再论固体渗碳剂中碳酸盐的催化机理

Re-exploring on Catalyzing Mechanism of Carbonate in Pack Carburizing

本文评论了文献中广为引用的氧迁移催化机理 (OTT)是难以令人相信的 ;其次详述了“电子循环接受催化理论”(ECDAT)。这个理论认为 :催化剂的催化作用是电子迁移形式。加入的催化剂有利于被扭曲的碳分子轨道恢复到原始的对称平衡状态 ,从而加速CO气体的生成。催化剂的催化活性大小取决于加入催化剂的电负性大小。凡是比碳电负性小的元素或化合物均具有催化活性 ;电负性越小 ,催化活性越大。反之 ,凡是比碳电负性大的元素或化合物均具有毒性 ,电负性越大 ,毒性越大。元素或化合物的电负性大小与它们在反应条件下的化学态密切相关。许多试验数据与本理论相吻合。

WT6BZ][ST6BZ] This paper contains two parts.First,the oxygen transfer theory(OTT) which is quoted extensively in a number of literature has been criticized in detail and the OTT is incredible.Second,an Electron Cyclic Donor-Acceptor Catalyzing Theory(ECDAT)was proposed .Upon this theory the catalytic effect of catalyst is attributed to the electron transfer.The catalyst facilitates the restoration of the distorted carbon molecular orbits to original symmetric state and therefore to enhance the formation rates of the carbon monoxide.The relative catalytic activity depends on the electronegativity of the catalyst involved.The elements or compounds with lower electronegativity than that of carbon possess the catalytic activity.The lower the electronegativity,the higher the catalytic activity.On the contrary the elements or compounds with higher electronegativity than that of carbon possess poisoning effect.The higher the electronegativity,the more serious the poisoning effect.The electronegativity of elements or compounds depends on the chemical state under different reaction condition.A number of data are identical with this theory.