US2002534A - Method for the production of normally liquid hydrocarbons from gaseous or lower boiling hydrocarbon materials - Google Patents

Description

Patented May 28, 1935 UNITED STATES METHOD FOR THE PRODUCTION OF NOR MALLY LIQUID HYDROCARBONS FROM GASEOUS OR LOWER BOILING HYDRO- CARBON MATERIALS Per K. Frolich, Elizabeth, N. J., assignor to Standard Oll Development Company No Drawing.

Application September 10, 1930,

Serial No. 481,070

.10 Claims.

The present invention relates to an improved method for the production of normally liquid hydrocarbons from gaseous or lower boiling hydrocarbon materials and more specifically to a process for the production of liquid hydrocarbons boiling within the range suitable for commercial gasoline from gaseous or low boiling hydrocarbons. My process will be fully understood from the following description.

In a prior application Ser. No. 438,650 filed March 24, 1930 now Patent No. 1,869,681 the present inventor disclosed an advantageous process for the manufacture of low boiling materials liquid at normal temperatures and pressures from normally gaseous hydrocarbons such as ethane, propane, butane and the like which occur in large volume in natural or refinery gases. These materials are used at the present time as fuel due to the fact that the hydrocarbons are normally gaseous or boiling at too low a temperature to be included in commercial gasolines. The present application is an improvement over the process disclosed in my prior application above noted for accomplishing the same purpose with greater ease and economic advantage.

My process consists in a series of steps as follows: First the conversion of saturated materials such as ethane, propane and butane into olefins, which is accompanied by the liberation of free hydrogen. The second step comprises removal from this gaseous mixture of the free hydrogen and the third step comprises polymerization of hydrogen-free gas to form normally liquid hydrocarbons suitable for commercial motor fuel. Each of the said steps will be separately described. The first, or cracking step may be carried out in any desired manner, for example; merely by heating to a decomposition temperature say from approximately 500 to 1000 C. either with or without pressure and in the presence or absence of catalysts, preferably used in non-ferrous tubes or ferrous metal tubes containing 8% of chromium or more. The preferred method, however, is that disclosed in the copending application Ser. No. 360,000 of the present inventor with B. O. Boeckeler which was filed May 2, 1929. This process comprises dehydrogenation of hydrocarbons by the use of certain catalytic agents at temperatures within the approximate range of 450 C. to 700 C. with or without pressure (up to 250 lbs. per square inch). Metallic catalysts have been found satisfactory and the mixture of metallic oxides after reduction with methanol, hydrogen or hydrocarbon vapors or otherwise, are preferred although other types of dehydrogenation catalysts may be used. Catalysts containing zinc and another metal which has two or more valences are particularly desirable, such as 30 mol. percent zinc, '70 mol. percent of chromium or other proportions of the same elements, or zinc and molybdenum or tungsten, vanadium and the like. The rate of flow of the gases in this process is preferably very rapid, for example; above about two volumes of hydrocarbon vapor per minute per volume of reaction space and under such conditions it is observed that two or more atoms of hydrogen are removed from the hydrocarbon molecule with substantially no decomposition of the carbon structure, that is to say, substantially no hydrocarbons of fewer carbon atoms are produced.

This process may be used on pure hydrocarbons or mixtures of two or more hydrocarbons and diluent gases including hydrogen, nitrogen, methane or other gases may be used. In this way the highest yield of olefins and consequently the lowest yield of methane which forms as a waste product in the process is obtained.

The gas obtained from the first step of my process comprises a mixture of olefins, unreacted paraflinic hydrocarbons and hydrogen. Removal of the major quantity of the free hydrogen comprises the, second step and this is accomplished in a particularly desirable manner by the addition of carbon monoxide, carbon dioxide or a suitable mixture of the two materials either alone or with other substances acting as diluents such as nitrogen, steam and the like. The gas mixture is passed over a suitable catalyst such as will be disclosed below by which free hydrogen is converted into methane by reaction with the oxides of carbon.

In the operation of the hydrogen removal step I have found that the reaction operates successfully either at atmospheric or at higher pressures, but preferably it is carried out under pressures of several atmospheres and may be carried out at considerable pressures of 100 atmospheres or more. The catalysts most suitable for my process are methanizing catalysts and consist of metallic nickel or of nickel oxide in finely divided form, but it is desirable to add additional agents such as aluminum oxide, thoria or other rare earths, chromium, vanadium, tungsten, molybdenum, manganese, boron and similar oxides preferably in amounts less than the nickel or its oxides. The temperature is preferably below 400 C. and operates satisfactorily within a range from about 200 to 350 C. When carried out on a small scale there is no difficulty in keeping the apparatus cool as the radiation loss is generally sufiicient for the purpose, but when large tubes are used and relatively large volumes of gas are treated it is desirable to provide some method of cooling so as to prevent an excessive rise in temperature. It is desirable also to desulphurize the gas and this step may be accomplished either after the cracking operation or before such an operation,-as will be understood. Any desirable means of desulphurization may be used, for example a gas may be washed with soda solution or mixture of sodium carbonate containing iron oxide. 3 v

The third or polymerization step may be carried out under atmospheric pressure or at higher pressure, for example above 100 pounds per square inch, but preferably in the range from 300'to 1000 pounds per square inch. The temperature may vary considerably within the approximate limits of 500 to 900 C. and it has been found that. with higher pressure it is generally desirable to use somewhat lower temperatures. The time of reaction may vary widely, for example, from less than 1 minute at higher temperatures to 25 or minutes orlonger at lower temperatures and contact materials may be used, preferably of a metallic character having a high heat conductivity in order to maintain uniform temperatures throughout the reaction chamber.

