JPH0357887B2 - - Google Patents
Info
- Publication number
- JPH0357887B2 JPH0357887B2 JP57200582A JP20058282A JPH0357887B2 JP H0357887 B2 JPH0357887 B2 JP H0357887B2 JP 57200582 A JP57200582 A JP 57200582A JP 20058282 A JP20058282 A JP 20058282A JP H0357887 B2 JPH0357887 B2 JP H0357887B2
- Authority
- JP
- Japan
- Prior art keywords
- terephthalic acid
- temperature
- oxidation
- reactor
- reaction
- 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
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 claims description 82
- 238000007254 oxidation reaction Methods 0.000 claims description 52
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 39
- URLKBWYHVLBVBO-UHFFFAOYSA-N Para-Xylene Chemical group CC1=CC=C(C)C=C1 URLKBWYHVLBVBO-UHFFFAOYSA-N 0.000 claims description 34
- 239000000203 mixture Substances 0.000 claims description 19
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 17
- 229910001882 dioxygen Inorganic materials 0.000 claims description 17
- 238000000034 method Methods 0.000 claims description 17
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 claims description 15
- 239000002904 solvent Substances 0.000 claims description 15
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 13
- 229910052794 bromium Inorganic materials 0.000 claims description 13
- 238000011282 treatment Methods 0.000 claims description 13
- 229910001385 heavy metal Inorganic materials 0.000 claims description 11
- 230000001590 oxidative effect Effects 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 239000011541 reaction mixture Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 4
- 238000000926 separation method Methods 0.000 claims description 3
- 238000010924 continuous production Methods 0.000 claims description 2
- 239000003054 catalyst Substances 0.000 description 25
- 230000003647 oxidation Effects 0.000 description 21
- 238000006243 chemical reaction Methods 0.000 description 15
- 239000012452 mother liquor Substances 0.000 description 8
- 239000007789 gas Substances 0.000 description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 239000000543 intermediate Substances 0.000 description 4
- 229920000728 polyester Polymers 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 229910017052 cobalt Inorganic materials 0.000 description 3
- 239000010941 cobalt Substances 0.000 description 3
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000010992 reflux Methods 0.000 description 3
- 238000010405 reoxidation reaction Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- GOUHYARYYWKXHS-UHFFFAOYSA-N 4-formylbenzoic acid Chemical compound OC(=O)C1=CC=C(C=O)C=C1 GOUHYARYYWKXHS-UHFFFAOYSA-N 0.000 description 2
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 150000001869 cobalt compounds Chemical class 0.000 description 2
- BZRRQSJJPUGBAA-UHFFFAOYSA-L cobalt(ii) bromide Chemical compound Br[Co]Br BZRRQSJJPUGBAA-UHFFFAOYSA-L 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- RJYMRRJVDRJMJW-UHFFFAOYSA-L dibromomanganese Chemical compound Br[Mn]Br RJYMRRJVDRJMJW-UHFFFAOYSA-L 0.000 description 2
