毕业论文-锰氧化物合成及催化酯化反应的研究.doc

锰氧化物合成及催化酯化反应的研究摘 要：本论文通过对一系列纳米结构锰氧化物的制备及对其性质的表征，旨在寻找具有特殊性能的新型催化剂及其制备方法。实验利用Zn(Ac)2 和Mn(Ac)2为原料，H2O2为氧化剂在NaOH溶液中共沉淀制备ZnMn2O4。基于这种方法，改变反应条件（反应物摩尔配比，氧化剂用量，陈化时间，反应温度等）最终在常温常压的温和条件下得到了单一晶形的均匀纳米颗粒，粒径在10nm 20nm。同时也利用水热法制得了-MnO2纳米线，-MnO2纳米颗粒。最后利用XRD，TEM对所制得的产品进行表征。 利用在不同条件下制得的一系列锰的氧化物催化合成乙酸异戊酯，分别得到其酯化率为：-MnO2纳米线：80%左右；-MnO2纳米颗粒：86%左右；ZnMn2O4（煅烧200500）：88%94%。关键词：纳米结构锰氧化物；纳米颗粒；水热法；乙酸异戊酯；酯化率Abstract: In order to look for the method of preparing new pattern of catalyst，which had some special performances, we prepared a chain of nanostructured manganese oxides and attributed their behavior in this articles. Zn(Ac)2 and Mn(Ac)2 were used to prepare ZnMn2O4 in the NaOH solution by the oxidizer of H2O2. Based on such a method, we transferred reaction conditions, such as the mol matching of the reactant, oxidizer dosage, ageing time , reaction temperature and so on. Ultimately, we had received unique crystal form and uniform nanoparticles, their diameter is about 10nm 20nm. Meanwhile, -MnO2 nanolines and - MnO2 nanoparticles were synthesized by the method of hydrothermal synthesis. Finally，XRD and TEM techniques were used to characterize the as-prepared products. Then we synthesized isoamyl acetate by using manganic oxide that been synthesized in different condition. The esterification ratio was concluded that -MnO2 nanolines: about 80%, - MnO2 nanoparticles: about 86%, ZnMn2O4 (furnacing200 500)：88%94%.Keywords: nanostructured manganese oxides; nanoparticles; hydrothermal synthesis; isoamyl acetate; esterification ratio - 2 -1 引言 纳米技术的发展为新材料开发提供了一条全新的途径，并注入了新的活力，必将推动信息、能源、环境、生物、农业、国防等领域的技术创新，成为继工业革命以来，三次主导技术引发的产业革命以后的第四次浪潮的基础。纳米技术既包含了丰富的科学内涵，又给人们提供了广阔的创新空间，从而成为物理，化学，材料科学，生命科学以及信息科学发展的新领地。人们正在利用纳米技术在纳米尺度范围内认识和改造自然，通过直接操纵和安排原子，分子而创造新材料。纳米技术的出现标志着人类科学技术已进入了一个新的时代纳米科技时代。纳米是一个长度单位（1nm=10-9m），纳米科学是研究纳米尺度范畴内（1100nm）原子，分子和其它类型物质运动的变化的科学。而纳米技术则是在纳米尺度范围内对原子，分子等进行操纵和加工的技术。纳米科学技术是一门多学科交叉的，基础研究和应用开发紧密联系的高新科学技术。它包括纳米材料学，纳米电子学，纳米机械加工学，纳米生物学，纳米化学，纳米力学，纳米物理学和纳米测量学等若干领域1。纳米材料因其体积效应和表面效应等在磁性、催化、光吸收、热阻和熔点等方面显示出特异的性质，因而受到人们的极大关注。纳米催化技术是非常重要的纳米技术的分支。在过去十年间纳米催化技术（主要是纳米粒子在催化反应中的应用）得到了迅速发展。这方面的研究工作集中在液相中的均相催化技术和负载于基底上纳米粒子的非均相催化技术。纳米粒子具有比相应的体相材料大得多的比表面积，因此更适于用作催化剂。1996年，报道合成了不同形貌的过渡金属纳米粒子，探索了它们在不同催化反应中的潜在应用2。最近的研究表明对于溶胶中的同一电子迁移反应，不同形貌的铂纳米粒子作为催化剂时表现出不同的活性3。这种由形貌决定的催化作用突出了纳米粒子作为催化剂的优势。显然这些处于纳米粒子棱角和边缘的表面原子不稳定，在化学反应中易于表现出催化作用，并且使粒子形貌发生改变4。1.1 纳米材料的特异性能（1）表面效应指的是纳米粒子的表面原子与总原子之比，随着粒径的变小而急剧后所引起的性质上的变化，由于其具有很高化学活性，常用于做催化剂、助剂环境敏感性物质等。（2）小尺寸效应在物质的颗粒减小到纳米尺度（ Zn2Mn4O8纳米粒子 Mn3O4纳米粒子a- MnO2纳米棒市售MnO2。如果没有催化剂存在（空白），酯化率很低。4.4.2 Zn2Mn4O8催化剂在不同温度下煅烧后对其催化性能的影响为了研究Zn2Mn4O8纳米粒子的催化性能，我们又利用在不同温度下煅烧所得到的Zn2Mn4O8（500以上得到纯态的ZnMn2O4）进行催化酯化反应，得到如下（图4-3）酯化率和煅烧温度之间的关系。样品在200有最高的催化酯化率。