Anna Escofet Roig

Prospects of Fe/MCM‐41 as a Catalyst for Hydrocarbon Synthesis

We report the synthesis of cylindrical nanoparticles of metallic Fe entirely included in MCM‐41 pores. Their dimensions are approx.3 nm diameter and approx. 3.8 nm length. We show that a coherent analysis of the results yielded by the various techniques is essential to obtain a catalyst supported on an MCM‐41 matrix of ≈ 3 nm average pore diameter, which is active and selective toward olefins. The solids were characterized by low‐angle x‐ray diffraction, high‐resolution transmission electron microscopy, high‐resolution scanning transmission electron microscopy equipped with a high‐angle annular dark‐field, CO chemisorption, volumetric oxidation, and Mossbauer spectroscopy (in controlled atmosphere for the reduced catalysts). Catalytic results in the Fischer‐Tropsch synthesis, as well as some unexpected results —like the inhomogeneous pore filling and discontinuous Fe particles— are also discussed.

Highly stable solid state dye lasers based on polymer-filled nanoporous silica aerogels

New hybrid matrices based on silica aerogels obtained under supercritical conditions, a highly porous material with porosityt up to 90%, have been synthesized. The open porous network of the aerogel was saturated with pyrromethene dyes solved in organic mooners, and polymerization took place inside of the silica structure. The resulting polymer filled nanoporous aerogels, cast in the form of cylindrical monoliths, were used as gain media in solid-state dye lasers. Under the demanding conditions of tightly focused transversal pumping with 532 nm, 5 mJ pulses at 10 Hz repetition rate, highly photostable laser emission was obtained.