NO115736B - - Google Patents
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- NO115736B NO115736B NO159406A NO15940665A NO115736B NO 115736 B NO115736 B NO 115736B NO 159406 A NO159406 A NO 159406A NO 15940665 A NO15940665 A NO 15940665A NO 115736 B NO115736 B NO 115736B
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- Prior art keywords
- formaldehyde
- stage
- absorption
- column
- water
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- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 142
- 239000007789 gas Substances 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 31
- 238000010521 absorption reaction Methods 0.000 claims description 24
- 238000000034 method Methods 0.000 claims description 20
- 239000007788 liquid Substances 0.000 claims description 17
- 239000000203 mixture Substances 0.000 claims description 11
- 150000005846 sugar alcohols Polymers 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 5
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- 150000002373 hemiacetals Chemical class 0.000 claims description 3
- 238000003786 synthesis reaction Methods 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 238000005979 thermal decomposition reaction Methods 0.000 claims description 2
- 239000000945 filler Substances 0.000 description 7
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 7
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- 239000012495 reaction gas Substances 0.000 description 5
- ZJCCRDAZUWHFQH-UHFFFAOYSA-N Trimethylolpropane Chemical compound CCC(CO)(CO)CO ZJCCRDAZUWHFQH-UHFFFAOYSA-N 0.000 description 4
- 238000003776 cleavage reaction Methods 0.000 description 4
- 230000007017 scission Effects 0.000 description 4
- 229940113165 trimethylolpropane Drugs 0.000 description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- 239000002274 desiccant Substances 0.000 description 3
- MGJURKDLIJVDEO-UHFFFAOYSA-N formaldehyde;hydrate Chemical compound O.O=C MGJURKDLIJVDEO-UHFFFAOYSA-N 0.000 description 3
- 238000000197 pyrolysis Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- ARXKVVRQIIOZGF-UHFFFAOYSA-N 1,2,4-butanetriol Chemical compound OCCC(O)CO ARXKVVRQIIOZGF-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- HNRMPXKDFBEGFZ-UHFFFAOYSA-N ethyl trimethyl methane Natural products CCC(C)(C)C HNRMPXKDFBEGFZ-UHFFFAOYSA-N 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- WXZMFSXDPGVJKK-UHFFFAOYSA-N pentaerythritol Chemical compound OCC(CO)(CO)CO WXZMFSXDPGVJKK-UHFFFAOYSA-N 0.000 description 2
- DNIAPMSPPWPWGF-GSVOUGTGSA-N (R)-(-)-Propylene glycol Chemical compound C[C@@H](O)CO DNIAPMSPPWPWGF-GSVOUGTGSA-N 0.000 description 1
- YAXKTBLXMTYWDQ-UHFFFAOYSA-N 1,2,3-butanetriol Chemical compound CC(O)C(O)CO YAXKTBLXMTYWDQ-UHFFFAOYSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- FBPFZTCFMRRESA-FSIIMWSLSA-N D-Glucitol Natural products OC[C@H](O)[C@H](O)[C@@H](O)[C@H](O)CO FBPFZTCFMRRESA-FSIIMWSLSA-N 0.000 description 1
- FBPFZTCFMRRESA-KVTDHHQDSA-N D-Mannitol Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-KVTDHHQDSA-N 0.000 description 1
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 1
- 239000004386 Erythritol Substances 0.000 description 1
- UNXHWFMMPAWVPI-UHFFFAOYSA-N Erythritol Natural products OCC(O)C(O)CO UNXHWFMMPAWVPI-UHFFFAOYSA-N 0.000 description 1
- 229930195725 Mannitol Natural products 0.000 description 1
- 229930040373 Paraformaldehyde Natural products 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- GSEJCLTVZPLZKY-UHFFFAOYSA-N Triethanolamine Chemical compound OCCN(CCO)CCO GSEJCLTVZPLZKY-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000002144 chemical decomposition reaction Methods 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 239000008130 destillate Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- SZXQTJUDPRGNJN-UHFFFAOYSA-N dipropylene glycol Chemical compound OCCCOCCCO SZXQTJUDPRGNJN-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- UNXHWFMMPAWVPI-ZXZARUISSA-N erythritol Chemical compound OC[C@H](O)[C@H](O)CO UNXHWFMMPAWVPI-ZXZARUISSA-N 0.000 description 1
