硫酸根中毒镍催化剂机理的研究

The Mechanism Study of Ni-Catalyst Poisoned by SO_4^(2-)

用硫酸镍制备植物油加氢催化剂,虽可以降低成本,但催化剂容易中毒。为了分析催化剂中毒的原因,XRD 实验表明,用硫酸镍制备催化剂时,催化剂中残存SO_4^(2-),高温还原时产生H_2S.H_2S 与活性镍反应生成Ni_3S_2.EXAFS 实验表明,在Ni_3S_2中。Ni 的3CN 空穴被S 原子嵌入,而Ni 的3CN 空穴是吸附H_2的活性位置,被S 原子占据后,使催化剂活性降低。因此用硫酸镍制备催化剂的关键步骤是在高温还原前除去催化剂中残存的SO_4^(2-)。

The catalyst of hydrogenation of edible oil can be prepared by using a cheap material-NiSO_4·7H_2O,but the catalyst has low activity.In order to analysethe reason for the low activity of catalyst,we used XRD and EXAFS methods tostudy the structure of catalyst poisoned by SO_4^(2-).It was proved by XRD and EXAFSthat there was Ni_3S_2 in the catalyst after catalyst was reduced by H_2 at hightemperature.The mechanism of SO_4^(2-) poisened Ni catalyst was determined as follows:First SO_4^(2-) react with H_2 at high temperature and form H_2S.Second,H_2S react with Niand form Ni_3S_2.In Ni_3S_2,Sulphur atom occupied 3CN vacancies on Ni cluster surfacewhich usually are thought to be the adsorption center for hydrogen.The importantstep of preparing Ni catalyst with NiSO_4·7H_2O is to remove SO_4^(2-) from catalyst beforereduction.