共查询到20条相似文献，搜索用时 78 毫秒
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以正丁胺为模板剂合成了ZSM-5分子筛催化剂,并对模板剂对分子筛晶粒大小分布的影响进行了研究;对合成的ZSM-5分子筛催化剂用X粉末射线衍射仪进行了晶相分析,用AA粒度分析仪进行了晶体粒度分析.结果表明用该法合成的ZSM-5分子筛催化剂结晶度、纯度高、形貌规整,且有效地降低了工艺条件和合成时间. 相似文献
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介绍了M41S中孔分子筛材料的合成过程以及表面活性剂模板法合成中孔分子筛的影响因素,总的来说,它的合成与反应原料、模板剂、合成温度、酸碱度、模板剂与SO2前体摩尔浓度之比的选择有密切关系. 相似文献
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正十二烷在分子筛催化剂上的反应研究 总被引：2，自引：0，他引：2
采用正十二烷为原料,分剐用己二胺、二正丙胺和四乙基氢氧化铵为模板剂合成了ZSM-22、SAPO-11和β3种分子筛,进而制备了分别含有上述分子筛的催化剂,并对这些催化剂进行表征和评价。结果表明,酸量决定催化剂的活性,而酸强度分布与产品分布密切相关,相近酸分布的催化剂具有接近的产品分布。 相似文献
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以廉价的工业废弃物粉煤灰作为初始原料,四丙基氢氧化铵（TPAOH）为模板剂,分别采用两种合成方案制备出微孔分子筛ZSM-5样品。该法相较传统水热法,原料价廉易得,制备工艺简单。通过XRD、SEM、TR等手段对样品进行表征,发现两种方案均合成出了较高质量的ZSM-5,但形貌分别为薄片型和长六方体型。最后考察了其对水中Cr（Ⅵ）离子的吸附性能,结果表明合成的ZSM-5型样品对Cr（Ⅵ）离子有较好的吸附性能。 相似文献
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FeAlPO-11分子筛的合成及表征 总被引：1，自引：0，他引：1
以二正丙胺(DPA)为模板剂,利用水热法合成了FeAlPO-11分子筛,对合成的样品进行了XRD、FTIR、UV、TG、DTA和SEM表征.XRD、FTIR及UV分析结果表明样品具有AlPO-11分子筛的结构,且Fe元素已进入到分子筛骨架. 相似文献
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《西安文理学院学报》2020,(2)
对近几年SSZ-13分子筛合成时模板剂、晶种、矿化剂、晶化原料等因素的影响进行了综述,介绍了凝胶法、干凝胶法、β型分子筛转化法、β和L型沸石分子筛之间的转化以及有机季铵碱四甲基氢氧化铵的使用等新型合成方法,列举了近几年SSZ-13分子筛主要的工业应用进展,并对SSZ-13的发展前景进行了展望. 相似文献
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综述了不同类型的有机胺在合成中孔分子筛中所起的作用和对分子筛性能的影响.沸石分子筛合成过程中,有机胺作为模板剂,可以有效地起到支撑沸石骨架、平衡电荷、增加孔容以及提高硅铝比的作用,但也应该考虑到有机胺的用量对分子筛焙烧脱胺和霍夫曼降解的影响. 相似文献
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采用有机小分子三乙醇胺同时作为水解抑制剂和模板剂,丙醇锆作为前驱物,通过溶凝胶工艺合成了二氧化锆介孔分子筛.利用X射线粉末衍射、低温N2吸-脱附法等表征手段,考察了晶化温度对二氧化锆介孔分子筛介观结构的影响. 相似文献
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以正硅酸四乙酯（TEOS）为硅源,十二胺（DDA）为模板剂制备HMS介孔分子筛,考察了模板剂脱除方法对HMS介孔分子筛结构的影响.结果表明：采用高温焙烧法脱除模板剂简单易行,但对分子筛结构有部分破坏作用;而采用溶剂萃取法脱除模板剂,介孔结构的有序性能得到很好的保持,但是周期较长.最后针对两种方法的优缺点,提出了各自的改进方法. 相似文献
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烯烃芳构化是催化裂化(FCC)汽油改质、高辛烷值燃料油的重要手段.采用预制晶种法合成了纳米ZSM-5分子筛,并采用液相沉积法制备了Ga沉积量不同的系列改性纳米ZSM-5分子筛,分别采用XRD、N2物理吸附、SEM、TEM、XPS、H2-TPR和Py-IR等表征手段对改性前后的纳米ZSM-5分子筛的形貌、织构特性和酸性等进行了表征,并采用固定床微型反应器对其催化己烯-1芳构化反应性能进行了评价,研究了Ga改性对纳米ZSM-5分子筛的物理化学性质及催化性能的影响规律.Ga液相沉积改性的ZSM-5分子筛中Ga物种主要以Ga2 O3和提供强Lewis酸性位的GaO+形式存在,由于Ga改性提高了分子筛的脱氢反应活性,己烯-1芳构化反应的芳烃选择性显著提高,以Ga沉积量适宜的Ga4.2/NZ5为催化剂时,芳烃选择性高达55.4％. 相似文献
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《海外英语》2007,(5):10-11
Many college freshmen arrive woefully unprepared to do college work, and as disadvantaged populations continue to grow, the share of the American work force that has made it through college is expected to plummet. Many experts blame that educational failure not just on high schools but also on colleges. School & College, a special report by The Chronicle, looks at efforts to fix the system. What reforms would better prepare students for college? What should schools and colleges be doing differently? How should state and federal officials help? 相似文献
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《海外英语》2007,(4):36
