JPH0579657B2 - - Google Patents
Info
- Publication number
- JPH0579657B2 JPH0579657B2 JP10037385A JP10037385A JPH0579657B2 JP H0579657 B2 JPH0579657 B2 JP H0579657B2 JP 10037385 A JP10037385 A JP 10037385A JP 10037385 A JP10037385 A JP 10037385A JP H0579657 B2 JPH0579657 B2 JP H0579657B2
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- nitric acid
- reaction
- thermal decomposition
- decomposition
- 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
- 239000007789 gas Substances 0.000 claims description 71
- 238000006243 chemical reaction Methods 0.000 claims description 37
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 33
- 229910017604 nitric acid Inorganic materials 0.000 claims description 33
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 20
- 230000001590 oxidative effect Effects 0.000 claims description 19
- 238000001125 extrusion Methods 0.000 claims description 12
- OFOBLEOULBTSOW-UHFFFAOYSA-N Malonic acid Chemical compound OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- 239000002994 raw material Substances 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 230000003197 catalytic effect Effects 0.000 claims description 3
- GQPLMRYTRLFLPF-UHFFFAOYSA-N Nitrous Oxide Chemical compound [O-][N+]#N GQPLMRYTRLFLPF-UHFFFAOYSA-N 0.000 claims 8
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims 6
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 claims 3
- JCXJVPUVTGWSNB-UHFFFAOYSA-N nitrogen dioxide Inorganic materials O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 claims 3
- 239000001272 nitrous oxide Substances 0.000 claims 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims 2
- ODUCDPQEXGNKDN-UHFFFAOYSA-N Nitrogen oxide(NO) Natural products O=N ODUCDPQEXGNKDN-UHFFFAOYSA-N 0.000 claims 2
- 238000000354 decomposition reaction Methods 0.000 description 19
- 238000000034 method Methods 0.000 description 12
- WNLRTRBMVRJNCN-UHFFFAOYSA-N adipic acid Chemical compound OC(=O)CCCCC(O)=O WNLRTRBMVRJNCN-UHFFFAOYSA-N 0.000 description 10
- 238000010521 absorption reaction Methods 0.000 description 8
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 8
- 238000004523 catalytic cracking Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 235000011037 adipic acid Nutrition 0.000 description 5
- 239000001361 adipic acid Substances 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 239000003054 catalyst Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- HPXRVTGHNJAIIH-UHFFFAOYSA-N cyclohexanol Chemical compound OC1CCCCC1 HPXRVTGHNJAIIH-UHFFFAOYSA-N 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 150000001991 dicarboxylic acids Chemical class 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- 230000002452 interceptive effect Effects 0.000 description 2
- 230000003444 anaesthetic effect Effects 0.000 description 1
- 239000003994 anesthetic gas Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- -1 consists of N 2 Chemical compound 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000002425 crystallisation Methods 0.000 description 1
