# US 10,479,751 B2 · Process for preparing acrylic acid > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,479,751 B2 - Document ID: US10479751B2 - Status: Granted - Kind: B2 - Application number: 14/915,929 - Filed: 2014-08-11 - Published: 2016-09-08 - Granted: 2019-11-19 - Earliest claimed: 2013-09-02 - Assignees: Evonik Degussa GmbH - Applicants: Evonik Degussa GmbH - Inventors: Jürgen Mosler; Christian Psiorz; Franz-Felix Kuppinger; Raphael Schriewer; Arnd Bruhns; Armin Rix; Peter Kreis; Ralf Meier; James Edward Elder - Web page: https://patentgrep.com/patent/US10479751B2 ## CPC - C07C 51/252: {of propene, butenes, acrolein or methacrolein} - B01D 3/009: {in combination with chemical reactions} - B01D 3/143: {by two or more of a fractionation, separation or rectification step} - B01D 3/16: Fractionating columns in which vapour bubbles through liquid (packing elements B01J19/30, B01J19/32) - B01D 3/163: {Plates with valves} - B01D 3/22: with horizontal sieve plates or grids; Construction of sieve plates or grids - B01J 10/00: Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor (B01J19/08 takes precedence; separation, e.g. distillation, also combined with chemical reactions B01D, {e.g. B01D3/009}) - B01J 19/30: Loose or shaped packing elements, e.g. Raschig rings or Berl saddles, for pouring into the apparatus for mass or heat transfer - B01L 3/16: Retorts - C07C 51/48: by liquid-liquid treatment - C07C 57/04: Acrylic acid; Methacrylic acid - B01J 2219/3325: Counter-current flow - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS - 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 - B01L: CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE ## Abstract The present invention provides an apparatus comprising a feed arranged below the middle of the apparatus, a quenching agent inlet arranged above the feed, an outlet arranged below the feed and a draw arranged above the quenching agent inlet, the apparatus having a region provided with one or more packing elements, wherein at least one means which ensures the formation of a liquid layer having a height of at least 1 cm is present between the quenching agent inlet and a packing element present between the quenching agent inlet and feed. The present invention also provides a process for preparing acrylic acid, which includes a step of oxidizing acrolein, wherein the reaction mixture obtained in this oxidation is contacted with water as quenching agent in an inventive apparatus, and a composition obtainable as bottom product in the process according to the invention, comprising acrylic acid and water. ## Claims ### Claim 1 An apparatus consisting essentially of a feed containing a reaction mixture arranged below the middle of the apparatus, a quenching agent inlet arranged above the feed, an outlet arranged below the feed and a draw arranged above the quenching agent inlet, the apparatus having, between the quenching agent inlet and the feed containing the reaction mixture, a region provided with one or more packing elements, wherein 2 or 3 sieve trays or ripple trays which ensure the formation of a liquid layer having a height of at least 1 cm is present between the quenching agent inlet and a packing element present between the quenching agent inlet and feed containing the reaction mixture, the liquid layer being arranged in the apparatus such that gaseous substances which pass through the feed containing the reaction mixture into the apparatus have to pass through the liquid layer in order to get into the top of the apparatus. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the liquid layer has a height of 2 to 10 cm. ### Claim 3 (depends on 1) The apparatus according to claim 1 wherein the packing element is a structured packing element or a fabric packing element. ### Claim 4 (depends on 1) The apparatus according to claim 1, wherein the packing element has a height of 50 to 85% of the internal height of the apparatus. ### Claim 5 (depends on 1) The apparatus according to claim 1, wherein a distributor present between a lowermost sieve trays or ripple trays and the uppermost packing element distributes the liquid phase flowing downward from the lowermost sieve trays or ripple trays over the packing element. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein a collector arranged between the lowermost sieve trays or ripple trays and distributor collects the liquid phase flowing downward from the lowermost sieve trays or ripple trays and feeds liquid phase to the distributor. ### Claim 7 A process for preparing acrylic acid, including a step of oxidizing acrolein, wherein the reaction mixture obtained in this oxidation is contacted with water as quenching agent in an apparatus consisting essentially of a feed containing a reaction mixture arranged below the middle of the apparatus, a quenching agent inlet arranged above the feed, an outlet arranged below the feed and a draw arranged above the quenching agent inlet, the apparatus having, between the quenching agent inlet and the feed containing the reaction mixture, a region provided with one or more packing elements, wherein 2 or 3 sieve trays or ripple trays which ensure the formation of a liquid layer having a height of at least 1 cm is present between the quenching agent inlet and a packing element present between the quenching agent inlet and feed containing the reaction mixture, the liquid layer being arranged in the apparatus such that gaseous substances which pass through the feed containing the reaction mixture into the apparatus have to pass through the liquid layer in order to get into the top of the apparatus. ### Claim 8 (depends on 7) The process according to claim 7, wherein the ratio of the volume flow rates of the quenching agent which is fed to the apparatus and the reaction mixture which is fed to the apparatus is from 1:2 to 1:20. ### Claim 9 (depends on 7) The process according to claim 7, wherein the temperature of the liquid phase on the sieve trays or ripple trays is from 50° C. to 100° C. ### Claim 10 (depends on 7) The process according to claim 7, wherein the pressure differential between the pressure measured at the top of the apparatus and the pressure measured in the gas space of the liquid phase in the bottom of the apparatus is from 10 mbar to 60 mbar. ### Claim 11 (depends on 7) The process according to claim 7 wherein the apparatus is fed with 210 to 380 kg of reaction mixture per hour per m3 of apparatus volume. ### Claim 12 (depends on 2) The apparatus according to claim 2, wherein the liquid has a height of 3 to 8 cm. ### Claim 13 (depends on 3) The apparatus according to claim 3, wherein the packing element is a structured packing. ### Claim 14 (depends on 8) The process according to claim 8, wherein the ratio of the volume flow rates of the quenching agent which is fed to the apparatus and the reaction mixture which is fed to the apparatus is from 1:5 to 1:10. ### Claim 15 (depends on 9) The process according to claim 9, wherein the temperature of the liquid phase on the sieve trays or ripple trays is from 70° C. to 80° C. ### Claim 16 (depends on 10) The process according to claim 10, wherein the apparatus is operated in such a way that the pressure differential between the pressure measured at the top of the apparatus and the pressure measured in the gas space of the liquid phase in the bottom of the apparatus is from 30 mbar to 40 mbar.