【作者】 韩静；

【导师】 赵毅；

【作者基本信息】 华北电力大学（河北） ， 热能工程， 2009， 博士

【摘要】 本文以活性炭纤维为载体制备了负载型纳米TiO2光催化剂,利用自制的光催化反应器,进行了烟气同时脱硫脱硝的实验研究。系统的考察了各种因素对光催化氧化烟气同时脱硫脱硝的影响,提出了基于可见光催化氧化烟气同时脱硫脱硝的方法。通过烟气脱硫脱硝产物形态和微区形貌分析,探讨了TiO2光催化烟气同时脱硫脱硝的机理。同时,利用光催化反应条件,建立了脱硫脱硝效率的预测模型。利用分步水解法制备了混晶型纳米TiO2催化剂,溶胶凝胶法制备了锐钛矿型纳米TiO2催化剂,同时采用浸渍法制备了负载型TiO2/ACF光催化剂。扫描电镜(SEM )、透射电镜(TEM )和X射线衍射(XRD )表征结果显示,混晶型和锐钛矿型纳米TiO2催化剂的平均粒径分别为10nm和22.8nm。以甲基橙为目标降解物,考察了混晶型纳米TiO2催化剂的光催化活性,为烟气同时脱硫脱硝的实验研究提供了基础。无光照条件下,纳米TiO2光催化剂对SO2和NOx有吸附作用,但无光催化氧化反应发生,光照是SO2和NOx发生光催化反应的必要条件。烟气含氧量、烟气湿度、反应温度、SO2和NOx初始浓度等因素对SO2和NOx光催化反应有显著影响。光催化反应过程中SO2和NOx的脱除以催化氧化过程占主导地位。可见光照射,最佳实验条件下,锐钛矿型纳米TiO2催化剂对SO2脱除效率可达88.4%,NOX最高脱除效率达到40%,混晶型纳米TiO2催化剂的脱硫脱硝效率可分别进一步提高到97%和51.2%,表明混晶型纳米TiO2催化剂的催化活性高于锐钛矿型TiO2催化剂的催化活性。一定浓度范围内,SO2和NOx的光催化脱除存在相互促进作用。SO2浓度在800～2000 mg/m3的范围内,随着SO2浓度的增加,对脱硝有促进作用,在SO2为2000 mg/m3时,对脱硝促进最显著。NOx浓度在600～1000 mg/m3的范围内,也可提高SO2的脱除效率。X射线能谱(EDS )、产物的化学分析、离子色谱(IC )及X射线衍射(XRD)分析结果表明,光催化脱硫脱硝产物为硫酸盐和硝酸盐,SO2和NOx光催化反应脱除的机理主要为光催化氧化反应。基于SPSS多元线性回归和人工神经网络,建立了光催化脱硫脱硝效率预测模型,预测的光催化脱硫脱硝效率与实测光催化脱硫脱硝效率相吻合,表明模型预测精度较高。更多还原

【Abstract】 In this experriment, supported TiO2 photocatalyst was prepared onto activated carbon fiber, and the photocatalytic degradation experiment was carried out on the self-made photoreactor at high concentration level. Many influencing factors were investigated in detail. A new approach and principle of SO2 and NOx simultaneous removal from flue gas was presented by TiO2 potocatalyst based on visible light technology.The chemical and micro-structure analysis on the products of the desulfurization and denitrification reactions were analysed, the mechanism of simultaneous desulfurization and denitrification by photocatalytic oxidation was deduced. On the basis of the experimental reaction condition, the desulfurization model and the denitrification model were proposed.Mixing nano-crystalline TiO2 photocatalyst was prepared by twice hydrolysis method, and nano-anatase TiO2 catalyst was prepared by sol-gel method. Supported TiO2 /ACF photocatalyst was prepared by dip-coating method.The performance of TiO2 photocatalyst was characterized by SEM, TEM and XRD. The nanometer TiO2 existed and the particle size of mixing nano-crystalline and nano-anatase TiO2 photocatalyst were 10nm and 22.8nm, respectively.The photocatalytic activity of mixing nano-crystalline TiO2 photocatalyst was evaluated by degradation of methyl orange.The results provided prerequisite for the next application of simultaneous desulfurization and denitrification of flue gas.SO2 and NOx could be adsorbed by TiO2 photocatalyst without visible light, and the photolysis and oxidation of couldnot occured by TiO2 photocatalyst. Visible light irradiation plays a vital role in photocatalytic desulfurization and denitrification.Presence of O2, humidity of flue gas, temperature and initial concentration of SO2 and NOx were most essential factors to photocatalytic oxidiation of SO2 and NOx. The photocatalytic oxidation was primary in the removal process of SO2 and NOx. Under the optimum experimental conditions,the removal efficiency of 88.4% for SO2 and of 40% for NOx with nano-anatase TiO2 photocatalyst were obtained respectively. And the higher removal efficiency of 97% for SO2 and of 51.2% for NOx with mixing nano-crystalline TiO2 photocatalyst were obtained respectively.The results showed that under the visible light irradiation, the activity of mixing nano-crystalline TiO2 photocatalyst was higher than that of nano-anatase TiO2 photocatalyst.In certain concentration range, the removal of SO2 and NOx had a promotion for each other. During the concentration of SO2 among 800~2000 mg/m3, the removal of NOx was promoted gradually with the concentration of SO2 increased. The highest removal efficiency of NOx was obtained at 2000 mg/m3 of SO2. During the concentration of NOx among 600~1000 mg/m3, the removal efficiency of SO2 was increased gradually with the concentration of NOx increased.X-ray spectroscopy (EDS), a product of the chemical analysis, ion chromatography (IC) and X-ray diffraction (XRD) showed that the photocatalytic simultaneous desulfurization and denitrification products were sulfate and nitrate, the removal photocatalytic reaction mechanism of SO2 and NOx was the photocatalytic oxidation reaction,Based on SPSS multiple linear regression models and BP nerve network model, the predict model of the simultaneous desulfurization and denitrification photocatalytic efficiency was been done.The simulated results were approximately in accordance with the practical case and reached a high accuracy.更多还原