Cu/Ce负载对赤泥脱除中低温烟气中NO的促进作用

Promotion of Cu/Ce supported red mud for NO removal from low and medium temperature flue gas

本研究对酸洗赤泥催化剂进行Cu、Ce、Cu/Ce浸渍负载,并研究了金属改性赤泥对烟气中NOx的催化转化性能。研究结果表明,Cu负载催化剂中的Cu+与Cu^(2+),有效促进了赤泥对低温烟气(200–300℃)中的NO转化率,Cu的负载量达到6%时,赤泥的最高NO转化率达到了90.7%;而Ce负载催化剂中的Ce^(3+)与Ce^(4+),有效促进了赤泥对中温烟气(200–400℃)中的NO转化率,Ce的负载量达到8%时,赤泥的最高NO转化率达到了94.0%;Cu/Ce负载催化剂表现出比单金属负载催化剂更好的低温NO转化率,最佳的负载Cu:Ce比例为1∶1,双金属负载催化剂表现出比Cu负载催化剂更好的中温(300–400℃)中的NO转化率,最高达到了95.5%。其原因是,在Cu/Ce协同作用下,Cu+以及Cu^(2+)的还原过程分别从229、302℃降至201以及247℃,同时使发生Fe2O3→FeO的还原过程的温度降低,促使ACRM-Cu1Ce1具有更强的低温氧化还原能力,同时,双金属负载使催化剂具有更高的弱酸性峰,也使催化剂的强、弱酸性峰都向低温偏移,并使负载后的赤泥具有了较高的Fe离子平均氧化态以及较高的Cu+含量,促进了赤泥催化剂对低温NO的转化率。

Red mud is a solid waste in aluminum industry and has been proven to be an efficient alternative to NOx selective catalytic reduction(SCR)catalysts.Acid washing treatment to red mud can improve its alkalinity and surface properties,and increase the conversion rate of NOx.In this paper,Cu,Ce,and Cu/Ce was supported on acid washed red mud and NOx catalytic conversion performance on metal modified red mud catalysts was studied.The research results indicate that Cu+and Cu^(2+)in the Cu supported catalyst effectively promote NO conversion rate of red mud in low-temperature(200−300℃)flue gas,reaching a maximum of 90.7%;Ce^(3+)and Ce^(4+)in Ce supported catalysts effectively promote the NO conversion rate of red mud in flue gas at 200-400℃,reaching a maximum of 94.0%;Cu/Ce supporting exhibits better NO conversion rate than single metal supported catalysts at low-temperatures,the optimal Cu∶Ce ratio for supporting is 1∶1;and also exhibits better NO conversion rate than Cu supported catalysts at high-temperature(300−400℃),reaching a maximum of 95.5%.The reason may be that under the synergistic effect of Cu/Ce,ACRM-Cu1Ce1 has stronger low-temperature redox ability,higher weak acidic peaks,higher average oxidation state of Fe ions,and higher Cu+content.