Process for inhibiting the undesired free-radical polymerization of acrylic acid present in a liquid phase P, wherein the acrylic acid content of P is at least 10% by weight, the liquid phase P comprises in the range from 25 to 1000 ppmw of glyoxal based on the weight of the acrylic acid present in P and the liquid phase P is admixed with protoanemonine in an amount that results in a protoanemonine content in the range from 0.5 to 100 ppmw based on the weight of the acrylic acid present in P, and a liquid phase P, wherein the acrylic acid content of P is at least 10% by weight and the liquid phase P comprises in the range from 25 to 1000 ppmw of glyoxal and in the range from 0.5 to 100 ppmw of protoanemonine, in each case based on the weight of the acrylic acid present in P.

Process for inhibiting the undesired free-radical polymerization of acrylic acid present in a liquid phase P, wherein the acrylic acid content of P is at least 10% by weight, the liquid phase P comprises in the range from 25 to 1000 ppmw of glyoxal based on the weight of the acrylic acid present in P and the liquid phase P is admixed with protoanemonine in an amount that results in a protoanemonine content in the range from 0.5 to 100 ppmw based on the weight of the acrylic acid present in P, and a liquid phase P, wherein the acrylic acid content of P is at least 10% by weight and the liquid phase P comprises in the range from 25 to 1000 ppmw of glyoxal and in the range from 0.5 to 100 ppmw of protoanemonine, in each case based on the weight of the acrylic acid present in P.

Provided is a method for producing acrylic acid, the method including: preparing a reaction product containing acrylic acid by supplying lactic acid to a reactor and performing a dehydration reaction; supplying a reactor discharge stream containing the reaction product to a cooling tower and condensing the result to transfer a lower discharge stream including a condensate to an acrylic acid purification unit and supplying a non-condensate discharged as an upper discharge stream to a distillation tower; and, in the distillation tower, circulating the lower discharge stream containing acrylic acid to the cooling tower, and removing acetaldehyde from the upper discharge stream.

Provided is a method for producing acrylic acid, the method including: preparing a reaction product containing acrylic acid by supplying lactic acid to a reactor and performing a dehydration reaction; supplying a reactor discharge stream containing the reaction product to a cooling tower and condensing the result to transfer a lower discharge stream including a condensate to an acrylic acid purification unit and supplying a non-condensate discharged as an upper discharge stream to a distillation tower; and, in the distillation tower, circulating the lower discharge stream containing acrylic acid to the cooling tower, and removing acetaldehyde from the upper discharge stream.

An improved process can be used for the production of methacrylates, in particular methacrylic acid and/or methyl methacrylate (MMA). Specific embodiments of this process can be used for the safe and efficient production of these products from C-4-based raw materials, in particular those based on isobutylene or tort-butanol as raw materials. With this novel process, it is possible to operate such processes for a longer period of time without any safety or cleaning related shutdowns. This makes it possible to carry out such processes as simple, economic, and environmentally friendly as possible.

An improved process can be used for the production of methacrylates, in particular methacrylic acid and/or methyl methacrylate (MMA). Specific embodiments of this process can be used for the safe and efficient production of these products from C-4-based raw materials, in particular those based on isobutylene or tort-butanol as raw materials. With this novel process, it is possible to operate such processes for a longer period of time without any safety or cleaning related shutdowns. This makes it possible to carry out such processes as simple, economic, and environmentally friendly as possible.

An object of the present invention is to provide a catalyst ensuring that when a gas-phase catalytic oxidation reaction of a material substance is conducted using a catalyst to produce a target substance, the pressure loss and coking are suppressed and the target substance can be produced in high yield. The present invention is related to a ring-shaped catalyst having a straight body part and a hollow body part, which is used when a gas-phase catalytic oxidation reaction of a material substance is conducted to produce a target substance, wherein a length of the straight body part is shorter than a length of the hollow body part and at least at one end part, a region from an end part of the straight body part to an end part of the hollow body part is concavely curved.

An object of the present invention is to provide a catalyst ensuring that when a gas-phase catalytic oxidation reaction of a material substance is conducted using a catalyst to produce a target substance, the pressure loss and coking are suppressed and the target substance can be produced in high yield. The present invention is related to a ring-shaped catalyst having a straight body part and a hollow body part, which is used when a gas-phase catalytic oxidation reaction of a material substance is conducted to produce a target substance, wherein a length of the straight body part is shorter than a length of the hollow body part and at least at one end part, a region from an end part of the straight body part to an end part of the hollow body part is concavely curved.

An improved process can be used for the production of methacrylates, in particular methacrylic acid and/or methyl methacrylate (MMA). Specific embodiments of this process can be used for the safe and efficient production of these products from C-4-based raw materials, in particular those based on isobutylene or tert-butanol as raw materials. With this novel process, it is possible to operate such processes for a longer period of time without any safety or cleaning related shutdowns. This makes it possible to carry out such processes as simple, economic, and environmentally friendly as possible.

An improved process can be used for the production of methacrylates, in particular methacrylic acid and/or methyl methacrylate (MMA). Specific embodiments of this process can be used for the safe and efficient production of these products from C-4-based raw materials, in particular those based on isobutylene or tert-butanol as raw materials. With this novel process, it is possible to operate such processes for a longer period of time without any safety or cleaning related shutdowns. This makes it possible to carry out such processes as simple, economic, and environmentally friendly as possible.