Ti-Al-Si-O<em> <sub>x</sub></em>脱硝催化剂载体的组分优化及性能研究

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沈岳松, 纵宇浩, 眭国荣, 韩冰, 祝社民. Ti-Al-Si-O _x脱硝催化剂载体的组分优化及性能研究 . 无机材料学报, 2015, 30(5): 542-548
SHEN Yue-Song, ZONG Yu-Hao, SUI Guo-Rong, HAN Bing, ZHU She-Min. Component Optimization and Performance of Ti-Al-Si-O _x deNO _x Catalyst Carrier . Journal of lnorganic Materials,2015, 30(5): 542-548 复制到剪切板

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Ti-Al-Si-O _x脱硝催化剂载体的组分优化及性能研究

沈岳松, 纵宇浩, 眭国荣, 韩冰, 祝社民

南京工业大学材料科学与工程学院, 南京210009

祝社民, 教授. E-mail:zsm313@njtech.edu.cn

作者简介: 沈岳松(1981-), 男, 副研究员. E-mail: sys-njut@163.com

基金:国家自然科学基金(21106071, 51272105); 教育部博士点基金(20113221120004); 江苏省社会发展科技支撑计划(BE2013718); 江苏省环保科研课题(2012016); 江苏省优势学科资助(PAPD)

摘要

采用挤出成型法制备系列Ti-Al-Si-O _x脱硝催化剂载体, 评价其NH₃选择性催化还原NO的活性。通过正交实验优化Ti-Al-Si-O _x配方, 采用液N₂-BET、ESEM及XRD分别表征载体的比表面积、孔容孔径分布、微观形貌和固相结构; 采用阿基米德法测试载体的吸水率、开气孔率和体积密度。结果表明, 当Ti/Al/Si摩尔比为1:0.2:0.1时, TiAl_0.2Si_0.1O _x载体NH₃-SCR脱除NO活性及轴向抗压碎强度匹配最好。当空速为7200 h^-1, 载体在450~550℃内NH₃-SCR脱除NO效率均>80%, 494℃脱除NO效率达到最大值85.8%; 载体抗压碎强度为6.17 MPa, 比表面积为89.1 m²/g, 开气孔率达63.0%, 吸水率达48.3%, 介孔最可几分布为8.1 nm, 次可几分布为3.7 nm。TiAl_0.2Si_0.1O _x脱硝催化剂载体具备优异的性能。

关键词: Ti-Al-Si-O x脱硝催化剂载体; 组分优化; 正交实验; 性能研究

中图分类号:X701 文献标志码:A 文章编号:1000-324X(2015)05-0542-07

Component Optimization and Performance of Ti-Al-Si-O _x deNO _x Catalyst Carrier

SHEN Yue-Song, ZONG Yu-Hao, SUI Guo-Rong, HAN Bing, ZHU She-Min

College of Materials Science and Engineering, Nanjing Tech University, Nanjing 210009, China

Fund:National Natural Science Foundation of China (21106071, 51272105); New Teachers’Fund for Doctor Stations Sponsored by the Ministry of Education of China (20113221120004); Jiangsu Provincial Science and Technology Supporting Program (BE2013718); Research Subject of Environmental Protection Department of Jiangsu Province of China (2012016); Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)

Abstract

A series of Ti-Al-Si-O _x deNO _x catalyst carriers were prepared by extrusion method and tested for selective catalytic reduction (SCR) of NO with NH₃. The Ti-Al-Si-O _x formulas were designed and optimized by orthogonal experiments, and the specific surface area, pore volume and size distributions, micro-morphology and solid-phase structure of the carriers were characterized by N₂-BET, ESEM and XRD, respectively. Moreover, the water adsorption, open porosity and bulk density of the carriers were measured by Archimedes method. Results showed that the catalytic activity for NH₃-SCR of NO and the axial crush strength of the TiAl_0.2Si_0.1O _x carrier matched the best when the Ti/Al/Si molar ratio was equal to 1:0.2:0.1. Under gas hourly space velocity (GHSV) of 7200 h^-1, the TiAl_0.2Si_0.1O _xobtained more than 80% NO removal in active temperature range of 450-550℃, and obtained the maximum catalytic activity of 85.8% at 494℃. The axial crushing strength of the TiAl_0.2Si_0.1O _x was 6.17 MPa, its specific surface area was 89.1 m²/g, its open porosity was 63.0%, its water adsorption was 48.3%, the most probable meso pore distribution was 8.1 nm and the second probable pore distribution was 3.7 nm. In conclusion, the TiAl_0.2Si_0.1O _x deNO _x catalyst carrier possesses excellent performance.

Keyword: Ti-Al-Si-O x deNO x catalyst carrier; component optimization; orthogonal experiment; performance study

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烟气脱硝是国家“ 十二五” 大气污染治理的重点。选择性催化还原(SCR)脱硝技术成熟、效率高、稳定性好成为当前国内外治理NO_x的主流技术和发展方向^[1]。催化剂为SCR脱硝技术核心, 占SCR系统初投资的40%~60%^[2], 具有超千亿元的脱硝催化剂市场。载体是催化剂必不可少的重要组成部分, 低成本高性能环境友好型载体的研制成为制约脱硝催化剂产业化的关键技术之一。

