Abstract: Process and catalyst for dehydrogenation or dehydrocyclization of hydrocarbons. The catalyst consists of an aluminum oxide/chromium oxide support with promotors consisting of compounds of alkali metals and/or alkaline earth metals and compounds of metals from the third and/or fourth subgroups of the periodic table. Coke formation and side reactions can be substantially suppressed by the use of these catalysts under special operating conditions and special reactors.

Abstract: Carrier supported catalysts are prepared, comprising metal ions which in their most stable state occur as anions or as higher-valency cations which exhibit a poor interaction with the support material by deposition-precipitation through increasing the hydroxyl ion concentration in homogeneous solution. According to the invention, prior to deposition-precipitation the metal ions are electrochemically reduced to soluble metal ions having a lower valency. Preferably, the pH value of a suspension of the support to be loaded in a solution of the electrochemically reduced metal ions is homogeneously increased by hydrolysis of compounds such as urea or isocyanate, or by the controlled injection of an alkaline solution below the surface of the suspension.