Tungsten Catalyst Recovery from Ash via Acid Leaching
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Solution Overview
Problem
Existing processes for producing ethylene glycol and propylene glycol from carbohydrates using tungsten compounds as co-catalysts face challenges in recovering and regenerating tungsten compounds from ash, which often contain inorganic contaminants like sodium, calcium, and magnesium, leading to reduced catalytic efficiency and reactor contamination.
Innovation Solution
A process involving the treatment of ash with an inorganic acid of pH below 2, followed by separation, washing, and solubilization in an alkylene glycol composition with a controlled molar ratio of alkali hydroxide to tungstic acid, effectively recovering and regenerating tungsten compounds suitable for reuse as co-catalysts, while removing inorganic contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If ash is directly reused as catalyst without treatment, then tungsten compound recovery is achieved, but inorganic contaminants (sodium, calcium, magnesium) remain causing reduced catalytic efficiency and reactor contamination
Solution Approach 1:
The patent extracts harmful inorganic contaminants (sodium, calcium, magnesium) from the ash through acid treatment and filtration, separating them from the useful tungsten compound. The acid leaching process selectively dissolves alkali and alkaline earth metal contaminants while leaving tungsten compounds in the solid residue, which is then filtered out and reused as catalyst.
Solution Approach 2:
The patent changes the chemical environment by treating ash with acid (pH adjustment), which transforms the solubility characteristics of different components. The acid treatment converts insoluble inorganic contaminants into soluble forms that can be washed away, while tungsten compounds remain insoluble and recoverable.
2Reliability
If ash is treated with acid and washed to remove contaminants, then catalytic efficiency is maintained, but additional processing steps and time are required
Solution Approach 1:
The acid treatment process is designed to be self-limiting, where the acid naturally reacts with and removes contaminants until the ash is sufficiently purified. The process uses readily available acids and standard filtration equipment, making the regeneration process as efficient and automatic as possible without requiring complex additional steps.
3Reliability
If tungsten compound is continuously added to maintain concentration, then catalytic performance is maintained, but operational cost increases
Solution Approach 1:
Instead of discarding the spent tungsten-containing ash, the patent recovers and regenerates the tungsten compound by removing inorganic contaminants. The regenerated ash is then reused as catalyst, creating a closed-loop system that eliminates the need for continuous fresh tungsten compound addition and reduces operational costs.
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 process efficiently recovers and regenerates tungsten compounds, maintaining their catalytic activity and reducing inorganic contaminant buildup, thereby enhancing the long-term sustainability and efficiency of the carbohydrate hydrogenolysis reaction.
Implementation Method 1
contacting the ash with an inorganic acid having a pH of below 2
Implementation Method 2
washing the solid fraction obtained by step b. with an aqueous liquid
Implementation Method 3
solubilising the washed solids obtained by step c. in an alkylene glycol composition
Data Source
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AI summary
A process for recovering and regenerating a tungsten compound suitable as co-catalyst in converting carbohydrates with hydrogen into alkylene glycols and polyols, from ash comprising one or more tungsten-oxygen components (e.g. comprising a tungstate and/or tungstic acid). Such ash is obtainable from burning a liquid mixture comprising alkylene glycols and/or polyols and sodium tungstate and/or tungstic acid.