Re-using of coal-fired fly ash for arsenic vapors in-situ retention before SCR catalyst: Experiments and mechanisms.,Chemosphere

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Re-using of coal-fired fly ash for arsenic vapors in-situ retention before SCR catalyst: Experiments and mechanisms.
Chemosphere ( IF 8.1 ) Pub Date : 2020-04-07 , DOI: 10.1016/j.chemosphere.2020.126700
Shuai Li ₁ , Hongyu Gong ₁ , Hongyun Hu ₁ , Huimin Liu ₁ , Yongda Huang ₁ , Biao Fu ₁ , Linling Wang ₂ , Hong Yao ₁

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Arsenic is easily evaporated with coal combustion, which not only causes serious environmental issues but also leads to the deactivation of selective catalytic reduction (SCR) catalyst. This study focused on the re-using of coal-fired fly ash for arsenic vapors in-situ retention before SCR catalyst in the furnace. Experiments were carried out to estimate the effects of typical fly ash compounds (Ca-, Fe-, and Al-bearing components) as well as acid gases (SO2/NO) on arsenic capture at temperatures of high-temperature furnace stage (900 °C) or SCR system entry stage (450 °C). The results demonstrated that, regardless of collection plants, all the ash samples showed certain capacity in arsenic vapors retention and the capture performance was enhanced at 900 °C than at 450 °C. Both physical and chemical adsorptions occurred for arsenic capture at low temperature, while chemical adsorption by effective mineral components dominated at high temperature. The role of Ca-compounds was more remarkable than Fe/Al-compounds and CaSO4/calcium silicates were identified as the key calcium compounds that acted on arsenic adsorption by fly ash. Insignificant effects were found regarding the acid gases (SO2 and NO) on arsenic retention by fly ash owing to the high resistance of CaSO4 and calcium silicates to acid gases. These findings provided reference for the in-situ retention of arsenic by reusing fly ash that enriched in specific compositions.

中文翻译：

将燃煤粉煤灰重新用于SCR催化剂之前的砷蒸气原位保留：实验和机理。

煤燃烧容易蒸发掉砷，这不仅会导致严重的环境问题，还会导致选择性催化还原（SCR）催化剂失活。这项研究的重点是在煤焦粉煤灰中再利用SCR催化剂之前，将其保留在砷蒸气中。进行实验以评估典型粉煤灰化合物（含Ca，Fe和Al的组分）以及酸性气体（SO2 / NO）对高温炉段温度（900°C）砷捕获的影响C）或SCR系统进入阶段（450°C）。结果表明，无论采用何种收集装置，所有灰分样品均显示出一定的砷蒸气保留能力，并且900°C的捕集性能比450°C的捕集性能提高。低温下砷的捕获同时发生了物理和化学吸附，而在高温下有效矿物成分的化学吸附占主导。Ca化合物的作用比Fe / Al化合物更为显着，CaSO4 /硅酸钙被确定为是粉煤灰对砷吸附的关键钙化合物。由于CaSO4和硅酸钙对酸性气体具有很高的抵抗力，因此发现酸性气体（SO2和NO）对粉煤灰中砷的保留影响不大。这些发现为通过重复利用富含特定成分的粉煤灰原位保留砷提供了参考。Ca化合物的作用比Fe / Al化合物更为显着，CaSO4 /硅酸钙被确定为是粉煤灰对砷吸附的关键钙化合物。由于CaSO4和硅酸钙对酸性气体具有很高的抵抗力，因此发现酸性气体（SO2和NO）对粉煤灰中砷的保留没有显着影响。这些发现为通过重复利用富含特定成分的粉煤灰原位保留砷提供了参考。Ca化合物的作用比Fe / Al化合物更为显着，CaSO4 /硅酸钙被确定为是粉煤灰对砷吸附的关键钙化合物。由于CaSO4和硅酸钙对酸性气体具有很高的抵抗力，因此发现酸性气体（SO2和NO）对粉煤灰中砷的保留影响不大。这些发现为通过重复利用富含特定成分的粉煤灰原位保留砷提供了参考。

更新日期：2020-04-08

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