Glycol Production Buffer Segmentation for pH Control
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Solution Overview
Problem
Current methods for converting saccharides to glycols are sensitive to pH, leading to uncontrollable decreases in pH due to organic acid formation, resulting in tungstate precipitation and contamination of product streams, which increases production costs and requires additional processing to remove acids.
Innovation Solution
A process using a catalyst system with tungsten, molybdenum, and transition metals, in conjunction with a buffer system comprising heavy organic acids like ascorbic, benzoic, or lactic acid, which separates with the hydrocarbon heavies stream, preventing contamination of the glycol product stream and maintaining pH control within a desired range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If acids are added to buffer the reaction system to control pH, then pH stability is improved, but product stream contamination increases and additional processing is required
Solution Approach 1:
The patent segments the buffer system into two functional parts: a volatile acid component (acetic acid) that remains in the aqueous phase and provides pH buffering, and a heavy organic acid component (decanoic acid or undecanoic acid) that partitions into the hydrocarbon heavies phase. This segmentation allows the buffering function to be separated from the contamination problem, as the heavy acid is continuously removed with the hydrocarbon stream while the volatile acid maintains pH stability in the glycol product stream.
Solution Approach 2:
The heavy organic acid (decanoic acid or undecanoic acid) acts as an intermediary substance that mediates between the pH buffering requirement and the product purity requirement. It provides buffering capacity in the reactor while selectively partitioning into the hydrocarbon heavies phase during separation, thereby protecting the glycol product stream from acid contamination. The intermediary enables the system to achieve both pH stability and product purity simultaneously.
2Stability of the object's composition
If acids are continuously added to maintain buffering effect, then pH control is improved, but production cost increases
Solution Approach 1:
The patent implements a discarding and recovering strategy where the heavy organic acid buffer component is continuously discarded with the hydrocarbon heavies stream that is separated from the reactor product. By removing the contaminated heavy acid along with the hydrocarbon byproducts, the system prevents acid accumulation and maintains buffering efficiency without requiring continuous fresh acid addition. The volatile acid component is recovered in the glycol product stream, minimizing overall acid consumption and waste.
3Device complexity
If pH is not controlled, then process simplicity is maintained, but tungstate precipitation occurs and catalyst performance deteriorates
Solution Approach 1:
The buffer system operates on a self-service principle where the heavy organic acid automatically partitions into the hydrocarbon heavies phase during product separation, providing continuous pH control without external intervention. The system self-regulates by utilizing the natural phase separation behavior to remove excess acid and maintain optimal pH levels, eliminating the need for complex pH monitoring and adjustment mechanisms while ensuring catalyst performance stability.
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 approach effectively stabilizes pH, reduces tungstate deposition, and minimizes contamination of the glycol product stream, making the process more economically and environmentally friendly by recycling buffer components within the hydrocarbon heavies stream.
Implementation Method 1
a buffer system comprising a heavy organic acid for controlling the pH within the reactor
Implementation Method 2
contacting a saccharide-containing feedstock with a catalyst system comprising at least two active catalytic components
Implementation Method 3
as a second active catalyst component, one or more materials selected from transition metals from Groups 8, 9 or 10 or compounds thereof, with catalytic hydrogenation capabilities
Implementation Method 4
the heavy organic acid is an acid that remains in the liquid phase when water and C 2 -C 4 glycols are boiled off the reactor product stream
Implementation Method 5
recycling the hydrocarbon heavies stream at least partially back to the reactor
Data Source
AI summary
A process for the production of glycols is provided, the process comprising the steps of: (i) contacting a saccharide-containing feedstock with a catalyst system in a reactor in the presence of a reaction medium, a buffer system for controlling the pH within the reactor, and hydrogen; (ii) withdrawing a reactor product stream from the reactor; (iii) separating the reactor product stream into at least a glycol product stream and a hydrocarbon heavies stream; and (iv) recycling the hydrocarbon heavies stream at least partially back to the reactor; wherein components of the buffer system withdrawn from the reactor in the reactor product stream separate with the heavies stream and are recycled therewith.