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000003631 expected effect Effects 0.000 description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 150000002697 manganese compounds Chemical class 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000012066 reaction slurry Substances 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- BMYNFMYTOJXKLE-UHFFFAOYSA-N 3-azaniumyl-2-hydroxypropanoate Chemical compound NCC(O)C(O)=O BMYNFMYTOJXKLE-UHFFFAOYSA-N 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- 229940011182 cobalt acetate Drugs 0.000 description 1
- ZBYYWKJVSFHYJL-UHFFFAOYSA-L cobalt(2+);diacetate;tetrahydrate Chemical compound O.O.O.O.[Co+2].CC([O-])=O.CC([O-])=O ZBYYWKJVSFHYJL-UHFFFAOYSA-L 0.000 description 1
- QAHREYKOYSIQPH-UHFFFAOYSA-L cobalt(II) acetate Chemical compound [Co+2].CC([O-])=O.CC([O-])=O QAHREYKOYSIQPH-UHFFFAOYSA-L 0.000 description 1
- 239000006103 coloring component Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 229910000042 hydrogen bromide Inorganic materials 0.000 description 1
- 229940071125 manganese acetate Drugs 0.000 description 1
- 229940082328 manganese acetate tetrahydrate Drugs 0.000 description 1
- UOGMEBQRZBEZQT-UHFFFAOYSA-L manganese(2+);diacetate Chemical compound [Mn+2].CC([O-])=O.CC([O-])=O UOGMEBQRZBEZQT-UHFFFAOYSA-L 0.000 description 1
- CESXSDZNZGSWSP-UHFFFAOYSA-L manganese(2+);diacetate;tetrahydrate Chemical compound O.O.O.O.[Mn+2].CC([O-])=O.CC([O-])=O CESXSDZNZGSWSP-UHFFFAOYSA-L 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- SGGOJYZMTYGPCH-UHFFFAOYSA-L manganese(2+);naphthalene-2-carboxylate Chemical compound [Mn+2].C1=CC=CC2=CC(C(=O)[O-])=CC=C21.C1=CC=CC2=CC(C(=O)[O-])=CC=C21 SGGOJYZMTYGPCH-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- GEMHFKXPOCTAIP-UHFFFAOYSA-N n,n-dimethyl-n'-phenylcarbamimidoyl chloride Chemical compound CN(C)C(Cl)=NC1=CC=CC=C1 GEMHFKXPOCTAIP-UHFFFAOYSA-N 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 238000002834 transmittance 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)
Description
本発明はテレフタル酸の製造方法に関するもの
であり、詳しくは、直接、グリコール成分と反応
させてポリエステルを製造することのできる高純
度テレフタル酸の製造方法に関するものである。
テレフタル酸はポリエスエルの原料として有用
であり、通常、パラキシレンを酢酸溶媒中、重金
属及び臭素を含有する触媒の存在下、分子状酸素
と反応させる所謂、SD法により製造されている。
しかしながら、通増、SD法により製造されるテ
レフタル酸中には、1000〜3000ppmの４−カルボ
キシベンズアルデヒド（以下、4CBAと略称す
る）が不純物として含有されているため、そのま
ま、例えば、繊維用、フイルム用などのポリエス
テル原料として使用することはできない。
そのため、従来、テレフタル酸をメタノールと
反応させてジメチルテレフタレートとし精製した
のち、グリコール成分と反応させるか、又は、テ
レフタル酸を高温、高圧下で水溶媒中に溶解し、
例えば、パラジウムなどの貴金属触媒と接触させ
て精製したのち、ポリエステル原料とする方法が
採られてきた。
しかしながら、これらの方法はいずれも、SD
法による粗テレフタル酸の製造プラントの他に、
精製用の別のプラントを必要とする問題があつ
た。そこで、近年、パラキシレンの酸化を行なう
に際し、特定の触媒、酸化条件、又は酸化方式を
採用することにより、１つのプラントで直接、高
純度テレフタル酸を製造できるようになつた。
本出願人は先に、１つのプラントで直接、
4CBA含有量が500ppm以下の高純度テレフタル
酸を工業的有利に製造するための方法として、パ
ラキシレンを酸化して得たテレフタル酸を含有す
る混合物を、引き続き、酸化反応温度よりも定温
で追酸化したのち、235℃以上の高温で再追酸化
する方法を提案した。（特開昭55−55138号）この
方法は１つのプラントで高純度テレフタル酸が得
られるのは勿論のこと、テレフタル酸の製造中に
起る酢酸溶媒の燃焼損失が少ないので、工業的に
有利な方法である。
しかしながら、この方法では再追酸化を高温で
行なうため、この工程において、あまり多量の分
子状酸素を供給すると、酢酸溶媒の燃焼が増大す
る傾向がある。そのため、再追酸化においては、
追酸化混合物中の被酸化物の含有量、製品テレフ
タル酸の所望品質などを考慮して所定量の分子状
酸素が用いられる。ところが、分子状酸素の供給
量があまり少ない場合には、酸化力が弱くなり十
分な再追酸化の効果が得られない。この酸化力を
補うためには、例えば、処理温度を高めれば改善
されるが、エネルギーコストが高くなり工業的に
は有利な方法ではない。
本発明者等は上記実情に鑑み、高温での再追酸
化を比較的低温においても、少量の分子状酸素に
より効果的に再追酸化できる方法につき種種検討
した結果、第１の酸化反応が終了した以降に、触
媒成分を添加することにより、高温での再追酸化
が良好に行なわれることを見い出し本発明を完成
した。
すなわち、本発明の要旨は、「パラキシレンを
酢酸溶媒中、重金属及び臭素よりなる触媒の存在
下、180〜230℃の温度において分子状酸素により
パラキシレンの95重量％以上をテレフタル酸に酸
化して得た第１酸化反応の混合物を、第１酸化反
