Removal of organic salts from bio-derived glycol products of polyol hydrogenolysis
A method for reducing contaminants in the production of a bio-derived glycol product of polyol hydrogenolysis is described. The method involves subjecting an aqueous, polyol product mixture (from the hydrogenolysis conversion of biologically-derived carbohydrate feedstock) to ion-exclusion chromatography to separate and reduce impurities from an eluant fraction containing a desired product, and distilling the eluant fraction to yield the desired product (e.g., propylene glycol or ethylene glycol). The reaction product mixture can be introduced into a continuous ion-exclusion chromatography system to reduce the impurities and produce in a high-throughput manner a finished otherwise commercially acceptable glycol product.
1. A method for reducing contaminants in the production of a glycol product of hydrogenolysis, the method comprises: providing a renewable or bio-derived feedstock; reacting said feedstock in a reactor to produce an aqueous, polyol product mixture; subjecting said product mixture to ion-exclusion chromatography without pH adjustment to separate and reduce salts of organic acids, from an eluant fraction containing a desired product; and distilling said eluant fraction to yield a glycol.
2. The method according to claim 1 , further comprises: subjecting said product mixture without pH neutralization to ion-exchange in addition to ion-exclusion chromatography.
3. The method according to claim 1 , wherein said polyol product mixture is generated from a reaction between renewably-sourced carbohydrates with hydrogen, and contains organic acids, salts, diols, and unreacted feedstock.
4. The method according to claim 1 , wherein said product mixture has an alkaline pH value between about 8.0 and about 12.0 when extracted initially from said reactor.
5. The method according to claim 1 , wherein said product mixture is not first neutralized with an acid.
6. The method according to claim 1 , wherein said product mixture is introduced into a continuous ion-exclusion chromatography system.
7. The method according to claim 6 , wherein said continuous system is a simulated-moving bed chromatography system.
8. The method according to claim 1 , wherein said ion-exclusion chromatography uses a resin selected from a gel-type strong acid cation (SAC) resin, gel-type strong base anion (SBA) resin, or macroporous resin.
9. The method according to claim 1 , wherein an amount of about 0.01-80 g/kg of BDO or PDO is removed per kilogram of propylene glycol recovered.
10. The method according to claim 1 , wherein said eluent fraction is introduced directly from said chromatography system to a distillation column.
11. The method according to claim 1 , wherein said distilling comprises a first column that removes alcohols, a second column that removes water, a third column that removes unreacted components or organic components having higher boiling points than that of ethylene glycol, a fourth column that removes ethylene glycol, and a fifth column that removes epoxides, esters, C 4 and higher diols, residual water, and propylene glycol.
12. A method of manufacturing propylene glycol or ethylene glycol, the method comprises providing a biologically-derived feedstock of three, five, and six carbon sugars or sugar alcohols;
converting by hydrogenolysis said feedstock in a reactor to a reaction product mixture containing polyols and impurities; subjecting said reaction product mixture to ion-exclusion chromatography to reduce said impurities from an eluant fraction containing propylene glycol or ethylene glycol; distilling said eluant fraction through a distillation system having a first column that removes alcohols, a second column that removes water, a third column that removes unreacted components or organic components having higher boiling points than that of ethylene glycol, a fourth column that removes ethylene glycol, and a fifth column that removes epoxides, esters, C 4 C 5 and higher diols, residual water and propylene glycol.
13. The method according to claim 12 , wherein said reaction product mixture is introduced without first neutralizing with acid into said ion-exclusion chromatography.
14. The method according to claim 12 , wherein said ion-exclusion chromatography is part of a continuous, simulated-moving bed system.
15. The method according to claim 12 , wherein said impurities include organic acids, salts, diols, and unreacted feedstock.
16. The method according to claim 12 , wherein bottoms content from said third distillation column is recyclable directly into said reactor.
17. The method according to claim 12 , wherein said reaction product mixture has an alkaline pH value that is not neutralized after retrieval from said reactor.
18. The method according to claim 12 , further includes extracting and introducing said elution fraction directly into said distillation system.
19. The method according to claim 12 , wherein said method about 87% to about 99% of organic acids and salts from an initial feedstock relative to said organic acids and salts in a product.
20. The method according to claim 12 , further comprises: subjecting said reaction product mixture to ion-exchange.