Study on Mid-temperature SCR DeNO x Catalyst under High SO 2 and
1B INTRODUCTION Chinese main energy resource is coal and fire power plant is the primary producer of NOx. With the rapid development of economy, the environmental damage caused by coal-fired becomes more serious. The multiplex acid rain is mainly caused by the emission of SO2 and NOx of coal fire power plants and cement kilns. The Emission Standard of Air Pollutants for Coal-fired Plants implemented at 1st Jan, 2004, has greatly prompted the development of DeNOx industry and the DeNOx industry is becoming a highlight of environmental protecting industry. The SCR technology (Selective Catalytic Reduction) is the most efficient method to control the emission of NOx, which has been widely used in coal-fired plants of developed countries. However, in domestic, the commercial application of DeNOx has just stepped out. The constitutes of coals in China vary drastically, and many coals contain high SO2, high CaO, high ash, and contains of arsenic changes greatly. It is greatly different from the east area coal of America.[1] So far, our country SCR DeNOx equipment have applied alien technology entirely and what’s more, We are short of the experience of pattern selection and operating of catalysts. The core technology of SCR is the systemic design to maintain uniform distribution of smoke and fly ash in reactor. It reported that (NH4)2SO4 and CaSO4 in smoke poisoned catalysts of SCR and reduced the efficiency of DeNOx. Aiming at high SO2 and high CaO ash in coals of China, this paper develops the DeNOx experiments of Mid-temperature SCR catalyst in high SO2 and high CaO condition. The research is a great help for the pattern selection of catalyst in domestic DeNOx industry of coal fired plants.
Characterization and reactivity of V2O5-WO3 supported on TiO2-SO42- catalyst for the SCR reaction
V2O5 and WO3 supported on TiO2-SO42- have been characterized by BET, XRD, XPS, TPD and H-2-TPR measurements. The comparison of the reactivity on SCR reaction of the catalysts with the support allows to understand the interaction of sulfate species with V2O5 and WO3. The sulfate deposited on TiO2 does not affect on its physical properties such as surface area and phase transformation. In TPD and HZ-TPR, it is found that the sulfate stability strongly depends on the loaded metal oxides and the reduction property of V2O5 in ternary sample is changed due to the synergetic effect between V2O5 and WO3. The SCR reactivity of V2O5/TiO2-SO42- at low temperature becomes the same as that of V2O5-WO3/TiO2-SO42-, while at high temperature, the high NO conversion of V2O5-WO3/TiO2-SO42- is extended up to 450 degreesC. Accordingly, it can be suggested that the strong interactions among the supported components on TiO2 play important roles in the modification of the SCR reactivity over TiO2-based catalyst. (C) 2001 Elsevier Science B.V. All rights reserved.
Vanadia supported on titania-silica: physical characterization and activity for the selective reduction on nitric oxide
Abstract Silica-supported titania samples containing between 8 and 34% (w/w) TiO2 were prepared and used as supports to prepare supported vanadia [7% (w/w) V2O5] catalysts for the selective catalytic reduction of nitric oxide. All materials were physically characterized by surface area measurements, UV-VIS diffuse reflectance and Raman spectroscopy and temperature-programmed reduction. The vanadia-containing materials were further characterized by their catalytic activity for the NO + NH3 reaction. The titania-silica preparations contain highly dispersed titania with a tendency to form aggregates with an anatase structure as the titania loading increases. It appears that two types of surface vanadates are being formed, namely a polyvanadate species anchored onto the uncovered SiO2 surface and a second species which is bonded to titania. The catalytic activity of vanadia supported on titania-silica was significantly greater than that of vanadia on silica and increased with titania loading until it reached the theoretical monolayer capacity. A correlation between catalytic activity and concentration of dioxovanadium species was not observed.