Abstract:
The invention relates to a catalyst for producing an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde, comprising a moulded body support having an active material applied thereto, characterised in that the active material covering q is a maximum 0.3 mg/mm 2 , Q being the active material part of the catalyst in wt.-% and S m being the specific geometric surface of the moulded body support in mm 2 /mg. The invention also relates to a method for producing said catalyst and to a method for producing an α,β-unsaturated carboxylic acid by gas phase oxidation of an α,β-unsaturated aldehyde on a fixed bed catalyst which contains the bulk material of the catalyst. Due to said catalyst, the over-oxidation into CO x is reduced and the selectivity of the formation of acrylic acid is increased, whilst maintaining a continuous high yield in acroleine.
Abstract:
A thermal separating method between a gas rising in a separation column and a liquid, containing (meth)acrylic monomers, descending in the separation column, wherein the separation column contains a sequence of cross-current material exchange trays, the cross-current material exchange trays of which have passage openings for the rising gas both upstream and downstream, in the direction of the cross current, of an outlet shaft for the descending liquid, as well as such cross-current material exchange trays, and a sequence of cross-current material exchange trays contained in a separation column.
Abstract:
The invention relates to a method for the restabilization of (meth)acrylic monomers, whereby phenothiazine is removed from phenothiazine-containing (meth)acrylic monomers by adsorption on activated carbon and optionally subsequent addition of a moderately effective polymerization inhibitor.
Abstract:
The invention relates to a hydraulically-sealed cross-current material exchange tray, separating columns comprising a hydraulically-sealed cross-current material exchange tray and the use of said columns for thermal separation processes.
Abstract:
The invention relates to a method for producing acrylic acid by means of two-stage heterogeneously catalyzed partial gas phase oxidation of propylene. According to said method, previously dehydrogenated propane is used as a propylene source while the first partial oxidation stage is operated so as to limit propylene reaction. Furthermore, unreacted propane and propylene contained in the product gas mixture of the second partial oxidation stage are largely redirected into the propane dehydrogenation process taking place upstream.
Abstract:
The invention relates to a method for starting a heterogeneously catalyzed partial gas phase oxidation of acrolein into acrylic acid or of methacrolein into methacrylic acid at a fixed catalyst bed that is located in a shell-and-tube reactor cooled with a heat exchanger means, wherein the temperature of the heat exchanger means is ≥ 290°C, and wherein the temperature of the reactor bottom surface facing the reactor gas inlet mixture and the temperature of the reaction gas inlet mixture are ≤ 285°C.
Abstract:
The invention relates to a method for transporting a liquid monomer phase, which has been removed from a storage container, in a tanker lorry or tanker ship, said phase containing up to ≥ 90 % by weight methacryl monomers. According to said method, the liquid monomer phase is subjected to an isolation operation for isolating polymer contained in dissolved form in the liquid monomer phase from the monomer as said phase is removed from the storage container and transferred to the tank of a tanker lorry or a tanker ship.
Abstract:
The invention relates to a method for operating a continuous heterogeneously catalysed gas-phase partial oxidation of at least one organic compound. Said method uses compressed air as the oxygen source, said air being filtered prior to compression.
Abstract:
A process for heterogeneously catalysed gas phase partial oxidation of an organic starting compound over a fixed catalyst bed freshly installed in a reaction chamber, in which the reduction of the quality of the fixed catalyst bed is restored with increasing operating time by replacing part of the fixed catalyst bed with a replacement partial fixed catalyst bed whose volume-specific activity is lower than the volume-specific activity of the replaced partial fixed catalyst bed in its freshly installed state.