【作者】 马宏卿；

【导师】 沈伯雄；

【作者基本信息】 南开大学 ， 环境工程， 2012， 博士

【摘要】 具有良好经济性和应用前景的低温氨选择性催化还原（NH₃SelectiveCatalytic Reduction, NH₃-SCR）脱硝技术已经成为烟气脱硝研究领域的重点。为开发低温下高效经济的催化剂，本文创新性地将锰（MnO_x）基氧化物负载在柱撑粘土（Pilared Intelayered Clays）上，并用于低温SCR脱硝。论文主要从MnO_x/Ti-PILC的制备及活性、脱硝性能的改进提高（从活性组分以及柱撑元素两方面）开展研究；其中对低温SCR反应动力学、催化剂抗SO₂性及失活机理也进行了探讨。并通过N2吸附/脱附、XRD、FT-IR、TG、NH₃-TPD、H₂-TPR、XPS等多种表征手段探索催化剂表面物理性质与活性之间的关系。论文主要获得以下结论：1.通过比较发现，Ti-PILC载体的制备参数、MnO_x负载量以及催化剂煅烧温度等对MnO_x/Ti-PILC的活性存在重要影响。通过优化研究，在Ti/clay为15mmol/g、H/Ti为1.2、1%的粘土悬浮液浓度、1:1（质量比）的水和丙酮作为溶剂，在500℃以下热处理后，可以得到适宜载体Ti-PILC。MnO_x/Ti-PILC的最佳负载量为10%，300℃下煅烧后，催化剂展现出最高的脱硝效率。其脱硝活性和MnO_x/Al₂O₃（γ-Al₂O₃）相当，且优于MnO_x/TiO2（P25），在65000h-1下仍保持较高的脱硝活性，180℃下，NO转化效率接近100%。催化剂具有较好的抗H₂O性，但抗SO₂特性有待进一步研究。2.系统地研究了掺杂型Mn-MOx/Ti-PILC的低温脱硝活性。掺杂元素M包括Bi、La、Fe、Sn、W、V、Ce，发现添加Ce、La对脱硝活性促进明显。Ce、La的添加存在一个最佳值。在最佳的Ce添加量下，Mn-CeO_x/Ti-PILC氧化还原性质最强，表面化学吸附氧浓度较高；在适量的La添加后，Mn-LaO_x/Ti-PILC氧化还原能力也明显增强，同时表面酸性改善，催化剂活性明显提高。Ce、La的添加提高了MnO_x/Ti-PILC抗H₂O和SO₂的能力。比较研究了不同的钛前驱物（方法）对Mn-CeO_x/Ti-PILCs的性能影响，发现以TiOSO₄为钛源通过沉淀反胶溶法得到的Ti-PILC负载Mn-CeO_x后，其活性优于Ti（OC₄H₉）₄溶胶法和TiCl₄酸解法得到的Ti-PILCs负载型的催化剂。这可能源与其较高的表面酸性、独特的孔结构、其粘土层外的TiO2也是可能的有利因素。这些均与其较好的交联柱撑效果有关。200℃下，此催化剂展现出一定的抗低浓度SO₂性能，在200ppmSO₂作用下，则迅速失活。以Mn-CeO_x/Ti-PILC催化剂为研究对象，通过N2吸附/脱附、XRD、FT-IR、TG、NH₃-TPD、H₂-TPR等表征手段，对比分析未中毒新鲜催化剂、SO₂中毒催化剂以及热处理后催化剂结构性质上的变化，探讨催化剂SO₂中毒机理。发现硫酸铵盐的沉积是催化剂失活的重要原因。以E-R、L-H机理为基础，建立动力学模型，并对100℃和200℃下试验数据进行分析，认为该催化剂的低温SCR反应趋于L-H机理。3.研究不同柱撑元素对负载型MnO_x基催化剂的低温脱硝活性影响，发现：对于MnO_x以及Mn-CeO_x双组份催化剂而言，Ti、Zr比Fe和Al作为氧化物柱时更有利。在此基础上，研究了两种共柱撑粘土负载型催化剂（MnO_x/Zr-Ce-PILC和Mn-CeO_x/Ti-Zr-PILC）的脱硝性能。研究表明Zr-Ce混合氧化物柱可以显著提高催化剂的比表面积、丰富其孔结构、改善MnO_x与载体的相互作用，提高其氧化还原性质以及表面酸性，MnO_x/Zr-Ce-PILC活性较单一柱撑的MnO_x/Zr-PILC和MnO_x/Ce-PILC更高。Zr-Ce混合柱撑在改善催化剂活性的同时，抗H₂O抗SO₂能力也得到一定改善。关于MnO_x/Ti-Zr-PILC的研究结果表明：对粘土进行有机改性可以促进Ti、Zr混合柱撑，从而进一步提高催化剂活性。更多还原