応の温度より低い温度にて分子増酸素により追酸
化し、次いで、第１酸化反応の温度よりも高い温
度にて分子状酸素により再追酸化したのち、反応
混合物を層析し、更に固液分離するテレフタル酸
の連続的製造法において、第１酸化反応の終了後
から再追酸化処理の間に、第１酸化反応を用いた
重金属又は臭素に対して、各々0.05〜２媒量の重
金属又は臭素を添加することを特徴とする高純度
テレフタル酸の製造法」に存する。
以下、本発明を詳細に説明する。
本発明では対象となるテレフタル酸の製造法と
しては、パラキシレンを酢酸溶媒中、重金属と臭
素を含有する触媒の存在下、分子状酸素と反応さ
せる方法が挙げられる。
本発明では、先ず、通増、撹拌槽型の第１反応
器でパラキシレンの95重量％以上、好ましくは98
重量％以上をテレフタル酸に酸化するが、通常そ
の反応温度は180〜230℃、好ましくは190〜210℃
であり、圧力は数Kg／cm2〜100Kg／cm2、好ましく
は10〜30Kg／cm2である。反応温度があまり低いと
パラキシレンを十分に酸化することができず、逆
に、あまり高すぎると高純度のテレフタル酸が得
られないばかりか、酢酸溶媒の燃焼損失が増大す
るので好ましくない。また、第１反応器での反応
時間はパラキシレンの95重量％以上がテレフタル
酸に酸化できる時間が必要であり、通常、30〜
200分、好ましくは40〜150分程度である。
本発明で使用する触媒は通常、コバルト−マン
ガン−臭素の三元素を含むものであり、例えば、
溶媒に対してコバルト金属として120〜600ppm、
好ましくは150〜400ppmのコバルト化合物、コバ
ルトに対してマンガン金属として0.5〜1.5倍のマ
ンガン化合物及び溶媒に対して臭素として500〜
2000ppm、好ましくは600〜1500ppmの臭素化合
物が使用される。これらの化合物の具体例として
は、酢酸コバルト、ナフテン酸コバルトなどのコ
バルト化合物、酢酸マンガン、ナフテン酸マンガ
ンなどのマンガン化合物及び臭化水素、臭化ナト
リウム、臭化コバルト、臭化マンガンなどの臭素
化合物が挙げられる。なお、臭化マンガン、臭化
コバルトを使用した場合には、二種の触媒成分を
兼ねることもできる。
第１反応器に供給するパラキシレンと溶媒との
割合は通常、パラキシレンに対して２〜６重量倍
であり、溶倍があまり少ない場合には、反応器内
の撹拌が良好に行なわれず、更に、後述する高温
の再追酸化が良好に行なわれていにので好ましく
ない。また、酢酸溶媒中には例えば、20重量％以
下の水を含有していてもよい。第１反応器の液相
中に供給する分子状酸素は通常空気でよく、パラ
キシレンに対し分子状酸素として３〜100モル倍
の割合であり、通常、酸化排ガス中の酸素濃度が
1.5〜８容量％となるように供給される。
上述の第１酸化反応では反応器からの凝縮性ガ
スを冷却して得た凝縮液の一部を反応器に還流す
ることなく系外に抜き出すことによつて、反応器
内の水分濃度を例えば、５〜15重量％と低濃度に
調節してもよい。
また、本発明では第１反応器における温度、圧
力、滞留時間及び触媒組成などを調節することに
より、反応母液中の4CBA濃度を1000〜3000ppm
に保持するのが好ましい。この反応母液中の
4CBA濃度は低いほど高純度のテレフタル酸が得
られるが、一方、そのような条件下で酸化反応を
行なう場合は酢酸溶媒の燃焼は増大する方向にあ
る。しかし、本発明においては、この反応母液中
の4CBA濃度をある程度高く保持しても、後述の
追酸化及び再追酸化処理により、高純度のテレフ
タル酸を最終的に得ることができるので、第１反
応器での酢酸溶媒の燃焼を著しく抑制することが
できる。
次に、第１反応器で得られたテレフタル酸を含
有するスラリーは、たとえば撹拌槽型を第２反応
器に供給し、通常、パラキシレンを供給すること
なく、第１反応器の反応温度よりも０〜50℃、好
ましくは２〜30℃低い温度で分子状酸素により追
酸化処理を行なう。この処理により、主に、母液
中の酸化中間体が酸化されるが、この温度があま
り低い場合には、反応スラリー中に含有される酸
化中間体を十分に酸化することができず、一方、
第１反応器の反応温度よりも高温の場合には、製
品テレフタル酸の着色成分となる不純物が生成す
るので好ましくない。また、この追酸化処理の時
間は通常、20〜90分、好ましくは30〜60分であ
る。
この追酸化で使用する分子状酸素は、反応混合
物中に含まれる被酸化物が少量であるので、その
供給量は第１反応器への供給量の1/10〜1/1000程
度であり、通常、酸化排ガス中の酸素濃度が１〜
６容量％となる量が好ましい。分子状酸素として
は通常、空気又は不活性ガスで希釈した空気を用
いればよい。
上述の追酸化を終えた反応混合物は次いで、別
の撹拌槽型の反応器に供給し、通常、パラキシレ
ンを供給することなく、第１酸化反応の温度より
も高い温度にて分子状酸素により再追酸化処理を
行なう。この処理によりテレフタル酸粒子中の酸
化中間体が母液中に抽出され、そして、酸化され
る。この際の処理温度はあまり低いとテレフタル
酸粒子中の酸化中間体が良好に抽出されず、ま
た、あまり高いとエネルギー的に経済的でないば
かりか、着色不純物が生成する恐れがあり、通
常、230℃以上、好ましくは235〜290℃である。
反応圧力は混合物を液相に保持することができる
圧力が必要であり、通常、工業的には30〜100
Kg／cm2である。また、滞留時間は５〜120分、好
ましくは10〜60分である。
この再追酸化の工程では被酸化物が極めて少量
であり、しかも、高温であるため、分子状酸素の
供給量をあまり多くすると、酢酸溶媒の燃焼が増
大するので、通常、分子状酸素の供給量は混合物
中のテレフタル酸に対して、0.003〜0.3モル倍、
好ましくは0.01〜0.1モル倍であり、また、酸化
排ガス中の酸素濃度が通常、0.5容量％以下とな
るようにするのが好ましい。ここで用いる分子状
酸素としては、通常、空気又は不活性ガスで希釈
した空気が挙げられる。
上述のように本発明ではパラキシレンの95重量
％以上をテレフタル酸に酸化して得た混合物を低
温で追酸化したのち、次いで、高温で最追酸化す
るものであるが、各処理で用いられる反応器は通
常、上部に還流冷却器を有する撹拌槽タイプのも
のである。各工程における反応段数は通常、それ
ぞれ１段であるが、必要に応じて、追酸化工程又
は最追酸化工程を複数段としてもよい。また、追
酸化後の混合物は引き続き、最追酸化を行なうた
めに、通常、混合物をポンプにより高圧部に圧入
し、所定温度に加熱するが、この加熱処理は例え
ば、モノチユーブ型又はマルチチユーブ型のチユ
ーブ型熱交換器により行なうことができる。
本発明においては、第１酸化反応の終了後から
再追酸化処理までの間に、重金属及び／又は臭素
を添加することを必須の要件とするものである。
この触媒成分の追加的な添加により、高温での再
追酸化工程における酸化力が著しく向上し、その
ため、極く少量の分子状酸素によつても効率的な
酸化が行なわれるのである。
本発明においては、上記のように触媒成分を追
加的に添加することが重要であつて、あらかじめ
第１酸化反応における触媒使用量を増加させてお
いても、本発明で期待する効果は得られない。
触媒成分を添加する時点としては、通常、第１
酸化反応の終了後、低温追酸化処理工程までの間
がよい。この場合、添加された触媒成分は継続的
に作用するので再追酸化のみならず、追酸化の内
