Environmentally friendly reduction of a platinum catalyst precursor supported on polypyrrole

Abstract

Supported metals are traditionally prepared by impregnating a support material with the metal precursor solution, followed by reduction in hydrogen at elevated temperatures. In this study, a polymeric support has been considered. Polypyrrole (PPy) has been chemically synthesized using FeCl 3 as a doping agent, and it has been impregnated with a H 2 PtCl 6 solution to prepare a catalyst precursor. The restricted thermal stability of polypyrrole does not allow using the traditional reduction in hydrogen at elevated temperature, and chemical reduction under mild conditions using sodium borohydride implies environmental concerns. Therefore, cold RF plasma has been considered an environmentally friendly alternative.Ar plasma leads to a more effective reduction of platinum ions in the chloroplatinic complex anchored onto the polypyrrole chain after impregnation than reduction with sodium borohydride, as has been evidenced by XPS. The increase of RF power enhanced the effectiveness of the Ar plasma treatment.A homogeneous distribution of platinum nanoparticles has been observed by TEM after the reduction treatment with plasma. The Pt/polypyrrol catalyst reduced by Ar plasma at 200 watts effectively catalyzed the aqueous reduction of nitrates with H 2 to yield N 2 , with a very low selectivity to undesired nitrites and ammonium by-products. † Electronic supplementary information (ESI) available. See

Green synthesis of polypyrrole-supported metal catalysts: application to nitrate removal in water

“…IR spectrum of polypyrrole aer impregnation with H 2 PtCl 6 $6H 2 O (Fig. 23 On the other hand, the N 1s spectra (Fig. This suggests that platinum may interact with the polypyrrole chain through the nitrogen atom, which is consistent with previous results.…”

“…1) show that synthesized polypyrrole and also the prepared catalysts are mainly amorphous. 23 Therefore, this platinum chlorocomplex induces a more ordered arrangement of the polypyrrole chains. 25 Additionally, polypyrrole impregnated with Pt and Sn precursors shows a sharp peak at q ¼ 33.00 , which is more evident when the Pt : Sn ratio is 1 : 1, and corresponds to the scattering of platinum ions anchored to N in polypyrrole.…”

“…2a) shows the typical bands of this material 29 ( Table 1). 23 XPS analysis of chemically synthesized polypyrrole (ESI Table 1 †) shows C and N from the polymeric chain, as well as Cl from the FeCl 3 oxidant used for the chemical polymerization of polypyrrole. Some degree of surface oxidation is detected (band at 1694 cm À1 of C]O stretching) which may be due to polypyrrole backbone oxidation through free radical oxygen insertion, and may also be produced by exposure of the polymer to air.…”

Amphiphilic polymer-Ag composite microgels with tunable catalytic activity and selectivity

“…Among the available support materials, polymer-type carriers or matrices with various functional groups as anchor sites for loading MNPs have attracted attention for practical application because these materials are highly tunable and can further improve the properties of MNPs [8][9][10][11][12]. The main advantage of polymer supports is that the polymer chain contributes to changes in the microenvironments surrounding MNPs because of the thermodynamic compatibility of the polymer matrix and reaction medium.…”

UV-Catalytic Preparation of Polypyrrole Nanoparticles Induced by H2O2

“…43 The peaks at 400.2 and 401.2 eV are attributed to neutral and positively charged nitrogen atoms of PPy, respectively. 44,45 Page 9 of 56…”