【Abstract】 The selective catalytic reduction of NOxwith NH₃（NH₃-SCR） as reductant atlow temperature has drawn much attraction as a promising technology to remove NOxfrom stationary sources. There is much interest in developing such a technologybecause of its low cost and industrial application demand. The key of the technologyis the catalyst. In this study, in order to develop economical catalysts with goodactivity, the MnO_x-based metal oxides has been supported over pillared interlayeredclays arosed from the economical and easy obtained clays, then the catalysts wereused for SCR of NO with NH₃at low temperature. The preparation and NH₃-SCRactiveity at low temperature of MnO_x/Ti-PILC, the promotion of its catalyticactivities （including the activie components and the pillars） were studed. The reactionkinetics and SO₂posioning mechanism have been systermaticly investigated. Besides,N2absorption/desorption, XRD, FT-IR, TG, NH₃-TPD, H₂-TPR, XPS characterisionmethods were also used to study the property-activity relationship of the catalysts.1. It was found that preparation factors of Ti-PILC（including Ti/clay, H/clay, thepillaring temperature, solvent, concentration of the clays and the thermal treatmenttemperature）, the MnO_xloadings and the cacinating temperatures all had greatinfluence on the SCR activity of MnO_x/Ti-PILC. Under the conditions of Ti/clay of15mmol/g, H/Ti of1.2,1:1weight ratio of H₂O and actone,1%clay suspention andthermal-treated at500℃, proper Ti-PILC support could be obtained for MnO_x,MnO_x/Ti-PILC with10%MnO_xloadings and cacainated at300℃exhibited superioractivity which was better than MnO_x/TiO2（P25）, even at high space velocity of65000h-1, nearly100%NO conversion cold be obtained at180℃. This catalystshowed good resistance to H₂O, however, its resistance ability to SO₂need to befurther studied.2. For the study of the active componts, different kinds of metal （M=Bi、La、Fe、Sn、W、V、Ce） has been doped to MnO_x/Ti-PILC to investigate their effect on theactivity, the results showed that both Ce and La were very helpful for the enhancement of the activity in absence of H₂O and SO₂. For the addition of Ce andLa, there was a best doped amout. the resultant Mn-CeO_x/Ti-PILC was enhanced inredox properties and surface ative absorbed O; Mn-LaO_x/Ti-PILC was also promotedin redox charactors and surface acidity concentration. These two catalysts displayedhiger activity than MnO_x/Ti-PILC, besids, the resistance to SO₂and H₂O was alsoheightened.It has been found that the preparation method of Ti-PILCs can influence the lowtemperature-SCR activity of Mn-CeO_x/Ti-PILCs, the catasyt with titania formTiOSO₄（Mn-CeO_x/Ti-PILC（S）） rewealed much higher activity compared to thoseform both Ti（OC₄H₉）₄and TiCl₄（Mn-CeO_x/Ti-PILC（O） and Mn-CeO_x/Ti-PILC（Cl））,due to its higher acidity concentration, extra-lattice TiO2, along with the large surfacearea and pore volume, all of which could be attributed to the effective pillaringprocess. Mn-CeO_x/Ti-PILC（S） could keep its high activity in presence of low amoutof SO₂（100ppm） at200℃, while deactived quickly when200ppm SO₂wasintroduced to the gas.In order to study the SO₂deactivation machanism on Mn-CeO_x/Ti-PILC, N2absorption/desorption、XRD、FT-IR、TG、NH₃-TPD、H₂-TPR methods were usedto investigeate and compare samples before/after SO₂posioned and heat-regenerated.It was assumed that the sulfates saltes deposited over the catalysts account for thedeactivation. Based on the experimental data at100℃and200℃, the kineticsexperiment was carried with the E-R and L-H mechanism, the results showed that theSCR tend to follow the L-H mechanism under the conditions in this study.3. Impacts of various pillars were also studied, the results displayed that thekinds of pillars had great influence on the activity of PILC supported MnO_xandMn-CeO_xcatalysts, Ti and Zr tend to be better for the activity than Fe and Al. On thebasis of the results, two MnO_xbased catalysts supported over PILC with mixedpillars（MnO_x/Zr-Ce-PILC and Mn-CeO_x/Ti-Zr-PILC） has been investigated. Theresults showed that the simple one-step method to introduce Zr and Ce pillars intoclays proved sucssesful to enhance the surface area and the pores, strengthen theintereaction between MnO_xand the support and improve the redox properties, thusthe activity was greatly promoted even in presence of H₂O and SO₂. For Mn-CeO_x/Ti-Zr-PILC catalysts, it could be concluded that organ-modification of theclays could contribute to better the pillaring process with Ti-Zr mixed pillars and thenenhanced the SCR activity of supported Mn-CeO_xcatalysts.更多还原