容も改善されるので好ましい。また、添加する触
媒成分の量は通常、第１酸化反応で用いた重金属
又は臭素に対いて、各々0.05〜２倍、好ましくは
0.1〜１倍である。この触媒成分の量があまり少
ない場合には、本発明で期待する効果は得られ
ず、逆に、あまり多くても効果に差異はないので
経済的でない。追加する触媒成分としては、重金
属単独、あるいは臭素単独でもよいが重金属と臭
素の両者を添加するのが好ましい。特に、第１酸
化反応で用いた触媒組成とほぼ同様なものを添加
するのが好ましい。
高温での再追酸化を終えた反応混合物は、常法
に従つて晶析される。晶析処理は通常、多段で行
ない徐々に温度、圧力を下げて行くのが好まし
い。次に、例えば、遠心分離などの固液分離を行
ない、テレフタル酸の結晶を回収することができ
る。テレフタル酸の結晶は必要に応じて、例え
ば、水又は酢酸などにて洗浄したのち乾燥処理さ
れ製品となる。一方、反応母液は通常、蒸溜塔に
送られ生成水、触媒、副生物を除去し酢酸を回収
する。また、本発明では反応母液中の副生物、特
に、酸化反応を妨害する不純物が極めて少ないの
で、反応母液の10〜80重量％をそのまま第１反応
器へリサイクルすることもできる。
以上、本発明によれば、4CBA含有量が
500ppm以下の高純度テレフタル酸を１つのプラ
ントにおいて製造する際、より高純度のテレフタ
ル酸が容易に製造できるので、工業的且つ経済的
に極めて有利なものである。
次に、本発明を実施例により更に詳細に説明す
るが、本発明はその要旨を越えない限り以下の実
施例に限定されるものではない。
なお、実施例中、「部」とあるのは「重量部」
を表わす。
実施例 １
第１図のフローシートに示す反応装置を用いて
反応を行なつた。
還流冷却装置、撹拌装置、原料及び溶媒送入
口、空気導入口及び反応スラリー抜出口を備えた
耐圧チタン製の第１反応器１に、パイプ７よりパ
ラシレン１部／時、水５％を含む酢酸4.5部／時
と酢酸コバルト・４水和物0.0025部／時、酢酸マ
ンガン・４水和物0.0027部／時及び４７％臭化水
素酸0.0039部／時よりなる混合物を供給し、温度
200℃、圧力18Kg／cm2Ｇ、滞留時間90分の条件下、
酸化ガスとして空気を用い、酸化反応の排ガス中
の酸素濃度が４容量％となるようにパイプ１０よ
り供給し、パイプ８より還流液1.5部／時を抜き
出し反応器１中の水分濃度を約10重量％にコント
ロールし、パラキシレンの液相酸化反応を行なつ
た。
第１反応器１からの混合物はパイプ１３を通り
第１反応器１と同じ装備の第２反応器２に連続的
に供給した。なお、この際に、第１反応器に供給
した触媒に対して、0.25倍に相当する全く同じ組
成の触媒をパイプ９よりパイプ１３中に添加し
た。
第２反応器２では温度185℃、圧力11Kg／cm2Ｇ、
滞留時間30分の条件下で、パイプ１１から酸化反
応の排ガス中の酸素濃度が４容量％となるよう
に、空気を供給し、追酸化を行なつた。
第２反応器２からの混合物はパイプ１４を通
り、昇圧ポンプ（図示せず）により圧力55Kg／cm2
Ｇに昇圧し更に、モノチユーブ型加熱器３に供給
し、混合物の温度を260℃まで昇温した。
更に、加熱器３を出た混合物は次いで、第１反
応器１と同じ装備を持つ第３反応器４に供給し
た。第３反応器４では温度260℃、圧力55Kg／cm2
Ｇ、滞留時間30分の条件下で、空気0.07部／時を
パイプ１２より供給し再追酸化を行なつた。
このように順次、追酸化および再追酸化を行な
つたのち、混合物を晶析器５にて冷却晶析し、次
いで、遠心分離機６で混合物を過してテレフタ
ル酸の結晶を回収した。
上述のようにして得たテレフタル酸につき、
4CBA含有量及び透過率T340を測定し第１表に示
す結果を得た。
比較例 １
実施例１の方法において、パイプ９からの触媒
の供給を行なうことなく、全く同様な方法でテレ
フタル酸の製造を行つた場合の結果を第１表に示
す。
比較例 ２
実施例１の方法において、パイプ９からの触媒
の供給を中止し、これに相当する量の触媒を第１
反応器に最初から供給し、第２反応器の出口にお
けるテレフタル酸中の4CBAレベルを実施例１と
同じとなるように第１反応器の温度及び圧力を調
節して酸化反応を行なつた以外は同様な方法でテ
レフタル酸の製造を行なつた場合の結果を第１表
に示す。
The present invention relates to a method for producing terephthalic acid, and more particularly, to a method for producing high-purity terephthalic acid that can produce polyester by directly reacting with a glycol component. Terephthalic acid is useful as a raw material for polyester, and is usually produced by the so-called SD method in which paraxylene is reacted with molecular oxygen in an acetic acid solvent in the presence of a catalyst containing heavy metals and bromine.
However, since terephthalic acid produced by the SD method contains 1000 to 3000 ppm of 4-carboxybenzaldehyde (hereinafter abbreviated as 4CBA) as an impurity, it can be used as it is, for example, for textiles and films. It cannot be used as a raw material for polyester. Therefore, conventionally, terephthalic acid is reacted with methanol to purify dimethyl terephthalate and then reacted with a glycol component, or terephthalic acid is dissolved in an aqueous solvent under high temperature and pressure.
For example, a method has been adopted in which the material is purified by contacting with a noble metal catalyst such as palladium, and then used as a raw material for polyester. However, all of these methods
In addition to the crude terephthalic acid production plant by
