularly carries out under the condition of 5-8 crust.
17. as the method for any one requirement of claim 1-16, wherein the catalyzer in the post-reactor exists with fixed bed, is preferably formed body, more preferably material all in one piece, hollow extrudate, star extrudate, pellet or crushing material, particularly cellular material.
18. as the method for any one requirement of claim 1-17, wherein the catalyzer in the main reactor exists with fluidized-bed, the catalyzer in the post-reactor exists with fixed bed.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10301703.8 | 2003-01-17 | ||
| DE2003101703 DE10301703A1 (en) | 2003-01-17 | 2003-01-17 | Melamine production by urea decomposition is effected in main- and post- reactors containing catalysts of different acidity values |
| DE10337501.5 | 2003-08-14 | ||
| DE2003137501 DE10337501A1 (en) | 2003-08-14 | 2003-08-14 | Melamine production by urea decomposition is effected in main- and post- reactors containing catalysts of different acidity values |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1723203A true CN1723203A (en) | 2006-01-18 |
| CN100425597C CN100425597C (en) | 2008-10-15 |
Family
ID=32602668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2004800020141A Expired - Fee Related CN100425597C (en) | 2003-01-17 | 2004-01-16 | Two-stage reactor for the production of melamine |
Country Status (3)
| Country | Link |
|---|---|
| CN (1) | CN100425597C (en) |
| DE (1) | DE10301703A1 (en) |
| MY (1) | MY141592A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100388972C (en) * | 2006-05-16 | 2008-05-21 | 梁振玉 | Production process of alumina catalyst for producing melamine |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110665521A (en) * | 2019-10-29 | 2020-01-10 | 青岛惠城环保科技股份有限公司 | Catalyst for synthesizing melamine and preparation method thereof |
| CN113694911A (en) * | 2021-09-16 | 2021-11-26 | 四川金象赛瑞化工股份有限公司 | Catalyst for synthesizing melamine and preparation method thereof |
| CN113694912A (en) * | 2021-09-16 | 2021-11-26 | 四川金象赛瑞化工股份有限公司 | Catalyst for melamine production and preparation method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL9002606A (en) * | 1990-11-29 | 1992-06-16 | Stamicarbon | PROCESS FOR THE PREPARATION OF MELAMINE FROM UREA. |
| RU2252216C2 (en) * | 1999-07-27 | 2005-05-20 | Агролинц Меламин Гмбх | Method for melamine treatment obtained by synthesis in high- pressure reactor |
-
2003
- 2003-01-17 DE DE2003101703 patent/DE10301703A1/en not_active Withdrawn
-
2004
- 2004-01-16 CN CNB2004800020141A patent/CN100425597C/en not_active Expired - Fee Related
- 2004-01-16 MY MYPI20040126 patent/MY141592A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100388972C (en) * | 2006-05-16 | 2008-05-21 | 梁振玉 | Production process of alumina catalyst for producing melamine |
Also Published As
| Publication number | Publication date |
|---|---|
| DE10301703A1 (en) | 2004-07-29 |
| MY141592A (en) | 2010-05-14 |
| CN100425597C (en) | 2008-10-15 |
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