Cellulose Hydrolysis Acid Recovery via Single-Phase Solvent Extraction
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Solution Overview
Problem
Current methods for processing cellulose-comprising materials with strong mineral acids to produce water-soluble carbohydrates face challenges in achieving high yield of acid recovery and high yield of soluble carbohydrates production, particularly due to issues with solvent selection and chemical stability, leading to economic inefficiencies and product degradation.
Innovation Solution
A method involving contacting cellulose-comprising input materials with an aqueous hydrolyzing solution containing at least 35% mineral acid, followed by extraction with a solvent S1 that forms a single phase with sulfuric acid, and subsequent fractionation to separate and reuse the acid and solvent, optimizing the process to prioritize acid recovery while minimizing carbohydrate loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If organic solvents are used to extract acid from hydrolysate, then acid recovery yield is improved, but chemical stability of the solvent deteriorates due to catalysis of condensation, dehydration or esterification reactions by strong acids
Solution Approach 1:
The patent changes the concentration parameter of the acid solution, using at least 35% wt. mineral acid which forms a single phase with the solvent. This high concentration prevents solvent degradation by eliminating the water-mediated hydrolysis pathway while still allowing effective acid extraction and recovery.
Solution Approach 2:
The patent utilizes phase behavior by selecting a solvent that forms a single phase with concentrated sulfuric acid at 25°C. This phase transition characteristic enables the system to maintain chemical stability while allowing for subsequent separation and recovery of the acid from the solvent mixture.
2Quantity of substance
If conventional extraction solvents are used, then acid separation is achieved, but carbohydrate degradation increases due to solvent instability in acidic conditions
Solution Approach 1:
The patent changes the acid concentration parameter to at least 35% wt., which fundamentally alters the chemical environment. This high acid concentration creates a single-phase system with the solvent that is chemically stable, preventing carbohydrate degradation while maintaining effective acid separation capability.
Solution Approach 2:
The patent introduces a specific solvent as an intermediary that mediates between the acid and carbohydrate components. This solvent selectively extracts acid from the hydrolysate while remaining chemically stable in the acidic environment, thereby protecting the carbohydrates from degradation that would occur with conventional solvents.
3Ease of manufacture
If acid is recovered from hydrolysate, then process economics are improved, but acid concentration decreases requiring reconcentration
Solution Approach 1:
The patent exploits phase behavior and solubility characteristics to recover acid in a concentrated form. By using a solvent that forms a single phase with at least 35% wt. sulfuric acid, the system enables direct separation and reuse of concentrated acid without requiring energy-intensive reconcentration steps, thereby improving process economics.
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 achieves high yield of acid recovery and production of water-soluble carbohydrates, reducing costs associated with acid reconcentration and minimizing carbohydrate degradation, thereby enhancing process economics and product yield.
Implementation Method 1
Inorganic acids, such as H3PO4 and H2SO4, as a result of their high proton activity, can catalyse both decrystallisation of cellulose and the hydrolysis of hemicellulose and cellulose to mono-, di- and oligosaccharides.
Implementation Method 2
Organic solvents with suitable solvent characteristics can be used to extract acid from a hydrolysate.
Implementation Method 3
S1 forms a single phase when mixed with an identical weight of 70% sulfuric acid aqueous solution at 25° C.
Data Source
AI summary
The present invention provides a method comprising: (i) contacting a cellulose-comprising input material with an aqueous hydrolyzing solution comprising at least 35% wt. of at least one mineral acid to form a hydrolyzate comprising a mixture of water-soluble carbohydrates and optionally a solid fraction; (ii) contacting said hydrolyzate with an extractant comprising a first solvent S1, to form a first (preferably solid) residue (preferably comprising precipitated carbohydrates, e.g. mono-, di- and/or oligo-saccharides) and an acid-comprising extract; (iii) separating said acid-comprising extract from said first residue; (iv) modifying said acid-comprising extract to form a second (preferably liquid) residue (preferably comprising dissolved carbohydrates) and an acid-comprising modified extract; (v) fractionating said modified extract into an S1-enriched fraction and an acid-enriched fraction; (vi) reusing said SI-enriched fraction to form said extractant; and (vii) reusing said acid-enriched fraction to form said aqueous hydrolyzing solution; wherein (a) at least 10% wt. of the cellulose is hydrolyzed and said mixture of water-soluble carbohydrates comprises monosaccharides, disaccharides and/or oligosaccharides; (b) SI forms a single phase when mixed with an identical weight of 70% sulfuric acid aqueous solution at 25° C.; (c) S1 comprises at least 65% wt. of said extractant; and (d) said acid-comprising extract comprises at least 60% wt. of the acid and at least 5% wt. of the carbohydrates in said hydrolyzate.