Demetallization of liquid biomass
Methods, processes, systems, or apparatus are provided to remove contaminants such as metals and chlorine present in a pyrolysis stream to form reduced-contaminant liquid biomass. In certain embodiments, for example, a metal chelating agent is dissolved into a metal-containing pyrolysis stream condensate to form metal chelate complex, followed by filtering to obtain the reduced-contaminant liquid biomass.
1. A method to obtain a low-contaminant liquid biomass stream from a contaminant-containing pyrolysis stream, comprising:
i) contacting the pyrolysis stream with a quench stream and one or more contaminant complexing agents in a condenser to form solid complex-containing condensate; and
ii) filtering the solid complex from the condensate to form the low-contaminant liquid biomass stream;
wherein the average liquid residence time in the condenser is at least two hours.
2. The method of claim 1 , wherein at least one of the one or more contaminant complexing agents is soluble in the liquid biomass condensate.
3. The method of claim 1 , wherein at least one of the one or more contaminant complexing agents is a metal chelating agent.
4. A method to obtain a reduced-contaminant liquid biomass stream from a pyrolysis stream, the pyrolysis stream having one or more contaminants, comprising:
i) condensing a portion of the pyrolysis stream in the presence of oxalic acid at a concentration of between 0.1 and 0.4 wt. %, to form a liquid biomass condensate comprising one or more contaminant complexes; and
ii) separating the one or more contaminant complexes from the condensate to form the reduced-contaminant liquid biomass stream.
5. The method of claim 4 , wherein at least one of the one or more contaminant complexes is insoluble in the liquid biomass condensate.
6. The method of claim 5 , wherein the at least one of the one or more contaminant complexes comprises one or more of a complex of magnesium, a complex of calcium, and a complex of potassium.
7. The method of claim 4 , wherein at least one of the one or more contaminant complexes is a metal chelate.
8. The method of claim 4 , further comprising:
contacting the reduced-contaminant liquid biomass stream with a cation exchange resin.
9. The method of claim 8 , further comprising: contacting the reduced-contaminant liquid biomass stream with an anion exchange resin.
10. The method of claim 4 , wherein the reduced-contaminant liquid biomass stream has a pH of at least 2.
11. The method of claim 4 , wherein the total metal content of the liquid biomass stream is reduced by at least 25% to less than 50 ppm total weigh of alkali and alkaline earth metals relative to the pyrolysis stream.
12. The method of claim 4 , wherein the separating the one or more contaminant complexes comprises filtering at least one precipitate.
13. The method of claim 12 , wherein the filtering comprises passing the liquid biomass stream through a cake of ground biomass.
14. A method to obtain a low-contaminant liquid biomass stream from a solids-containing pyrolysis stream, comprising:
i) condensing a portion of the solids-containing pyrolysis stream to form a condensate containing suspended solids;
ii) complexing contaminants by contacting the condensate with oxalic acid at a concentration of between 0.1 and 0.4 wt. %, relative to the weight of the condensate, to form solid complex-containing condensate; and
iii) separating at least a portion of the solid complex from the condensate to form the low-contaminant liquid biomass stream.
15. The method of claim 14 , wherein the condensate containing suspended solids comprises 1-5 wt. % of the suspended solids, relative to the weight of the condensate.
16. The method of claim 14 , wherein the suspended solids comprise metals.
17. The method of claim 14 , wherein the separating at least a portion of the solid complex from the condensate comprises passing the solid complex-containing condensate through a filter to separate at least a portion of the solid complex from the condensate.