Hydrogen production via methane dry reforming process over CoAl and CoMgAl-Hydrotalcite derived catalysts

Co0.67Al0.31 and Co0.14Mg0.54Al0.31 hydrotalcite based catalysts were prepared by a co-precipitation method at a fixed pH=11, exhibiting a suitable hydrotalcite structure to be used as a catalyst in the reaction of the dry reforming of methane (DRM). Calcination at 450 °C provides the best conditions to prepare the most adapted structure and morphology to be later used in the DRM reaction. The samples were characterised by XRD, FTIR, SEM and it was shown that they exhibit a specific surface in the 30-70 g/cm2 and a crystallite size of approximately 20 nm. The results of the TPR analysis showed clearly that CoAl-HT has better catalytic performances than CoMgAl-HT. This result can be explained by the presence of the Co0 for the catalyst CoAl-HTc-R and the total absence in the sample CoMgAl-HTc-R. The solid CoMgAl-HTc-R requires high reduction temperature compared to CoAl-HTc-R due to the strong CoO-MgO interactions.

Investigation of CuMnOx spinel catalyst for toluene oxidation

CuMnOx spinel catalyst, prepared by the sol-gel method, and characterized by modern techniques such as XRD, BET, H2-TPR, EPR, were used to oxide toluene in the temperature range from 150oC to 400oC . Among, the investigated catalysts as MnO2, CuO, and CuMnOx, the CuMnOx showed the highest catalytic activity. It converted 100% toluene to CO2 at 250oC in excessed oxygen conditions. The higher catalytic performance of CuMnOx than MnO2, CuO because of its higher specific surface area and its lower reduction temperature. The results also implied that the interaction between Cu and Mn could improve the reduction capacity of CuMnOx catalyst. In summary, the CuMnOx catalyst is a promising catalyst for toluene treatment.

SILICOTHERMIC REDUCTION OF THANHHOA DOLOMITE: THERMODYNAMIC AND EXPERIMENTAL

Thermodynamic and experimental studies was carried out on the process of Thanhhoa dolomite reduction to produce magnesium. Thermodynamically studied on the effect of pressure and temperature on reduction was carried out together with verification experiment. Results show that at appropriate temperature and vacuum pressure, Thanhhoa dolomite can be reduced using ferrosilicon as the reductant. The higher level of vacuum, the lower temperature required for reduction. Thermodynamic calculation pointed out that at a vacuum pressure of 600 Pa, the reduction temperature could be as low as 1140 °C. Experiment results indicated that at although reduction could be done at 1150 °C, the process efficiency was low, generally below 20%. Process efficiency enhanced as temperature increase and reaches the highest value of 85,8% at 1250 °C (25 wt.% ferrosilicon). The amount of ferrosilicon used also has influenced the process efficiency. After three hours of reduction, the obtained magnesium was very high in purity, 99.3%.

A Kinetic Study on the Reduction of Single Magnetite Particle with Melting Products at High Temperature Based on Visual and Surface Analytical Techniques

In this study, the reduction characteristics of single magnetite particles with melting products at high temperature were investigated by using visualization and surface analytical techniques. The morphology evolution, product type, reduction degree, and reduction rate of single magnetite particles during the reduction process were analyzed and compared at different reduction temperatures. The results showed that the morphology of the product formed at the reduction temperature of 1300 °C was a mainly nodular structure. When the reduction temperature was above 1400 °C, the products were melted to liquid and flowed out of the particle to form a layered structure. The morphology of the melted products finally transformed to be root-like in structure on the plate around the unmelted core. Raman spectroscopy was used to determine the product types during the reduction process. Experiments studying the effects of gas flowrate and particle size on the reduction degree were carried out, and the results showed that both increasing the temperature and gas flowrate can increase the reduction degree. The internal/external diffusion influence can be ignored with a particle size smaller than 100 μm and a gas flowrate more than 200 mL/min. However, owing to the resistance of the melted products to gas diffusion, the reduction rates at 1400 and 1500 °C were reduced significantly when the reduction degree increased from 0.5 to 1.0. Conversely, the formation of the liquid enlarged the contact area of the reducing gas and solid–liquid and further increased the reduction degree. The kinetics parameters, including average activation energy and pre-exponential factor, were calculated from the experimental data. The reduction kinetics equation of the single magnetite particle, considering the effect of melted products is also given in this study.

Effect of magnesium reduction on the oxygen content of pickling niobium powder

Considering the problem of high oxygen content in industrial niobium powder, the oxygen reduction of high oxygen niobium powder with the addition of magnesium is studied. Based on the thermodynamic analysis of magnesium thermal reduction of niobium powder, the effects of reduction temperature, magnesium addition, reduction time, and reduction atmosphere on the oxygen content of pickling niobium powder are studied. The results show that with an increase in the magnesium addition, the oxygen content of pickling niobium powder gradually decreases to a certain value, and then remains unchanged. In a certain temperature range (953–1203 K), with an increase in the reduction temperature, the oxygen content of pickling niobium powder first decreases, and then increases; the best oxygen content is 356 ppm at 1133 K. With the extension in reduction time (2–6 h), the oxygen content of pickling niobium powder first decreases, and then remains unchanged. Finally, the oxygen content of pickled niobium powder is reduced to approximately 356 ppm at 400% magnesium addition at 1133 K for 4 h.

Effect of Coated Cow Dung on Fluidization Reduction of Fine Iron Ore particles

The effects of reduction temperature, gas linear velocity, reduction pressure, reduction time, and reducing gas on the fluidized ironmaking process were studied for the fine iron Newman ore particles (0.154–0.178 mm) and the optimal experimental operating conditions were obtained. Under the optimal conditions, the effects of the coated cow dung on the reduction of fine iron ore particles were studied, and the inhibition mechanism of cow dung on particle adhesion in the fluidized ironmaking process was elucidated. The experimental results show that the optimal operating parameters are linear velocity of 0.6 m/s, reduction pressure of 0.2 MPa, reduction temperature of 1023 K, H2 as the reducing gas, and reduction time of 60 min. Cow dung can react with oxide in the ore powder to form a high melting point substance that can form a certain isolation layer, inhibit the growth of iron whiskers, and improve the fluidization.