目前, 脱硝催化剂载体主要有TiO₂^{[3, 4]}、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等。单一组分载体存在催化活性差、机械强度低、烧结性能差、易粉化和热稳定性差等问题, 严重影响脱硝催化剂的活性和稳定性。二元或多元氧化物载体可以弥补单一组分氧化物载体的性能缺陷。Zhao等^[9]研究报道了不同载体负载CeO₂催化剂的脱硝活性为Ce/TiO₂< Ce/TiO₂- 20SiO₂≈ Ce/TiO₂-3.5Al₂O₃< Ce/TiO₂-20SiO₂-3.5Al₂O₃, 固体表面酸性是催化剂NH₃-SCR脱除NO_x的主要活性因素之一^[10], Si和Al的掺入使得复合氧化物表面电荷过剩, 从而增加了表面酸性位^{[11, 12]}。Sabu等^[13]研究表明TiO₂-SiO₂-Al₂O₃三元氧化物与SiO₂-Al₂O₃、SiO₂-TiO₂及Al₂O₃-TiO₂等二元氧化物相比, 其酸量最高。本课题组研制的Ti_0.8Zr_0.2Ce_0.2O_2.4/Al₂O₃-TiO₂- SiO₂催化剂具有优异的NH₃-SCR脱硝性能^[14]。然而, 目前有关Ti-Al-Si-O_x脱硝催化剂载体的系统性研究尚未见报道。

本研究旨在制备高性价比环境友好型Ti-Al-Si-O_x脱硝催化剂载体, 通过正交设计优化载体组分配比, 研究Ti/Al/Si元素配比对载体NH₃-SCR脱除NO活性和轴向抗压碎强度的影响。采用阿基米德法测试载体的开气孔率、吸水率及体积密度, 采用液氮物理吸附/脱附(BET法)、环境扫描电镜(ESEM)、X射线衍射(XRD)等表征催化剂的比表面积、孔容孔径分布、微观形貌及固相结构, 以此确立Ti-Al-Si-O_x载体最优配比。

1 实验方法

1.1 Ti-Al-Si-O_x组分配比设计

选择L₂₅(5⁶)正交表格设计Ti-Al-Si-O_x组分配比, 如表1所述。以Ti、Al、Si三种元素为三因素, 以各元素物质的量为因素水平, 每个因素共设置5水平。其中, Ti因素5水平为: 1(0.2 mol)、2(0.4 mol)、3(0.6 mol)、4(0.8 mol)、5(1 mol); Al因素5水平为: 1(0.05 mol)、2(0.1 mol)、3(0.2 mol)、4(0.3 mol)、5(0.4 mol); Si因素水平与Al因素水平设置相同。其它参数在同一条件下保持不变。正交实验以Ti-Al- Si-O_x选择性催化还原NO的活性≥ 60%的温度区间(简称T_r)和最高活性值(简称η _max)作为评价载体脱硝性能的两个基本参数, 并以载体轴向抗压碎强度(简称S_c, ≥ 6 MPa)作为基准, 以此筛选确立最优载体配比。

表1 正交设计因素水平和实验结果 Table 1 Orthogonal design factor levels and experimental results

1.2 载体制备

按照L₂₅(5⁶) 载体配方设计, 分别称取适量钛白粉(CP, 无锡拓博达钛白制品有限公司), 高粘拟薄水铝石(CP, 山东铝业公司鲁中实业贸易公司化学品氧化铝厂, Al₂O₃≥ 90%), 硅藻土(AR, 国药集团化学试剂有限公司, SiO₂≥ 85%)及羧甲基纤维素(粘结剂)。将上述原料倒入混料机中均匀混合, 快速搅拌30 min后, 过ϕ 250 μ m标准筛造粒。再将造粒好原料放进捏合机中, 添加适量的蒸馏水, 混合练泥2 h, 待陈腐老化和除杂后, 通过挤压成型制备圆柱状载体坯体, 待坯体干燥后, 再将其置入马弗炉中, 以5℃/min升温速度至500℃保温2 h焙烧, 即制备完成Ti-Al-Si-O_x载体样品, 载体尺寸(直径× 长度)为ϕ 3.0 mm× (2.0~8.0) mm。

1.3 载体脱硝活性评价

载体活性测试是在固定床反应器上进行, 反应器为内径8 mm、外径10 mm的石英管, 反应温度由电加热炉通过程序控温仪控制, 量取10 mL载体置于反应器中部。反应气体设定如下: NO_in(930 ppm), NH_3in(930 ppm), O_2in(10vol%)。GHSV为7200 h^-1, 气体总流量为1200 mL/min。活性测试前载体加热至200℃用混合气吹扫30 min, 避免载体的物理吸附影响实验结果。每个测试温度点均稳定反应30 min以上才开始读取[NO]浓度值。采用ECOM- J2KN烟气分析仪在线测定反应前后[NO]浓度值。脱硝活性以反应前后NO转化率表示: NO转化率(%) = (1– [NO]_out/[NO]_in)× 100%。

1.4 性能测试表征

采用阿基米德法测试载体的体积密度、开气孔率和吸水率; 采用压力试验机测试载体的轴向抗压碎强度。

采用日本理学Rigaku D max/RB型X射线衍射仪(XRD)分析载体的固相结构。扫描范围为10º ~80º , Cu Kα 靶(入射光波长为0.154 nm), 管电压40 kV, 管电流40 mA, 扫描速度3^o/min, 扫描步长为0.02° 。

将样品在JFC-1600型离子溅射仪上镀金后, 采用日本电子公司(JEOL)生产的JSM-5900型环境扫描电子显微镜(ESEM)观察载体的微观形貌。

采用美国Micromeritics公司的ASAP 2020M V3.00H型比表面积及微孔分析仪测定载体比表面积及孔容孔径分布, 样品测试前经350℃真空处理3 h, 以N₂为吸附质, 在-196℃进行测试。

