摘要:
The invention provides a process for preparing polytetrahydrofuran, tetrahydrofuran copolymers, their monoesters or diesters and the monoesters or diesters of polytetrahydrofuran having a low color number in the presence of a catalyst, which comprises converting crude tetrahydrofuran which has been prepared in a manner per se into pure tetrahydrofuran by distillation, subsequently subjecting the latter to essentially complete hydrogenation and using the high-purity tetrahydrofuran obtained in this way for the polymerization directly after its preparation.
摘要:
The invention provides a process for preparing polytetrahydrofuran, tetrahydrofuran copolymers, their monoesters or diesters and the monoesters or diesters of polytetrahydrofuran having a low color number in the presence of a catalyst, which comprises converting crude tetrahydrofuran which has been prepared in a manner per se into pure tetrahydrofuran by distillation, subsequently subjecting the latter to essentially complete hydrogenation and using the high-purity tetrahydrofuran obtained in this way for the polymerization directly after its preparation.
摘要:
In a process for preparing polytetrahydrofuran, tetrahydrofuran copolymers, diesters or monoesters of these polymers having a low color number, the polymers obtained by cationic polymerization of tetrahydrofuran are hydrogenated in the presence of a macroporous, supported heterogeneous catalyst comprising at least one metal of groups 7 to 10 of the Periodic Table of the Elements as active metal.
摘要:
A process for working up at least partially deactivated polymerization catalysts for the polymerization or copolymerization of THF which are contaminated with the products of the polymerization or copolymerization of THF comprises (a) in a first step, cleaning the polymerization catalyst by treatment with steam at from 80 to 250° C. and a pressure of from 0.5 to 40 bar and, preferably, (b) in a second step, regenerating the clean polymerization catalyst.
摘要:
A method for reliably avoiding backflow in the transport of a liquid under pressure via a transport pipe (1), in which a shut-off device (2) with differential pressure switching is arranged, into a container (3) which is under pressure and which comprises the liquid to be transported and/or another liquid is proposed, wherein a pressure accumulator (4) which is filled with the liquid to be transported up to a certain level and above the liquid level, in direct contact with the liquid to be transported, with an inert gas is arranged in the transport pipe (1) upstream from the shut-off device (2) in the transport direction, the inert gas being provided in the pressure accumulator (4) under an excess pressure and in an amount relative to the container (3) to be filled which are designed so that, in the case of a drop in the pressure in the transport pipe (1), the inert gas ensures a positive pressure difference in the transport pipe (1) to the container (3) over a period which is at least as long as the reaction time of the shut-off device (2) and the shut-off device (2) has an emptying pipe (6) with emptying valve (7).
摘要:
The invention relates to a tube bundle reactor with a flat feed hood. Alternatively, the release hood may also have a flat design. The flat design reduces the heat of reaction which arises in the hood in the case of reaction types which take place not only in the tube bundle (uncatalyzed reactions and reactions with homogeneously distributed catalyst). This greatly suppresses undesired reactions which already take place in the hood owing to accumulated heat, which achieves a higher selectivity in the case of thermally sensitive reactions. In addition, the thermal distribution within the hoods can be controlled precisely.The tube bundle reactor comprises a tube bundle which has a feed end which is connected to a feed hood of the tube bundle reactor, wherein the feed hood is configured in a flat design with a cross-sectional area at the feed end and an internal volume, and the ratio of internal volume to cross-sectional area is less than 0.35 m. The invention is further implemented by means of a process for operating a tube bundle reactor, comprising: introducing a reactant mixture into a tube bundle and converting at least a proportion of the reactant mixture within the tube bundle to a product. The introducing comprises: feeding the reactant mixture into an interior of a feed hood of the tube bundle reactor and passing the reactant mixture on into a feed end of the tube bundle in the form of a fluid stream. The fluid stream has a cross-sectional area on entry into the feed end, and the interior of the feed hood through which the fluid stream flows has an internal volume; where the ratio of internal volume to cross-sectional area is less than 0.35 m.
摘要:
Mixtures of esters of polyalkylpiperidine derivatives, of the formulae I and II ##STR1## in which the proportions of I to II are 95 to 70% by weight and 5 to 30% by weight, are obtained by reacting about 2 mols of a piperidine of the formula III ##STR2## with 0.9 to 1.3 mols of a diester of the formula IV ##STR3## in the melt at between 100.degree. and 145.degree. C., in the presence of an alkali metal amide as a catalyst.The mixtures of esters thus obtained are very suitable as light stabilizers for plastics.
摘要:
The present invention relates to a process for preparing at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group, at least comprising the stages: (a1) oxidation of a composition (A), at least comprising one cyclic olefin with Z cycles and 7 to 16 carbon atoms and at least two C—C double bonds, by means of dinitrogen monoxide to give a composition (A1), (a2) separating off the at least one cyclic olefin with Z cycles and 7 to 16 carbon atoms with at least two C—C double bonds from the composition (A1) in order to obtain a composition (A2), and (b) distillative treatment of the composition (A2) from step (a2) in order to obtain a composition (B), comprising the at least one cyclic compound with Z cycles and 7 to 16 carbon atoms with a keto group and less than 1.0% by weight of the at least one compound with Z−1 cycles and 7 to 16 carbon atoms with at least one aldehyde group, where Z can be 1, 2, 3 or 4.
摘要:
Processes comprising: (a) providing a first reactant comprising a bioethanol; and (b) reacting the first reactant with a second reactant comprising a component selected from the group consisting of ammonia, primary amines, secondary amines and mixtures thereof, in the presence of hydrogen and a catalytically effective amount of a heterogeneous hydrogenation/dehydrogenation catalyst to form an ethylamine; wherein the catalyst has been activated at a temperature of 100 to 500° C. for at least 25 minutes; wherein prior to activation the catalyst comprises: (i) 20 to 65% by weight of a support material comprising one or both of zirconium dioxide (ZrO2) and aluminum oxide (Al2O3), (ii) 1 to 30% by weight of oxygen-comprising compounds of copper, calculated as CuO, and (iii) 21 to 70% by weight of oxygen-comprising compounds of nickel, calculated as NiO; and wherein after activation the catalyst has a CO uptake capacity of >110 μmol of CO/g of the catalyst.