화학공학소재연구정보센터
Journal of Physical Chemistry B, Vol.101, No.9, 1569-1578, 1997
Influence of Preparation Variables on the Structural, Textural, and Catalytic Properties of Al-Pillared Smectites
Al-pillared montmorillonites and saponites have been prepared with different pillaring solutions and their properties compared with those of similar materials obtained following a standard procedure. Characterization of the pillared clays includes X-ray diffractometry, determination of the residual cation exchange capacity, acidity measurements (ammonia), and textural properties from nitrogen adsorption-desorption isotherms. The catalytic properties of Pt-impregnated samples have been evaluated in the hydroconversion of heptane. It is shown that the textural, structural, and surface properties of the pillared clays may be influenced to some extent by the preparation method and also by the crystallinity (stacking order) of the starting clay. The catalytic performances, however, are principally dependent on the type of clay : pillared clays issued from smectites with structural tetrahedral lattice substitutions (saponites) are significantly more active than equivalent materials produced from clays with structural octahedral substitutions (montmorillonites). The preparation method and, in particular, the nature of the pillaring solution only have a secondary effect. The catalytic results are discussed in terms of nature, content, and strength of the acid sites.