The present invention relates to a process for preparing C.sub.4-C.sub.15 lactams, in which a C.sub.1-C.sub.10-alkyl nitrite is reacted with a C.sub.4-C.sub.15-cycloalkane and is illuminated with a light-emitting diode during the reaction. This forms a C.sub.4-C.sub.15-cyclohexanone oxime which is then converted further to a C.sub.4-C.sub.15 lactam; the C.sub.1-C.sub.10 alcohol formed is recycled into the preparation of the C.sub.1-C.sub.10-alkyl nitrite.

A homogeneous catalyst system is removed from a reaction mixture of two liquid phases by separating the two liquid phases with a membrane having at least one separation-active layer in such a way that the homogeneous catalyst system is at least partially concentrated in a membrane retentate; wherein the reaction mixture contains at least one partially epoxidized cyclic unsaturated compound having twelve carbon atoms; and wherein the membrane separation-active layer contains crosslinked a silicone acrylate and/or polydimethylsiloxane and/or polyimide.

An apparatus for the epoxidation of a cyclic unsaturated C.sub.12 compound with hydrogen peroxide is provided. The apparatus includes a reactor for carrying out the reaction, wherein the walls of the reactor are at least partially furnished with a separation-active layer of crosslinked silicone acrylates and/or polydimethylsiloxane.

An apparatus for the epoxidation of a cyclic unsaturated C.sub.12 compound with hydrogen peroxide is provided. The apparatus includes a reactor for carrying out the reaction, wherein the walls of the reactor are at least partially furnished with a separation-active layer of crosslinked silicone acrylates and/or polydimethylsiloxane.

In a process for oxidizing a feed comprising cyclohexylbenzene, the feed is contacted with oxygen and an oxidation catalyst in a plurality of reaction zones connected in series, the contacting being conducted under conditions being effective to oxidize part of the cyclohexylbenzene in the feed to cyclohexylbenzene hydroperoxide in each reaction zone. At least one of the plurality of reaction zones has a reaction condition that is different from another of the plurality of reaction zones. The different reaction conditions may include one or more of (a) a progressively decreasing temperature and (b) a progressively increasing oxidation catalyst concentration as the feed flows from one reaction zone to subsequent reaction zones in the series.

In a process for oxidizing a feed comprising cyclohexylbenzene, the feed is contacted with oxygen and an oxidation catalyst in a plurality of reaction zones connected in series, the contacting being conducted under conditions being effective to oxidize part of the cyclohexylbenzene in the feed to cyclohexylbenzene hydroperoxide in each reaction zone. At least one of the plurality of reaction zones has a reaction condition that is different from another of the plurality of reaction zones. The different reaction conditions may include one or more of (a) a progressively decreasing temperature and (b) a progressively increasing oxidation catalyst concentration as the feed flows from one reaction zone to subsequent reaction zones in the series.

This invention relates to a process for co-producing cyclohexanol and alkanol, including a cyclohexene esterification step and a cyclohexyl ester hydrogenation step. This invention further relates to a process for further producing cyclohexanone or caprolactam, starting from the co-producing process, and an apparatus for co-producing cyclohexanol and alkanol. The process for co-producing cyclohexanol and alkanol of this invention is environment-friendly, with low production cost and highly improved atom economy.