Surface Properties and Catalysis by Non-Metals [antikvár]

FOREWORD In the field of heterogeneous catalysis, it is convenient to distinguish, in a perfectly unjustified and over--simplified way. between metal catalysts, and the other catalysts. The first are easy to define : they are those in which a reduced metal is the active phase. It is thus easy to circumscribe, by exclusion, the other class namely the "non-metals". We have adopted this definition for the sake of our colleagues working on catalysis by metals, and to avoid a lengthy title like "surface properties and catalysis by transition metal oxides, sulfides, carbides, nitriles, etc . ,." . Defined in this manner, non-metal catalysts represented, in 1980, 84 wt. % of the industrial heterogeneous catalysts. To be more specific, this proportion corresponds to catalysts which, under the working conditions in the industrial plant, contain their catalytically active metallic elements in a non-reduced state. It should however be recalled that most metal catalysts are supported on oxides, which, often, represent over 90% (sometimes 99,4% in the case of the platinum reforming catalysts) of the total weight. The value of non-metal catalysts represents 57% of the total market. If we exclude the first heterogeneous catalyst in importance, namely that for catalytic cracking, the remaining non-metal catalysts account for over a third, in value, of the heterogenous catalysts together. The fastest growing group (predicted rate : about 13% per year) of catalysts is that of the hydrotreatment catalysts, whose active phase is constituted of sulfides. The oxide catalysts used for oxidation and ammoxi-dation also offer fascinating perspectives of growth. Non-metal catalysts are the key to the efficient use of natural resources, e.g. by making valuable products out of "bottom of the barrel" feeds (catalytic cracking, hydrotreat-ments), or by producing with continuously increasing selectivity the building blocks necessary to petrochemistry (selective oxidation and ammoxidation). J. P. Bonnelle et al. feds.J, Surface Properties and Catalysis by Non-Metals, vii-xiii. Copyright © 1983 by D. Reidel Publishing Company.