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.

Disclosed is a process for producing terephthalic acid. The process includes contacting p-xylene with a gaseous stream containing oxygen (O.sub.2) in presence of a homogeneous catalyst solution, at a reaction temperature of 180° C. to 195° C. to oxidize at least a portion of the p-xylene and form a product stream containing terephthalic acid, said homogeneous catalyst solution contains 350 ppm to 450 ppm cobalt (Co), 170 ppm to 270 ppm manganese (Mn), and 410 ppm to 510 ppm bromine (Br), wherein a Br/(Co+Mn) wt. % ratio is 0.5:1 to 1:1, and a Co to Mn wt. % ratio is 1.5:1 to 2:1.

Disclosed is a process for producing terephthalic acid. The process includes contacting p-xylene with a gaseous stream containing oxygen (O.sub.2) in presence of a homogeneous catalyst solution, at a reaction temperature of 180° C. to 195° C. to oxidize at least a portion of the p-xylene and form a product stream containing terephthalic acid, said homogeneous catalyst solution contains 350 ppm to 450 ppm cobalt (Co), 170 ppm to 270 ppm manganese (Mn), and 410 ppm to 510 ppm bromine (Br), wherein a Br/(Co+Mn) wt. % ratio is 0.5:1 to 1:1, and a Co to Mn wt. % ratio is 1.5:1 to 2:1.

Disclosed is a process for producing terephthalic acid. The process includes contacting p-xylene with a gaseous stream containing oxygen (O.sub.2) in presence of a homogeneous catalyst solution, at a reaction temperature of 180° C. to 195° C. to oxidize at least a portion of the p-xylene and form a product stream containing terephthalic acid, said homogeneous catalyst solution contains 350 ppm to 450 ppm cobalt (Co), 170 ppm to 270 ppm manganese (Mn), and 410 ppm to 510 ppm bromine (Br), wherein a Br/(Co+Mn) wt. % ratio is 0.5:1 to 1:1, and a Co to Mn wt. % ratio is 1.5:1 to 2:1.

A method of production of malic acid includes treating a first intermediate product to form a second intermediate product. The treating includes substantially removing impurities from the first intermediate product to obtain a treated intermediate product by gas stripping the crude maleic anhydride, or subjecting a mixture of one or more of the crude maleic acid, the crude fumaric acid, and the vent gas scrubber solution obtained from a phthalic anhydride production process or a maleic anhydride production process to crystallization, passing an aqueous solution of the treated intermediate product through a carbon column to substantially remove retained impurities to form the second intermediate product, obtaining a feed that includes the second intermediate product, and causing the feed to undergo hydration reaction in a tubular reactor or a continuous stirred tank reactor to produce malic acid.

A method of production of malic acid includes treating a first intermediate product to form a second intermediate product. The treating includes substantially removing impurities from the first intermediate product to obtain a treated intermediate product by gas stripping the crude maleic anhydride, or subjecting a mixture of one or more of the crude maleic acid, the crude fumaric acid, and the vent gas scrubber solution obtained from a phthalic anhydride production process or a maleic anhydride production process to crystallization, passing an aqueous solution of the treated intermediate product through a carbon column to substantially remove retained impurities to form the second intermediate product, obtaining a feed that includes the second intermediate product, and causing the feed to undergo hydration reaction in a tubular reactor or a continuous stirred tank reactor to produce malic acid.

A built-in micro interfacial enhanced reaction system and process for PTA production with PX are provided. The system includes a reactor and a micro interfacial unit disposed inside reactor. The reactor includes a shell, an inner cylinder concentrically disposed inside shell, and a circulating heat exchange device partially disposed outside shell, inner cylinder having a bottom end connected to inner bottom surface of the shell in closed manner and an open top end, a region between shell and inner cylinder being first reaction zone, inner cylinder containing second reaction zone and third reaction zone from top to bottom, circulating heat exchange device being connected to inner cylinder and micro interfacial unit respectively. The invention can solve problems of large waste of reaction solvent acetic acid under high temperature and high pressure and being unable to take out the product TA in time during existing process of PTA production with PX.

A built-in micro interfacial enhanced reaction system and process for PTA production with PX are provided. The system includes a reactor and a micro interfacial unit disposed inside reactor. The reactor includes a shell, an inner cylinder concentrically disposed inside shell, and a circulating heat exchange device partially disposed outside shell, inner cylinder having a bottom end connected to inner bottom surface of the shell in closed manner and an open top end, a region between shell and inner cylinder being first reaction zone, inner cylinder containing second reaction zone and third reaction zone from top to bottom, circulating heat exchange device being connected to inner cylinder and micro interfacial unit respectively. The invention can solve problems of large waste of reaction solvent acetic acid under high temperature and high pressure and being unable to take out the product TA in time during existing process of PTA production with PX.