GB1014882A - Improvements relating to the reactivation of catalysts - Google Patents

Abstract

In a hydrocarbon conversion process, e.g. isomerization, carried out using a catalyst prepared by contacting a halogenatable inorganic oxide of an element of Groups II to V of the Periodic Table with a compound of the formula <FORM:1014882/C4-C5/1> (where X and Y may be the same or different and are H, Cl, Br, F or SCl, or where X and Y together may be oxygen or sulphur) under non-reducing conditions and at a temperature such that chlorine is taken up by the oxide without the production of free chloride of the element from Group II to V, said conversion process operating at elevated temperature and pressure in presence of hydrogen, the catalyst is at least partially reactivated by stopping the flow of hydrocarbon feedstock when evidence of catalyst deactivation is apparent, continuing to pass the hydrogen until the catalyst is at least partially reactivated and then recommencing the flow of feedstock. Preferably, the passage of hydrogen is continued at a pressure below the conversion pressure, e.g. at least 50 p.s.i.g., the duration of the reactivation step being 1 to 100 hours. The isomerization process is carried out in either liquid or vapour phase using C4 or higher paraffin hydrocarbons boiling up to 400 DEG F. at temperatures below 400 DEG F., the isomerization pressure being 100 to 2000 p.s.i.g., the isomerization and reactivation temperatures and hydrogen flow rate being the same. Specified catalyst are refractory oxide selected from Groups II to V of the Periodic Table, e.g. alumina, boria, silica, titania or zirconia which may be used in admixture. Preferably the catalyst contains (1) less than 25% weight of a metal N compound having hydrogenating activity selected from Groups VIA and VIII, e.g. platinium or palladium, and (2) 1 to 15% weight of chlorine in amounts of from 2.0 x 10-4 to 35 x 10-4 gms./sq. metre of catalyst surface area. The example describes the isomerization of a C6 refinery light gasoline fraction, which has been previously dried, desulphurized and dearomatized, at 270 DEG F., 250 p.s.i.g. total pressure, the reactivation step taking 4 hours at 250 p.s.i.g. and 12 hours at 100 p.s.i.g. to give increased catalyst activity measured in terms of the percentage yield of 2.2 dimethylbutane after each reactivation step, the reactivation step being carried out two times.