Using the present process, comprising the three steps described above, yields of l to 8 gallons or more of liquid products may be obtained per thousand cubic feet of propane orv gases comprising, ethane, propane and butane. One

- half or more of the'distillate is generally sumcientlv low boiling for commercial gasoline and is ordinarily admirably suited for use in internal combustionengines by reason of its anti-detonation qualities. It may be used alone or may be blended with other materials available in petroleum refineries. The higher boiling material is sometimes of a tarry nature. 1

As an example of the operation of my process propane is passed through a tube of copper or other metal such as chrome steel or ceramic material heated to a temperature of about 800 C. The outgoing gas has the following composition:

Percent (111'- 13 0on1 Ha 30 CH4+CaHc 31 This gaseous mixture is then mixed with about 15% of its volume of carbon monoxide producing a ratio of about 2 mols of free hydrogen per moi. of carbon monoxide and after mixing this gas is passed through a soda solution to remove sulphur compounds.- The mixture is now compressed to a pressure of about 600 pounds per square inch and passed through a chamber preferably in the form of tubes fllled with a catalyst comprising a mixture of about 70% of nickel bxide and 30% of aluminum oxide. The temrature is maintained at about 300 C. and the rate of flow is adjusted to give a substantial removal of hydrogen. The eiliuent gas has the following analysis on a dry basis.

Percent (11H: 15.4 Cal-T4 30. 6 CH4+C2H 52-54 H 1 Below about 2 This mixture is now passed at a rate adjusted liquid product shows that about thereoi boils within the range of 85 to 220 C. the mixture is highly unsaturated and with the bromine number over 100. It is light in color. After finishing at ordinary methods known in the petroleum industry and cut to a final boiling point of about 200 C. it is admirably adapted as an anti-detonating fuel for internal combustion engines, it being equivalent in antidetonating value to a naphtha from an ordinary sweet'crude such as mid-continent crude to which at least 80% of benzol has been added.

As has been indicated above carbon dioxide may be used in the process in place of carbon monoxide as described in the previous examples.

With pressure a smaller excess may be used.

It is preferable to use CO for this purpose because it is readily combustible and the resulting mixture of methane and excess CO may be used,

as a source of fuel for preheating the raw gases and keeping the reactors up to temperature.

The entire series of steps may be carried out at atmospheric or higher pressures, say

pounds per square inch or if desired, one or more steps may be at low pressure, while the other or others are accomplished at higher pressure. It is particularly desirable to conduct the cracking steps at atmospheric pressure or below 100 pounds, scrub with alkali to remove sulphur, remove free hydrogen at the same pressure and subsequently polymerize at pressures above 100 pounds. Y

My invention is not to be limited by any theory of the mechanism of the reactions nor to any specific example which may have been given for purpose of illustration, but only by the 101- lowing claims in which I wish to claim all novelty inherent in my invention.

1 claim:

1. An improved process for obtaining valuable higher boiling hydrocarbons from gases containing large amounts of lower boiling saturated hydrocarbons containing more thanone carbon atom which comprises cracking the lower boiling materials whereby a substantial proportion of unsaturates is formed together with free hydrogen, subsequently adding to the mixture a gas rich in an oxide of carbon, causing the oxide of carbon and hydrogen to react and then poiymerizing the unsaturated hydrocarbons.

2. An improved method for converting low molecular weight parafiln hydrocarbons containing more than one carbon atom to higher molecular weight hydrocarbons which comprises the steps of converting the parafilns to oleflns and hydrogen by the action of heat, removing free hydrogen by reaction thereof with carbon monoxide and then polymerizing the hydrogen free mixture.

3. An improved process for converting low molecular weight saturated hydrocarbons containing more than one carbon atom into higher molecular weight hydrocarbons comprising first converting saturated hydrocarbons into oleflns by action of heat at temperatures above about 450 8. An improved process for obtaining valuable higher boiling hydrocarbons from lower boiling 0. and below about C. then mixing a gas rich in carbon monoxide therewith to provide an excess of CO over the ratio of 1 CO to 2 H: and passing the mixture over a methanizing catalyst at temperatures within the limits of about 200 to 400 0. whereby the hydrogen content of the gas mixture is reduced to below about 2% and poly-1 merizing the remaining olefins at temperatures within the appropriate limits of 500-900' C,

4. Process according to claim 1 in which the hydrogen in the gases is substantially completely removed.

5. Process according to claim 1 in which a methanization catalyst comprising a major proportion of nickel is used to cause reaction 01' the oxide of carbon with hydrogen.

6. Process according to claim I in which conversion of saturated to olefin hydrocarbons is carried out at pressures below 250 lbs. per square inch the dehydrogenation at pressures between the approximate limits of several atmospheres and 100 atmospheres, and the polymerization at pressures between the approximate limits of 300 to 1000 lbs. per sq. in.

'7. Process according to claim 1 in which the gases resulting from the first step of the process are desulphurized before the hydrogen removal step.

and gaseous saturated hydrocarbons containing more than 1 carbon atom comprising converting the saturated into olefin hydrocarbons by the action of heat at temperatures above about 500 C. and below about 1000' C. at pressures below about 250 pounds per square inch, passing the gas mixture througha suitable desulphurizing agent, compressing the purified gas to pressure between about 300 and 1000 pounds per square inch, mixing carbon monoxide therewith in proportion required to provide a substantial removal of hydrogen, passing the mixture over a methanization catalyst at temperature of 200.- to 350 C. and then polymerizing the remaining olefins at temperatures above 500 C. and below 900 C. n

9. Process according to claim 1, in which th cracking step is carried out at temperature between the approximate limits at 500 to 1000 C. in the presence of a catalyst consisting of zinc and a metal element of the sixth group having two or more valences. I

10. Process according to claim 1, in which petroleum refinery gases are used as a raw material.

PER K. FROLICH.