Ni／活性炭催化剂上还原途径及其催化性能

Reductive Paths and the Catalytic Performance over Ni/AC Catalyst

采用浸渍法制得Ni/活性炭催化剂,在惰性气氛中将其进行了不同温度的热处理,利用X射线衍射(XRD)及热重分析(TG-DTG)等手段进行了表征,在250℃,1 MPa下考察了不同还原途径对甲醇羰基化合成醋酸的影响。XRD谱图与TG-DTG曲线表明,随着热处理温度的升高,Ni(NO_3)_2于200～300℃分解,NiO则于450℃开始被还原。活性炭促进了NiO还原为金属Ni,而且热处理温度越高还原越充分。催化活性评价结果说明,惰性气氛下利用活性炭促进作用还原后的催化活性不如经还原气氛H_2处理后的高。同时两种还原方法均表明,热处理或还原温度过高,会导致催化活性下降。

The nickel catalyst supported on activated carbon was prepared by the impregnation method. The effects of thermal treatment in inert atmosphere on the properties of Ni/AC catalyst were investigated. The treated catalysts were characterized by means of XRD and TG. The activity of catalysts were tested by vapor phase carbonylation of methanol under 250 ℃ and 1 MPa. The results by XRD and TG-DTG showed that Ni （NO3）2 was decomposed at 200-300 ℃ and NiO was reduced at 450 ℃ with increasing the thermal treating temperature. NiO could be reduced to Ni by active carbon, the reduction was more efficient with increasing of the thermal treating temperature. The activity of catalysts reduced in hydrogen was higher than that in inert atmosphere with promotion of active carbon. If treating temperature was too high, the catalytic activity would decline.