There was a problem that required a separate plant for purification. Therefore, in recent years, it has become possible to directly produce high-purity terephthalic acid in one plant by employing specific catalysts, oxidation conditions, or oxidation methods when oxidizing paraxylene. The applicant previously proposed that directly in one plant,
As an industrially advantageous method for producing high-purity terephthalic acid with a 4CBA content of 500 ppm or less, a mixture containing terephthalic acid obtained by oxidizing paraxylene is subsequently additionally oxidized at a constant temperature below the oxidation reaction temperature. After that, we proposed a method of re-oxidizing at a high temperature of 235℃ or higher. (Japanese Patent Application Laid-Open No. 55-55138) This method is industrially advantageous because not only can high-purity terephthalic acid be obtained in one plant, but the combustion loss of the acetic acid solvent that occurs during the production of terephthalic acid is small. This is a great method. However, in this method, re-oxidation is carried out at a high temperature, so if too much molecular oxygen is supplied in this step, combustion of the acetic acid solvent tends to increase. Therefore, in reoxidation,
A predetermined amount of molecular oxygen is used in consideration of the content of the substance to be oxidized in the additional oxidation mixture, the desired quality of the product terephthalic acid, etc. However, if the amount of molecular oxygen supplied is too small, the oxidizing power becomes weak and a sufficient re-oxidation effect cannot be obtained. This oxidizing power can be compensated for by, for example, increasing the treatment temperature, but this is not an industrially advantageous method as it increases the energy cost. In view of the above-mentioned circumstances, the present inventors investigated various methods for effectively re-oxidizing with a small amount of molecular oxygen even at relatively low temperatures, and found that the first oxidation reaction was completed. The present invention was completed based on the discovery that re-oxidation at high temperatures can be carried out well by adding a catalyst component after the oxidation process. That is, the gist of the present invention is to oxidize para-xylene to terephthalic acid in an acetic acid solvent in the presence of a catalyst consisting of heavy metals and bromine with molecular oxygen at a temperature of 180 to 230° C. The first oxidation reaction mixture obtained by In a continuous production method for terephthalic acid in which the reaction mixture is layered after oxidation and then solid-liquid separated, heavy metals or A method for producing high-purity terephthalic acid, which comprises adding heavy metals or bromine in an amount of 0.05 to 2, respectively, to bromine. The present invention will be explained in detail below. The method for producing terephthalic acid that is the object of the present invention includes a method in which paraxylene is reacted with molecular oxygen in an acetic acid solvent in the presence of a catalyst containing a heavy metal and bromine. In the present invention, firstly, in a first reactor of a stirred tank type, para-xylene is contained in an amount of 95% by weight or more, preferably 98% by weight.
