Abstract:
A process for the preparation of mononitroaromatics and dinitroaromatics, in which a hydrate melt of at least one metal nitrate M(NO3)3 is used as a nitrating medium, it being possible for M to be the metals Fe, Cr, Y, La, Ce, Al, Bi and In, and the metal nitrate having a water content of from 4 to 9 mol of water per M(NO3)3, leads to simplifications of the process and improved yields.
Abstract:
A chemical process for preparing at least one aromatic isocyanate, said process comprising n chemical sub-processes sp(i), wherein a sub-process sp(i) is carried out in a chemical processing sub-unit U(i), i=1 . . . n, n≥1, wherein during a regular operating mode of a sub-unit U(i), the sub-process sp(i) being carried out in said sub-unit U(i) comprises feeding an educt composition E(i) comprising at least one aromatic compound ZjE(i), j≥(i), into said sub-unit U(i), processing said composition E(i) in said sub-unit U(i) and obtaining a product composition P(i) comprising at least one aromatic compound Zkp(i), k≥1, wherein the chemical process comprises starting up said sub-process sp(i) in said sub-unit U(i), wherein said starting-up comprises processing a chemical start-up composition S(i) in said sub-unit U(i), wherein said S(i) #E(i) and wherein said S(i) comprises at least one of the aromatic compounds Zkp(i).
Abstract:
A chemical production assembly for producing an isocyanate. comprising n serially arranged units U (i), i=1 . . . n, n≥2. wherein a unit U(i) is for preparing a chemical product cp(i) at a preparation rate PR(i) by using, as starting material. a chemical product cp(i+1) preprared in the unit U(i+1) ar—ranged upstream of said unit U(i), wherein said unit U(i) comprises an inlet means for receiving said chemical product cp(i+1) at an input rate IR(i). said unit U(i) being characterized by a nominal preparation rate PRN(i) and a nominal input rate IRN(i); and a unit U(i+1), i=1 . . . n-1, is for preparing the chemical product cp(i+1) and for supplying said chemical product cp(i+1) to the inlet means of the unit U(i) arranged downstream of said unit U(i+1) at a supply rate SR(i+1) with SR(i+1)=IR(i).
Abstract:
The invention relates to a process for concentrating diluted sulfuric acid (10) which may comprise at least one nitroaromatic compound and/or nitric acid as impurities, comprising: (a) feeding the diluted sulfuric acid (10) into a first stage (1) in which low boilers are removed by evaporation and/or stripping to obtain a first concentrated sulfuric acid (12); (b) optionally feeding the first concentrated sulfuric acid (12) into a second evaporation stage (2) to obtain a second concentrated sulfuric acid (14); (c) feeding the second concentrated sulfuric (14) acid into a third evaporation stage (3) if step (b) is carried out, or feeding the first concentrated sulfuric acid (12) into the third evaporation stage (3) if step (b) is not carried out, to obtain concentrated sulfuric acid (16) as product, wherein an oxidizing agent (17) and/or a precursor of an oxidizing agent is fed into the third evaporation stage (3).
Abstract:
A feed supply unit comprising (a) a feed dosage unit for supplying a viscosity unstable liquid feed to a reactor, (b) a flushing unit for flushing at least a part of the feed dosage unit according to (a) with a flushing medium, and (c) a signal transmission means for transmitting a signal from a monitoring means to a control means.
Abstract:
The invention relates to a process for preparing aromatic amines by hydrogenation of corresponding nitroaromatics by means of hydrogen, and also an apparatus suitable for this purpose. In particular, the invention relates to a process for preparing toluenediamine (TDA) by hydrogenation of dinitrotoluene (DNT).