- 235000019414 erythritol Nutrition 0.000 description 1
- 229940009714 erythritol Drugs 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000008098 formaldehyde solution Substances 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- UFAPLAOEQMMKJA-UHFFFAOYSA-N hexane-1,2,5-triol Chemical compound CC(O)CCC(O)CO UFAPLAOEQMMKJA-UHFFFAOYSA-N 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000000594 mannitol Substances 0.000 description 1
- 235000010355 mannitol Nutrition 0.000 description 1
- SLCVBVWXLSEKPL-UHFFFAOYSA-N neopentyl glycol Chemical compound OCC(C)(C)CO SLCVBVWXLSEKPL-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920002866 paraformaldehyde Polymers 0.000 description 1
- AALKGALVYCZETF-UHFFFAOYSA-N pentane-1,2,3-triol Chemical compound CCC(O)C(O)CO AALKGALVYCZETF-UHFFFAOYSA-N 0.000 description 1
- MOIOWCZVZKHQIC-UHFFFAOYSA-N pentane-1,2,4-triol Chemical compound CC(O)CC(O)CO MOIOWCZVZKHQIC-UHFFFAOYSA-N 0.000 description 1
- 229920000151 polyglycol Polymers 0.000 description 1
- 239000010695 polyglycol Substances 0.000 description 1
- 229920006324 polyoxymethylene Polymers 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- -1 rhamnite Chemical compound 0.000 description 1
- 239000000600 sorbitol Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920001169 thermoplastic Polymers 0.000 description 1
- 239000004416 thermosoftening plastic Substances 0.000 description 1
- ZIBGPFATKBEMQZ-UHFFFAOYSA-N triethylene glycol Chemical class OCCOCCOCCO ZIBGPFATKBEMQZ-UHFFFAOYSA-N 0.000 description 1
- QXJQHYBHAIHNGG-UHFFFAOYSA-N trimethylolethane Chemical compound OCC(C)(CO)CO QXJQHYBHAIHNGG-UHFFFAOYSA-N 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/783—Separation; Purification; Stabilisation; Use of additives by gas-liquid treatment, e.g. by gas-liquid absorption
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/51—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition
- C07C45/511—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups
- C07C45/515—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds by pyrolysis, rearrangement or decomposition involving transformation of singly bound oxygen functional groups to >C = O groups the singly bound functional group being an acetalised, ketalised hemi-acetalised, or hemi-ketalised hydroxyl group
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C45/00—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds
- C07C45/78—Separation; Purification; Stabilisation; Use of additives
- C07C45/85—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to a chemical modification
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Gas Separation By Absorption (AREA)
Description
Fremgangsmåte til fremstilling av rent, vannfritt formaldehyd i gassform. Process for the production of pure, anhydrous formaldehyde in gaseous form.
Den foreliggende oppfinnelse angår fremstilling av ren, vannfri formaldehydgass ved termisk The present invention relates to the production of pure, anhydrous formaldehyde gas by thermal
spaltning av halvacetaler dannet ved absorbsjon cleavage of hemiacetals formed by absorption
av formaldehyd i flerverdige alkoholer. of formaldehyde in polyhydric alcohols.
Fremstilling av ren, vannfri formaldehydgass er av stor teknisk interesse, da det rene formaldehyd kan polymeriseres til termoplaster Production of pure, anhydrous formaldehyde gas is of great technical interest, as the pure formaldehyde can be polymerized into thermoplastics
med gode egenskaper. Den rene formaldehydgass with good characteristics. The pure formaldehyde gas
er også av interesse som råstoff for syntese av is also of interest as a raw material for the synthesis of
lavmolekylære produkter.low molecular weight products.
