Abstract: Rapid industrialization has resulted in significant gaseous sulfur dioxide (SO2) pollutant emissions, which come from power plants, petrochemical industries, and metallurgical plants. This toxic, non-inflammable, and notorious pollutant poses a threat to ecosystems, contributes to acid rain formation, and leads to the corrosion of equipment and infrastructure. Catalytically reducing SO2 to elemental sulfur, which is a benign and valuable product, in a reducing atmosphere is a promising solution. It has gained considerable attention not only for the SO2 emission reduction, but also for the resource utilization of SO2 waste gas. In this study, iron doping perovskite materials (denoted as LaCo0.8Fe0.2O3) were synthesized by the citric acid induced sol-gel method followed by calcination at a certain temperature. The material was subjected to oxygen-free sulfurization (which is denoted as OFS-LaCo0.8Fe0.2O3) and oxygen free sulfurization under dielectric barrier discharge (DBD) plasma conditions (which was denoted as POFS-LaCo0.8Fe0.2O3). X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM) were used to analyze the structure and properties of the catalytic materials. The performance of sulfur production by DBD thermal-catalytic reduction of SO2 under CO, and combined CO and H2 reducing atmospheres was investigated, together with the by-products under different catalytic materials and varied reducing gas conditions. The XRD results showed that both OFS-LaCo0.8Fe0.2O3 and POFS-LaCo0.8Fe0.2O3 maintained the perovskite crystal form with a weaker decrease in peak intensity compared to LaCo0.8Fe0.2O3. After catalytic reaction with SO2, the XRD pattern exhibited other weak impurity peaks. With CO reduction, compared with DBD reduction alone, the combination of DBD plasma and the catalyst increased the SO2 conversion rate from 82.3% to 95.0% at 450℃. In addition, the SO2 conversion rate reached 99.8% under co-reduction with CO and H2 at 300℃. The H2-TPR results indicated that the reduction peak of LaCo0.8Fe0.2O3 showed better reducibility at lower temperatures compared to OFS-LaCo0.8Fe0.2O3, which may contribute to the increased SO2 conversion.

Key words: plasma, perovskite, catalytic reduction, sulfur production from sulfur dioxide, reducing atmosphere

摘要： 快速工业化进程导致毒性二氧化硫(SO2)大量排放，引发酸雨等严重生态问题。利用还原气氛将SO2催化还原为具有经济价值的硫磺，是一种变废为宝的有效途径。本研究通过溶胶-凝胶法合成了LaCo0.8Fe0.2O3钙钛矿材料，并对材料进行了无氧预硫化(OFS-LaCo0.8Fe0.2O3)和介质阻挡放电(Dielectric Barrier Discharge, DBD)等离子体条件下的无氧预硫化(POFS-LaCo0.8Fe0.2O3)处理，采用X射线衍射(XRD)、比表面积检测法(BET)和扫描电子显微镜(SEM)等分析手段研究了催化材料的结构和性质。同时，考察了CO和H2还原气氛下，DBD热催化还原SO2制备硫磺的性能。XRD结果表明，与LaCo0.8Fe0.2O3相比，OFS-LaCo0.8Fe0.2O3和POFS-LaCo0.8Fe0.2O3的钙钛矿衍射峰强度微弱降低，且催化反应后出现微弱的杂质峰。性能测试表明，相比无催化剂等离子体下CO还原体系，DBD与催化剂结合的方法可使450℃下SO2转化率从82.3%提升至95.0%。此外，CO和H2共还原条件下，300℃时SO2转化率已接近99.8%。H2-TPR结果表明，LaCo0.8Fe0.2O3的还原峰相比OFS-LaCo0.8Fe0.2O3具有低温易还原性，这可能是其实现高SO2转化率的原因。

关键词: 等离子体, 钙钛矿, 催化还原, 二氧化硫制硫磺, 还原气氛