Abstract:
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.
Abstract:
The invention relates to a method for producing isocyanates by reacting primary amines with phosgene in a solvent, the solvent containing a dialkyl carbonate.
Abstract:
The invention relates to a method for the catalytic oxidation of hydrogen chloride with oxygen to form chloride in a fluidized bed method in the presence of a catalyst containing ruthenium on a particulate carrier made of alpha-aluminum oxide having an average particle size of 10 to 200 µm, characterized in that the catalyst carrier has a low surface roughness and can be obtained from a used catalyst, which has been used for at least 500 operating hours in a fluidized bed method.
Abstract:
A method is proposed for producing phosgene by reacting a feed stream (1) obtained by combining and mixing a chlorine feed stream (2) and a carbon monoxide feed stream (3), wherein the carbon monoxide is fed in a stoichiometric excess over chlorine, on contact tubes that are filled with activated-carbon beds, of a reactor R having a bundle of contact tubes, obtaining a product gas mixture (4) that is separated into a liquid, phosgene-containing product stream (5), and also an exhaust gas stream (6) containing carbon monoxide which is ejected via a pressure-retaining valve, and wherein the feed stream (1) is reacted in the reactor R and also the product gas mixture (4) is separated at a pressure in the range from 2.0 to 6.0 bar superatmospheric pressure, which is characterized in that the carbon monoxide excess in the feed steam (1) to the reactor R is controlled by continuously measuring the flow rate and the concentration of carbon monoxide in the exhaust gas stream (6), herefrom, in combination with the continuously determined measured values of the flow rate of the carbon monoxide feed stream (3), the flow rate and the chlorine concentration of the chlorine feed stream (2), the actual value of the carbon monoxide excess in the feed stream (1) to the reactor R is calculated and matched to the theoretical value of the carbon monoxide excess in the feed stream (1) to the reactor R by adapting the flow rate of the carbon monoxide feed stream (3).