There are numbers of crossroads on our long and unpredictable life journey where we totally have no idea about which direction to choose. No matter what our decision is, we should not turn back, but face the music and go ahead instead. I am this kind of girl who always does try without regretting, one example is how I dealt with my love. 相似文献
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Migration occurs behind a variety of reasons and has a great effect on the whole world. People may migrate in order to improve their economic situation, or in order to escape civil strife, persecution, and environmental disasters. The impact of migration is complex, bringing both benefits anddisadvantages. This paper briefly talks about the causes of migration, the allocation of benefits, and the ways in which individual countries and the international community deal with this important subject. 相似文献
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Sister Carrie is one of the most controversial characters in American literature.Thought as a "fallen woman" firstly,she was defined as a "new woman" by some critics later. However, by digging into the motivaton behind the whole process of Carrie's "success", the relationship between Carrie and her creator (the author), the social conditions of then American, it can be found that Carrie has never been free-standing on her thought and she has never found her real-sdf even after becoming a famous actress. In a society dominated by mass consumerism Carrie is only an adherent of her own desires. She also is a representative of all those country girls flooded into cities, a symbol and a sacrifice of the urbanization of America in a time countryside was overcome by cities. 相似文献
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RUZBEHANI Mohsen 《重庆大学学报(英文版)》2004,3(1):20-25
1.IntroductionOne-cyclecontrolmethod,whichwasproposedaboutonedecadeago[1],hasbecomeanattractivemethodinspecialfieldssuchaspowerfactorcorrection[2-6],switchingamplifiers[7,8],etc.Themainideaofthiscontrollerisbasedonintegrationofdiodevoltageinone-cycleandforcesittobeexactlyequaltothereferencevalue.Themainadvantageofthiscontrollerisitsrealtimeabilitytorejectthevariationofinputvoltage[1].Despitethisgreatability,ithasnogoodperformancesinrejectingofloaddisturbanceandfollowingreferencecommands.Espec… 相似文献
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唐芳 《读与写:教育教学刊》2008,5(6)
During interview with English majors, it was found that a majority of students expressed disappointment with their experience of English literature classes. Students' dislike of learning English literature appears to be the major problem of teaching English literature in China. Reader response approach is a good way to solve this problem. In this paper, I explain the rationale behind the reader response approach, such as its origin, definition, features, assumptions, and strategies. Then I illustrate how reader response approach works as a teaching strategy by presenting several teaching models. At last I evaluate its usefuiness for teachers and present the advantages of reader response approach in Chinese context. 相似文献