摘要: In the present work, the synergistic effect of components on the mineral behavior in the SiO2-Al2O3-CaO-FeOx quaternary system was tentatively evaluated. The mineral transformation and reaction were analyzed by thermo-mechanical analyzer (TMA), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and thermodynamic calculation (FactSage). In addition, the apparent viscosities of synthetic slags, expressed as a function of temperature and composition, were determined using a high temperature rotary viscometer with temperature ranging from 1 700℃ to re-solidifying temperature. The results demonstrated that the TMA and DSC approaches were applicable to characterize the mineral behavior under in-situ conditions. Silica and alumina preferred to be transformed to high temperature cristobalite and α-alumina with relatively stable structure and high viscosity, respectively. On the other hand, the reaction and transformation of silica and alumina could be accelerated by some valuable fluxing agents, particularly calcium oxide and iron oxides. The addition of ferrous oxide into synthetic slags could lower its viscosity compared with that of ferric oxide and ferroferric oxide. Furthermore, the reduction of iron oxides to metallic iron remarkably increased the viscosity. Ferric oxide may take part in the random glass network in a similar fashion with alumina. Besides, iron oxides with the oxidation state of Fe2+ may also act as a modifier under slightly reducing conditions and higher temperatures. The sensitivity of viscosity of mineral matters to temperature excursion decreased with increasing calcium oxide content as calcium oxide was able to enhance the solution ability of iron oxides in the SiO2-Al2O3-CaO-FeOx quaternary system.
摘要: The combustion reactivity of two chars prepared from two low-rank coals in Northwest China were studied using a thermogravimetric analyzer (TGA). The effects of different atmospheres (O2/CO2, O2/N2 and O2/Ar) and different oxygen concentrations on the combustion characteristics were investigated. The results indicate that both atmosphere and oxygen concentration show effectiveness on combustion of char. Compared with N2 and Ar, CO2 could significantly promote the reaction. When combustion atmosphere changes from O2/CO2 to O2/Ar, the burnout temperature increases by 63.7 and 68.8℃ for the two chars respectively. Meanwhile, when the combustion atmosphere changes from O2/CO2 to O2/N2, that is 135.9 and 129.6℃, respectively. An increase in concentration of oxygen can also improve the combustion performance of chars in the test. At the same time, kinetic analysis of the combustion profiles of the chars reveals that both the apparent activation energy E and the pre-exponential factor A increased with increasing oxygen concentration and the compensation effect exists between activation energy E and pre-exponential factor A of chars' combustion.
摘要: A series of BiOBr-graphene photocatalysts was synthesized using hydrothermal method, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflection spectroscopy (DRS) and photoluminescence (PL) emission spectroscopy. The photocatalysts were evaluated for photocatalytic oxidative desulfurization of model oil. The optimal temperature, graphene loading and the amount of hydrogen peroxide (H2O2) were investigated. The oxidation reactivity of the different sulfur compounds was found to be in the order of DBT>4, 6-DMDBT>BT. Moreover, the mechanism of photocatalytic oxidation of DBT by BiOBr-graphene was proposed based on the present experimental results.