JPH0533224B2 - - Google Patents
Info
- Publication number
- JPH0533224B2 JPH0533224B2 JP59065955A JP6595584A JPH0533224B2 JP H0533224 B2 JPH0533224 B2 JP H0533224B2 JP 59065955 A JP59065955 A JP 59065955A JP 6595584 A JP6595584 A JP 6595584A JP H0533224 B2 JPH0533224 B2 JP H0533224B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- reactor
- melamine
- perforated plate
- solid acid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 239000003054 catalyst Substances 0.000 claims description 45
- 229920000877 Melamine resin Polymers 0.000 claims description 15
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 claims description 15
- 239000011973 solid acid Substances 0.000 claims description 12
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 11
- 239000004202 carbamide Substances 0.000 claims description 11
- 238000000034 method Methods 0.000 claims description 7
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 4
- 238000004519 manufacturing process Methods 0.000 claims description 3
- 230000002194 synthesizing effect Effects 0.000 claims description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 10
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 229910021529 ammonia Inorganic materials 0.000 description 3
- 239000007809 chemical reaction catalyst Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- QDOXWKRWXJOMAK-UHFFFAOYSA-N dichromium trioxide Chemical compound O=[Cr]O[Cr]=O QDOXWKRWXJOMAK-UHFFFAOYSA-N 0.000 description 2
- 239000000395 magnesium oxide Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 238000007873 sieving Methods 0.000 description 2
- 239000005909 Kieselgur Substances 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000000440 bentonite Substances 0.000 description 1
- 229910000278 bentonite Inorganic materials 0.000 description 1
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 229910052622 kaolinite Inorganic materials 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- 239000011949 solid catalyst Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/1818—Feeding of the fluidising gas
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/18—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles
- B01J8/24—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with fluidised particles according to "fluidised-bed" technique
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2208/00—Processes carried out in the presence of solid particles; Reactors therefor
- B01J2208/00008—Controlling the process
- B01J2208/00017—Controlling the temperature
- B01J2208/00106—Controlling the temperature by indirect heat exchange
- B01J2208/00115—Controlling the temperature by indirect heat exchange with heat exchange elements inside the bed of solid particles
- B01J2208/00141—Coils
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
Description
【発明の詳細な説明】
本発明はメラミンの製造法に関するものであ
る。
アンモニア雰囲気中で粒状または粉状の固体酸
触媒の存在下、流動層反応により尿素および／ま
