Liquefaction of biomass at low pH
Inventors
Carlius, Anders • Gram, Andreas • Granath, Corinne • Jóhannesson, Haukur • Karlsson, Göran
Assignees
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Publication Number
US-9783565-B2
Publication Date
2017-10-10
Expiration Date
Abstract
The present invention relates to regulation of the p H of a liquefaction process. Presented is a method for treatment of a biomass feedstock wherein the biomass feedstock is subjected to liquefaction, at a p H of at most 4, by treatment with hot compressed liquid water (HCW) at subcritical and/or supercritical conditions to improve the conversion efficiency. The present invention is also directed to quenching of a liquefaction process according to above, preventing, minimizing or eliminating clogging and/or fouling of sticky biomass components in process equipment during processing as according to above, and to the use of additives in a biomass liquefaction process.
Core Innovation
The invention relates to a method for treatment of a biomass feedstock by subjecting the biomass feedstock to liquefaction using hot compressed liquid water (HCW) at a subcritical condition. The liquefaction is carried out at a temperature of from 330°C to below 374°C and at a pH below 3.0, with a reaction time below 1 minute.
The disclosed process architecture includes pH regulation using added acids, including inorganic acids, to control conversion. The described approach includes lowering pH to increase monomer yields in cellulose examples and reducing degradation output through NaOH pH adjustment toward higher pH values.
The disclosed process architecture includes quenching and downstream handling intended to address lignin solidification, clogging, and fouling. Quenching strategies include cold water injection to rapidly solidify lignin and prevent clogging/fouling, as well as alkaline washing/quenching using caustic solutions to increase lignin solubility and stop or decelerate degradation, with continuous flow and sequential at least two reactors with liquid-phase separation after each reactor.
Claims Coverage
The independent claim covers a biomass treatment method defined by HCW liquefaction under subcritical conditions with three main constraints: temperature between 330°C and below 374°C, pH below 3.0, and reaction time below 1 minute. The claim set further adds inventive refinements including selected inorganic acids, sequential at least two reactors with intermediate liquid-phase separation, continuous flow operation, a narrowed reaction-time window, and water-injection quenching with a post-quenching temperature threshold.
HCW subcritical liquefaction at constrained temperature, acidic pH, and short reaction time
Subjecting a biomass feedstock to liquefaction by treatment with hot compressed liquid water (HCW) at a subcritical condition at a temperature of from 330°C to below 374°C, at a pH below 3.0, and for a reaction time below 1 minute.
Selected inorganic acid options for the acidic liquefaction conditions
The liquefaction uses inorganic acids selected from sulfuric acid, sulfonic acid, phosphoric acid, phosphonic acid, nitric acid, nitrous acid, hydrochloric acid, hydrofluoric acid, hydrobromic acid, and hydroiodic acid, or any combination thereof.
Sequential reactors with intermediate liquid-phase separation
The liquefaction is carried out sequentially in at least two separate reactors, with a liquid-phase separation performed after each reactor.
Continuous flow HCW liquefaction
The liquefaction is carried out in a continuous flow system.
Narrow reaction-time window for the liquefaction
The liquefaction reaction time is set to between 1 and 45 seconds.
Water-injection quenching with post-quenching temperature constraint
A monomer and/or oligomer sugar mixture is quenched by injecting water so that a post-quenching temperature is below 165°C.
Overall, the claim set centers on subcritical HCW liquefaction with acidic pH and very short reaction time, and extends coverage via specific acid selections, sequential multi-reactor processing with intermediate liquid-phase separation, continuous flow operation, a defined reaction-time range, and quenching by water injection with a post-quenching temperature threshold.
Stated Advantages
Improved conversion efficiency is stated in the described disclosure.
Possible temperature reduction is stated in the described disclosure.
Short residence/reaction times are emphasized.
Reduced clogging and fouling are stated, including clogging-delay benefits from water injection and fouling reduction from alkaline NaOH addition or pulse washing.
In cellulose examples, lower pH increases monomer yields.
NaOH pH adjustment reduces degradation output.
Alkaline washing/quenching increases lignin solubility and stops or decelerates degradation.
Documented Applications
Biomass liquefaction, including cellulose examples, to produce a monomer and/or oligomer sugar mixture solution while managing lignin solidification, clogging, and fouling.
Continuous flow tube reactor processing with evaluation of clogging/fouling delay behavior using water injection.
Sequential processing with at least two reactors and liquid-phase separation after each reactor as an application architecture described in the document.
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