分子筛负载Cu–Mn双金属柴油机尾气脱硝催化剂的稳定性（英文）

近年来柴油车尾气排放了大量的氮氧化物(NO_x),其治理技术目前主要基于选择性催化还原(SCR).但是,由于柴油车尾气的温度波动范围较宽,氧气浓度高,汽油车三效催化剂不能用于柴油车尾气脱硝,因此开发一种有效的SCR催化剂去除柴油机尾气中的NO_x至关重要.Cu/分子筛催化剂在尾气温度高于200°C时表现出高的脱硝活性,但低温(<200°C)催化活性仍有待提高.此外,当柴油颗粒过滤器再生时催化剂处于高温高湿环境,而且柴油车尾气中有未完全燃烧的碳氢化合物(HCs)存在.因此,水热稳定性和抗HCs失活性也是催化剂性能的一个重要指标.Cu–Mn共负载可以有效提高催化剂在200°C以下对NO_x的脱除性能,但其稳定性尚未讨论.本文采用离子交换法将Cu–Mn双金属体系负载在ZSM-5和SAPO-34上,考察了Cu–Mn双金属催化剂去除柴油车尾气NO_x的效果,以及催化剂的温度敏感性、水热稳定性和抗HCs性能.通过X射线衍射(XRD)、扫描电镜(SEM)、N_2吸脱附、^(27)Al固体核磁共振(^(27)Al NMR)和X射线光电子能谱(XPS)等手段分析了催化剂活性和稳定性差异的原因,探讨了影响稳定性的关键因素.研究发现,当Cu/Mn比为3:2时,200°C时Cu–Mn/ZSM-5和Cu–Mn/SAPO-34的NO_x转化率分别达到65%和90%.当催化剂水热老化处理后,或在反应气体中通入C_3H_6后,Cu–Mn/SAPO-34对NO_x的去除率比Cu–Mn/ZSM-5稳定.SEM和物理结构分析结果表明,水热老化处理和含C_3H_6气氛的SCR反应后,Cu–Mn/ZSM-5发生了明显的团聚,且BET比表面积和孔容减小;而Cu–Mn/SAPO-34未发生团聚现象,且保持较好的物理结构.因此,Cu–Mn/ZSM-5的团聚以及物理结构的破坏可能是其稳定性低的原因之一.XRD结果表明,水热老化处理后Cu–Mn/ZSM-5晶体结构无明显变化,Cu–Mn/SAPO-34的结晶度有所提高.含C_3H_6气氛的SCR反应后,两种催化剂仍然保持分子筛结构的特征峰,表现出较好的晶型结构,C_3H_6不会对催化剂的结晶度和晶体结构产生破坏作用.结合SEM图像发现水热老化处理提高了Cu–Mn/SAPO-34的结晶度并提高其低温活性.27Al NMR结果表明,两种催化剂在水热老化处理和含C_3H_6气氛的SCR反应后,四面体配位Al的峰面积几乎没有明显的改变,表明反应后催化剂并未发生明显的脱铝现象,仍然保持较好的结构稳定性.这与之前研究中Cu/ZSM-5反应后四面体配位的Al原子明显减少的结果不同.因此,Mn的加入可以缓解催化剂的脱铝,提高稳定性.XPS结果表明,水热老化处理和含C_3H_6气氛的SCR反应均使得Cu–Mn/ZSM-5上八面体配位的Cu^(2+)明显降低,Cu^+和八面体配位的Cu^(2+)之间的氧化还原循环受到明显抑制.而在Cu–Mn/SAPO-34表面,Cu原子浓度高度稳定,SCR反应中Cu^+和Cu^(2+)保持良好的氧化还原循环.因此,稳定的物理结构和Cu物种是催化剂稳定性的两个重要因素.

Potential Mechanism of Danggui Buxue Decoction in Treating Iron Deficiency Anemia Based on Network Pharmacology and Molecular Docking Technology

[Objectives]To explore the potential mechanism of Danggui Buxue Decoction in treating the iron deficiency anemia(IDA)based on network pharmacology and molecular docking technology.[Methods]The active components and target proteins of Danggui Buxue Decoction were searched in databases such as TCMSP,OMIM,GeneCards,Drugbank,String,Metascape,etc.,and the target proteins shared with IDA were screened out,and the information about the signal pathways and biological functions of these target proteins was obtained.[Results]17 active components of Danggui Buxue Decoction and 24 potential targets for the treatment of IDA were obtained.With the aid of String database and Cytoscape software,the protein interaction network was obtained and the network topology analysis was performed.Four potential core targets with higher scores were obtained,namely F2,NOS2,NOS3,and PPARG.Using the Metascape database,GO function enrichment analysis and KEGG pathway enrichment analysis were performed on the potential targets of Danggui Buxue Decoction in the treatment of IDA,and the important biological processes,cell composition,molecular functions and signal pathways related to the target were screened through the R language.The results show that biological processes are related to positive regulation of growth,cell composition is related to membrane microdomain,and molecular functions are related to oxidoreductase activity.The signal pathways involved are mainly AGE-RAGE signal pathway,TNF signal pathway and IL-17 signal pathway.Finally,the molecular docking results confirmed that the active components of Danggui Buxue Decoction have a good binding ability with the target.[Conclusions]Danggui Buxue Decoction treats the IDA through multiple components,multiple targets,multiple signal pathways,and multiple biological functions.