Method for processing effluent from chloromethylation of vinyl aromatic polymers
AssigneeDow Global Technologies LLC
InventorsWilliam I. Harris, Bruce S. Holden, Doreen C. Keptner, David C. McDonald
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Abstract
A method for processing effluent from a chloromethylation of a vinyl aromatic polymer wherein the effluent comprises catalyst and volatile organics, and wherein the method comprising the steps of: 1) deactivating at least a portion of the catalyst; 2) distilling the effluent; 3) adding caustic to the effluent; and 4) distilling the effluent.
Claims16
A method for processing effluent from a chloromethylation of a vinyl aromatic polymer wherein the effluent comprises catalyst and volatile organics, and wherein the method comprising the steps of:
- 1) deactivating at least a portion of the catalyst;
- 2) distilling the effluent;
- 3) adding caustic to the effluent;
- and
- 4) distilling the effluent.
The method according to any preceding claim wherein:
- 1) the step of deactivating at least a portion of the catalyst comprises adding at least one of the following constituents to the effluent:
- hydrochloric acid, methanol and water;
- 2) the first distillation step is conducted at a distillation temperature less than about 80° C.;
- and
- 3) the step of adding caustic comprises adding a sufficient quantity to raise the initial pH of the effluent to at least about 5.
The method according to any preceding claim wherein:
- 1) the step of deactivating at least a portion of the catalyst comprises adding an aqueous solution comprising from about 1 to 40 weight percent hydrochloric acid to the effluent;
- 2) the first distillation step is conducted at a distillation temperature less than about 70° C.;
- and
- 3) the step of adding caustic comprises adding an aqueous solution comprising sodium hydroxide to the effluent in sufficient quantity to raise the initial pH of the effluent to at least about 8.
The method according to any preceding claim wherein the second distillation step is conducted at a distillation temperature less than about 110° C.
The method according to any preceding claim wherein the second distillation step is conducted at a distillation temperature above about 80° C.
The method according to any preceding claim wherein the second distillation step is conducted under conditions to lower the total volatile organic content of the effluent to less than about 10 weight percent.
The method according to any preceding claim wherein the volatile organics comprise methanol, and the second distillation step is conducted under conditions to lower the total methanol content of the effluent to less than about 3 weight percent.
The method according to any preceding claim wherein the volatile organics comprise formaldehyde, and the second distillation step is conducted under conditions to lower the total formaldehyde content of the effluent to less than about 3 weight percent.
The method according to any preceding claim wherein the catalyst comprises at least one of:
- aluminum chloride, zinc chloride, ferric chloride and ferric oxide;
- and the volatile organics comprise at least one of:
- chloromethyl methyl ether (CMME), methylal, methanol, and formaldehyde.
The method according to any preceding claim wherein caustic comprises at least one of:
- sodium hydroxide, potassium hydroxide and calcium hydroxide.
The method according to any preceding claim wherein the first distillation step comprises a multi-stage process comprising a first evaporation conducted at about standard atmospheric pressure and a temperature up to about 60° C. followed by one or more subsequent evaporations conducted at a reduced pressure from about 10 to 90 kPa and temperature less than about 60° C.
The method according to any preceding claim wherein at least a portion of the step of deactivating at least a portion of the catalyst and the first distillation step are conducted concurrently.
The method according to any preceding claim wherein at least a portion of the step of adding caustic and the second distillation step are conducted concurrently.
The method according to any preceding claim further comprising the step of filtering catalyst and spend catalyst from the effluent after the addition of caustic but prior to the second distillation step.
A method for processing effluent from a chloromethylation of a vinyl aromatic polymer wherein the effluent comprises catalyst, methanol and chloromethyl methyl ether, and wherein the method comprises the steps of:
- 1) adding an aqueous solution of hydrochloric acid in sufficient quantity to deactivate at least a majority portion of the catalyst;
- 2) distilling the effluent at a distillation temperature less than about 80° C.;
- 3) adding an aqueous solution of sodium hydroxide to the effluent in sufficient quantity to raise the initial pH of the effluent to at least about 8;
- and
- 4) distilling the effluent at a distillation temperature above about 80° C.
Dependencies are inferred from the claim text.