A novel gas-solid Micro Fluidized Bed Reaction Analyzer (MFBRA) was developed to deduce reaction rates and kinetic parameters through measuring time-dependent composition changes of evolved gases from the reactions. Application of the MFBRA to the decomposition of CaCO 3 powder resulted in an apparent activation energy of 142.73 kJ/mol and a pre-exponential factor of 399,777 s À1. This apparent activation energy was much lower than the thermogravimetry-measured value of 184.31 kJ/mol, demonstrating a quicker reaction in the MFBRA. This was further verified by CuO reduction in CO, as accelerated by the fast diffusion and high heating rate in the MFBRA. Measurement of pyrolysis of coal and biomass in MFBRA found that the reaction process was completed in about 10 s, a time much shorter than the literaturereported values in larger fluidized bed reactors. By monitoring the release of gas species from reactions at different temperatures, the MFBRA also allowed deeper insight into the mechanism of pyrolysis reactions. V

No abstract

No abstract

To investigate the poisoning effects of the cement dust, the commercial V-based catalyst was directly mixed and aged with the real cement kiln dust. It was found that the introduction of cement dust led to the serious deactivation of catalysts, especially for the aged samples above 300 °C. The multiple characterization results (X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, NH3-temperature-programmed desorption, and H2-temperature-programmed reduction) revealed that the alkaline/alkaline earth metal elements (mainly Ca) can react with the active components through solid-phase reaction to form inactive surface A x V1–x O4 (A=Ca, K, Na, etc.), solid solutions, and the Scheelite phase, bringing about the reduction of the surface acid sites and the passivation of the redox cycle of V5+/V4+. These results implied that the inert solid solutions may form on the industrial flue gas condition, and change the structure and properties of catalytic sites, which may result in the poisoning and inactivation of the selective catalytic reduction catalyst by cement dust.

No abstract