Unveiling the Role and Mechanisms of Ceramic Fiber Filters in Flue Gas Desulfurization: A Review
摘要
Sulfur emissions from fossil-fuel combustion and industrial flue gas remain a persistent challenge because sulfur dioxide (SO2), sulfur trioxide (SO3), and sulfuric acid mist contribute to sulfate aerosol formation, corrosion, acid deposition, and adverse health impacts. Although flue gas desulfurization (FGD) is the dominant technology for large-scale SO2 control, ceramic fiber filters (CFFs) and catalytic ceramic fiber filters (CCFFs) are increasingly considered as compact platforms for integrating high-temperature particulate filtration with reactive gas treatment. A central challenge, however, is that sulfur loading and sulfur speciation are often substantially modified by upstream FGD units or alkaline sorbent injection before the gas reaches the filter. As a result, the intrinsic contribution of CFF/CCFF materials to sulfur mitigation is difficult to isolate, and reported removal efficiencies cannot be directly compared without considering the complete flue-gas treatment train. This review critically examines sulfur sources, transformations, and environmental impacts, followed by a focused assessment of CFF/CCFF materials, fabrication routes, catalytic configurations, and sulfur-removal mechanisms. Particular attention is given to distinguishing non-catalytic filtration, catalyst-assisted gas treatment, and sorbent-assisted SO2 capture governed by alkaline sorbents, cake-layer chemistry, operating temperature, particle size, and gas residence time. The available literature shows that CFF/CCFF systems provide a promising high-temperature platform for multi-pollutant control, but sulfur-specific demonstrations remain limited and strongly dependent on upstream process conditions. Future studies should therefore prioritize mechanism-resolved evaluation, standardized reporting of sulfur speciation and sorbent-to-sulfur ratios, long-term stability testing, regeneration behavior, and end-of-life management under realistic flue-gas matrices.
Graphical Abstract