Abstract: A process for the preparation of polyisocyanates containing iminooxadiazinedione groups, comprising reacting at least one (cyclo)aliphatic diisocyanate in the presence of at least one oligomerization catalyst, and when the reaction has reached a predeterminable degree of conversion, based on the (cyclo)aliphatic diisocyanates, stopping the reaction by addition of at least one catalyst poison for the oligomerization catalyst, wherein the oligomerization catalyst is a salt containing a fluoride or poly(hydrogen)fluoride [F?×(HF)m] as anion and the catalyst poison is a solution containing at least one alcohol comprising at least 6 carbon atoms as solvent and wherein m is a number between 0.01 and 20.

Abstract: Polyisocyanate composition containing (A) at least one polyisocyanate obtainable by reacting at least one monomeric isocyanate, (B) at least one solvent containing a mixture of C7-C14 aromatic hydrocarbons, (C) optionally at least one further solvent, (D) optionally at least one Lewis-acidic organic metal compound capable of accelerating the reaction of isocyanate groups with isocyanate-reactive groups, (E) optionally other coatings additives, wherein the amount of cumene in component (B) is less than 1 wt %, preferably less than 0.7 wt %.

Abstract: The present invention relates to a new process for preparing polyisocyanates containing isocyanurate groups and being flocculation-stable in solvents from (cyclo)aliphatic diisocyanates.

Abstract: The present invention relates to a novel process for preparing isocyanurate-comprising polyisocyanates of (cyclo)aliphatic diisocyanates that are especially stable to color drift in solvents.

Abstract: The present invention relates to a new process for preparing polyisocyanates containing isocyanurate groups and being flocculation-stable in solvents from (cyclo)aliphatic diisocyanates.

Abstract: The present invention relates to a novel process for preparing isocyanurate-comprising polyisocyanates of (cyclo)aliphatic diisocyanates that are especially stable to color drift in solvents.

Abstract: A method for treating contaminated liquids in a flow by ozone, wherein the ozone is fed in gas form into the flow at one point and then is mixed into the flow in stages by mixers following one another in the flow direction, so that an absolute quantity of introduced ozone increases after each mixer until a feed efficiency of more than 95 percent is reached.

Abstract: A method for treating contaminated liquids in a flow by ozone, wherein the ozone is fed in gas form into the flow at one point and then is mixed into the flow in stages by mixers following one another in the flow direction, so that an absolute quantity of introduced ozone increases after each mixer until a feed efficiency of more than 95 percent is reached.

Abstract: A method for the determination of the radical scavenging potential of a water, and includes determining the degradation of at least one reference substance in the water as a result of irradiation with UV light of at least one wavelength in the range of 100 to 350 nm, and a device for carrying out such determination with the aim of controlling a process for the oxidative treatment of water.

Abstract: A process is described for preparing 3-pentenenitrile, characterized by the following process steps: (a) isomerizing a reactant stream which comprises 2-methyl-3-butenenitrile over at least one dissolved or dispersed isomerization catalyst to give a stream 1 which comprises the at least one isomerization catalyst, 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, (b) distilling stream 1 to obtain a stream 2 as the top product which comprises 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, and a stream 3 as the bottom product which comprises the at least one isomerization catalyst, (c) distilling stream 2 to obtain a stream 4 as the top product which, compared to stream 2, is enriched in (Z)-2-methyl-2-butenenitrile, based on the sum of all pentenenitriles in stream 2, and a stream 5 as the bottom product which, compared to stream 2, is enriched in 3-pentenenitrile and 2-methyl-3-butenenitrile, based on the sum of all pentenenitriles in stream 2, (d) dis

Abstract: A process is described for preparing 3-pentenenitrile, characterized by the following process steps: (a) isomerizing a reactant stream which comprises 2-methyl-3-butenenitrile over at least one dissolved or dispersed isomerization catalyst to give a stream 1 which comprises the at least one isomerization catalyst, 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, (b) distilling stream 1 to obtain a stream 2 as the top product which comprises 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile, and a stream 3 as the bottom product which comprises the at least one isomerization catalyst, (c) distilling stream 2 to obtain a stream 4 as the top product which, compared to stream 2, is enriched in (Z)-2-methyl-2-butenenitrile, based on the sum of all pentenenitriles in stream 2, and a stream 5 as the bottom product which, compared to stream 2, is enriched in 3-pentenenitrile and 2-methyl-3-butenenitrile, based on the sum of all pentenenitriles in stream 2, (d) dis

Abstract: A method for the determination of the radical scavenging potential of a water, and includes determining the degradation of at least one reference substance in the water as a result of irradiation with UV light of at least one wavelength in the range of 100 to 350 nm, and a device for carrying out such determination with the aim of controlling a process for the oxidative treatment of water.