- 230000008025 crystallization Effects 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/20—Nitrogen oxides; Oxyacids of nitrogen; Salts thereof
- C01B21/24—Nitric oxide (NO)
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Description
（産業上の利用分野）
本発明は、硝酸を使用してシクロアルカノール
および／またはシクロアルカノンを酸化してジカ
ルボン酸を製造するに際し、副生するN2Ｏを含
む排ガスを処理して、このまゝでは利用価値のな
い、該排ガス中のN2Ｏを効率的に有価な硝酸に
転換し、再利用することによつて、製造コストが
低減できる有利なジカルボン酸製造法に関する。
（従来の技術）
硝酸を使用してシクロアルカノールおよび／ま
たはシクロアルカノンを酸化してジカルボン酸を
製造するに際し、副生するガスは、一般に、N2
Ｏ，NO，NO2，O2，CO2，H2Ｏ，HNO3，N2
からなる。このうち、NOおよびNO2は空気酸化
の後、水による吸収反応によつて、硝酸として回
収するが、N2Ｏはこのままでは回収できないた
め、接触分解によつて、N2とO2に分解した後、
その他の排ガスとともに大気に放棄している。
ジカルボン酸の製造時に発生する排ガスとは直
接関係ないが、N2Ｏを含む排ガスの接触分解に
よる処理方法に関しては、公知技術は多数あり、
最近では米国特許4259303（′81）等がある。これ
によると、廃麻酔ガス中のN2Ｏの処理に際し、
NiO，Fe2O3等を触媒に利用し、反応温度350〜
550℃、滞留時間４〜９秒で接触分解反応を行な
わせると、N2Ｏはほゞ100％N2とO2に分解でき
る。
しかしながら、これらの接触分解技術では、
N2Ｏを含む排ガスをN2とO2に無害化処理するに
とゞまり、N2Ｏの有効利用には値しない。
一方、N2Ｏは無触媒で熱分解反応を行なわせ
ると、
(1) N2Ｏ→N2＋１／２O2
(2) N2Ｏ→NO＋１／２N2
の並発反応になることはよく知られており、NO
から硝酸を回収することが検討された。エフ・ジ
エイ・リンダース（F.J.LINDARS）らプロシー
デイング・オブ・ザ・ロイヤル・ソサイアテイ
（ロンドン）〔Proc.Roy.Soc.（London）〕A231，
162，（′55）によると、反応温度720℃、滞留時間
1830秒で、N2Ｏ→NO＋１／２N2の分解反応が約５
％進むと報告している。
（発明が解決しようとする問題点）
従来技術記載の方法で、N2Ｏを含む排ガスを
接触分解によつて処理することは、N2Ｏを価値
のないN2，O2に分解することになり、N2Ｏの有
効利用という目的を満足しない。
一方、N2ＯをNOに転換し、これから硝酸を得
ることが可能な無触媒、熱分解反応に関する過去
の技術は、NO収率が低く、経済的にも問題が多
い。
また、本発明者らによれば、従来技術は、シク
ロアルカノールおよび／またはシクロアルカノン
の硝酸酸化によつてジカルボン酸を製造する際に
副生するN2Ｏを含む酸化排ガス（以下、単に
「該酸化排ガス」と云う）のような場合には、多
量の共存ガス（NO，NO2，CO2，HNO3，O2，
N2）を含むため適用できない。
本発明の目的は、かかる問題点を解決し、該排
ガス中のN2Ｏの高収率でNOに転換し、得られた
NOをさらに硝酸として、経済的に有利に回収
し、ジカルボン酸製造の原料に再利用する方法を
提供するにある。
（問題点を解決するための手段および作用）
上記目的を達成する本発明は、シクロアルカノ
ールおよび／またはシクロアルカノンを硝酸酸化
してジカルボン酸を製造するに際し、副生する
N2Ｏ，NO，NO2を含む排ガス中のNOおよび
NO2を合わせて10％以下にした後、該排ガスを
実質的に押出し流れ状態で無触媒熱分解すること
によつて、該排ガス中のN2ＯをNOに転換し、さ
らにNOを水に吸収させて硝酸に転換し、該回収
硝酸を再びジカルボン酸製造の原料に供すること
を特徴とする。
すなわち、N2Ｏの熱分解反応は
(1) N2Ｏ→N2＋１／２O2＋19.5 Kca／mo・N2
Ｏ
(2) N2Ｏ→NO＋１／２N2−1.96 Kca／mo・
N2Ｏ
の並発反応であるが、触媒を使用して接触分解を
行うと、ほとんど(1)の反応だけが起こるため、(2)
は得られない。一方、無触媒の高温領域では、相
対的に(1)(2)の反応速度が近づいてくるため、NO
の生成が認められてくる。
本発明は、該酸化排ガスの処理にあたり、無触
媒で加熱分解し、N2ＯをNOに転換し、さらに、
これを有価な硝酸として回収することを特徴とす
る。
本発明者らは、該酸化排ガス中のN2Ｏの熱分
解反応によるNOへの転化率について、回分式の
槽型反応器を用いて共存ガスの影響を克明に検討
し、共存ガスのうち従来知られていたNOの他
に、NO2の存在は、第１図に示すように、NO転
化率を大きく妨害することを見い出した。
NOおよびNO2は、該酸化排ガス中に多量含ま
れる他、N2Ｏの熱分解によりNOが生成し、これ
はやはりN2Ｏの分解で得られたO2と反応し、一
部NO2になるため、熱分解生成ガス中にもNOお
よびNO2が含まれる。そのためN2Ｏの反応ゾー
ンにおけるNOおよびNO2の存在量は、第２図に
示すように、反応器の型式により大きな影響を受
ける。すなわち、完全混合流れでは、N2Ｏを含
む該酸化排ガス中に同伴するNO，NO2およびN2
Ｏの分解で生成したNO，NO2が均一に混合する
ため、妨害作用は最も大きい。
一方、押出し流れでは、流れの進行方向に混合
作用がないため、N2Ｏの熱分解で生成したNO，
NO2の妨害は排除できる。しかし、該酸化排ガ
ス中にはじめから同伴するNO，NO2の妨害作用
は、完全混合流れに比べると小さいが、同伴量が
あまり多いと好ましいことではなく、該酸化排ガ
ス中に含まれるNOおよびNO2を合わせて10％以
下に、予め除去することが好ましい。
該酸化排ガス中に含まれるNOおよびNO2の除
去は、空気酸化の後、低温で水による吸収反応を
行なえば、N2Ｏはそのままで、NO，NO2は容易
に硝酸として除去できるが、N2Ｏの加熱分解で
得られるNOおよびNO2は高温のため、このまま
では容易に除去できない。そのため、反応炉が完
全混合型の時は、生成NOおよびNO2がN2Ｏと混
合するため、直接影響を受け、高いNO収率は得
られない。
これらのことから、反応炉は押出し流れにする
