US2215474A - Oxidation of hydrocarbons - Google Patents

Description

jzqdracarbom and/416019011,

Sept. 24} 1940. w. KING ET AL 2,215,474

' OXIDATION OF HYDRQCARBQN;

Origin'al Filed April 2. 193a I 5 w ke/ wafer de/z'ga'er azzdAcidr Willazzz fiz/f 122g v 1 Cl 6 266 y INVENTORS g BY ATTORNEY Patented Sept. 24, 1940 UNITED STATES OXIDATION OF HYDROCARBONS I William 11. King, New Orleans, La., and Clyde Q. Sheely, State College, Miss.

Original application April 2, 1938, Serial No. 199,636. Divided and this application July 26,

1939, Serial No. 286,616

, 1 Claim.

This invention relates to a new and improved process for the preparation of chemical compounds by the oxidation of aliphatic hydrocarbons in the presence of a catalyst, and more particu- 5 larly to such a process wherein the reaction products comprise aliphatic alcohols, aldehydes and acids.

This application is a continuation-in-part of our copending application Serial No. 108,478, filed October 30, 1936, and is a division of our copending application Serial No. 199,636, filed April 2, 1938.

The higher aldehydes of the aliphatic series have considerable value as chemical compounds and a number of them have found use in industry 16 as perfumes. The difiiculties in the way of preparing such compounds, however, have kept their costs so high as to limit their field of usefulness. An improved and simpler method of obtaining such aldehydes would make more accessible a very m desirable class of products. The same condition holds in the case of a number of the higher aliphatic alcohols and acids also, for example those containing in the neighborhood of 8 to 12 carbon atoms.

25 An object of our invention is an improved method for the production of alcohols, aldehydes, and acids by the incomplete oxidation of aliphatic hydrocarbons. A further object is such a process in which carefully controlled conditions allow a 30 high degree of efiiciency in the preparation of .the

desired products. A still further object is a process in which the several products obtained may be separated in relatively pure form. Additional objects will be disclosed as the process is further 35 described hereinafter.

We have found that the foregoing objects may be accomplished by the process of our invention which comprises introducing a normally liquid hydrocarbon in the vapor phase into a heated o chamber, together with an oxidizing agent comprising a gas containing free oxygen. The oxida tion step is carried out in the presence of nitrobenzene as a catalyst. Withinthe reaction chamber the mixed gases and vapors are subjected to 5 a temperature between 250 and 500 C. while the oxidation of the hydrocarbons constitutes an exothermic reaction, the heat evolved will not be sumcient to maintain the desired temperature and external heating will be necessary. It is essential 60 that the reaction period be kept at a relatively short time interval, and we have found '15 seconds to be the maximum allowable time. Preferably we employ a reaction periodnot greater than 12 seconds, in orderthat the oxidation may not pro- 55 ceed too far. The reacting materials and reaction products are removed from the heated chamber while still in the vapor phase and are condensed by any desired method and apparatus under such conditions and in such an atmosphere that further reaction cannot take place. The amount of hydrocarbon will be above the explosive limit in all cases. W have found it desirable to use an amount of hydrocarbon 'of at least 10% by volume of the gaseous reaction mixture, and preferably between 20 and 40%. 10 It will be a desirable step in our process also to utilize the unreacted hydrocarbon resulting from the process and to recycle it to an additional similar oxidation step, whereby the advantages of the presence of an excess of hydrocarbon are obtained 15 with no loss in non-reacting material.

The accompanying drawing shows diagrammatically a flow sheet of one method of carrying out our process. From a reservoir l, the normally liquid hydrocarbon is forced through conduit 2 into the preheater 3. The gas containing free oxygen is passed through conduit 4 through the preheater 3, en route to the reaction chamber 5. Both the vaporized hydrocarbon and the oxygen containing gas pass into the reaction chamber 5 where they become intimately mixed and where a temperature of 250 to 500 C. is maintained, .said catalyst, promoting partial oxidation, being present, whereby partial oxidation of the hydrocarbons is brought about. The vapors pass out the conduit 6 into separator I, where any tar formed in the process is separated out. The mixed vapors and gases then pass through con-. denser 8, where the products capable of condensation become liquefied. The liquid condensate flows into reservoir 9, while a second vessel l0 receives any further condensed product not caught in chamber 9, but condensed in -l I. The reservoirs 9 and I0 contain the liquefied unreacted hydrocarbon that has passed through the process, and 0 also condensed water and the alcohols, aldehydes and acids resulting from the oxidation process. Such alcohols, aldehydes and acids will commonly be found in the water-insoluble layer.

Specific operating conditions suitable for our process for the production of alcohols, aldehydes, and acids are shown in the following example. This is to be considered as merely illustrative, however, and not limiting in its application Example 5 cc. of nitrobenzene was dissolved in 200 cc. of naphtha. This mixture was vaporized in the usual manner and mixed with 'air at a temperature of 387 C. The timecof reaction was 5.255

seconds and the percentage of hydrocarbon in the reaction mixture was 18.7. The yield w 16.84% aldehydes and 14.15% acids.

The method of operation according to the present invention produces alcohols. aldehydes and acids. However, it isespecially favorable to the production of alcohols.

The alcohols, aldehydes and acids resulting from the oxidation of hydrocarbons according to the process of our invention, are products of considerable economic value and of desirable properties, and the process described offers a novel and advantageous method of obtaining such products. Our process is characterized by higher yields and greater eiliciency than any process in the art.

The alcohols, aldehydes and acids may be separated from the hydrocarbon condensate and from one another by the use of suitable solvents. In

the case of aldehydes, for example, a saturated solution of sodium bisulfite was found desirable for extraction, the bisulfite subsequently being made alkaline and being subjected to steam distillation. The acids were desirably extracted by means of sodium hydroxide solution. The alcohols are preferably extracted by means of phosphoric' acid.

While our process has been described in detail in the foregoing, it will be understood that many variations in procedure may be employed without departing from the scope of our invention. In the example cited, a hydrocarbon fraction of a specific distillation range was used, but it would be a highly desirable procedure also to.start with a singlealiphatic hydrocarbon, ior example octane, or a mixture of octanes.

We wish to be limited, therefore, only by the following patent claim.

.We claim:

'The process for producing partially oxidized products of normally liquid aliphatic hydrocarbons which comprises introducing said hydrocarbons in vapor phase, together with an oxidizing agent comprising a gas containing free oxygen, into a reaction chamber at a temperature betwen 250 C. and 500 C., and reacting said materials for a period not exceeding 15 seconds in the presence of nitrobenzene.

WILLIAM H. KING. CLYDE Q. SHEELY.

Images