没有煅烧的样品比煅烧200的样品催化性能要差很多，我认为应该是在没有煅烧的样品中含有水分，而正是由于水分子的存在减小了催化剂和醇及酸的接触面因而导致催化效率下降；而在300之后的酯化率只所以降低的原因我认为可能是由于温度过高时，样品颗粒长大、聚集而使得其比表面积减小所致。图4.3 酯化率与煅烧温度间的关系5 结论与展望本文全面系统地介绍了纳米催化材料的特点，及其在主要的制备方法、有机合成领域的应用研究现状。特别是纳米结构锰氧化物在上述领域一直是研究的热点，目前仍然存在制备方法复杂、应用研究范围狭小等问题。在此基础上，本文只要研究制备锌锰复合氧化物纳米材料的新方法，并进一步研究了一系列纳米结构锰氧化物对合成乙酸异戊酯的催化性能，为其实际应用奠定了实验基础。（1）常温常压和水热法成功控制合成了纳米结构锌锰复合氧化物。利用醋酸锌（Zn(Ac)2 2H2O）和醋酸锰（Mn(Ac)24H2O）为原料，双氧水为氧化剂，改变各方面反应条件（反应物摩尔配比，氧化剂用量，陈化时间，反应温度等），最终在常温常压的温和条件下得到了单一晶形的均匀ZnMn2O4复合氧化物纳米颗粒17，其具有很好的催化酯化反应性能。本实验方法简单，条件温和，无须用到高温高压的装置，操作安全可靠，后处理只须在200的烘箱中烘烤几个小时就可以了。同时也利用水热法制得了-MnO2纳米线，对比了各种不同锰的氧化物的物理化学性质。（2）利用所制得的各种纳米结构锰氧化物对合成乙酸异戊酯酯化反应的催化活性进行实验。以所制备的纳米结构锰氧化物为催化剂，采用反应蒸馏技术进行了乙酸异戊酯的合成研究。实验发现，ZnMn2O4复合氧化物纳米颗粒对合成乙酸异戊酯酯化反应具有优良的催化活性。在相同反应条件下，它催化异戊醇的酯化率明显高于以a-MnO2纳米棒、- MnO2纳米颗粒和Mn3O4纳米粒子作为催化剂时的酯化率（催化乙酸异戊酯合成反应的最佳工艺条件为：酸醇摩尔比为1.5:1，催化剂量为反应物质量的0.2%，反应时间为210 min）。在此条件下以ZnMn2O4复合氧化物纳米颗粒作为酯化反应的催化剂时的反应酯化率高达96%，虽然发现在反应过程中有部分催化剂溶解或是反应而消失，但是通过计算，即使是所有的催化剂都形成了醋酸盐，其最佳酯化率仍然在95%以上，而且也很容易将其和所形成的酯分离开来。由于时间关系，没有对反应后的产物做进一步分析，虽然结果可能存在一定的误差，但是我觉得，这种催化剂还是很有研究价值的。谢辞本次论文是在杨则恒老师和张卫新老师的大力支持和细心指导下顺利完成的，在为期三个月的毕业设计中，因为杨则恒老师、张卫新老师对我的悉心教导，使我不仅在实验和理论知识方面有一定收获，也使我明白了在科学研究中不仅要有科学的方法，严密的思维，更要有端正的、实事求是的科研态度，在此向两位老师表示衷心的感谢!在实验过程中，唐述培老师和刘岸平老师在实验仪器及产物的测试方面给予了大力的支持，在此向两位老师表示感谢。另外，本次论文得到了本实验室的师兄，师姐及各位同学的无私帮助，借此机会一并向他们表示感谢！参考文献1 许并社.纳米材料及应用技术M.化学工业出版社,2004.1-3.2 Ahmadi T S,Wang Z L,Green T CJ. Science. 1996. 272.3 Narayanan R, El-Sayed A.J Nano. Lett., 2004.1343.4 Narayanan R, El-Sayed A. J. J. Phys Chem B, 2004.108.5 张全勤,张继文.纳米技术新进展M.国防工业出版社,2005.99.6 阎子峰.纳米催化技术M.化学工业出版社,2003.37.7 Zhang W X, Yang Z H, Liu Y. J J Cryst Growth, 2004, 263:394.8 Hong X L, Zhang G Y, Zhu Y YJ. Mater Res Bull, 2003, 38: 1695.9 Hill L I, Verbaere A, Guyomard D.J. J. Power Sources, 2003, 119-121: 226. 10 王占国. 纳米半导体材料的制备技术J. 微纳电子技术, 2002(1): 9-14.11 I. P. Parkin. Convenient, room-temperature, amine-assisted routes to metal sulfides, sele-nides and telluridesJ. Chem. Soc. 1997, 19: 3505-3508.12 赵立志. 纳米材料的应用J. 天津化工, 2003, 17(5): 39- 41.13 何顺爱，周双喜等.水热沉淀法制备ZnO纳米粉体J.桂林工学院学报，2004，24（1）: 80-84.14 常照荣，刘院英等.湿法制备纳米二氧化锰及其电化学性能的研究J.河南师范大学学报(自然科学版)，2006,34（l）: 77-79. 15 Jason P. Durand, Josanlet C. Villegas. Colloidal Manganese Oxide Precursor to Octahedral Layered,OL-3 MaterialsJ. Journal of Inorganic and Organometallic Polymers and Materials, 2007, 17(2): 460.16 Jijun Qiu , Zhengguo Jin, Zhifeng Liu.Fabrication of TiO2 nanotube film by well-aligned ZnO nanorod array filmand solgel processJ. Thin Solid Films 515 (2007) 28972902.17 李海霞，李大光等.纳米复合氧化物催化剂研究进展J.无机盐工业，2004,36（4）: 1-2.请您删除一下内容，O(_)O谢谢！