钨对高钒燃气脱硝催化剂的改性及SCR反应历程研究

RESEARCH ON MODIFICATION OF TUNGSTEN TO HIGH VANADIUM DENITRATION CATALYST OF GAS TURBINE AND SCR REACTION PROCESS

针对燃气工况特点,以高钒SCR脱硝催化剂为研究对象,采用共浸渍法添加钨进行改性,考察了V_2O_5-WO_3/Ti O_2催化剂的SCR脱硝活性,表征了WO_3掺杂对V_2O_5氧化还原能力和酸性位的影响,并研究了该类型催化剂的SCR反应历程。结果表明:对于高钒脱硝催化剂,WO_3掺杂可以显著拓宽催化剂在280～440℃内的活性区间,但无法大幅提高催化剂的最高脱硝效率。活性温度区间得以拓宽的主要原因是WO_3掺杂后与V_2O_5发生强相互作用,在TiO_2表面形成V—O—W物种并提高V^(5+)物种比例,从而增加表面Br■nsted酸和Lewis酸位。在SCR脱硝反应中,催化剂表面酸性位对NH_3的吸附和活化是反应决速步骤,其后与气相NO反应,由气相中O_2补缺催化剂活化NH_3过程中消耗的晶格氧或—OH氧。

According to the characteristics of gas turbine working conditions, the high vanadium SCR denitration catalyst was used as the research object, the addition of tungsten was modified by co-impregnation method, the SCR denitration activity of V2O5-WO3/TiO2 catalyst was investigated, the effect of WO3 doping on V2O5 redox ability and acid site was characterized, and the SCR reaction process of this catalyst was researched.The results showed that in regard to high vanadium denitration catalysts, WO3 doping could significantly broaden the activity range of the catalyst from 280 ℃ to 440 ℃, but it couldn′t improve the maximum denitrification activity of the catalyst by a wide margin.The main reason for the broadening of the active temperature range was that the strong interaction with V 2O5 after WO3 doping formed V-O-W species on the surface of TiO2 and increased the proportion of V 5+ species, thereby increasing the surface BrΦnsted and Lewis acid sites.In the SCR denitration reaction, the ability of the acid sites to adsorb and activate NH3 on the surface of the catalyst was a reaction-determining step, and then reacted with the gas phase NO, and the O2 in the gas phase would fill the lattice oxygen or -OH oxygen of catalyst consumed in the process of activating NH3.