铁基分子筛SCR反应组分沿催化剂轴向分布的数值模拟  

Numerical Simulation of Axial Species Distribution of SCR Reaction over Fe-Zeolite Catalyst

作　　者：吕志华 苏庆运[2,1,3] 佟德辉 张学敏 李宁 李凌志 Lyu Zhihua;Su Qingyun;Tong Dehui;Zhang Xuemin;Li Ning;Li Lingzhi(State Key Laboratory of Engine and Powertrain System,Weichai Power Company Limited,Weifang 261061,China;Institute of Internal Combustion Engine,Dalian University of Technology,Dalian 116024,China;Weichai Power Emission Solutions Incorporated,Weifang 261061,China)

机构地区：[1]潍柴动力股份有限公司内燃机与动力系统全国重点实验室,山东潍坊261061 [2]大连理工大学内燃机研究所,辽宁大连116024 [3]潍柴动力空气净化科技有限公司,山东潍坊261061

出　　处：《内燃机学报》2024年第3期245-252,共8页Transactions of Csice

基　　金：国家自然科学基金资助项目(51876028,51476021);中国博士后科学基金资助项目(2016M590651);天津大学内燃机燃烧学国家重点实验室开放基金资助项目(K2016-10);中央高校基本科研业务费专项资金资助项目(DUT15QY25).

摘　　要：建立铁基分子筛催化剂NH_(3)-SCR催化反应动力学模型,用来预测催化剂的NO_(x)还原性能和研究SCR反应组分的轴向分布,该模型包括NH_(3)吸附与脱附、NH_(3)氧化、NO氧化、NO_(x)还原及N_(2)O生成反应.结果表明:模型能较好地预测SCR反应中各组分浓度在催化剂轴向空间的变化规律;Fe基分子筛催化剂对物质的量n(NO_(2))/n(NO_(x))较为敏感,最佳n(NO_(2))/n(NO_(x))为0.5;受NH_(3)抑制效应影响,当温度低于300℃时SCR反应活性较低,但是当温度高于400℃时SCR反应活性较好.此外,发现Fe基分子筛催化剂SCR反应主要集中在催化剂的入口段和中间段,300℃、空速为60000 h^(-1)时在催化剂的前半段内可实现高达90%的NO_(x)转化率,催化剂出口段的利用率较低.最后,对模型的瞬态性能进行了考察,发现随着温度升高Fe基分子筛催化剂的瞬态响应可以得到改善.A kinetic model of NH_(3)-SCR catalytic reaction over Fe-zeolite catalyst was established to predict the NO_(x)reduction performance of the catalyst and to investigate the axial species distribution during SCR reaction.The model is composed of NH_(3)adsorption and desorption,NH_(3)oxidation,NO oxidation,NO_(x)reduction and N_(2)O formation reactions.The results show that the model can predict the variation of species concentration in axial space.It was found that the Fe-zeolite catalyst is sensitive to molar ratio of n(NO_(2))/n(NO_(x)),and the optimal n(NO_(2))/n(NO_(x))is 0.5.Because of the NH_(3)inhibition effect,the SCR activity is low at the temperature lower than 300℃,while high at the temperature above 400℃.In addition,the SCR reaction of Fe-zeolite occurs mainly in the inlet and middle segments of the catalyst.At the temperature of 300℃and the space velocity of 60000 h^(-1),up to 90%NO_(x)conversion could be achieved in the front half of the catalyst.The utilization rate of the catalyst is low at the outlet segment of the catalyst.Furthermore,the transient performance of the model was investigated,and it is found that the transient response of Fe-zeolite catalyst was improved with the temperature increasing.

关 键 词：柴油机 分子筛催化剂 选择性催化还原 轴向分布 数值模拟 

分 类 号：TK421.5[动力工程及工程热物理—动力机械及工程]