ことが不可欠である。すなわち、本発明は、該酸
化排ガス中に含まれるNOおよびNO2を合わせて
10％以下に除去した後、排ガス中のN2Ｏを流れ
の進行方向に混合作用のない、実質的に押出し流
れで熱分解することによつて、共存ガスの影響を
排除し、高いNO収率を得ることを特徴とする。
本発明において使用する押出し流れ反応器の一
つのモデルを第３図に示した。
第３図は、生成ガスと熱交換の可能な管式反応
器である。該酸化排ガスは導管１を経て反応管２
に導かれ、はじめ分解生成ガスで予熱され次第に
昇温すると約900℃で反応が始まり、分解熱を発
生する。分解熱でさらに昇温され、N2Ｏが反応
管２出口に達するまでに反応は完結する。高温の
分解生成ガスは、連絡管３を経て反応炉４に戻さ
れ、該酸化排ガスと熱交換した後、反応炉出口５
に達する。なお、最初の昇温は、別に設けた熱風
発生機で行い、反応炉４は蓄熱できる構造になつ
ている。
管式反応器は理想的な押出し流れが実現できる
他、ガス線速を大きくとれるため、伝熱係数が大
きく、反応温度の調節にも有効である。しかしな
がら、本発明によれば、反応器の型式は実質的に
押出し流れならばどんな型式でもよく、管式反応
器に限定するものではない。
N2Ｏを含む排ガスの熱分解において、N2Ｏの
NOへの転化率を左右するその他の重要な因子
は、反応温度と滞留時間である。押出し流れの反
応炉においては、反応温度の上昇とともにNOへ
の転化率が上昇するが、約1200℃以上になると、
第４図に示すように、ほとんど変わらなくなる。
N2Ｏ初濃度は高いほどN2Ｏの分解速度は速くな
るが、NOへの転化率は僅かに上昇する程度であ
る。
滞留時間はN2Ｏの分解率を維持するため、N2
Ｏ分圧、反応温度と関連して、必要な滞留時間は
とらねばならないが、あまり長くなると、第５図
に示すように、NO収率は悪化する。この原因
は、滞留時間が長くなると、発生したNOがさら
にNO→１／２N2＋１／２O2に反応が進行するためと
考えられる。
これらのことから、N2ＯのNOへの転化率を最
大ならしめる熱分解条件として可能な範囲は、該
酸化排ガスに同伴されるNOおよびNO2を合わせ
て10％以下に処理した後、実質的に押出し流れで
反応温度1000〜1300℃、滞留時間0.01〜100秒を
選べばよく、さらに好ましくは、NOおよびNO2
を合わせて５％以下に処理した後、実質的に押出
し流れで、反応温度1100〜1200℃、滞留時間0.01
〜10秒を選ぶのがよく、この条件では経済的で、
設備費的にも極めて有利になる。
本発明は、該酸化排ガス中のN2Ｏを加熱分解
するに際し、自己分解熱で反応温度を維持しなが
ら、N2ＯをNOに転換し、さらに、それを連続的
に硝酸として回収し、ジカルボン酸の原料として
再利用する経済的に有利なシステムを提供する。
例えば、シクロヘキサノールおよび／またはシ
クロヘキサノンを硝酸酸化してアジピン酸を製造
するプロセスにおいて発生する排ガスは、一般に
N2O40〜60％，NO5〜10％，NO210〜20％，CO2
５〜10％，H2O20〜30％，HNO3１〜５％，N2
１〜５％から成る。該排ガス中のN2Ｏを熱分解
し、得られたNOを硝酸として回収し、再び酸化
反応に供与するプロセスについて、基本的流れを
示すブロツク系統図（第６図）に基いて、以下に
詳しく説明する。
アジピン酸の主要な製造工程は、反応工程８、
晶析分離工程９、洗浄工程１０、乾燥工程１１、
製品化工程１２からなる反応器８において、シク
ロヘキサノールおよび／またはシクロヘキサノン
６と硝酸７と反応させると、アジピン酸の生成と
ともに、N2Ｏ，NO，NO2，CO2等の副生ガスが
多量発生する。副生ガス１４は所定量の空気１５
とともに、排ガス処理工程に導かれる。
該酸化排ガスは、まず、水封式ポンプ１６で１
〜２Kg／cm2・Ｇに加圧し、酸化塔１７で含有する
NOをNO2に酸化した後、吸収塔１８に導き、
NO，NO2を硝酸に転換する。NO，NO2を除去
した該排ガスは、予め熱風発生機で昇温されたピ
ストン流反応器１９に導き、N2Ｏの熱分解反応
を行う。該反応器において、N2Ｏを含む排ガス
は、N2Ｏが分解してできた高温の生成ガスと熱
交換できる構造になつており、排ガス中のN2Ｏ
は、この熱分解生成ガスによつて、はじめ予熱さ
れ、約900℃に昇温した点で分解反応が始まる。
分解熱によつてさらに温度が上昇し、反応管出口
で丁度分解反応が完結する。反応温度は、高温の
分解生成ガスの熱交換量をバイパスラインを使用
して調節することにより、一定に保たれる。
N2Ｏを含む排ガスの予熱に使用した後の分解
生成ガスは、なお温度が高いため、ボイラー２
０，２１に導き、分解生成ガスの保有熱で水を蒸
気に変換する。発生した蒸気２３は、アジピン酸
製造プロセスに利用する。また、ボイラーには発
生した蒸気に見合う補給水２２を供給する。その
後、熱分解生成ガスは、熱交換機２４に導き冷却
水２５でほぼ常温まで冷却し、吸収塔２７に導き
熱分解生成ガス中のNO，NO2を吸収水２６と反
応させることによつて、硝酸に転換する。
NO，NO2を硝酸として回収した残りの排ガス
は、主として、N2，O2，CO2，H2Ｏからなり、
大気に放棄される。一方、N2Ｏの熱分解で得ら
れたNO，NO2は、硝酸として回収し、さらに吸
収塔１８の吸収液に利用した後、新硝酸１３と混
合し、シクロヘキサノールおよび／またはシクロ
ヘキサノンの酸化反応に再び利用する。
（実施例）
以下、本発明を実施例により説明する。
実施例 １
シクロヘキサノールとシクロヘキサノンの混合
物（60／40w／ｗ）を硝酸酸化してアジピン酸を
製造するプロセスにおいて発生する酸化排ガス
を、第６図に示したプロセスフローにしたがつ
て、まず、吸収塔に導き、共存するNO，NO2を
除去する。
NO，NO2を除去した後のガス組成を表１に示
す。
(Industrial Application Field) The present invention processes exhaust gas containing N 2 O produced as a by-product when producing dicarboxylic acid by oxidizing cycloalkanol and/or cycloalkanone using nitric acid. The present invention relates to an advantageous dicarboxylic acid production method that can reduce production costs by efficiently converting N 2 O in the exhaust gas, which has no utility value, into valuable nitric acid and reusing it. (Prior art) When producing dicarboxylic acid by oxidizing cycloalkanol and/or cycloalkanone using nitric acid, the gas produced by-product is generally N 2
