Thermochemical Processing of Algal Biomass

Abstract

A thermolysis process for treating algal biomass, consisting substantially of dried algal cells, in which the algal biomass is heated from ambient to 460° C. in a flowing stream that contains one or more of carbon dioxide, acetic acid or other organic acids and that produces a condensable hydrocarbon product whose mass yield is greater than the dry, ash-free mass fraction of lipids in the starting algal biomass and whose higher enthalpy of combustion exceeds 25 MJ/kg plus a char, and a hydrocarbon-laden gaseous product. In another feature, the present invention includes heating the previously dried, algal biomass in a readily available, waste acid gas, such as flue gas that is rich in carbon dioxide, or to intimately mix the algal biomass with a solid acid, such as a protonated, large pore zeolite, and then heating the mixture in a non-oxidizing sweep gas.

1 . A thermolysis process for treating algal biomass, consisting substantially of dried algal cells, in which the algal biomass is heated from ambient to 460° C. in a flowing stream that contains one or more of carbon dioxide, acetic acid or other organic acids and that produces a condensable hydrocarbon product whose mass yield is greater than the dry, ash-free mass fraction of lipids in the starting algal biomass and whose higher enthalpy of combustion exceeds 25 MJ/kg plus a char, and a hydrocarbon-laden gaseous product. 
     
     
         2 . A thermolysis process for treating algal biomass, consisting substantially of dried algal cells, in which the algal biomass is intimately mixed with a solid acid catalyst and is heated from ambient to 460° C. in a flowing gas stream that produces a condensable hydrocarbon product whose mass yield is greater than the dry, ash-free mass fraction of lipids in the starting algal biomass and whose higher enthalpy of combustion exceeds 25 MJ/kg, plus a char, and a hydrocarbon-laden gaseous product. 
     
     
         3 . The process of  claim 1  in which the thermolysis products are collected fractionally as the temperature of the biomass increases. 
     
     
         4 . The process of  claim 2  in which the thermolysis products are collected fractionally as the temperature of the biomass increases. 
     
     
         5 . The process of  claim 1  in which the condensed product stream contains:
 a. Indole;   b. Methyl indole;   c. Succinimide;   d. Propylcyclohexanol;   e. Dodecane;   f. Dodecene;   g. Tridecene;   h. Pentadecene;   i. Heptadecene;   j. Nonadecene; and   k. at least 0.1 wt % sulfur.   
     
     
         6 . The process of  claim 2  in which the condensed product stream contains:
 a. Methylphenol;   b. Indole;   c. Methylindole;   d. Dimethylphenol;   e. Ethylphenol;   f. Succinimide;   g. Propylcyclohexanol;   h. Trimethylbicycloheptane;   i. Succinimide;   j. Propylcyclohexanol;   k. Trimethylbicycloheptane;   I. Dodecane;   m. Pentadecene;   n. Heptadecene;   o. Phytol;   p. Amobarbital;   q. Pentobarbital; and   r. at least 0.1 wt % sulfur.   
     
     
         7 . The process of  claim 1  in which condensed product fractions produced at temperatures less than or equal to 50° C. contain:
 a. Indole;   b. Methylindole;   c. Succinimide;   d. Propylcyclohexanol; and   e. Trimethylbicycloheptane   
     
     
         8 . The process of  claim 2  in which condensed product fractions produced at temperatures less than or equal to 50° C. contain:
 a. Methylphenol;   b. Indole;   c. Methylindole;   d. Dimethylphenol;   e. Ethylphenol;   f. Succinimide;   g. Propylcyclohexanol;   h. Trimethylbicycloheptane;   i. Dodecane;   j. Heptadecene; and   k. Phytol   
     
     
         9 . The process of  claim 1  in which the temperature of the algal biomass is raised using waste heat from an industrial process. 
     
     
         10 . The process of  claim 2  in which the temperature of the algal biomass is raised using waste heat from an industrial process. 
     
     
         11 . The process of  claim 1  in which the sweep gas comes from the flue gas of another industrial process and is deoxygenated by reacting it with the char produced in the process of  claim 1 . 
     
     
         12 . The process of  claim 2  in which the sweep gas comes from the flue gas of another industrial process and is deoxygenated by reacting it with the char produced in the process of  claim 2 . 
     
     
         13 . The process integration of  claim 9  in which the partner industrial process receives greenhouse gas credits in proportion to the fuel whose heat has been used to thermolyze the algal biomass. 
     
     
         14 . The process integration of  claim 10  in which the partner industrial process receives greenhouse gas credits in proportion to the fuel whose heat has been used to thermolyze the algal biomass. 
     
     
         15 . The process integration of  claim 11  in which the partner industrial process receives greenhouse gas credits in proportion to the fuel whose heat has been used to thermolyze the algal biomass. 
     
     
         16 . The process integration of  claim 12  in which the partner industrial process receives greenhouse gas credits in proportion to the fuel whose heat has been used to thermolyze the algal biomass.