Abstract: Process for working up an exhaust gas from a system for producing hydroxylamine or hydroxylammonium salts by catalytic reduction of nitrogen monoxide with hydrogen, the exhaust gas containing nitrogen monoxide, hydrogen, dinitrogen monoxide, nitrogen and ammonia. At least some of the hydrogen present in the exhaust gas is separated off from the exhaust gas by means of a gas-tight membrane-electrode assembly which comprises at least one selectively proton-conducting membrane, a retentate side, a permeate side, and, on each side of the membrane, at least one electrode catalyst, wherein, on the retentate side of the membrane, at least some of the hydrogen is oxidized to protons at the anode catalyst and the protons, after crossing the membrane, are, on the permeate side, at the cathode catalyst according to (I) reduced to hydrogen and/or (II) reacted with oxygen to form water, the oxygen originating from an oxygen-containing stream which is contacted with the permeate side.

Abstract: A process for long-term operation of a continuous heterogeneously catalyzed partial dehydrogenation of a hydrocarbon to be dehydrogenated, in which a reaction gas mixture stream comprising the hydrocarbon to be dehydrogenated in a molar starting amount KW is conducted through an overall catalyst bed comprising the total amount M of dehydrogenation catalyst and the deactivation of the overall catalyst bed is counteracted in such a way that, with increasing operating time, the contribution to the conversion in the first third of the total amount M of dehydrogenation catalyst in flow direction decreases, the contribution to the conversion in the last third of the total amount M of dehydrogenation catalyst in flow direction increases, and the contribution to the conversion in the second third of the total amount M of dehydrogenation catalyst in flow direction passes through a maximum.

Abstract: A device and a method for treating liquids by ozone, including a pipe in which a main flow of the liquid is guided in a flow direction from an inlet to an outlet, an ozone feed point at which ozone can be introduced in gas form into the main flow, and at least two mixers which are located downstream of the ozone feed point, wherein the mixers are arranged at a distance from one another, and wherein at least one reaction zone is formed between the mixers, and wherein the mixers are designed in such a way that they each dissolve only a portion of the ozone in the main flow that has been introduced in gas form.

Abstract: A process for working up an exhaust gas A from a system for producing hydroxylamine or hydroxylammonium salts by catalytic reduction of nitrogen monoxide with hydrogen, wherein the exhaust gas A comprises nitrogen monoxide, hydrogen, dinitrogen monoxide, nitrogen and ammonia, and at least some of the hydrogen present in the exhaust gas A is separated off from the exhaust gas A by means of a gas-tight membrane-electrode assembly which comprises at least one selectively proton-conducting membrane, a retentate side, a permeate side, and, on each side of the membrane, at least one electrode catalyst, wherein, on the retentate side of the membrane, at least some of the hydrogen is oxidized to protons at the anode catalyst and the protons, after crossing the membrane, are, on the permeate side, at the cathode catalyst according to I reduced to hydrogen and/or II reacted with oxygen to form water, wherein the oxygen originates from an oxygen-comprising stream O which is contacted with the permeate side.

Abstract: A method for producing 3-pentenenitrile is provided that includes: (a) isomerizing an educt stream containing 2-methyl-3-butenenitrile on at least one dissolved or dispersed isomerization catalyst to form a stream (1), which contains the isomerization catalyst(s), 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile; (b) distilling the stream (1) to obtain a stream (2) as the overhead product, which contains 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile and a stream (3) as the bottom product, which contains the isomerization catalyst(s); (c) distilling the stream (2) to obtain a stream (4) as the overhead product, which is enriched with (Z)-2-methyl-2-butenenitrile in comparison to stream (2), and a stream (5) as the bottom product, which is enriched with 3-pentenenitrile and 2-methyl-3-butenenitrile in comparison to stream (2); (d) distilling stream (5) to obtain a stream (6) as the bottom product, which contains 3-pentenenitrile and a stream (7) as the he

Abstract: A process is described for separating mixtures of isomeric pentenenitriles, in which at least one isomer is removed from the mixture, wherein the separation of the substance mixtures of isomeric pentenenitriles is effected distillatively under reduced pressure.

Abstract: A method for producing 3-pentenenitrile is provided that includes: (a) isomerizing an educt stream containing 2-methyl-3-butenenitrile on at least one dissolved or dispersed isomerisation catalyst to form a stream (1), which contains the isomerisation catalyst(s), 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile; (b) distilling the stream (1) to obtain a stream (2) as the overhead product, which contains 2-methyl-3-butenenitrile, 3-pentenenitrile and (Z)-2-methyl-2-butenenitrile and a stream (3) as the bottom product, which contains the isomerisation catalyst(s); (c) distilling the stream (2) to obtain a stream (4) as the overhead product, which is enriched with (Z)-2-methyl-2-butenenitrile in comparison to stream (2), and a stream (5) as the bottom product, which is enriched with 3-pentenenitrile and 2-methyl-3-butenenitrile in comparison to stream (2); (d) distilling stream (5) to obtain a stream (6) as the bottom product, which contains 3-pentenenitrile and a stream (7) as the he

Abstract: An process for preparing 3-pentenenitrile by hydrocyanating 1,3-butadiene, in which the process yield with regard to recycled 1,3-butadiene is maximized.