たはその熱分解生成物からメラミンを合成する方
法は知られている。従来、合成において使用され
た固体酸触媒は経時的に尿素のメラミンへの転化
率および製品メラミンの品質を低下させるとう欠
点を有しており、この劣化した触媒は水蒸気を含
む酸素と高温で接触させ、付着有機物を燃焼除去
して再生し使用されていた（特開昭54−22385
号）。ところで、流動層反応器においては、反応
器下部から導入するガスの反応器への分散を良好
にし、また触媒の反応器下部への沈積を防ぐため
に、反応器下部に多孔板が設置されている。
しかしながら、実際には反応の経過につれて多
孔板の下に触媒が落下し蓄積する。この落下し蓄
積した回収触媒は、一部が塊状化しており、その
ままでは再生使用も不可能である。
本発明者等はこの多孔板下部に蓄積した回収触
媒の再利用について鋭意研究したところ、驚くべ
きことに多孔板の下部に蓄積した回収触媒から塊
状物を除去すれば、得られた粒状または粉状固体
酸触媒は何ら再生処理することなく、そのまま反
応触媒として使用することができることを見出
し、本発明を完成した。
すなわち、本発明は尿素および／またはその熱
分解生成物から粒状または粉状の固体酸触媒の存
在下、反応器下部に多孔板を備えた流動層反応器
を用いてメラミンを合成する方法に於いて、反応
器の多孔板の下部に蓄積した回収触媒から、塊状
物を除去した粒状または粉状固体酸触媒の全部ま
たは一部を反応器に供給することを特徴とするも
のである。
以下、本発明を図面により説明する。
第１図は本発明の反応器を模式的に示す図であ
る。反応器１には固体酸触媒５が装入されてい
る。本発明で用いる固体酸触媒としては、活性ア
ルミナ、シリカゲル、シリカアルミナ、シリカマ
グネシア、マグネシア、クロミア、クロミアアル
ミナ、シリカジルコニア、アルミナボリア、チタ
ニアボリア、ゼオライト、酸性白土、モンモリロ
ナイト、カオリナイト、ベントナイト、珪藻土リ
ン酸、シリカリン酸等が用いられる。触媒の形状
は粒状または粉状であればよい。
この固体触媒は反応器下部ノズル８から導入さ
れるアンモニア、炭酸ガスから成る混合ガスによ
り流動化される。反応器下部でガス導入口もとの
まゝ上部に設置された多孔板２は触媒が反応器下
部へ落下することを防ぐ為のものであるが、ガス
流通の為の微細な穴が多数設けられている。メラ
ミン合成に際しての反応器内部温度は300〜400℃
が好適である。尿素および／またはその熱分解生
成物がライン７から反応器に導入される。尿素お
よび／またはその熱分解物は、通常、尿素を溶融
し流動状態にしたものが使用される。反応器内で
尿素はメラミンへ転化し反応器上部からサイクロ
ンで触媒と分離されて取り出される。
反応器内で流動している触媒の大部分は多孔板
２の上部に存在しているが、反応の経過に伴い一
部の触媒が多孔板の穴を通して反応器下部６に蓄
積して回収される。蓄積した回収触媒は部分的に
固つた塊状物を含有している。本発明の方法では
この蓄積した回収触媒を取り出し、塊状物を除去
して得られた粒状または粉状固体酸の全部または
一部を反応触媒として循環使用する。回収触媒か
ら塊状物を除去する手段としては通常の篩分けの
手段で良い。また除去する塊状物は反応条件下に
於て流動状態を形成しない粒径が３〜４mm以上の
粗粒を篩分けして除去する。
塊状物を除去した粒状または粉状の固体酸触媒
の再使用は、新しく実施する反応の反応触媒とし
て反応器に加えられる触媒の５〜40重量部、好ま
しくは10〜25重量部程度である。
また、多孔板の下部に回収される触媒を連続ま
たは間欠的に取出し、回収触媒から塊状物を除去
し、新規触媒と合わして反応系に不足する触媒量
を連続的に補給しながら反応を実施することもで
きる。
本発明の方法によれば、従来、反応器下部多孔
板の下に蓄積し回収された触媒から、塊状物を単
に物理的に除去したものが何ら再生処理すること
なく、新しい触媒あるいは再生処理した触媒と全
く同等の性能を発現するので、経時的に劣化した
触媒全てを再生処理する必要がなくなり、メラミ
ン製造工程が簡略化され、また触媒原単位が向上
するという効果をもたらす。
次に実施例により本発明の方法を更に詳しく説
明する。
実施例 １
内径８ｍ高さ17ｍの流動層反応器１に径0.1〜
0.5mmのγ−アルミナ触媒250tを充填し、アンモ
ニア70容量％、炭酸ガス30容量％からなる混合ガ
スを毎時32000m3通じて流動化させ390℃の反応温
度で毎時13tの溶融尿素を反応器に供給し１ケ月
間連続運転を行なつた。運転を止めて反応器多孔
板下の反応器下部に触媒が50t蓄積していた。触
媒の一部は固つていた。この下部に蓄積した触媒
を取り出し６メツシユの篩で振つて塊状物を除い
た。塊状物が除かれた触媒量は26tであつた。こ
の触媒を10t反応器の触媒層に供給した。メラミ
ン合成反応を再開し同様の条件で反応させたとこ
ろ新規の触媒を用いた場合と全く同等の性能を有
することが確認された。尿素のメラミンへの転化
率および製品メラミンの樹脂化速度の経時変化を
第１表に示す。参考例１は全量新規触媒を用いた
場合を示した。
【表】DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing melamine. A method of synthesizing melamine from urea and/or its thermal decomposition products by a fluidized bed reaction in the presence of a granular or powdered solid acid catalyst in an ammonia atmosphere is known. Traditionally, solid acid catalysts used in synthesis have the disadvantage of decreasing the conversion rate of urea to melamine and the quality of the product melamine over time, and this deteriorated catalyst is exposed to oxygen containing water vapor at high temperatures. It was recycled and used by burning off the attached organic matter (Japanese Patent Application Laid-Open No. 1983-22385).
