A novel method to correlate layer charge and the catalytic activity of 2 :1 dioctahedral smectite clays in terms of binding the interlayer cation surrounded by monohydrate

Ab initio total energy pseudopotential calculations were performed on 2:1 d ioctahedral smectite to rationalize an understanding of the structure and e nergetics for the same and to correlate catalytic activity of clay material s with layer charge. We have chosen two clay members from the 2:1 dioctahed ral smectite family-(1) beidellite and (2) montomorillonite-to monitor the effect of negative charge on the location of interlayer cation. Local softn ess calculation using Fukui functions generated for clusters derived from t he structures of the clay matrixes in the domain of the hard-soft acid-base (HSAB) principle were performed first to locate the active site in clay. A b initio calculations were followed to determine the most feasible orientat ion of the single interlayer water molecule in hydrated montmorillonite and beidellite. The role of hydroxyl hydrogen attached with the bridging oxyge n connected to octahedral aluminum was also monitored. It is observed that interlayer cation (Na+) has a lesser influence on hydrogen bond formation i n the presence of single water molecule. The Na+ locates closer to the subs tituted octahedral site of 2:1 dioctahedral smectite. Now, to monitor the e ffect of negative charge on the location of interlayer cation, the two stru ctures chosen were compared. A novel method to correlate catalytic activity of clay with layer charge has been formulated.