caa a22 4500 463189620 CHVBK 20180406164905.0 cr unu---uuuuu 170326e20071001xx s 000 0 eng 10.1007/s10973-007-8476-y doi (NATIONALLICENCE)springer-10.1007/s10973-007-8476-y Delmon B. CATA, Université Catholique de Louvain, Place Croix du Sud 2/17, 1348, Louvain-la-Neuve, Belgium aut Preparation of heterogeneous catalysts [Elektronische Daten] Synthesis of highly dispersed solids and their reactivity [B. Delmon] The preparation of heterogeneous catalysts has been for many years a dynamic field of sub-nanotechnology and remains so nowadays. The approach to preparation must be examined in function of the specific demands concerning (i) activity and (ii) selectivity, that both depend on the arrangement of atoms at a scale smaller than 0.02 nm. Adequate access of reactants to the surface must be provided. Most catalysts are used in the form of pellets or cylinders obtained by pressing, extrusion or other techniques. This implies a control of texture at dimension scales extending from a fraction of a nanometer to several millimetres (and sometimes more). A third demand (iii) is resistance to ageing. In particular, stability at relatively high temperatures is necessary. The strategy adopted in the majority of cases is to start from a material that is homogeneous in composition at the Angström scale, generally a liquid or a solid of complex composition, frequently amorphous. A general objective is to locate the different constituting atoms at precise positions. The main difficulty is to transform the starting precursor into a highly porous solid without segregation of different elements that would produce tiny parts with different properties. The specific approach to catalyst preparation is based on the general concepts used for controlling the reactivity of solids. Typical methods of general use will be examined. Chemical bonds of practically any kind can retain the elements constituting the future catalyst at the position they have in the precursor. The so-called ‘citrate process' and its variants are of wide application. More elaborate approaches start from molecules or polymers associating the necessary elements. Springer Science+Business Media, LLC., 2007 catalyst preparation nationallicence citrate method nationallicence diffusion in solids nationallicence mixed oxide catalysts nationallicence multi-component precursors nationallicence prevention of nucleation nationallicence reactivity of solids nationallicence segregation in solids nationallicence Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 49-65 1388-6150 90:1<49 2007 90 10973 https://doi.org/10.1007/s10973-007-8476-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-007-8476-y text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Delmon B. CATA, Université Catholique de Louvain, Place Croix du Sud 2/17, 1348, Louvain-la-Neuve, Belgium aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/1(2007-10-01), 49-65 1388-6150 90:1<49 2007 90 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer