Saponite catalysts with systematically varied Mg/Ni ratio: synthesis, characterization, and catalysis

A series of saponite catalysts having systematically varied Mg and Ni ratio s in the clay framework (i.e. [Mg6-0Ni0-6]-saponites) were synthesized usin g the hydrothermal synthesis method. The synthesized saponite catalysts hav e similar XRD patterns, indicating that all of the Mg and/or Ni elements ha ve been incorporated as Mg and Ni ions in the octahedral positions of the c lay framework, respectively. The results of the isopropanol dehydration rea ction show that the saponite containing only Ni (i.e. [Mg0Ni6]-saponite) wa s very active, while the other Mg-containing saponites (i.e. [Mg1-6Ni5-0]-s aponite) were inactive. The results of the pyridine-adsorption FTIR further show that the [Mg1-6Ni5-0]-saponite has Bronsted and Lewis acidic sites, w hile the [Mg1-6Ni5-0]-saponites have only Lewis acidic sites. The possible interaction between Mg and Ni ions in the octahedral positions of saponite catalysts and its influence on the catalytic activity of the catalysts is d iscussed in this paper. (C) 1999 Elsevier Science B.V. All rights reserved.