Capture of arsenic in coal combustion flue gas at high temperature in the presence of CaSiO3 with good anti-sintering

Abstract

Arsenic with high volatility and toxicity is usually generated during coal combustion and the capture of arsenic is restrained at high temperature since the sintering of adsorbents. Therefore, it is necessary to develop an adsorbent with sintering resistance for the arsenic removal at high temperature. In the study, the arsenic vapor capture by CaSiO3, CaO and SiO2 was carried out in the flue gas with/without SO2 and NO at high temperatures from 1000 °C to 1200 °C. The results showed that CaSiO3 exhibited excellent arsenic capture with the capacity of 4.98 mg/g and the capture efficiency was increased with the temperature increasing. The effect of acid gases was also considered. A certain amount of CaSO4 with poor capture performance was formed on CaSiO3 surface in the presence of SO2, leading to the decrease of the amount of arsenic captured. On the other hand, the effect of NO was not obvious as SO2. Although arsenic capture was suppressed when introduced SO2 and NO, it still remained considerable arsenic capture for the CaSiO3 adsorbent. Additionally, the pivotal role of O2 was also studied. Taking into account the high capture capacity and excellent anti-sintering property, CaSiO3 was a good adsorbent suitable for the removal of arsenic from coal combustion flue gas.