TiO_2光催化净化城市隧道中NO_x的行为及经济性
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摘要
考察了TiO_2光催化降解模拟城市隧道尾气中NO_x的催化行为,并以一个长度为1km和高度为5m的双向两车道城市隧道为研究对象,分析了其应用的经济性.结果表明,煅烧温度为400℃制备的Ti O_2-400催化剂的NO吸附性能和光催化性能最佳,NO_x最大转化率为30%.不同的气体组成会显著影响光催化剂对NO_x的吸附和光催化性能,其中对于NO竞争性吸附抑制效应的影响为CH_4≈CO_2>CO,而对于光催化性能的促进效应影响为CO>CH_4>CO_2.增大紫外光辐照度可提高光催化活性,但降低了催化剂的稳定性.紫外光辐照度为6.4μW/cm~2为合适的光照强度.增加催化剂的用量可显著增强NO的吸附性能和光降解NO_x的稳定性.当催化剂用量为15mg/cm~2时,NO吸附容量为0.88mg/g,催化剂的稳定时间可达110min.通过简要分析该技术的经济性,表明光催化降解城市隧道NO_x的成本较低,具有良好的经济性.
Photocatalytic behavior of NO removal on TiO_2 was carried out in the simulated urban tunnel exhaust. The economy of its application was analyzed for an urban tunnel with length of 1km and height of 5m. TiO_2 calcined at 400(TiO℃2-400) showed the best adsorption and photocatalytic performance among the samples. The maximum NO_x conversion of 30% was obtained on TiO_2-400. NO_x adsorption and photocatalytic performance was significantly influenced by various feeding gases. The inhibition of NO_x adsorption decreased in the order of CH_4≈CO_2>CO. The promotion of removal efficiency of NO_x was ranked as CO >CH_4>CO_2. When the light irradiance increased, the photocatalytic activity and stability of catalyst were enhanced and decreased, respectively. Light irradiance of 6.4ugW/cm~2 is the appropriate illumination intensity for photocatalysis of DeNO_x. Both NO adsorption capacity and lifetime of catalyst were significantly promoted with the increase of catalyst usage. When catalyst dosage was 15mg/cm~2, the adsorption capacity of NO was 0.88mg/g, and the stabilization time of the catalyst was 110 min. This technology has characteristics with low cost and good economy.
Photocatalytic behavior of NO removal on TiO_2 was carried out in the simulated urban tunnel exhaust. The economy of its application was analyzed for an urban tunnel with length of 1km and height of 5m. TiO_2 calcined at 400(TiO℃2-400) showed the best adsorption and photocatalytic performance among the samples. The maximum NO_x conversion of 30% was obtained on TiO_2-400. NO_x adsorption and photocatalytic performance was significantly influenced by various feeding gases. The inhibition of NO_x adsorption decreased in the order of CH_4≈CO_2>CO. The promotion of removal efficiency of NO_x was ranked as CO >CH_4>CO_2. When the light irradiance increased, the photocatalytic activity and stability of catalyst were enhanced and decreased, respectively. Light irradiance of 6.4ugW/cm~2 is the appropriate illumination intensity for photocatalysis of DeNO_x. Both NO adsorption capacity and lifetime of catalyst were significantly promoted with the increase of catalyst usage. When catalyst dosage was 15mg/cm~2, the adsorption capacity of NO was 0.88mg/g, and the stabilization time of the catalyst was 110 min. This technology has characteristics with low cost and good economy.
引文
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[2]肖益民,盘晓红,张锦鹏.连续公路隧道空气污染物窜流影响的模型试验系统设计[J].中国公路学报,2015,28(11):90-97.Xiao Y M,Pan X H,Zhang J P.Model test system design of channeling effects of air pollutants in continuous road tunnels[J].China Journal of Highway and Transport,2015,28(11):90-97.
[3]王伯光,吕万明,周炎,等.城市隧道汽车尾气中多环芳烃排放特征的研究[J].中国环境科学,2007,27(4):482-487.Wang B G,LǚW M,Zhou Y,et al.Emission characteristic of PAHs composition in motor vehicles exhaust of city tunnel[J].China Environmental Science,2007,27(4):482-487.
[4]王成辉,闫琨,韩新宇,等.高原城市昆明公路隧道大气中PM_(2.5)理化特征分析[J].环境科学,2017,38(12):4968-4975.Wang C H,Yan K,Han X Y,et al.Physico-chemical characteristic analysis of PM_(2.5) in the highway tunnel in the Plateau City of Kunming[J].Environmental Science,2017,38(12):4968-4975.
[5]位楠楠,刘卫,肖德涛,等.隧道大气细颗粒物及其元素的粒径分布特征[J].环境科学研究,2011,24(5):475-481.Wei N N,Liu W,Xiao D T,et al.Size distribution characteristics and elemental composition of airborne fine particles inside a tunnel[J].Research of Environmental Sciences,2011,24(5):475-481.
