US2197257A - Hydrocarbon synthesis - Google Patents

Description

Patented Apr. 16, 1940 maocamson SYNTHESIS Robert a. Burk, Cleveland, Ohio, assignor to The Standard Oil Company (Ohio), Cleveland, Ohio,

a corpoh'ation of Ohio No Drawing. Application July 14, 1938, Serial No. 90,567

4Claims. (cram-cs)- olefine production from a mixture of gases of the ethylene and acetylene series, 15 portant measure upon dilution by presence of diluent gases or the like. I have found that in commerciable synthesizing of-hydrocarbons it is important to operate with raw materials and conditions of definite and certain character as depending in im- 20 contradistinguished from averages, and ,with,

avoidance of diluents, over-run of reaction being controlled against. By the present invention thus, it becomes possible to operate with production of definitely controllable products and 25 with elimination of excessive wastes and losses which have been customary.

7 To the accomplishment of the foregoing and related ends, the invention, then, comprises the. features hereinafter fully described, and partic- 30 ularly pointed out in the claims, thev following description setting forth in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the invention may 35 be employ The materials for the present synthesis are on the one hand acetylene, and on the other hand hydrocarbons of gasiform character, as detailed subsequently. The acetylene is prepared in a suitable manner, for instance by thermolytic ac-.- tion in an electric are or electric furnace from methane or at least gas which is predominant inmethane, or preferably by the cracking of selected hydrocarbons. Thus, yields of acetylene by cracking hydrocarbons at temperature higher than the. conventional cracking temperatures have been mentioned in the art, e. g. U. S. Patent No. 1,962,502, and as reported by Tropsch, Parrish and Egloii, Ind. Eng. Chem. 28: 501, yields of acetylene by cracking ethylene at 1400 C., and somewhat poorer yields by cracking propylene at the same temperature. Contrary to the opinion expressed found that operating with ethylene, desirable 55 yieldsof acetylene maybe obtained therefrom in current literature however, I have I at a much lower temperature range than 1400" C., as for instance down to about 600 C., and particularlyfavorably around 700 C. And, with the acetylene there is obtained an advantageous yield of olefins. Thus, ethylene, or for that matter 5 hydrocarbons higher than methane, or from two carbon atoms up, including those normally in liquid fractions such as kerosene, gas oil etc., maybe so treated, heating at the noted moderate temperature range rather than the high temper- 10 ature range customary heretofore, and desirably with the presence of a diluting gas, for instance steam, and after separating the acetylene from the product mixture, for instance conveniently by solvent extraction with a ketone, as acetone, etc., and separating the hydrogen, as for instance by suitable cooling or fractional condensation of the hydrocarbons whereby the hydrogen maybe eliminated, there is thus available acetylene, also ethylene, and some higher molecular weight hydrocarbons. In such cracking, the time of heating is a few seconds, for instance 2-8, depending somewhat upon the particular hydrocarbons. With suitably selected raw gas material, the. entire synthesis including the prepara- 5 tion of'the acetylene and the reaction between the acetylene and the other hydrocarbons can be carried through from one consistent standpoint. A gas of methane content tofabove 96 percent is readily obtainable from natural gas sources, or from certain refinery gases. In fact,

in favorable situations, refinery gas sources are able to supply such gas as is desired of high methane contentyand on the other hand other gas which is of hydrocarbons from ethane and up, short of the condensible or absorbable hydrocarbons, or in other words a gas comprising hydrocarbons in the range of 2-4 carbon atoms.

