GB498463A - Process for the isomerisation of normal pentane - Google Patents

Abstract

Normal pentane is converted into isopentane by subjecting it to contact with a catalyst comprising aluminium chloride in the presence of hydrogen chloride at temperatures of the order of atmospheric up to 200 DEG C., the aluminium chloride being used in an amount not exceeding 10 per cent, and the hydrogen chloride in an amount not exceeding 2 per cent by weight of the normal pentane. Alternatively, normal pentane mixed with not more than two per cent of hydrogen chloride is passed continuously through a granular catalyst comprising anhydrous aluminium chloride on a relatively inert carrier within the same temperature range and under superatmospheric pressure, preferably about 10 atmos. to effect the isomerization. Hydrocarbon fractions consisting largely of pentane such as low-boiling motor fuel fractions may be treated to increase their anti-knock rating. The granular catalysts comprising 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.ALSO:Normal pentane is converted into isopentane by subjecting it to contact with a catalyst comprising aluminium chloride in the presence of hydrogen chloride at temperatures of the order of atmospheric up to 200 DEG C., the aluminium chloride being used in an amount not exceeding 10 per cent, and the hydrogen chloride in an amount not exceeding 2 per cent by weight of the normal pentane. Alternatively, normal pentane mixed with not more than 2 per cent of hydrogen chloride is passed continuously through a granular catalyst comprising anhydrous aluminium chloride on a relatively inert carrier within the same temperature range and under superatmospheric pressure, preferably above 10 atmos., to effect the isomerization. Hydrocarbon fractions consisting largely of pentane such as low-boiling motor fuel fractions may be treated to increase their antiknock rating. The granular catalysts comprising 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. They may conveniently be maintained in suspension in the liquid hydrocarbon, the time of contact ranging from 1/2 hr. to 4-5 days according to the temperature. The products may be fractionated to recover the isomeric products, the unconverted hydrocarbon being returned. In examples: (1) pentane is introduced with 10 per cent aluminium chloride and 1 per cent hydrogen chloride into a vessel at about 5 atmos. which is heated for 3 hrs. at about 100 DEG C.; (2) pentane vapour with about 1 per cent by volume of hydrogen chloride is passed through a granular catalyst comprising about equal weights of aluminium chloride and activated carbon at 200 DEG C. and 30 atmos. Unconverted pentane is recycled.