催化反应制备碳化硅纳米粉体的密度泛函理论计算及实验研究

发布时间：2018-04-13 23:40

  本文选题：密度泛函理论 + 碳化硅纳米粉体　； 参考：《高等学校化学学报》2017年09期

【摘要】：以Si_(55),Si_(43)M_(12)和Si_(37)M_(18)(M=Fe,Co或Ni)团簇为模型,采用密度泛函理论(DFT)研究了Fe,Co及Ni纳米团簇催化硅粉转化为SiC的机理.计算结果表明,Fe,Co及Ni纳米催化剂先与Si形成合金,拉长并弱化Si—Si键的强度,起到活化Si粉的作用;合金的形成有利于C原子的吸附及Si原子和C原子间的反应;Fe的催化能力强于Co和Ni.在此基础上,以Si粉和酚醛树脂为原料,以Fe,Co及Ni硝酸盐为催化剂前驱体,通过微波加热反应制备了3C-SiC纳米粉体.研究了催化剂种类、反应温度、催化剂用量和反应时间等对制备3C-SiC纳米粉体的影响.结果表明,催化剂Fe,Co和Ni的加入均可显著降低3C-SiC的合成温度.当以2.0%(质量分数)的Fe为催化剂时,Si粉在1100℃下反应30 min后即可全部转化为3C-SiC纳米粉体;而在相同条件下,无催化剂时Si粉的完全转化温度为1250℃;Fe的催化效果优于Co和Ni,与DFT计算结果吻合.
[Abstract]:The mechanism of the conversion of silica fume to SiC catalyzed by FeCo and Ni nanoclusters was studied by using density functional theory (DFT) based on the model of SiS5 / S / SiS / P / M _ (12) and SiS _ (37) / M _ (18) / M _ (18) / T _ (2) / T _ (2) / T _ (2) / T _ (2) / T _ (2) / T _ (T _ (T)) model.The calculated results show that FeCo and Ni nanocatalysts form alloys with Si at first, elongate and weaken the strength of Si-Si bond, and play the role of activating Si powder.The formation of the alloy is advantageous to the adsorption of C atom and the reaction between Si atom and C atom. The catalytic activity of Fe is stronger than that of Co and Ni.On this basis, 3C-SiC nanocrystalline powders were prepared by microwave heating reaction using Si powder and phenolic resin as raw materials and FeCo and Ni nitrate as catalyst precursors.The effects of catalyst type, reaction temperature, amount of catalyst and reaction time on the preparation of 3C-SiC nanoparticles were studied.The results show that the addition of FeCo and Ni can significantly decrease the synthesis temperature of 3C-SiC.When Fe (2.0%) was used as catalyst, Si powder could be converted to 3C-SiC nano-powder after 30 min reaction at 1100 鈩，

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