Method of reducing methanol in recycle streams in bisphenol-A production process
View Patent ↗Methods for removing methanol from acetone recycle streams during bisphenol-A production, thereby avoiding the deactivation of catalyst, by distilling an acetone-methanol-water comprising mixture such that acetone is taken overhead in form of a relatively pure distillate, and substantial portions of the methanol and the water are leaving with the bottom product.
1. A method of separating methanol from acetone recycle streams during production of bisphenol-A, comprising:
(a) introducing a product stream, including acetone, methanol, water and other components produced during a bisphenol process, as a feed at a feed point into an acetone recovery distillation column comprising a reboiler, a condenser, a bottom section, and a top section;
(b) condensing a vapor from the top section of the acetone recovery distillation column and returning at least a portion of the condensed vapor to the acetone recovery distillation column as a reflux; and
(c) setting a flow rate of the feed and a flow rate of the reflux and a heat input to the reboiler such that a bottoms product from the bottom section of the acetone recovery distillation column contains less than 10,000 ppm acetone; wherein at least 20% of the methanol of the feed to the acetone recovery distillation column is leaving with the bottoms product from the bottom section of the acetone recovery distillation column.
2. A method of separating methanol from acetone recycle streams during production of bisphenol-A, comprising:
(a) introducing a product stream, including acetone, methanol, water, and other components produced during a bisphenol process, as a feed at a feed point into an acetone recovery distillation column comprising a reboiler, a condenser, a top section, and a bottom section;
(b) introducing water as an extraction agent into the acetone recovery distillation column; and
(c) condensing a vapor from the top section of the acetone recovery distillation column and returning at least a portion of the condensed vapor to the acetone recovery distillation column as a reflux; and
(d) setting a flow rate of the feed, a flow rate of the reflux, a flow rate of the introduced water, and a heat input to the reboiler such the bottom section of the acetone recovery distillation column provides a bottoms product having less than 10,000 ppm acetone, and wherein at least 20% of the methanol leaves with the bottoms product from the bottom section of the acetone recovery distillation column.
3. The method according to claim 1 , wherein the acetone recovery distillation column comprises at least 6 trays or packing equivalent to at least 6 trays.
4. The method according to claim 1 , wherein the acetone recovery distillation column comprises from 10 to 50 trays or packing equivalent to 10 to 50 trays.
5. The method according to claim 1 , wherein the acetone recovery distillation column comprises at least 50 trays or packing equivalent to at least 50 trays.
6. The method according to claim 1 , comprising operating the acetone recovery distillation column at a pressure of 51 kPa to 203 kPa.
7. The method according to claim 1 , comprising operating the acetone recovery distillation column at atmospheric pressure.
8. The method according to claim 1 , comprising setting the reflux to be a fixed flow rate or a flow rate calculated to be a fixed multiple of the feed flow rate.
9. The method according to claim 1 , comprising setting a flow rate of the feed, and a flow rate of the reflux, and a heat input to the reboiler such that at least 40% of the methanol is leaving with the bottom product.
10. The method according to claim 1 , wherein the acetone recovery distillation column further comprises a thermocouple in the bottom section, which acts as a control thermocouple.
11. The method according to claim 1 , further comprising controlling a temperature in the bottom section to maintain an acetone concentration of less than 10,000 ppm in the bottoms product.
12. The method according to claim 1 , comprising controlling a temperature in the bottom section to maintain an acetone concentration of less than 1000 ppm in the bottoms product.
13. The method according to claim 2 , wherein the water as the extraction agent is introduced above the feed point.
14. The method according to claim 2 , wherein the introducing includes providing the water at a feed rate such that the introduced water is from 1 to 50 percent of the feed.
15. A process for producing bisphenol-A comprising:
(i) reacting phenol with acetone in the presence of at least one mercaptoamine-promoted sulfonated crosslinked polystyrene cation exchange resin to form a reaction product;
(ii) distilling the reaction product of step (a) to remove acetone, methanol, and water;
(iii) subjecting the acetone, methanol, water, and other components of step (ii) as a product stream to the separation method of claim 1 ; and
(iv) returning at least a portion of the condensed vapor from the top section of the acetone recovery distillation column to the reaction of step (i) as recovered acetone.
16. A process for producing bisphenol-A comprising:
(i) reacting phenol with acetone in the presence of at least one mercaptoamine-promoted sulfonated crosslinked polystyrene cation exchange resin to form a reaction product;
(ii) subjecting the reaction product of step (i) to a crystallization step to obtain bisphenol/phenol adduct crystals in a mother liquor;
(iii) separating the adduct crystals of step (ii) from the mother liquor;
(iv) distilling the mother liquor to remove acetone, methanol, and water;
(v) subjecting the acetone, methanol, water, and other components of step (iv) as a product stream to the separation method of claim 1 ; and
(vi) returning at least a portion of the condensed vapor from the top section of the distillation column to the reaction of step (i) as recovered acetone.