Patent GB-481646-A (GB)
Title: An improved manufacture of butadiene
IPC: C07C11/167
Filed: 1937-06-16
Abstract: <PICT:0481646/III/1> Butadiene is obtained by a process in which normal butane is catalytically dehydrogenated, with formation of butylene but without substantial formation of butadiene, in one step, followed by catalytic dehydrogenation of a portion of the butylene to butadiene in a second step, the butadiene being removed and the remaining hydrocarbons of four C atoms recirculated.  The first dehydrogenation step is carried out at a pressure of 25-80 pounds per square inch, at a temperature of 900-1000 DEG  F. and to an extent of conversion of 20-60 per cent per pass.  The second step is carried out at normal or reduced pressure and at a temperature of 1000-1200 DEG  F.  The residual butylene after removal of butadiene may be polymerized, the unpolymerized hydrocarbons separated therefrom and recirculated to the first step and the butylene depolymerized and recirculated to the second step.  A suitable catalyst for the dehydrogenations is chromium oxide on activated alumina.  Butadiene is removed by extraction of the liquid hydrocarbons with liquid ammonia or ethylene glycol, or by absorption from the gases by acid cuprous chloride.  In an apparatus for carrying out the process, butane is forced from a storage tank 1 through heat exchanger 5 to a dehydrogenator 7, cooler 10 and separator 11.  Fixed gases are removed at 12 and unconnected butane and butylene pass to dehydrogenator 15, where they are treated at atmospheric or preferably reduced pressure, thence to cooler 17 and extractor 22. The extract containing butadiene is taken off at 24 and separated in a still 25.  The gases from the extractor 22 are compressed and passed to a separator 32 for removing "fixed gases" and hydrogen from the C4 hydrocarbons which are either returned to the butane dehydrogenator 7 or the dehydrogenator 15 or, if substantial amounts of butylene are present, transmitted to a polymerizer 40 containing sulphuric acid or other catalyst.  Polymers are separated from butane &c. which is passed through line 43 to the dehydrogenator 7; the polymers passing to depolymerizer 47 containing marsil clay &c., the butylene produced passing to dehydrogenator 17. p ALSO:Butadiene is obtained by a process in which normal butane is catalytically dehydrogenated, with formation of butylene but without substantial formation of butadiene, in one step, followed by catalytic dehydrogenation of a portion of the butylene to butadiene in a second step, the butadiene being removed and the remaining hydrocarbons of four C atoms recirculated.  The first dehydrogenation step is carried out at a pressure of 25-80 pounds per square inch, at a temperature of 900-1000 DEG  F. and to an extent of conversion of 20-60 per cent per pass.  The second step is carried out at normal or reduced pressure and at a temperature of 1000-1200 DEG  F.  The residual butylene after removal of butadiene may be polymerized, the unpolymerized hydrocarbons separated therefrom and recirculated to the first step and the butylene depolymerized and recirculated to the second step.  A suitable catalyst for the dehydrogenations is chromium oxide on activated alumina.  Butadiene is removed by extraction of the liquid hydrocarbons with liquid ammonia or <PICT:0481646/IV/1> ethylene glycol, or by absorption from the gases by acid cuprous chloride.  In an apparatus for carrying out the process, butane is forced from a storage tank 1 through heat exchanger 5 to a dehydrogenator 7, cooler 10 and separator 11.  Fixed gases are removed at 12 and unconnected butane and butylene pass to dehydrogenator 15, where they are treated at atmospheric or preferably reduced pressure, thence to cooler 17 and extractor 22. The extract containing butadiene is taken off at 24 and separated in a still 25.  The gases from the extractor 22 are compressed and passed to a separator 32 for removing "fixed gases" and hydrogen from the C4 hydrocarbons which are either returned to the butane dehydrogenator 7 or the dehydrogenator 15 or, if substantial amount of butylene are present, transmitted to a polymerizer 40 containing sulphuric acid or other catalyst.  Polymers are separated from butane &c. which is passed through line 43 to the dehydrogenator 7; the polymers passing to depolymerizer 47 containing marsil clay &c., the butylene produced passing to dehydrogenator 17.