Patent GB-824297-A (GB)
Title: Improvements in the separation of mixtures in the presence of a carrier gas
IPC: B01D53/14
Filed: 1956-03-23
Abstract: <PICT:0824297/III/1> Vaporizable components are separated from a mixture of substances resulting from a chemical reaction by passing a carrier-gas through the mixture whereby the vapours of two or more of the vaporizable components of the mixture are entrained in the gas, then contacting the vapour-laden gas, in a material-exchange device such as a column packed with Raschig rings, with a countercurrent stream of liquid comprising a condensate obtained by partial or total condensation of the vapours from the gas, and withdrawing from the exchange-device (1) liquid containing the less volatile component(s) and (2) gas containing the more volatile component(s).  The process may be carried out in conjunction with a chemical reaction wherein the carrier gas forms one of the reactants.  In an example, butanol is synthesized from water, propylene and carbon monoxide using N-n-butylpyrrolidine and iron pentacarbonyl as solvents and catalysts.  The two latter substances and the water are introduced into the base of the reactor 2; and the propylene and carbon monoxide are introduced into the system through line 3.  This gas mixture flows up column 19 and through condenser 23, and is then passed through line 26 where it mixes with recycle gas; the mixture is then pumped into the base of reactor 2.  The reaction takes place at a pressure of 10 atmospheres and a temperature of 110 DEG  C.  The gas-vapour mixture leaving the top of the reactor passes up through column 5, which is filled with Raschig rings, and is contacted therein with a downflowing stream of aqueous butanol.  The gas leaving the top of column 5, which is completely freed from butyl pyrrolidine, flows to condenser 7 which is maintained at 30 DEG  C. The condensate, which collects in separator 9, forms three liquid layers.  The lowest layer, which is rich in iron carbonyl, is passed through line 32 into reactor 2.  The middle layer and half the top layer are supplied through line 33 as contact-liquid for column 5. The liquid withdrawn from the sump of column 5 is passed to the reactor through line 16.  The gas leaving separator 9 is recycled to the reactor, provision being made for the removal of carbon dioxide (by-product) in apparatus 31.  The remaining half of the top liquid layer from separator 9 is heated in heater 21 and is then introduced into the top of column 19.  As the liquid flows down this column the iron carbonyl, together with some of the butanol and water, are evaporated from it by the rising gaseous mixture of propylene and carbon monoxide.  Aqueous butanol is withdrawn from the base of column 19.  The gas-vapour mixture from the top of column 19 is passed to condenser 23.  The condensate flows via separator 24 to separator 9; and the gas flows through line 26 to join the circulating-gas.  Other examples relate to the synthesis of (1) cyclo-octatetraene from acetylene, and (2) butyl acrylate from acetylene, carbon monoxide and butanol.ALSO:In a process for separating the products of reactions such as the synthesis of (a) butanol, (b) butyl acrylate, or (c) cyclo-octatetraene, wherein the effluent from the reactor is entrained in a carrier gas (carbon dioxide and/or acetylene), the vapour-laden gas is contacted, in a material-exchange device such as a column packed with Raschig rings, with a countercurrent stream of a liquid comprising a condensate obtained by partial or total condensation of the vapours from the gas, and withdrawing from the exchange device (1) liquid containing the less volatile component(s) and (2) gas containing the more volatile component(s).  In Example 2, butanol is synthesized from water, propylene and carbon monoxide using N-n-butylpyrrolidine and iron pentacarbonyl as <PICT:0824297/IV (b)/1> solvents and catalysts. The two latter substances and the water are introduced into the base of reactor 2; and the propylene and carbon monoxide are introduced into the system through line 3. This gas mixture flows up column 19 and through condenser 23, and is then passed through line 26 where it mixes with recycle gas; the mixture is then pumped into the base of reactor 2.  The reaction is carried out at a pressure of 10 atmospheres and a temperature of 110 DEG C.  The effluent leaving the top of the reactor passes up through column 5, which is filled with Raschig rings, and is contacted therein with a downflowing stream of aqueous butanol.  The gas leaving the top of column 5, which is completely freed from butyl pyrrolidine, flows to condenser 7 which is maintained at 30 DEG  C.  The condensate, which collects in separator 9, forms three layers.  The lowest layer, which is rich in iron pentacarbonyl, is passed through line 32 into reactor 2.  The middle layer and half the top layer are supplied through line 33 as contact-liquid for column 5.  The liquid withdrawn from the sump of column 5 is passed to the reactor through line 16.  The gas leaving separator 9 is recycled to the reactor, provision being made for the removal of carbon dioxide (by-product) in apparatus 31.  The remaining half of the top liquid layer from separator 9 is heated in heater 21, and is then introduced into the top of column 19.  As the liquid flows down this column the iron pentacarbonyl, together with some of the butanol and water, are evaporated from it by the gaseous mixture of propylene and carbon monoxide, which is ascending the column.  Aqueous butanol is withdrawn from the base of column 19. The gas-vapour mixture from the top of column 19 is passed to condenser 23.  The condensate flows via separator 24 to separator 9; and the gas flows through line 26 to join the circulating-gas. Example 5 relates to the same synthesis of butanol; but in this case fresh water is added to the middle liquid layer in separator 9. Example 3 relates to the synthesis of cyclo-octatetraene from acetylene in tetrahydrofurane as solvent at a pressure of 15 atmospheres and a temperature of 100 DEG  C.  Example 4 relates to the synthesis of butyl acrylate from acetylene, carbon monoxide and butanol, in the presence of acetone as solvent, at a pressure of 50 atmospheres and a temperature of 175 DEG  C.  The process may also be applied to the separation of reaction mixture obtained in the synthesis of carboxylic acids (not specified) from a mixture of olefin, carbon monoxide and water in the presence of nickel carbonyl catalyst. In this case, the reaction mixture is contacted with a countercurrent stream of carbon monoxide under superatmospheric pressure, which obviates the decomposition of the nickel carbonyl.