Method for production of aqueous (meth)acrylic acid
The present invention relates to recovery of aqueous (meth)acrylic acid by condensation of a (meth)acrylic acid-containing stream to produce aqueous (meth)acylic acid having a higher concentration of (meth)acrylic acid and a lower concentration of formaldehyde, i.e., not more than 0.1 weight %, than the aqueous (meth)acrylic acid produced using hithertofore known separation methods. The (meth)acrylic acid-containing stream may be the raw product stream of catalytic oxidation at least one C 2 -C 4 alkane or alkene.
1. A method for producing aqueous acrylic acid from a gaseous material stream comprising:
a) providing a gaseous stream to a condenser, wherein the gaseous material stream comprises at least acrylic acid, water, formaldehyde; and
b) operating the condenser and producing a gaseous vent stream comprising uncondensed components, and a condensed aqueous acrylic acid stream comprising acrylic acid,
wherein the aqueous acrylic acid stream comprises not more than 0.1% by weight formaldehyde, based on the total weight of the aqueous acrylic acid stream, and wherein the balance of the formaldehyde originally in the gaseous material stream is contained in the gaseous vent stream.
2. The method of claim 1 , wherein the aqueous acrylic acid stream comprises between 75% and 95% by weight acrylic acid, based on the total weight of the aqueous acrylic acid stream.
3. The method of claim 1 wherein said aqueous acrylic acid stream comprises not more than 0.05% by weight formaldehyde.
4. The method of claim 1 wherein said aqueous acrylic acid stream comprises not more than 0.01% by weight formaldehyde.
5. The method of claim 1 further comprising:
c) stripping the aqueous acrylic acid stream in an acrolein removal column to obtain a reduced-acrolein content aqueous acrylic acid stream and a condensate stream comprising acrolein, and
d) recycling said condensate stream comprising acrolein to the acrylic acid condenser.
6. The method of claim 1 further comprising oxidizing at least one hydrocarbon selected from propylene and propane in a catalytic vapor-phase shell-and-tube reaction system to produce said gaseous material stream comprising acrylic acid, water and formaldehyde.
7. The method of claim 1 , wherein the gaseous stream further comprises non-condensable materials which have a boiling point, at atmospheric pressure, of no greater than −40° C.
8. The method of claim 1 , wherein the gaseous material stream has a temperature of from 50° C. to 450° C.