Abstract: A process for preparing nitric acid by: catalytically oxidizing ammonia, to obtain a gas mixture containing NO and O2; cooling and condensing the gas mixture, thereby further oxidizing NO with O2, to obtain a gas stream containing NO2/N2O4 and an aqueous solution containing nitric acid; and countercurrently absorbing the NO2/N2O4 from the gas stream in an absorber with process water (H2O), to obtain nitric acid and an NOx-containing absorber offgas, wherein the water content of the nitric acid is regulated to a concentration in the range from 50 to 77.8% by weight and the NOx content of the absorber offgas to a concentration in the range from 20 to 500 ppm, by continuously measuring the water content of the process air supplied to the catalytic gas phase oxidation and, as a function of this, adjusting the amount of process water (Q-H2O) fed to the absorber.

Abstract: Process for purifying and cooling a gas stream comprising a dialkyl ester A) of an aromatic dicarboxylic acid, which comprises treating the gas stream with an aliphatic dihydroxy compound B) at a temperature less than/equal to the melting point of the dialkyl ester A) in a 1st stage and treating the gas stream with an aliphatic dihydroxy compound B) at above the melting point of the dihydroxy compound B) in at least one 2nd stage.

Abstract: The present invention relates to a process for separating off carbon dioxide from gas mixtures by absorption using aqueous alkaline solutions, which comprises carrying out the absorption in a countercurrent flow apparatus in which the gas mixture which is to be worked up and the aqueous alkaline solution used are passed in countercurrent flow and wherein a discontinuous liquid phase forms in the interior of the countercurrent flow apparatus and the separation is carried out in the interior of the countercurrent flow apparatus in the presence of activated carbon, wherein the activated carbon is present in the interior of the countercurrent flow apparatus in an amount of 1 g to 2 kg of activated carbon per m3 of volume of the countercurrent flow apparatus.

Abstract: What is proposed is a process for preparing nitric acid with a concentration in the range from 50 to 77.8% by weight by catalytic gas phase oxidation of ammonia (1) with a superstoichiometric proportion of process air (2) to obtain a gas mixture (3) comprising NO and O2, cooling/condensation of the gas mixture (3) comprising NO and O2, in the course of which NO is oxidized further by O2 to NO2/N2O4 to obtain an aqueous solution (4) comprising nitric acid and a gas stream (5) comprising NO2/N2O4 and countercurrent absorption of the NO2/N2O4 from the gas stream (5) comprising NO2/N2O4 in process water (H2O) in an absorber (A) to obtain the nitric acid (7) with a concentration in the range from 50 to 77.8% by weight and an NOx comprising absorber offgas (6), wherein the water content of the nitric acid (7) is regulated to a concentration in the range from 50 to 77.

Abstract: The present invention relates to a process for purifying a gas mixture comprising dinitrogen monoxide and to the use of a gas mixture purified in this way as an oxidant for olefins. In a further embodiment, the present invention also relates to a process for preparing ketones comprising the oxidation of an olefin with a gas mixture which has been purified in accordance with the invention and comprises dinitrogen monoxide.

Abstract: A process is proposed for reducing the aerosol-related discharge from a separation column (1) in which one or more components are separated off from a gaseous or liquid starting mixture (G) at actively separating internals (2), aerosols being present or formed in a gas phase, which comprises the actively separating internals (2) being segmented at one or more separation points, which are determined in such a manner that the aerosols have at least 50% of their maximum particle size at the separation point or separation points, and an internal (3) being provided at each separation point, which internal is operated under at least partially flooded conditions, a continuous liquid phase being formed at least in partial regions of the internal (3), to which region the aerosols are bound.