Doped Cerium Oxide Sorbent for Rapid H2S Desulfurization
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Solution Overview
Problem
Current desulfurization technologies face challenges in achieving high efficiency and rapid regeneration of sorbents at high temperatures, leading to long regeneration times, structural changes, and the need for multiple units, with existing sorbents like lanthanide oxides requiring high regeneration temperatures and experiencing reduced utilization due to the formation of oxy-sulfates and oxy-sulfides.
Innovation Solution
A doped cerium oxide sorbent is developed, allowing for efficient and regenerable removal of H2S at temperatures ranging from 500° C to 1000° C, with a method involving passing fuel gas through the sorbent at high space velocities to adsorb sulfur compounds on the surface and regenerating the sorbent by desorbing them, maintaining structural integrity and sulfur capacity over multiple cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lanthanide oxide sorbents are used for desulfurization, then sulfur removal capacity is improved, but regeneration time increases and structural stability deteriorates due to formation of oxy-sulfates and oxy-sulfides
Solution Approach 1:
The patent changes the chemical composition parameter of the sorbent by doping cerium oxide with specific metals (Cu, Mn, Fe, Co, Ni, Zn) to alter its regeneration behavior. This compositional modification enables the sorbent to maintain high sulfur capacity while achieving rapid regeneration without forming stable oxy-sulfate structures that slow down the regeneration process.
Solution Approach 2:
The patent creates composite sorbent materials by combining cerium oxide with dopant metals (Cu, Mn, Fe, Co, Ni, Zn). These composite structures synergistically combine the high sulfur capacity of cerium oxide with the rapid regeneration properties of the dopant metals, preventing the formation of stable oxy-sulfates while maintaining sulfidation capacity.
2Productivity
If high regeneration temperatures are applied, then regeneration speed is improved, but sorbent structural integrity deteriorates and sulfur capacity is lost
Solution Approach 1:
The patent modifies the thermal stability parameter of the sorbent through metal doping, which changes the decomposition temperature and phase transition behavior of the oxide structure. The dopant metals create more stable crystal structures that resist degradation at high temperatures, enabling rapid regeneration without structural collapse or permanent sulfur capacity loss.
Solution Approach 2:
The composite structure of doped cerium oxide combines the thermal stability of cerium oxide with the high-temperature resistance of dopant metals. This composite material maintains structural integrity during rapid high-temperature regeneration cycles, preventing sintering and phase transformations that would permanently reduce sulfur capacity.
3Reliability
If multiple sorbent units are used to maintain continuous operation, then sulfur removal reliability is improved, but device complexity and cost increase
Solution Approach 1:
The patent implements periodic action by enabling rapid regeneration of the sorbent within the same reactor vessel. The sorbent alternates between sulfidation (sulfur removal) and regeneration modes in rapid succession, allowing continuous operation with a single unit rather than requiring multiple parallel reactors. The fast regeneration cycle (minutes rather than hours) enables this single-vessel periodic operation to maintain continuous sulfur removal capability.
4Quantity of substance
If sorbent utilization is increased through bulk sulfidation, then sulfur capacity is improved, but regeneration difficulty increases and sulfur recovery becomes complicated
Solution Approach 1:
The patent changes the sulfidation depth parameter by controlling reaction conditions (temperature, time, H2S partial pressure) to achieve optimal bulk sulfidation without complete conversion. The doped cerium oxide sorbent maintains high sulfur capacity through partial bulk sulfidation while the dopant metals prevent formation of overly stable sulfide phases that are difficult to regenerate, enabling easier sulfur recovery compared to fully sulfided sorbents.
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 doped cerium oxide sorbent enables rapid desulfurization and regeneration, maintaining sulfur capacity and structural stability, allowing for efficient collection of H2S in the regeneration offgas without further treatment, suitable for a wide range of temperatures and sorbent materials, thus addressing the limitations of existing technologies.
Implementation Method 1
passing fuel gas through the sorbent at high space velocities to adsorb sulfur compounds on the surface
Implementation Method 2
regenerating the sorbent by desorbing sulfur compounds from the surface
Implementation Method 3
MyO+H2S+H2 (or CO)→MyS+H2O (or CO2)
Data Source
AI summary
Disclosed is a doped cerium oxide sorbent that can effectively and regenerably remove H2S in the temperature range of about 500° C. to about 1000° C. Regenerable sorbents (e.g., ZnO, La2O3, CeO2) and methods of using them are disclosed that allow cyclic desulfurization from about 300-500° C., 350-450° C., and at about 400° C. In one embodiment, the present invention relates to a method of desulfurizing fuel gas comprising passing the fuel gas through the sorbent at a space velocity wherein the sulfur compounds are adsorbed substantially on the surface of the sorbent; and regenerating the sorbent by passing a regenerating gas through the sorbent, wherein substantially all of the sulfur compounds are desorbed from the sorbent surface. In a further embodiment, the method of desulfurizing fuel gas further comprises repeating the aforementioned steps while the fuel processor is in operation. In another embodiment, the step of passing the fuel gas may be preceded by reducing the sorbent by passing a reducing gas through the sorbent. In another embodiment, the sorbent may be fully sulfided, i.e., sulfided on its surface and bulk (internally).