issue). By the way, in a fluidized bed reactor, a perforated plate is installed at the bottom of the reactor in order to improve the dispersion of the gas introduced from the bottom of the reactor into the reactor and to prevent the catalyst from depositing at the bottom of the reactor. . However, in reality, as the reaction progresses, the catalyst falls and accumulates under the porous plate. Part of the recovered catalyst that has fallen and accumulated has become agglomerated, and it is impossible to reuse it as it is. The present inventors conducted intensive research on the reuse of the recovered catalyst accumulated at the bottom of the perforated plate, and surprisingly found that if the lumps were removed from the recovered catalyst accumulated at the bottom of the perforated plate, the resulting granules or powder The present invention was completed based on the discovery that the solid acid catalyst can be used as a reaction catalyst as it is without any regeneration treatment. That is, the present invention is a method for synthesizing melamine from urea and/or its thermal decomposition products in the presence of a granular or powdery solid acid catalyst using a fluidized bed reactor equipped with a perforated plate at the bottom of the reactor. The method is characterized in that all or part of the granular or powdery solid acid catalyst from which lumps have been removed is supplied to the reactor from the recovered catalyst accumulated in the lower part of the porous plate of the reactor. Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a diagram schematically showing a reactor of the present invention. A solid acid catalyst 5 is charged into the reactor 1 . The solid acid catalyst used in the present invention includes activated alumina, silica gel, silica alumina, silica magnesia, magnesia, chromia, chromia alumina, silica zirconia, alumina boria, titania boria, zeolite, acid clay, montmorillonite, kaolinite, bentonite, diatomaceous earth phosphorus. Acid, silica phosphoric acid, etc. are used. The shape of the catalyst may be granular or powder. This solid catalyst is fluidized by a mixed gas consisting of ammonia and carbon dioxide introduced from the lower nozzle 8 of the reactor. The perforated plate 2 installed above the gas inlet at the bottom of the reactor is intended to prevent the catalyst from falling to the bottom of the reactor, but it also has many fine holes for gas circulation. There is. The internal temperature of the reactor during melamine synthesis is 300-400℃
is suitable. Urea and/or its pyrolysis products are introduced into the reactor via line 7. Urea and/or its thermal decomposition products are usually used in the form of molten urea in a fluidized state. In the reactor, urea is converted to melamine, which is separated from the catalyst by a cyclone and taken out from the top of the reactor. Most of the catalyst flowing in the reactor is present in the upper part of the perforated plate 2, but as the reaction progresses, some of the catalyst passes through the holes in the perforated plate and accumulates in the lower part 6 of the reactor and is collected. Ru. The accumulated recovered catalyst contains partially solidified agglomerates. In the method of the present invention, the accumulated recovered catalyst is taken out, the lumps are removed, and all or part of the granular or powdery solid acid obtained is recycled and used as a reaction catalyst. As a means for removing lumps from the recovered catalyst, ordinary sieving may be used. The lumps to be removed are removed by sieving coarse particles having a particle size of 3 to 4 mm or more that do not form a fluidized state under the reaction conditions. The granular or powdered solid acid catalyst from which lumps have been removed can be reused in an amount of about 5 to 40 parts by weight, preferably 10 to 25 parts by weight, of the catalyst added to the reactor as a reaction catalyst for a newly conducted reaction. In addition, the catalyst recovered at the bottom of the perforated plate is taken out continuously or intermittently, lumps are removed from the recovered catalyst, and the reaction is carried out while continuously replenishing the insufficient