V-Ti基脫硝催化劑去除汞和PCDDs/PCDFs的研究現狀

田軍吉,楊勝芬，陸　鄒，石　宇

(1.貴州省六盤水市鐘山區經濟和信息化局,貴州 六盤水 553001;2.信和匯金信息咨詢(北京)有限公司,貴州 六盤水 553001)

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綜述與展望

V-Ti基脫硝催化劑去除汞和PCDDs/PCDFs的研究現狀

田軍吉1*,楊勝芬2，陸鄒1，石宇1

(1.貴州省六盤水市鐘山區經濟和信息化局,貴州 六盤水 553001;2.信和匯金信息咨詢(北京)有限公司,貴州 六盤水 553001)

摘要：將柔軟纖維與折皺鋼網復合制成波紋式支撐骨架，將V-Ti基脫硝催化劑負載到波紋式支撐骨架上制成整體波紋式脫硝催化劑。介紹V-Ti基波紋式整體脫硝催化劑的主要制備工藝、優點以及國內外對V-Ti基波紋式整體脫硝催化劑的研究現狀；對V-Ti基脫硝催化劑與貴金屬脫硝催化劑的制造成本以及PCDDs/PCDFs催化分解效果進行對比，兩者具有相同的催化分解效果，V-Ti基脫硝催化劑成本低得多；活性組分、V質量分數以及活性溫度不同，V-Ti基脫硝催化劑催化分解PCDDs/PCDFs的效果也不同，催化分解率最高可達97.7%；研究者得出V-Ti基脫硝催化劑催化氧化Hg0的不同效果，介紹V-Ti基脫硝催化劑催化氧化Hg0的研究現狀。

關鍵詞：三廢處理與綜合利用；V-Ti基脫硝催化劑；波紋式脫硝催化劑；汞；PCDDs/PCDFs

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

目前，火電廠、高爐轉爐煉鐵和煉鋼、水泥行業燃煤煙氣脫硝處理最有效的手段是SCR噴氨脫硝系統[1-9 ]。SCR噴氨系統核心是脫硝催化劑，工業常用的脫硝催化劑為V-Ti基催化劑，其催化反應活性溫度窗口寬，為(300～420)℃。脫硝催化劑使用較多的是蜂窩式和波紋式，波紋式脫硝催化劑具有接觸面積和壓降大的特點，備受燃煤工廠青睞。研究發現，V-Ti基催化劑不僅可用于煙氣脫硝處理，還可將煙氣中PCDDs/PCDFs催化氧化分解為H2O、CO2和HCl[10-11]，將Hg0催化氧化為Hg2+[12]。

本文綜述波紋式脫硝催化劑的制備工藝、主要特點以及脫硝催化劑催化分解PCDDs/PCDFs和催化氧化汞的主要特性。

1波紋式脫硝催化劑的特點及制備工藝

波紋式脫硝催化劑屬非均質催化劑，以柔軟纖維和折皺鋼網復合制成載體，將活性組分V2O5和V2O5-WO3等涂覆在載體上而制成。波紋式脫硝催化劑以玻璃纖維、陶瓷纖維或復合式載體作為支撐骨架，結構堅硬，承載能力強，還具有以下特點[13]：(1) 主要采用玻璃纖維作為基體材料，與傳統的蜂窩式和板式脫硝催化劑相比，在制造工藝和結構上，融合了兩種催化劑的優點；(2) 具有較大的比表面積，脫硝率高于90%，同體積條件下，催化效率優于其他脫硝催化劑；(3) 相同的催化效率，波紋式催化劑使用的活性原料少，每立方米質量比蜂窩式輕(50～100) kg，以100 m3計算，催化劑原料使用量降低(5～10) t；(4) 制備工藝相對簡單，生產自動化程度高。

自20世紀60年代末開始，日本的三菱、武田化工和日立三家公司研制出以TiO2為基材的催化劑，并逐漸取代Pt-Rh和Pt系列催化劑。該類催化劑主要由V2O5(WO3)、Fe2O3、CrOx、CuO、MnOx、MoO3、NiO和MgO等金屬氧化物或有聯合作用的混和物構成，通常以TiO2、ZrO2、Al2O3、SiO2和AC等作為載體，與SCR系統中的液氨或CO(NH2)2等還原劑發生還原反應，成為電廠SCR脫硝工程中應用較廣泛的主流催化劑產品。

