V_2O_5/ACF low-temperature selective catalytic reduction catalyst and mechanism of removal of NO

Title: V_2O_5/ACF low-temperature selective catalytic reduction catalyst and mechanism of removal of NO Author: Lu Zhengyang Degree-granting unit: Zhejiang University Keywords: V_2O_5/ACF;; NO;; SCR;; doping;; catalytic properties Summary:

China's coal-fired thermal power plants currently based, coal-fired emissions of NOX in the atmosphere to form acid rain and photochemical smog on the environment and cause serious damage to the human body, and thus to control and eliminate the flue gas NOX become an urgent requirement . At present the most valuable method is applied ammonia rare earth magnets selective catalytic reduction (SCR) technology. Purpose of this paper is to seek an efficient purification of NO, has a strong sulfur tolerance and life-long low-temperature selective catalytic reduction catalyst, and its performance and the removal mechanism of systematic research.

This paper uses an equal volume impregnation of V_2O_5/ACF temperature selective catalytic reduction (SCR) catalyst. The first blank ACF modified with concentrated nitric acid oxidation, and oxidation to acid modified ACF as the carrier, the load of ammonium metavanadate, and other active substances. On the preparation of the catalyst activity test, examining the amount of active substance load, temperature, reactant inlet concentration, the proportion of ammonia nitrogen, oxygen and other factors affecting the efficiency of denitrification, and to study the system after the introduction of 500ppm SO_2 catalyst sulfur tolerance. Experiments show that: in keeping NH3, NO volume ratio of 1.1, the volume composition of 1000 × 10-6NO, 1000 × 10-6NH3, 5% O_2 and the carrier gas N_2, temperature 180 ℃, 1.0 g catalyst V_2O_5/ACF quality conditions Next, 7% V_2O_5 / ACF catalyst has the best denitrification activity, denitrification rate can reach 52% and there is strong anti-poisoning ability SO_2, denitrification rate was 52% when SO_2 never dropped to 50%.

To improve V_2O_5/ACF denitrification rate and improve the stability and catalyst life, a better catalyst in the selected 7% V_2O_5/ACF catalyst on the basis of doping. Since Mn has a low-temperature high denitrification performance but poor performance characteristics of sulfur, and sulfur tolerance of 7% V_2O_5/ACF strong combination of catalysts prepared by low-temperature catalyst. For the preparation of a series of 7% V-(x) Mn / ACF catalyst activity test, and the introduction of the anti-sulfur performance 500ppmSO_2 study. The results showed that: in the reaction conditions to maintain NH_3, NO volume ratio of 1.1, the volume composition of 1000 × 10-6 NO, 1000 × 10-6 NH_3, 5% O_2 and the carrier gas N2, the temperature 180 ℃, catalyst 7% V_2O_5-( x) Mn / ACF mass of 1.0 g of conditions, 7% V-3% Mn / ACF has the best denitrification rate reached 69.5%, and in a 500ppm SO_2 when the denitrification rate can reach 62%, showing a strong resistance to sulfur poisoning properties to achieve a strong and efficient low-temperature catalyst sulfur tolerance. In http://www.chinamagnets.biz/ addition, taking into account V_2O_5/ACF stability and life is not high, and has good stability properties of rare earth elements, on the 7% V_2O_5 / ACF catalyst rare earth elements (Ce and Zr) doped. Experimental results show that: 7% V-5% Ce / ACF has better catalytic denitrification stability. Denitrification in the 0-600 min period when the rate began to stabilize from 58% fluctuation to 54% lower than the undoped Ce, 7% V_2O_5/ACF (fluctuations from 52% to 43%) more stable. To achieve high stability and strong low-temperature catalyst.

Of the catalyst BET surface area analysis, thermal gravimetric analysis (TG), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), etc. experiments to grasping the catalyst physical characteristics and chemical properties, can be a catalyst catalytic NO data findings provide experimental support and verify the activity of the test findings, but also for catalyst development and improvement and the denitrification reaction may be the mechanism to provide guidance. Degree Year: 2010