V-Ti基脱硝催化剂去除汞和PCDDs/PCDFs的研究现状

田军吉,杨胜芬，陆　邹，石　宇

(1.贵州省六盘水市钟山区经济和信息化局,贵州 六盘水 553001;2.信和汇金信息咨询(北京)有限公司,贵州 六盘水 553001)



综述与展望

V-Ti基脱硝催化剂去除汞和PCDDs/PCDFs的研究现状

田军吉1*,杨胜芬2，陆邹1，石宇1

(1.贵州省六盘水市钟山区经济和信息化局,贵州 六盘水 553001;2.信和汇金信息咨询(北京)有限公司,贵州 六盘水 553001)

摘要：将柔软纤维与折皱钢网复合制成波纹式支撑骨架，将V-Ti基脱硝催化剂负载到波纹式支撑骨架上制成整体波纹式脱硝催化剂。介绍V-Ti基波纹式整体脱硝催化剂的主要制备工艺、优点以及国内外对V-Ti基波纹式整体脱硝催化剂的研究现状；对V-Ti基脱硝催化剂与贵金属脱硝催化剂的制造成本以及PCDDs/PCDFs催化分解效果进行对比，两者具有相同的催化分解效果，V-Ti基脱硝催化剂成本低得多；活性组分、V质量分数以及活性温度不同，V-Ti基脱硝催化剂催化分解PCDDs/PCDFs的效果也不同，催化分解率最高可达97.7%；研究者得出V-Ti基脱硝催化剂催化氧化Hg0的不同效果，介绍V-Ti基脱硝催化剂催化氧化Hg0的研究现状。

关键词：三废处理与综合利用；V-Ti基脱硝催化剂；波纹式脱硝催化剂；汞；PCDDs/PCDFs

CLC number:TQ426.6;X701Document code: AArticle ID: 1008-1143(2016)05-0025-06

目前，火电厂、高炉转炉炼铁和炼钢、水泥行业燃煤烟气脱硝处理最有效的手段是SCR喷氨脱硝系统[1-9 ]。SCR喷氨系统核心是脱硝催化剂，工业常用的脱硝催化剂为V-Ti基催化剂，其催化反应活性温度窗口宽，为(300～420)℃。脱硝催化剂使用较多的是蜂窝式和波纹式，波纹式脱硝催化剂具有接触面积和压降大的特点，备受燃煤工厂青睐。研究发现，V-Ti基催化剂不仅可用于烟气脱硝处理，还可将烟气中PCDDs/PCDFs催化氧化分解为H2O、CO2和HCl[10-11]，将Hg0催化氧化为Hg2+[12]。

本文综述波纹式脱硝催化剂的制备工艺、主要特点以及脱硝催化剂催化分解PCDDs/PCDFs和催化氧化汞的主要特性。

1波纹式脱硝催化剂的特点及制备工艺

波纹式脱硝催化剂属非均质催化剂，以柔软纤维和折皱钢网复合制成载体，将活性组分V2O5和V2O5-WO3等涂覆在载体上而制成。波纹式脱硝催化剂以玻璃纤维、陶瓷纤维或复合式载体作为支撑骨架，结构坚硬，承载能力强，还具有以下特点[13]：(1) 主要采用玻璃纤维作为基体材料，与传统的蜂窝式和板式脱硝催化剂相比，在制造工艺和结构上，融合了两种催化剂的优点；(2) 具有较大的比表面积，脱硝率高于90%，同体积条件下，催化效率优于其他脱硝催化剂；(3) 相同的催化效率，波纹式催化剂使用的活性原料少，每立方米质量比蜂窝式轻(50～100) kg，以100 m3计算，催化剂原料使用量降低(5～10) t；(4) 制备工艺相对简单，生产自动化程度高。

自20世纪60年代末开始，日本的三菱、武田化工和日立三家公司研制出以TiO2为基材的催化剂，并逐渐取代Pt-Rh和Pt系列催化剂。该类催化剂主要由V2O5(WO3)、Fe2O3、CrOx、CuO、MnOx、MoO3、NiO和MgO等金属氧化物或有联合作用的混和物构成，通常以TiO2、ZrO2、Al2O3、SiO2和AC等作为载体，与SCR系统中的液氨或CO(NH2)2等还原剂发生还原反应，成为电厂SCR脱硝工程中应用较广泛的主流催化剂产品。

国内主流SCR脱硝催化剂核心技术为美国、日本、韩国、丹麦和德国等国家垄断，技术壁垒高，我国主要靠高成本引进技术进行生产经营。大荣环保科技有限公司引进韩国先进技术,建成国内首个9 000 m3·a-1波纹式脱硝催化剂项目，现已在西安经济开发区启源装备园区投产。

2脱硝催化剂催化分解PCDDs/PCDFs

PCDDs/PCDFs化学性质相对稳定，对生物具有很大的毒害性，因此，如何去除PCDDs/PCDFs的研究受到重视。能催化分解PCDDs/PCDFs的催化剂有贵金属催化剂和过渡金属催化剂，虽然贵金属催化剂催化分解PCDDs/PCDFs的效率最高可达90%，但贵金属资源稀缺，价格昂贵，在批量生产和应用中受到限制；以过渡金属作为催化剂活性组分的主要有VOx、MnOx、CrOx和FeOx等，其中，VOx催化活性最高，V2O5/TiO2催化剂分解PCDDs/PCDFs的效果最好[14]。V2O5-WO3/TiO2催化剂可同时用于催化还原NOx和催化分解PCDDs/PCDFs[15]。