Fremstilling av formaldehyd skjer i alminnelighet ved katalytisk gassf aseoksydasj on av Formaldehyde is generally produced by catalytic gas phase oxidation of
metanol med luft. Ved en vanlig prosesstype fås methanol with air. In the case of a common process type is obtained
en reaksjonsgass inneholdende 5—6 volumpro-sent formaldehyd, 7—8 prosent vann, små mengder maursyre og andre forurensninger samt resten oksygen og nitrogen. a reaction gas containing 5-6 volume percent formaldehyde, 7-8 percent water, small amounts of formic acid and other impurities and the rest oxygen and nitrogen.
Formaldehydet utvinnes i alminnelighet fra The formaldehyde is generally extracted from
reaksjonsgassen ved absorbsjon i vann hvorved the reaction gas by absorption in water whereby
man får 37—60 prosents formalinoppløsninger. you get 37-60 percent formalin solutions.
Der er kjent en rekke metoder til rensing av formaldehyd. Disse går i en del tilfelle ut på å overføre formalinoppløsninger (med et formaldehydinnhold av 37—60 prosent) til paraformal-dehyd eller a-polyoksymetylen, som deretter spaltes termisk etter fjernelse av vannet. Denne vel er kostbar, og der kreves ytterligere rense-trinn for å fjerne gjenværende vann efter spaltningen, f. eks. ved kontakt med faste tørkemid-ler eller egnede vaskevæsker, for at gassen skal tilfredsstille vanlige krav til tørrhet. A number of methods are known for purifying formaldehyde. In some cases, these involve transferring formalin solutions (with a formaldehyde content of 37-60 per cent) to paraformaldehyde or α-polyoxymethylene, which are then decomposed thermally after removing the water. This well is expensive, and additional cleaning steps are required to remove residual water after the splitting, e.g. in contact with solid drying agents or suitable washing liquids, so that the gas meets normal requirements for dryness.
En annen metode består i å la formaldehydet reagere med en alifatisk alkohol til en halvformal, som renses og tørkes og derefter spaltes termisk til ren formaldehydgass og fri alkohol. Al-koholen bringes deref ter til å reagere med ytterligere formaldehyd osv. Alle disse fremgangsmåter omfatter rensning av formalinoppløsninger. De er beskrevet nærmere f. eks. U.S. patentskrift nr. 2 848 500 og tysk patentskrift nr. 1 151 250. Another method consists in allowing the formaldehyde to react with an aliphatic alcohol to form a semi-formal, which is purified and dried and then thermally decomposed into pure formaldehyde gas and free alcohol. The alcohol is then reacted with further formaldehyde, etc. All these methods involve the purification of formalin solutions. They are described in more detail, e.g. U.S. patent document no. 2 848 500 and German patent document no. 1 151 250.
Alle disse metoder medfører store energiom-kostninger, da der må avdrives store mengder vann. All these methods entail large energy costs, as large quantities of water must be drained away.
En fremgangsmåte hvor man direkte går ut fra den utspedde formaldehydgass som fås ved en metanoloksydasjon, er beskrevet i belgisk patentskrift nr. 615 778. Reaksjonsgassen passerer her først en kolonne som inneholder fyll-legemer og holdes på 30—100°C. I kolonnen sirkulerer en formaldehydholdig vannoppløsning av en polyhydroksylforbindelse med damptrykk under 2 mm Hg ved 100°C, fortrinnsvis pentaerytrit eller trimetylolpropan. Vanninnholdet i denne oppløsning er ca. 8—15 pst. En del av reaksjons-gassens formaldehydinnhold absorberes i denne oppløsning, mens resten absorberes i vann i ko-lonnens øvre del eller i en separat kolonne. A method which directly starts from the diluted formaldehyde gas obtained by methanol oxidation is described in Belgian patent document no. 615 778. The reaction gas here first passes through a column containing fillers and is kept at 30-100°C. In the column circulates a formaldehyde-containing water solution of a polyhydroxyl compound with a vapor pressure below 2 mm Hg at 100°C, preferably pentaerythritol or trimethylolpropane. The water content in this solution is approx. 8-15 percent. Part of the formaldehyde content of the reaction gas is absorbed in this solution, while the rest is absorbed in water in the upper part of the column or in a separate column.
