Abstract: The invention relates to an oxidation catalyst comprising at least one inorganic, oxidic or ceramic, shaped support body having a BET surface area of less than 0.5 m2/g, based on the support, which is at least partly coated with a catalytically active multielement oxide, the catalyst being precious metal-free and the shaped support body having the form of a saddle whose saddle surface is curved oppositely in the two principal directions, to a process for producing it, to its use in various catalytic gas phase oxidations, and to corresponding processes for catalytic gas phase oxidation.

Abstract: A heat exchanger (1) contains: a bundle of at least two heat exchanger tubes (3), a heat exchanger housing (5) surrounding the bundle of heat exchanger tubes (3), wherein a liquid heat-transfer medium (7) is passed around the bundle of heat exchanger tubes (3) in the heat exchanger housing (5), a heat exchanger cap (9) sealing the top of the heat exchanger housing (5), a heat exchanger bottom (11) sealing the bottom of the heat exchanger housing (5), a feed point (13) for the heat-transfer medium (7), an outlet (15) for the heat-transfer medium (7), an emergency relief port (17) disposed in proximity to the heat exchanger cap (9). The heat exchanger (1) contains a safety device (19) disposed in proximity to the heat exchanger bottom (11).

Abstract: A plant (1) for recovering acrylic acid, which includes: a absorption column (201); a dissociation column (205); a first line (101) connected to the dissociation column (205); a second line (102) connecting the absorption column (201) and the dissociation column (205); a third line (103) feeding a substream of the mother acid obtained in the crystallization into the dissociation column (205); a fourth line (104) connecting the crystallization apparatus and the absorption column (201); and a fifth line (105) connecting the dissociation column (205) and the absorption column (201).

Abstract: A process for recovering acrylic acid, including: a) division of a heated mother acid stream in direction of an absorption a condensation column and a dissociation column; b) feeding of a heated mother acid substream as runback to the dissociation column; c) feeding-in of at least one stripping gas stream to the dissociation column; d) feeding-in of a secondary component stream comprising oligomeric acrylic acid from the absorption column to the dissociation column; e) dissociation of part of oligomeric acrylic acid in the dissociation column to give monomeric acrylic acid; f) removal of secondary components comprised in the secondary component stream in the dissociation column; g) discharge of monomeric acrylic acid as gas mixture with introduced circulating stripping gas stream from the dissociation column; and h) feeding-in of the gas mixture to the absorption column.

Abstract: A hollow cylindrical shaped catalyst body for gas phase oxidation of an alkene to an ?,?-unsaturated aldehyde and/or an ?,?-unsaturated carboxylic acid comprises a compacted multimetal oxide having an external diameter ED, an internal diameter ID and a height H, wherein ED is in the range from 3.5 to 4.5 mm; the ratio q=ID/ED is in the range from 0.4 to 0.55; and the ratio p=H/ED is in the range from 0.5 to 1. The shaped catalyst body is mechanically stable and catalyzes the partial oxidation of an alkene to the products of value with high selectivity. It provides a sufficiently high catalyst mass density of the catalyst bed and good long-term stability with acceptable pressure drop.

Abstract: The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertically aligned column body (2) which forms a column cavity (3), having a sequence of vertically spaced-apart dual-flow mass transfer trays (8) which are mounted in the column cavity (3) and which have orifices for passage of liquid and gas in countercurrent, and having at least one gas entry orifice (5) disposed below the lowermost of the sequence of dual-flow mass transfer trays (8). It is a characteristic feature of the column of the invention that a gas distribution tray (9) which is disposed between the lowermost of the sequence of dual-flow mass transfer trays (8) and the gas entry orifice (5) has orifices (32) for vertical passage of gas which can be introduced into the column cavity (3) via the gas entry orifice (5), the orifices (32) being formed so as to bring about equal gas distribution over the column cross section.

Abstract: The present invention relates to a chimney tray (3) for a column (1) for thermal treatment of fluid mixtures, comprising a collecting tray (4) and at least two chimneys (5-1, 5-2) spaced apart horizontally in the collecting tray (4), where each chimney (5-1, 5-2) forms a vertically aligned chimney body (6-1, 6-2) which forms a passage orifice (7-1, 7-2) through the collecting tray (4), and has a cover unit (8-1, 8-2) arranged spaced apart from the chimney body (6-1, 6-2), and where the cover unit (8-1, 8-2) covers the respective passage orifices (7-1, 7-2) in the vertical direction.