Furthermorathere is a distinction possible as between saturated and unsaturated hydrocarbon sources in this range. For the process then, a methane-rich gas may be passed through a furnace, and with temperatures higher than 1500 C., acetylene is formed from the methane, together with free hydrogen. The yield of acetylene here is in general, as known, higher, the higher the temperature and the greater the dilution, or the. lower the pressure, Ind. Eng. Chem. 26: 56. The detail of suitable furnaces is not important, and

it is sufiicient to herestate that the gas stream may be fed directly through the path of a. suitable are, or the heating zone may be somewhat more extensive in that the electrodes are employed in conjunction with granulated carbon used as a resistance furnace, the methane being forcedtherethrough at a rate keeping the passageways clear.

is formed, and before it has opportunity to drop in temperature sufiiciently to polymerize, my procedure provides for its shock-cooling, and while this may be effected more or less mechanically as by molten lead through which and with which the hot stream is contacted, a more efficient action is had by commixing selected hydrocarbons with the hot acetylene stream,;andthereby the shock-cooling and prevention of losses of acetyarate hydrogen, then pass the acetylene and other hydrocarbons for reaction therewith, tnrough a heating zone controlled to temperature for the particular products in view. Taking a refinery gas source for instance providing propylene and butylene, the butylene tends to combine with the acetylene-in order first, and then the propylene, with respect to speed. Propylene plus acetylene forms isoprene,'which is available for various syntheses, including rubber and rubber-like products.

By employing such gases or gas fractions as are ofsaturated character, as ethane, propane, butane, products free from the dioleflnic type foregoing, are-obt'ained viz. for'instance butene, pen

tene, hexene, etc. on reaction with acetylene.

In general, the selected hydrocarbons which are tobe reacted with the acetylene, or the closelyranged hydrocarbon gases are brought into reaction with substantial absence of diluents although the contrary may be practiced. Catalysts are not always of advantage. In some instances'for certain products-,a catalyst is of advantage, and

for this I prefer catalysts containing copper or certain halides. Pressure of high order is-not necessary, and in fact it is preferable to operate at atmospheric pressure. or at least not substantially in excess of 500 pounds per square. inch.

Immediately as the reaction between the acetylene and the other hydrocarbon component isaccomplished, the formed products are stripped out from the reaction mass, this being accomplished in a suitableway, depending upon the precise character of the end products being made.

Thus, normally gaseous unsaturated products" Hydrogen may be recycled for the latter purpose. Immediately as the acetylene may be taken out by suitably cooling andpassing the gaseous mixture through selective oil-absorp-' tion. columns. Condensible products such as pentene may be taken by passing through a condensation zone.- .If operating by saturated gas components together with acetylene and forming pentene in mixture with higher hydrocarbons as hexene and heptene, all of the condensible portion may in some instances be desired to be'taken out en masse, as available for special usages in lightening or blending motor fuels. 7

' The olefines produced conjointly with the acetylene may be polymerized separately, or be caused to react with acetylene or to'react with paraflins.

-The olefines formed by reaction of acetylene with paraflins similarly may be handled in these several ways.

' Other modes of applying the principle of the invention may be employed, change-being made as regardsthe details described, provided the features stated in any of the following claims, or the equivalent of such, be employed;

I therefore particularly point out and distinctly claim as my invention:

1. Hydrocarbon synthesis, comprising acetylenizing methane in a furnace zone, shock-cool- .ing the acetylene before polymerization substantially occurs by admixing therewith an aliphatic hydrocarbon of 2-4 carbon atoms and in amount reducing the temperature of the mixture to intercombining temperature, and separating the formed hydrocarbons.

2. Hydrocarbon synthesis, comprising acetylenizing methane in a furnace zone, shock-cooling the acetylene before polymerization substam tially occurs by admixing propylene therewith and in amounts reducing the temperature of the mixture to inter-combining temperature, and

separating the so-formed diolefine.

3. Hydrocarbon synthesis, comprising acetylenizing' methane in a furnace zone, shock-cooling the acetylene before polymerization substantially occurs by admixing therewith unsaturated hydrocarbons of 2-4 carbon atoms and in amounts reducing. the temperature of the mixture to inter-combining temperature, and separating .the formed hydrocarbons.

4. Hydrocarbon synthesis comprising acetylenizing methane in a furnace zone, shock-cooling the acetylene before polymerization substan- .tially occurs by admixing therewith saturated hydrocarbons of '2-4 carbon atoms and in amounts reducing the'temperature of the mixture to'inter-combining temperature, .and condensing out the formed hydrocarbon products.

ROBERT E. BURK.