Den øvre del av kolonnen med fyll-legemer får foruten vann-formaldehydoppløsningen også tilført resten fra spaltningstrinnet, d.v.s. alkohol med mindre mengder oppløst formaldehyd. In addition to the water-formaldehyde solution, the upper part of the column with filler bodies is also supplied with the residue from the cleavage step, i.e. alcohol with smaller amounts of dissolved formaldehyde.
Bunnuttaket fra kolonnen med fyll-legemer inneholder ca. 8—15 pst. vann. På grunn av det høye vanninnhold, som ved en slik totrinns-prosess ikke kan senkes uten store tap, må blandin-gen avvannes ved inndunsting i vakuum før den termiske spaltning. The bottom extraction from the column with filler bodies contains approx. 8-15 percent water. Due to the high water content, which in such a two-stage process cannot be lowered without major losses, the mixture must be dewatered by evaporation in a vacuum before the thermal decomposition.
Den tørre halvformal fra vakuuminndunst-ningen blir derefter i en pyrolysekolonne ved 120—150°C spaltet i ren formaldehydgass og en fortynnet formaldehyd-alkohol-oppløsning, som føres tilbake til absorbsjonstrinnet. The dry semi-formal from the vacuum evaporation is then split in a pyrolysis column at 120-150°C into pure formaldehyde gas and a diluted formaldehyde-alcohol solution, which is returned to the absorption step.
Også ved denne prosess går der med store energimengder til å avdrive vannet fra den opp-løsning som fås ved absorbsjonen. Som v a kuum-desitillat fås en ca. 20 prosents formalinoppløs-ning, som har' meget begrenset anvendelse og nærmest blir å betrakte som tap. Inndunstingen i vakuum krever dessuten kostbar apparatur. In this process, too, large amounts of energy are used to drive the water away from the solution obtained by absorption. As vacuum destillate, you get approx. 20 per cent formalin solution, which has very limited use and can almost be regarded as a waste. Evaporation in a vacuum also requires expensive equipment.
Ved fremgangsmåten ifølge den foreliggende oppfinnelse fremstilles rent, vannfritt formaldehyd i gassf orm ved adsorbsjon av formaldehyd fra gasser fra formaldehydsyntesen i en flerverdig alkohol, termisk spaltning av den dannede halvacetal og tilbakeføring av den gjenvundne flerverdige alkohol til absorbsjonen, og fremgangsmåten erkarakterisert vedat gassene i et første absorbsjonstrinn ved en temperatur mellem 80 og 130°C føres i motstrøm til en i dette trinn sirkulerende væske bestående av fra 0,3—3 vektprosent vann, 30—60 vektprosent formaldehyd og resten den flerverdige alkohol, at gassene derefter føres i et annet absorbsjonstrinn ved en temperatur mellem 40 og 80°C i motstrøm til en i dette trinn sirkulerende væske som består av en i forhold til den første absonbsjonsvæske mer vannholdig formaldehydalkoholblanding, og at restgassen fra det annet absorbsjonstrinn vaskes ved en temperatur mellem 35 og 55°C ved å føres i motstrøm til vann, hvorunder en del av den sirkulerende væske i trinn 1 uttas og, eventuelt efter tørking, spaltes termisk, absortosjons-væsken fra trinn 2 føres til trinn 1 og vaskevæs-■ken fra trinn 3 sammen med residuet fra den termiske spaltning føres til trinn 2. In the method according to the present invention, pure, anhydrous formaldehyde is produced in gaseous form by adsorption of formaldehyde from gases from the formaldehyde synthesis in a polyhydric alcohol, thermal cleavage of the formed hemiacetal and return of the recovered polyhydric alcohol to absorption, and the method is characterized by the gases in a first absorption stage at a temperature between 80 and 130°C is passed in countercurrent to a liquid circulating in this stage consisting of from 0.3-3% by weight water, 30-60% by weight formaldehyde and the rest the polyhydric alcohol, that the gases are then passed in another absorption stage at a temperature between 40 and 80°C in countercurrent to a liquid circulating in this stage which consists of a formaldehyde-alcohol mixture that is more aqueous than the first absorption liquid, and that the residual gas from the second absorption stage is washed at a temperature between 35 and 55°C by being passed in countercurrent to water, under which part of the circulating liquid in stage 1 is taken out and, possibly after drying, thermally split, the absorption liquid from stage 2 is fed to stage 1 and the washing liquid from stage 3 together with the residue from the thermal splitting is fed to stage 2.
