【作者】 温斌；

【导师】 何鸣元；

【作者基本信息】 石油化工科学研究院 ， 有机化工， 2000， 博士

【摘要】 FCC（流化催化裂化）是炼厂生产汽油的主要方法之一。但是在FCC再生器烟气中含有大量的NOx、SOx、CO等环境不友好气体。据统计，FCC过程中SOx和NOx的排放分别占空气中总排放的6％-7％和10％。由于FCC再生器中特殊的物理化学环境（高温、多种气体及多个反应共存），到目前为止，没有任何一种催化剂能有效的同时脱除这几种污染物，同时，针对这一课题所进行的理论研究工作也很少。本论文中首次提出将一种含有过渡金属和稀土金属，由共沉淀的层状柱撑类水滑石物质和稀土化合物的混合物经高温热活化得到的复合氧化物催化剂（铜铈类催化剂）用于同时脱除FCC再生器烟气中的NOX、CO、SOx。此类催化剂具有高的NO和CO反应活性、优异的水热稳定性以及抗硫氧化物毒化的性能，同时能促进SO2向SO3的转化、有效捕集SOx且能高效再生。利用多种表征手段对其结构进行了详细考察，同时利用程序升温（TPD、TPR、TPSR）、多分子探针原位红外表征以及XPS技术对各气体组分在催化剂表面上的相互作用、催化剂活性组分之间的协同效应、催化反应机理进行了系统研究。研究结果表明： 1．共沉淀过程中，铜离子易取代部分镁离子进入水滑石结构形成类水滑石化合物，而铈离子在共沉淀过程中以氢氧化亚铈的形式沉淀，在干燥过程中形成二氧化铈。热活化时，随着活化温度的升高，类水滑石结构逐渐被破坏，铜类催化剂中出现氧化铜、氧化镁或尖晶石晶相。但铈的引入会使氧化铜分散度增大，同时抑制尖晶石相的生成。铜类催化剂中氧化铜的还原峰温比纯氧化铜还原峰温低，催化体系中引入铈后（铜铈类催化剂），还原峰温进一步降低，峰形也发生较大的变化。这说明铜铈之间发生了很强的相互作用。 2．XPS分析表明，铜类催化剂中的铜主要是以Cu²⁺的形式存在；铜铈类催化剂中，部分铜离子进入了CeO2的晶格结构，以Cu²⁺的形式存在，同时在催化剂表面产生了大量的氧空位，即铜铈之间存在着协同效应。 石油化工科学研究院博士学位论文，2000 3．对于NO和CO反应，铜钵类催化剂的反应活性高于铜类催化剂和饰类催化剂。水热处理使催化剂的低温活性降低，高温活性不受影响。体系中少量氧气的存在有利于铜钵类催化剂低温NO和CO反应活性的提高，但对铜类催化剂和钵类催化剂的低温活性不利。体系中引入水蒸气时，由于铜饰类催化剂高的水气反应活性，其DeNOx和DeCO活性提高2 而在铜类催化剂和钵类催化剂上，水蒸气使催化剂的低温NO和CO反应活性降低，高温时则有利于NO和CO的转化。 4．SO。的存在对铜钵类催化剂的DeNOx活性没有影响，而使铜类催化剂和钵类催化剂很快失活。同时，SOZ的引入使钵类催化剂对CO和OZ、CO和HZO的反应均出现失活；使铜类催化剂对Co和HZo的反应失活，而对CO和O。的反应没有影响；使铜钵类催化剂对CO和HZO的反应活性略有降低，但对CO和OZ的反应没有不利影响。 5．催化剂的NO和CO反应活性受 COMO比值的影响，比值降低，催化剂的活性温度窗口向高温方向移动Z三类催化剂中铜饰类催化剂的活性受CO／NO比值的影响程度最小。催化剂本身不具有NO分解能力，但经过一定温度下 HZ还原后会产生一定的活性；经过同样条件处理，铜钵类催化剂的NO分解活性最高。 6．在NO(0刀6％卜CO(1．4％p。（0．5％卜HZO（1刀％卜SO。（0刀5％）＋Ar这一还原气氛中，一部分SOZ被还原为单质硫，一部分以硫酸盐的形式化学吸附于催化剂上，其余的则以 SOZ的形式排出，三类催化剂上的SOZ的脱除率均在80％以上。在氧化气氛中u L高温时三类催化剂的SOx吸附容量均显著高于工业硫转移剂SOXGT。 7．三类催化剂中，铜袜类催化剂 CuCe＊）P的 NO室温吸附量最大，其表面存在三种NO吸附中心。同时，CuCe＊）P表面存在着强的CO吸附中心。在NO、CO、OZ共存的气氛中CO和OZ的反应优先于NO和CO的反应发生，铜柿类催化剂对于这丙个反应的活性均明显高于其它两类催化剂。在NO＋C趴O。（0．5％）＋SO。气氛中程序升温时，SQ。在催化剂上发生吸附以 二且 摘 要 及相应的分解和还原，同时使铜类催化剂和饰类催化剂的DeNOx活性丧失。 但铜钵类催化剂在高温时仍具有DeNOx性能。这体现了铜钵之间的协同作 用。同时，铜钵类催化剂对CO和SOZ的反应也有较高的活性。 8．红外光谱表征发现，Cu＋和“共存时，CO优先选择吸附于 Cu＋上， 在cuz＋上吸附很弱；吸附温度升高，Co吸收峰谱带向低波数位移；由于 CuCe(si中存在较多的CU＋，CO在其表面吸附时的吸收峰位置较在Cu(加 上时偏低。与CO吸附相反，NO在y上吸附很强，而在比上吸附很弱； NO能够吸附在 Ce(Zi的表面氧空位上，但表现不出相应的红外波谱特征。 与NO和CO单独吸附时相比，NO和CO共吸附时，两者的吸收峰强度都 有所减?更多还原

