LaFe1-xNix as a Robust Catalytic Oxygen Carrier for Chemical Looping Conversion of Toluene

Chemical looping biomass gasification is a novel technology converting biomass into syngas, and the selection of oxygen carrier is key for efficient tar conversion. The performance of LaFe1-xNix as a robust catalytic oxygen carrier was investigated in the chemical looping conversion of toluene (tar model compound) into syngas in a fixed bed. LaM (M = Fe, Ni, Mn, Co, and Cu) was initially compared to evaluate the effect of transition metal on toluene conversion. LaFe (partial oxidation) and LaNi (catalytic pyrolysis) exhibited better performance in promoting syngas production than other oxygen carriers. Therefore, Ni-substituted ferrite LaFe1-xNix (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) was further developed. The effects of Ni-substitution, steam/carbon ratio (S/C), and temperature on toluene conversion into C1 and H2 were evaluated. Results showed that the synergistic effect of Fe and Ni promoted toluene conversion, improving H2 yield yet with serious carbon deposition. Steam addition promoted toluene steam reforming and carbon gasification. With S/C increasing from 0.8 to 2.0, the C1 and H2 yield increased from 73.9% to 97.5% and from 197.7% to 269.6%, respectively. The elevated temperature favored toluene conversion and C1 yield. LaFe0.6Ni0.4 exhibited strong reactivity stability during toluene conversion at S/C = 1.6 and 900 °C.

RELATIONSHIP BETWEEN MAGNETIC PROPERTIES AND MICROSTRUCTURE OF FERRITES DURING SINTERING IN RADIATION AND RADIATION-THERMAL CONDITIONS

The studies of correlation between magnetic properties and microstructure were conducted on samples of lithium-substituted ferrite, sintered in radiation and radiation-thermal conditions. Radiation-thermal sintering was performed for compacts irradiated with a pulsed electron beam with energy of (1.5–2.0) MeV, beam current per pulse of (0.5-0.9) A, irradiation pulse duration of 500 μs, pulse repetition rate of (5–50) Hz, and compact heating rate of 1000 C/min. Sintering in thermal furnaces (T-sintering) was carried out in a preheated chamber electric furnace. The paper shows that magnetic induction does not depend on the ferrite grain size. In this case, the coercive force is inversely proportional to the grain size and depends on the intragranular porosity of ferrite samples. In contrast to thermal sintering, radiation-thermal sintering does not cause capturing of intergranular voids by growing grains and enhances coagulation of intragranular pores.

Optical Constants of rare-Earth Substituted Ferrite-Type Amorphous Garnets and Nanoscale Garnet-Oxide Layers

Amorphous ferrite-type rare-earth (RE) substituted garnets and garnet-oxide nanocomposite layers are prepared on clear glass substrates by using RF magnetron sputter-deposition process. By using a combination approach employing custom-built spectrum-fitting software in conjunction with Swanepoel’s envelope method, the spectral dispersion function of optical constants and the layer thicknesses are derived accurately from the transmission spectra of the as-deposited samples. The effects of excess metal-oxides added to the base material systems during the co-deposition process are found to affect the refractive index and the optical absorption coefficients of garnet-oxide composites. A number of optical constant datasets are presented, enabling the experimentalists to design nanophotonic or integrated-optics devices employing these functional materials.