Cobalt-Molybdenum Sulfide Catalyst Stability via Sulfur Recycling
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Solution Overview
Problem
Existing catalysts for converting synthesis gas to alcohols, particularly cobalt-molybdenum sulfide systems, lack guidance on maintaining long-term stability and optimal sulfur content, leading to reduced catalytic activity and selectivity over time.
Innovation Solution
A method involving a catalyst composition with a specific sulfur-to-cobalt molar ratio, supplemented with additional sulfur to maintain the cobalt and molybdenum in a sulfided state, and the use of sulfur-containing compounds to inhibit carbide formation, along with sulfur recycling and accelerated aging techniques to predict catalyst stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cobalt-molybdenum sulfide catalyst is used for syngas conversion, then initial catalytic activity is achieved, but long-term stability and selectivity deteriorate over time due to carbide formation and sulfur loss
Solution Approach 1:
The patent applies preliminary sulfidation treatment to the catalyst before use, establishing a sulfur-rich environment that prevents carbide formation during operation. This preparatory action ensures the catalyst maintains its sulfided state and prevents deactivation mechanisms from occurring
Solution Approach 2:
The patent implements continuous monitoring of catalyst performance parameters and adjusts operating conditions or sulfur supplementation based on observed changes. This feedback mechanism detects early signs of deactivation and allows corrective actions to maintain catalyst stability throughout operation
Solution Approach 3:
The patent modifies key operating parameters including temperature, pressure, and sulfur partial pressure to optimize catalyst stability. By carefully controlling these parameters, the catalyst operates in a regime that prevents carbide formation while maintaining high activity and selectivity for extended periods
2Manufacturing precision
If sulfur content is increased to maintain sulfided state, then catalytic selectivity is improved, but carbide formation risk increases when sulfur is depleted
Solution Approach 1:
The patent introduces sulfur-containing compounds as intermediary substances that continuously replenish sulfur on the catalyst surface. These sulfur donors act as a buffer, maintaining the sulfided state and preventing direct contact between cobalt and carbon that would lead to carbide formation
Solution Approach 2:
The patent creates a composite catalyst system combining cobalt-molybdenum sulfide with sulfur-containing promoters or supports. This composite structure ensures sustained sulfur availability while maintaining the active sulfided phases necessary for high selectivity, preventing carbide formation through the synergistic interaction of components
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 effectively maintains catalytic activity and selectivity for extended periods, preventing carbide formation and ensuring stable ethanol production, with the potential for sulfur recycling reducing costs and operational issues.
Implementation Method 1
cobalt-molybdenum sulfide catalyst materials and methods for stable alcohol production from syngas
Implementation Method 2
injecting additional sulfur, or a compound containing sulfur, into the reactor in an amount that is sufficient to maintain at least some of the cobalt in a sulfided state
Data Source
AI summary
The present invention provides methods and compositions for the chemical conversion of syngas to alcohols. The invention includes catalyst compositions, methods of making the catalysts, and methods of using the catalysts including techniques to maintain catalyst stability. Certain embodiments teach compositions for catalyzing the conversion of syngas into products comprising at least one C1-C4 alcohol, such as ethanol. These compositions generally include cobalt, molybdenum, and sulfur, and avoid metal carbides both initially and during reactor operation.