【Abstract】 The Fluid Catalytic Cracking (FCC) is the major gasoline-producing process in refinery. Considerable amounts of harmful gases (SOx, NOx, CO) are generated with the FCC operations. In the United States, FCC operations are estimated to emit 6%-7% of the total SOx emissions and 10% of the NOx emissions. Because of the special physico-chemical atmosphere in the FCC regenerator, the catalysts which can be used for effectively removing these gases simultaneously from the flue gas have not been developed up to now.In our research, we have developed a kind of new rare-earth-promoted mult-component catalysts (CuCeMgAl(O)) using coprecipitation method which exhibit excellent performance for simultaneous removal of NOx, SOx, CO from the NO + SO2 + CO + 02 + H20 reaction system. This kind of catalysts have following properties: high activity for NO + CO reaction with the excellent resistance to 502 poisoning; excellent hydrothermal and thermal stability; high catalytic activity for the reaction of SO2 and 02 and effective capturing capacity for SOx under regenerator conditions. Many analyzing techniques including TPD, TPR, TPSR, in-situ JR and XPS were employed to characterize the catalysts and to elucidate the reaction mechanism. The results are summarized as follows:1.Mg2 in the hydrotalcite can be substituted partially by Cu2 in the course of coprecipitation, and Ce4~ ions exist in the form of CeO2, it can not enter into the structure of hydrotalcite. With the increase of activation temperature, the structure of hydrotalcite is destroyed gradually and CuO, MgO or spinel phase can be detected by XRD. The addition of cerium can inhibit the formation of spinel phase and make the CuO disperse well. The reduction temperature of copper ion in the CuCeMgA1(O) is lower than that in the CuMgAJ(O), which indicates the synergic effect between copper ion and cerium ion.2.XPS analysis shows that most of copper ions in the CuMgAl(O) arewhereas considerable amounts of Cu~ and oxygen vacancies exist in the CuCeMgAl(0) which are produced by the partial substitution of Ce4~ in the CeO2 by Cut.3.For the reduction of NO by CO. the activity of CuCeMgAl(0) is higher than that of CuMgAJ(O) and CeMgAl(O); the presence of a small amount of oxygen and I~20 rnthe reaction system increases the activity of CuCeMgAJ(0); the reactions of NQ+C0, CO+02 on CuCeMgAl(O) are not affected by the presence of 502 while the activity for CO+H20 reaction decreases slightly; the CuMgA1(O) is deactivated for NO+C0, CO+H20 reactions in the presence of SO2, whereas the activities of CeMgAl(O) for all these three reactions (NO+CO, CO+02, CO+H20) were inhibited by addition of SO2 into reaction system.4.In the reaction system of NO(0.06%) + C0(l.4%) + 02(0.5%) + H20(l.0%) +S02(0.05%), one part of 502 is reduced to 5, one part is adsorbed on the catalysts in theform of sulfate, and the rest is emitted; the SO2 removal ratio on the CuCeMgA1(O) IS Ca.88%; in the oxidizing atmosphere (502±02), the SOx adsorption capacity onCuCeMgAl(0) is much higher than that of the industrialized DeSOx catalyst SOXGT.5.Among the three catalysts of CuCeMgA1(O), CuMgAl(O) and CeMgAJ(O), CuCeMgA1(O) has the highest NO adsorption capacity at room temperature. There are three kind of adsorption cites in the surface of CuCeMgAl(0); in the NO+CO+02 system, the reaction of CO+02 occurs before CO+NO reaction, meanwhile, CuCeMgAI(O) has high activity for the reaction of CO and SO2.6.In-situ FT-JR study reveals that CO is selectively adsorbed on the Cu4 sites and2+NO is selectively adsorbed on the Cu sites when Cu4 and Cu24 coexists on the surface;with the increase of adsorption temperature, CO-Cu4 bands shift to lower frequencies; NO can be adsorbed on the oxygen vacancies in the surface of CeO2, but no JR characterizations take on; when NO and CO are coadsorbed on the CuCeMgA.l(O). the intensities of Cu’-CO bands and Cu2~-NO bands are both decreased considerably; with the increase of temperature, NO更多还原