Production of caprolactam, used in nylon manufacture, comprises gas-phase rearrangement of cyclohexanone oxime on a silica or zeolite catalyst treated or reactivated with acid

Production of epsilon-caprolactam (I) comprises gas-phase rearrangement of cyclohexanone oxime (II) on a solid catalyst comprising: (i) silica that has been treated or reactivated with an acidic aqueous solution of pH 1-6; or (ii) a crystalline zeolite that has been treated or reactivated with an acidic aqueous solution of pH 1-3. Independent claims are also included for the following: (1) A process for treating a solid catalyst with an acidic aqueous solution, comprising: (i) treating silica with a solution of pH 1-6; or (ii) treating a crystalline zeolite with a solution of pH 1-3. (2) A process for reactivating a solid catalyst that is losing its activity in the gas-phase production of (I) from (II), comprising (i) treating silica with an acidic aqueous solution of pH 1-6; or (ii) treating a crystalline zeolite with an acidic aqueous solution of pH 1-3. (3) A process for producing (I) from (II) using a silica with adjacent silanol groups (term not defined). Production of iota -caprolactam (I) comprises gas-phase rearrangement of cyclohexanone oxime (II) on a solid catalyst comprising: (i) silica that has been treated or reactivated with an acidic aqueous solution of pH 1-6; or (ii) a crystalline zeolite that has been treated or reactivated with an acidic aqueous solution of pH 1-3. Independent claims are also included for the following: (1) A process for treating a solid catalyst with an acidic aqueous solution, comprising: (i) treating silica with a solution of pH 1-6; or (ii) treating a crystalline zeolite with a solution of pH 1-3. (2) A process for reactivating a solid catalyst that is losing its activity in the gas-phase production of (I) from (II), comprising (i) treating silica with an acidic aqueous solution of pH 1-6; or (ii) treating a crystalline zeolite with an acidic aqueous solution of pH 1-3. (3) A process for producing (I) from (II) using a silica with adjacent silanol groups (term not defined). Ein neues Verfahren zur Herstellung von epsilon-Caprolactam aus Cyclohexanonoxim in der Gasphase unter Verwendung eines festen Katalysators wird bereitgestellt. Das Verfahren wird unter Verwendung von mit einer wässrigen sauren Lösung mit einem pH-Wert von 1 bis 6 behandeltem Siliciumdioxid oder einem mit einer wässrigen sauren Lösung mit einem pH-Wert von 1 bis 3 behandelten kristallinen Zeolith durchgeführt. DOLLAR A Gemäß dem Verfahren können ein kristalliner Zeolith und Siliciumdioxid die Umwandlung von Cyclohexanonoxim und die Selektivität f