摘要:
The invention relates to a method of measuring entry of water and resulting corrosion in plants for producing isocyanates by reacting phosgene with one or more primary amines in a solvent. The invention further relates to an apparatus for producing such isocyanates, in the work-up section of which probes for monitoring corrosion are arranged in defined places.
摘要:
The present invention accordingly provides a process for preparing light-coloured polyphenylene-polymethylene polyisocyanates comprising the steps (a) providing an amount of chlorine, (b) separating the chlorine provided in the step (a) to obtain a first chlorine fraction having a content of free and bound bromine and iodine of
摘要:
The present invention relates to a process for the production of isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), by reacting an amine with phosgene in the liquid phase or in the gas phase to form the corresponding isocyanates, subsequent removal of the solvent in at least two steps to obtain at least two solvent streams, individual treatment of the at least two solvent streams, and re-circulation of at least a portion of the solvent streams.
摘要:
A process for preparing polyoxymethylene dialkyl ethers of the formula H2m+1CmO(CH2O)nCmH2m+1 where n=2-10, m, identically or differently,=1 or 2, in which a dialkyl ether selected from dimethyl ether, methyl ethyl ether and diethyl ether, and trioxane are fed into a reactor and reacted in the presence of an acidic catalyst, the amount of water introduced into the reaction mixture by the dialkyl ether, trioxane and/or the catalyst being
摘要:
A process for preparing polyoxymethylene dimethyl ether of the formula H3CO(CH2O)nCH3 where n=2-10, in which methylal and trioxane are fed into a reactor and reacted in the presence of an acidic catalyst, wherein the amount of water introduced into the reaction mixture by methylal, trioxane and/or the catalyst is 4 are recycled into the reaction.
摘要:
In a process for drying microporous, fluid-containing particles, the fluid-containing particles to be dried are fed as a moving bed countercurrently to a drying fluid, the interfacial tension of the fluid being reduced in comparison with the interfacial tension of the fluid at room temperature, at near-critical to supercritical pressure of the fluid, preferably to a value in the range from 0 to {fraction (1/10)}, in particular from 0 to {fraction (1/20)}, of the interfacial tension at room temperature. Furthermore, microporous, three-dimensionally networked particles are prepared by a process comprising preparation of microporous particles containing pore liquid, exchange of the pore liquid in the particles for a fluid and drying of the fluid-containing particles, the exchange and drying being carried out in the moving bed by the countercurrent method.
摘要:
In a process for drying microporous, fluid-containing particles, the heat required for increasing the temperature is supplied by convection by reducing the interfacial tension of the fluid, preferably to 0 to 1/10, in particular to 0 to 1/20, of the interfacial tension of the fluid at room temperature, by appropriately increasing the temperature at from close to the critical pressure to supercritical pressure of the fluid. Furthermore, microporous, three-dimensionally networked particles are prepared by a process in which the drying process is used. In addition, an apparatus is used for carrying out the drying process, the apparatus comprising a pressure container having an inner container and pressure-withstanding outer container and suitable measuring and control apparatuses and pump apparatuses and heat exchangers, the inner container being provided for holding the particles to be dried and a gap being provided between the inner container and the outer container.
摘要:
A process for preparing phosgene by reaction of a feed stream (1) obtained by combining and mixing a chlorine feed stream (2) and a carbon monoxide feed stream (3), with the carbon monoxide being introduced in a stoichiometric excess over chlorine, in catalyst tubes filled with beds of activated carbon in a reactor R having a bundle of catalyst tubes,to give a product gas mixture (4)which is separated into a liquid, phosgene-comprising product stream (5) and an offgas stream (6) comprising carbon monoxide which is discharged via a pressure-regulating valve, where the reaction of the feed stream (1) in the reactor R and the separation of the product gas mixture (4) are carried out under a pressure in the range from 2.0 to 6.0 bar gauge pressure, whereinthe excess of carbon monoxide in the feed stream (1) to the reactor R is regulated by continuously measuring the flow and the concentration of carbon monoxide in the offgas stream (6), calculating the actual value of the excess of carbon monoxide in the feed stream (1) to the reactor R from these measurements in combination with the continuously measured values for the flow of the carbon monoxide feed stream (3) and the flow of and the chlorine concentration in the chlorine feed stream (2) and matching this to the intended value of the excess of carbon monoxide in the feed stream (1) to the reactor R by adapting the flow of the carbon monoxide feed stream (3), is proposed.
摘要:
The present invention relates to a process for the production of isocyanates, preferably diisocyanates and polyisocyanates of the diphenylmethane series (MDI), by reacting an amine with phosgene in the liquid phase or in the gas phase to form the corresponding isocyanates, subsequent removal of the solvent in at least two steps to obtain at least two solvent streams, individual treatment of the at least two solvent streams, and recirculation of at least a portion of the solvent streams.