2,408,970 Patented Oct. 8, 1946 UNITED STATES PATENT OFFICE 2,408,970 BUTADIENE PURIFICATION Thomas F. Doumani, Long Beach, and Davis A. Skinner, Compton, Calif., assignors to Union Oil Company of California, Los Angeles, Calif., a corporation of California No Drawing. Application December 16, 1943, Serial No. 514,546 5 Claims. (Cl. 260-6815) 1 This inventionrelates to the production of butadiene, and especially to a method for puri? cation of hydrocarbon mixtures containing buta~ diene and acetylene type hydrocarbons of the same boiling range, whereby the acetylenes are removed by a selective hydration process, with out appreciable effect on the butadiene. Butadiene has attained vital importance in recent years as an ingredient of synthetic rub her, and as a raw material for many other uses. For many of these uses, such as in synthetic rub ber manufacture, it is necessary or at least high ly desirable that the butadiene be free from con tamination with other, hydrocarbons, particular 2 the acetylenes are selectively converted to oxy gen-containing compounds, While the butadiene or other unsaturated hydrocarbons are substan tially unaffected. The oxygen-containing com pounds are then separated from the unreacted unsaturated hydrocarbons by conventional methods such as distillation, solvent extraction, azeotropic distillation, or the like. As a speci?c example of our invention, the fol~ lowing process was carried out: A naphthenic California crude gasoline frac tion was cracked by vaporizing it and contacting the vapors with hot ?ue gases at substantially atmospheric pressure under such conditions that 1y acetylenic hydrocarbons. Since butadiene pro 15 an average temperature of about 1500° F. was maintained for a period of about 0.02' second. duced by pyrolysis of other organic compounds, The C4 fraction recovered from the product by particularly hydrocarbon mixtures such as pe absorption and distillation contained about 54% troleum fractions, generally contains large butadiene, 5% acetylenes (largely vinyl acetylene, amounts of such contaminating hydrocarbons, the puri?cation of butadiene presents a serious 20 but also methyl and ethyl acetylenes), 3% bu tanes, and the remaining approximately 38% bu problem, and many processes have been devised tenes, all per cents being molal. as attempts to solve it. In most of these proc The above C4 fraction was passed through a esses, distillation is the ?rst step; but by this tube containing 100 ml. of catalyst at a rate of 4 means, unless elaborate super~fractionation is liters (atmospheric temperature and pressure) employed, the product obtained is a so-called C4 per hour, together with Water vapor introduced out, which contains in addition to butadiene, other hydrocarbons or azeotropic mixtures which boil in the same range, including isobutane, normal bu-= at a rate of 25 grams per hour. The temperature of the catalyst bed was held at 300° C., and the total pressure was substantially atmospheric. tane, isobutene, the normal butenes, and methyl, ethyl, and vinyl acetylenes. Azeotropic distilla 30 The product gas after removal by condensation of substantially all of its oxygenated organic tion, extractive distillation, and solvent extraction compounds and water, was found to contain less than about 0.01% of acetylenes, while the buta diene ‘and other unsaturated hydrocarbons (bu preciable proportion of them, remain with the 35 tenes) were substantially unaffected. The bulk processes have been employed to separate the hu tanes, and even the butenes from this mixture, but in general the acetylenes, or at least an ap butadiene, since their chemical characteristics are quite similar, We have now discovered a method whereby acetylenes in mixtures with butadiene may be of the oxygenated organic compounds produced by the reaction of the acetylenes with the water Were recovered as an oily upper layer in the liquid condensate, although a small amount dissolved quantitatively removed without appreciable loss 40 in the lower aqueous layer of condensate. The oily upper layer contained a small amount of hy of butadiene. This method not only effects puri drocarbons, apparently dimer and higher poly ?cation of the butadiene but also converts the mers of butadiene, but was predominantly com acetylenes removed to by-products of great value posed of oxygenated compounds, principally al as solvents, perfumes, chemicals, etc. It is an object of our invention therefore, to provide a 45 dehydes and ketones, including methyl vinyl ke tone, methyl ethyl ketone, acetone, crotonalde method for separating acetylenes from butadiene. Further objects are to provide methods for sep arating acetylenes from other diole?ns or from hycle, butyraldehyde and propionaldehyde. The catalyst employed in the above example other unsaturated hydrocarbons such as mono was a 12 to 20 mesh siliceous solid phosphoric a hydrocarbon mixture containing acetylenes and Company of Chicago, Illinois. ole?ns and for converting acetylenes to valuable 50 acid commercially available as a polymerization catalyst. It is known as Polymer Catalyst No 2, aldehydes, ketones, and alcohols. and is marketed by the Universal Oil Products The above objects are accomplished by treating Other catalysts may be employed however, such as phosphoric butadiene or other unsaturated hydrocarbons with water in the presence of a catalyst, whereby 55 acid alone or partially