國內主流SCR脫硝催化劑核心技術為美國、日本、韓國、丹麥和德國等國家壟斷，技術壁壘高，我國主要靠高成本引進技術進行生產經營。大榮環保科技有限公司引進韓國先進技術,建成國內首個9 000 m3·a-1波紋式脫硝催化劑項目，現已在西安經濟開發區啟源裝備園區投產。

2脫硝催化劑催化分解PCDDs/PCDFs

PCDDs/PCDFs化學性質相對穩定，對生物具有很大的毒害性，因此，如何去除PCDDs/PCDFs的研究受到重視。能催化分解PCDDs/PCDFs的催化劑有貴金屬催化劑和過渡金屬催化劑，雖然貴金屬催化劑催化分解PCDDs/PCDFs的效率最高可達90%，但貴金屬資源稀缺，價格昂貴，在批量生產和應用中受到限制；以過渡金屬作為催化劑活性組分的主要有VOx、MnOx、CrOx和FeOx等，其中，VOx催化活性最高，V2O5/TiO2催化劑分解PCDDs/PCDFs的效果最好[14]。V2O5-WO3/TiO2催化劑可同時用于催化還原NOx和催化分解PCDDs/PCDFs[15]。

3脫硝催化劑催化氧化汞的性能

燃煤產生的汞約占人為釋放量的30%，在燃煤煙氣中，汞通常以單質汞Hg0、氣態二價汞Hg2+及固態顆粒汞Hgp形式存在，其中，Hg0約占煙氣中汞含量的70%[25]。Hg2+與固態顆粒汞Hgp可通過濕法脫硫、煙氣除塵和MCFB煙氣凈化系統去除[26-27]。但Hg0易揮發且不溶于水，可通過吸附劑除去煙氣中的Hg0[28-32]。通過對煤采用沉重分離、程序升溫熱解、酸性提取和SSE技術等研究無煙煤、褐煤和瀝青煤釋放汞的溫度條件以及吸收方法進行預處理[33]，研究[34-36]發現，在溫度低于150℃、(150～250)℃、(250～400)℃和(400～600)℃時，汞分別以單質汞Hg0、HgCl2、HgS和硫鐵礦鍵配位Hg形式釋放，HNO3提取法對除去硫鐵鍵配位汞具有較好的效果。工業用V-Ti基脫硝催化劑通過催化氧化能夠有效地將Hg0氧化成Hg2+[37-38 ]。

4結語與展望

雖然V系脫硝催化劑在催化氧化汞和催化分解PCDDs/PCDFs方面已有研究，但V-Ti基催化劑催化氧化Hg0和催化分解PCDDs/PCDFs的條件與催化還原NOx的條件存在差異，一是活性溫度不同，催化氧化Hg0的最佳活性溫度為(300～350)℃，催化分解PCDDs/PCDFs的最佳活性溫度為(200～300)℃，而催化還原NOx的最佳活性溫度為(300～420)℃；二是修飾劑的影響，在V-Ti基催化劑中加入修飾成分WO3(MoO3)后有利于促進Hg0和NOx的催化氧化還原反應，但對PCDDs/PCDFs的催化分解有抑制作用。研究V-Ti基催化劑催化分解PCDDs/PCDFs時，PCDDs/PCDFs主要是采用多氯苯和芳香烴混合而成的模擬氣體進行研究，所得實驗結果可能存在一定偏差。針對V-Ti基催化劑應用技術研究還有待進一步深入：

(1) 深入對V-Ti基催化劑成型工藝研究。雖然在國外波紋式V-Ti基脫硝催化劑技術已成熟，但由于國內煙氣成分和相應成分含量不同，因此，研究適合國內生產的波紋式V-Ti基脫硝催化劑應用技術或催化劑成型產品迫在眉睫。

(2) 深入對V-Ti基催化劑催化氧化Hg0和催化分解PCDDs/PCDFs的機理及影響因素研究。研究加入不同修飾劑修飾V-Ti基催化劑催化氧化Hg0的機理影響，進一步提高V-Ti基催化劑催化氧化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的機理和影響因素。

(3) 深入對工業用V-Ti催化劑改性研究。加深對現有V-Ti基催化劑改性研究，使改性后的V2O5-WO3(MoO3)/TiO2催化劑在最佳脫硝條件下能同時得到催化氧化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

作者簡介：田軍吉，1987年生，男，貴州省銅仁市人，主要從事新型環保材料、工業煙氣排放后處理技術和柴油煙氣催化凈化研究。

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

中圖分類號：TQ426.6;X701

文獻標識碼：A

文章編號：1008-1143(2016)05-0025-06

通訊聯系人：田軍吉。