2 结果与讨论

2.1 载体活性分析

图1(a~e)表述的是Ti-Al-Si-O_x系列载体NH₃- SCR脱除NO的活性变化曲线。由脱硝活性变化趋势可知, Ti-Al-Si-O_x系列载体催化活性伴随反应温度的升高总体呈勺子状变化趋势。在200~331℃内, 随反应温度的升高, 载体表现较弱的催化活性, 略有增加, 主要是载体对NO物理吸附的贡献。在331~450℃内, 随着反应温度继续上升, Ti-Al-Si-O_x系列载体脱硝活性迅速增加, 主要原因是反应温度升高, 反应气体分子在催化剂表面吸附脱附速率变大, 活化分子数增加, 有效碰撞次数变多, 反应速率也随之变大, NO转化率随之提高^[15]。在450~550℃内, 载体脱硝活性达到最高值, 且随反应温度升高而相对平稳, 为载体的脱硝活性温度窗口; 在测试温度点494℃, 脱硝活性达到极大值。550℃以后, 载体脱硝活性随反应温度升高而明显下降, 一方面可能是NH₃的氧化消耗所致^[16], 另一方面, 载体化学吸附NH₃或NO的能力已经弱于由于温度过高给予NH₃或NO的动能, 造成脱硝活性下降。

在测试温度区间内, Ti-Al-Si-O_x脱硝活性的大小又因各载体组分元素配比不同而表现各异。图2(a~c)分别表述的是由正交实验表1计算得出的脱硝活性温度区间、最佳脱硝效率和抗压碎强度随Ti、Al、Si三因素效应变化的曲线图。由图2可知, 随着Ti含量的增多, NO脱除率和脱硝活性温度区间均先增大后减小再增大, 水平5是最佳值点。随着Al含量的增多, NO脱除率和脱硝活性温度区间均先减小后增大再减小, 水平1是最佳值点。随着Si含量的增多, NO转化率呈减少趋势, 水平1是最佳值点; 脱硝活性温度区间呈先减小后增大再减小, 水平1或3是最佳值点。随着Ti、Al、Si含量的变化, NO脱除率和脱硝活性温度区间变化趋势类似, 且都有最佳值。由表1可知, 影响脱硝活性温度区间及最高活性值的因素顺序均为Ti> Si> Al。综合分析三因素对脱硝活性温度窗口和最佳脱硝效率两指标的影响, 载体组分最佳配比为Ti/Al/Si = 1:0.05:0.05。然而, 载体的轴向抗压碎强度不能满足要求。随着Ti含量的增多, 载体轴向抗压碎强度先增大后减小, 水平2是最佳值点; 随着Al含量的增多, 载体轴向抗压碎强度呈增大趋势, 水平5是最佳值点; 随着Si含量的增多, 载体轴向抗压碎强度先减小后增大再减小, 水平1是最佳值点。由此可得载体轴向抗压碎强度的最佳配比是Ti/Al/Si= 0.4:0.4:0.05, 达到17.2 MPa, 影响载体轴向抗压碎强度的因素顺序为Al> Ti> Si。综合分析各因素对各指标的影响, 载体组分最佳配比为Ti/Al/Si=1:0.2:0.05, 定义此配比为26号样品。

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	图 1 Ti-Al-Si-O_x系列载体NH₃-SCR脱除NO活性变化Fig. 1 Activity variations of Ti-Al-Si-O_x for NH₃-SCR of NO (a) Samples 1-5; (b) Samples 6-10; (c) Samples 11-15; (d) Samples 16-20; (e) Samples 21-25

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	图2 因素效应变化曲线Fig. 2 Factors effect curves (a) DeNO_x active temperature range; (b) Highest deNO_xefficiency; (c) Axial crush strength

图3表述的是经正交实验得出1、6、14、18、23、26号同时满足轴向抗压碎强度且脱硝活性高的样品与最佳理论配比26号样品的脱硝活性对比图。由实验对比可知, 26号样品在低温区间活性变差, 不是最佳活性配比。当Ti/Al/Si元素摩尔比为1:0.2:0.1时, 23号TiAl_0.2Si_0.1O_x载体NH₃-SCR脱除NO效果及载体轴向抗压碎强度匹配最好。当空速为7200 h^-1, 温度为450~550℃, 载体脱除NO效率均> 80%, 最佳活性温度点为494℃, 脱硝效率达到85.8%, 轴向抗压碎强度为6.17 MPa。

2.2 Ti-Al-Si-O_x载体气孔率、体积密度和吸水率

表2分别表述的是10、22、23号载体的吸水率、开气孔率和体积密度。对比数据分析可知, TiO₂含量最少及Al₂O₃含量最多的10号载体体积密度最大, 吸水率和开气孔率最小。TiO₂含量最多及Al₂O₃含量最少的22号载体体积密度最小, 吸水率和开气孔率最大。23号载体的吸水率、开气孔率和体积密度与22号载体相当。TiO₂含量增多及Al₂O₃含量减少可以提高载体的开气孔率和吸水率, 而降低载体体积密度。由表1可知, 23号载体的轴向抗压碎强度几乎为22号载体的2倍, 耐烟气粉尘冲刷能力更强。载体开气孔率和吸水率增大, 有利于反应气体内外扩散传质, 有利于催化活性组分在载体表面的镶嵌负载^[17]。载体密度基本上决定了催化剂的密度, 所制得的载体密度基本上能使相应催化剂的密度控制在1.2~1.5 g/cm³, 能有效克服烟气对催化剂床层的冲击力。鉴于原料成本: 钛白粉> 拟薄水铝石> 硅藻土, 则23号样品性价比最高。

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	图3 Ti-Al-Si-O_x系列载体脱硝活性评价结果Fig. 3 The catalytic activities of the Ti-Al-Si-O_x carriers for NH₃-SCR of NO

表2 载体的吸水率、气孔率和体积密度 Table 2 Water absorption, porosity and bulk density of carrier

2.3 载体比表面积及孔容孔径分布

表3分别给出了23、10及22号样品的比表面积, 并给出了23号TiAl_0.2Si_0.1O_x载体的孔容和平均孔径。可以看出, 10号样品的比表面积较小, 23号与22号比表面积相当。TiAl_0.2Si_0.1O_x载体为介孔材料, 平均孔径为10.9 nm, 具有较大的比表面积和孔容。

