US3420888A - Production of formaldehyde from trithiane - Google Patents

Production of formaldehyde from trithiane Download PDF

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Publication number
US3420888A
US3420888A US541512A US3420888DA US3420888A US 3420888 A US3420888 A US 3420888A US 541512 A US541512 A US 541512A US 3420888D A US3420888D A US 3420888DA US 3420888 A US3420888 A US 3420888A
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United States
Prior art keywords
trithiane
reaction
formaldehyde
cuo
air
Prior art date
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Expired - Lifetime
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US541512A
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English (en)
Inventor
Albert Schopf
Erhard Siggel
Gerhard Meyer
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Glanzstoff AG
Vereinigte Glanzstoff Fabriken AG
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Glanzstoff AG
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    • 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
    • C07C45/56—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds from heterocyclic compounds
    • C07C45/567—Preparation of compounds having >C = O groups bound only to carbon or hydrogen atoms; Preparation of chelates of such compounds from heterocyclic compounds with sulfur as the only hetero atom

Definitions

  • One object of the present invention is to provide a process for the production of formaldehyde from trithiane which can be carried out to obtain good yields in a relatively economical manner.
  • Another object of the invention is to provide a process for the regeneration of formaldehyde from trithiane initially obtained as a precipitate in the spinning bath used for the production of viscose rayon filaments.
  • Still another object of the invention is to provide a continuous method of converting trithiane into formaldehyde by reaction with substances which are relatively inexpensive and/ or easily regenerated for reuse in the process.
  • the copper-II-oxide is introduced for intimate contact with the trithiane in accordance with the invention as a finely divided or pulverulent material or else it can be precipitated or applied onto an inert carrier such as aluminum oxide. While the amount of the copper- II-oxide can vary over a broad range, e.g. in a weight ratio of CuO to trithiane of about 1:1 to 6:1, it is preferable to employ the copper-II-oxide in a slight excess over that which would be theoretically required if all of the oxygen in this copper-oxide were substituted for the sulfur of the trithiane. Thus, the preferred ratio by weight of CuO to trithiane is about 2:1 to 4:1. This ratio by weight is taken with reference to the initial materials since at least part of the CuO is converted into CuS during the course of the reaction. Although it would be possible to use a much larger excess of CuO, it will be apparent that this would not ordinarily be economical.
  • the reaction time is not critical, but it is dependent upon the reaction temperature and the extent to which the CuO and trithiane are brought into intimate contact with each other and with the oxygen-containing gas such as air.
  • the reaction proceeds most rapidly at higher temperatures and under conditions assuring the most intimate contact of the reactant materials. It is therefore preferable to work with a CuO-trithiane reaction mixture which is extended into a relatively thin layer of material in the reaction zone, e.g. by channeling the trithiane through a reaction zone packed with a carrier supported copper-II-oxide or by conducting an intimate mixture of the trithiane and copper-II-oxide in a relatively thin layer through the reaction zone.
  • relatively good results are also achieved without providing a small layer thickness and without thorough mixing.
  • reaction time at 230 C. can be reduced to a period of about two minutes.
  • the formaldehyde product can be obtained by the process according to the invention in yields of up to about 60%, with reference to the initial amount of trithiane induced into the reaction,
  • the copper-II-oxide and trithiane are initially mixed nad introduced into the reaction tube by means of a conventional feeding or dosing device, and the mixing of these materials is further promoted in the reaction tube by the screw conveyor.
  • the retention time of the reaction mixture can be regulated by controlling the number of revolutions of the worm or screw per unit time, i.e. by controlling the turning rate of the screw.
  • the air or other oxygen-containing gas can be introduced into the screw conveyor for passage therethrough, and the formaldehyde product is then separated with the stream of air at the outlet end of the reaction zone and condensed by cooling the effluent gas stream, e.g. in an air-cooled condenser.
  • both the copper-II-oxide and trithiane are carried concurrently with each other and it is also preferable to conduct the stream of air or other oxygen-containing gas in the same direction,
  • the carrier supported CuO can flow continuously in one direction through the reaction zone while the trithiane is carried by the stream of air or similar oxygen-containing gas in the opposite direction.
  • a CuO-CuS mixture is then removed from one end of the reaction zone and the formaldehyde is removed and condensed from the efliuent gas at the other end of the reaction zone.
  • the CuO-CuS mixture which is obtained after completion of the reaction can be very easily treated in order to regenerate CuO which can then be used again for further reaction with fresh trithiane.