amount of catalyst in the reaction system by combining it with new catalyst. You can also. According to the method of the present invention, lumps are simply physically removed from the catalyst that has conventionally been accumulated and recovered under the perforated plate at the bottom of the reactor. Since it exhibits exactly the same performance as a catalyst, there is no need to regenerate all the catalysts that have deteriorated over time, which simplifies the melamine production process and improves the catalyst consumption rate. Next, the method of the present invention will be explained in more detail with reference to Examples. Example 1 A fluidized bed reactor 1 with an inner diameter of 8 m and a height of 17 m has a diameter of 0.1~
Filled with 250 tons of 0.5 mm γ-alumina catalyst, a mixed gas consisting of 70% by volume of ammonia and 30 % by volume of carbon dioxide was fluidized through 32,000 m3 per hour, and 13 tons of molten urea per hour was fed into the reactor at a reaction temperature of 390°C. It was supplied and operated continuously for one month. Operation was stopped and 50 tons of catalyst had accumulated at the bottom of the reactor under the reactor's perforated plate. Part of the catalyst was solidified. The catalyst accumulated in the lower part was taken out and sieved through a 6-mesh sieve to remove lumps. The amount of catalyst from which lumps were removed was 26 tons. This catalyst was supplied to the catalyst bed of a 10t reactor. When the melamine synthesis reaction was restarted under the same conditions, it was confirmed that the melamine synthesis reaction had exactly the same performance as when using the new catalyst. Table 1 shows changes over time in the conversion rate of urea to melamine and the rate of resinization of the product melamine. Reference Example 1 shows the case where the new catalyst was used entirely. 【table】
第１図は、本発明に係るメラミン製造用反応器
の１例を断面図で示す。図中、各符号はそれぞれ
次を示す。
１……反応器、２……多孔板、３……サイクロ
ン、４……スパージヤー、５……触媒流動層、６
……反応器下部、７……尿素供給ライン、８……
反応器下部ノヅル、９……加熱コイル、１０……
反応器出口ライン。
FIG. 1 shows a cross-sectional view of an example of a reactor for producing melamine according to the present invention. In the figure, each symbol indicates the following. 1... Reactor, 2... Perforated plate, 3... Cyclone, 4... Spargeer, 5... Catalyst fluidized bed, 6
... lower part of the reactor, 7 ... urea supply line, 8 ...
Reactor lower nozzle, 9... Heating coil, 10...
Reactor outlet line.
Claims (1)
状または粉状の固体酸触媒の存在下、反応器下部
に多孔板を備えた流動層反応器を用いてメラミン
を合成する方法に於いて、反応器の多孔板の下部
に回収された固体酸触媒から塊状物を除去して再
使用することを特徴とするメラミンの製造方法。1. In a method for synthesizing melamine from urea and/or its thermal decomposition products in the presence of a granular or powdery solid acid catalyst using a fluidized bed reactor equipped with a perforated plate at the bottom of the reactor, the reactor A method for producing melamine, which comprises removing lumps from a solid acid catalyst collected at the bottom of a perforated plate and reusing the solid acid catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6595584A JPS60209575A (en) | 1984-04-04 | 1984-04-04 | Preparation of melamine |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6595584A JPS60209575A (en) | 1984-04-04 | 1984-04-04 | Preparation of melamine |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60209575A JPS60209575A (en) | 1985-10-22 |
| JPH0533224B2 true JPH0533224B2 (en) | 1993-05-19 |
Family
ID=13301912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6595584A Granted JPS60209575A (en) | 1984-04-04 | 1984-04-04 | Preparation of melamine |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60209575A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5867341A (en) * | 1981-09-26 | 1983-04-21 | バスフ アクチエンゲゼルシヤフト | Improvement of melamine quality by reactivating catalyst used in melamine synthesis |
-
1984
- 1984-04-04 JP JP6595584A patent/JPS60209575A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5867341A (en) * | 1981-09-26 | 1983-04-21 | バスフ アクチエンゲゼルシヤフト | Improvement of melamine quality by reactivating catalyst used in melamine synthesis |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60209575A (en) | 1985-10-22 |
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