图4表述的是23号TiAl_0.2Si_0.1O_x载体的吸附-脱附等温线和孔容孔径分布图。此等温线属IUPAC分类中的IV型, 吸附等温线与脱附等温曲线的互相不重合形成滞回环, 属BJH模型中的H1型^[18]。H1是均匀孔模型, 为直筒孔。临界温度以下, 气体在中孔载体上发生吸附时, 首先形成单分子吸附层; 当单分子层吸附接近饱和时, 开始发生多分子层的吸附特征; 当相对压力达到与发生毛细凝聚的Kelvin半径所对应的特定值(P/P₀=0.66)时开始发生毛细孔凝聚, 出现滞后环。其中, 滞后环的始点, 表示最小毛细孔开始凝聚; 滞后环的终点, 表示最大的孔被凝聚液充满。在中压P/P₀=0.66~0.80阶段, 吸附量随相对压力的增加比较缓慢, 表示孔分布较宽; 在高压(0.90~1.00)阶段, 吸附量上升较快, 反映出载体中大孔或粒子堆积孔情况。从TiAl_0.2Si_0.1O_x载体孔容随孔径变化的曲线可以看出, 分别在3.7 nm和8.1 nm处出现孔容峰, 且8.1 nm处孔容峰最突出, 表示介孔载体存在两处最可几孔分布, 且8.1 nm处孔分布最广。TiAl_0.2Si_0.1O_x载体复杂的多尺寸孔道结构有利于反应气体分子的内外传质。

表3 样品比表面、总孔容及平均孔径 Table 3 Specific surface area, total volume and average pore size of carrier

2.4 ESEM分析

图5为23号TiAl_0.2Si_0.1O_x载体不同放大倍数下的ESEM照片。可以看出, 载体微观结构疏松多孔, 类似珊瑚状结构, 大颗粒是由粒径约为20~35 nm左右的细小纳米颗粒凝集而成, 内部孔结构主要是粒子堆积间隙。细小颗粒为反应气体吸附提供了大量的接触面, 贡献了较大的比表面积。

2.5 XRD固相结构分析

图6分别表述的是钛白粉及10、22、23号载体样品的XRD粉末衍射图谱。对钛白粉XRD图谱分析可知, 2θ 为25.31° 、37.79° 、48.05° 、53.38° 、55.07° 及62.69° 分别对应锐钛矿型TiO₂(PDF 71-1166)的(101)、(004)、(200)、(105)、(211)、(204)晶面, 属四方晶系。掺入Al及Si组分后, 10、22、23号Ti-Al-Si-O_x系列载体的主晶相也为锐钛矿型TiO₂; 另在2θ 为21.81° 出现较弱的特征衍射峰, 对应方石英型SiO₂(PDF 76-941)的(101)晶面; 未观测到明显的Al₂O₃、Al-Si-O_x固溶体及Ti-Al-O_x固溶体晶相衍射峰。与钛白粉XRD特征衍射峰相比, Ti-Al-Si-O_x载体特征衍射峰强度明显减弱, 主要是因为复合氧化物中TiO₂含量降低造成的。鉴于离子尺寸因素的影响^[19]: 由于Ti⁴⁺的离子半径(0.0605 nm)与Al³⁺离子半径(0.0535 nm)满足|(r₁-r₂)/r₁× 100%|< 15%, Al₂O₃与TiO₂有条件形成连续固溶体; Al³⁺离子半径(0.0535 nm)与Si⁴⁺离子半径 (0.04 nm) 满足15%< |(r₁-r₂)/r₁× 100%|< 30%, Al₂O₃与SiO₂可以形成有限固溶体。然而, Ti-Al-Si-O_x系列载体XRD图谱中未检测到明显的Ti-Al-O_x固溶体及Al-Si-O_x固溶体的特征晶相衍射峰, 可能是因为Al₂O₃与TiO₂及SiO₂与Al₂O₃固溶量小, 或以无定型存在, 或以细小纳米晶高度分散不足以分辨。

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	图4 TiAl_0.2Si_0.1O_x的N₂吸附/脱附等温线及孔径分布曲线Fig. 4 N₂ adsorption/desorption isotherms and the BJH pore size distribution plot (inset) of TiAl_0.2Si_0.1O_x

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	图5 TiAl_0.2Si_0.1O_x不同放大倍数的ESEM照片Fig. 5 ESEM photographs of TiAl_0.2Si_0.1O_x with different magnifications

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	图6 钛白粉及Ti-Al-Si-O_x样品的XRD粉末衍射图谱Fig. 6 X-ray diffraction patterns of titanium white powder and Ti-Al-Si-O_x powders (a) 10, Ti:Al:Si=4:4:0.5; (b) 22, Ti:Al:Si=10:1:0.5; (c) 23, Ti:Al:Si=10:2:1

3 结论

Ti-Al-Si-O_x载体NH₃-SCR脱除NO活性高, 轴向抗压碎强度高, 开气孔率大、吸水率大、比表面积较大, 具有合适的孔分布, 为脱硝催化剂提供了优异的载体性能。通过正交设计优化载体组分配比, 实验结果表明: 当Ti/Al/Si元素摩尔比为1:0.2:0.1时, TiAl_0.2Si_0.1O_x载体NH₃-SCR脱除NO的活性及轴向抗压碎强度匹配最好。当空速为7200h^-1, 在450~550℃内, TiAl_0.2Si_0.1O_x载体脱除NO效率均> 80%, 494℃时脱除NO效率达到最大值85.8%; 载体轴向抗压碎强度达6.17 MPa, 比表面积为89.1 m²/g, 开气孔率达63.0%, 吸水率达48.3%, 介孔的最可几分布为8.1 nm, 次可几分布为3.7 nm。

