~ APPLIED CATALYS I S A: GENERAL ELSEVIER Applied Catalysis A: General 140 (1996) 99-110 n-Heptane reforming in a system of reactors-interstage membrane to separate hydrogen Jawad K. All, Alfons Balker * Department of Chemical Engineering and Industrial Chemisto,, Swiss Federal Institute of Technology, ETH-Zentrum, CH-8092 Ziirich, Switzerland Received 21 October 1995; accepted 9 January 1996 Abstract A system of two plug-flow reactors equipped with an interstaged tubular palladium-silver (Pd-Ag) membrane for ex situ H 2 separation, was tested for n-heptane reforming on a commer- cial Pt/A1203 catalyst. This system afforded a 65% higher toluene yield at 400°C and 17 bar than the same system without interstage membrane. Proper control of the permeate H2 pressure inside the membrane unit seemed to be crucial for maintaining the permeability of the membrane. Low H 2 pressures resulted in a decrease of H 2 permeability. Keywords." Dehydrocyclization: n-Heptane; Toluene; Hydrogen permeation; Palladium-silver membrane; Platinum 1. Introduction Catalytic reforming of naphtha is a major source of aromatics for the petrochemicals industry and is an important process for increasing the octane rating of gasoline. Both mono- and bimetallic noble metal catalysts are em- ployed in naphtha reforming, however, it is well known that the addition of Re, Sn, Ir or Ge to the commercial Pt/A1203 reforming catalysts results in significant improvement in activity and selectivity. An important reaction in catalytic reforming is the dehydrocyclization (DHC) of paraffins to aromatics * Corresponding author. Fax. (+ 41-1) 6321163, e-mail baiker@tech.chem.ethz.ch. 0926-860X/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved PII S0926- 860X(96)00024-5