Ni/AC催化剂的分散阈值及阈值效应  

Dispersion Threshold and Threshold Effect of Ni/AC Catalyst

作　　者：刘金红[1,2] 张倩[1] 姚虎卿[1] 

机构地区：[1]南京工业大学化学化工学院 [2]南通职业大学化学工程系,江苏南通226007

出　　处：《催化学报》2006年第12期1139-1143,共5页

基　　金：江苏省高校自然科学研究计划(04KJD530147)资助项目.

摘　　要：采用浸渍法制备了以活性炭为载体的镍催化剂,用X射线衍射(XRD)和热重(TG)手段分别考察了前驱体及浸渍液溶剂对活性组分Ni在载体上分散度的影响.XRD测试结果表明,以水为浸渍液溶剂制得的催化剂,经550℃焙烧后,前驱体为Ni(NO3)2时,Ni的分散阈值为0.065g/g,而前驱体为NiAc2时,Ni的分散阈值为0.058g/g.对于前驱体为Ni(NO3)2的催化剂,若浸渍液溶剂用甲醇,Ni的分散阈值则为0.082g/g,比水作溶剂时的阈值大.说明前驱体镍盐中的阴离子和浸渍液溶剂均对活性物种与载体之间的相互作用有影响,从而导致镍的分散容量有差异.TG的阈值分析结果略小于XRD的测试值.活性评价结果显示,负载Ni催化剂在甲醇气相羰基合成醋酸反应中存在较为明显的阈值效应.The nickel catalysts supported on activated carbon were prepared by the impregnation method. The effects of nickel precursors, such as Ni(NO_3)_2, NiAc_2, and NiCl_2, and solvents of dipping solution, such as water and ethanol, on the Ni dispersion degree were studied by X-ray diffraction(XRD) and thermogravimetry (TG). The XRD results showed that when the calcination temperature was 550 ℃ and water was used as the solvent, the nickel threshold was 0.065 g/g using Ni(NO_3)_2 as precursor and 0.058 g/g using NiAc_2 as precursor. The threshold of the catalyst with the Ni(NO_3)_2 precursor was 0.082 g/g in methanol and larger than that in water. Anions of nickel salts and solvents of dipping solution influenced the interaction between the active substance and support, which resulted in different dispersion capacity. The threshold obtained by TG was smaller than that by XRD. The results of catalyst performance experiments indicated the threshold effect of supported Ni catalysts existed in the carbonylation of methanol to produce acetic acid.

关 键 词：镍 前驱体 活性炭 负载型催化剂 阈值 甲醇 羰基合成 醋酸 

分 类 号：O643.36[理学—物理化学]