Datang Nanjing Environmental Protection Technology Co.,Ltd.
Jiangsu JITRI-Topsoe Institute of Advanced CatalyticTechnology
Jiangsu JITRI-Topsoe Clean Energy R&D Co.,Ltd.
Instrumental Analysis Center,Inner Mongolia University of Science & Technology

选择性催化还原(SCR)是目前应用最广的烟气脱硝技术,其核心为SCR脱硝催化剂。燃煤烟气飞灰中由于As元素的存在会导致催化剂的中毒失活及使用寿命大幅下降,影响SCR系统稳定高效运行。为提升V-Mo/Ti催化剂的抗As中毒性能,制备了不同MoO3质量分数(3%和7%)的V-Mo/Ti催化剂。随后,采用模拟中毒法,制备了As中毒催化剂。通过XRF、ICP、XRD、N2-吸附脱附、H2-TPR、XPS、NH3-TPD和O2-TPD,考察了新鲜催化剂和As中毒后催化剂的理化性质。通过固定床微型反应评价装置,测试了各催化剂在230~410℃烟气温度区间内的脱硝效率和N2O生成量。结果显示,As会影响V-Mo/Ti催化剂的孔结构,降低催化剂的比表面积、孔容、还原性能、酸性性能和化学吸附氧含量,从而降低催化剂的脱硝活性,并促进副产物N2O的生成。增加MoO3含量,催化剂的孔结构得到改善,比表面积和孔容下降幅度降低,还原性能和表面酸量提升,催化剂的脱硝活性增加。较高的MoO3质量分数(7%)可以减轻As对催化剂的毒化作用。与V-Mo(3)/Ti-As催化剂相比,V-Mo(7)/Ti-As催化剂在230~410℃烟气温度区间内的脱硝效率更高,说明V-Mo(7)/Ti催化剂具备较强的抗As中毒性能。

Selective catalytic reduction (SCR) is currently the most widely used flue gas denitrification technology,with the core methodSCR denitrification catalyst. The presence of the As element in coal combustion fly ash can cause catalyst poisoning and a significantdecrease in service life,affecting the stable and efficient operation of the SCR system. V-Mo/Ti catalysts with different mass fractions ofMoO3 (3% and 7%) were prepared,in order to improve the As resistance of V-Mo/Ti catalyst. The As poisoned catalysts were alsoprepared by wet impregnation method. The physiochemical properties of the fresh and As-poisoned catalysts were characterized by XRF,ICP, XRD, N2-physisorption, H2-TPR, XPS, NH3-TPD, and O2-TPD. The NOx conversion and N2O concentration of the differentcatalysts in the temperature range 230−410 ℃ were tested via a micro fixed-bed reactor. The results show that As has negative influenceson the pore structure of the catalyst,and reduces the specific surface area,pore volume,reducibility,acidity,and the amount of Oα of thecatalyst. As a result,the catalytic activity of the catalyst declines and the generation of by-product N2O promotes. With the increase ofMoO3 content,the pore structure of catalyst is improved,the decrease in specific surface area and pore volume is reduced,the reductionperformance and surface acid content are increased,and the denitrification activity of catalyst is increased. High mass fraction of MoO3(7%) can reduce the poisoning effect of As on the V-Mo/Ti catalyst. The catalytic performance of V-Mo(7)/Ti-As catalyst is obviously higher than that of the V-Mo(3)/Ti-As catalyst. In the other word,the As resistance of V-Mo(7)/Ti catalyst is superior to that of the V-Mo(3)/Ti catalyst.

江苏省自然科学基金资助项目(BK20210001)

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