[6]Kristensson A,Johansson C,Westerholm R,et al.Real-world traffic emission factors of gases and particles measured in a road tunnel in Stockholm,Sweden[J].Atmospheric Environment,2004,38(5):657-673.
[7]Indrehus O,Vassbotn P.CO and NO_2pollution in a long two-way traffic road tunnel:investigation of NO_2/NO_x ratio and modelling of NO_2 concentration[J].Journal of Environmental Monitoring,2001,3(2):221-225.
[8]窦鸿文,明廷臻,许杰,等.城市立体交通系统中污染物传播特性数值模拟[J].中国环境科学,2018,38(1):51-58.Dou H W,Ming T Z,Xu J,et al.Numerical simulation of pollutant propagation characteristics in a three-dimensional urban traffic system[J].China Environmental Science,2018,38(1):51-58.
[9]黄青,宋韬,王伯光,等.城市隧道源排放清单建立方法[J].中国环境科学,2018,38(8):2898-2902.Huang Q,Song T,Wang B T,et al.Method to establish the emission inventory for urban tunnel source[J].China Environmental Science,2018,38(8):2898-2902.
[10]中国环境科学研究院.环境空气质量标准[M].北京:中国环境科学出版社,2012:71.Chinese Research Academy of Environmental Sciences.Ambient air quality standard[M].Beijing:China Environmental Science Press,2012:71.
[11]Guerrini G L.Photocatalytic performances in a city tunnel in Rome:NO_x monitoring results[J].Construction and Building Materials,2012,27:165-175.
[12]Hunger M,Hüsken G,Brouwers H J H.Photocatalytic degradation of air pollutants-From modeling to large scale application[J].Cement and Concrete Research,2010,40(2):313-320.
[13]Maggos T,Plassais A,Bartzis J,et al.Photocatalytic degradation of NO_x in a pilot street canyon configuration using TiO_2-mortar panels[J].Environmental Monitoring and Assessment,2008,136:35-44.
[14]Lasek J,Yu Y,Wu J C S.Removal of NO_x by photocatalytic processes[J].Journal of Photochemistry and Photobiology C:Photochemistry Reviews,2013,14:29-52.
[15]王元瑞.以TiO_2为基质复合氧化物功能材料的合成及应用研究[D].吉林大学,2013.Wang Y R.Synthesis and application of TiO_2 based composite oxides[D].Jilin University,2013.
[16]刘文芳,周汝利,王燕子.光催化剂TiO_2改性的研究进展[J].化工进展,2016,35(8):2446-2454.Liu W F,Zhou R L,Wang Y Z.Research progress on modification of TiO_2 photocatalyst[J].Chemical Industry and Engineering Progress,2016,35(8):2446-2454.
[17]汪成建.TiO_2晶型控制及复合光催化剂性能研究[D].天津:天津大学,2003.Wang C J.Study on crystal form control of TiO_2 and properties of composite photocatalysts[D].Tianjin:Tianjin University,2003.
[18]Roy S,Aarthi T,Hegde M S,et al.Kinetics of photocatalytic reduction of NO by CO with Pd2+-ion-substituted nano-TiO_2[J].Industrial&Engineering Chemistry Research,2007,46(17):5798-5802.
[19]Roy S,Hegde M S,Ravishankar N,et al.Creation of redox adsorption sites by Pd2+ion substitution in nano TiO_2 for high photocatalytic activity of CO oxidation,NO reduction,and NO decomposition[J].Journal of Physical Chemistry C,2007,111(23):8153-8160.
[20]Bowering N,Croston D,Harrison P G,et al.Silver modified degussa P25 for the photocatalytic removal of nitric oxide[J].International Journal of Photoenergy,2007,(2007):1-8.
[21]Bowering N,Walker G S,Harrison P G,Photocatalytic decomposition and reduction reactions of nitric oxide over Degussa P25[J].Applied Catalysis B:Environmental,2006,62(3/4):208-216.
[22]Mikhaylov R V,Lisachenko A A,Shelimov B N,et al.FTIR and TPDanalysis of surface species on a TiO_2 photocatalyst exposed to NO,CO,and NO-CO mixtures:Effect of UV-vis light irradiation[J].Journal of Physical Chemistry C,2009,113(47):20381-20387.
[23]Wu Y T,Yu Y H,Nguyen V H,et al.In-situ FTIR spectroscopic study of the mechanism of photocatalytic reduction of NO with methane over Pt/TiO_2 photocatalysts[J].Research on Chemical Intermediates,2015,41:2153-2164.
[24]Manzanares M,Fbrega C,OssJ O,et al.Engineering the TiO_2,outermost layers using magnesium for carbon dioxide photoreduction[J].Applied Catalysis B,2014,150-151(18):57-62.
[25]Choi K M,Kim D,Rungtaweevoranit B,et al.Plasmon-enhanced photocatalytic CO_2 conversion within metal-organic frameworks under visible light[J].Journal of America Chemistry Society,2017,139(1):356-362.