Catalysis and characterization of a rugged lead ruthenate pyrochlore membrane catalyst

Catalytic polymeric membranes: Preparation and application

“…Ke et al [57] prepared a rugged lead ruthenate pyrochlore (Py) catalyst incorporated Nafion 417 membrane (jNPyj). Surface morphological analysis shows the active Py catalyst mainly exposed in the outer surface and hence quite suitable for catalytic applications.…”

A rugged lead-ruthenate pyrochlore membrane catalyst for highly selective oxidation of alcohols

“…The |NPy| catalyst was prepared by in-situ precipitation directly inside the Nafion 417 membrane (after ion-exchanged with Ru 3+ and Pb 2+ ions) in alkaline medium under constant O 2 purging as per our previous reported procedure and the net Py loading was measured as 6 wt.% (76 mol/g Py units) by TGA [32]. Fig.…”

“…Prior to the electrochemical measurements, the NPyCME was pretreated for five continuous cycles in base electrolyte solution at a scan rate of 50 mV/s. Formation of the fine Py crystalline units was confirmed by Xray diffraction technique for both |NPy| and NPyCME systems [27,28,32].…”

“…As can be seen in Table 1, the addition of H 2 O 2 cooxidant can yield 84% of conversion and >99% of selectivity to benzaldehyde in 24 h at T = 80 • C with a turnover number (TON) and TOF of 381 and 16 h −1 , respectively (Table 1, entry 2) [32]. Interestingly, the benzyl alcohol oxidation reaction can be completed within 3 h with >99% conversion and selectivity when the co-oxidant was changed from H 2 O 2 into NaOCl at a lower reaction temperature of T = 40 • C (entry 4).…”

“…Later it was prepared as a rugged lead-ruthenate pyrochlore (Py, Pb 2 Ru 2 O 7 ) Nafion membrane catalyst (designated as |NPy|) and used for selective sulfoxidation application coupled with a Ru(bpy) 3 2+ photosensitizer [31]. Recently the |NPy| catalyst was characterized by physicochemical techniques of X-ray diffraction (XRD), thermogravimetry (TGA), scanning electron microscopy (SEM), and atomic force microscopy (AFM) with a main conclusion that the Nafion membrane can assist for the nucleation of nanosized Py crystalline units inside the ionic cluster with a net Py loading of ∼6 wt.% [32]. The catalytic activity of the |NPy| was further evaluated using a model reaction of benzyl alcohol oxidation coupled with an H 2 O 2 co-oxidant at 80 • C. The heterogeneous pseudo first order constant (k h ) and turnover frequency (TOF) were measured as 2.03 × 10 −5 s −1 and 16 h −1 , respectively.…”