畢業(yè)論文-錳氧化物合成及催化酯化反應的研究.doc

錳氧化物合成及催化酯化反應的研究摘 要：本論文通過對一系列納米結(jié)構錳氧化物的制備及對其性質(zhì)的表征，旨在尋找具有特殊性能的新型催化劑及其制備方法。實驗利用Zn(Ac)2 和Mn(Ac)2為原料，H2O2為氧化劑在NaOH溶液中共沉淀制備ZnMn2O4?；谶@種方法，改變反應條件（反應物摩爾配比，氧化劑用量，陳化時間，反應溫度等）最終在常溫常壓的溫和條件下得到了單一晶形的均勻納米顆粒，粒徑在10nm 20nm。同時也利用水熱法制得了-MnO2納米線，-MnO2納米顆粒。最后利用XRD，TEM對所制得的產(chǎn)品進行表征。 利用在不同條件下制得的一系列錳的氧化物催化合成乙酸異戊酯，分別得到其酯化率為：-MnO2納米線：80%左右；-MnO2納米顆粒：86%左右；ZnMn2O4（煅燒200500）：88%94%。關鍵詞：納米結(jié)構錳氧化物；納米顆粒；水熱法；乙酸異戊酯；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 納米技術的發(fā)展為新材料開發(fā)提供了一條全新的途徑，并注入了新的活力，必將推動信息、能源、環(huán)境、生物、農(nóng)業(yè)、國防等領域的技術創(chuàng)新，成為繼工業(yè)革命以來，三次主導技術引發(fā)的產(chǎn)業(yè)革命以后的第四次浪潮的基礎。納米技術既包含了豐富的科學內(nèi)涵，又給人們提供了廣闊的創(chuàng)新空間，從而成為物理，化學，材料科學，生命科學以及信息科學發(fā)展的新領地。人們正在利用納米技術在納米尺度范圍內(nèi)認識和改造自然，通過直接操縱和安排原子，分子而創(chuàng)造新材料。納米技術的出現(xiàn)標志著人類科學技術已進入了一個新的時代納米科技時代。納米是一個長度單位（1nm=10-9m），納米科學是研究納米尺度范疇內(nèi)（1100nm）原子，分子和其它類型物質(zhì)運動的變化的科學。而納米技術則是在納米尺度范圍內(nèi)對原子，分子等進行操縱和加工的技術。納米科學技術是一門多學科交叉的，基礎研究和應用開發(fā)緊密聯(lián)系的高新科學技術。它包括納米材料學，納米電子學，納米機械加工學，納米生物學，納米化學，納米力學，納米物理學和納米測量學等若干領域1。納米材料因其體積效應和表面效應等在磁性、催化、光吸收、熱阻和熔點等方面顯示出特異的性質(zhì)，因而受到人們的極大關注。納米催化技術是非常重要的納米技術的分支。在過去十年間納米催化技術（主要是納米粒子在催化反應中的應用）得到了迅速發(fā)展。這方面的研究工作集中在液相中的均相催化技術和負載于基底上納米粒子的非均相催化技術。納米粒子具有比相應的體相材料大得多的比表面積，因此更適于用作催化劑。1996年，報道合成了不同形貌的過渡金屬納米粒子，探索了它們在不同催化反應中的潛在應用2。最近的研究表明對于溶膠中的同一電子遷移反應，不同形貌的鉑納米粒子作為催化劑時表現(xiàn)出不同的活性3。這種由形貌決定的催化作用突出了納米粒子作為催化劑的優(yōu)勢。顯然這些處于納米粒子棱角和邊緣的表面原子不穩(wěn)定，在化學反應中易于表現(xiàn)出催化作用，并且使粒子形貌發(fā)生改變4。1.1 納米材料的特異性能（1）表面效應指的是納米粒子的表面原子與總原子之比，隨著粒徑的變小而急劇后所引起的性質(zhì)上的變化，由于其具有很高化學活性，常用于做催化劑、助劑環(huán)境敏感性物質(zhì)等。（2）小尺寸效應在物質(zhì)的顆粒減小到納米尺度（ Zn2Mn4O8納米粒子 Mn3O4納米粒子a- MnO2納米棒市售MnO2。如果沒有催化劑存在（空白），酯化率很低。4.4.2 Zn2Mn4O8催化劑在不同溫度下煅燒后對其催化性能的影響為了研究Zn2Mn4O8納米粒子的催化性能，我們又利用在不同溫度下煅燒所得到的Zn2Mn4O8（500以上得到純態(tài)的ZnMn2O4）進行催化酯化反應，得到如下（圖4-3）酯化率和煅燒溫度之間的關系。樣品在200有最高的催化酯化率。沒有煅燒的樣品比煅燒200的樣品催化性能要差很多，我認為應該是在沒有煅燒的樣品中含有水分，而正是由于水分子的存在減小了催化劑和醇及酸的接觸面因而導致催化效率下降；而在300之后的酯化率只所以降低的原因我認為可能是由于溫度過高時，樣品顆粒長大、聚集而使得其比表面積減小所致。