Abstract:
The invention relates to a method for producing isocyanates by phosgenating the corresponding amines in the gas phase, characterized in that a reaction mixture containing phosgene from the gas-phase synthesis of carbon monoxide and chlorine to form phosgene, the gas-phase synthesis being driven at a stoichiometric excess of carbon monoxide with respect to chlorine, is divided into two streams by means of a thermal separating method and/or a membrane separating method, specifically into a first flow low in carbon monoxide, containing at most 1 wt% of carbon monoxide with respect to the total weight of the first flow low in carbon monoxide, and into a second flow high in carbon monoxide, containing more than 10 wt% of carbon monoxide with respect to the total weight of the second flow high in carbon monoxide, and that the first flow low in carbon monoxide is used as a reactant flow in the phosgenation of amines to form isocyanates in the gas phase.
Abstract:
The invention relates to a reactor (1) for producing phosgene by reacting carbon monoxide and chlorine in the gas phase in the presence of a solid catalyst, which is provided in a plurality of contact tubes (2) which are arranged parallel to each other in the longitudinal direction of the reactor (1) and which are welded into a tube bottom (3) in each case at both ends of said contact tubes, the starting materials being fed at the upper end of the contact tubes (2) and the gaseous reaction mixture being drained at the lower end of the contact tubes (2), through a hood in each case, and having feed and discharge devices for a liquid heat exchanger (7) in the jacket space (4) between the contact tubes (2), the flow of the heat exchanger (7) in the jacket space (4) between the contact tubes (2) being directed in a meandering manner by means of baffle plates (5), in each case a baffle plate (5) leaving open two circular segment-shaped passage openings (6) located opposite of each other at the reactor inner wall, and in each case the directly following baffle plate leaving open a central passage opening (11), which is bounded by two straight lines that are parallel and equidistant to each other and to a reactor diameter, and the reactor (1) having no tubes in the area of the circular segment-shaped passage openings (6) and in the area of the central passage opening (11), characterized in that the plurality of contact tubes (2) oriented parallel to each other in the longitudinal direction of the reactor (1) are arranged in two bundles of contact tubes (2) that are identical to each other and that are separated from each other by an area free of contact tubes that extends along a reactor diameter on both sides, and the heat transfer coefficients at the boundary layer between the contact tubes (2) and the heat exchanger (7) are homogenized over each reactor cross-section in that the flow paths of the heat exchanger (7) in each reactor cross-section, in each case measured from the first to the last contact tube (2) in the flow direction of the heat exchanger (7), are equalized through a changed arrangement of the contact tubes (2).
Abstract:
The invention relates to a method for coating internal fittings in a reactor, except for electrically heatable, at least partly open-cell foams, with a catalytically active material or a precursor therefor. According to said method, aerosol containing the catalytically active material or the precursor therefor as a dispersed phase is provided and is directed through the reactor at a speed which is set in such a way that the dispersed phase of the aerosol deposits on the internal fittings of the reactor.