Jian Xin Cao

Effect of Calcination Temperature on Mineral Composition of Carbide Slag, Lime Activity and Synthesized Xonotlite

The calcined carbide slag was used to prepare xonotlite by replacing quicklime as the calcareous materials. Effects of calcination temperature on the mineral composition of the carbide slag, lime activity and synthesized xonotlite were studied. The results indicated that carbide slag after proper calcination can be used to prepare xonotlite. Calcination temperature has no effect on the synthesized xonotlite, but has a great impact on lime activity and morphology of secondary particles of xonotlite.

Analysis of Phosphogypsum’s Physical and Chemical Properties and Making of Anhydrite Cement from Phosphogypsum

The phosphogypsum (PG) sample produced as the waste of the phosphoric acid fertilizer plant from Guizhou, China was studied for its properties and as a material for anhydrite cement. The impurity content, type and distribution, as well as thermal behavior and solubility of the PG were carefully studied by XRD, DTA techniques and gravimetric determination. The China Standard GB175-2007. The mineralogical studies were physical properties of the sample were studied as per the determined by XRD. The results showed that the impurities of PG are mainly water-soluble P2O5, F, organics and P2O5 and F in the gypsum lattice which has entered in to solid solution with gypsum as well as the insoluble Ca3(PO4)2 and CaF2. Experimental datum showed that a suitable anhydrite can be produced by heating PG at 1000 °C and PG up to 60% used can be as a main raw material in production of anhydrite cement.

Hydrothermal Synthesis of Xonotlite Fibers and Investigation on their Thermal Property

A hydrothermal route for preparing large size xonotlite fibers without special instruments and synthesis conditions was development. Effect of pH values in system on the crystal phase and morphology of synthesized xonotlite fibers was studied by using XRD and SEM. The results indicated that the different pH systems have little effect on the crystallinity of synthesized xonotlite, but have great impact on the morphology of xonotlite fibers. The higher pH value is, the lager scale xonotlite fibers appear when the pH values are among 12.0, 12.5, 13.0 and 13.5. The formation of xonotlite fibers was promoted and xonotlite fibers with 10-30 μm in length and 100-200 nm in diameter were prepared at 220 °C for 15 h in the system of pH 13.5. The evaluation of thermal property revealed that synthesized fibers were excellent in thermal stability at high temperature, and could be potential candidate as reinforcement reagents in composite areas.

Effect of the Ratio of Silica Source on Ultra-Light Calcium Silicate Material In Situ Strengthened with Xonotlite Whiskers

The ultra-light calcium silicate material was reinforced with the method of xonotlite whisker in-situ growth via hydrothermal synthesis. Effects of different ratios of silica sources on microstructure and mechanical properties of the reinforcement were studied in this paper. The results indicated that the ratios of silica sources posed great impacts on microstructure and mechanical properties of the reinforcement. The reinforcement with density of 118 Kg•m-3, flexural strength of 0.42 MPa and compressive strength of 0.66 MPa was successfully prepared under the condition of K2SiO3:H2SiO3 (mol) =2:1.

Effect of Hydrothermal Process on Xonotlite Crystal

Effect of hydrothermal process on xonotlite crystal prepared from K2SiO3 and H2SiO3 respectively in CaO-SiO2-H2O system was researched in this paper. The crystal phase composition and morphology of the xonotlite crystal were analyzed using XRD and techniques. The results indicate that different hydrothermal process poses significant impact on the microstructure of xonotlite crystal. The xonotlite spherical particle with the diameter of 10-20 µm was prepared from H2SiO3 only via dynamic hydrothermal process. The xonotlite whisker prepared from K2SiO3 with the length of 20-40 μm, diameter of 400 nm and the aspect ratio of 50-100 was successfully prepared from K2SiO3 via dynamic hydrothermal process, while with the length of 5-10 μm, diameter of 500 nm and the aspect ratio of 10-20 via static hydrothermal process.

Preparation and Characterization of Nanometer Iron Oxide by Sol-Gel Method and Supercritical Fluid Drying Technology

Iron oxide nanometer powders were prepared by using sol-gel method and the supercritical fluid drying technology (SCFD) from inorganic salts. The characteristics of the iron oxide nanometer powders were characterized systematically. The results showed that the drying and crystallization of the production could be achieved in one step by SCFD method; furthermore, a highly dispersed, size uniformed and with better crystallization magnetite (Fe3O4) nanoparticles can be obtained. Phase transformation of the as-synthesized powders occurs at about 80°C, and only hematite (α-Fe2O3) can be obtained when being heated at temperatures higher than 400°C. The production synthesized by SCFD exhibits significant magnetic properties. As the heat-treated temperature increase, the magnetic properties of the sample decrease gradually.

Synthesis of Light Olefins from CO2 Hydrogenation on Fe/ZSM-5 Catalyst

A Fe/ZSM-5 catalyst was prepared by impregnation method and evaluated in the synthesis of light olefins from CO2 hydrogenation. It is found that The conversion of CO2, the yield of light olefins and hydrocarbons content reach 82.42%, 12.65%, 0.4885mol respectively under the conditions as follow, mass concentration of ferric nitrate 9%, silica to alumina ratio 25, calcination temperature of the catalyst 500°C. By the studies of NH3 temperature programmed desorption, performance changes of the catalysts was analysis. A possible mechanism is proposed on the basis of mineral composition changes of Fe/ZSM-5 catalyst in the synthesis of light olefins through XRD analysis.

Influence of Hydrothermal Conditions on Ultra-Light Calcium Silicate Material In Situ Strengthened with Xonotlite Whiskers

The ultra-light calcium silicate material was reinforced with the method of xonotlite whisker in-situ growth via hydrothermal synthesis. Effects of different hydrothermal temperatures and reaction times on the microstructure and physical properties of the reinforcement were studied in this paper. The results indicated that the hydrothermal temperatures and times posed great impacts on microstructure of the reinforcement. The increase of hydrothermal temperature and time was beneficial to the growth of xonotlite crystal. The effect of buffer and transfer action of the xonotlite whiskers was the key to reinforcing the ultra-light calcium silicate material.

Influence of Parameters on Catalytic Performance over Different Modified ZSM-5 Zeolite for the IMTO Process

The methanol to olefin with iodide method (IMTO) is a potential and alternative route for its mild process conditions, which produces methyl iodide as intermediate. Methanol can be highly converted, yielding high rates of selectivity to light olefins, by its reaction over varies modified ZSM-5 zeolites. Efforts have been taken to optimize the reaction with respect to selectivity of olefin and conversion of methanol. Based on the analysis of gas chromatography, the following operating conditions were obtained: 250 °C of reaction temperature, CH3OH:HI:H2O=1:1:3 of the molar ratio of raw materials, 2.5 h-1 of methanol space velocity and 30 ml•min-1 of nitrogen low rate.

Effect of Fe Loading Content on Catalytic Performance of ZSM-5 for the IMTO Process

Among the processes for production of olefins, methanol converted to light olefins with methyl iodide as intermediate is a potential and an alternative route, which can be realized under mild condition. ZSM-5 catalyst is considered to be an effective catalyst for methanol to light olefins, better performances for olefins can be obtained by modifying. In this paper, the methanol to olefin with iodide reaction (IMTO) has been studied in a small scale fixed bed reactor over Fe modified ZSM-5 catalyst. It is indicated that ZSM-5 zeolites were modified with Fe loadings successfully, as a result the pore sizes reduced availably comparing with ZSM-5, the conversion of methanol and selectivity of light olefins got 98.8% and 89.5% respectively when modified with 9% Fe loadings.