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可樂易拉罐金蟲 (正式寫手)
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[求助]
中文摘要翻譯
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幫忙翻譯以下一段文字，謝謝啦 摘要 碳酸二甲酯（DMC）作為一種重要的有機(jī)合成中間體，廣泛應(yīng)用于高性能樹脂、溶劑等領(lǐng)域。與光氣法、氧化羰基化法相比，酯交換法由于具有反應(yīng)條件溫和、低毒、高選擇性等優(yōu)點(diǎn)，已成為DMC合成工藝研究的熱點(diǎn)。但目前該反應(yīng)體系所用催化劑在分離與重復(fù)使用等方面存在諸多不足，因此，尋找合適的催化劑及載體，提高催化劑的活性和選擇性是突破DMC合成工藝研究瓶頸的關(guān)鍵所在。 本論文采用活性較高的甲醇與碳酸乙烯酯（EC）酯交換反應(yīng)合成DMC。以堿土金屬M(fèi)g的鹽類Mg(NO3)2·6H2O為前軀體，通過等體積浸漬法負(fù)載活性組分MgO，分別制備了不同負(fù)載量的MgO/γ-Al2O3和MgO/NaY催化劑，恒溫下于油浴加熱的圓底燒瓶中催化EC與甲醇酯交換反應(yīng)合成DMC。采用X射線衍射、CO2程序升溫脫附和掃描電子顯微鏡等手段對(duì)催化劑進(jìn)行了表征。 考察了不同催化劑的催化性能，發(fā)現(xiàn)MgO/γ-Al2O3在EC與甲醇酯交換合成DMC反應(yīng)中表現(xiàn)出較高的DMC選擇性，高負(fù)載量的MgO在γ-Al2O3的表面發(fā)生團(tuán)聚造成分散度下降，因此活性下降。與γ-Al2O3載體相比，采用NaY作催化劑載體在DMC選擇性上有明顯區(qū)別，其活性遠(yuǎn)高于γ-Al2O3，微細(xì)NaY分子篩具有明確的孔道分布、較高的內(nèi)比表面積和良好的熱穩(wěn)定性，且MgO/NaY催化劑重復(fù)使用效果較好，是酯交換反應(yīng)過程適宜的催化劑�？疾齑呋に嚄l件，結(jié)果發(fā)現(xiàn)以 12%MgO/NaY為催化劑，反應(yīng)溫度為140 ℃，反應(yīng)時(shí)間3h，n(EC):n(甲醇)為1:8，催化劑用量為5%時(shí)催化性能最佳，EC的轉(zhuǎn)化率和DMC選擇性均為94.3 %，且DMC的收率達(dá)到89%。 關(guān)鍵詞：γ-Al2O3; NaY分子篩; 氧化鎂; 甲醇; 碳酸乙烯酯; 碳酸二甲酯 |
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let_us_begin
金蟲 (正式寫手)
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- 專業(yè): 化學(xué)反應(yīng)工程
【答案】應(yīng)助回帖
★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★
可樂易拉罐: 金幣+20, 翻譯EPI+1, ★★★很有幫助 2012-03-30 18:21:06
可樂易拉罐: 金幣+30 2012-04-12 21:44:12
可樂易拉罐: 金幣+20, 翻譯EPI+1, ★★★很有幫助 2012-03-30 18:21:06
可樂易拉罐: 金幣+30 2012-04-12 21:44:12
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Dimethyl carbonate (DMC) is widely used in high performance resin, solvents, etc as a kind of important synthetic organic intermediates. Compared with phosgene method and oxidation hydroformylation method, the ester exchange method has the advantages of mild reaction conditions, low toxicity and high selectivity . It has become a hot spot for DMC synthesis process research. But there are also some shortcomings for the reaction system about the separation and repetition of the catalyst ,therefore, searching for the right catalyst and carrier and improving the activity and selectivity of the catalyst are the key to break through the bottleneck for DMC synthesis process research. This paper uses ester exchange reaction to synthesize DMC by active methanol and carbonated vinyl acetate (EC) . Alkaline metal Mg of salt in Mg (NO3) 2 · 6 H2O is used as the precursor, MgO active components is loaded through the volumetric immersion method , , the different load of MgO/gamma-irradiation Al2O3 and MgO/NaY catalyst are prepared respectively . the catalysts prepared are used in ester exchange reaction under constant temperature of heating oil bath in the circle of the flask . the X-ray diffraction, CO2 temperature programming desorption and warming scanning electron microscopy means are used for characterization of the catalyst. After examining the different catalytic performance of the catalysts ,we find MgO/gamma-irradiation Al2O3 showed a higher DMC seletivity in the ester exchange reaction . high load of MgO gamma-irradiation Al2O3 in the surface of is reuinted and resulted in the decline of dispersion , so activity decreases . compared with gamma-irradiation Al2O3 carrier , the catalyst using NaY as the carrier showed higher selectivity and activity . NaY zeolite has clear distribution of holes and high specific area ,as well as the excellent thermal stability .besides , MgO/NaY catalyst can be in repeated use , so it is a good catalyst for ester exchange reaction . Investigation of catalytic process condition showed that under the condition of 12% MgO/NaY as catalyst, reaction temperature 140 ℃, reaction time 3 h, n (EC) : n (methanol) for the 1:8, catalyst for 5%, it has the best catalytic performance , the EC conversion and selectivity DMC are 94.3%, and the DMC yield reached 89%. |
3樓2012-03-30 16:54:43
可樂易拉罐
金蟲 (正式寫手)
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- 注冊(cè): 2009-10-06
- 性別: MM
- 專業(yè): 色譜分析
2樓2012-03-28 09:52:29
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