O, NO, NO 2 , O 2 , CO 2 , H 2 O, HNO 3 , N 2
Consisting of Of these, NO and NO 2 are recovered as nitric acid by an absorption reaction with water after air oxidation, but N 2 O cannot be recovered as it is, so it is decomposed into N 2 and O 2 by catalytic cracking. After that,
It is released into the atmosphere along with other exhaust gases. Although not directly related to the exhaust gas generated during the production of dicarboxylic acids, there are many known techniques for treating exhaust gas containing N 2 O by catalytic cracking.
Recent examples include US Pat. No. 4,259,303 ('81). According to this, when processing N 2 O in waste anesthetic gas,
Using NiO, Fe 2 O 3 , etc. as a catalyst, the reaction temperature is 350~
When the catalytic cracking reaction is carried out at 550° C. for a residence time of 4 to 9 seconds, N 2 O can be decomposed to almost 100% N 2 and O 2 . However, these catalytic cracking techniques
This process only detoxifies exhaust gas containing N 2 O into N 2 and O 2 and is not worthy of effective use of N 2 O. On the other hand, when N 2 O undergoes a thermal decomposition reaction without a catalyst, the parallel reactions often occur: (1) N 2 O → N 2 + 1/2 O 2 (2) N 2 O → NO + 1/2 N 2 known and no
Consideration was given to recovering nitric acid from FJLINDARS et al. Proceedings of the Royal Society (London) [Proc.Roy.Soc. (London)] A231 ,
162, ('55), reaction temperature 720℃, residence time
It is reported that the decomposition reaction of N 2 O → NO + 1/2 N 2 progresses by about 5% in 1830 seconds. (Problems to be Solved by the Invention) Treating exhaust gas containing N 2 O by catalytic cracking in the method described in the prior art decomposes N 2 O into worthless N 2 and O 2 . This does not satisfy the purpose of effective use of N 2 O. On the other hand, past techniques related to non-catalytic thermal decomposition reactions that convert N 2 O into NO and from which nitric acid can be obtained have low NO yields and are economically problematic. Furthermore, according to the present inventors, the prior art uses an oxidizing exhaust gas (hereinafter simply referred to as " In the case of a large amount of coexisting gases (NO, NO 2 , CO 2 , HNO 3 , O 2 ,
N2 ), so it cannot be applied. The purpose of the present invention is to solve such problems, convert N 2 O in the exhaust gas into NO with a high yield, and
It is an object of the present invention to provide a method for economically advantageously recovering NO as nitric acid and reusing it as a raw material for producing dicarboxylic acid. (Means and effects for solving the problems) The present invention achieves the above objects by producing dicarboxylic acids by oxidizing cycloalkanols and/or cycloalkanones with nitric acid.
