它是用于生产不饱和醛与被引入含氧气体，分子氧的催化剂通过氧化其中至少元素Mo，铋，磷，0以及含Si的含有活性物质在催化剂体的形式与所述外表面之间的一定比率的载体材料 和容积和限定的空间膨胀，孔隙率，密度，比表面积，压碎强度，耐磨损和使用Gasdurchströmbarkeit。 该催化剂是由特定的生产运行，这也是本发明的主题而获得。

A catalyst for the production of unsaturated aldehydes by oxidation with a molecular oxygen is introduced containing gas, in which an at least the elements Mo, Bi, P and 0 and Si-containing substrate containing active composition in the form of a catalyst body with a certain ratio between the outer surface and volume and a defined spatial extent, porosity, density, specific surface area, breaking strength, abrasion and Gasdurchströmbarkeit used. The catalyst is obtainable by a specific production run, which is also subject matter of the invention.