Ved denne fremgangsmåte fås en formaldehydalkoholblanding med så lavt vanninnhold at With this method, a formaldehyde-alcohol mixture is obtained with such a low water content that
den i visse tilfelle kan ledes direkte til spalt-nlngstrinnet. Vann-innholdet i denne utgående blanding er så lavt som fra<x>k—3 pst. Dette med-fører betydelige fordeler fremfor tidligere kjente fremgangsmåter, hvor fjernelsen av vannet ut-gjør en av de vanskeligste'og dyreste arbeidsope-rasjoner og dessuten fører til store tap av formaldehyd. I visse tilfeller bør også halvacetålen som fås ved fremgangsmåten ifølge oppfinnelsen tørkes. Denne tørking kan skje ved hjelp av faste tørkemidler, ved hjelp av motstrøm av tørr luft e.l. og er et betydelig enklere arbeidstrinn enn ved de kjente metoder, hvor store mengder vann måtte fjernes. it can in certain cases be directed directly to the gap-closing step. The water content in this outgoing mixture is as low as from <x>k-3 per cent. This brings significant advantages over previously known methods, where the removal of the water constitutes one of the most difficult and expensive work operations and furthermore leading to large losses of formaldehyde. In certain cases, the semiacetal steel obtained by the method according to the invention should also be dried. This drying can take place with the help of solid drying agents, with the help of counterflow of dry air, etc. and is a significantly simpler work step than with the known methods, where large amounts of water had to be removed.
Fremgangsmåten ifølge oppfinnelsen kan hensiktsmessig utføres på den måte at absorbsjonen i første trinn skjer ved en temperatur av 100—110°C, i annet trinn ved 50—60°C og i tredje trinn ved 40—50°C. The method according to the invention can conveniently be carried out in such a way that the absorption in the first stage takes place at a temperature of 100-110°C, in the second stage at 50-60°C and in the third stage at 40-50°C.
Oppfinnelsen er i det følgende beskrevet nærmere under henvisning til tegningen, som er et oversiktsskjema for prosessen. The invention is described in more detail in the following with reference to the drawing, which is an overview diagram of the process.
Reaksjonsgassen fra en formaldehydreaktor ledes via ledningen 2 inn i en absorbsjonskolon-ne 1, f.eks. inneholdende fyll-legemer. Tempera-turen ved bunnen av kolonnen holdes på 80— 130°C, fortrinsvis 100—110°C. The reaction gas from a formaldehyde reactor is led via line 2 into an absorption column 1, e.g. containing filler bodies. The temperature at the bottom of the column is kept at 80-130°C, preferably 100-110°C.
