Patent GB-842969-A (GB)
Title: Process for the production of monovinyl acetylene of high purity
IPC: C07C11/30
Filed: 1958-12-10
Abstract: <PICT:0842969/IV(b)/1> <PICT:0842969/IV(b)/2> The separation of the gas mixture from the polymerisation of acetylene to monovinylacetylene or from the preparation of acetonitrile from acetylene and hydrogen cyanide and from which acetonitrile has been washed out is effected by, in a first stage, washing with an oil to absorb all but the major portion of the acetylene which is recycled to the reaction and recovering from the absorbent a gas mixture of monovinylacetylene and acetylene and, separately, divinylacetylene, chloroprene and higher acetylene polymers and in a second stage, separating by washing the gas mixture from the first stage into pure monovinylacetylene and acetylene which is recycled to the reaction. The gas mixture from the reaction passes to absorber 1 (Fig. 1) where it is contacted with a wash oil which preferentially absorbs monovinylacetylene and is preferably a polycyclic aromatic hydrocarbon with branched side chains boiling in the range 170-220 DEG C or an aromatic tar oil containing 95% by weight of alkylated aromatic hydrocarbons and boiling in the range 170-190 DEG C. Acetylene leaves by line 3 for recycle.  The wash oil containing some acetylene and all the monovinylacetylene, divinylacetylene, chloroprene and higher polymers passes to heater 8 where monovinylacetylene and acetylene are expelled by line 43 passing to an after-wash with a small amount of oil in washer 45, the sump product of which is passed to the heater and the overhead of which is passed by line 48 to the second stage (Fig. 2).  Oil from the heater 8 is stripped in tower 10 with a portion of the starting gas from line 11.  The overhead is condensed and then heated to expel acetylene and monovinylacetylene which pass to the after-wash while the oil is then stripped in tower 38., e.g with an inert gas, flue gas or a combustion gas such as coke over gas or carbide furnace gas. The oil is then recycled by line 42.  Oil from the bottom of stripper 10 is partly recycled by line 14 and partly passed by line 16 for distillation to remove higher acetylene polymers before recycling by line 25.  The gas from line 48 passes to the second stage absorber 49 (Fig. 2) which may employ the same oil as in the first stage but preferably acetone.  Acetylene leaves by line 76 and is washed with water before recycling to the reaction.  The solution of monovinylacetylene in acetone is heated in tower 53 to expel monovinylacetylene, the acetone being recycled by line 55.  The monovinylacetylene is water washed and obtained as pure product in line 65.  The water from the water washings is distilled in fractionator 67 to obtain acetone which is recycled by line 73 and water recycled by line 74.ALSO:<PICT:0842969/III/1> <PICT:0842969/III/2> The separation of the gas mixture from the polymerization of acetylene to monovinylacetylene or from the preparation of acetonitrile from acetylene and hydrogen cyanide and from which acetonitrile has been washed out is effected by, in a first stage, washing with an oil to absorb all but the major portion of the acetylene which is recycled to the reaction and recovering from the absorbent a gas mixture of monovinylacetylene and acetylene p  and, separately, divinylacetylene, chloroprene and higher acetylene polymers and in a second stage, separating by washing the gas mixture from the first stage into pure monovinylacetylene and acetylene which is recycled to the reaction.  The gas mixture from the reaction passes to absorber 1 (Fig. 1) where it is contacted with a wash oil which preferentially absorbs monovinylacetylene and is preferably a polycyclic aromatic hydrocarbon with branched side chains boiling in the range 170-220 DEG C. or an aromatic tar oil containing 95% by weight of alkylated aromatic hydrocarbons and boiling in the range 170-190 DEG C.  Acetylene leaves by line 3 for recycle.  The wash oil containing some acetylene and all the monovinylacetylene, divinylacetylene, chloroprene and higher polymers passes to heater 8 where monovinylacetylene and acetylene are expelled by line 43 passing to an after-wash with a small amount of oil in washer 45, the sump product of which is passed to the heater and the overhead of which is passed by line 48 to the second stage (Fig. 2).  Oil from the heater 8 is stripped in tower 10 with a portion of the starting gas from line 11.  The overhead is condensed and then heated to expel acetylene and monovinylacetylene which pass to the after-wash while the oil is then stripped in tower 38 e.g. with an inert gas, flue gas or a combustion gas such as coke oven gas or carbide furnace gas.  The oil is then recycled by line 42. Oil from the bottom of stripper 10 is partly recycled by line 14 and partly passed by line 16 for distillation to remove higher acetylene polymers before recycling by line 25.  The gas from line 48 passes to the second stage absorber 49 (Fig. 2) which may employ the same oil as in the first stage but preferably acetone. Acetylene leaves by line 76 and is washed with water before recycling to the reaction. The solution of monovinylacetylene in acetone is heated in tower 53 to expel monovinylacetylene, the acetone being recycled by line 55. The monovinylacetylene is water washed and obtained as pure product in line 65.  The water from the water washings is distilled in fractionator 67 to obtain acetone which is recycled by line 73 and water recycled by line 74.