neutralized, which may or 2,408,970 3 4 may not be deposited on carriers such as siliceous but one of its most unusual aspects is that it will materials, kieselguhr, clay, and the like. Oxides take place selectively with the acetylenes even or halides of heavy metals such as those of groups I and II such as mercury, silver, copper, cadmium, in the presence of other hydrocarbons in molal excess over the acetylenes, i. e., in hydrocarbon zinc, magnesium and the like, and mixtures of 5 mixtures containing acetylenes in admixture with easily reducible oxides such as those of silver and larger amounts of other unsaturated hydrocar mercury with di?icultly reducible oxides such as bons, especially when the other unsaturated hy those of zinc, copper and the like, are also effec drocarbons include diole?ns. It appears that tive. The contact time employed in the process either the acetylenes or their hydration products will vary with the activity of the catalyst used, 10 act as inhibitors for the hydration of the buta being shorter for the more active catalysts. diene or other unsaturated hydrocarbons. The process of this invention may be carried out The oxygenated organic compounds formed in with catalysts such as the above, at temperatures the reaction are useful as chemicals, solvents, between about 150° C. and 700° 0., although tem perfumes, etc., as mentioned earlier, and may also peratures between about 300° C. and about 500° C. 15 be used as azeotrope formers and as selective are preferred. The total or overall pressure may solvents for the separation, for example, of the be as high as about 5 atmospheres, but the par butanes and butenes from the butadiene and acet tial pressure of the unsaturated hydrocarbons ylenes of the C4 out. They are also useful as sol should be below about 300 mm. of mercury and vents for the dewaxing of oil and the deoiling preferably below 100 mm. of mercury. In the 20 of wax, and for many other purposes. above example it may be noted that the total Other modi?cations‘ of this invention which pressure was substantially one atmosphere and would occur to one skilled in the art are to be in the partial pressure of the unsaturated hydrocar cluded in the scope of this invention as de?ned bons (butadiene plus butenes plus acetylenes) was in the following claims. about 0.11 atmosphere or about 84 mm. of mer 25 We claim: cury. Where the unsaturated hydrocarbons in 1. A process for the puri?cation of diole?ns clude butadiene or other diole?ns, it is desirable which are contaminated by the presence of rela that the partial pressure of the diole?ns be below tively small proportions of acetylenes of approxi about 50 mm. of mercury. In the above example, mately the same boiling points, which comprises the butadiene partial pressure was 84><54/97= 30 reacting a hydrocarbon mixture containing said 4'? mm. acetylenes and diole?ns with water in the vapor The low partial pressures described above are phase in the presence of a catalyst at a tempera preferably attained by dilution with steam, but ture above about 300° C. and a partial pressure of dilution with other inert gases such as ?ue gases, diole?ns below about 100 mm. of mercury, where nitrogen, or saturated hydrocarbons may also be 35 by the acetylenes are converted to oxygenated made, providing that there is at least one mol derivatives, and the diole?ns are substantially unchanged. of water present to react with every mol of acet ylenic hydro-carbon present. It is desirable, how 2. A process for the puri?cation of butadiene ever, to have the molal ratio of water to acetylenes which is contaminated with relatively small pro 100 or more to l. A ratio of water to total un 40 portions of acetylenes of similar boiling point, saturates in the region of about 5 to 1 to 15 to 1 which comprises reacting a hydrocarbon mixture appears to be desirable. containing said acetylenes and butadiene with The invention is not con?ned to the treatment water in the vapor phase in the presence of a of C4 fractions containing butadiene, although catalyst at a temperature above about 300° C. this is a preferred embodiment. Propylene and 45 and a partial pressure of diole?ns below about ethylene fractions may also be freed of methyl 100 mm. of mercury, whereby the acetylenes are acetylene and acetylene by this method; C5 frac converted to oxygenated derivatives, and the bu tions containing mono-ole?ns and diole?ns such as cyclopentadiene, isoprene, and the like may be tadiene is substantially unchanged. 3. A process according to claim 2 in which freed of diacetylene, dimethyl acetylene, isopropyl 50 the catalyst is a siliceous solid phosphoric acid catalyst. and isopropenyl acetylenes, and the like; or higher molecular weight fractions may also be freed cf acetylenes. By the term acetylenes it is meant to include any hydrocarbon compound containing at least one triple bond. The reac tion may be carried out in the liquid phase, es pecially with the higher molecular weight frac tions, but is preferably carried out in the vapor phase. The reaction may also be carried out in the absence of other unsaturated hydrocarbon, 60 4. A process according to claim 2 in which the catalyst is an oxide of a heavy metal of groups 1 and 2 of the periodic system. 5. A process according to claim 2 in which the catalyst is a halide of a heavy metal of groups 1 and 2 of the periodic system. THOMAS F. DOUMANI. DAVIS A. SKINNER.