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.

The present disclosure relates generally to solid/liquid separation processes. One aspect of the disclosure is a process including filtering a solid/liquid mixture comprising a solid crude aromatic carboxylic acid, a monocarboxylic acid solvent, and minor amounts of an oxidation catalyst in a feed zone of a rotary filter (e.g., a rotary pressure filter), the feed zone having at least two filter zones to form a first feed filtrate comprising monocarboxylic acid solvent and solids; and a second feed filtrate separate from the first feed filtrate, the second feed filtrate comprising monocarboxylic acid solvent and solids, the second feed filtrate being lower in solids than the first feed filtrate; and transferring at least a portion of the first feed filtrate to the reactor zone as recycle.

The present disclosure relates generally to solid/liquid separation processes. One aspect of the disclosure is a process including filtering a solid/liquid mixture comprising a solid crude aromatic carboxylic acid, a monocarboxylic acid solvent, and minor amounts of an oxidation catalyst in a feed zone of a rotary filter (e.g., a rotary pressure filter), the feed zone having at least two filter zones to form a first feed filtrate comprising monocarboxylic acid solvent and solids; and a second feed filtrate separate from the first feed filtrate, the second feed filtrate comprising monocarboxylic acid solvent and solids, the second feed filtrate being lower in solids than the first feed filtrate; and transferring at least a portion of the first feed filtrate to the reactor zone as recycle.

The present disclosure relates generally to solid/liquid separation processes. One aspect of the disclosure is a process including filtering a solid/liquid mixture comprising a solid crude aromatic carboxylic acid, a monocarboxylic acid solvent, and minor amounts of an oxidation catalyst in a feed zone of a rotary filter (e.g., a rotary pressure filter), the feed zone having at least two filter zones to form a first feed filtrate comprising monocarboxylic acid solvent and solids; and a second feed filtrate separate from the first feed filtrate, the second feed filtrate comprising monocarboxylic acid solvent and solids, the second feed filtrate being lower in solids than the first feed filtrate; and transferring at least a portion of the first feed filtrate to the reactor zone as recycle.

A method for producing 2,2′-bis(carboxymethoxy)-1,1′-binaphthyl includes a separation step of separating a metal salt of 2,2′-bis(carboxymethoxy)-1,1′-binaphthyl from a reaction mixture by solid-liquid separation. In the method, a 2,2′-bis(alkoxycarbonylmethoxy)-1,1′-binaphthyl is used as a starting material.

A method for producing 2,2′-bis(carboxymethoxy)-1,1′-binaphthyl includes a separation step of separating a metal salt of 2,2′-bis(carboxymethoxy)-1,1′-binaphthyl from a reaction mixture by solid-liquid separation. In the method, a 2,2′-bis(alkoxycarbonylmethoxy)-1,1′-binaphthyl is used as a starting material.

A process for removing lactic acid from an aqueous lactic acid-containing magnesium chloride solution, the weight ratio of magnesium chloride to lactic acid in the aqueous lactic acid-containing magnesium chloride solution being at least 1:1, the process including the steps of subjecting the aqueous lactic acid-containing magnesium chloride solution to an evaporation step, resulting in the formation of a slurry of MgC12.MgL2.4H2O in an aqueous magnesium chloride solution, then subjecting the slurry to a solid-liquid separation step, to separate the solid MgC12.MgL2.4H2O from the aqueous magnesium chloride solution, resulting in the removal of lactic acid from the aqueous lactic acid-containing magnesium chloride solution in the form of MgC12.MgL2.4H2O. The process makes it possible to efficiently remove lactic acid from aqueous lactic acid-containing magnesium chloride solutions, resulting in magnesium chloride solutions with a low lactic acid content which can be further processed as desired.

A process for removing lactic acid from an aqueous lactic acid-containing magnesium chloride solution, the weight ratio of magnesium chloride to lactic acid in the aqueous lactic acid-containing magnesium chloride solution being at least 1:1, the process including the steps of subjecting the aqueous lactic acid-containing magnesium chloride solution to an evaporation step, resulting in the formation of a slurry of MgC12.MgL2.4H2O in an aqueous magnesium chloride solution, then subjecting the slurry to a solid-liquid separation step, to separate the solid MgC12.MgL2.4H2O from the aqueous magnesium chloride solution, resulting in the removal of lactic acid from the aqueous lactic acid-containing magnesium chloride solution in the form of MgC12.MgL2.4H2O. The process makes it possible to efficiently remove lactic acid from aqueous lactic acid-containing magnesium chloride solutions, resulting in magnesium chloride solutions with a low lactic acid content which can be further processed as desired.

Provided is a method for producing a composition containing gallic acid, the composition having a low content rate of protocatechuic acid using a microbial culture solution. A method for producing a composition containing gallic acid, the method comprising a step (A) of performing cooling crystallization using an aqueous solution (a) containing gallic acid and protocatechuic acid at 0.9° C./min or less.