NO and NO in exhaust gas including N 2 O, NO, NO 2
After reducing the total amount of NO 2 to 10% or less, the exhaust gas is subjected to non-catalytic thermal decomposition in a substantially extrusion flow state to convert the N 2 O in the exhaust gas to NO, and further convert NO to water. It is characterized in that it is absorbed and converted into nitric acid, and the recovered nitric acid is again used as a raw material for producing dicarboxylic acid. That is, the thermal decomposition reaction of N 2 O is (1) N 2 O→N 2 +1/2O 2 +19.5 Kca/mo・N 2 O (2) N 2 O→NO+1/2N 2 −1.96 Kca/mo・This is a parallel reaction of N 2 O, but when catalytic cracking is performed using a catalyst, only reaction (1) occurs, so (2)
cannot be obtained. On the other hand, in the high-temperature region without catalyst, the reaction rates of (1) and (2) become relatively close to each other, so NO
The formation of is recognized. The present invention treats the oxidized exhaust gas by thermally decomposing it without a catalyst, converting N 2 O to NO, and further,
It is characterized by recovering this as valuable nitric acid. The present inventors investigated in detail the influence of coexisting gases on the conversion rate of N 2 O in the oxidizing exhaust gas to NO by thermal decomposition reaction using a batch type tank reactor, and found that among the coexisting gases, It has been found that the presence of NO 2 , in addition to the previously known NO, significantly impedes the NO conversion rate, as shown in FIG. NO and NO 2 are contained in large amounts in the oxidizing exhaust gas, and NO is generated by thermal decomposition of N 2 O. This also reacts with O 2 obtained by decomposing N 2 O, and some NO 2 Therefore, NO and NO 2 are also included in the pyrolysis product gas. Therefore, the amount of NO and NO 2 present in the N 2 O reaction zone is greatly influenced by the type of reactor, as shown in FIG. That is, in a completely mixed flow, NO, NO 2 and N 2 entrained in the oxidizing exhaust gas containing N 2 O
Since NO and NO 2 produced by the decomposition of O are mixed uniformly, the interfering effect is the greatest. On the other hand, in extrusion flow, there is no mixing effect in the direction of flow, so NO, which is generated by thermal decomposition of N 2 O,
NO 2 interference can be eliminated. However, although the interfering effect of NO and NO 2 originally entrained in the oxidizing exhaust gas is small compared to a completely mixed flow, it is not desirable if the entrained amount is too large, and the NO and NO 2 contained in the oxidizing exhaust gas It is preferable to remove 2 in advance to a total of 10% or less. NO and NO 2 contained in the oxidized exhaust gas can be easily removed as nitric acid by performing an absorption reaction with water at a low temperature after air oxidation, while leaving N 2 O as it is. Since NO and NO 2 obtained by thermal decomposition of N 2 O are at high temperatures, they cannot be easily removed as they are. Therefore, when the reactor is of a complete mixing type, NO and NO 2 produced are mixed with N 2 O, which is directly affected, and a high NO yield cannot be obtained. For these reasons, it is essential to use an extrusion flow in the reactor. That is, the present invention combines NO and NO 2 contained in the oxidizing exhaust gas.
After removing N 2 O to 10% or less, the N 2 O in the exhaust gas is thermally decomposed in a substantially extrusion flow with no mixing effect in the direction of flow, thereby eliminating the influence of coexisting gases and achieving high NO yield. It is characterized by obtaining a rate. One model of the extrusion flow reactor used in the present invention is shown in FIG. FIG. 3 shows a tubular reactor capable of exchanging heat with the produced gas. The oxidizing exhaust gas passes through conduit 1 to reaction tube 2.
The reaction begins at approximately 900°C, and heat of decomposition is generated. The temperature is further increased by the heat of decomposition, and the reaction is completed by the time N 2 O reaches the outlet of the reaction tube 2. The high-temperature decomposition gas is returned to the reactor 4 via the connecting pipe 3, and after exchanging heat with the oxidized exhaust gas, it is sent to the reactor outlet 5.
reach. Note that the initial temperature increase is performed by a separately provided hot air generator, and the reactor 4 has a structure that can store heat. In addition to being able to achieve an ideal extrusion flow, the tubular reactor allows for a high gas linear velocity, resulting in a large heat transfer coefficient and is effective in controlling the reaction temperature. However, according to the present invention, the type of reactor may be substantially any type as long as it has an extrusion flow, and is not limited to a tubular reactor. In the thermal decomposition of exhaust gas containing N 2 O, N 2 O is
Other important factors influencing the conversion to NO are reaction temperature and residence time. In extrusion flow reactors, the conversion rate to NO increases as the reaction temperature increases, but at temperatures above about 1200℃,
As shown in Figure 4, there is almost no difference.
The higher the initial concentration of N 2 O, the faster the decomposition rate of N 2 O, but the conversion rate to NO increases only slightly. The residence time is determined to maintain the decomposition rate of N 2 O.
The necessary residence time must be set in relation to the O partial pressure and the reaction temperature, but if it is too long, the NO yield will deteriorate as shown in FIG. The reason for this is thought to be that as the residence time becomes longer, the reaction of the generated NO further progresses from NO to 1/2N 2 + 1/2O 2 . Based on these facts, the possible range of thermal decomposition conditions that maximizes the conversion rate of N 2 O to NO is to Generally speaking, a reaction temperature of 1000 to 1300°C and a residence time of 0.01 to 100 seconds may be selected for the extrusion flow, and more preferably, NO and NO 2
After processing to a total of 5% or less, the reaction temperature is 1100-1200℃, residence time is 0.01, substantially in an extrusion flow.
