n-Pentane Hydroisomerization on Pt Containing HZSM-5, HBEA and SAPO-11 Carmen M. Lo ´pez Yajaira Guille ´n Luis Garcı ´a Luis Go ´mez A ´ ngel Ramı ´rez Received: 13 April 2007 / Accepted: 18 October 2007 / Published online: 14 March 2008 Ó Springer Science+Business Media, LLC 2008 Abstract Hydroisomerization of n-pentane over platinum promoted acids zeolites was studied. The effect of structure and acidity of the support was investigated at atmospheric pressure between 250 and 400 °C. Pt/HDBEA catalyst showed the best performance at 300 °C with high activity and selectivity to isopentane, due to its structure and a proper balance between acid and metallic sites. This cata- lyst has a high catalytic stability and regeneration under air flow after deactivation by coking, restores its activity and selectivity. Keywords n-Pentane  Hydroisomerization  Supported-metal catalysts  Zeolites 1 Introduction The worldwide in the formulation of gasoline are the reduction of evaporative emissions and more complete gasoline combustion. The general reduction in the Reid vapour pressure, aromatics, alkenes, sulphur content, will have a negative impact on the octane number of the gas- oline pool, and also will reduce the total amount of gasoline produced. Taking into account the above scenario, it appears that branched paraffin components are the pre- ferred gasoline component. Isomerization of normal paraffin is of considerable interest and plays an important role in the petroleum industry [1]. The branching of n-paraffins C 4 –C 7 is needed to improve the octane number of gasoline [2, 3] while that of long-chain alkanes has been used in the dewaxing pro- cesses for production of high quality diesel fuel and lube base oil [4, 5]. The isomerization process usually takes place in the presence of hydrogen, and in this case is referred as hydroisomerization. An atmosphere of hydro- gen is used to minimize carbon deposits on the catalysts but hydrogen consumption is negligible. Reaction temperature of about 95–205 °C are preferred to higher temperatures because the equilibrium conversion to isomers is enhanced at the lower temperatures. In order to achieve the low temperature necessary to obtain an acceptable yield of isomers, the catalyst systems used in the early units were based on aluminium chloride in some form. These catalyst systems, however, had the drawback of being highly cor- rosive and difficult to handle. In recent years, catalyst of a different type has come in use. These are solid catalysts consisting of a support having an acidic carrier and a hydrogenation–dehydrogenation function, frequently a noble metal. In this sense, zeolites, as in many other reactions, have attracted a great interest due to their useful properties, such as acidity, shape selectivity and stability, as well as the availability of many different structures. Paraffin isomerization is a reaction typically catalyzed by very strong acid sites. More efficient than acid catalysts are metal-acid bifunctional catalysts. These catalysts are very active because they allow a dual site mechanism: n-paraffins are dehydrogenated to olefins on the metal, olefins are isomerized on the acid site, and iso-olefins produced are hydrogenated to iso-paraffins on the metal. C. M. Lo ´pez (&)  Y. Guille ´n Facultad de Ciencias, Escuela de Quı ´mica, Centro de Cata ´lisis, Petro ´leo y Petroquı ´mica,, Universidad Central de Venezuela, Apartado 47102, Caracas 1020-A, Venezuela e-mail: cmlopez@ciens.ucv.ve L. Garcı ´a  L. Go ´mez  A ´ . Ramı ´rez Facultad de Ingenierı ´a, Escuela de Ingenierı ´a Quı ´mica, Universidad Central de Venezuela, Apartado 48057, Caracas 1020-A, Venezuela 123 Catal Lett (2008) 122:267–273 DOI 10.1007/s10562-007-9321-4