Many people have the same mixed feelings when planning a trip during Golden Week. With heaps of time, the seven-day Chinese National Day holiday could be the best occasion to enjoy a destination. However, it can also be the easiest way to ruin how you feel about a place and you may become more fatigued after the holiday, due to battling the large crowds. During peak season, a dream about a place can turn to nightmare without careful planning, especially if you travel with children and older people. As most Chinese people will take the holiday to visit domestic tourist destinations, crowds and busy traffic are inevitable at most places. Also to be expected are increasing transport and accommodation prices, with the possibility that there will be no rooms available. It is also common that youllwait in the line for one hour to get a ticket, and another two hours at the site, to only see a tiny bit of the place due to the crowds. Last year, 428 million tourists traveled in China over the week-long holiday in October. Traveling during this period is a matter that needs thorough preparation. If you are short on time to plan the upcoming Golden Week it may not be a bad idea to avoid some of the most crowded places for now. There is always a place so fascinating that everyone yearns for. Arxan is a place like this. The beauty of Arxan is everlasting regardless of the changing of four seasons. Bestowed by nature, its spectacular seasonal landscape and mountains are just beyond word. Arxan is a crucial destination for the recommended travelling route, China Inner Mongolia Arxan Hailar Manzhouli. It is also the joint of the four prairies across the Sino-Mongolian border, where people gravitate towards the exotic atmosphere mixed with Chinese, Russian, and Mongolia elements. As a historic site for the Yitian Battle, Arxan still embodies the spirit of Genghis Khan. Walking into Arxan, you will be amazed by a kaleidoscope of gorgeous colors all the year round - the Spring azaleas blooming red in the snow, the Summer sea wavering blue in the breeze, the Autumn leaves painted in yellow covering volcanic traces, and the Winter woods shining white on the vast alpine snowscape. Hinggan League Arxan city is situated in the far eastern area of Inner Mongolia Autonomous Region. Its full name Haren Arxan means hot holy water in the Mongolian language. Arxan is a tourism city in the northern frontier with a blend of large forest, grand prairies, vast snowfield, heaven lake cluster, thermium, as well as volcanic cluster. It is a rare and unique ecotourism base filled with healthy sunshine, clean air and unspoiled green. Nestled close to the countrys largest virgin forest, and known for its spring and ecological environment, Arxan is marveled at by many tourists as the purest land on earth. You cannot miss out the Autumn of Arxan. It is definitely the best with brightly-colored scenery full of emotions. Autumn in the northern part of the country