Yali Wang

Influence of Synthesis Temperature on MnOx/TiO 2 SCR DENOx Catalyst Prepared with Acidolysis Residue

This paper focused on MnOx/TiO2 SCR DENOx catalytic materials prepared with acidolysis residue (a solid waste which was generated during the sulfate process of the titanium oxide industry), and investigated the influence of synthesis temperature on catalytic properties and microstructure of the catalytic materials. Two different synthesis temperatures including ambient temperature and 80 ℃ were employed to prepare the catalytic materials. The modifications of textural, surface properties and catalytic activity of catalyst prepared at different temperatures were compared. Results showed that the catalyst prepared by precipitation method at room temperature (ammonia-hydrogen peroxide was used as precipitant and the calcination temperature is 250 ℃), leads to a higher NOx conversion rate. The NOx conversion at 100 ℃ is 80%, even 95% at 130 ℃. Results from XRD analysis indicate that the catalyst synthesized at room temperature results in a less sharp peak of Mn3O4. The active substances of manganese oxides are highly dispersed on the surface of the catalytic materials in amorphous state. Furthermore, H2-TPR demonstrates that the catalyst synthesized at room temperature has a higher redox activity and the MnO2 phase occupies the leading position of MnOx, which contributes to the excellent NOx conversion rate of the catalytic.

The Influence of Volume Changes in Portland and Calcium Sulfoaluminate Binary Cement

The long-term volume changes of Portland-Calcium sulfoaluminate cement systems has been studied for samples cured under different conditions. Three curing conditions were chosen in this study and the composite cement systems showed different results with different CSA dosages. Progressively higher amount of CSA was added to the composite cement system and it was found that there was a critical dosage of CSA leading to unstable expansion and failure of the samples by curing under water. But in drying condition, the systems showed shrinkage and the degree of volume changes were similar than expansion by curing under water. By selecting the composition of CSA-PC systems and curing conditions, the volume stability of composite cement could be controlled.

Preparation of Micro-porous Chitosan Membrane and Its Adsorption Property for Cr(VI) Ions

Chitosan (CS) micro-porous membranes were prepared by blending-phase inversion method using chitosan as film-forming polymer, polyethylene glycol (PEG) as porogen and glycerol as plasticizer. Adsorption experiments were conducted under varied Cr(VI) ions concentration, pH values, contact time and temperature. The results indicated that when the ratio of chitosan to polyethylene glycol and glycerol was 1:0.5:0.5 at pH of 2.79, the prepared CS membrane exhibited the highest adsorption capacity of 168.41 mg g−1 under Cr(VI) ions concentration of 100 mg L−1, contact time of 4 h, and membrane dosage of 10.0 mg. Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms at different Cr(VI) ions concentrations. The equilibrium data was found to be fitted well to the Langmuir isotherm. Pseudo-first-order and pseudo-second-order kinetics models were used to describe the membrane adsorption.

Influence of characteristics of alumina-silicate raw materials on the formation process of clinker

The traditional alumina-silicate raw materials, for example, clays, in the precalcining technique of cement production, have been replaced by low grade and high silica content sandstones, shales, and industrial waste residues, including fly ashes, slag, and others. The results are the change of compositions and characteristics of raw materials applied and a great effect on cement calcination process and clinker formation. In this work, the cement clinker formation process of different alumina-silicate raw materials to replace clay raw material was studied by chemical analysis, X-ray diffraction, differential thermal analysis, and high temperature microscope based on the characteristics of the alumina-silicate raw materials. The formation heat of the clinker was determined by the acid dissolution method. Influence of different alumina-silicate raw materials on the clinker burnability and formation process was studied. The results show that the changing of alumina-silicate raw materials, especially using industrial waste residues, can reduce the formation temperature of high temperature liquid phases, improve the burnability of raw materials, reduce the formation temperature and formation heat of clinker. And this study also observed the formation temperature and transformation of high temperature liquid phases in the heating process of raw materials by high temperature microscope.