3脱硝催化剂催化氧化汞的性能

燃煤产生的汞约占人为释放量的30%，在燃煤烟气中，汞通常以单质汞Hg0、气态二价汞Hg2+及固态颗粒汞Hgp形式存在，其中，Hg0约占烟气中汞含量的70%[25]。Hg2+与固态颗粒汞Hgp可通过湿法脱硫、烟气除尘和MCFB烟气净化系统去除[26-27]。但Hg0易挥发且不溶于水，可通过吸附剂除去烟气中的Hg0[28-32]。通过对煤采用沉重分离、程序升温热解、酸性提取和SSE技术等研究无烟煤、褐煤和沥青煤释放汞的温度条件以及吸收方法进行预处理[33]，研究[34-36]发现，在温度低于150℃、(150～250)℃、(250～400)℃和(400～600)℃时，汞分别以单质汞Hg0、HgCl2、HgS和硫铁矿键配位Hg形式释放，HNO3提取法对除去硫铁键配位汞具有较好的效果。工业用V-Ti基脱硝催化剂通过催化氧化能够有效地将Hg0氧化成Hg2+[37-38 ]。

4结语与展望

虽然V系脱硝催化剂在催化氧化汞和催化分解PCDDs/PCDFs方面已有研究，但V-Ti基催化剂催化氧化Hg0和催化分解PCDDs/PCDFs的条件与催化还原NOx的条件存在差异，一是活性温度不同，催化氧化Hg0的最佳活性温度为(300～350)℃，催化分解PCDDs/PCDFs的最佳活性温度为(200～300)℃，而催化还原NOx的最佳活性温度为(300～420)℃；二是修饰剂的影响，在V-Ti基催化剂中加入修饰成分WO3(MoO3)后有利于促进Hg0和NOx的催化氧化还原反应，但对PCDDs/PCDFs的催化分解有抑制作用。研究V-Ti基催化剂催化分解PCDDs/PCDFs时，PCDDs/PCDFs主要是采用多氯苯和芳香烃混合而成的模拟气体进行研究，所得实验结果可能存在一定偏差。针对V-Ti基催化剂应用技术研究还有待进一步深入：

(1) 深入对V-Ti基催化剂成型工艺研究。虽然在国外波纹式V-Ti基脱硝催化剂技术已成熟，但由于国内烟气成分和相应成分含量不同，因此，研究适合国内生产的波纹式V-Ti基脱硝催化剂应用技术或催化剂成型产品迫在眉睫。

(2) 深入对V-Ti基催化剂催化氧化Hg0和催化分解PCDDs/PCDFs的机理及影响因素研究。研究加入不同修饰剂修饰V-Ti基催化剂催化氧化Hg0的机理影响，进一步提高V-Ti基催化剂催化氧化Hg0的效率；研究催化分解真正的PCDDs/PCDFs，真正了解催化分解PCDDs/PCDFs的机理和影响因素。

(3) 深入对工业用V-Ti催化剂改性研究。加深对现有V-Ti基催化剂改性研究，使改性后的V2O5-WO3(MoO3)/TiO2催化剂在最佳脱硝条件下能同时得到催化氧化Hg0和催化分解PCDDs/PCDFs的效率。

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Research status of V-Ti-based denitrification catalysts for removal of Hg and PCDDs/PCDFs

Tian Junji1*, Yang Shengfen2, Lu Zou1, Shi Yu1

(1.Economic and Information Bureau of Zhong Mountain Area of Liupanshui City, Liupanshui 553001,Guizhou, China; 2.Xinhe Huijin Consulting (Beijing) Co. Ltd, Liupanshui 553001, Guizhou, China)

Abstract:The composite corrugated support frames were prepared by using the soft fibers and creasing steel mesh.The monolithic corrugated denitrification catalysts were prepared by loading V-Ti-based De-NOx catalysts onto corrugated support frames.The current major preparation processes,main advantages and research status of V-Ti-based corrugated denitrification catalysts at home and abroad were reviewed.Compared V-Ti-based denitrification catalysts with noble metal denitrification catalysts,both catalysts possessed the same catalytic decomposition effects of PCDDs/PCDFs,but the manufacturing cost of V-Ti-based denitrification catalysts was lower than those of noble metal denitrification catalysts.V-Ti-based denitrification catalysts with different active components,vanadium contents and reaction activity temperatures exhibited different catalytic decomposition effects of PCDDs/PCDFs.The highest catalytic decomposition rate was 97.7%.The researchers obtained different catalytic effects of V-Ti-based denitrification catalysts for oxidation of Hg0.The research status of V-Ti-based denitrification catalyst for catalytic oxidation of Hg0 oxidation was introduced.

Key words:three waste disposal and comprehensive utilization; V-Ti based denitrification catalyst; corrugated denitrification catalyst; Hg; PCDDs/PCDFs

收稿日期：2015-11-12；修回日期：2016-04-12

作者简介：田军吉，1987年生，男，贵州省铜仁市人，主要从事新型环保材料、工业烟气排放后处理技术和柴油烟气催化净化研究。

doi:10.3969/j.issn.1008-1143.2016.05.005 10.3969/j.issn.1008-1143.2016.05.005

中图分类号：TQ426.6;X701

文献标识码：A

文章编号：1008-1143(2016)05-0025-06

通讯联系人：田军吉。