SU947158A1 - Process for producing formaldehyde - Google Patents

Description

(54) METHOD FOR OBTAINING FORMALDEHYDE

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The invention relates to methods for producing formaldehyde, which is an important raw material in the preparation of aldehyde resins and polymers.

There is a method of obtaining formaldehyde from methanol at high temperatures on a silver catalyst, and the following reactions occur:

СРЦОН + 1/2 О,

+ H, 0 + + 36.8 kcal / mol.

 , 8 kcal / mol

In addition, as a side process, reactions of the pyrolytic decomposition of formaldehyde and its further oxidation occur, leading to the formation of undesirable impurities that deactivate the catalyst.

It is known that the presence in the reaction mixture of organic impurities inhibits the reaction of formaldehyde formation. Thus, impurities of aldeptd and ketones, amines, iron pentacarbonyl, eftf contained in

methanol, disrupt the oxidation process and poison the catalyst.

The known method noJV4eHHH formaldehyde using wastewater productions .a for the processing of formaldehyde 2.

However, the use of wastewater in the production of formaldehyde is limited due to the fact that most of the organic impurities that they contain have an adverse effect on the formaldehyde formation process.

The closest to the proposed technical essence and the achieved result is a method for producing formaldehyde, which includes a mixture of methanol with wastewater containing; methanol and formaldehyde.

According to the limestone method, it is possible to dispose of wastewater from the production of formaldehyde or carbamide resins, i.e. such waters, which besides methanol and Bt. The dyes contain no more than 3.5% formaldehyde.

An issative method is that in the raw material product a mixture of methanol and production waste containing methanol, formaldehyde is taken, and this mixture is oxidized with oxygen of nt 65 O-700 C. The yield of formaldehyde is 7 O% C 3,

The disadvantage of this method is that only wastewater containing methanol, water and not more than 5% formaldehyde is recycled. However, when using 37% formalin in a series of productions, for example, in the preparation of copolymers and formaldehyde polymers, waste containing not only methanol and water up to 8% dimethyl ether and significantly larger amounts of forgolddehyde 2 O-4O% are obtained. Their further use is usually associated with additional costs for rectification, thermal neutralization, neutralization, dilution / treatment and biochemical purification. Often the cleaning processes are so complicated and expensive that these solutions simply burn,

The purpose of the invention is to increase the yield of formaldehyde.

The goal is achieved by the fact that in a process involving mixing methanol with wastewater containing methanol and formaldehyde, methanol mixes methanol with wastewater with an additional 1: 0 methanol: wastewater ratio in the silver catalyst at suspended temperatures 4-1,42,

The treatment is preferably carried out at еоО-75 (and, as a feedstock, use wastewater containing,%:

Methanol1-9O

Formaldehyde 0.1-45

Dimethyl ether 0.1-8 The proposed method is carried out as follows.

Waste water of a certain composition is mixed with methanol, the resulting mixture

evaporated at 70-8 ° C, then the resulting vapor-gas mixture was oxidized on a silver catalyst at a random temperature. The reaction products are isolated according to known methods.

The proposed method, utilizing wastewater containing, in addition to water, methanol, aldehydes and ethers, allows to increase the yield of formaldehyde not only due to the disposal of industrial waste, but also due to the activation of the formation of the target product,

Example: To evaporate the right 70 ° C, a mixture of methanol in the amount of 2382 kg / h and wastewater in the amount of 180O kg / h and containing 46% water (828 kg / h), 45% formaldehyde (810 kg / h), 8% dimethyl ether (144 kg / h), 1% methanol (18 kg / h). The ratio of methanol: waste water 1.32. The vapor-gas mixture is fed to a silver catalyst, where 3,428.57 air enters when the initial mixture is oxidized. The content of dimethyl ether in the initial mixture of methanol and wastewater is 3.84%. After absorption, 1850 kg / h of 00% -41th formaldehyde are obtained. After deducting formulated in the initial mixture, formaldehyde yield on the missed methanol is 77.1%, and reacted 88.1%. The yield from the theory is 32.22%, and the selectivity is 94%. Composition of gases after absorption, vol.%: COj. 3.4; CO 2.8; Н2.20,1; , 2} nitrogen 73,5. Under the conditions of the example, the process is carried out at different ratios of methanol: wastewater.

The results obtained are presented in the table.

Thus, the proposed method allows to increase the yield of formaldehyde in comparison with the known method while simultaneously disposing of waste processes of formaldehyde.

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Claims (3)

Invention Formula I. A method of producing formaldehyde, comprising mixing methanol with wastewater, containing meginol and formalderD, and treating at silver temperatures on a silver catalyst, characterized in that, in order to increase the yield of formaldehyde, methanol is mixed with wastewater containing additionally dimethyl ether in a ratio methanol: wastewater 1U, 4-1,42. 2. The method according to p. I, about tl and h and y -. u and with the fact that the processing on the silver catalyst is carried out at 6OO-75O C. 1588 3. The method according to tin I and 2, that is, with the fact that the waste water is sootat,%: methanol 1-9О, formaldehyde 0.145 and dimethyl ether 0.1-8. 5Sources of information taken into account in the examination. 1. Starlings S, O. Formalin and urotropin production. M-PE, Goslestekhizdat., 1947, p. 32-33. 10 2. Yakovenko 3. I. et al. Effects of mixtures in methanol on the process of catalytic oxidation of it on a racetrack. to the lysator, ZhFH, 52,4,1978, with. 1O54. 3. Author svidete; Soviet USSR 15 No. 368222, cl. C 07 C 47 / O4, 197O (prototype).