More than % by weight is oxidized to terephthalic acid, and the reaction temperature is usually 180-230℃, preferably 190-210℃
The pressure is several kg/cm 2 to 100 kg/cm 2 , preferably 10 to 30 kg/cm 2 . If the reaction temperature is too low, paraxylene cannot be sufficiently oxidized, and on the other hand, if the reaction temperature is too high, not only will high purity terephthalic acid not be obtained, but the combustion loss of the acetic acid solvent will increase, which is not preferred. In addition, the reaction time in the first reactor is required to allow at least 95% by weight of paraxylene to be oxidized to terephthalic acid.
It is about 200 minutes, preferably about 40 to 150 minutes. The catalyst used in the present invention usually contains three elements: cobalt, manganese, and bromine, for example,
120-600ppm as cobalt metal relative to solvent,
Preferably 150 to 400 ppm of cobalt compound, 0.5 to 1.5 times of manganese compound as manganese metal to cobalt, and 500 to 500 ppm of bromine to solvent.
2000 ppm, preferably 600 to 1500 ppm of bromine compounds are used. Specific examples of these compounds include cobalt compounds such as cobalt acetate and cobalt naphthenate, manganese compounds such as manganese acetate and manganese naphthenate, and bromine compounds such as hydrogen bromide, sodium bromide, cobalt bromide, and manganese bromide. can be mentioned. Note that when manganese bromide and cobalt bromide are used, they can also serve as two types of catalyst components. The ratio of paraxylene and solvent supplied to the first reactor is usually 2 to 6 times the weight of paraxylene, and if the ratio is too small, stirring in the reactor will not be carried out well. Furthermore, high temperature reoxidation, which will be described later, is not carried out satisfactorily, which is not preferable. Further, the acetic acid solvent may contain, for example, 20% by weight or less of water. The molecular oxygen supplied to the liquid phase of the first reactor may normally be air, with a ratio of 3 to 100 moles of molecular oxygen to paraxylene, and the oxygen concentration in the oxidation exhaust gas is usually
It is supplied at a concentration of 1.5 to 8% by volume. In the above-mentioned first oxidation reaction, a part of the condensate obtained by cooling the condensable gas from the reactor is extracted from the system without being refluxed to the reactor, thereby reducing the water concentration in the reactor, for example. , the concentration may be adjusted to as low as 5 to 15% by weight. In addition, in the present invention, the 4CBA concentration in the reaction mother liquor can be adjusted to 1000 to 3000 ppm by adjusting the temperature, pressure, residence time, catalyst composition, etc. in the first reactor.
It is preferable to keep it at In this reaction mother liquor
The lower the 4CBA concentration, the more pure terephthalic acid can be obtained, but on the other hand, when the oxidation reaction is carried out under such conditions, the combustion of the acetic acid solvent tends to increase. However, in the present invention, even if the 4CBA concentration in this reaction mother liquor is kept high to some extent, high-purity terephthalic acid can be finally obtained through the additional oxidation and re-additional oxidation treatments described below. Combustion of acetic acid solvent in the reactor can be significantly suppressed. Next, the slurry containing terephthalic acid obtained in the first reactor is fed to a second reactor, for example in a stirred tank type, and the slurry is then fed to a second reactor, usually at a temperature lower than the reaction temperature of the first reactor, without feeding para-xylene. Additional oxidation treatment is carried out using molecular oxygen at a temperature lower than 0 to 50°C, preferably 2 to 30°C. This treatment mainly oxidizes the oxidized intermediates in the mother liquor, but if this temperature is too low, the oxidized intermediates contained in the reaction slurry cannot be sufficiently oxidized;
If the temperature is higher than the reaction temperature of the first reactor, impurities that become coloring components of the product terephthalic acid will be produced, which is not preferable. Further, the time for this additional oxidation treatment is usually 20 to 90 minutes, preferably 30 to 60 minutes. The amount of molecular oxygen used in this additional oxidation is approximately 1/10 to 1/1000 of the amount supplied to the first reactor, since the oxidized substance contained in the reaction mixture is small. Usually, the oxygen concentration in the oxidizing exhaust gas is 1~
An amount of 6% by volume is preferred. Generally, air or air diluted with an inert gas may be used as molecular oxygen. The reaction mixture that has undergone the additional oxidation described above is then fed to another stirred tank reactor and treated with molecular oxygen at a temperature higher than that of the first oxidation reaction, usually without feeding paraxylene. Perform reoxidation treatment. This treatment extracts the oxidized intermediates in the terephthalic acid particles into the mother liquor and oxidizes them. If the treatment temperature at this time is too low, the oxidized intermediates in the terephthalic acid particles will not be extracted well, and if the treatment temperature is too high, it will not only be energy-economical but also cause colored impurities to be produced. ℃ or higher, preferably 235 to 290℃.
