UNITED sratrnsrarnur UM ICE.

METHODIE JWANOWITSCH xusunzow. or oHARKow, RUSSIA, ASSIGNOR, BY MESNE ASSIGNMENTS, r'o PEB'IH kMBOY CHEMICAL WORKS, A CORPORATION 01 NEW Patented July 15, 11913.

JERSEY.

PROCESS FOR THE MANUFACTURE 01' FORMALDEHYDE.

1 067 665. Specification of Letters Patent.

No Drawing.

Application filed September 20, 19 9. Serial No. 518,612.

To all whom it may concern:

lie it known that I, Mu'rnoois JWANowrrscu Kvsnnzow, chemist, a subject of the lhupcror of Russia, residing at Charkow, Russia. have invented a certain new and useful Process for the llrlanut'acture of Formaldehyde, of which the following is a specification.

The usual process for producing formaldehyde consists in passing heated air through methyl alcohol and conducting the mixture of methyl alcohol vapors and air thus obtained over heated copper. Besides copper, platinum, pumice stone and other materials have been tried as catalyzers, but without success, on account of the interior yield obtained with these substances. I have found that metallic silver is a more advantageous catalyzer than copper and the other materials hitherto used.

The catalytic material is preferably pre pared from a sheet of fine-meshed silverwire netting by coiling it up into rolls or by piling up a considerable number of la yers of the same and compressing them, or by precipitating the silver from a solution of a silver salt, for instance, from an ammoniacal solution of silver nitrate and then applying it to a suitable non-catalytic base or support, such as asbestos-Wool, Woven asbestos-fabric or pumice-stone, which has been first relieved of organic substances by calcination. The catalytic material is introduced into the catalyzing apparatus of usual construction, after which the apparatus is strongly heated and the mixture of methylalcohol vapors and air is conducted over the catalytic material. As soon as the reaction has been started, the external heating of the catalyzer may be interrupted. The reaction mixture is now conducted continuously over the catalytic mass, care being taken, that the temperature of the apparatus will not drop too low (not below 250 C.) because otherwise the reaction would be interrupted unless heat be supplied from outside.

A small portion of the methyl alcohol passes undecomposed through the contact substance, but as the aqueous solution of formaldehyde formed in commerce always contains methyl alcohol, the reaction mixt ure produced may be utilized immediately.

The yield is almost equal to the theoretical quantity, which is not ossible in using copper as a catalyzer. I the latter is used, a tolerably good yield may be obtained only by conducting over the cat-alyzer also a large excess of methyl alcohol vapor, a portion of which remains undecomposed, but in that case the methyl alcohol must be separated from the reaction mixture by distillation, entailing expense and Waste of formaldehyde and methyl alcohol. This is at present the general standard of the art of making formaldehyde by oxidizing methyl alcohol by means of a copper catalyzer. Both the expenses for labor, etc., and the loss of raw material sustained in the various manipulations present considerable ditficulties and objections in commercial practice and render the control of the process very inconvenient, a tolerable yield only being obtained owing to over-oxidation, and hence, the general efiiciency of the copper contact process must be called a moderate one. Contrary to these shortcomings experienced in the commercial ractice of the old process, my invention a ords facilities which cannot be realized by the old process, most painstaking experiments under the various conditions having amply demonstrated that the highest and always reliable yield in formaldehyde loan only be attained by abandoning the present universally adopted copper catalyzer for the metallic silver catalyzer.

. In my process, it is immaterial to the yield, whether one runs the process with only a slight excess of methyl alcohol, or Whether one even operates with a gas mixture the constituents of which exist in practically theoretical proportions.

This fact is of vital importance to the industry of formaldehyde manufacture and represents a great advance, particularly in view of the above cited facts showing that the yield is almost theoretical and that the portion of methyl alcohol which escapes the reaction is so small as to render the reaction mixture immediately available for commercial purposes. The efi'iciency of my process of oxidizing methyl alcohol to formaldehyde by applying silver as a catalyzer is far suover heated metallic silver, substantially as 10 perior to that of any other process known at described. the present time, as the process may be so i In testimony gwhereof I have hereunto set well defined as to guarantee a very high and my hand in presence of'tw'o subscribing wituniform yield.

' lnesses. What I claim is:

METHODIE JWANOWIISCH KUSNEZOW. The proeess'for the manufacture of for- Witnesses: maldehyde, which consists in conducting a PAUL SOROLOFF, mixture of methyl aleohol vapors and air PETER Amuionorr.