Cerium (IV) hydrogenphosphate as an intercalation matrix for Pd(II)

Cerium (IV) acid phosphate (CeP) belongs to the class of acid phosphates of tetravalent metals. In particular, this material assumes the form of fibrous self-supported sheets [1]. It presents the property of ion-exchange towards cations. In the present work it is intended to incorporate palladium in layered matrix of varying cristallinities as an effort to obtain nanocoposites for organometallic catalysis. CeP was synthesized according to previous work [2]. 6 mol L-1 H3PO4 aqueous solution was added dropwise to a 0.05 mol L-1 (NH4)2Ce(NO3)6 aqueous solution at 90oC and the mixture was kept at this temperature for 0h, 2h and 4h. The solids were characterized by XRD, FTIR and TGA. The XRD patterns (Fig. 1) show the improvement in cristallinity as the treatment time is increased. For the 4hour-time treated material, the most cristalline, we proceeded to the ion-exchange process with Pd (Fig. 2a). It was observed a dramatic decrease of peak intensity but there was no change concerning the 2value of the interlayer space peak (2~8.0o). The FTIR spectra (Fig.2b) show that PO-H stretching mode at 2380 cm-1 loses intensity after Pd impregnation signaling ion-exchange. TGA curves point to 3.8 and 2.8 H2O for CeP and CeP-Pd hydration evidencing partial dehydration after intercalation. ICP-OES, Raman and SEM characterizations are underway.