Patent GB-589058-A (GB)
Title: Improvements in or relating to the catalytic isomerization of paraffinic hydrocarbons
IPC: C07C5/27
Filed: 1944-10-20
Abstract: In the isomerization of normal paraffins of at least 4 carbon atoms by passage with hydrogen halide in the vapour phase through a bed of aluminium halide sorbed on porous alumina, intermittent activation of the catalyst is effected by adding aluminium halide vapours while stopping the addition of hydrogen halide.  The aluminium halide vapours may be introduced by the paraffin feed or an inert gas such as carbon dioxide, nitrogen or hydrogen.  The feedstock such as n-butane or pentane, butane cuts or straight run naphtha may be pretreated with 90-100 per cent. sulphuric acid and passed through sorptive alumina before heating, to about 220-400 DEG F. for butane, and feeding through a perforated tube or plate to a tubular reactor charged with "Porocel" (Registered Trade Mark) preheated to 1000-1100 DEG F. to remove water, and mixed with aluminium chloride for the lower 2/3 rds of its height. The chloride is sublimed and sorbed on the "Porocel" by blowing with butane at about 340 DEG F. first at normal, then at 40-50 lbs. pressure.  The chloride content in the catalyst is about 5-20 weight per cent.  Hydrogen chloride equivalent to 2-8 weight per cent. of the butane is added to the feed after the catalyst is formed, the reactor temperature being about 220 DEG F. The product is freed from catalyst and permanent gases, stripped of hydrogen chloride which may be recycled, caustic washed, and fractionated to recover isobutane.  When reactivation is required, part of the butane feed is fed through an aluminium chloride pick up chamber at 220-350 DEG F., while the hydrogen chloride feed and recycle is discontinued.  The pick up chamber is then by-passed, the catalyst temperature reduced somewhat, and flow of hydrogen chloride resumed.  Specification 573,761, [Group IV], is referred to.ALSO:In the isomerization of normal paraffins of at least 4 carbon atoms by passage with hydrogen halide in the vapour phase through a bed of aluminium halide sorbed on porous alumina, intermittent activation of the catalyst is effected by adding aluminium halide vapours while stopping the addition of hydrogen halide.  The aluminium halide vapours may be introduced by the paraffin feed or an inert gas such as carbon dioxide, nitrogen or hydrogen.  The feedstock such as n-butane or pentane, butane cuts or straight-run naphtha may be pretreated with 90-100 per cent sulphuric acid and passed through sorptive alumina before heating, to about 220-400 DEG  F. for butane, and feeding through a perforated tube or plate to a tubular reactor charged with "Porocel" (Registered Trade Mark), preheated to 1000-1100 DEG  F. to remove water, and mixed with aluminium chloride for the lower 2/3 rds. of its height.  The chloride is sublimed and sorbed on the "Porocel" by blowing with butane at about 340 DEG  F., first at normal, then at 40-50 lbs. pressure.  The chloride content in the catalyst is about 5-20 weight per cent.  Hydrogen chloride equivalent to 2-8 weight per cent of the butane is added to the feed after the catalyst is formed, the reactor temperature being about 220 DEG  F. The product is freed from catalyst and permanent gases, stripped of hydrogen chloride which may be recycled, caustic washed, and fractionated to recover isobutane.  When reactivation is required, part of the butane feed is fed through an aluminium chloride pick-up chamber at 220-350 DEG  F. while the hydrogen chloride feed and recycle is discontinued.  The pick-up chamber is then byepassed, the catalyst temperature reduced somewhat, and flow of hydrogen chloride resumed.  Specification 573,761 is referred to.