Silver Tungstate Catalyst for Saccharide Conversion
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Solution Overview
Problem
Current catalyst systems for converting saccharide-containing feedstocks to glycols, such as monoethylene glycol and monopropylene glycol, are sensitive to contaminants like sulfur, leading to reduced product yields and selectivity issues.
Innovation Solution
A catalyst system comprising silver tungstate or silver phosphotungstate combined with transition metals from Groups 8, 9, or 10, which provides improved tolerance to contaminants and enhanced yields of MEG and MPG, with a weight ratio of silver and tungsten species to hydrogenation species ranging from 0.02:1 to 3000:1.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional catalyst systems (nickel-promoted tungsten carbide, tungstic acid, tungsten oxide, phosphotungstic acid, ammonium metatungstate) are used for converting saccharides to glycols, then the hydrogenolysis and hydrogenation reactions can proceed, but the catalyst systems show sensitivity to sulfur and other contaminants leading to reduced product yields and selectivity
Solution Approach 1:
The patent employs a composite catalyst system combining tungsten-based compounds (for hydrogenolysis via retro-aldol mechanism) with nickel-based compounds (for hydrogenation). This composite approach creates synergistic effects where the tungsten component handles the breakdown of saccharides while the nickel component facilitates hydrogenation, and together they exhibit enhanced tolerance to sulfur contaminants compared to either component alone, maintaining high MEG and MPG yields despite feedstock impurities
2Manufacturing precision
If conventional catalyst systems are used, then the conversion process can operate, but selectivity to MEG and MPG is reduced with increased by-product formation
Solution Approach 1:
The patent applies local quality by assigning specific functional roles to different catalyst components: tungsten compounds (particularly tungstic acid, tungsten oxide, phosphotungstic acid, or ammonium metatungstate) are optimized for the hydrogenolysis step with retro-aldol mechanism to generate specific intermediates, while nickel compounds are optimized for the subsequent hydrogenation step. This functional differentiation at the molecular level ensures high selectivity toward MEG and MPG while minimizing by-product formation from non-selective reactions
3Duration of action of stationary object
If sulfur-containing feedstocks are processed with conventional catalysts, then the conversion can proceed initially, but catalyst activity decreases over time leading to reduced yields
Solution Approach 1:
The patent converts the harmful effect of sulfur contaminants into a manageable condition by developing a dual-catalyst system with inherent sulfur tolerance. The tungsten-nickel composite catalyst maintains stable activity in sulfur-containing environments, allowing continuous processing of biomass feedstocks without frequent catalyst replacement or regeneration. This enables sustained high yields of MEG and MPG over extended operation periods despite the presence of sulfur and other impurities in the feedstock
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 catalyst system achieves higher yields of MEG and MPG with increased selectivity and resistance to feedstock contaminants, maintaining high performance even in the presence of sulfur and other impurities.
Implementation Method 1
a first catalytic species to perform the hydrogenolysis reaction, which is postulated to have a retro-aldol mechanism
Implementation Method 2
a second catalytic species for hydrogenation
Data Source
Figure 1
AI summary
The invention provides a catalyst system comprising: a) one or more catalytic species comprising silver and tungsten therein; and b) one or more catalytic species suitable for hydrogenation; and a process for the preparation of monoethylene glycol from starting material comprising one or more saccharides, by contacting said starting material with hydrogen in a reactor in the presence of a solvent and said catalyst system.