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Es- 2214464- Cluvorres Patented Sept Sept. 25, 1951 C. E. MORRELL. ET AL 2,569,384 RECOVERY OF OXYGENATED COMPOUNDS FROM HYDROCARBON OILS Filed Dec. 19, l947 ; ; Z O H U C Y - X Charles22g E. 72 ZZ Sr. Verators es- 2214464- Cluvorres Patented Sept. 25, 1951 2,569,384 UNITED STATES PATENT office 2,569,384 RECOVERY OF OXYGENATED COMPOUNDS FROM HYDROCARBON OLS Charles E. Morrell, Westfield, and James E. McAteer, Cranford, N.J., assignors to Standard Oil Development Company, a corporation of Delaware Application December 19, 1947, Serial No. 792,802 1. 1. Claims, (C. 260-450) 2 This invention relates to the recovery of the Oxygen-containing compounds of One to four lower molecular weight neutral oxygen-contain carbon atoms will enter the aqueous phase while ing organic compounds from mixtures thereof the bulk of the compounds containing five car with hydrocarbon oils by a process involving the bon atoms and more per molecule will be found extraction of Such mixtures with dilute aqueous 5 in the oil layer, although it should be borne in carboxylic acid solutions, such as dilute aqueous mind that the separation of materials into their acetic acid, dilute aqueous propionic acid, etc., respective phases is oftentimes not cleancut and Or mixtures of the same. depends to a large extent upon the conditions Warious processes are known to the art in involved and the over-all composition of the Which a mixture of hydrocarbons and Organic O materials in the condensate from the Synthesis Oxygen-containing compounds are produced. reactor. Some of these processes are the low temperature Processes have been developed for the Sepa carbonization of coal, peat and similar materials, ration and recovery of alcohols, ketones, alde the destructive hydrogenation and distillation of hydes, etc. from the water layer. The starting coals, Wood, shales, etc. Numerous oxidation 15 point in many of such processes is a crude alcohol processes, particularly oxidation of petroleum oil distillation in which the water layer is subjected fractions, such as is described in Ellis' Chemistry to distillation to remove substantially all of the of Petroleum Derivatives, vol. 1, chapter 36, pages oxygenated compounds other than acids there 830 to 845, also yield mixtures of oxygenated from. Generally speaking, it is desired to leave compounds and hydrocarbons of substantially the acids, such as acetic acid, propionic acid, the same boiling range. This invention is par etc., in the bottoms from which they are sub ticularly applicable to the hydrocarbon syntheses, sequently recovered. such as the Fischer synthesis wherein oxides of It is an object of this invention to provide a carbon are reacted with hydrogen in the presence method for the recovery of oxygenated Coms of catalysts to produce synthetic hydrocarbons, 25 pounds, particularly water-soluble oxygenated water and numerous organic oxygenated com compounds from mixtures thereof with hydro pounds, predominantly aliphatic. The oxygen carbon oils. ated compounds produced in the Synthesis oper It is an object of this invention to provide a ation may be a major product or a relatively Small method for the recovery of oxygenated come by-product depending upon the Operating con 30 pounds from the Synthesis oil layer. ditions. These oxygenated materials which are It is also an object of this invention to provide extremely valuable as chemicals, consist of a a method for the separation and recovery of mixture of alcohols, acids, aldehydes, ketones and neutral organic oxygenated compounds and of esters and are difficult to separate from the hy acidic organic oxygenated compounds from mix drocarbon oil because first, they are so numerous, 35 tures of both with hydrocarbon oils. secondly they boil within substantially the same It is also an object of this invention to provide range as the hydrocarbon oils and, thirdly, they a means for allowing the oxygenated compounds often form azeotropes with each other and with normally included in the synthesis oil layer to be the hydrocarbon oils. purified and concentrated along with the oxy Normally when the products of the above-de 40 genated compounds normally obtained in the Scribed synthesis operation are condensed and al water layer. lowed to settle, the condensate separates into a These and other objects of this invention are di-phase System, that is, an upper oil layer con attained by carrying out the extraction of a mix prising substantially hydrocarbons and hydro ture of neutral and acidic oxygenated Organic carbon-Soluble Oxygen-containing materials and 5 compounds in hydrocarbon oils with a dilute a lower water phase comprising substantially aqueous solution of acetic acid which may or water and water-soluble oxygen-containing ma may not contain Small amounts of homologues terials. The oxygen-containing organic con of acetic acid. The acid bottons obtained from . pounds formed in the Synthesis operation range the fractional distillation of the Synthesis Water from very low molecular Weight compounds to 