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.

The present disclosure includes a column (1) having a cylindrical, vertical column body (2) forming a column cavity (3), and a mass transfer tray (4) disposed in the column cavity (3) and forming a collecting area (5). The 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). Also disclosed herein is a thermal separating process in which a gas ascends within a column (1) of the present disclosure, and a liquid descends within the column (1), said gas and/or liquid containing (meth)acrylic monomers.

Aspidin BB derivatives, compositions containing them, and methods of making and using them.

A process for production of acrylic acid includes preparing a product gas mixture by a catalytic gas-phase oxidation of a C.sub.3 precursor; cooling and contacting the cooled product gas mixture in an absorption column having at least two cooling loops in countercurrent with an absorbent to obtain an absorbate A, containing the absorbent and absorbed acrylic acid; condensing a high boiler fraction of the product gas mixture in a first cooling loop; condensing a low boiler fraction of the product gas mixture in a second cooling loop; maintaining a temperature of the absorbate A in the second cooling loop at a value of at least 56 C.; removing an acid water stream comprising glyoxal from the absorption column at a side take-off located above the second cooling loop; and removing a stream F of absorbate A from the absorption column at a side take-off, located at a height of the absorption column between the first cooling loop and the second cooling loop.

A process for preparing acrylic acid from methanol and acetic acid, comprising (i) contacting a gaseous stream S0 comprising methanol, oxygen and inert gas with an oxidation catalyst to obtain a gaseous stream S1 comprising formaldehyde and inert gas; (ii) removing at least a portion of the inert gas present in S1 from at least a portion of the formaldehyde present in S1 by absorbing this formaldehyde in an absorbent to obtain a gaseous stream S2 comprising the portion of the inert gas removed, and to obtain a stream S3 comprising absorbent and absorbate comprising formaldehyde; (iii) optionally removing a portion or the entirety of the absorbent present in stream S3, such that a stream S3a remains from stream S3, and producing a stream S4 from at least stream S3 or stream S3a and a stream S5 comprising acetic acid; and (iv) contacting stream S4 in gaseous form with an aldol condensation catalyst to obtain a gaseous stream S6 comprising acrylic acid.

The invention is related to a process for production of acrylic acid comprising the following steps: a) preparation of a product gas mixture by a catalytic gas-phase oxidation of at least one C.sub.3 precursor compound to acrylic acid, wherein acrylic acid is formed as a main product of the catalytic gas-phase oxidation and glyoxal is formed as a by-product and the product gas mixture comprises acrylic acid and glyoxal, b) cooling of the product gas mixture, c) contacting the product gas mixture in countercourrent with an absorbent, wherein an absorbate A, comprising the absorbent and absorbed acrylic acid, is formed, d) introducing a feed stream F (2) comprising at least part of the absorbate A into a rectification column comprising a rectifying section and a stripping section, e) enriching the absorbent in the stripping section and enriching acrylic acid in the rectifying section, f) withdrawing a stream C of crude acrylic acid comprising at least 90% by weight of acrylic acid out of the rectifying section as a side stream,
wherein step c) is carried out in an absorption column (12) comprising at least two cooling loops, a first cooling loop (14), wherein a high boiler fraction of the product gas mixture is condensed and a second cooling loop (16), wherein a low boiler fraction of the product gas mixture is condensed,
wherein a portion of the absorbate A, which comprises the feed stream F (2), is removed from the absorption column (12) at a side take-off (20), the side take-off (20) being located at the first cooling loop (14) or at a height of the absorption column (12) between the first cooling loop (14) and the second cooling loop (16)
and wherein a temperature Tc of the absorbate A in the second cooling loop is at least 56 C.

Provided is a method for producing fluorenone comprising an oxidation step of oxidizing fluorene in the presence of an aliphatic carboxylic acid having 2 to 3 carbon atoms, a metal catalyst, a bromine compound, and oxygen, and a phosphoric acid treatment step of bringing an oxidation reaction mixture into contact with phosphoric acid in the order indicated.

A process for producing an aldehyde is disclosed. The process comprises: hydroformylating an olefin to form the aldehyde using a hydroformylation catalyst; recovering an effluent stream comprising the aldehyde, hydrogen and the hydroformylation catalyst; passing the effluent stream to a stripper; contacting the effluent stream with a strip gas in the stripper to produce a stripped effluent stream having a lower hydrogen concentration than the effluent stream; and recovering the stripped effluent stream.

A method for preparing an aldehyde including: reacting reactants in a reactor to obtain a reaction product; supplying the reaction product to a first flash drum, performing gas-liquid separation, and supplying a liquid separated product to a vaporization part including a vaporizer; vaporizing the liquid from the vaporization part separate-into a vapor stream and a liquid stream; supplying the vapor stream to a second flash drum to separate an upper discharge stream and a lower discharge stream from the second flash drum; and supplying the upper discharge stream from the second flash drum to one or more flash drums, and supplying the lower discharge stream from the second flash drum to a distillation tower and performing distillation to obtain the aldehyde from a lower discharge stream from the distillation tower, wherein a ratio of an operating temperature of the vaporizer to a reaction temperature of the reactor is controlled.