Abstract:
The invention relates to a method for the heterogeneously catalysed partial gas phase oxidation of propylene to form acrylic acid. According to said method, the reaction starting mixture contains cyclopropane as an impurity, and the acrylic acid is separated off by means of separation by crystallisation after being transformed from the product gas mixture into the condensed phase.
Abstract:
The invention relates to a method for the heterogeneously catalysed partial gas phase oxidation of propene to form acrylic acid. According to said method, the initial mixture of reaction gas containing propene is oxidised, in a first reaction step, on a fixed-bed catalyst bed (1) consisting of a plurality of fixed-bed catalyst bed zones and arranged in two successive temperature zones A and B. The acrolein-containing product gas mixture of the first reaction step is then oxidised, in a second reaction step, on a fixed-bed catalyst bed (2) consisting of a plurality of fixed-bed catalyst bed zones and arranged in two successive temperature zones C and D. The transition from one temperature zone to another temperature zone does not spatially coincide with a transition from a fixed-bed catalyst bed zone to another fixed-bed catalyst bed zone within a reaction step.
Abstract:
A catalyst comprising (i) a support, (ii) metal particles and (iii) a shell which is arranged between the metal particles, wherein the shell (iii) comprises silicon oxide.
Abstract:
A catalyst is provided, preferably for the use in selective catalytic reduction (SCR). Said catalyst comprises one or more zeolites of the MFI structure type, and one or more zeolites of the CHA structure type, wherein at least part of the one or more zeolites of the MFI structure type contains iron (Fe), and wherein at least part of the one or more zeolites of the CHA structure type contains copper (Cu). Furthermore, provided are an exhaust gas treatment system comprising said catalyst as well as a process for the treatment of a gas stream comprising NOX using said catalyst as well.
Abstract:
Disclosed is a method for producing catalytically active multielement oxide materials containing at least one of the elements Nb and W as well as elements Mo, V, and Cu. According to the inventive method, an intimate dry mixture containing ammonium ions is produced and is thermally treated at a raised temperature in an atmosphere that is low in molecular oxygen. A partial quantity of the ammonium ions contained in the intimate dry mixture is decomposed so as to release ammonia while the oxygen concentration of the thermal treatment atmosphere is increased in the course of the thermal treatment.