Abstract: The present invention relates to an extraction column 1 having a vertically aligned column body 2 which is cylindrical at least in sections and forms a column cavity 3 having a horizontal maximum extent, with provision in the column body 2 of at least one first feed 4 for an extractant, at least one second feed 5 for the fluid to be extracted and at least one outlet 6 for the extract mixture and at least one outlet for the raffinate. In the inventive extraction column 1, a vertically aligned divider 7 arranged within the column cavity 3 subdivides the column cavity 3 into a plurality of vertically aligned and horizontally divided regions, the horizontal maximum extent of each region being less than the horizontal maximum extent of the column cavity 3. The invention further relates to a process for extracting a constituent from a fluid by means of such an extraction column 1.

Abstract: The present invention relates to a plant for performance of heterogeneously catalyzed gas phase reactions. The plant entails a reactor, at least one line leading into the reactor for introduction of reactants into the reactor, at least one first feed for providing at least one first reactant A, which leads into the line, at least one second feed for providing at least one second reactant B, which leads into the line, at least one third feed for providing a cycle gas G, which leads into the line, a temperature control unit which is disposed in the line upstream of the reactor and is for controlling the temperature of the first reactant A and/or second reactant B and/or cycle gas G prior to entry into the reactor and at least one outlet for products, by-products and/or unreacted reactants from the gas phase reaction.

Abstract: The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertical column body (2) which forms a column cavity (3), a plurality of trays (8) mounted in the column cavity (3) and spaced apart vertically from one another, at least one stub (11) disposed within the column body (2) and extending away from the column body (2), and a closable inspection orifice (9) formed in the stub (11). The characteristic feature of the column of the invention is that a spray device (20) disposed in the column body (2) can spray liquid (22) at least against the surface (15) of the stub (11) directed into the column cavity (3).

Abstract: The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertical column body (2) which forms a column cavity (3) and a vertical inner surface (16), a plurality of trays (8) mounted in the column cavity (3) and spaced apart vertically from one another, at least one stub (11) disposed within the column body (2) and extending away from the column body (2), and a closable inspection orifice (9) formed in the stub (11). The characteristic feature of the column of the invention is that in the case of a vertical cross section of the column (1) the surface (15) of the lower line of intersection of the stub (11) directed into the column cavity (3) or a tangent to the surface (15) of the lower line of intersection of the stub (11) at least in sections forms an angle within a range from 210° to 267° with the vertical inner surface (16) of the column body (2) which extends downward from the stub (11).

Abstract: The invention relates to a process for preparing butadiene from n-butenes having a start-up phase and an operating phase, wherein the process in the operating phase comprises the steps: A) provision of a feed gas stream a1 comprising n-butenes; B) introduction of the feed gas stream a1 comprising n-butenes, of an oxygen-comprising gas stream a2 and of an oxygen-comprising recycle gas stream d2 into at least one oxidative dehydrogenation zone and oxidative dehydrogenation of n-butenes to butadiene, giving a product gas stream b comprising butadiene, unreacted n-butenes, water vapor, oxygen, low-boiling hydrocarbons, high-boiling secondary components, possibly carbon oxides and possibly inert gases; C) cooling and compression of the product gas stream b and condensation of at least part of the high-boiling secondary components, giving at least one aqueous condensate stream c1 and a gas stream c2 comprising butadiene, n-butenes, water vapor, oxygen, low-boiling hydrocarbons, possibly carbon oxides and possibly

Abstract: The present invention describes a system (1) for recovering liquid or free-flowing chemicals in a chemical plant (3), comprising at least two plant sections (3a, 3b), for each plant section (3a, 3b) at least one connecting device (5a, 5b) arranged at the lowest point, at least one common collecting line (7) which runs beneath the connecting devices (5a, 5b) and connects them to one another, at least one collecting vessel (9) arranged at the same height as or higher than the at least two plant sections (3a, 3b) and above the collecting line (7), at least one pump (11) provided in the collecting line (7) between the connecting devices (5a, 5b) and the collecting vessel (9) for drawing off the at least one liquid or free-flowing chemical combined in the collecting line (7) and introducing it into the collecting vessel (9).

