Calcium hydroxide pretreatment of biomass
First Claim
1. A method for recovering calcium from a biomass pretreatment process comprising:
- a) pretreating the biomass by adding calcium oxide or hydroxide and water to the biomass to form a mixture and maintaining the mixture at ambient pressure and at greater than ambient temperature for a period of time sufficient to enhance susceptibility of the biomass to hydrolysis;
b) carbonating the pretreated biomass;
c) precipitating calcium carbonate or bicarbonate from the carbonated biomass; and
d) recovering precipitated calcium carbonate or bicarbonate.
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Abstract
Lignocellulose-containing materials are treated with lime (calcium hydroxide) and water at a relatively high temperature and for a certain period of time under certain conditions. The process variables were: lime loading which ranged from about 2 to about g Ca(OH)2 /100 g dry material; water loading which ranged from about 6 to about 19 g water/g dry material; treatment temperature which varied from about 50° C. to about 150° C.; and treatment time which varied from about 1 to about 36 hours. The effects of treatment time and temperature were interdependent.
A process for lime recovery is developed. The soluble Ca(OH)2 was washed out of the pretreated material with water and converted to insoluble CaCO3, by reacting with CO2, and was thus separated. The CaCO3 can be heated to produce CaO and CO2. The CaO is hydrated to Ca(OH)2 which can be reused as the lignocellulose treatment agent. Carbon dioxide is reused for lime recovery.
99 Citations
30 Claims
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1. A method for recovering calcium from a biomass pretreatment process comprising:
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a) pretreating the biomass by adding calcium oxide or hydroxide and water to the biomass to form a mixture and maintaining the mixture at ambient pressure and at greater than ambient temperature for a period of time sufficient to enhance susceptibility of the biomass to hydrolysis; b) carbonating the pretreated biomass; c) precipitating calcium carbonate or bicarbonate from the carbonated biomass; and d) recovering precipitated calcium carbonate or bicarbonate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method for recovering calcium from a biomass pretreatment process comprising:
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a) pretreating the biomass by adding calcium oxide or hydroxide and water to the biomass to form a mixture and maintaining the mixture at ambient pressure and at greater than ambient temperature for a period of time sufficient to enhance susceptibility of the biomass to hydrolysis; b) adding a carbonating agent to the pretreated mixture to form calcium carbonate or bicarbonate; c) heating the calcium carbonate or bicarbonate to form calcium oxide; and
recovering the calcium oxide. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30)
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Specification