Desulfurized black liquor soap compositions and processes for producing
A method to purify black liquor soap (BLS) from sulfur compounds is disclosed. In the BLS desulfurization method, a BLS composition is heated in an inert atmosphere and sulfur is removed via aqueous extractions with inorganic base in the absence of other chemicals such as brine, sulfate salts and carbonate salts. The purified BLS composition exhibits favorable properties, including reduced sulfur content, lower color, and improved odor characteristics. The resulting tall oil compositions, depitched tall oil compositions, tall oil distillation fractions, and products derived therefrom also show reduced sulfur content, lower color, and improved odor characteristics.
1. A method of purifying black liquor soap (BLS) from sulfur compounds for a purified BLS having a reduced total solids sulfur contents, the method consisting essentially of:
subjecting the BLS to one or more extractions at a temperature between 60° C. to 85° C. with an aqueous alkaline solution comprising 1-15 mol/L of inorganic base, wherein the inorganic base is selected from the group consisting of NaOH, LiOH, KOH and any combination thereof, the weight ratio of the applied aqueous alkaline solution/black liquor soap mixture is greater than 1/10 and less than 20/1; and
optionally heating the BLS in an inert atmosphere or in a vacuum at a temperature of 160° C. to 320° C.;
wherein the alkaline solution is substantially free from brine, sulfate salts and carbonate salts,
wherein the total solids sulfur content of the BLS is reduced by at least 30%, and
wherein the purified BLS has a chloride content of less than 1000 ppm.
2. The method of claim 1 , wherein the aqueous alkaline solution in one or more extractions further comprises 0.01 to 4 wt. % of hydrogen peroxide.
3. The method of claim 1 , wherein the inert atmosphere is selected from the group consisting of argon, neon, helium, krypton, xenon, steam, hydrocarbons like methane, carbon monoxide, hydrogen, and nitrogen gas and combinations thereof.
4. The method of claim 1 , wherein the BLS is heated in an inert atmosphere or in a vacuum at a temperature of 180° C. to 260° C.
5. The method of claim 4 , wherein the BLS is heated in an inert atmosphere or in vacuum applied between 1 mbar and 500 mbar.
6. The method of claim 1 , further comprising: subjecting the purified BLS to acidification to adjust the pH value to between 10 and 13.
7. The method of claim 1 , wherein the total solids sulfur content of the BLS is reduced by at least 70%.
8. The method of claim 1 , wherein the total solids sulfur content of the BLS is reduced to less than 700 ppm.
9. A purified black liquor soap (BLS) having a reduced total solids sulfur content obtained by a method consisting essentially of:
subjecting the BLS to one or more extractions at a temperature between 60° C. to 85° C. with an aqueous alkaline solution comprising 1-15 mol/L of inorganic base, wherein the inorganic base is selected from the group consisting of NaOH, LiOH, KOH and any combination thereof, the weight ratio of the applied aqueous alkaline solution/black liquor soap mixture is greater than 1/10 and less than 20/1; and
optionally heating the BLS in an inert atmosphere or in a vacuum at a temperature of 160° C. to 320° C.;
wherein the alkaline solution is substantially free from brine, sulfate salts and carbonate salts,
wherein the total solids sulfur content of the BLS is reduced by at least 30%, and
wherein the purified BLS has a chloride content of less than 1000 ppm.
10. A method of making a biorenewable product, the method consisting essentially of:
purifying black liquor soap (BLS) from sulfur compounds for a purified BLS having a reduced total solids sulfur contents by:
subjecting the BLS to one or more extractions at a temperature between 60° C. to 85° C. with an aqueous alkaline solution comprising 1-15 mol/L of inorganic base, wherein the inorganic base is selected from the group consisting of NaOH, LiOH, KOH and any combination thereof, the weight ratio of the applied aqueous alkaline solution/black liquor soap mixture is greater than 1/10 and less than 20/1; and
optionally heating the BLS in an inert atmosphere or in a vacuum at a temperature in the range of 160° C. to 320° C.;
wherein the alkaline solution is substantially free from brine, sulfate salts and carbonate salts,
wherein the total solids sulfur content of the BLS is reduced by at least 30%, and
wherein the purified BLS has a chloride content of less than 1000 ppm;
acidifying the purified BLS with an acid such as sulfuric acid to obtain a crude tall oil;
subjecting the crude tall oil to one or more depitching and fractional vacuum distillation steps obtaining fractions; and
subjecting the obtained fractions to one or more processes selected from dimerization, trimerization, isomerization, aromatization, disproportionation, catalytic hydrogenation, esterification and amidation reactions.
11. The method of claim 10 , wherein the biorenewable product is a tall oil rosin ester composition, a distilled tall oil ester composition, a tall oil fatty acid ester composition, a tall oil pitch ester composition, a tall oil fatty acid dimer composition, a tall oil fatty acid trimer composition, a tall oil fatty acid monomer composition, a tall oil fatty acid dimer derived polyamide composition, a tall oil fatty acid dimer derived diamide composition, a tall oil fatty acid derived diamide composition, a tall oil fatty acid derived monoamide composition, a tall oil fatty acid monomer derived diamide composition, a tall oil fatty acid monomer derived monoamide composition, stearic acid, or isostearic acid.