This disclosure provides processes for forming acrylic acid and other α,β-unsaturated carboxylic acids and their salts, including catalytic processes, and catalyst systems for effecting the processes. For example, there is provided a catalyst system for producing an α,β-unsaturated carboxylic acid or a salt thereof, the catalyst system comprising: (a) a transition metal precursor compound comprising a Group 8-11 transition metal and at least one first ligand; (b) optionally, at least one second ligand; and (c) an anionic polyaromatic resin with associated metal cations. The catalyst system can further comprise (d) an olefin; (e) carbon dioxide (CO.sub.2); and (f) a diluent. Methods of regenerating the anionic polyaromatic resin with associated metal cations are described.

This disclosure provides processes for forming acrylic acid and other α,β-unsaturated carboxylic acids and their salts, including catalytic processes, and catalyst systems for effecting the processes. For example, there is provided a catalyst system for producing an α,β-unsaturated carboxylic acid or a salt thereof, the catalyst system comprising: (a) a transition metal precursor compound comprising a Group 8-11 transition metal and at least one first ligand; (b) optionally, at least one second ligand; and (c) an anionic polyaromatic resin with associated metal cations. The catalyst system can further comprise (d) an olefin; (e) carbon dioxide (CO.sub.2); and (f) a diluent. Methods of regenerating the anionic polyaromatic resin with associated metal cations are described.

Provided is a method for separating water-containing crystals, the method including: a step of generating water-containing crystals from a mixed liquid including water, acetic acid, and methacrylic acid; and a step of separating the crystals, in which the proportion by mass of methacrylic acid with respect to the total mass of water, acetic acid, and methacrylic acid in the mixed liquid is 0.09% by mass or more and less than 0.60% by mass.

Provided is a method for separating water-containing crystals, the method including: a step of generating water-containing crystals from a mixed liquid including water, acetic acid, and methacrylic acid; and a step of separating the crystals, in which the proportion by mass of methacrylic acid with respect to the total mass of water, acetic acid, and methacrylic acid in the mixed liquid is 0.09% by mass or more and less than 0.60% by mass.

An object of the present invention is to provide a catalyst capable of improving the selectivity of unsaturated aldehydes and unsaturated carboxylic acids, and a catalyst containing molybdenum, antimony, bismuth, and iron, wherein an atom ratio of the antimony to the molybdenum on a surface of the catalyst is greater than an atom ratio of the antimony to the molybdenum in the entire catalyst is provided.

An object of the present invention is to provide a catalyst capable of improving the selectivity of unsaturated aldehydes and unsaturated carboxylic acids, and a catalyst containing molybdenum, antimony, bismuth, and iron, wherein an atom ratio of the antimony to the molybdenum on a surface of the catalyst is greater than an atom ratio of the antimony to the molybdenum in the entire catalyst is provided.

The disclosure provides methods and apparatus for producing 3-hydroxypropionic acid or a salt thereof, for removing 3-hydroxypropionic acid from aqueous solution (e.g., aqueous broth), and for using it to make various chemicals.

The invention relates to a process for distillative removal of a unsaturated carboxylic anhydride of the general formula (I) R—C(O)—O—C—(O)—R in which R is an unsaturated organic radical having 2 to 12 carbon atoms, wherein said unsaturated carboxylic anhydride is discharged in gaseous form from a sidestream take-off and is condensed in an atomized liquid circulating stream of said unsaturated carboxylic anhydride.

The invention relates to a process for distillative removal of a unsaturated carboxylic anhydride of the general formula (I) R—C(O)—O—C—(O)—R in which R is an unsaturated organic radical having 2 to 12 carbon atoms, wherein said unsaturated carboxylic anhydride is discharged in gaseous form from a sidestream take-off and is condensed in an atomized liquid circulating stream of said unsaturated carboxylic anhydride.

This disclosure provides for catalyst systems and processes for forming an α,β-unsaturated carboxylic acid or a salt thereof. In an aspect, the catalyst system can comprise: a transition metal precursor comprising a Group 8-11 transition metal and at least one first ligand; optionally, at least one second ligand; an olefin; carbon dioxide (CO.sub.2); a diluent; and an oxoacid anion-substituted polyaromatic resin comprising a sulfonated polyaromatic resin, a phosphonated polyaromatic resin, a sulfinated polyaromatic resin, a thiosulfonated, or a thiosulfinated polyaromatic resin, and further comprising associated metal cations. Methods of regenerating the polyaromatic resin with associated metal cations are described.