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通过4个典型反应:(1)氯苯氢解、(2)肉桂醛选择还原、(3)二甲亚砜金属取代反应、(4)烯烃催化加氢,比较了用纳米NaH与商品NaH时各反应初始反应速率的差别,进而研究纳米NaH的高化学反应活性。实验表明,在(1)、(2)、(3)3个化学计量反应中,用纳米NaH做还原剂比用商品NaH时化学反应初始速率分别提高230、120、110倍;在烯烃催化加氢反应中,纳米NaH与Cp,TiCl2组成的催化剂有极高的催化活性,而商品:NaH与Cp2TiCl2组成的催化剂无催化活性。当NaH颗粒尺寸减小到纳米数量级时,表面分子所占的比率剧增,大量的表面分子和表面缺陷导致表面能增大,这可能是它作为催化剂一个组分时具有高催化活性的关键因素。大的比表面积和高的表面能是决定纳米NaH高反应活性的2个主要因素,至于哪个因素占主导地位,则取决于不同的反应类型。
Through four typical reactions: (1) chlorobenzene hydrogenolysis, (2) cinnamaldehyde selective reduction, (3) dimethylsulfoxide metal substitution reaction, (4) olefins catalytic hydrogenation, compared with nano NaH and commercial NaH The initial reaction rate of each reaction difference, and then study the high chemical activity of nano-NaH. The experimental results show that in the three stoichiometric reactions of (1), (2) and (3), the initial rates of chemical reaction increase by 230, 120 and 110 times respectively when nano NaH is used as reductant compared with commercial NaH; Hydrogen reaction, nano-NaH and Cp, TiCl2 composed of catalyst has a very high catalytic activity, and commodity: NaH and Cp2TiCl2 catalyst composed of no catalytic activity. When the size of NaH particles decreases to the order of nanometers, the proportion of surface molecules increases sharply, and the surface energy increases due to a large number of surface molecules and surface defects, which may be the key factor of high catalytic activity when it is a component of catalyst . Large specific surface area and high surface energy are the two main factors that determine the high reactivity of nano-NaH. As for which factor is dominant, it depends on different reaction types.