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).

Abstract: A regenerable deep bed filter element and method for making it, the element being provided as a closed system, in the case of which a deep bed filter (21), disposed inside at least one hollow-cylindrical chamber (17), is formed by a bulk material filling of regenerable, filtration-active substances of a particulate and/or fibrous structure. The hollow-cylindrical chamber accommodates radial flow by means of porous inner and outer peripheral walls (18, 19). The deep bed filter can be either washed, or regenerated by flushing back with water, steam or chemical cleansing agents, during which the filtration-active substances remain inside the chamber (17).

Abstract: A filter cartridge with a filter element inserted in a receiving space formed by a central cylindrical flow pipe 32 and a peripheral wall 34 is in terms of its possibilities of use and possibilities of adaptation to filtration problems substantially improved in that the filter element consists of fleece-like filter material and in that in its radial direction it comprises mutually enclosing zones of different filtering properties. For practical purposes, these zones can follow one another without any transition or they may be constructed with filtering properties which are varied in stepwise fashion. The filter element can be formed by the combination of a pleated filter fleece with a rolled-up filter fleece, the pleated part of the filter element being optionally on the inside or the outside.

Abstract: A flexible fleece-like filter material is provided wherein in a matrix-like basic framework consisting of synthetic or natural fibres, ultra-finely fibrillated fibres and/or inert porous particles are incorporated as a filter medium, the filter medium forming, anchored in the matrix, chain structures provided with a cationic or anionic charge or possibly charged with other substances which influence the filtering properties or with immobilised cells and/or catalysts. A fleece is formed with a thickness of between 0.5 mm and 5 mm and preferably up to 2 mm, which is flexible and which can even be pleated. This filter material can be produced by a simple method without harming the environment.

Abstract: A regenerable deep bed filter element provided as a closed system, in the case of which a deep bed filter (21), disposed inside at least one hollow-cylindrical chamber (17), if formed by a bulk material filling of regenerable, filtration-active substances of a particulate and/or fibrous structure. The hollow-cylindrical chamber can be flowed through radially by means of porous inner and outer peripheral walls (18, 19). The deep bed filter can be regenerated by flushing back with water, steam or chemical cleansing agents, during which the filtration-active substances remain inside the chamber (17).

Abstract: A filter cartridge with a filter element inserted in a receiving space formed by a central cylindrical flow pipe 32 and a peripheral wall 34 is in terms of its possibilities of use and possibilities of adaptation to filtration problems substantially improved in that the filter element consists of fleece-like filter material and in that in its radial direction it comprises mutually enclosing zones of different filtering properties. For practical purposes, these zones can follow one another without any transition or they may be constructed with filtering properties which are varied in stepwise fashion. The filter element can be formed by the combination of a pleated filter fleece with a rolled-up filter fleece, the pleated part of the filter element being optionally on the inside or the outside.