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UNITED States. PATENT OFFICE Patented May 31, 1949 2471,525 UNITED STATEs.2,471,525 PATENT . OFFICE. REACTION OF AN ACETYLENE WITE EF TO PRODUCE WNYL FLUORDE AND/OR DFLUoRoETHANE AND HOMOLOGUES. THEREOF John C. Hillyer and Joseph F. Wilson, Bartlesville, Okla., assignors to Philips Petroleum Company, a corporation of Delaware No Drawing. Application December 19, 1947, Seria No. 92,832 11 Claims. (C. 260-653) 1 2 This invention relates to the reaction of an of a reacting mixture passes up through it, or acetylene with hydrogen fluoride. In one aspect as a flowing stream of small, or even powdery, it relates to an improved process for the produc fluent particles, moving through a reaction Zone. tion of vinyl fluoride. In another aspect the in The reaction is exothermic, and some suitable, vention relates to an improved process for the conventional means should be used to maintain a production of 1,1-difluoroethane. In a broader desired reaction temperature and take up heat aspect the invention relates to an improved proc of reaction. The acetylene reactant may be acet :ess for producing difluorohydrocarbons. ylene, itself, or some homologue of higher molec The direct noncatalytic interaction of acet ular weight, preferably one having not more than ylene with hydrogen halides to produce vinyl O ten carbon atoms per molecule. halides is well known. However, this method . The product obtained from the reaction of acet of procedure, particularly when applied to the ylene itself comprises vinyl fluoride and 1,1-di hydrofluorination of an acetylene, is too ineffi fluoroethane in substantially equal proportions. cient, both as regards rate of reaction and yield Each of these materials has important uses in (of product, to have commercial significance. Cat s the chemical industries, and each can be read alysts such as mercuric oxide or mercuric halide ily recovered from the reaction products. Vinyl have been employed to activate the interaction of fluoride, heretofore in short supply due to the acetylene with other hydrogen halides, particu lack of a suitable method for its preparation, larly hydrogen chloride. However, attempts to has valuable applications in the production of use these catalysts for the hydrofluorination of 20 synthetic resins; 1,1-difluoroethane has valuable acetylene have resulted in numerous difficulties, -properties as a refrigerant, a propellant for aero Such as long induction periods before the reac sol-type insecticide sprays, and the like. When tion begins, poor yields of product, rapid deterio an acetylene of a higher number of carbon atoms ration of the catalyst, and the like. per molecule is reacted, the proportion of di We have discovered a process for the hydro 25 fluoro product is higher, and tends to become fluorination of an acetylene wherein the catas the sole primary reaction product. In Such a case lyst employed comprises aluminum trifluoride, both fluorine atoms become attached to the same aluminum oxide, or mixtures of these materials. carbon atom, which is generally the more cen When operating according to our process, induc- . tral, in the molecule, of the two initially-avail tion periods are short, reaction rates are high, 30 able, carbon atoms. The reaction mixture may and catalyst life is long. The degree of utiliza- - contain only the two reactants or, if desired, may tion of the acetylene is high and increases as the contain a diluent which is inert under the reac reaction proceeds, becoming substantially quan tion conditions, such as nitrogen, methane, Carr titative after a few hours. bon tetrafluoride, etc. : An object of this invention is to provide an 35 The aluminum trifluoride catalyst of our in improved process for the interreaction of an acet vention is preferably prepared in the form of ylene and hydrogen fluoride. pellets, by the use of small amounts of a binder Another object of this invention is to produce such as graphite, hydrogenated corn oil, and the vinyl fluoride. like. However, when desired, the aluminum tri . A further object of this invention is to produce 40 fluoride may be deposited on a carrier such as 1,1-difluoroethane. alumina, a bauxite high in alumina and with a ... Still a further object of this invention is to low silica content, etc., or may be combined with produce difluoro derivatives of paraffin hydro materials such as activated carbon to provide carbons. highly effective results. Further objects and advantages of this inven The mechanism by which Our aluminum oxide tion will become apparent, to one skilled in the catalysts operate is not entirely clear. It may art, from the accompanying disclosure and dis be possible that small amounts of an