Preparation And Pilot Application Of Novel SCR Nano-catalysts

With the rapid development of economy, the traditional development model, which is high consumption, emission and low efficiency, has been unsuitable for the needs of sustainable development. Nitrogen oxides (NOx) are the most poisonous kind of pollutants to the ecology and human health. Thus, many approaches have been investigated to control the emission of NOx. Selective catalytic reduction (SCR) technique has been proven to be one of the most effective methods for NOx reduction. The remarkable SCR technique is to develop economical and practical catalysts at low temperature.The thesis was based on the low temperature SCR catalyst developed by the research team. In this thesis, we prepared a series of catalysts through sol-gel method and examined their catalytic performance for NOx removal. Firstly, great promotion effect was achieved on introduction of hBN to CuOx/TiO2 catalyst. Secondly, the doped of Fe could adjust the catalyst active temperature window and improve the catalytic performance. Thirdly, the pilot application of catalyst at low temperature also has been studied.(1) The introduction of hexagonal boron nitride (hBN) to CuOx/TiO2 catalyst could greatly promote the SCR performance.10 wt% addition of hBN achieved the best activity with the removal efficiency of 90.6% at 275℃. The specific surface, oxidation of NO to NO2 and adsorption of NOx were improved with the introduction of hBN. Moreover, the regeneration of catalyst deactivation caused by SO2 could be achieved by heating the catalyst in N2 at 300℃. Our study indicates that hBN can also be used as SCR catalyst promoter similar to carbonaceous materials.(2) Fe was introduced to catalyst with sol-gel method and was proved to be effective to promote the NH3-SCR activity. The change of Fe/Cu ratio can adjust the active temperature windows and increase the specific surface. Among them, the catalysts of Fe10Ti85BN5, Fe3Cu1Ti85BN5 and Fe1Cu3Ti85BN5 achieved best performance at high temperatures, middle temperatures and low temperatures, respectively. This could be a guidance to design the catalyst formula for flue gas at different temperature.(3) Due to the reaction of NO2 and ammonium sulfate, NO2 can effectively suppress the poison of catalyst caused by SO2. This invention can extend the life and decrease the cost of SCR catalyst.(4) Considering the cost, the catalyst was prepared by impregnation method, and the activity test and pilot application have been conducted. When the velocity of flue gas is 8 m/s, NOx removal efficiency is about 38% at 200℃ with 0.5m catalyst module, when converted to standard industrial module (2m), the efficiency is about 85%.