  • This regenerating treatment is merely a simple roasting of a copper sulfide in the mixture so that it is converted by oxidation back into CuO.
  • This roasting can be carried out in situ after the reaction with trithiane is completed, or where the process is carried out continuously, the CuO-CuS mixture can be concurrently roasted in a separate continuous reaction stage and then recycled for use in the conversion of trithiane into formaldehyde.
  • the copper-II-oxide can be reused many times in this manner without any substantial reduction of the formaldehyde yield.
  • the roasting of the copper sulfide for conversion into copper-II-oxide is a very well known single step reaction which is relatively inexpensive and which permits one to avoid a multi-stage regeneration of a metal salt.
  • Example 1 5 grams of trithiane are finely ground with 10 grams of CuO and heated for a period of 2 hours in a 250 ml. two-necked flask while passing air through the flask at a temperature of l-200 C. The efliuent gas stream is passed through an attached cooling tube in which there are separated 1.47 grams of paraformaldehyde. This corresponds to a yield of 45%
  • Example 2 5 grams of trithiane are thoroughly mixed with 15 grams of CuO and heated for a period of one hour in a flask as in Example 1 with passage of air therethrough at 230 C. In the cooling tube, 1.65 grams of paraformaldehyde are separated, corresopnding to a yield of 51%.
  • Example 4 1 part by weight of trithiane is finely ground with 3 parts by weight of CuO and led into a reaction tube heated by indirect heat exchange to 230 C.
  • the reaction mixture is moved continuosly forward in the tube by means of a screw conveyor.
  • the number of revolutions of the screw is determined in such a manner that the average retention time of the reaction mass in the heated tube amounts to about two minutes.
  • a stream of air preheated to 230 C. is led into the tube for concurrent flow and contact with the reaction mixture.
  • the paraformaldehyde is removed with the air and is condensed and collected in an air cooler.
  • the yield amounts to 60% with reference to the initial trithiane.
  • COMPARATIVE EXAMPLE 1 part by weight of trithiane is intimately mixed with 2 parts by weight of Ag SO and 1 part by weight of CaO, and is conveyed with mixing through a reaction tube heated to 230 C. as described in Example 4.
  • the yield of paraformaldehyde amounts to 33 If one attempts to regenerate the Ag SO /CaO-mixture from the discharged solids in the same manner as described in Example 4, i.e. by a simple roasting step, then in the reutilization of the roasted product, there is obtained a yield of only about 3.6% formaldehyde.
  • the silver catalyst In order to achieve about the same yield of formaldehyde as described above, i.e. 33%, the silver catalyst must be converted back into Ag SO after thoroughly roasting the sulfur in known manner, i.e. by further treatment with sulfuric acid and evaporation.
  • the process of the present invention not only permits a substantial increase in the yield of formaldehyde but also avoids a costly and diflicult regeneration of the metal catalyst.
  • the formaldehyde product is obtained from the process in the form of a good commercial grade of paraformaldehyde and can therefore be used directly in the spinning bath for the production of viscose rayon filaments.
  • the process of the invention can be readily adapted to continuous operation, including the regeneration of the copper oxide from copper sulfide formed during the reaction.
  • the novel process of the invention is quite suitable for commercial exploitation, and variations or modifications of the process can be readily made by one skilled in this art without departing from the spirit or scope of the invention as claimed hereinbelow.
  • a process for the production of formaldehyde from trithiane which comprises contacting said trithiane with CuO and air at a temperature between about 190 C. and 250 C. and condensing formaldehyde from the efiluent gaseous reaction product.
  • a process as claimed in claim 1 wherein the ratio by weight of CuO to trithiane is about 1:1 to 6:1.
  • reaction zone is maintained at a temperature between about 210 C. and 230 C.
  • a process as claimed in claim 6 wherein the ratio by weight of CuO to trithiane in said mixture is about 2:1 to 4: 1.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US541512A 1965-04-23 1966-04-11 Production of formaldehyde from trithiane Expired - Lifetime US3420888A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DEV28311A DE1220844B (de) 1965-04-23 1965-04-23 Verfahren zur Herstellung von Formaldehyd durch katalytische Oxydation von Trithian

Publications (1)

Publication Number Publication Date
US3420888A true US3420888A (en) 1969-01-07

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ID=7584044

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US541512A Expired - Lifetime US3420888A (en) 1965-04-23 1966-04-11 Production of formaldehyde from trithiane

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US (1) US3420888A (enrdf_load_stackoverflow)
BE (1) BE678211A (enrdf_load_stackoverflow)
DE (1) DE1220844B (enrdf_load_stackoverflow)

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
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Also Published As

Publication number Publication date
BE678211A (enrdf_load_stackoverflow) 1966-09-22
DE1220844B (de) 1966-07-14

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