Low Molecular Weight Lignin Extraction via Alkaline Peroxide
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Solution Overview
Problem
Current biorefinery processes face challenges in selectively extracting high-purity, sulfur-free low-molecular weight lignin from lignocellulosic materials, which is essential for plastic and resin production due to the limitations of existing lignin separation methods, particularly the sulfur content in lignins obtained from traditional processes.
Innovation Solution
A method involving the use of an aqueous extraction solution with C1-4 alcohols at specific concentrations and pH levels to selectively produce low molecular weight lignin (NML) from lignocellulosic materials, allowing for its concentration through recycling and subsequent use in resin or plastic production, reducing sulfur content and molecular weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional kraft pulping or sulfite process is used to obtain lignin, then lignin can be obtained in sufficient quantity, but the lignin contains sulfur (thiol groups or sulfonates) which causes odor and limits chemical applications
Solution Approach 1:
The patent changes the chemical parameters of the extraction system by using alkaline peroxide treatment instead of traditional kraft or sulfite conditions. This involves using hydrogen peroxide as the oxidizing agent under alkaline conditions (pH 10-12), which fundamentally alters the extraction chemistry to avoid sulfur incorporation while maintaining effective lignin dissolution and enabling selective fractionation into low molecular weight and neutral lignin fractions
Solution Approach 2:
The patent applies selective extraction by separating lignin into different molecular weight fractions through controlled alkaline peroxide treatment. By optimizing parameters such as peroxide dosage, treatment time, and pH, the process selectively extracts low molecular weight lignin and neutral lignin while leaving high molecular weight condensed lignin in the residue, thereby obtaining sulfur-free lignin suitable for chemical applications
2Object-generated harmful factors
If alkaline extraction is used to obtain sulfur-free lignin, then sulfur content is reduced, but the molecular weight of extracted lignin is not controlled and high molecular weight fractions dominate
Solution Approach 1:
The patent employs parameter optimization including alkaline pH (10-12), controlled peroxide dosage (1-5% w/w relative to lignocellulose), and specific treatment temperatures (50-80°C) to control the degree of lignin depolymerization. These parameter changes enable selective generation of low molecular weight lignin fractions while minimizing formation of high molecular weight condensed lignin
Solution Approach 2:
The patent uses time-dependent periodic treatment where the alkaline peroxide extraction is performed for controlled durations (1-6 hours) followed by filtration and optional recycling of the extract. This periodic action allows controlled depolymerization and selective extraction of low molecular weight lignin before repolymerization can occur
3Quantity of substance
If alcohol concentration is increased to 100% in aqueous alkaline solution, then lignin extraction is enhanced, but sugar release approaches zero and extraction efficiency decreases
Solution Approach 1:
The patent optimizes the alcohol concentration parameter to the specific range of 70-95% v/v in the aqueous alkaline extraction solution. This parameter optimization balances lignin extraction efficiency with sugar co-extraction minimization, achieving effective lignin recovery while maintaining high productivity. The patent specifically identifies 80-90% alcohol concentration as the optimal range based on experimental data
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively increases the concentration of low molecular weight lignin, reduces the need for solvents and base consumption, and provides sulfur-free lignin suitable for high-purity plastic and resin production, enhancing the economic viability of biorefinery processes.
Implementation Method 1
The underlying chemical principle is alkaline hydrolysis, which breaks down both the connection between lignin and hemicellulose and the acetic acid-hemicellulose ester.
Implementation Method 2
a) lignocellulosic material with an aqueous extraction solution containing a C 1-4 alcohol, in particular ethanol or isopropanol, from 70% v/v to 95% v/v, in particular 75% v/v to 85% v/v, is treated at a pH of 12 to 14, obtaining an aqueous solution of low molecular weight lignin (NML)
Data Source
Figure 1~2
AI summary
Process for obtaining resin or synthetic material using lignocellulosic material by treating lignocellulosic material with an aqueous extraction solution with a content of a C1-4-alcohol of 70% v/v to 95% v/v at a pH of 12 to 14, where a first aqueous solution of low molecular weight lignin (LML) is obtained which is converted to resin or synthetic material; and a process for obtaining LML and a process for concentrating LML where the first aqueous solution of LML is used for treating further lignocellulosic material to obtain aqueous solutions in which the LML is enriched compared with the first aqueous solution.