The Influence of the Catalyst Preparation on the Catalytic Properties of Ni/X-Zeolites

鎳沸石觸媒之製備方法對其性質與結構之影響

簡淑華(Shu-Hua Chien) ； 呂光烈(Kuang-Lieh Lu) ； 黃小文(Hsiau-Wen Huang) ； 黃俊敏(Jiunn-Min Hwang)

《中央研究院化學研究所集刊》 33期 (1986/03) Pp. 81-91

https://doi.org/10.6522/BICAS.1986.33.11

摘要

我們以初濕含浸法及離子交換法製備鎳沸石觸媒，研究不同之製備方法對一氧化碳加氫反應所顯示的觸媒活性之差異。觸媒之特性分析包括表面積及化學吸附之測定，程溫還原，程溫脫附，X－光繞射測定及一氧化碳吸附之紅外線光譜測定。我們發現觸媒活性與其特性間呈現很好的關連性，並藉此得以對複雜的觸媒性質有所了解。大抵上，不論如何製備，還原後的鎳沸石觸媒顯示鎳粒子移至沸石表面，由離子交換法製備者其進入沸石中之鎳離子極具游移性，在還原過程中，不止難於還原，且移至表面時易於結塊，使鎳之分散度不良，活化中心數大大減少，一氧化碳難於接近，是故導致其低觸媒活性，而無法比美於含浸法所製備者。後者之特定活性（TOF）約為前者之四倍。

並列摘要

The influence of the catalyst preparation on the catalytic activity of Ni/X-zeolite for CO/H_2 reactions have been investigated. The impregnated sample shows a higher number of turnover frequency by a factor of four in comparison with the ion-exchanged sample under the same reduction and reaction conditions. The prepared catalysts were characterized by surface area and volumetric chemisorptions measurements, temperature programmed reduction and desorption profiles, X-ray diffraction, and infrared spectra of the chemisorbed carbon monoxide. A satisfactory correlation between the turnover frequency and the characteristics of the catalyst has allowed us to shine some lights on the intricate catalytic properties. The macroscopic topology of the reduced catalyst is hardly affected by the method of the catalyst preparation, the nickel particles were spread over the surface of zeolites after the high temperature reduction no matter what preparation method was followed. However, the mobility of nickel ions inside the zeolite cages in the ion-exchanged sample caused the difficulty in reduction, formed the large Ni crystallites on the external surface of zeolites, exhibited the poor dispersion and less active sites for the access of CO to the catalysts. The ion-exchanged sample thus disclosed a low catalytic activity.