Abstract: A method for detecting deposits in a pipe system of an apparatus is proposed, the apparatus being flowed through by a fluid. In the method it is provided that at least one microwave probe is introduced into the pipe system in such a way that the fluid flows against a window (102) of the microwave probe that is transparent to microwave radiation, and that microwaves are coupled into the pipe system by way of at least one microwave probe, wherein a reflection measurement is carried out with one or two microwave probes, and/or at least two microwave probes are introduced into the pipe system at a distance from one another and a transmission measurement is carried out, wherein a comparison of measurement data with a reference or a previous measurement is used to deduce a constriction in the pipe system segment and the free cross-section at the constriction is determined, the detection of a constriction being used to deduce the presence of deposits.

Abstract: The invention relates to a process for preparing aromatic amines by hydrogenation of corresponding nitroaromatics by means of hydrogen, and also an apparatus suitable for this purpose. In particular, the invention relates to a process for preparing toluenediamine (TDA) by hydrogenation of dinitrotoluene (DNT).

Abstract: A process for a continuous production of a polyetherol first involves reacting a catalyst (5) with an alcohol starter (3) or an alkoxylated precursor, to give a mixture comprising an alcoholate and water. Water is then removed from the mixture. The process further involves feeding the alcoholate into a bubble column and feeding an alkylene oxide into the bottom of a compartment of the bubble column, such that the alkylene oxide rises in the alcoholate. The alkylene oxide then reacts with the alcoholate or a secondary product from the reaction between the alcoholate and alkylene oxide, to give the polyetherol.

Abstract: The invention relates to a process for preparing aromatic amines by hydrogenation of corresponding nitroaromatics by means of hydrogen, and also an apparatus suitable for this purpose. In particular, the invention relates to a process for preparing toluenediamine (TDA) by hydrogenation of dinitrotoluene (DNT).

Abstract: The invention relates to a process for preparing isocyanates and/or polyisocyanates by reacting the corresponding amines with phosgene, optionally in the presence of an inert medium, in a reactor (1), a first reactant stream comprising the amine being supplied to the reactor (1) in liquid form, and a second reactant stream comprising the phosgene being supplied to the reactor in gaseous form. The reactor is a centrifugal reactor (1) having a packing (9) which rotates about a central axis (7) in a housing (13), the first reactant stream and the second reactant stream being supplied to the rotating packing (9) such that the reactant streams are mixed due to the centrifugal force in the rotating packing (9) and are transported outward, the mixing in the rotating packing (9) resulting in reaction of the phosgene with the amine to give the corresponding isocyanate or polyisocyanate.

Abstract: The present invention relates to a reactor for the photocatalytic treatment of liquid or gaseous streams, which reactor comprises a tube through which the stream to be treated flows, wherein, in the tube, there are arranged at least one light source, at least one flat means M1 provided with at least one photocatalytically active material and at least one flat means M2 reflecting the light radiation radiated by the at least one light source, wherein the reflecting surface of the at least one means M2 and the inner wall of the tube are at an angle greater than or equal to 0°, in such a manner that the light exiting from the light source is reflected by the at least one means M2 onto the photocatalytically active material, and to a method for the photocatalytic treatment of liquid or gaseous streams by irradiation with light in the reactor according to the invention.

Abstract: The present invention relates to a process for preparing polyisocyanates comprising biuret groups from diisocyanates or polyisocyanates and diamines.

Abstract: In the process for hydrogenating butadiyne over a catalyst which comprises at least one platinum group metal on an inorganic metal oxide as a support, the hydrogenation is performed at a pressure in the range from 1 to 40 bar and a temperature in the range from 0 to 100° C., and from 0.05 to 5% by weight, based on the overall catalyst, of platinum group metal is present on the support.

Abstract: The invention relates to a process for preparing isocyanates and/or polyisocyanates by reacting the corresponding amines with phosgene, optionally in the presence of an inert medium, in a reactor (1), a first reactant stream comprising the amine being supplied to the reactor (1) in liquid form, and a second reactant stream comprising the phosgene being supplied to the reactor in gaseous form. The reactor is a centrifugal reactor (1) having a packing (9) which rotates about a central axis (7) in a housing (13), the first reactant stream and the second reactant stream being supplied to the rotating packing (9) such that the reactant streams are mixed due to the centrifugal force in the rotating packing (9) and are transported outward, the mixing in the rotating packing (9) resulting in reaction of the phosgene with the amine to give the corresponding isocyanate or polyisocyanate.

Abstract: A process for a continuous production of a polyetherol first involves reacting an alcohol with a starter or an alkoxylated precursor, to give a mixture comprising an alcoholate and water. Water is then removed from the mixture. The process further involves feeding the alcoholate into a bubble column and feeding an alkylene oxide into the bottom of a compartment of the bubble column, such that the alkylene oxide rises in the alcoholate. The alkylene oxide then reacts with the alcoholate or a secondary product from the reaction between the alcoholate and alkylene oxide, to give the polyetherol.

Abstract: The present invention relates to a process for preparing polyisocyanates comprising biuret groups from diisocyanates or polyisocyanates and diamines.

Abstract: The present invention relates to a reactor for the photocatalytic treatment of liquid or gaseous streams, which reactor comprises a tube through which the stream to be treated flows, wherein, in the tube, there are arranged at least one light source, at least one flat means M1 provided with at least one photocatalytically active material and at least one flat means M2 reflecting the light radiation radiated by the at least one light source, wherein the reflecting surface of the at least one means M2 and the inner wall of the tube are at an angle greater than or equal to 0°, in such a manner that the light exiting from the light source is reflected by the at least one means M2 onto the photocatalytically active material, and to a method for the photocatalytic treatment of liquid or gaseous streams by irradiation with light in the reactor according to the invention.

Abstract: The invention relates to a process for preparing reactive zinc by electrochemical reduction, wherein iron or steel is used as cathode material.

Abstract: In the process for hydrogenating butadiyne over a catalyst which comprises at least one platinum group metal on an inorganic metal oxide as a support, the hydrogenation is performed at a pressure in the range from 1 to 40 bar and a temperature in the range from 0 to 100° C., and from 0.05 to 5% by weight, based on the overall catalyst, of platinum group metal is present on the support.