Economical methods for performing oxidative catalytic pretreatment of plant biomass using a single-stage two oxidant process
Inventors
Hegg, Eric L. • Yuan, Zhaoyang • Hodge, David B. • Stahl, Shannon S. • Bals, Bryan D.
Assignees
Montana State University Bozeman • Michigan State University MSU • Wisconsin Alumni Research Foundation
Publication Number
US-11859145-B1
Publication Date
2024-01-02
Expiration Date
2042-08-29
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Abstract
An improved alkaline pretreatment of biomass is provided that is a single-stage, two oxidant alkaline oxidative pretreatment process. The process uses a homogenous catalyst with at least two oxidants (Hydrogen peroxide and enhanced levels of oxygen) in an alkaline environment to catalytically pretreat lignocellulosic biomass in a single-stage oxidation reaction. The provided single-stage alkaline-oxidative pretreatment improves biomass pretreatment and increase enzymatic digestibility to improve the economic feasibility of production of lignocellulose derived sugars.
Core Innovation
The invention provides a single-stage, two oxidant alkaline oxidative pretreatment process for plant biomass, using a homogeneous metal-ligand catalyst and at least two oxidants—specifically hydrogen peroxide and enhanced levels of oxygen—in an alkaline environment. This process catalytically pretreats lignocellulosic biomass in a single-stage oxidation reaction, foregoing the conventional alkaline pre-extraction stage used in prior multi-stage processes. The approach seeks to improve the enzymatic digestibility of the pretreated biomass, thus boosting the recovery of sugars and lignin while reducing processing costs.
The technical problem addressed by the invention is the high recalcitrance and complex structure of plant cell walls, which impedes efficient fractionation and conversion of lignocellulosic biomass into fermentable sugars and other valuable bioproducts. Previous methods, particularly two-stage or single-oxidant processes, required higher chemical input such as large quantities of hydrogen peroxide and produced higher processing costs, limiting the economic viability of biofuel and biochemical production from plant materials.
By integrating pressurized oxygen as a co-oxidant with hydrogen peroxide in a single alkaline oxidative pretreatment step, the described process increases delignification and sugar yields, even at reduced hydrogen peroxide loadings. The single-stage configuration eliminates the need for separate alkaline pre-extraction, streamlining the procedure, lowering chemical and capital input, and enabling cost-effective biopolymer recovery (cellulose, hemicellulose, and lignin). The process is applicable across various plant biomasses and supports subsequent enzymatic hydrolysis, making lignocellulosic-to-biofuel conversion more practical at scale.
Claims Coverage
There are three primary independent inventive features identified in the claims.
Single-stage alkaline oxidative pretreatment with two oxidants and a metal-ligand complex
A method of pretreating plant biomass that catalytically treats the plant biomass in a single-stage alkaline oxidative pretreatment process. This process includes: - Providing a metal-ligand complex - Providing a base - Adding at least two oxidants to the alkaline oxidative pretreatment process to produce catalytically pretreated plant biomass The method is characterized specifically by not including an alkaline pre-extraction step prior to the alkaline oxidative pretreatment.
Cost reduction in homogeneous catalytic reaction using two oxidants
A method of reducing cost in a homogeneous catalytic reaction that involves: - Catalytically pretreating plant biomass with a metal-ligand complex and at least two oxidants present in a single-stage alkaline oxidative pretreatment process - Producing catalytically pretreated plant biomass - Hydrolyzing the catalytically pretreated biomass to produce hydrolyzed catalytically pretreated biomass for use as a biofuel Notably, the method does not include an alkaline pretreatment step prior to the alkaline oxidative pretreatment step. The use of two oxidants enables reductions in chemical input and minimum fuel selling price (e.g., by about 40% relative to using only hydrogen peroxide).
Use of pressurized oxygen as an oxidant in a single-stage oxidative pretreatment
A method of pretreating plant biomass in which the process includes: - Catalytically pretreating the plant biomass in a single-stage alkaline oxidative pretreatment process - Providing a metal-ligand complex - Adding at least two oxidants to the process, where one of the oxidants includes pressurized oxygen at least 100 psi The process may further include hydrogen peroxide as a co-oxidant, with both oxidants present simultaneously during pretreatment.
The inventive features collectively cover a single-stage alkaline oxidative pretreatment utilizing a metal-ligand complex and two oxidants (including pressurized oxygen), eliminating pre-extraction steps, reducing costs, and enabling improved biomass conversion.
Stated Advantages
The process reduces chemical input, particularly costly hydrogen peroxide, by using oxygen as a co-oxidant in combination with a metal-ligand catalyst.
Elimination of the alkaline pre-extraction stage streamlines process steps, simplifies biomass handling, and decreases both capital and operating costs.
Technoeconomic analysis indicates a reduction in minimum fuel selling price (MFSP) by about 30–40% compared to prior two-stage or single-oxidant processes.
The single-stage/two-oxidant process maintains or enhances sugar yields and lignin solubilization, resulting in higher or equivalent biopolymer recovery.
Reduction in catalyst (metal and ligand) and base usage lowers toxicity risk for downstream fermentation and decreases environmental and material costs.
Lignin isolated from the process maintains high hydroxyl content and remains suitable for downstream valorization into polyurethanes and aromatic monomers.
Use of pressurized oxygen as a co-oxidant with low hydrogen peroxide loading achieves high delignification and sugar yields comparable to two-stage processes.
Option for recovery and reuse of the metal-ligand catalyst to further decrease toxicity and process cost.
Documented Applications
Pretreatment of plant biomass—including hardwoods, grasses, and woody and non-woody materials—for improved conversion to fermentable sugars for biofuel production.
Production of hydrolyzed biomass for use as a biofuel following enzymatic hydrolysis.
Recovery of high-quality lignin suitable for conversion into aromatic monomers (such as vanillin, syringaldehyde, p-hydroxybenzoic acid, vanillic acid, syringic acid) and formulation of lignin-based polyurethanes.
Production of aliphatic acids (including formic acid, oxalic acid, acetic acid, lactic acid, succinic acid, azaleic acid) for use as food additives, polymer precursors, and fine chemicals.
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