Abstract: The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (8) and a second distillation unit (10), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether as an intermediate product and diisobutene as a by-product in the etherification unit (3): (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (7), and vaporizing the bottom product (7) if it is withdrawn as a liquid: (c) reacting the vaporous bottom product (7) in the presence of an acidic catalyst

Abstract: The invention relates to a process for decomposing nitrous oxide from a gas stream (1).

Abstract: The invention relates on a process for working-up a nitrous oxide comprising off-gas stream from a production process of adipic acid by decomposing the nitrous oxide contained in the off-gas stream into nitrogen and oxygen in a fixed bed reactor (21) of a N2O decomposition unit (9) at a temperature in the range from 430 to 800° C. to obtain a purified gas, wherein for controlling the N2O decomposition unit (9) a nonlinear model predictive control is used which is based on a reactor model of the fixed bed reactor based on equations of energy transport and species transport for nitrogen, oxygen and N2O.

Abstract: The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (10) and a second distillation unit (12), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether in the etherification unit (3); (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), and the alkyl tert-butyl ether being withdrawn as the bottom product (7); (c) vaporizing the bottom product from the first distillation unit (5) in an evaporator (8) obtaining a vapor stream (9); (d) reacting the vapor stream (9) of step (c) in the presence of an acidic catalyst obtaining isobutene and the primary

Abstract: The invention relates to a process for starting up a plant for removing isobutene from an isobutene-containing C4-hydrocarbon mixture, the plant comprising an etherification unit containing moist acidic ion exchange resin, a first distillation unit, an ether cleavage unit, and a second distillation unit. The invention further relates to a process for shutting down the plant from a stationary operation mode.

Abstract: The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (8) and a second distillation unit (10), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether as an intermediate product and diisobutene as a by-product in the etherification unit (3); (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (7), and vaporizing the bottom product (7) if it is withdrawn as a liquid; (c) reacting the vaporous bottom product (7) in the presence of an acidic catalyst

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