The invention relates to a thermal conversion vessel (200) used during amidification step of acetone cyanohydrin (ACH), in the industrial process for production of a methyl methacrylate (MMA) or methacrylic acid (MAA). The thermal conversion vessel (200) is used for converting an hydrolysis mixture of α-hydroxyisobutyramide (HIBAM), α-sulfatoisobutyramide (SIBAM), 2-methacrylamide (MACRYDE) and methacrylique acid (MAA), into a mixture of 2-methacrylamide (MACRYDE). It comprises:—at least one compartment (C1, C2, C3, . . . Ci) comprising an inner wall (206a, 206b, . . . 206i) separating said compartment into two communicating parts (C1a, C1b) by a passage provided between the bottom of said vessel and said inner wall,—said compartment having a space above said inner wall, for separating gas phase from liquid phase during thermal conversion,—said compartment being connected to an outlet valve (204a, 204b, . . . 204i). Such vessel allows obtaining a high yield thermal conversion in very safe conditions.

The invention relates to a thermal conversion vessel (200) used during amidification step of acetone cyanohydrin (ACH), in the industrial process for production of a methyl methacrylate (MMA) or methacrylic acid (MAA). The thermal conversion vessel (200) is used for converting an hydrolysis mixture of α-hydroxyisobutyramide (HIBAM), α-sulfatoisobutyramide (SIBAM), 2-methacrylamide (MACRYDE) and methacrylique acid (MAA), into a mixture of 2-methacrylamide (MACRYDE). It comprises:—at least one compartment (C1, C2, C3, . . . Ci) comprising an inner wall (206a, 206b, . . . 206i) separating said compartment into two communicating parts (C1a, C1b) by a passage provided between the bottom of said vessel and said inner wall,—said compartment having a space above said inner wall, for separating gas phase from liquid phase during thermal conversion,—said compartment being connected to an outlet valve (204a, 204b, . . . 204i). Such vessel allows obtaining a high yield thermal conversion in very safe conditions.

The invention relates to a thermal conversion vessel (200) used during amidification step of acetone cyanohydrin (ACH), in the industrial process for production of a methyl methacrylate (MMA) or methacrylic acid (MAA). The thermal conversion vessel (200) is used for converting an hydrolysis mixture of α-hydroxyisobutyramide (HIBAM), α-sulfatoisobutyramide (SIBAM), 2-methacrylamide (MACRYDE) and methacrylique acid (MAA), into a mixture of 2-methacrylamide (MACRYDE). It comprises:—at least one compartment (C1, C2, C3, . . . Ci) comprising an inner wall (206a, 206b, . . . 206i) separating said compartment into two communicating parts (C1a, C1b) by a passage provided between the bottom of said vessel and said inner wall,—said compartment having a space above said inner wall, for separating gas phase from liquid phase during thermal conversion,—said compartment being connected to an outlet valve (204a, 204b, . . . 204i). Such vessel allows obtaining a high yield thermal conversion in very safe conditions.

Fouling of an MMA process is reduced by acidifying a stream comprising recycled components.

Fouling of an MMA process is reduced by acidifying a stream comprising recycled components.

Fouling of an MMA process is reduced by acidifying a stream comprising recycled components.

Fouling of an MMA process is reduced by strategically removing an aqueous slip stream.

Fouling of an MMA process is reduced by strategically removing an aqueous slip stream.

Fouling of an MMA process is reduced by strategically removing an aqueous slip stream.

The present invention relates to a process for preparing alpha-hydroxycarboxylic esters proceeding from hydrogen cyanide, wherein the ammonia formed in the step of alcoholysis of the corresponding alpha-hydroxycarboxamide is recycled into a hydrogen cyanide preparation process after a purification step.