【作者】 李爱英；

【导师】 马智；

【作者基本信息】 天津大学 ， 工业催化， 2006， 硕士

【摘要】 本课题主要研究了酸碱改性方法对内蒙古煤系硬质高岭土（内蒙土）的结构和性能的影响规律。在酸改性过程中,重点对比分析了内蒙土和苏州土结构和性能变化趋势的差别。制备不同n（SiO₂）/n（Al₂O₃）酸改性土,并将酸改性土与一定量高岭土原土及PREHY分子筛以半合成方法合成FCC催化剂。利用BET方法测试了酸改性土的比孔容,比表面积和孔径分布的变化,并分别对酸改性土和FCC催化剂进行了吡啶-TPD表征和裂化活性测试。实验表明:当n（SiO₂）/n（Al₂O₃）<20时,随着n（SiO₂）/n（Al₂O₃）的增加,两种土的孔容和比表面积,表面酸量和裂化活性都显著增加;当n（SiO₂）/n（Al₂O₃）>40时,两种高岭土孔容、比表面积、表面酸量和裂化活性数值都趋于稳定,孔径主要集中在3～10nm之间;相同n（SiO₂）/n（Al₂O₃）时,内蒙土的酸强度高于苏州土,裂化性能也优于苏州土;FCC催化剂的表面酸性和裂化活性与其所含的高岭土的n（SiO₂）/n（Al₂O₃）有关;增加FCC催化剂中酸处理土含量可以增加FCC催化剂裂化性能。在碱改性的过程中,利用NaOH溶液对内蒙土进行碱改性,制备不同n（SiO₂）/n（Al₂O₃）的碱改性土,对其进行了XRD,BET,吡啶-TPD表征和裂化活性测试。结果表明:随着n（SiO₂）/n（Al₂O₃）的减小,孔径分布宽化,比孔体积减小,比表面积、表面酸性和裂化活性均增加。利用²⁹Si和²⁷Al MAS NMR研究了内蒙土煅烧和酸碱改性过程中Si、Al原子环境的变化,并比较了酸、碱改性内蒙土的性能差别:不同形态的铝原子酸碱反应活性不同,酸活性顺序为Al（V）>Al（VI）>Al（IV）,碱活性顺序为Al（VI） >Al（IV）;酸碱改性都可以使高岭土获得2～8nm的孔径分布;酸改性土的酸性位数量和强度均高于碱改性土;碱改性高岭土的裂化性能优于酸改性土。更多还原

【Abstract】 The structure and characteristic of acid and alkali modified kaolin of coal measures of Inner Mongolia was studied in this paper. The kaolin of Inner Mongolia and Suzhou with different molar ratio of n（SiO₂）/n（Al₂O₃） has been prepared by the mean of acid modification. The effect of the ratio of n（SiO₂）/n（Al₂O₃） on the kaolin performance, including BET surface area, pore distribution, pore volume, surface acidity, amount of acid sites and cracking capability, was examined by pyridine-TPD, nitrogen adsorption and the test of activity cracking. The results indicated that pore volume, BET surface area, surface acidity and cracking activity of the two kinds of kaolins increased obviously with the increase of the ratio of n（SiO₂）/n（Al₂O₃） when the ratio was always smaller than 20. After the ratio of n（SiO₂）/n（Al₂O₃） became more than 40, the nature of two kinds of kaolin went to stable. The pore radium ranged from 3nm to 10 nm. The results also showed that the acid intensity and cracking performance of Inner Mongolia Kaolin are all better than Suzhou Kaolin. Furthermore, FCC catalysts were synthesized of acid-treated kaolin, certain amount of kaolin and PREHY zeolite. We examined the effect of the ratio of n（SiO₂）/n（Al₂O₃）and the quantum of acid-treated kaolin on the activity of FCC catalysts. The results showed that surface acidity and cracking performance of FCC catalysts were related to the ratio of n（SiO₂）/n（Al₂O₃） of kaolin contained in the catalysts and that the amount of acid-treated kaolin improved the cracking performance of FCC catalysts. We prepared alkali-treated kaolin of Inner Mongolia with different molar ratio of n（SiO₂）/n（Al₂O₃）. The effect of the ratio of n（SiO₂）/n（Al₂O₃） on the kaolin performance, including structure, physical nature, surface acidity, acid-quantum and cracking capability, was examined by XRD, Nitrogen adsorption, pyridine-TPD, and the test of cracking activity. The results indicated that the distribution of pore radium broadened and pore volume increased with the increase of the ratio of n（SiO₂）/n（Al₂O₃）. Contemporarily, BET surface area, surface acidity and cracking activity raised up.The environment change of Si and Al were studied by MAS NMR when kaolin were calcined and treated by acid or alkali. The results showed that the activity was different because of different modality of Al atom. The order of acid and alkali更多还原