球磨制备低钒基催化剂的NH3-SCR脱硝性能

采用球磨混合方法，将催化剂以m（Cu/SAPO-34）:m（VW/TiO₂）为1:1的比例制得干混样品SAPO-Ti。利用固定床实验台架研究了混合催化剂的NH₃-SCR脱硝性能及其抗硫性能。采用 XRD、BET、SEM、H₂-TPR、NH₃-TPD和in-situ DRIFT对材料进行表征，结果显示，球磨混合样品SAPO-Ti同时具有2种催化剂的晶体结构，且酸量增加，中温活性提高。表面形貌研究表明，VW/TiO₂催化剂覆盖在Cu/SAPO-34催化剂表面，对Cu/SAPO-34催化剂起到保护作用；原位红外结果显示，Cu/SAPO-34催化剂硫中毒失活主要是在Cu活性位上形成硫酸盐物种，导致活性位减少，脱硝效率下降，而SAPO-Ti表面形成硫酸盐的数量减少，抗硫性能提高，主要是由于表面VW/TiO₂催化剂具有良好的抗硫性，保护内部Cu2+活性位，以保持高效中温脱硝性能。

NH3-SCR PERFORMANCE OF LOW VANADIUM-BASED CATALYST PREPARED BY BALL MILLING

The modified sample SAPO-Ti was prepared by ball-milling method with Cu/SAPO-34 catalyst and VW/TiO₂ catalyst with a mass ratio of 1:1. The performance and sulfur resistance of mixed catalyst in NH₃-SCR process was studied by a fixed bed test bench. The physical and chemical properties of the catalysts were characterized by X-ray diffraction analysis (XRD), N₂ adsorption-desorption (BET), scanning electron microscope (SEM), hydrogen temperature programmed reduction (H₂-TPR), NH₃-TPD and in-situ DRIFT. The results showed that the ball-milled mixed sample SAPO-Ti remained the crystal structure of the two catalysts with high acid content and moderate-temperature activity. Surface morphology showed that the VW/TiO₂ catalyst covered on the surface of the Cu/SAPO-34 catalyst and protected Cu/SAPO-34 catalyst framework; the sulfur poisoning was observed by in-situ DRIFT, and the results showed that sulfur poisoning deactivation of Cu/SAPO-34 mainly formed sulfate species on the active site of Cu, which reduced the active sites and then desulfurixation efficiency. However, the accumulation of sulfur-contained species formed on the surface of SAPO-Ti catalyst obviously was reduced and the sulfur resistance was improved, because VW/TiO₂ in the outer surface with high sulfur resistance protected the internal Cu2+ active sites to maintain the high efficiency of medium temperature demitration and kept Cu/SAPO-34 catalyst from poisoning.