参考文献

View Option

[1]	FORZATTI P. Present status and perspectives in deNO_x SCR catalysis. Applied Catalysis A: General, 2001, 222(1/2): 221-236. [本文引用:1] [JCR: 3.41]
[2]	WANG CHUN-LAN, SONG HAO, HAN DONG-QIN. Development and application of recycling technology of SCR denitration catalytic agent. China Environmental Protection Industry, 2014(4): 22-25. [本文引用:1]
[3]	SHEN YUE-SONG, ZHU SHE-MIN, QIU TAI, et al. Preparation of Ti-Zr-V-O catalytic composite material and its selective catalytic Reduction of NO. Journal of Inorganic Materials, 2009, 24(3): 457-462. [本文引用:1] [JCR: 0.537] [CJCR: 1.106]
[4]	HA HEON PHIL, MADDIGAPU PRATAP REDDY, PULLUR ANIL KUMAR, et al. SO₂ resistant antimony promoted V₂O₅/TiO₂ catalyst for NH₃-SCR of NO_x at low temperatures. Applied Catalysis B: Environmental, 2008, 78(3/4): 301-308. [本文引用:1] [JCR: 5.825]
[5]	XU HAI-TAO, SHEN YUE-SONG, SHAO CHENG-HUA, et al. A novel catalyst of silicon cerium complex oxides for selective catalytic reduction of NO by NH₃. Journal of Rare Earths, 2010, 28(5): 721-726. [本文引用:1] [JCR: 1.363] [CJCR: 0.7325]
[6]	SHEN YUE-SONG, ZHU SHE-MIN, QIU TAI, et al. A novel catalyst of CeO₂/Al₂O₃ for selective catalytic reduction of NO by NH₃. Catalysis Communications, 2009, 11(1): 20-23. [本文引用:1] [JCR: 2.915]
[7]	ZHANG YANG, HE SHENG, DU ZHEN, et al. Experimental study on preparation of the activated carbon-supported vanadium oxide catalyst. Thermal Power Generation, 2014(7): 124-130. [本文引用:1]
[8]	WANG JIAN-CHENG, TIAN DONG, HAN LI-NA, et al. In situ synthesized Cu-ZSM-5/cordierite for reduction of NO. Transactions of Nonferrous Metals Society of China, 2011, 21(2): 353-358. [本文引用:1] [JCR: 0.917] [CJCR: 0.7776]
[9]	ZHAO WEN-RU, TANG YU, WAN YA-PING, et al. Promotion effects of SiO₂ or/and Al₂O₃ doped CeO₂/TiO₂ catalysts for selective catalytic reduction of NO by NH₃. Journal of Hazardous Materials, 2014, 278: 350-359. [本文引用:1] [JCR: 3.925]
[10]	JUNG S M, GRANGE P. Characterization and reactivity of pure TiO₂-SO₄²- SCR catalyst influence of SO₄²- content. Catalysis Today, 2000, 59(3/4): 305-312. [本文引用:1] [JCR: 2.98]
[11]	KOZO TANABE, TAKASHI SUMIYOSHI, KATSUE SHIBATA, et al. A new hypothesis regarding the surface acidity of binary metal oxides. Bulletin of the Chemical Society of Japan, 1974, 47(5): 1064-1066. [本文引用:1] [JCR: 1.387]
[12]	SHEN YUE-SONG. A novel hypothesis of micro-region acid site regarding the surface acidity of binary oxides. RSC Advances, 2012, 2: 5957-5960. [本文引用:1] [JCR: 2.562]
[13]	SABU K R P, RAO K V C, NAIR G G R. A comparative study on the acidic properties and catalytic activities of TiO₂, SiO₂, Al₂O₃, SiO₂-Al₂O₃, SiO₂-TiO₂, Al₂O₃-TiO₂, and TiO₂-SiO₂-Al₂O₃. Bull. Chem. Soc. Jpn. , 1991, 64(6): 1920-1925. [本文引用:1]
[14]	FU WEI-LIANG, SHEN YUE-SONG, ZHU SHE-MIN, et al. Promotional effect of tungsten incorporation on catalytic performance of Ti_{0. 8}Zr_{0. 2}Ce_{0. 2}O_{2. 4}/Al₂O₃-TiO₂-SiO₂ for selective catalytic reduction of NOx by NH₃. Journal of Inorganic Materials, 2014, 29(12): 1294-1300. [本文引用:1] [JCR: 0.537] [CJCR: 1.106]
[15]	甄开吉, 王国甲, 毕颖丽, 等. 催化作用基础. 北京: 科学出版社, 2005: 97-98. [本文引用:1]
[16]	SILVIA S, SEONG M J, PEDRO A, et al. Influence of NH₃ and NO oxidation on the SCR reaction mechanism on copper/nickel and vanadium oxide catalysts supported on alumina and titania. Catalysis Today, 2002, 75(1-4): 331-338. [本文引用:1] [JCR: 2.98]
[17]	SHEN YUE-SONG, ZHU SHE-MIN, QIU TAI. Preparation of meso-porous titania-coating monolithic deNO_x catalyst supporter, Journal of Materials Engineering, 2009(2): 74-78. [本文引用:1]
[18]	黄仲涛. 工业催化剂手册. 北京: 化学工业出版社, 2004: 223-226. [本文引用:1]
[19]	陆佩文. 无机材料科学基础. 南京: 东南大学出版社, 1996: 67-67. [本文引用:1]

2001

3.41

0.0

Applied Catalysis A: General. 2001, 222(1/2):221-236

Present status and perspectives in deNO_x SCR catalysis.

FORZATTI P.

This paper surveys the present status and the perspective of de-NO x SCR catalysis for stationary sources, that is based on the reduction of NO x by NH 3 to form water and nitrogen. After a brief description of the SCR chemistry the characteristics of commercial SCR catalysts, their physico-chemical properties and reactivity, and their performances in both NO x reduction and SO 2 oxidation are presented. The mechanism of the SCR reactions, the mathematical modeling of the reactor and the arrangements of the reactor and process are then described. Finally the emerging technologies for NO x removal and the future perspectives of the SCR catalysis are outlined.

