# US 9,518,024 B2 · Method and system for preparing caprolactam > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,024 B2 - Document ID: US9518024B2 - Status: Granted - Kind: B2 - Application number: 14/996,723 - Filed: 2016-01-15 - Published: 2016-08-18 - Granted: 2016-12-13 - Earliest claimed: 2015-02-13 - Assignees: China Petrochemical Development Corporation - Applicants: China Petrochemical Development Corporation - Inventors: Yung-Shun Kung; Jih-Dar Hwang; Yao-Ching Tsai - Web page: https://patentgrep.com/patent/US9518024B2 ## CPC - C07D 223/10: attached in position 2 - B01D 3/148: {in combination with at least one evaporator} - B01D 11/0488: {Flow sheets} - B01J 8/02: with stationary particles, e.g. in fixed beds - B01J 19/245: {placed in series} - B01J 2208/02: with stationary particles - B01J 2219/24: Stationary reactors without moving elements inside - C07D: HETEROCYCLIC COMPOUNDS (macromolecular compounds C08) - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS ## Abstract The present disclosure provides a method for preparing a caprolactam and the method includes steps of subjecting cyclohexanone oxime and sulfuric acid to a Beckmann rearrangement reaction to obtain a rearrangement mixture; neutralizing the rearrangement mixture and extracting the neutralized rearrangement mixture using an organic solvent sequentially; and subjecting the extracted organic solution to a hydrogenation reaction so as to simplify the process to produce a high quality caprolactam. ## Claims ### Claim 1 A method for preparing caprolactam, comprising steps of: (a) subjecting cyclohexanone oxime and sulfuric acid to a Beckmann rearrangement reaction to obtain a rearrangement mixture; (b) neutralizing the rearrangement mixture with a base to obtain a first crude caprolactam solution rich in caprolactam and a second crude caprolactam solution rich in sulfate; (c) extracting at least the first crude caprolactam solution with an organic solvent to obtain a caprolactam organic solution; (d) mixing the caprolactam organic solution with hydrogen to perform a hydrogenation reaction in a hydrogenation reactor having a hydrogenation catalyst, wherein a weight hourly space velocity of the caprolactam organic solution is 1 to 20 per hour, a feeding hydrogen flow rate is NM3 0.01 to 0.15 NM3 per hour per cubic meter of the caprolactam organic solution, and a hydrogen gauge pressure of an outlet of the hydrogenation reactor is 3 kg/cm2 to 20 kg/cm2; and (e) purifying the hydrogenated caprolactam organic solution, wherein the purification includes steps of evaporation and distillation to separate the caprolactam. ### Claim 2 (depends on 1) The method according to claim 1, further comprising extracting the second crude caprolactam solution with the organic solvent to obtain the caprolactam organic solution. ### Claim 3 (depends on 2) The method according to claim 2, wherein the first crude caprolactam solution and the second crude caprolactam solution are extracted with the organic solvent simultaneously. ### Claim 4 (depends on 1) The method according to claim 1, wherein the organic solvent is an aromatic hydrocarbon or a halogenated hydrocarbon. ### Claim 5 (depends on 4) The method according to claim 4, wherein the organic solvent is toluene, benzene or dichloroethane. ### Claim 6 (depends on 1) The method according to claim 1, wherein the base is ammonia. ### Claim 7 (depends on 1) The method according to claim 1, further comprising, after step (c), adjusting the electric conductivity of the caprolactam organic solution to 5 μmoh/cm to 100 μmoh/cm with a base aqueous solution. ### Claim 8 (depends on 1) The method according to claim 1, further comprising, after step (c), removing at least a portion of the organic solvent. ### Claim 9 (depends on 1) The method according to claim 1, wherein the hydrogenation catalyst comprises a carrier and an active metal carried on the carrier, and wherein the carrier is one selected from the group consisting of alumina, carbon and silica. ### Claim 10 (depends on 9) The method according to claim 9, wherein the active metal is one selected from the group consisting of ruthenium, rhodium, palladium, platinum and nickel. ### Claim 11 (depends on 9) The method according to claim 9, wherein an amount of the active metal is 5 wt % to 85 wt %. ### Claim 12 (depends on 1) The method according to claim 1, wherein the reaction temperature of the hydrogenation reaction is 50° C. to 180° C. ### Claim 13 (depends on 1) The method according to claim 1, further comprising, prior to step (e) or during step (e), adding at least one alkali metal hydroxide in the hydrogenated caprolactam organic solution. ### Claim 14 (depends on 13) The method according to claim 13, wherein the alkali metal hydroxide is at least one selected from the group consisting of sodium hydroxide and potassium hydroxide. ### Claim 15 (depends on 13) The method according to claim 13, wherein an amount of the alkali metal hydroxide is no more than 20 milliequivalent of the alkali metal hydroxide per kilogram of the hydrogenated caprolactam organic solution.