The reaction pressure must be able to maintain the mixture in the liquid phase, and is usually industrially 30 to 100
Kg/ cm2 . Further, the residence time is 5 to 120 minutes, preferably 10 to 60 minutes. In this re-oxidation process, the amount of oxidized substances is extremely small and the temperature is high. The amount is 0.003 to 0.3 times the terephthalic acid in the mixture,
It is preferably 0.01 to 0.1 mole times, and it is preferable that the oxygen concentration in the oxidizing exhaust gas is usually 0.5% by volume or less. The molecular oxygen used here usually includes air or air diluted with an inert gas. As mentioned above, in the present invention, a mixture obtained by oxidizing 95% by weight or more of paraxylene to terephthalic acid is additionally oxidized at a low temperature, and then additionally oxidized at a high temperature. The reactor is usually of the stirred tank type with a reflux condenser at the top. The number of reaction stages in each step is usually one, but if necessary, the additional oxidation step or the additional oxidation step may be performed in multiple stages. Furthermore, in order to perform further oxidation on the mixture after additional oxidation, the mixture is usually pumped into a high-pressure section and heated to a predetermined temperature. This can be done using a tube heat exchanger. In the present invention, it is essential to add heavy metals and/or bromine between the end of the first oxidation reaction and the re-oxidation treatment.
The additional addition of this catalyst component significantly improves the oxidizing power in the re-oxidation step at high temperatures, so that efficient oxidation can be carried out even with a very small amount of molecular oxygen. In the present invention, it is important to additionally add a catalyst component as described above, and even if the amount of catalyst used in the first oxidation reaction is increased in advance, the expected effects of the present invention cannot be obtained. do not have. The point at which the catalyst component is added is usually the first
The period after the completion of the oxidation reaction and before the low-temperature additional oxidation treatment step is preferable. In this case, since the added catalyst component acts continuously, not only the re-oxidation but also the content of the additional oxidation is improved, which is preferable. Further, the amount of the catalyst component to be added is usually 0.05 to 2 times, preferably 0.05 to 2 times, each of the heavy metal or bromine used in the first oxidation reaction.
It is 0.1 to 1 times. If the amount of this catalyst component is too small, the expected effects of the present invention cannot be obtained; on the other hand, even if the amount is too large, there is no difference in the effect and it is not economical. The additional catalyst component may be a heavy metal alone or bromine alone, but it is preferable to add both a heavy metal and bromine. In particular, it is preferable to add a catalyst having substantially the same composition as that used in the first oxidation reaction. The reaction mixture that has been reoxidized at high temperature is crystallized in a conventional manner. It is usually preferable to carry out the crystallization treatment in multiple stages and gradually lower the temperature and pressure. Next, for example, solid-liquid separation such as centrifugation can be performed to recover crystals of terephthalic acid. If necessary, the terephthalic acid crystals are washed with water or acetic acid, and then dried to become a product. On the other hand, the reaction mother liquor is usually sent to a distillation column to remove produced water, catalyst, and byproducts, and recover acetic acid. Furthermore, in the present invention, by-products in the reaction mother liquor, especially impurities that interfere with the oxidation reaction, are extremely small, so that 10 to 80% by weight of the reaction mother liquor can be recycled as is to the first reactor. As described above, according to the present invention, the 4CBA content is
When producing high purity terephthalic acid of 500 ppm or less in one plant, it is extremely advantageous industrially and economically since higher purity terephthalic acid can be easily produced. Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded. In addition, in the examples, "part" means "part by weight"
represents. Example 1 A reaction was carried out using the reaction apparatus shown in the flow sheet of FIG. A pressure-resistant titanium first reactor 1 equipped with a reflux cooling device, a stirring device, a raw material and solvent inlet, an air inlet, and a reaction slurry outlet is supplied with 1 part/hour of parasylene and acetic acid containing 5% water from a pipe 7. A mixture consisting of 4.5 parts/hour, cobalt acetate tetrahydrate 0.0025 parts/hour, manganese acetate tetrahydrate 0.0027 parts/hour and 47% hydrobromic acid 0.0039 parts/hour was fed, and the temperature
Under the conditions of 200℃, pressure 18Kg/cm 2 G, residence time 90 minutes,
Air is used as the oxidizing gas, and is supplied through pipe 10 so that the oxygen concentration in the exhaust gas of the oxidation reaction is 4% by volume, and 1.5 parts/hour of reflux liquid is extracted from pipe 8 to reduce the water concentration in reactor 1 to approximately 10%. A liquid phase oxidation reaction of para-xylene was carried out by controlling the weight %. The mixture from the first reactor 1 was continuously fed through a pipe 13 to a second reactor 2 equipped with the same equipment as the first reactor 1. At this time, a catalyst having exactly the same composition as the catalyst supplied to the first reactor was added into the pipe 13 from the pipe 9 in an amount equivalent to 0.25 times. In the second reactor 2, the temperature was 185℃, the pressure was 11Kg/cm 2 G,
Under conditions of a residence time of 30 minutes, additional oxidation was performed by supplying air from the pipe 11 so that the oxygen concentration in the exhaust gas from the oxidation reaction was 4% by volume. The mixture from the second reactor 2 passes through a pipe 14 and is pumped to a pressure of 55 Kg/cm 2 by a booster pump (not shown).