... 选择性催化还原(SCR)脱硝技术成熟、效率高、稳定性好成为当前国内外治理NO_x的主流技术和发展方向^[1] ...

0.0

... 催化剂为SCR脱硝技术核心, 占SCR系统初投资的40%~60%^[2], 具有超千亿元的脱硝催化剂市场 ...

2009

0.537

1.106

Journal of Inorganic Materials. 2009, 24(3):457-462

Preparation of Ti-Zr-V-O catalytic composite material and its selective catalytic Reduction of NO.

SHEN YUE-SONG , ZHU SHE-MIN , QIU TAI

A series of Ti-Zr-V-O catalytic composite materials were prepared by sol-gel method. Effect of doping zirconium on catalytic NO x activities of Ti-V-O composite catalysts was investigated, and effects of doping zirconium on crystal form, crystalline morphology, chemical composition, functional group structure and specific surface area of titanium-vanadium composite oxides were characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Energy spectrum analysis (EDS), Fourier infrared spectrum (FT-IR) and N 2 physical adsorption (BET method) respectively. The experimental results show that doping zirconium can inhibit anatase crystalline transformation, refine grain size, change the crystalline morphology and enhance the solid acidity of Ti-V-O composite catalysts. Consequently, the catalytic properties of Ti-Zr-V-O composite catalysts are improved. In the process of selective catalytic reduction of NO over Ti-Zr-V-O/ATS ceramics monolithic catalysts, using NH 3 as reducing agent, doping zirconium widens the catalytic active zone to high temperature area about 100℃, and the highest NO conversion at 300℃ is increased by 17.3%. Key words： Ti-Zr-V-O catalytic composite materials,sol-gel,doping zirconium,deNO x

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

2008

5.825

0.0

Applied Catalysis B: Environmental. 2008, 78(3/4):301-308

SO₂ resistant antimony promoted V₂O₅/TiO₂ catalyst for NH₃-SCR of NO_x at low temperatures.

HA HEON PHIL , MADDIGAPU PRATAP REDDY , PULLUR ANIL KUMAR

To get the low temperature sulfur resistant V 2 O 5 /TiO 2 catalysts quantum chemical calculation study was carried out. After selecting suitable promoters (Se, Sb, Cu, S, B, Bi, Pb and P), respective metal promoted V 2 O 5 /TiO 2 catalysts were prepared by impregnation method and characterized by X-ray diffraction (XRD) and Brunner Emmett Teller surface area (BET-SA). Se, Sb, Cu, S promoted V 2 O 5 /TiO 2 catalysts showed high catalytic activity for NH 3 selective catalytic reduction (NH 3 -SCR) of NO x carried at temperatures between 150 and 400 °C. The conversion efficiency followed in the order of Se > Sb > S > V 2 O 5 /TiO 2 > Cu but Se was excluded because of its high vapor pressure. An optimal 2 wt% ‘Sb’ loading was found over V 2 O 5 /TiO 2 for maximum NO x conversion, which also showed high resistance to SO 2 in presence of water when compared to other metal promoters. In situ electrical conductivity measurement was carried out for Sb(2%)/V 2 O 5 /TiO 2 and compared with commercial W(10%)V 2 O 5 /TiO 2 catalyst. High electrical conductivity difference (Δ G ) for Sb(2%)/V 2 O 5 /TiO 2 catalyst with temperature was observed. SO 2 deactivation experiments were carried out for Sb(2%)/V 2 O 5 /TiO 2 and W(10%)/V 2 O 5 /TiO 2 at a temperature of 230 °C for 90 h, resulted Sb(2%)/V 2 O 5 /TiO 2 was efficient catalyst. BET-SA, X-ray photoelectron spectroscopy (XPS) and carbon, hydrogen, nitrogen and sulfur (CHNS) elemental analysis of spent catalysts well proved the presence of high ammonium sulfate salts over W(10%)/V 2 O 5 /TiO 2 than Sb(2%)/V 2 O 5 /TiO 2 catalyst.

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

2010

1.363

0.7325

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

2009

2.915

0.0

Catalysis Communications. 2009, 11(1):20-23

A novel catalyst of CeO₂/Al₂O₃ for selective catalytic reduction of NO by NH₃.

SHEN YUE-SONG , ZHU SHE-MIN , QIU TAI

CeO 2 /Al 2 O 3 catalysts supported on an activated-ceramics have been prepared and characterized by N 2 -BET, XRD, TEM and NH 3 -TPD methods. The effects of reaction temperature and the interactions between CeO 2 and Al 2 O 3 on CeO 2 /Al 2 O 3 /ATS for NO selective catalytic reduction with ammonia were studied. Results showed that the catalyst containing 9 wt% Al 2 O 3 and 13 wt% CeO 2 has the highest activity in the temperature range 250–350 °C at a space velocity of 3000 h −1 , and the selective catalytic reduction of NO over CeO 2 /Al 2 O 3 may be an Oxidation–Reduction process.

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

0.0

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

2011

0.917

0.7776

Transactions of Nonferrous Metals Society of China. 2011, 21(2):353-358

In situ synthesized Cu-ZSM-5/cordierite for reduction of NO.

WANG JIAN-CHENG , TIAN DONG , HAN LI-NA

ZSM-5 zeolites were directly synthesized on the surface of honeycomb cordierite substrates by hydrothermal method and certified by XRD and SEM techniques; the adhesion of ZSM-5 coatings was evaluated by ultrasonic vibration. Cu-ZSM-5/cordierite monolithic catalyst was prepared by ion-exchange and impregnation method and applied for the selective catalytic reduction (SCR) of NO by NH 3 using a simulated diesel exhaust. The results show that the cordierite surface is almost completely covered by ZSM-5 crystals and the crystallization time greatly impacts the loadings and adhesion of ZSM-5 coatings on substrate, the NO x removal rate over Cu-ZSM-5/cordierite is above 90% in a temperature range of 240–480 °C. Moreover, Cu-ZSM-5/cordierite prepared by different methods shows a wide temperature window (240–540 °C) with high NO removal activities.

