| Summary: | 博士 === 國立臺灣科技大學 === 化學工程系 === 100 === Solid solution material has long attracted the interest of scientists due to its versatile applications. General preparative method is to heat particles directly (usually > 1000 °C) in micro scale. The loss of surface area by sintering limits the applications of solid solution materials. Several engineering methods are proposed and studied: morphology engineering is used to increase the surface area; dispersion engineering is used to manufacture materials with high catalytic activity and oxygen vacancy engineering is used to create more oxygen vacancies. It is hoped that these engineering methods can expand the solid solution material’s applications.
By means of the morphology engineering, rod-like Cu-Fe solid-oxide material with nano-size ~ 9 nm (crystal size) and 126 m2/g BET surface area has been synthesized. CuO and Fe2O3 phases change to spinel CuFe2O4 structure at 750 °C, whereas a calcination temperature above 1000 °C is usually required in the common preparative method (> 1μm crystal size and < 0.3 m2/g). Cu nanoparticles (~3.6 nm crystal size) are generated from the rod-like solid solution by the dispersion engineering. This catalyst clearly outperforms commercial G66B in conversion for the steam reforming of methanol.
Rod-like CuCe solid oxides are synthesized by the same engineering method. The obtained solid oxides have about 9 nm crystal size and 109 m2/g BET surface area. The dispersion engineering helps to generate Cu nanoparticles (~2 nm by N2O method). The sample was benchmarked with Cu-SBA-15 of the same composition by sol-gel method. In XAS, both samples have similar coordination number and are confirmed with no oxidation state Cu after reduction. It is found that there is evidence of electronic transfer from CeO2 to Cu in rod-like CuCe, where higher electron occupancy of Cu is beneficial high SRM conversion.
The oxygen vacancy engineering is developed to create more oxygen vacancies in ceria oxide. The rod-like SmCe solid oxides have nano-size ~ 9 nm (crystal size) and 118 m2/g BET surface area. This material absorbs CO2 at 50 °C and is able to convert CO2 to CO above 300 °C.
These engineering methods significantly improve the general preparative methods to produce nanoparticles and expand the horizons of solid solution materials and their applications. Finally, the patent of fluid separation technology is invented in appendix.
|
|---|