I kolonnen sirkulerer en formaldehydblan-ding 3, som bare inneholder små mengder vann, V2—5 pst., i alminnelighet 1—3 pst., og 40—50 pst. formaldehyd. Den gass 4 som går ut ved toppen av kolonnen 1, og hvis formaldehyd-vanninnhold nu er steget, ledes inn ved bunnen av en annen kolonne 5, f.eks. likeledes en kolonne inneholdende fyll-legemer. Denne holdes på 40—80°C, fortrinsvis 50—65°C. Her blir en del av formaldehydet i gassen absorbert i en sirkulerende formaldehyd-alkohol-vannblanding 6. Den gass 7 som går ut ved toppen, ledes inn i en kolonne 8, f.eks. en bunnkolonne, som har en topptemperatur av 35—55°C, fortrinsvis 40— 50°C. Ved toppen av denne kolonne 8 blir der til-ført vann 9, og ved bunnen uttas en formalin-oppløsning 10, som tilføres toppen av kolonne 5 sammen med restvæske 11 fra spaltningstrinnet 12. Luften, inneholdende vanndamp og spor av formaldehydgass, strømmer ut i det fri fra toppen av kolonne 8. En del av den blanding 3 som sirkulerer i kolonne 1, ledes enten direkte til spaltningstrinnet 12 eller tørkes ytterligere i en egnet tørkeanordning 13. Den rene formaldehydgass 14 fås ved spaltningen. Fra denne tretrinns-absorbsjon fås herved en halvformal med lavt vanninnhold og allikevel med høyt formaldehydinnhold. A formaldehyde mixture 3 circulates in the column, which contains only small amounts of water, V2-5 per cent, generally 1-3 per cent, and 40-50 per cent formaldehyde. The gas 4 which exits at the top of column 1, and whose formaldehyde-water content has now risen, is led in at the bottom of another column 5, e.g. likewise a column containing filler bodies. This is kept at 40-80°C, preferably 50-65°C. Here, part of the formaldehyde in the gas is absorbed in a circulating formaldehyde-alcohol-water mixture 6. The gas 7 that exits at the top is led into a column 8, e.g. a bottom column, which has a top temperature of 35-55°C, preferably 40-50°C. At the top of this column 8, water 9 is added, and at the bottom a formalin solution 10 is withdrawn, which is added to the top of column 5 together with residual liquid 11 from the cleavage stage 12. The air, containing water vapor and traces of formaldehyde gas, flows out into the free from the top of column 8. A part of the mixture 3 that circulates in column 1 is either led directly to the splitting step 12 or further dried in a suitable drying device 13. The pure formaldehyde gas 14 is obtained during the splitting. From this three-stage absorption, a semi-formal with a low water content and still with a high formaldehyde content is obtained.
Det som.skjer i høytemperaturkolonnen 1, er at der finner sted en tørking av halvformal-blandingen fra kolonne 5 uten at noen vesentlig del av formaldehydet går bort. Selv med et lavt antall overføringsenheter er det lett å få vann-innholdet i gassen opp til en verdi som ligger nær likevektstrykket over den sirkulerende halvformal. Likevektstrykket av formaldehyd over den sirkulerende halvformal er nemlig ganske høyt (200—250 mm Hg), og metningen av gassen ville medføre en betraktelig synkning i formal-dehydinnholdet i den sirkulerende væske. Der synes imidlertid å foreligge en eller annen form for motstand mot masseoverføringen når det gjelder formaldehyd. iKolonne-effekten, målt som forholdet mellem tilveiebrakt konsentra-sj onsf orandring og drivende kraft (forskjellen mellem likevekts-damptrykk og gassens hersk-ende partialtrykk) er 3 til 4 ganger større for vann enn for formaldehyd. Dette kan forklares med at hastigheten av den kjemiske spaltning av halvformalene ved vedkommende temperatu-rer er så lav at den setter en grense for den hastighet hvormed formaldehyd kan avgis til gass-fasen. What happens in the high-temperature column 1 is that the semi-formal mixture from column 5 is dried without any significant part of the formaldehyde being lost. Even with a low number of transfer units, it is easy to get the water content in the gas up to a value close to the equilibrium pressure above the circulating half-form. The equilibrium pressure of formaldehyde above the circulating semi-formal is quite high (200-250 mm Hg), and the saturation of the gas would entail a considerable decrease in the formaldehyde content in the circulating liquid. However, there seems to be some form of resistance to the mass transfer when it comes to formaldehyde. The column effect, measured as the ratio between the provided concentration change and the driving force (the difference between the equilibrium vapor pressure and the prevailing partial pressure of the gas) is 3 to 4 times greater for water than for formaldehyde. This can be explained by the fact that the rate of chemical decomposition of the semi-formals at the relevant temperatures is so low that it sets a limit to the rate at which formaldehyde can be released into the gas phase.