... 目前, 脱硝催化剂载体主要有TiO₂^[3,4]、SiO₂^[5]、Al₂O₃^[6]、活性炭^[7]及堇青石^[8]等 ...

2014

3.925

0.0

Journal of Hazardous Materials. 2014, 278:350-359

Promotion effects of SiO₂ or/and Al₂O₃ doped CeO₂/TiO₂ catalysts for selective catalytic reduction of NO by NH₃.

ZHAO WEN-RU , TANG YU , WAN YA-PING

A series of the CeO 2 -based catalysts loaded on TiO 2 , TiO 2 –SiO 2 , TiO 2 –Al 2 O 3 , and TiO 2 –SiO 2 –Al 2 O 3 supports were prepared by incipient impregnation method for the selective catalytic reduction (SCR) of NO by NH 3 in the presence of oxygen. The SCR activities of the catalysts with different supports increases in the order of Ce/TiO 2 2 –20SiO 2 ≈ Ce/TiO 2 –3.5Al 2 O 3 2 –20SiO 2 –3.5Al 2 O 3 . The Ce/TiO 2 –20SiO 2 –3.5Al 2 O 3 catalyst showed 100% NO conversion in the temperature range of 250–425 °C and 100% N 2 selectivity in the whole temperature range. The catalytic activity of Ce/TiO 2 –20SiO 2 –3.5Al 2 O 3 exhibited good stability and strong resistance to SO 2 and H 2 O poisoning. The co-introduction of SiO 2 and Al 2 O 3 into TiO 2 could increase the amount of chemisorbed oxygen and Lewis acid sites on the surface of catalyst, which should be responsible for the excellent SCR activity.

... Zhao等^[9]研究报道了不同载体负载CeO₂催化剂的脱硝活性为Ce/TiO₂#cod#x0003C ...

2000

2.98

0.0

Catalysis Today. 2000, 59(3/4):305-312

Characterization and reactivity of pure TiO₂-SO₄²- SCR catalyst influence of SO₄²- content.

JUNG S M , GRANGE P.

The modifications of textural and surface properties of sulfated TiO 2 have been investigated by means of XRD, surface area, XPS, Raman, FT-IR, NH 3 -TPD, and catalytic tests in the reduction of NO by NH 3 . According to sulfate content, the isolated sulfate transforms to a polynuclear sulfate type. Between SO 4 2− =3.0 and 6.6 wt.%, the amount of SO species per unit area is almost constant and equal. Total number of acid sites increases with the SO 4 2− content, while the strongest sites are maximum at 1.5 wt.% loading. The areal TOF (turnover frequency, mole NO converted/s m 2 ) is also higher at SO 4 2− =1.5 wt.% and is directly related to the number of strong Lewis acid sites. Accordingly, it is suggested that the strong Lewis site generated by doping TiO 2 with SO 4 2− is responsible for the higher reactivity of TiO 2 –SO 4 2− at high temperature.

... 5Al₂O₃, 固体表面酸性是催化剂NH₃-SCR脱除NO_x的主要活性因素之一^[10], Si和Al的掺入使得复合氧化物表面电荷过剩, 从而增加了表面酸性位^[11,12] ...

1974

1.387

0.0

Bulletin of the Chemical Society of Japan. 1974, 47(5):1064-1066

A new hypothesis regarding the surface acidity of binary metal oxides.

KOZO TANABE , TAKASHI SUMIYOSHI , KATSUE SHIBATA

We have proposed a new hypothesis that the acid sites on binary metal oxides are formed by an excess of a negative or positive charge in the mixed oxides and that whether the charge is excess or not, and whether it is positive or negative, are determined by the coordination numbers and valences of the positive and negative elements in the model structures pictured according to two postulates. The validity of the hypothesis is, in fact, 90% for the 31 kinds of binary oxides tested, much higher than the validity (48%) of Thomas’ hypothesis. The hypothesis explains well the mechanism of the acidity generation of binary oxides and predicts whether the acid sites will be of the Brönsted or the Lewis type.

... 5Al₂O₃, 固体表面酸性是催化剂NH₃-SCR脱除NO_x的主要活性因素之一^[10], Si和Al的掺入使得复合氧化物表面电荷过剩, 从而增加了表面酸性位^[11,12] ...

2012

2.562

0.0

RSC Advances. 2012, 2:5957-5960

A novel hypothesis of micro-region acid site regarding the surface acidity of binary oxides.

SHEN YUE-SONG.

According to Tanabe's hypothesis, a binary oxide exhibits only one acidity type or no acidity. Actually most binary oxides simultaneously exhibit Brønsted and Lewis acidities; Tanabe's hypothesis cannot explain this phenomenon. Taking into account the effects of material structure and the micro-concept of acid sites, on the basis of the Tanabe hypothesis, the author proposes a new hypothesis of micro-region acid sites regarding the surface acidity of binary oxides.

... 5Al₂O₃, 固体表面酸性是催化剂NH₃-SCR脱除NO_x的主要活性因素之一^[10], Si和Al的掺入使得复合氧化物表面电荷过剩, 从而增加了表面酸性位^[11,12] ...

1991

0.0

Bull. Chem. Soc. Jpn.. 1991, 64(6):1920-1925

A comparative study on the acidic properties and catalytic activities of TiO₂, SiO₂, Al₂O₃, SiO₂-Al₂O₃, SiO₂-TiO₂, Al₂O₃-TiO₂, and TiO₂-SiO₂-Al₂O₃.

