Abstract:

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.

Key words: hot coal gas, zinc oxide sorbent, carbonyl sulfide, catalysis, regeneration, stability

摘要：

高温煤气脱硫是煤炭清洁高效利用的关键步骤之一。前期研究发现，MCM-41负载ZnO高温煤气脱硫剂（ZnO/MCM-41）脱硫性能优良，但其脱硫过程中存在生成COS的放硫现象；尽管提出了引入助剂调变上述放硫行为的策略，但缺乏助剂与脱硫剂匹配特性及改性脱硫剂再生行为的研究。本研究表明，在ZnO/MCM-41中引入质量分数1%~5%助剂（Ni/Fe/Co），均可有效抑制COS释放（释放量分别降低99.4%~99.9%、73.1%~93.4%和69.0%~98.4%），这主要归因于助剂对COS氢解的催化作用；脱硫剂中镍、铁分别以Ni²⁺和Fe³⁺形式存在，而钴以Co²⁺和Co³⁺形式共存；对于性能最优的Ni掺杂（质量分数3%）脱硫剂，其再生温度应不低于600℃（低温再生仍存在部分ZnS）；且脱硫剂经四次循环再生实验后可维持高硫容（初次的91.5%）及低COS释放量（4.8×10^-2g 羰基硫/100g脱硫剂），轻微的性能下降可归因于活性组分及助剂的少部分损失。上述研究可为高性能脱硫剂构筑提供理论指导。

关键词: 热煤气, 氧化锌脱硫剂, 硫化碳, 催化, 再生, 稳定性