CO_2 Reforming of CH_4 over Ni/CeO_2-ZrO_2-Al_2O_3 Prepared by Hydrothermal Synthesis Method

The Ni/CeO_2-ZrO_2-Al_2O_3 catalyst with different Al_2O_3 and NiO contentswere prepared by hydrothermal synthesis method. The catalytic performance for CO_2 reforming of CH_4reaction, the interaction among components and the relation between Ni content and catalyst surfacebasicity were investigated. Results show that the interaction between NiO and Al_2O_3 is strongerthan that between NiO and CeO_2-ZrO_2. The addition of Al_2O_3 can prevent the formation of largemetallic Ni ensembles, increase the dispersion of Ni, and improve catalytic activity, but excessAl_2O_3 causes the catalyst to deactivate easily. The interaction between NiO and CeO_2 results inmore facile reduction of surface CeO_2. The existence of a small amount of metallic Ni can increasethe number of basic sites. As metallic Ni may preferentially reside on the strong basic sites,increasing Ni content can weaken the catalyst basicity.

STRUCTURE STUDIES OF PLATINOTHIONEINS BY USING EXTENDED X—RAY ASSORPTION FINE STRUCTURE SPECTROSCOPY

The metal binding sites in the two Pt containing metallothioneins (Pt-MT and Pt14MT) were examined by means of Pt(II) L3-edge extended X-ray absorption rine structure(EXAFS) spectroscopy.Comparisons between the phase and amplitude functions derived from the isolated shells to those of Pt…Pt.Pt-S and Pt-N model components showed that each platinum in Pt7MT was coordinated by four sulfur atoms at a distance of 2.31±0.01 A.Analysis of the outer shell data of platinum atom in Pt7MT indicated backscattering platinum atom at approximate 4.29A.Strkingly different structural parameters had been obtained for the Pt14MT species.fitting of the first shell revealed that each platinum was coordinated by two sulfurs at the distance of 2.3-±0.02A and two nitrogens at 2.02±0.02A.The results of the work provided the detailed information concerning the local environments of the coordinated Pt(II) in these two platinothioneins.

FTIR and EXAFS investigations of microstructures of gold solvent extraction：hydrogen bonding between modifier and Au（CN）2^—

The microstructures of loaded organic phases of three quaternary amine solvent extraction systems for gold,which were N263-xylene,N263-tributyl phosphate(TBP)-dodecane and N263-2 -ethylhexanol (isooctanol)-dodecane(N263-trialkylmethylammonium chloride;alkyl=C8-C10),were studied by Fourier transform infrared (FTIR) spectroscopy and extended X-ray abso\rption fine structure(EXAFS) spectroscopy. According to the EXAFS results,it was found that the gold coordination environment was the same before and after extraction.However,the C≡N stretching vibrations of Au(CN)2-were also found to be different,In order to explain the differences in the IR characteristics of C≡N in the three extraction systems,three microstructure models are proposed.For the N263-xylene system,the model is a simple ion pair.For the other two systems with a modifier(TBP and isooctanol),the models are two supramolecular structues based on hydrogen bonding between the modifier and Au(CN)2^-.Some related work such as on the hydration of acetonitrile and the fine structure of C≡N in solid K Au(CN)2 was also performed in order to offer additional supporting evidence for the reliability of the proposed models.