Den halvformal som fås fra absorbsjons-systemet, kan som nevnt ledes direkte til spaltningstrinnet, hvorved der fås en 96—97 prosents formaldehydgass. Hvis man ønsker en renere formaldehydgass, kan halvformalen tørkes ved kontakt med faste tørkemidler eller ved motstrøms-kontakt med tørr luft eller med tørr luft eller ved en passende tørkemetode. Den tørre halvformal blir derefter pyrolysert på i og for seg kjent måte. As mentioned, the semi-formal obtained from the absorption system can be led directly to the decomposition step, whereby a 96-97 percent formaldehyde gas is obtained. If a cleaner formaldehyde gas is desired, the semiformaldehyde can be dried by contact with solid drying agents or by countercurrent contact with dry air or with dry air or by a suitable drying method. The dry semi-formal is then pyrolysed in a manner known per se.
De alkoholer som er særlig anvendelige for prosessen, er slike som har høyt kokepunkt, fortrinsvis over ca. 200°C, ved atmosfæretrykk, og som fortrinsvis har et damptrykk mindre enn 2 mm ved 100°C. F.eks. kan de følgende alkoholer anvendes: Glycerin, høyere polyglykoler, dietylen- og trietylenglykoler, dipropylenglykol, trietanolamin, 1,2,3-butantriol, 1,2,4-butantriol, 1,2,3-pentantriol, 1,2,4-pentantriol, 2,3,4-pentan-<f>criol, 1,2,5-heksantriol, 2,2-dimetyl-l,3-propan-diol, trimetylol-propan, trimetyloletan, erytrit, ramnit, sorbit, mannit og pentaerytrit. The alcohols that are particularly useful for the process are those that have a high boiling point, preferably above approx. 200°C, at atmospheric pressure, and which preferably has a vapor pressure of less than 2 mm at 100°C. For example the following alcohols can be used: Glycerin, higher polyglycols, diethylene and triethylene glycols, dipropylene glycol, triethanolamine, 1,2,3-butanetriol, 1,2,4-butanetriol, 1,2,3-pentanetriol, 1,2,4- pentanetriol, 2,3,4-pentane-<f>criol, 1,2,5-hexanetriol, 2,2-dimethyl-1,3-propane-diol, trimethylol-propane, trimethylolethane, erythritol, rhamnite, sorbitol, mannitol and pentaerythritol.
Eksempel. Example.
Ved bunnen av den første kolonne 1 med fyll-legemer ble der innført 6.000 l/h av en gass bestående av 6 pst. formaldehyd, 7 pst. H20 og resten luft. I kolonnen sirkulerte en oppløsning bestående av 50 pst. formaldehyd, 1,6 pst. vann og resten trimetylolpropan. Av denne oppløsning ble 1.00 kg/h tatt ut som bunnprodukt. Kolonnen arbeidet ved 102°C. At the bottom of the first column 1 with filler bodies, 6,000 l/h of a gas consisting of 6% formaldehyde, 7% H20 and the rest air were introduced. A solution consisting of 50% formaldehyde, 1.6% water and the remainder trimethylolpropane circulated in the column. Of this solution, 1.00 kg/h was removed as bottom product. The column operated at 102°C.
Den gass som gikk ut fra toppen av kolonne 1, besto av omtrent 10 pst. formaldehyd, 12 pst. vann, resten luft og ble ledet inn ved bunnen av neste kolonne 5 med fyll-legemer. Størstedelen av gassens formaldehydinnhold ble her absorbert i den sirkulerende halvformal-vann-blanding, hvorav 1.62 kg/h ble innmatet ved toppen av kolonne 1. Sammensetningen av denne opp-løsning er omtrent 48 pst. formaldehyd, 22 pst. vann, rest trimetylolpropan. Kolonne 5 arbeidet ved 60°C. The gas that exited from the top of column 1 consisted of approximately 10 percent formaldehyde, 12 percent water, the rest air and was led into the bottom of the next column 5 with filler bodies. The majority of the formaldehyde content of the gas was here absorbed in the circulating semi-formal-water mixture, of which 1.62 kg/h was fed at the top of column 1. The composition of this solution is approximately 48 percent formaldehyde, 22 percent water, the rest trimethylolpropane. Column 5 worked at 60°C.
