GB498512A - Process for the isomerisation of normal butane - Google Patents

Abstract

Normal butane is converted into isobutane by subjecting it to contact with a catalyst comprising aluminium chloride in the presence of hydrogen chloride at elevated temperatures, preferably of the order of 150-200 DEG C., the aluminium chloride being used in an amount not exceeding 20 per cent, and the hydrogen chloride in an amount not exceeding 5 per cent by weight of the normal butane. Alternatively, normal butane mixed with not more than 5 per cent of hydrogen chloride is passed continuously through a granular catalyst comprising anhydrous aluminium chloride on a relatively inert carrier at temperatures of about 150-200 DEG C. and under superatmospheric pressure, preferably above 10 atmos., to effect the isomerization. The granular catalysts comprising a mixture of anhydrous aluminium chloride, and carriers such as fuller's earth, silica, firebrick, or activated carbon may be used in the batch as well as the continuous process. In examples: (1) butane is heated together with 20 per cent aluminium chloride and 2 per cent hydrogen chloride for 12 hrs. at 150 DEG C., the initial pressure of 5 atmos. rising to about 30 atmos.; (2) butane with about 2 per cent hydrogen chloride is passed through a granular catalyst comprising about equal weights of activated carbon and aluminium chloride at about 200 DEG C. and 44 atmos., the space velocity being about 0,8 kgs. of butane per kg. of catalyst per hour.