It is best to choose ~10 seconds, which is economical under these conditions,
It is also extremely advantageous in terms of equipment costs. The present invention, when thermally decomposing N 2 O in the oxidizing exhaust gas, converts the N 2 O into NO while maintaining the reaction temperature using self-decomposition heat, and further recovers it continuously as nitric acid. To provide an economically advantageous system for reusing dicarboxylic acid as a raw material. For example, the exhaust gas generated in the process of producing adipic acid by oxidizing cyclohexanol and/or cyclohexanone with nitric acid is generally
N 2 O 40-60%, NO 5-10%, NO 2 10-20%, CO 2
5-10%, H2O20-30 %, HNO3 1-5%, N2
It consists of 1-5%. The process of thermally decomposing N 2 O in the exhaust gas, recovering the obtained NO as nitric acid, and supplying it again to the oxidation reaction is described below based on the block diagram (Figure 6) showing the basic flow. explain in detail. The main manufacturing steps for adipic acid are reaction step 8,
Crystallization separation step 9, washing step 10, drying step 11,
When cyclohexanol and/or cyclohexanone 6 is reacted with nitric acid 7 in the reactor 8 comprising the product production step 12, adipic acid is produced and a large amount of by-product gases such as N 2 O, NO, NO 2 and CO 2 are produced. Occur. Byproduct gas 14 is a predetermined amount of air 15
At the same time, it is led to the exhaust gas treatment process. The oxidizing exhaust gas is first pumped through a water ring pump 16.
Pressurized to ~2Kg/ cm2・G and contained in oxidation tower 17
After oxidizing NO to NO 2 , it is led to the absorption tower 18,
Converts NO, NO 2 to nitric acid. The exhaust gas from which NO and NO 2 have been removed is led to a piston flow reactor 19 whose temperature has been raised in advance by a hot air generator, where a thermal decomposition reaction of N 2 O is carried out. In this reactor, the structure is such that the exhaust gas containing N 2 O can exchange heat with the high-temperature gas produced by decomposing N 2 O.
is first preheated by this thermal decomposition gas, and the decomposition reaction begins when the temperature rises to approximately 900°C.
The temperature further rises due to the heat of decomposition, and the decomposition reaction is just completed at the outlet of the reaction tube. The reaction temperature is kept constant by adjusting the amount of heat exchange of the hot decomposition product gas using a bypass line. After being used to preheat the exhaust gas containing N 2 O, the decomposition gas is still at a high temperature, so the boiler 2
0.21, and the heat retained in the decomposed gas converts water into steam. The generated steam 23 is used in the adipic acid production process. Also, makeup water 22 is supplied to the boiler in proportion to the generated steam. Thereafter, the pyrolysis product gas is led to a heat exchanger 24 and cooled to approximately room temperature with cooling water 25, and then led to an absorption tower 27 where NO and NO 2 in the pyrolysis product gas are reacted with absorbed water 26, thereby Converts to nitric acid. The remaining exhaust gas after recovering NO and NO 2 as nitric acid mainly consists of N 2 , O 2 , CO 2 and H 2 O.
Abandoned to the atmosphere. On the other hand, NO and NO 2 obtained by thermal decomposition of N 2 O are recovered as nitric acid and used as an absorption liquid in the absorption tower 18, and then mixed with fresh nitric acid 13 to oxidize cyclohexanol and/or cyclohexanone. Use again for reaction. (Example) Hereinafter, the present invention will be explained with reference to Examples. Example 1 The oxidized exhaust gas generated in the process of producing adipic acid by oxidizing a mixture of cyclohexanol and cyclohexanone (60/40 w/w) with nitric acid was first absorbed and absorbed according to the process flow shown in Figure 6. It is led to a column and coexisting NO and NO 2 are removed. Table 1 shows the gas composition after removing NO and NO 2 .
【表】
該処理ガスを下記の条件で熱分解を行つたとこ
ろ、表２の結果を得た。なお、ガス組成は乾きガ
ス組成を示す。
〈分解条件〉
温度1054℃、圧力0.5Kg／cm2Ｇ
実ガス線速44.7cm／sec
滞留時間1.2sec
ガス流量2.87Nm3／Hr[Table] When the treated gas was thermally decomposed under the following conditions, the results shown in Table 2 were obtained. Note that the gas composition indicates a dry gas composition. <Decomposition conditions> Temperature 1054℃, pressure 0.5Kg/cm 2 G Actual gas linear velocity 44.7cm/sec Residence time 1.2sec Gas flow rate 2.87Nm 3 /Hr
【表】