comes earlier than the South. A September rain followed by the footprints of Autumn brings more colors to the once emerald green mountain and blooming grassland. Shutterbugs flock to see for themselves the marvel of splendid colors around the mountains and waters, many of whom have travel a long distance and even camp here only to capture a moment of the nature wonder. The silver birch turns golden, while the larch is still proudly green. You will find yourself drowned in the intoxicating red of the wild fruits as well as the glamour of flowers in full blown. And your heart will be lingering on the woods as its time for the wild fruits to ripe. The picturesque Arxan in Autumn is indeed a fairyland only exists in a dream that satisfies all your fantasies. If itrains heavily on Saturday night, some elderly Chinese will say it is because Zhinu, or the Weaving Maid, is crying on the day she met her husband Niulang, or the Cowherd, on the Milky Way. Most Chinese remember being told this romantic tragedy when they were children on Qixi, or the Seventh Night Festival, which falls on the seventh day of the seventh lunar month, which is usually in early August. This year it falls on Saturday, August 2. Folklore Story As the story goes, once there was a cowherd, Niulang, who lived with his elder brother and sister-in-law. But she disliked and abused him, and the boy was forced to leave home with only an old cow for company. The cow, however, was a former god who had violated imperial rules and was sent to earth in bovine form. One day the cow led Niulang to a lake where fairies took a bath on earth. Among them was Zhinu, the most beautiful fairy and a skilled seamstress. The two fell in love at first sight and were soon married. They had a son and daughter and their happy life was held up as an example for hundreds of years in China. Yet in the eyes of the Jade Emperor, the Supreme Deity in Taoism, marriage between a mortal and fairy was strictly forbidden. He ordered the heaven troop to catch Zhinu back. Niulang grew desperate when he discovered Zhinu had been taken back to heaven. Driven by Niulangs misery, the cow told him to turn its hide into a pair of shoes after it died. The magic shoes whisked Niulang, who carried his two children in baskets strung from a shoulder pole, off on a chase after the empress. The pursuit enraged the empress, who took her hairpin and slashed it across the sky creating the Milky Way which separated husband from wife. But all was not lost as magpies, moved by their love and devotion, formed a bridge across the Milky Way to reunite the family. Even the Jade Emperor was touched, and allowed Niulang and Zhinu to meet once a year on the seventh night of the sevent