Den gass som gikk ut fra toppen av kolonne 5, ble ledet inn nederst i bunnkolonnen 8, som ved toppen ble matet med 0,12 kg/h H20.1 denne kolonne ble det resterende formaldehyd absorbert i vannet. Den gass som gikk ut fra toppen av kolonne 8, Inneholdt foruten luft bare spor av formaldehyd samt 0,42 kg/h H20. Kolonnen arbeidet ved 48°C. The gas that exited from the top of column 5 was led into the bottom of the bottom column 8, which at the top was fed with 0.12 kg/h H 2 O. In this column, the remaining formaldehyde was absorbed into the water. The gas that went out from the top of column 8 contained, apart from air, only traces of formaldehyde and 0.42 kg/h H20. The column operated at 48°C.
Ved bunnen av kolonne 8 gikk der ut formaldehyd-vannoppløsning, som ble ledet inn ved toppen av kolonne 5 sammen med den væske som fremkom som rest efter pyrolyse av den tørkede halvformal. Pyrolyseresten inneholdt 10 pst. formaldehyd, rest trimetylpropan, og ble innmatet med en hastighet av 0,54 kg/h. At the bottom of column 8, a formaldehyde-water solution exited, which was led in at the top of column 5 together with the liquid that appeared as a residue after pyrolysis of the dried semi-formal. The pyrolysis residue contained 10 percent formaldehyde, the remainder trimethylpropane, and was fed at a rate of 0.54 kg/h.
Bunnproduktet fra kolonne 1 ble derefter ledet enten direkte eller via et avvanningstrinn til en apparatur hvor det ble spaltet termisk ved 130—150°C. The bottom product from column 1 was then passed either directly or via a dewatering step to an apparatus where it was thermally split at 130-150°C.
Hvis væsken fra kolonne 1 porolyseres direkte, fås en gass med en renhet av ca. 96 pst. If the liquid from column 1 is porolysed directly, a gas with a purity of approx. 96 percent
De viste tre absorbsjonskolonner kan hvis det ønskes, forenes til én kolonne inneholdende de tre nevnte absorbsjonstrinn. The three absorption columns shown can, if desired, be combined into one column containing the three aforementioned absorption stages.
Claims (2)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE10296/64A SE332166B (en) | 1964-08-27 | 1964-08-27 |
Publications (1)
Publication Number | Publication Date |
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NO115736B true NO115736B (en) | 1968-11-25 |
Family
ID=20292073
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
NO159406A NO115736B (en) | 1964-08-27 | 1965-08-19 |
Country Status (9)
Country | Link |
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BE (1) | BE667312A (en) |
CH (1) | CH451901A (en) |
DE (1) | DE1253259B (en) |
ES (1) | ES315240A1 (en) |
FR (1) | FR1445868A (en) |
GB (1) | GB1110802A (en) |
NL (2) | NL6509215A (en) |
NO (1) | NO115736B (en) |
SE (1) | SE332166B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
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US3993702A (en) * | 1975-09-29 | 1976-11-23 | Phillips Petroleum Company | Production of unsaturated alcohols |
-
0
- NL NL131177D patent/NL131177C/xx active
-
1964
- 1964-08-27 SE SE10296/64A patent/SE332166B/xx unknown
-
1965
- 1965-06-30 CH CH916165A patent/CH451901A/en unknown
- 1965-07-05 DE DES97999A patent/DE1253259B/en active Pending
- 1965-07-12 ES ES0315240A patent/ES315240A1/en not_active Expired
- 1965-07-16 NL NL6509215A patent/NL6509215A/xx unknown
- 1965-07-23 BE BE667312D patent/BE667312A/xx unknown
- 1965-08-02 GB GB32960/65A patent/GB1110802A/en not_active Expired
- 1965-08-11 FR FR28042A patent/FR1445868A/en not_active Expired
- 1965-08-19 NO NO159406A patent/NO115736B/no unknown
Also Published As
Publication number | Publication date |
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NL131177C (en) | |
NL6509215A (en) | 1966-02-28 |
GB1110802A (en) | 1968-04-24 |
FR1445868A (en) | 1966-07-15 |
DE1253259B (en) | 1967-11-02 |
CH451901A (en) | 1968-05-15 |
SE332166B (en) | 1971-02-01 |
BE667312A (en) | 1965-11-16 |
ES315240A1 (en) | 1966-04-01 |
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