50 layer is especially suitable for this extraction step very high molecular weight compounds and as Will be further explained below. therefore find themselves distributed throughout The material subjected to extraction, accord the oil phase and the water, phase depending on ing to the terms of this invention, is complex their solubilities in these respective phases. In in nature. It is composed of hydrocarbons in general, it can be said that the bulk of the organic 55 cluding paraffins, olefins and in some cases, Small 2,569,884 3 4. amounts of aromatics. In addition, it contains pecially true when it is desired to extract the oxy anywhere up to about 50% or more of oxygen genated compounds from the lower boiling por containing materials, particularly of high molecu tions of the Fischer synthesis oil, say for instance lar weight such as those set out above. In cases the gasoline fraction (up to 400 F.), or some where the material is derived from the hydrocar lower boiling portion of the gasoline fraction. bon synthesis operation, the oil will have dissolved This invention also includes an alternate possi in it alcohols, acids, aldehydes, ketones and es bility in which a lower alcohol such as methyl, ters. Frequently, the esters predominate among ethyl or isopropy or mixtures of these lower alco the high boiling compounds, particularly that hols or mixtures of these with other neutral oxy fraction boiling above 350 F. while carbonyl con genated compounds such as ketones are added to pounds, that is aldehydes and ketones, acids and the aqueous acidic bottoms and this mixture em alcohols, predominate among the oxygen-contain ployed as the extraction agent. For instance, if ing compounds boiling at temperatures up to the entire Fischer synthesis oil is to be extracted about 350° F. Ordinarily the amounts of alcohols or if only the higher boiling portions thereof are and acids found decrease with increasing analyti extracted, it is desirable that considerable cal distillation temperatures due undoubtedly to amounts of the lower boiling oxygenated com the fact that they undergo esterification reactions pounds be added to the aqueous bottoms in order during such distillation treatments. The oxygen to obtain a suitable solvent for the extraction. content of the hydrocarbon oils resulting from the Preferably, however, the amount of alcohols or synthesis operation generally runs from one other low boiling oxygenated compounds com weight percent to ten weight percent. bined with the aqueous bottons is kept at the It has been found that when such a mixture of lowest value consistent with reasonable capacity hydrocarbon oils and oxygenated compounds is and selectivity of the extraction agent for the extracted at low temperatures with a dilute aque oil-soluble oxygenated compounds. Best results ous solution of acetic acid with or without a Small have been obtained by the addition of at least 20 amount of its homologues, the lower molecular volume per cent alcohol, particularly methanol. weight neutral oxygenated compounds present in The aqueous bottoms, either as such or after the mixture are extracted therefrom by the acid reinforcement with lower boiling oxygenated con solvent, leaving the lower molecular weight acids pounds as described above, may be contacted with contained in the mixture in the raffinate phase 30 the oil or suitable fractions thereof under a ya with the hydrocarbon oils. That is to say, the riety of conditions. For instance, the contacting alcohols, esters, ketones, aldehydes, acetals, etc., may be carried out in a batch manner. Prefers through C5 and some Cs, are dissolved by the di ably, however, it is carried out using countercur lute aqueous acetic acid and constitute the extract rent flow of the extractant and the oil, either in phase, while the acids present in the mixture are counter-stage equipment or in a countercurrent undissolved and together with the hydrocarbon packed or plate tower. The optimum solvent to oils in the mixture constitute the raftinate phase. oil ratio will vary over wide ranges depending. The dilute aqueous acetic acid solution en upon the nature of the solvent, i. e. the acid and ployed as the selective solvent according to the lower boiling oxygenated compound-content terms of this invention should contain no more 46) thereof, the oxygenated compound content of the than 5 to 10 weight per cent of acetic acid. The oil, the boiling range of the of being extracted, preferred range is 2 to 5 weight per cent. If other and the temperature of the extraction. As the higher homologues of acetic acid are present they oxygenated compound content of the Solvent is should be restricted to no more than about 35 increased, the optimum solvent/oil ratio, in gen weight per cent based on the weight of acetic acid. eral, decreases. Also the lower the oxygenated The acid water bottoms obtained from the frac compond content of the oil feed, the lower the tional distillation of the synthesis water layer solvent/oil ratio requirements.
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