NaY超笼内[Pt_3(CO)_3(μ_2-CO)_2]_n^(2-)(n=3,4)簇合物的合成、表征及其催化CO+NO的反应性能

SYNTHESES OF [Pt_3(CO)_3(μ_2-CO)_3]_n^(2-)(n=3,4) CLUSTERS INSIDE NaY ZEOLITES, THEIR CHARACTERIZATION AND ACTIVITY IN CO + NO REACTION

在NaY分子筛超笼内合成了桔黄色的[Pt_9(CO)_(18)]^(2-)和深绿色的[Pt_(12)(CO)_(24)]^(2-)簇合物。前者给出2056和1798cm^(-1)的线式和桥式羰基特征红外谱带;后者给出2080和1824cm^(-1)谱带。与在THF溶液中结果相比,NaY内合成的羰基簇合物的线式v_(CO)向高波数位移,而桥式v_(CO)向低波数位移。EXAFS为Pt羰基簇合物在分子筛内的规整形成提供了证据。NaY内Pt_9和Pt_(12)羰基簇合物在NO+CO反应中显示了较高的催化活性及稳定性。

[Pt9(CO)18]2-/NaY (orange-brown, 2056 and 1798cm-1) and CPt12-(CO)24]2-/NaY (dark-green, 2080 and 1824 cm-1 were stoichiometrically synthesized by the reductive carbonylation of [Pt ( NH3)4]2+/NaY and Pt2+/NaY respectively.The IR bands of their linear carbonyls shift to higher frequency side, whereas the bridging CO to lower frequency side, as compared with those on the external zeolites and in solution.Pt-L3-edge EXAFS measurement of these samples demonstrate the stoichiome-tric formation of the trigonal prismatic Pt9 and Pt12 carbonyl clusters in NaY supercages.The intrazeolite Pt9 and Pt12 carbonyl clusters exhibit remarkable catalytic activity and high stability in NO reduction by CO to N2 and N2O at 473K