これよりN2ＯのNOへの転化率は25.4％とな
り、残りはN2，O2に分解し、未反応N2Ｏは認め
られなかつた。
なお、分解後ガス組成で、NOよりNO2が多い
のは、生成したNOは直ちに酸化され、一部NO2
になるためである。
N2Ｏの熱分解により得られたNO，NO2は、吸
収塔で硝酸として回収される。回収された硝酸は
1044ｇ／hrであつた。
実施例 ２
実施例１と同様に酸化排ガスに含まれるNO，
NO2を処理した後、下記の条件で熱分解を行つ
たところ、表３の結果を得た。
〈分解条件〉
温度1210℃、圧力0.2Kg／cm2・Ｇ
実ガス線速10.4cm／sec
滞留時間37.8sec
ガス流量2.03Nm3／Hr[Table] From this, the conversion rate of N 2 O to NO was 25.4%, the remainder was decomposed into N 2 and O 2 , and no unreacted N 2 O was observed. In addition, the reason that there is more NO 2 than NO in the gas composition after decomposition is that the generated NO is immediately oxidized and some NO 2
This is to become. NO and NO 2 obtained by thermal decomposition of N 2 O are recovered as nitric acid in an absorption tower. The recovered nitric acid is
It was 1044g/hr. Example 2 Similar to Example 1, NO contained in the oxidized exhaust gas,
After treating NO 2 , thermal decomposition was performed under the following conditions, and the results shown in Table 3 were obtained. <Decomposition conditions> Temperature 1210℃, pressure 0.2Kg/cm 2・G Actual gas linear velocity 10.4cm/sec Residence time 37.8sec Gas flow rate 2.03Nm 3 /Hr
【表】
これよりN2ＯのNOへの転化率は20.5％にな
る。また、生成NOから得られた回収硝酸は539
ｇ／Hrであつた。
実施例 ３
実施例１と同様に酸化排ガスに含まれるNO，
NO2を処理した後、下記の条件で熱分解を行つ
たところ、表４の結果を得た。
〈分解条件〉
温度985℃、圧力1.2Kg／cm2・Ｇ
実ガス線速82.8cm／sec
滞留時間0.15sec
ガス流量3.67Nm3／Hr[Table] From this, the conversion rate of N 2 O to NO is 20.5%. In addition, the recovered nitric acid obtained from the generated NO is 539
It was hot at g/hr. Example 3 Similar to Example 1, NO contained in the oxidized exhaust gas,
After treating NO 2 , thermal decomposition was performed under the following conditions, and the results shown in Table 4 were obtained. <Decomposition conditions> Temperature 985℃, pressure 1.2Kg/cm 2・G Actual gas linear velocity 82.8cm/sec Residence time 0.15sec Gas flow rate 3.67Nm 3 /Hr
【表】【table】
【表】
これよりN2ＯのNOへの転化率は23.4％にな
る。また、生成NOから得られた回収硝酸は1217
ｇ／Hrであつた。
（発明の効果）
従来、シクロアルカノールおよび／またはシク
ロアルカノンを硝酸酸化してジカルボン酸を製造
するに際し、大量に副生するN2Ｏは、このまま
では回収できないため、そのまま、あるいは接触
分解により、N2，O2に転換し、廃棄していた。
本発明によれば、該酸化排ガス中のN2Ｏを詳
細に説明した熱分解条件で高収率でNOに転換
し、これを空気酸化した後、水による吸収反応に
よつて硝酸に回収し、該回収硝酸を再びジカルボ
ン酸の原料として再利用することによつて、ジカ
ルボン酸の製造コストを大きく改善できる。ま
た、高濃度のN2Ｏは麻酔作用があるため、直接
廃棄することは好ましいことではないが、本発明
によれば、N2Ｏは完全に分解でき、NO，N2，
O2に転換するため、NOを硝酸として回収できる
と同時に、無害化も達成できる。さらに分解に伴
つて発生する高い分解熱を利用すれば、これを蒸
気エネルギーに変換することも可能である。[Table] From this, the conversion rate of N 2 O to NO is 23.4%. In addition, the recovered nitric acid obtained from the generated NO is 1217
It was hot at g/hr. (Effect of the invention) Conventionally, when producing dicarboxylic acids by oxidizing cycloalkanols and/or cycloalkanones with nitric acid, a large amount of N 2 O, which is produced as a by-product, cannot be recovered as is. It was converted to N 2 and O 2 and disposed of. According to the present invention, N 2 O in the oxidized exhaust gas is converted into NO in a high yield under the detailed thermal decomposition conditions, and after air oxidation, it is recovered to nitric acid through an absorption reaction with water. By reusing the recovered nitric acid as a raw material for dicarboxylic acid, the manufacturing cost of dicarboxylic acid can be greatly improved. Furthermore, because high concentrations of N 2 O have an anesthetic effect, it is not preferable to dispose of them directly, but according to the present invention, N 2 O can be completely decomposed and converted into NO, N 2 ,
Because it is converted to O 2 , NO can be recovered as nitric acid, and at the same time, it can also be made harmless. Furthermore, by utilizing the high heat of decomposition generated during decomposition, it is possible to convert this into steam energy.
第１図は該酸化排ガス中のN2Ｏの熱分解反応
によるNOへの転化率に及ぼすNOおよびNO2の
影響を示すグラフ、第２図は同じくNOおよび
NO2の存在量と反応炉型式による影響を示すグ
ラフ、第３図は本発明において使用する管式反応
器の説明図、第４図はNOへの転化率に及ぼす温
度の影響を示すグラフ、第５図はNOへの転化率
に及ぼす滞留時間の影響を示すグラフ、第６図は
本発明の基本的流れを示すブロツク系統図であ
る。
Figure 1 is a graph showing the influence of NO and NO 2 on the conversion rate of N 2 O in the oxidizing exhaust gas to NO by the thermal decomposition reaction, and Figure 2 is a graph showing the influence of NO and
A graph showing the amount of NO 2 present and the influence of the reactor type, Fig. 3 is an explanatory diagram of the tubular reactor used in the present invention, Fig. 4 is a graph showing the effect of temperature on the conversion rate to NO, FIG. 5 is a graph showing the effect of residence time on the conversion rate to NO, and FIG. 6 is a block diagram showing the basic flow of the present invention.
