GB830439A - Catalytic reforming process - Google Patents

Abstract

<PICT:0830439/IV (b)/1> The reforming of naphtha containing naphthenes but devoid of more than innocuous amounts of sulphur, nitrogen, arsenic, water and halogen is effected in the presence of hydrogen and a platinum-type catalyst in two steps which comprise (a) maintaining the naphtha in a first step at above the autogenous quench point temperature (see below) with a minimum amount of catalyst necessary to produce a maximum temperature differential between the vapour inlet and the autogenous quench point and (b) in the second step contacting the product at at least 500 DEG C. with sufficient catalyst to provide an on-stream of at least 3 months. The autogenous quench point is the point in the first reactor at which dehydrogenation of naphthenes, for practical purposes, ceases and is independent of the age of the catalyst, the vapour inlet temperature, the composition of the naphtha or the mol. ratio of hydrogen to naphtha; the autogenous quench point temperature is the temperature at that point and is dependent on the factors quoted. The point is discovered by a temperature profile curve for the reactor as shown; the graph is of temperature against distance through the reactor (as measured in kgs. of catalyst per 160 kilolitres of naphtha per stream day), the different curves being for different inlet temperatures and different catalyst ages. The point where the curve changes from being substantially horizontal is the autogenous quench point. Only that amount of catalyst necessary to attain the quench point is used in the first reactor; extra space may be filled with silica or alumina. The second stage may be effected in several reactors, the catalyst being equally divided and in a total amount compared to that in the first stage of 3 to 10 : 1.