商用选择性催化还原催化剂SO_2氧化率控制研究进展

Research progress on the control of SO_2 oxidation by commercial SCR catalyst

选择性催化还原(SCR)法作为目前最成熟的氮氧化物(NO_x)控制技术被广泛地应用于燃煤电站等行业的NO_x排放控制过程,其核心是催化剂。商用SCR催化剂一般是以V_2O_5为活性组分、WO_3(或MoO_3)为催化助剂、TiO_2为载体的V_2O_5-WO_3(MoO_3)/TiO_2催化剂。该催化剂在催化NO_x还原的同时也会催化SO_2的氧化,生成的SO_3会给脱硝工程带来一系列的不利影响。基于此,本文首先介绍了钒钛催化剂催化氧化SO_2的反应机理及其研究进展,随后综述了影响SO_2氧化率的主要因素,主要包括催化剂中V_2O_5含量、催化助剂、飞灰、壁厚及烟气成分、反应温度等,并详细地分析了各因素对SO_2氧化率的影响特性。在此基础上,综述了控制SCR催化剂SO_2氧化率的方法。最后指出SO_2氧化率控制技术的发展对低SO_2氧化率脱硝催化剂的开发、失活催化剂的再生以及废弃催化剂的回用等均有着重要意义,是未来研究和开发的重点方向。

As the best nitrogen oxide （NOx） control technology, selective catalytic reduction （SCR） has been widely used in NOx emission control. The core of this technology is the catalyst. Typically, commercial V2O5-WO3 （MoO3）/TiO2 SCR catalyst consists of V2O5 as the active component, WO3 or MoO3 as the promotor, and TiO2 as the cartier. During the catalytic reduction of NOx, however, the oxidation of SO2 is catalyzed as well and the generated SO3 have significant negative effects on the denitrification process. In this review, the mechanism and research progress of SO2 oxidation were introduced at first. Then the main influence factors of the SO2 oxidation rate were reviewed and analyzed in detail, including V2O5 content, catalytic promoters, fly ash, catalyst wall thickness, flue gas composition and reaction temperature. On this basis, methods for controlling the SO2 oxidation rate over SCR catalyst were summarized. Overall, the SO2 oxidation rate control technology has made significant contributions to the development of low SO2 oxidation rate catalysts, regeneration of deactivated catalysts as well as recycling of disabled catalysts, and therefore deserves further research and development.