Abstract: The present invention relates to silver-containing and optionally promoter-containing supported catalysts and catalyst intermediates, processes for their preparation and their use for preparing alkylene oxides by oxidation of alkenes with oxygen. The catalysts are prepared by treatment of a support with a lactic acid containing silver ions, nitrate ions and optionally promoter metal ions, drying, predecomposition in a virtually oxygen-free atmosphere and subsequent activation by heating in an oxygen-containing atmosphere while precisely controlling the temperature conditions and the feeding-in of oxygen. The catalyst intermediates obtainable by treatment, drying and only predecomposition can be activated in a temporally and physically separate process step to form the actual catalysts. Suitable promoters are alkaline earth metal compounds and/or alkali metal compounds. High activities and high selectivities are achieved when using the catalysts of the invention for preparing alkylene oxides.

Abstract: C.sub.4 -C.sub.6 -alkenes having an internal double bond can be produced by hydroisomerization of C.sub.4 -C.sub.6 -alkenes having a terminal double bond in the presence of H.sub.2 on a catalyst having a content of a noble metal of group VIII of the Periodic Table of the Elements (Mendeleev), if C.sub.4 -C.sub.6 -alkenes having a terminal double bond are fed into a hydroisomerization reactor after preheating, as such or in a mixture with other hydrocarbons, and the reaction product is divided into a work-up stream and a recycle stream. The recycle stream is recycled to the inlet of the hydroisomerization reactor and is used there as feed together with the C.sub.4 -C.sub.6 -alkenes having a terminal double bond or with the hydrocarbon stream comprising the C.sub.4 -C.sub.6 -alkenes having a terminal double bond and with the H.sub.2.