摘要:
A catalyst suitable for the gas-phase oxidation of organic compounds to α,β-unsaturated aldehydes and/or carboxylic acids and having an active phase comprising a multimetal oxide material is prepared by a process in which a particulate catalyst precursor which contains oxides and/or compounds of the elements other than oxygen which constitute the multimetal oxide material, which compounds can be converted into oxides, is prepared and said catalyst precursor is converted by calcination into a catalytically active form, wherein a stream of the particulate catalyst precursor is passed at substantially constant speed through at least one calcination zone at constant temperature for calcination.
摘要:
A process for preparing a multielement oxide composition comprising the element iron in oxidic form, in which the source of the elemental constituent of iron used is an aqueous iron nitrate solution whose preparation comprises the melting of a solid hydrate of iron nitrate.
摘要:
An eggshell catalyst consisting of a hollow cylindrical support body of length 2 to 10 mm, external diameter 4 to 10 mm and wall thickness 1 to 4 mm, and an eggshell, applied to the outer surface of the support body, of catalytically active oxide material of the general formula I, Mo12V2 to 4W0 to 3Cu0.8 to 1.5X10 to 4X20 to 40On (I) in which the variables are each defined as follows: X1=one or more elements of the alkali metals and alkaline earth metals; X2=one or more elements from the group of Si, Al, Ti and Zr; and n=the stoichiometric coefficient of the element oxygen, which is determined by the stoichiometric coefficients of the elements other than oxygen and the charges thereof in I.
摘要:
A process for continuously removing a target product X in the form of fine crystals from a liquid phase P comprising the target product X and constituents other than the target product X by cooling suspension crystallization in the secondary chamber, into which the liquid phase P flows continuously, of an indirect heat exchanger with simultaneous continuous flow of a coolant through the primary chamber of the indirect heat exchanger and continuous withdrawal of a crystal suspension S having a degree of crystallization Y from the secondary chamber, in which the degree of crystallization Y is adjusted on the basis of a heat balance conducted continuously with the aid of a process computer.
摘要:
A process for starting up a separating process for purifying removal of acrylic acid crystals from a suspension S of crystals thereof in mother liquor with a hydraulic wash column which has a crystal melt circuit including crystal melt space, and a process space and a distributor space which are separated by an end with passages connecting the two spaces, in which the crystal bed is formed for the first time by first filling the crystal melt circuit and, at least partly, the process space with an acrylic acid-comprising startup liquid whose acrylic acid crystal formation temperature is less than or equal to the temperature of the suspension S increased by 15° C., and then continuing the filling of the wash column with the suspension S and optionally with control liquor until the difference between the pressure in the crystal melt space and the pressure in the distributor space falls suddenly, the arithmetic mean of the total waste liquor flow flowing through the filters of the filter tubes of the wash column until this time, based on the area of all filters, being not more than 80 m3/(m2·h).
摘要:
A process for producing geometric shaped catalyst bodies K whose active material is a multielement oxide of stoichiometry [BiaZ1bOx]p[BicMo12FedZ2eZ3fZ4gZ5hZ6iOy]1, in which a finely divided oxide BiaZ1bOx and, formed from element sources, a finely divided mixture of stoichiometry BicMo12FedZ2eZ3fZ4gZ5hZ6i are mixed in a ratio of p:1, this mixture is used to form shaped bodies and these are treated thermally, where 0
摘要:
A process for the heterogeneously catalyzed gas-phase partial oxidation of an organic compound over a fixed catalyst bed present in a fixed-bed reactor having a plurality of catalyst tubes, in which the reduction of the quality of the catalyst load with increasing duration of operation is restored by a partial catalyst change, is described.
摘要:
A process for preparing a multimetal oxide material which contains the elements Mo, V and Te and/or Sb and at least one of the elements Nb, Ti, W, Ta and Ce and if desired promoters and has a specific X-ray diffraction pattern, in which process the last process step comprises washing with acidic liquids. In addition, a multimetal oxide material obtainable in such a way is used as a catalyst for heterogeneously catalyzed gas-phase partial oxidations and/or ammoxidation of hydrocarbons.
摘要:
In a process for the two-stage catalytic gas-phase oxidation of propene to acrylic acid, the reaction gas starting mixture is passed, in a tube-bundle reactor, with a propene loading of ≧160 l (S.T.P.) of propene/l·h, first over a fixed catalyst bed 1 present in two successive temperature zones A, B and then over a fixed catalyst bed 2 which is housed either in one further temperature zone C or in two further temperature zones D, E, the temperature of the zone A being kept at a lower temperature than the zone B and the temperature of the zone D at a lower temperature than the zone E.
摘要:
In a process for the preparation of acrolein by gas-phase partial oxidation under heterogeneous catalysis, a reaction gas starting mixture which contains propene and molecular oxygen in a molar C3H6:O2 ratio of >1 is reacted in reaction zones connected in series, at elevated temperatures, over solid-state catalysts, further molecular oxygen being added to the reaction gas mixture in the course of the partial oxidation.