Characterization of Au-Rh/TiO2 bimetallic nanocatalysts by CO and CH3CN adsorption: XPS, TEM and FTIR measurements.

نویسندگان

  • János Kiss
  • Róbert Németh
  • Akos Koós
  • János Raskó
چکیده

On X-ray photoelectron spectra of the Au-Rh/TiO2 catalysts the position of Au4f peak was practically unaffected by the presence of rhodium, the peak position of Rh3d, however, shifted to lower binding energy with the increase of gold content of the catalysts. Rh enrichment in the outer layers of the bimetallic crystallites was experienced. The bands due to Au0-CO, Rh0-CO and (Rh0)2-CO were observed on the IR spectra of bimetallic samples, no signs for Rh+-(CO)2 were detected on these catalysts. The band due to CH3CN on Lewis acid centers shifted to lower wavenumbers with the increase of Rh content, which shows that the strength of Lewis acid sites weakens with the increase of Rh content of the catalysts. CH3CN, on the other hand, dissociates producing CN(a) species even at this temperature. From the shift to higher wavenumbers of the band due to CN(a) the strengthening of the C-N bond with increasing Rh content has been established. The results were interpreted by electron donation from titania through gold to rhodium and by the higher particle size of bimetallic crystallites. The effects of catalyst composition, reaction temperature and composition of the reacting gas mixtures have been studied on the oxidation of CO in the presence of hydrogen (PROX process). The presence of both O2 and H2 reduced the surface concentration of CO adsorbed on metallic sites. Mass spectroscopic analysis of the gas phase showed that gaseous CO2 formed in the highest amount in CO+O2 mixture, the presence of H2 suppressed the amount of CO2 produced. This negative effect of hydrogen was the lowest on 1% Rh/TiO2, the highest inhibition was observed on Au/TiO2 systems.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

CHARACTERIZATION OF Au-Rh AND Au-Mo BIMETALLIC NANOCLUSTERS ON TiO2(110): A COMPARATIVE STUDY

Gold-rhodium and gold-molybdenum layers were prepared on a nearly stoichiometric titania and characterized by LEIS, XPS and STM. In the Au-Rh bimetallic system, Rh atoms impinged onto Au clusters pregrown on TiO2(110) became covered by gold atoms. In contrast, Mo caused the disruption of gold nanoparticles.

متن کامل

Enhancement of the Stability of Au-Cu/AC Acetylene Hydrochlorination Bimetallic Catalyst with Melamine Treated Support

This paper highlights the experimental and theoretical studies on the Melamine treated Active Carbon (MAC) support for an Au-Cu bimetallic catalyst in acetylene hydrochlorination reaction. Compared to the original Active Carbon (AC) loaded with the same amount of 0.1wt% Au and 1.0wt% Cu,  MAC supported catalyst(MACH), wherein Carbon/C6...

متن کامل

Understanding and controlling the structure and segregation behaviour of AuRh nanocatalysts

Heterogeneous catalysis, which is widely used in the chemical industry, makes a great use of supported late-transition-metal nanoparticles, and bimetallic catalysts often show superior catalytic performances as compared to their single metal counterparts. In order to optimize catalyst efficiency and discover new active combinations, an atomic-level understanding and control of the catalyst stru...

متن کامل

Green Approach to Synthesis of Pt and Bimetallic Au@Pt Nanoparticles Using Carica Papaya Leaf Extract and Their Characterization

This study reports a green approach to synthesis of monometallic platinum nanoparticles (Pt NPs) and bimetallic aurium@platinum nanoparticles (Au@Pt) using aqueous leaf extract of Carica papaya as a reducing and stabilizing agent. The nature and morphology of as-synthesized PtNPs and bimetallic Au@Pt NPs were characterized using UV/vis spectroscopy (UV–vis), high resolution transmission electro...

متن کامل

Synthesis and Characterization of Carbon Nanotubes Catalyzed by TiO2 Supported Ni, Co and Ni-Co Nanoparticles via CCVD

Monometallic and bimetallic Ni and Co catalytic nanoparticles supported on Titanium dioxide (rutile phase) substrate were prepared by wet impregnation method. These nanoparicles were used as catalysts for synthesis of multiwalled carbon nanotubes (MWCNTs) from acetylene decomposition at 700°C by the catalytic chemical vapor deposition (CCVD) technique. The nanomaterials (catalyst and CNTs) were...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Journal of nanoscience and nanotechnology

دوره 9 6  شماره 

صفحات  -

تاریخ انتشار 2009