Claims (1)
ルカノンを硝酸酸化してジカルボン酸を製造する
に際し、副生する亜酸化窒素（N2Ｏ）、酸化窒素
（NO）、二酸化窒素（NO2）を含む排ガス中の酸
化窒素および二酸化窒素を合わせて10％以下にし
た後、該排ガスを実質的に押出し流れ状態で無触
媒熱分解することによつて、該排ガス中の亜酸化
窒素を酸化窒素に転換し、さらに酸化窒素を水に
吸収させて硝酸に転換し、該回収硝酸を再びジカ
ルボン酸製造の原料に供することを特徴とするジ
カルボン酸の製造法。 ２ 該酸化排ガス中に含まれる酸化窒素（NO）
および二酸化窒素（NO2）は合わせて５％以下
に処理し、亜酸化窒素（N2Ｏ）の熱分解条件は
実質的に押出し流れ状態で、かつ反応温度1000〜
1300℃、滞留時間0.01〜100秒である特許請求の
範囲第１項記載のジカルボン酸の製造法。[Claims] 1. Nitrous oxide (N 2 O), nitrogen oxide (NO), nitrogen dioxide (NO 2 ) After reducing the total amount of nitrogen oxide and nitrogen dioxide in the exhaust gas to 10% or less, nitrous oxide in the exhaust gas is oxidized by non-catalytic thermal decomposition of the exhaust gas in a substantially extrusion flow state. A method for producing dicarboxylic acid, which comprises converting it into nitrogen, further absorbing the nitrogen oxide into water to convert it into nitric acid, and using the recovered nitric acid again as a raw material for producing dicarboxylic acid. 2 Nitrogen oxide (NO) contained in the oxidizing exhaust gas
and nitrogen dioxide (NO 2 ) are treated to a total of 5% or less, and the thermal decomposition conditions for nitrous oxide (N 2 O) are substantially in an extrusion flow state, and the reaction temperature is 1000~1000℃.
The method for producing a dicarboxylic acid according to claim 1, wherein the temperature is 1300°C and the residence time is 0.01 to 100 seconds.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10037385A JPS61257940A (en) | 1985-05-13 | 1985-05-13 | Production of dicarboxylic acid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10037385A JPS61257940A (en) | 1985-05-13 | 1985-05-13 | Production of dicarboxylic acid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61257940A JPS61257940A (en) | 1986-11-15 |
| JPH0579657B2 true JPH0579657B2 (en) | 1993-11-04 |
Family
ID=14272230
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10037385A Granted JPS61257940A (en) | 1985-05-13 | 1985-05-13 | Production of dicarboxylic acid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61257940A (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4128629A1 (en) * | 1991-08-29 | 1993-03-04 | Basf Ag | SILVER-CONTAINING CARRIER CATALYST AND METHOD FOR THE CATALYTIC DECOMPOSITION OF NITROGEN MONOXIDE |
| FR2687138A1 (en) † | 1992-02-07 | 1993-08-13 | Hoechst France | PROCESS FOR THERMOCHEMICAL OXIDATION OF DIAZOTE OXIDE |
| FR2709748B1 (en) * | 1993-09-10 | 1995-10-27 | Rhone Poulenc Chimie | Process for the plasmachemical transformation of N2O into NOx and / or its derivatives. |
| US5472680A (en) * | 1994-01-26 | 1995-12-05 | E. I. Du Pont De Nemours And Company | Production of NO from N2 O |
| WO1999025461A1 (en) * | 1997-11-18 | 1999-05-27 | Asahi Kasei Kogyo Kabushiki Kaisha | Method and device for global warming prevention |
| TWI238157B (en) | 2001-01-25 | 2005-08-21 | Asahi Kasei Corp | Process for producing alkanedicarboxylic acid |
| US8920539B2 (en) * | 2010-09-22 | 2014-12-30 | Koninklijke Philips N.V. | Method and arrangement for generating oxygen and nitric oxide |
| CN103649029B (en) * | 2011-07-12 | 2015-10-14 | 旭化成化学株式会社 | Cyclohexanol, method for producing cyclohexanol, and method for producing adipic acid |
| CN102826521B (en) * | 2012-08-30 | 2014-03-12 | 安徽淮化股份有限公司 | Control system of nitrogen dioxide content |
| US10723624B2 (en) * | 2017-12-05 | 2020-07-28 | Ascend Performance Materials Operations Llc | Process for preparation of nitrogen oxides and nitric acid from nitrous oxide |
| CN116764372A (en) * | 2021-12-27 | 2023-09-19 | 孙碧婷 | A three-stage exhaust gas purification tower with high concentration of nitrogen oxides |
-
1985
- 1985-05-13 JP JP10037385A patent/JPS61257940A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61257940A (en) | 1986-11-15 |
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