Abstract: The invention relates to a crossflow tray for a mass transfer column (27) in which a gas is conducted in countercurrent to a liquid, the crossflow tray (1) having passage orifices (3) for the gas and at least two downcomers (5), the downcomers (5) projecting beyond the top surface of the crossflow tray (1) and a collecting cup (13) being disposed beneath each downcomer (5). The downcomer (5) projects into the collecting cup (13), the minimum horizontal cross-sectional area of the collecting cup (13) is 1.2 to 4 times greater than the horizontal cross-sectional area of the downcomer (5) at the outlet, and the collecting cup (13) has a circumferential wall (15) having an overflow (19). The invention further relates to a mass transfer column comprising the crossflow trays and to a use of the mass transfer column.

Abstract: A process for replacing the stabilization of (meth)acrylic monomers, wherein phenothiazine is removed from phenothiazine-containing (meth)acrylic monomers by adsorption on activated carbon, and then a moderately active polymerization inhibitor is optionally added.

Abstract: The present invention relates to the process for recovering acrylic acid, comprising the steps a) division of a heated mother acid stream in direction of an absorption column (201) and a dissociation column (205), b) feeding of a heated mother acid substream as runback to the dissociation column (205), c) feeding-in of at least one stripping gas stream to the dissociation column (205), d) feeding-in of a secondary component stream comprising oligomeric acrylic acid from the condensation column (201) to the dissociation column (205), e) dissociation of part of oligomeric acrylic acid in the dissociation column (205) to give monomeric acrylic acid, f) removal of secondary components comprised in the secondary component stream in the dissociation column (205), g) discharge of monomeric acrylic acid as gas mixture with introduced circulating stripping gas stream from the dissociation column (205) and h) feeding-in of the gas mixture to the condensation column (201).

Abstract: The present invention relates to a process for treating secondary components obtained in acrolein and/or (meth)acrylic acid production, comprising the steps of: a) contacting at least one wastewater stream (201) comprising at least a portion of the water of reaction removed in a first stage of a saturation column (101) with at least one process offgas stream (203), b) introducing energy by means of a first heat transferer (103) provided in a first saturation circuit (301) into the first stage of the saturation column (101), c) partly vaporizing the wastewater stream (201) into the process offgas stream (203) and passing the combined gas stream (205) into a second stage of the saturation column (101), d) drawing off a concentrated wastewater stream (207) from the bottom (1011) of the first stage of the saturation column (101) and feeding it to the top (1023) of the second stage of the saturation column (101), e) introducing energy by means of a second heat transferer (105) provided in a second circuit (303)

Abstract: The present invention relates to a column (1) for thermal treatment of fluid mixtures, having a cylindrical, vertical column body (2) which forms a column cavity (3), a plurality of trays (8) mounted with vertical spacing in the column cavity (3), and a support construction (9) which supports at least one of the trays (8) in vertical direction. It is a characteristic feature of the inventive column (1) that the support construction (9) has a plurality of orifices (12) which allow horizontal mass transfer through the support construction (9). The invention further relates to a tray device for such a column and to a thermal separation process between at least one gas ascending within such a column (1) and at least one liquid descending within the column (1).

Abstract: The present invention relates to a column (1) for thermal treatment of a fluid, having a cylindrical, vertical column body (2) which forms a column cavity (3), and a mass transfer tray (4) which is disposed in the column cavity (3) and forms a collecting area (5). The inventive column (1) is characterized by a circulation device (9) having at least one drain orifice (10) formed in the column body (2) above the collecting area (5), a circulation line (11) in fluid connection with the drain orifice (10) and at least one recycling orifice (14; 14-1 to 14-3) which is in fluid connection with the circulation line (11) and is formed in the column body (2) above the collecting area (5). The invention also relates to a thermal separating process in which such a column (1) is used. In this separating process, a gas ascends within the column and a liquid descends within the column, said gas and/or liquid especially comprising (meth)acrylic monomers.

Abstract: What is described is a catalyst for preparation of an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde, comprising a shaped support body with an active composition applied thereto, wherein the active composition coverage q q = Q ( 100 - Q ) ? S m is at most 0.3 mg/mm2, where Q is the active composition content of the catalyst in % by weight and Sm is the specific geometric surface area of the shaped support body in mm2/mg. Also described are a process for preparing the catalyst and a process for preparing an ?,?-unsaturated carboxylic acid by gas phase oxidation of an ?,?-unsaturated aldehyde over a fixed catalyst bed comprising a bed of the catalyst. The catalyst, with constantly high conversion of acrolein, reduces overoxidation to COx and increases the selectivity of acrylic acid formation.