The pressure of the mixture was increased to 260°C, and the mixture was further supplied to a monotube heater 3 to raise the temperature of the mixture to 260°C. Furthermore, the mixture leaving the heater 3 was then fed to a third reactor 4 with the same equipment as the first reactor 1. In the third reactor 4, the temperature is 260℃ and the pressure is 55Kg/cm 2
G. Under conditions of a residence time of 30 minutes, 0.07 parts/hour of air was supplied from pipe 12 to carry out re-oxidation. After sequentially performing additional oxidation and re-oxidation in this manner, the mixture was cooled and crystallized in a crystallizer 5, and then passed through a centrifuge 6 to recover crystals of terephthalic acid. For the terephthalic acid obtained as described above,
The 4CBA content and transmittance T 340 were measured and the results shown in Table 1 were obtained. Comparative Example 1 Table 1 shows the results when terephthalic acid was produced in exactly the same manner as in Example 1 without supplying the catalyst from pipe 9. Comparative Example 2 In the method of Example 1, the supply of catalyst from pipe 9 was stopped, and a corresponding amount of catalyst was added to the first pipe.
The oxidation reaction was carried out by supplying 4CBA to the reactor from the beginning and adjusting the temperature and pressure of the first reactor so that the level of 4CBA in terephthalic acid at the outlet of the second reactor was the same as in Example 1. Table 1 shows the results when terephthalic acid was produced in a similar manner.
【表】
(注) 触媒量は溶媒に対する原子としての
重量割合
[Table] (Note) The amount of catalyst is the weight ratio of atoms to the solvent.
第１図は本発明の実施例で使用した反応装置を
示すフローシートであり、１は第１反応器、２は
第２反応器、３は加熱器、４は第３反応器、５は
晶析器を示す。
FIG. 1 is a flow sheet showing the reactor used in the examples of the present invention, 1 is the first reactor, 2 is the second reactor, 3 is the heater, 4 is the third reactor, and 5 is the crystallizer. The analyzer is shown.
Claims (1)
よりなる触媒の存在下、180〜230℃の温度におい
て分子状酸素によりパラキシレンの95重量％以上
をテレフタル酸に酸化して得た第１酸化反応の混
合物を、第１酸化反応の温度より低い温度にて分
子状酸素により追酸化し、次いで、第１酸化反応
の温度よりも高い温度にて分子状酸素により再追
酸化したのち、反応混合物を晶析し、更に、固液
分離するテレフタル酸の連続的製造法において、
第１酸化反応の終了後から再追酸化処理の間に、
第１酸化反応で用いた重金属又は臭素に対して、
各々0.05〜２倍量の重金属又は臭素を添加するこ
とを特徴とする高純度テレフタル酸の製造法。1. The first oxidation reaction obtained by oxidizing para-xylene to terephthalic acid in an acetic acid solvent at a temperature of 180 to 230°C at a temperature of 95% or more of para-xylene to terephthalic acid. The mixture is additionally oxidized with molecular oxygen at a temperature lower than the temperature of the first oxidation reaction, then re-oxidized with molecular oxygen at a temperature higher than the temperature of the first oxidation reaction, and then the reaction mixture is crystallized. In the continuous production method of terephthalic acid, which involves separation and solid-liquid separation,
After the completion of the first oxidation reaction and during the re-oxidation treatment,
For the heavy metal or bromine used in the first oxidation reaction,
A method for producing high-purity terephthalic acid, which comprises adding heavy metals or bromine in an amount of 0.05 to 2 times each.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57200582A JPS5993029A (en) | 1982-11-16 | 1982-11-16 | Production of high-purity terephthalic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57200582A JPS5993029A (en) | 1982-11-16 | 1982-11-16 | Production of high-purity terephthalic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5993029A JPS5993029A (en) | 1984-05-29 |
| JPH0357887B2 true JPH0357887B2 (en) | 1991-09-03 |
Family
ID=16426732
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP57200582A Granted JPS5993029A (en) | 1982-11-16 | 1982-11-16 | Production of high-purity terephthalic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5993029A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7615663B2 (en) | 2004-09-02 | 2009-11-10 | Eastman Chemical Company | Optimized production of aromatic dicarboxylic acids |
-
1982
- 1982-11-16 JP JP57200582A patent/JPS5993029A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5993029A (en) | 1984-05-29 |
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