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The reusability of supported Ni0-nanoparticles was tested undersimilar reaction condition. The catalyst was separated by ﬁltration,washed, dried and reused for Hantzsch condensation for a fresh reac-tion mixture up to run no. 4. The results in Fig. 5 showed that there is a decrease in product yield in subsequent reuse i.e. 95% in run no. 1 de-creased to 81% in run no. 4. The stability of the used catalyst recovered after run no. 1 was investigated by HRTEM [Fig. 4] and there is no signif-icant change in size or shape of the Ni0-nanoparticles. The nanoparticles were well dispersed on the support and sized in the range of 3–10 nm. The effect of nickel loading of 1.0, 3.0 and 4.85 wt.% of the catalyst, on the condensation reaction of benzaldehyde, dimedone, ethylacetoace-tate, and ammonium acetate was investigated and the corresponding yields of 41.3%, 69% and 95% were found. This clearly indicates that4.85 wt.% of Ni nanoparticles showed the best efﬁcacy. A comparison of the efﬁciency of catalytic activity of the modiﬁed Montmorillonite supported Ni0-nanoparticles with several previous methods is presented in Table 3. The results show that the present method is better compared to some of the earlier reports in terms of yield and reaction time.

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筆墨輕點(diǎn): 金幣+25, 翻譯EPI+1 2014-09-25 20:17:20

被支撐的Ni0納米粒的重復(fù)利用性在相似的條件下進(jìn)行了測(cè)試。過慮分離后的催化劑，經(jīng)清洗、干燥重新用于新反應(yīng)混合物的Hantzsch縮合反應(yīng)，這樣的過程可以重復(fù)4次。圖5表明，之后（催化劑）重新利用時(shí)，生成物的產(chǎn)量會(huì)降低，例如從第一次的95%下降到第4次的81%。HRTEM研究了第一次催化后重新恢復(fù)利用的（催化劑）的穩(wěn)定性（圖4），Ni0納米粒的尺寸和形狀都沒有很大的變化，充分地分布于支撐物中，尺寸從3nm到10nm不等。研究了含1%、3%，4.85% 鎳的催化劑催化苯甲醛、雙甲酮、乙酰乙酸乙酯、乙酸銨縮合反應(yīng)時(shí)的效果，它們的生成物產(chǎn)量分別是41.3%, 69% 和 95%。這清楚說明，含4.85% 鎳的納米粒催化效率最高。表3對(duì)比了改性Montmorillonite支撐的Ni0納米粒與之前幾種方法的催化效率。結(jié)果顯示，對(duì)比于早期的研究成果，本文提出的方法在生成物產(chǎn)量和反應(yīng)時(shí)間方面更優(yōu)越。

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2樓2014-09-25 18:57:18