aluminum CuSSion. - fluoride, such as aluminum-oxyfluoride, in a high : In accordance with our invention, an acetylene 1y active state is formed on the catalyst surface. is mixed with hydrogen fluoride and contacted SO However, if such a change in the initial aluminum with the catalyst. The catalyst is preferably in oxide occurs, the quantity of such an aluminum -a granular or pulverulent form, and may be em fluoride is exceedingly small. A granular mates ployed either as a fixed bed of coarse catalyst rial which is aluminum oxide initially is a good granules, as a single bed of Small, even powdery, catalyst for the reaction herein discussed, how fluent particles in ebullient motion as a stream sever, whatever the source of the catalytic ac 2,471,525 3 4. tivity, and the above suggestion is offered merely reaction was halted. During the reaction 167.2 for general interest. liters of acetylene was charged, 5.2 liters of which Before contacting with the reactants the cat- was recovered unreacted. alyst is preferably dried by heating, in the cat- Fractionation of the product provided 180 cc. of alyst case, in a stream of inert gas. In the prac- 5 vinyl fluoride (B. P-72.2°C.) and 160 cc. of 1,1- tice of our process the acetylene and hydrogen difluoroethane (B. P.-24 C.), the remainder fluoride are mixed, preferably with a molar excess being dissolved acetylene. of hydrogen fluoride, in a ratio of up to about Eacample II fifteen mols of hydrogen fluoride (HF) to one mol ple of acetylene hydrocarbon, and passed over the 10 Tne procedure of Example I was repeated catalyst at a temperature between 350 and 750 F., using similar feed stock and reaction conditions. preferably between 450 and 650 F. The flow rate After 32 hours Operation the temperature in the of the reaction mixture should be between 150 catalyst zone was reduced to 500 F. to observe and 400, preferably between 200 and 300 vol- whether catalyst activity would continue when so umes (standard conditions) per volume catalyst 5 operating. The yield per hour continued to in per hour. Pressures will, in general, be substan- crease for a period of eight hours at which time tially atmospheric, although values somewhat the run Was discontinued. above or below this level, such as up to about 50 Eacomple III pounds per square inch gage, may be employed, p when desired. At the beginning of each run a 20 A steel tube, was charged with 200 cc. of pel short induction period is usually observed with leted aluminum oxide. The tube was then heated aluminum trifluoride, generally from about ten to at a temperature of 600°F. for six hours to dry about 30 minutes in length, although there is the catalyst, moisture being swept from the tube substantially no induction period with aluminum by a stream of dry nitrogen. Acetylene and hy oxide. 25 drogen fluoride were commingled, in a mo) ratio Efluent from the catalyst Zone is treated to re- of 1:1.54, and passed over the catalyst at a rate of cover various constituents. In such a separa- 142.5 volumes per volume of catalyst per hour. tion, the effluent may be treated to separate hy- Effluent gases were passed through a steel tube drogen fluoride, as by being passed over sodium containing sodium fluoride, to remove unreacted fluoride, after which it is condensed and frac- 30 hydrogen fluoride, after which they were con tionated to separate an olefinic monofluoride, densed in a Dry Ice-cooled trap. and/or a difluorohydrocarbon. Unreacted acet- At the end of eight hours the proportions uf ylene reactant may be recycled and, if only a acetylene and hydrogen fluoride were changed to difluoro hydrocarbon is desired, the olefinic provide a mol ratio of 1:1.62 and the run con monofluoride produced may be returned for 35 tinued for 6.5 hours. Ratios of feed materials and further reaction. flow rates were altered from time to time and the In the following examples, the data are pre- volume of . product determined as the reaction sented as being typical of the invention, and such proceeded until the catalyst had been used for a data should not be construed to limit the inven- total of 38.5 hours. Data on the entire operation tion unduly. 40 are shown in the accompanying table. Average Time. Mol Ratio Flow Rate Contact. Avg. Yield 1 Unreacted Tenp.OF. Hrs. p CH:HF w/v.IHrs. TimeSec. catalystcc.fcc. PerCH, Cent 600 8.0 11.54 i42.5 ii. 4 0.098 28.2 600 6.5 : 62 79.0 9.5 O. 119 29.8 600 8.0 1:1. 57 198.5 8.5 0.136 28.8 600 8.0 1:2.43 317.5 5.2 0.89 25.6 600 8.0 1:11 85. 0 8.9 0.17 22.3 Yield based on total liquid product. Fractionation showed this product to comprise 44.7 per cent (average value) vinyl fluoride and 40.6 percent 1.1-difluoro ethane.
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