Inhibition effect of Ni/Fe/Co additives on sulfur-emission behavior during coal gas desulfurization over ZnO/MCM-41 at high temperatures and the regeneration behavior of modified sorbents
High temperature desulfurization of coal gas is one of the key steps for clean and efficient utilization of coal resources.Previous studies had found that MCM-41 supported ZnO sorbents(ZnO/MCM-41)exhibit outstanding hot-coal-gas desulfurization performance.However,there was COS formation(sulfur-release)during desulfurization process.Although the strategy of introducing additives into ZnO/MCM-41 for modifying sulfur-release behavior had been proposed,there was still a lack of research on the matching characteristics between additives and sorbents and the regeneration behavior of modified sorbents.The work showed that the doping of 1％—5％Ni/Fe/Co into ZnO/MCM-41 could effectively inhibit the release of COS by decreasing the corresponding COS-release amount of 99.4％—99.9％,73.1％—93.4％,and 69.0％—98.4％,respectively.The decrease is mainly attributed to the catalytic effect of additives on the hydrogenolysis of COS.Ni and Fe in modified sorbents exist in the form of Ni2+and Fe3+,respectively,while Co coexists in the form of Co2+and Co3+.For the optimized Ni-doping sorbent(3％),the regeneration temperature should not be lower than 600℃ because low-temperature regeneration leads to the presence of ZnS in regenerated sorbents.The optimized sorbent could maintain high sulfur capacity(91.5％of that for fresh sorbents)and low COS-release amount(4.8×10-2g COS/100g sorbents)after four desulfurization-regeneration cycles.The slight decrease in the ability of desulfurization and inhibiting sulfur-release is ascribed to the loss of a small fraction of active components and additives.The research could provide theoretical guidance for the preparation of high-performance sorbents.
hot coal gaszinc oxide sorbentcarbonyl sulfidecatalysisregenerationstability
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