SABU K R P , RAO K V C , NAIR G G R

Investigations are carried out to have a systematic comparison of the acidic properties and catalytic activities of single oxide TiO 2 , SiO 2 , Al 2 O 3 , their binary oxides and the ternary oxide TiO 2 –SiO 2 –Al 2 O 3 . The acidity distributions are measured by using butylamine titration technique and the test reactions selected for the catalytic activity measurements are alkylation of toluene with 2-propanol and the dehydration of 2-propanol. The single oxides have only low acid strength and are not at all active in catalyzing the alkylation reaction, but are marginally active in the dehydration of 2-propanol. However the binary oxides SiO 2 –TiO 2 and Al 2 O 3 –TiO 2 of 10% by weight of TiO 2 are found to contain very strong acid sites H o ≤ −8.2 and are highly active catalysts in both the test reactions. But TiO 2 –SiO 2 –Al 2 O 3 of 10% by weight of TiO 2 showed the highest acid amount and the highest activity in the aikylation and dehydration reactions compared to the binary oxides. The acid amount and the catalytic activity of the ternary oxide increased with the increase of TiO 2 content upto 50 mol% of TiO 2 and then decreased. The ternary oxide containing 80 mol% of TiO 2 is rich in weak acid sites. The increase of TiO 2 content does not affect the selectivity.

... Sabu等^[13]研究表明TiO₂-SiO₂-Al₂O₃三元氧化物与SiO₂-Al₂O₃、SiO₂-TiO₂及Al₂O₃-TiO₂等二元氧化物相比, 其酸量最高 ...

2014

0.537

1.106

Journal of Inorganic Materials. 2014, 29(12):1294-1300

Promotional effect of tungsten incorporation on catalytic performance of Ti_0.8Zr_0.2Ce_0.2O_2.4/Al₂O₃-TiO₂-SiO₂ for selective catalytic reduction of NOx by NH₃.

FU WEI-LIANG , SHEN YUE-SONG , ZHU SHE-MIN

Series TZC/ATS catalysts and the tungsten-added samples, with Ti 0.8 Zr 0.2 Ce 0.2 O 2.4 (TZC for short) as active component and Al 2 O 3 -TiO 2 -SiO 2 (ATS for short) as catalyst carrier, were prepared by extrusion method. Effects of tungsten incorporation on catalytic performance and tolerance towards K 2 O and CaO poisoning of TZC/ATS for deNO x by NH 3 selective catalytic reduction (NH 3 -SCR) were mainly studied, and anti K 2 O and CaO poisoning abilities between the TZCW0.4/ATS and the V 2 O 5 (WO 3 )/TiO 2 were comparatively analyzed. Moreover, the specific surface, solid-phase structure, morphology and surface acidity of the catalysts were characterized by techniques of N 2 -BET, XRD, SEM and NH 3 -TPD, respectively. Results showed that the TZCW0.4/ATS catalyst exhibited the highest catalytic activity and the best stability for deNO x by NH 3 -SCR when the Ti/Zr/Ce/W molar ratio of the active component was 4:1:1:0.4. Furthermore, tungsten incorporation greatly enhanced the anti K 2 O and CaO poisoning abilities of the TZCW 0.4 /ATS catalyst, and these anti-poisoning abilities of the TZCW 0.4 /ATS were much stronger than those of the V 2 O 5 (WO 3 )/TiO 2 . The promotional effect on catalytic deNO x performance was caused by increased specific surface area and enhanced surface acidity of the TZCW 0.4 /ATS catalyst after tungsten incorporation.

... 4/Al₂O₃-TiO₂- SiO₂催化剂具有优异的NH₃-SCR脱硝性能^[14] ...

2005

0.0

... 在331~450℃内, 随着反应温度继续上升, Ti-Al-Si-O_x系列载体脱硝活性迅速增加, 主要原因是反应温度升高, 反应气体分子在催化剂表面吸附脱附速率变大, 活化分子数增加, 有效碰撞次数变多, 反应速率也随之变大, NO转化率随之提高^[15] ...

2002

2.98

0.0

Catalysis Today. 2002, 75(1-4):331-338

Influence of NH₃ and NO oxidation on the SCR reaction mechanism on copper/nickel and vanadium oxide catalysts supported on alumina and titania.

SILVIA S , SEONG M J , PEDRO A

The influence of ammonia and nitric oxide oxidation on the selective catalytic reduction (SCR) of NO by ammonia with copper/nickel and vanadium oxide catalysts, supported on titania or alumina have been investigated, paying special attention to N 2 O formation. In the SCR reaction, the VTi catalyst had a higher activity than VAl at low temperatures, while the CuNiAl catalyst had a higher activity than CuNiTi. A linear relationship between the reaction rate of ammonia oxidation and the initial reduction temperature of the catalysts obtained by H 2 -TPR showed that the formation rate of NH species in copper/nickel catalysts would be higher than in vanadia catalysts. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) showed that copper/nickel catalysts presented ammonia coordinated on Lewis acid sites, whereas ammonium ion adsorbed on Brønsted acid sites dominated on vanadia catalysts. The NO oxidation experiments revealed that copper/nickel catalysts had an increase of the NO 2 and N 2 O concentrations with the temperature. NO could be adsorbed on copper/nickel catalysts and the NO 2 intermediate species could play an important role in the reaction mechanism. It was suggested that the presence of adsorbed NO 2 species could be related to the N 2 O formation.

... 550℃以后, 载体脱硝活性随反应温度升高而明显下降, 一方面可能是NH₃的氧化消耗所致^[16], 另一方面, 载体化学吸附NH₃或NO的能力已经弱于由于温度过高给予NH₃或NO的动能, 造成脱硝活性下降 ...

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... 载体开气孔率和吸水率增大, 有利于反应气体内外扩散传质, 有利于催化活性组分在载体表面的镶嵌负载^[17] ...

2004

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1996

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... 鉴于离子尺寸因素的影响^[19]: 由于Ti⁴⁺的离子半径(0 ...