Pulp Cooking Additives for High-Brightness Delignification
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Solution Overview
Problem
The pulp and papermaking industry faces challenges in efficiently separating wood fiber components, particularly lignin, which results in low brightness and high chemical consumption during bleaching, leading to environmental pollution and high production costs.
Innovation Solution
A method involving the addition of a lignin precursor small-molecule organic compound and a short-chain polyol during high-temperature cooking to form a nucleophilic combination that reduces lignin molecular weight and blocks condensation reactions, thereby improving lignin removal and obtaining high-brightness pulp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional pulping processes are used to remove lignin, then lignin removal rate is improved, but pulp brightness remains low (20-30% ISO) and requires extensive bleaching
Solution Approach 1:
The patent introduces a small-molecule phenolic organic compound as an intermediary substance that preferentially reacts with active sites of lignin during cooking. This intermediary compound acts as a mediator between the cooking process and lignin, modifying lignin's chemical structure to reduce its condensation tendency and improve its removal efficiency, thereby achieving both high lignin removal rate and high pulp brightness simultaneously
Solution Approach 2:
The patent changes the chemical parameters of the cooking process by adding small-molecule phenolic organic compounds with specific molecular weights and functional groups. This parameter change modifies the reaction characteristics between cooking chemicals and lignin, transforming lignin into a more removable form that achieves both high removal rate and high pulp brightness without extensive bleaching
2Manufacturing precision
If extensive bleaching is performed to improve pulp brightness, then pulp purity is improved, but chemical consumption increases and environmental pollution worsens
Solution Approach 1:
The patent performs preliminary action by adding small-molecule phenolic organic compounds during the cooking stage to pre-modify lignin structure and pre-remove some lignin before bleaching. This preliminary delignification reduces the lignin burden that would otherwise require extensive bleaching, thereby reducing chemical consumption and environmental pollution while still achieving high cellulose purity
Solution Approach 2:
The patent converts the harmful effect of lignin (which causes brown color and requires extensive bleaching) into a benefit by using small-molecule phenolic compounds to selectively react with and modify lignin during cooking. This transformation turns lignin from a problematic substance that needs heavy chemical treatment into a more readily removable substance, reducing overall chemical consumption and environmental impact
3Loss of substance
If small-molecule aldehyde organic compound and organic acid are used for lignin removal, then lignin removal rate is improved, but pulp brightness improvement is insufficient
Solution Approach 1:
The patent changes the key parameter of the additive from small-molecule aldehyde organic compounds to small-molecule phenolic organic compounds with specific functional groups. This parameter change fundamentally alters the chemical interaction mechanism with lignin, enabling preferential reaction with lignin active sites and achieving both high lignin removal rate and significant pulp brightness improvement that aldehyde compounds cannot achieve
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
The method achieves high-brightness pulp directly, reduces residual lignin and chemical use, and facilitates the recovery of high-activity lignin and hemicellulose, with a simpler process and lower environmental impact.
Implementation Method 1
the lignin precursor small-molecule and short-chain polyol form the nucleophilic combination to react with as many electrophilic active sites of a lignin intermediate as possible. After occupying these electrophilic sites of the lignin intermediate, the lignin intermediate loses its reactivity, thereby blocking a reaction between the electrophilic sites of the lignin intermediate and the nucleophilic sites of the lignin molecules per se, and then preventing condensation reaction between the lignin molecules
Implementation Method 2
subjecting a lignocellulose raw material to high-temperature treatment in the presence of a lignin precursor small-molecule organic compound, a short-chain polyol, and a cooking agent to obtain the pulp with relatively high brightness and the high-activity lignin
Data Source
AI summary
A method for preparing a pulp with relatively high brightness and a high-activity lignin is provided, belonging to the field of pulp and papermaking engineering. In the method, a lignin precursor and a polyol are added during the cooking of a raw material to obtain the pulp with relatively high brightness. In the method, the lignin precursor and the polyol form a nucleophilic combination (including active organic small molecules containing short chains and aromatic moieties) during delignification, which undergoes a saturated condensation reaction on a side chain position of the lignin.