Abstract: Isocyanates or isocyanate mixtures which are substantially free of color-imparting components are made by treating the isocyanate with hydrogen in the presence of a catalyst at a pressure of from about 3 to about 150 bar, a temperature of from about 100 to about 180.degree. C. for from about 15 minutes to about 4 hours. These isocyanates are particularly useful for the preparation of light-colored polyurethane rigid foams.

Abstract: Aromatic amines are produced by catalytic hydrogenation of corresponding aromatic nitro compounds in the gas phase, by carrying out the hydrogenation in the presence of catalysts which, besides palladium, vanadium and lead, contain in addition molybdenum, tungsten and/or rhenium on a ceramic support having a BET surface area of less than 40 m.sup.3 /g, at temperatures of from 180.degree. C. to 500.degree. C. in a catalyst bed and in a molar ratio of hydrogen to the nitro group or nitro groups of 3:1 to 30:1.

Abstract: A process for the production of aromatic amines by catalylic hydrogenation.

Abstract: A mixer-reactor for mixing at least two fluid substances and carrying out or initiating a reaction between them, wherein the mixer-reactor consists of a substantially rotationally symmetrical casing containing a mixing chamber having separate inlets for the at least two substances and an outlet, the inlet for the at least first substance being provided within the axis of the mixing chamber and the inlet for the at least second substance being constructed in the form of a plurality of nozzles arranged rotationally symmetrically to the axis of the mixing chamber, characterized in that a bolt which is displaceable in the direction of the nozzle axis is allocated to each nozzle, wherein the bolt is acting to remove the caking or clogging material from the nozzle.

Abstract: Isocyanates or isocyanate mixtures which contain no appreciable amounts of color causing materials are produced by phosgenating the amine corresponding to the desired isocyanate and treating the isocyanate-containing phosgenation mixture with hydrogen in the presence of a supported catalyst. The supported catalyst is in a form such that its shortest dimension is from about 0.3 to about 3.0 mm. This catalyst has a BET surface of from about 0.5 to about 150 m.sup.2 /g. No alkali material can be present in the catalyst. These isocyanates are particularly useful for the production of light-colored foams.

Abstract: A process for production of polyamines of the diphenylmethane series through a condensation reaction of aniline with formaldehyde in the presence of an acid catalyst, neutralization of the acid catalyst after reaction completion, and distillation of the resultant polyamine mixture is described. The key feature of the process is the abrupt increase in reaction temperature after the condensation reaction or after the first rearrangement step.