Abstract: The invention relates to a method for producing butadiene from n-butenes having the steps: A) providing a feed gas stream a comprising n-butenes; B) feeding the feed gas stream a comprising the n-butenes and an oxygen-comprising gas into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, wherein a product gas stream b comprising butadiene, unreacted n-butenes, steam, oxygen, low-boiling hydrocarbons, high-boiling minor components, possibly carbon oxides and possibly inert gases is obtained; Ca) cooling the product gas stream b by contacting it with a refrigerant and condensing at least a part of the high-boiling minor components; Cb) compressing the remaining product gas stream b in at least one compression stage, wherein at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, steam, oxygen, low-boiling hydrocarbons, possibly carbon oxides and possibly inert gases are obtained; Da) separating off non-condensable and low-b

Abstract: The invention relates to a method for producing butadiene from n-butenes having the steps: A) providing a feed gas stream a comprising n-butenes; B) feeding the feed gas stream a comprising the n-butenes and an oxygen-comprising gas into at least one oxidative dehydrogenation zone and oxidatively dehydrogenating n-butenes to butadiene, wherein a product gas stream b comprising butadiene, unreacted n-butenes, steam, oxygen, low-boiling hydrocarbons, high-boiling minor components, possibly carbon oxides and possibly inert gases is obtained; Ca) cooling the product gas stream b by contacting it with a refrigerant and condensing at least a part of the high-boiling minor components; Cb) compressing the remaining product gas stream b in at least one compression stage, wherein at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, steam, oxygen, low-boiling hydrocarbons, possibly carbon oxides and possibly inert gases are obtained; Da) separating off non-condensable and low-b

Abstract: Iron- and manganese-comprising heterogeneous catalyst and process for producing it, which comprises the following steps: I. thermal decomposition of gaseous iron pentacarbonyl to give carbonyl iron powder having spherical primary particles, II. treatment of carbonyl iron powder obtained in step I with hydrogen, resulting in the metallic spherical primary particles at least partly agglomerating, III. surface oxidation of the iron particles from step II (i.e. agglomerates=secondary particles, and also any primary particles still present) to form iron oxide, IV. contacting of the particles from step III with an aqueous solution of a manganese compound, V. drying in the presence of oxygen and subsequent calcination in the absence of oxygen, resulting firstly in oxygen-comprising manganese compounds on the particles and finally reaction of these with the iron oxide to form a mixed oxide of the formula MnxFe3-xO4, where 0<x?2.

Abstract: Iron- and copper-comprising heterogeneous catalyst and process for producing it, which comprises the following steps: I. thermal decomposition of gaseous iron pentacarbonyl to give carbonyl iron powder having spherical primary particles, II. treatment of carbonyl iron powder obtained in step I with hydrogen, resulting in the metallic spherical primary particles at least partly agglomerating, III. surface oxidation of the iron particles from step II (agglomerates=secondary particles, and also any primary particles still present) to form iron oxide, IV. contacting of the particles from step III with an aqueous solution of a copper compound, V. drying in the presence of oxygen and subsequent calcination in the absence of oxygen, resulting firstly in oxygen-comprising copper compounds on the particles and finally reaction of these with the iron oxide to form a mixed oxide of the formula CuxFe3-xO4, where 0<x?1.