Group 6 metal oxide-carbon aerogels. Their synthesis, characterization and catalytic activity in the skeletal isomerization of 1-butene Carlos Moreno-Castilla a,* , Francisco Jose  Maldonado-Ho Âdar a , Jose  Rivera-Utrilla a , Enrique Rodrõ Âguez-Castello Ân b a Grupo de Investigacio Ân en Carbones, Departamento de Quõ Âmica Inorga Ânica, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain b Departamento de Quõ Âmica Inorga Ânica, Universidad de Ma Âlaga, Ma Âlaga, Spain Received 11 December 1998; received in revised form 1 March 1999; accepted 5 March 1999 Abstract Group 6 metal±organic aerogels were prepared by polymerization of a resorcinol±formaldehyde mixture which contained metallic salts of the elements of this group. The aerogels prepared were carbonized both at 773 and 1273 K to obtain the corresponding metal oxide±carbon aerogels. All these materials were characterized by different techniques including gas adsorption, mercury porosimetry, XRD, XPS and decomposition of isopropanol to determine their textural characteristics, state of the metallic phase and surface acidity, respectively. The metal oxide±carbon aerogels were tested in the isomerization reaction of 1-butene. The most active catalyst was the tungsten oxide±carbon aerogel pretreated at 773 K, which presented an isobutene yield of 40% at 448 K. This was due to its high surface acidity and more adequate porosity. Isobutene and trans-2-butene were the main reaction products obtained and no C 3 ±C 5 and C 2 ±C 6 by-products were observed. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Organic aerogels; Metal oxide±carbon aerogels; 1-Butene isomerization 1. Introduction Organic aerogels have been synthesized recently following Pekala's method to prepare aerogels by polycondensation of certain organic monomers [1± 11]. Carbon aerogels and activated carbon aerogels can be obtained from the corresponding organic aero- gels by carbonization and activation [8±11]. These materials present very large meso- and microporosity. Very recently [11,12], we demonstrated that transi- tion-metal-containing carbon aerogels can also be prepared by adding the adequate metallic salt to the original recipe of the aerogel. The textural character- istics of these materials depended on the nature of the metal. Thus, whereas the sample containing a very small amount of Pt had the largest meso- and macro- pore volume (0.822 and 2.982 cm 3 g 1 ), those con- taining either Pd or Ag were essentially microporous. Hence, metal±carbon aerogels are very new materials which, due to their method of synthesis, can provide the metal dispersed inside a carbon matrix with a very well developed porosity. This could, therefore, be a Applied Catalysis A: General 183 (1999) 345±356 *Corresponding author. Tel.: +34-958-243323; fax: +34-958- 248526; e-mail: cmoreno@goliat.ugr.es 0926-860X/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII:S0926-860X(99)00068-X