圖4.3 酯化率與煅燒溫度間的關系5 結(jié)論與展望本文全面系統(tǒng)地介紹了納米催化材料的特點，及其在主要的制備方法、有機合成領域的應用研究現(xiàn)狀。特別是納米結(jié)構錳氧化物在上述領域一直是研究的熱點，目前仍然存在制備方法復雜、應用研究范圍狹小等問題。在此基礎上，本文只要研究制備鋅錳復合氧化物納米材料的新方法，并進一步研究了一系列納米結(jié)構錳氧化物對合成乙酸異戊酯的催化性能，為其實際應用奠定了實驗基礎。（1）常溫常壓和水熱法成功控制合成了納米結(jié)構鋅錳復合氧化物。利用醋酸鋅（Zn(Ac)2 2H2O）和醋酸錳（Mn(Ac)24H2O）為原料，雙氧水為氧化劑，改變各方面反應條件（反應物摩爾配比，氧化劑用量，陳化時間，反應溫度等），最終在常溫常壓的溫和條件下得到了單一晶形的均勻ZnMn2O4復合氧化物納米顆粒17，其具有很好的催化酯化反應性能。本實驗方法簡單，條件溫和，無須用到高溫高壓的裝置，操作安全可靠，后處理只須在200的烘箱中烘烤幾個小時就可以了。同時也利用水熱法制得了-MnO2納米線，對比了各種不同錳的氧化物的物理化學性質(zhì)。（2）利用所制得的各種納米結(jié)構錳氧化物對合成乙酸異戊酯酯化反應的催化活性進行實驗。以所制備的納米結(jié)構錳氧化物為催化劑，采用反應蒸餾技術進行了乙酸異戊酯的合成研究。實驗發(fā)現(xiàn)，ZnMn2O4復合氧化物納米顆粒對合成乙酸異戊酯酯化反應具有優(yōu)良的催化活性。在相同反應條件下，它催化異戊醇的酯化率明顯高于以a-MnO2納米棒、- MnO2納米顆粒和Mn3O4納米粒子作為催化劑時的酯化率（催化乙酸異戊酯合成反應的最佳工藝條件為：酸醇摩爾比為1.5:1，催化劑量為反應物質(zhì)量的0.2%，反應時間為210 min）。在此條件下以ZnMn2O4復合氧化物納米顆粒作為酯化反應的催化劑時的反應酯化率高達96%，雖然發(fā)現(xiàn)在反應過程中有部分催化劑溶解或是反應而消失，但是通過計算，即使是所有的催化劑都形成了醋酸鹽，其最佳酯化率仍然在95%以上，而且也很容易將其和所形成的酯分離開來。由于時間關系，沒有對反應后的產(chǎn)物做進一步分析，雖然結(jié)果可能存在一定的誤差，但是我覺得，這種催化劑還是很有研究價值的。謝辭本次論文是在楊則恒老師和張衛(wèi)新老師的大力支持和細心指導下順利完成的，在為期三個月的畢業(yè)設計中，因為楊則恒老師、張衛(wèi)新老師對我的悉心教導，使我不僅在實驗和理論知識方面有一定收獲，也使我明白了在科學研究中不僅要有科學的方法，嚴密的思維，更要有端正的、實事求是的科研態(tài)度，在此向兩位老師表示衷心的感謝!在實驗過程中，唐述培老師和劉岸平老師在實驗儀器及產(chǎn)物的測試方面給予了大力的支持，在此向兩位老師表示感謝。另外，本次論文得到了本實驗室的師兄，師姐及各位同學的無私幫助，借此機會一并向他們表示感謝！參考文獻1 許并社.納米材料及應用技術M.化學工業(yè)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 張全勤,張繼文.納米技術新進展M.國防工業(yè)出版社,2005.99.6 閻子峰.納米催化技術M.化學工業(yè)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 王占國. 納米半導體材料的制備技術J. 微納電子技術, 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 趙立志. 納米材料的應用J. 天津化工, 2003, 17(5): 39- 41.13 何順愛，周雙喜等.水熱沉淀法制備ZnO納米粉體J.桂林工學院學報，2004，24（1）: 80-84.14 常照榮，劉院英等.濕法制備納米二氧化錳及其電化學性能的研究J.河南師范大學學報(自然科學版)，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.納米復合氧化物催化劑研究進展J.無機鹽工業(yè)，2004,36（4）: 1-2.請您刪除一下內(nèi)容，O(_)O謝謝！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