NH3-SCR PERFORMANCE OF LOW VANADIUM-BASED CATALYST PREPARED BY BALL MILLING
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摘要: 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。Abstract: 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.
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Key words:
- catalyst /
- SCR /
- ball milling modification /
- deactivation /
- sulfur resistance
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