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NanoMat 2018: Bimetallic acetate complexes derived La(III)-doped TiO2 nanofibers for Claus catalysts - Ruohong Sui - University of Calgary, Canada

Ruohong Sui

Modified Titania is of great interest for industrial catalysts and photocatalysts with applications in environmental engineering. In this research, La(III) was incorporated into titanium oxoacetate complexes via a one pot sol-gel process of metal alkoxides reacting with acetic acid, evidenced by electrospray ionization mass spectrometry analysis. The resulting well-defined nanofibers were calcined to obtain 1-dimensional La-doped TiO2 materials. For comparison, lanthanum was also deposited on the surface of TiO2 nanofibers by an impregnation method. X-ray photoelectron spectroscopy analysis shows that the oxygen defect in the La-doped sample was more significant than that in the La-deposited TiO2. In addition, more interaction of lanthanum with the TiO2 matrix was observed in the nanofibers synthesized via the sol-gel method. These features of doped TiO2 nanofibers are anticipated to play a role in higher catalytic activity. In addition, both the Ladoped and deposited TiO2 nanofibrous materials exhibited excellent thermal stability. The N2-physisorption and powder x-ray diffraction characterizations show that both anatase crystallites and surface areas in the lanthanum-modified TiO2 were maintained better than the unmodified counterparts at temperatures up to 900°C. As a cleaner energy resource, natural gas provides about 30% energy consumption and more than 27% electricity generation in North America. However, many natural gas reservoirs contain H2S, which needs to be removed by amine scrubbing followed by a Claus process. With pending stricter emission policies and lower commodity prices, it is urgent for natural gas producers to seek more efficient Claus catalysts. In this context, lanthanum-modified TiO2 was tested as a Claus catalyst and a better performance was observed than the unmodified TiO2. We attributed the promoted catalytic activity of La-modified TiO2 to the M3+ cations, which causes oxygen defects in TiO2 and thereby increases SO2 adsorption capacity. A higher SO2 adsorption on the catalytic surface enhances both H2S and CS2 conversion. In addition, sulfate concentrations in the used catalysts were studied to explain the catalytic activities.

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