| 摘要 |
An aqueous solution comprising acrylic acid and the conjugate base thereof in a total amount of at least 10% by weight, based on the weight of the aqueous solution, and propionic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, benzoic acid and the conjugate base thereof, maleic anhydride, maleic acid and the conjugate bases thereof, phthalic anhydride, phthalic acid and the conjugate bases thereof, acrolein, benzaldehyde, 2-furaldehyde, and at least 20 mol % of at least one alkali metal cation;
process for preparing this solution; andthe use of this solution for preparation of polymer by free-radical polymerization. |
| 主权项 |
1. A process for preparing an aqueous target product solution comprising acrylic acid and the conjugate base thereof, which comprises the following:
(1) at least one C3 precursor compound of acrylic acid is passed through a partial oxidation zone and partially oxidized therein to acrylic acid, wherein the at least one C3 precursor compound of acrylic acid is a constituent of a reaction gas input mixture comprising the at least one C3 precursor compound of acrylic acid, molecular oxygen and at least one inert diluent gas other than CO2 and water, and the at least one C3 precursor compound of acrylic acid is partially oxidized by a heterogeneously catalyzed gas phase partial oxidation in the partial oxidation zone over catalysts present in the solid state with the molecular oxygen to obtain a product gas mixture comprising CO2, water, the target product acrylic acid, and as secondary constituents formic acid, acetic acid, propionic acid, benzoic acid, acrolein, benzaldehyde, 2-furaldehyde, phthalic anhydride and/or phthalic acid, maleic anhydride and/or maleic acid, and at least one inert diluent gas other than CO2 and water, (2) the product gas mixture conducted out of the partial oxidation zone, optionally after its temperature has been reduced in a cooling zone by direct and/or indirect cooling, is conducted through an absorption zone I in which an absorbent I scrubs the secondary constituents benzoic acid, phthalic acid and/or the anhydride thereof and maleic acid and/or the anhydride thereof out of the product gas mixture by absorption to form an absorbate I, wherein the absorbent I is conducted in concurrent or in countercurrent to the product gas mixture, (3) the absorbate I is discharged from absorption zone I and the scrubbed product gas mixture conducted out of absorption zone I is conducted through a condensation zone I, in which an aqueous acrylic acid solution is condensed as condensate I out of the scrubbed product gas mixture by direct and/or indirect cooling thereof, with the proviso that there remains a CO2- and water-comprising residual gas mixture I which comprises the at least one inert diluent gas other than CO2 and water, the secondary constituents formic acid, acetic acid, propionic acid, acrolein, benzaldehyde and 2-furaldehyde and at least 10% of the amount of acrylic acid present in the product gas mixture, wherein the aqueous acrylic acid solution comprises the secondary constituents formic acid, acetic acid, propionic acid, acrolein, benzaldehyde and 2-furaldehyde in dissolved form, at least a portion of condensate I is conducted as absorbent I into the absorption zone I, and any remaining residual amount of condensate I is conducted out of condensation zone I as aqueous intermediate I, (4) the residual gas mixture I, conducted out of condensation zone I, is passed through an absorption zone II in which an aqueous alkali metal base scrubs acrylic acid, CO2, and the secondary constituents formic acid, acetic acid, propionic acid, acrolein, benzaldehyde and 2-furaldehyde, out of residual gas mixture I by absorption to form an aqueous alkali metal acrylate solution as absorbate II, leaving a residual gas mixture II which comprises the at least one inert diluent gas other than CO2 and water, a residual amount of acrylic acid and water, wherein the aqueous alkali metal base is conducted in concurrent or in countercurrent to the residual gas mixture I as absorbent II, residual gas mixture II is conducted out of absorption zone II, and absorbate II is withdrawn from absorption zone II as aqueous intermediate II, (5) carrying out the following (5A) or (5B) (5A) if no aqueous intermediate I is conducted out of condensation zone I, the acrolein, benzaldehyde and 2-furaldehyde secondary constituents present in the aqueous intermediate II are absorbed therefrom by extraction with an organic extractant, and remaining aqueous raffinate II is removed from an organic extract II formed as the aqueous target product solution comprising acrylic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, propionic acid and the conjugate base thereof, (5B) if aqueous intermediate I is conducted out of condensation zone I, the acrolein, (1) benzaldehyde and 2-furaldehyde secondary constituents present in the aqueous intermediate II are absorbed therefrom by extraction with an organic extractant, and remaining aqueous raffinate II is removed from an organic extract II formed, and the acrolein, benzaldehyde and 2-furaldehyde secondary constituents present in the aqueous intermediate I are absorbed therefrom by extraction with an organic extractant, and remaining aqueous raffinate I is removed from the organic extract I formed, wherein the aqueous raffinate II and the aqueous raffinate I are combined to give the aqueous target product solution comprising the acrylic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, propionic acid and the conjugate base thereof, optionally CO2 is outgassed from the aqueous target product solution, or (2) the aqueous intermediate II and the aqueous intermediate I are combined to give an aqueous intermediate III, and the acrolein, benzaldehyde and 2-furaldehyde secondary constituents present in the aqueous intermediate III are absorbed therefrom by extraction with an organic extractant, optionally CO2 is outgassed from the aqueous intermediate III beforehand, and the remaining aqueous raffinate III is removed from the organic extract III formed as the aqueous target product solution comprising acrylic acid and the conjugate base thereof, formic acid and the conjugate base thereof, acetic acid and the conjugate base thereof, propionic acid and the conjugate base thereof. |
