Advanced Materials Research Vols. 361-363

Abstract: The formed TiO₂ supports were prepared by compression method and then used in the Pd/TiO2 catalytic hydrogenation of 4-carboxybenzaldehyde (4-CBA). Supports and catalysts were characterized by the intensity test, BET, XRD, SEM and ICP techniques. Results showed that the pore-forming agent can adjust both the specific surface and average pore diameter. The suitable content is 4 wt.%. Silicon additive inhibits the growth of TiO₂ grain and the anatase-rutile phase transformation. Forming pressure brings out a certain crushing strength and pore characteristic. The crushing strength of support significantly increases with increasing support calcination temperature. However, the specific surface and pore volume decrease. The TiO₂ support has the side crushing strength of 122 N/cm and the specific surface of 38 m2/g at the optimum preparation conditions of silicon additive of 4 wt.%, forming pressure of 150 MPa and calcination temperature of 700 °C. A series of Pd/TiO2 catalysts were prepared by incipient wetness of impregnation and liquid-phase chemical reduction method. On Pd/TiO2700 (Pd, 0.5 wt.%) catalyst, the 99.5% conversion of 4-CBA is obtained after reaction for 90 min at reaction temperature of 280 °C and hydrogen partial pressure of 0.6 MPa.

Abstract: Biological treatment of heavy crude oil production wastewater is well-established method for remediation of these wastes. We have developed effective biological treatments by (1) utilizing microbes with high oil-degrading abilities, (2) allowing greater organic loads while increasing both process stability and the resistance to shock loading, (3) minimizing the production of waste sludge byproducts, and (4) adopting anaerobic and aerobic biological processes to improve the biodegradation of the wastewater. Fixed-film bioreactors with 15h hydraulic retention times have decreased chemical oxygen demand by 74.8%, total suspended solids by 90.9%, oil by 80.6%, and phenols and sulfides by 100%. The results with an in situ pilot system show that the bioreactor's hydrolytic acidulation and contact oxidation tanks are suitable for treating oilfield wastewater, and that water quality after treatment fully meets national drainage standards.

Abstract: The effect of concentration, temperature and pH-value on the demulsification potency of the propylene oxide and ethylene oxide block copolymer initiated from alkylphenol formaldehyde resin in breaking up emulsion from Daqing oilfield have been investigated. The results revealed that demulsification potency of the studied demulsifier increases with the increase of demulsifier at low concentration, the increase of temperature, the increase of acidic pH-value and the increase of demulsification time, respectively. In the meantime, demulsification potency of the studied demulsifier decreases with the increase of demulsifier at high concentration and the increase of basic pH-value, respectively. Neutral pH-value of the emulsion was found to be the optimum value causing maximum demulsification potency.

Abstract: The unsteady flow behaviors in devices like gas wave machines, wave rotor refrigerators and so on are complex due to real gas effect at high operational pressure and low temperature. In this work, a detail computational model for unsteady flow analysis of real natural gases is established. The real effect on unsteady behaviors of natural gases in shock tubes have been studied extensively. Results show that the non-classical flow of the gases will not exist. The discipline of reflection and refraction of various gas waves or discontinuities remain unchanged for natural gases. Attention should be paid only to the deviations between perfect gas model and real gas model for gasdynamic waves.

Abstract: A layer of Ni-Cr-Si-B-Fe alloy was successfully coated on plain steel substrate by hot dipping process. The Ni-Cr-Si-B-Fe alloy coating has a homogeneous thickness of 3mm. The chemical composition and microstructure were studied with SEM and XRD in this paper. The result shows that the Ni-Cr-Si-B-Fe alloy coating is defect-free and chemical bonded with plain steel substrate. A light band zone of 8-10 m width is between Ni-Cr-Si-B-Fe alloy coating and plain steel substrate, and may be considered as a quickly solidified layer. The coating microstructure is a heterogeneous microstructure and changes from the light band zone to the surface of the coating, which is composed mainly of coarse columnar dendrite, needle-like precipitates and scattered eutectic structures. Four regions across the thickness of Ni brazing alloy coating, due to solidification conditions upon hot-dipping, have been identified with distinguished microstructure. In γ-(Fe, Ni) solid solution matrix, the hard phases of CrB, Fe₂B and Cr₂₃C₆ is identified in the coating.

Abstract: Copper and cobalt were extracted from nickel chloride solution with N₂₃₅. The various parameters considered in this work were N₂₃₅ concentration, reaction time, phase ratio (O/A) and pH value. The optimum conditions are determined that concentration of N235 in organic phase is 40% (volume fraction), the phase ratio (O/A) is 1:2, pH value is 2~4, chloride concentration is 5.76 mol/L and the reaction time is 4 min. Under the optimized operating conditions, cobalt and copper extracted effectively and the extraction rates at the single stage reached 90% and 97%, respectively. After five stage continuous counter-current process, the concentrations of copper, cobalt, iron in the raffinate are less than 0.0008 g/L，0.008 g/L and 0.0025 g/L, respectively, and the recovery of nickel is higher than 92%. The separation effect is steady and satisfied for the electrolysis.

Abstract: Wet rotating reticular plate electrostatic precipitator gathers the advantages of moving electrode type electrostatic precipitator technology and wet electrostatic precipitator technology, and utilizes reticular plate, which significantly increases the dust collecting area. In this paper, airflow distribution boards were simplified as porous jump model, and empirical equation was used to get the inertial resistance factors of airflow distribution boards. FLUENT was used to simulate the internal flow field under the condition of without guide plates and with guide plates. Regular skewed airflow was formed through introducing guide plates, which improved the internal flow field significantly.

Abstract: High casting speed would change the thermal state of the mould copper plate, The coupled visco-elasto-plastic FEM models have been presented for thermal process analysis of steel shell and the mould copper plates. With the understanding to the mould thermal state for different casting speed, the characters of mould copper plate thermal flux is obtained. It is shown that, the highest thermal flux zone is getting downward with casting speed increasing, and it would also make harder for breakout signals catching.

Abstract: Utilizing Pakistan chromite as raw material, the rapid leaching of chromium and iron could be realized by the sulfuric acid leaching process on the condition of atmospheric pressure and the addition of oxidant A. And the leaching rate of chromium and iron would be 98.5% and 71.9%, respectively. The sulfuric acid leaching processes with different temperature were systematically studied by chemical analysis and phase analysis. The results showed that, with the increase of reaction temperature, the leaching rate of chromium would increase gradually, but the leaching rate of iron increased at first and then decreases and reached its maximum at 140°C. When the temperature > 160°C, the phases of the leaching residue were magnesium iron silicate and a few of silica, no chromohercynite, chrompicotite and magnesioferrite existed in the chromite. The leaching solution of sulfuric acid leaching process could be used for preparing the basic chrome sulfate, and there is no Cr⁶⁺ in the leaching residue and solution. The results would provide theoretical guidance for solving environmental pollution problem of Cr⁶⁺ in traditional chromate production process.

Abstract: High temperature air combustion technology is a new advanced combustion technology, which is energy efficient and has the dual advantages of low pollution emissions and energy conservation. This sustainable development is in line with China’s strategic objectives of energy saving. Based on the high temperature air combustion technology and environmental characteristics, the paper analyzed its heat transfer process and determined the proper commutation cycle based on the numerical model. It is indicated that combustion technology can increase the temperature of air flowing into the furnace, reduce the temperature of the flue gas emissions, and improve thermal and temperature efficiency and thus to save the fuel. It can also suppress the formation of NO_x, reducing CO₂ emissions and is a good environmentally friendly energy technology in industrial furnace.