碱活化载铜碳纤维的制备及其对CH_(3)SH的高效催化水解去除研究

Preparation of alkali-activated copper-loaded carbon fibers for the efficien catalytic hydrolysis removal of CH_(3)SH

为了克服催化分解甲硫醇(CH_(3)SH)技术操作温度高(>400℃)和副产物浓度高的缺点,本研究通过静电纺丝技术自行制备碳纤维(C-PAN)作为载体合成载铜催化剂(Cu10%/P-CAN),并通过碱(KOH)活化来提升催化剂的活性.研究结果表明Cu10%/P-CAN催化剂在250℃时对CH_(3)SH的转化率仅有90%.经过碱活化的载铜碳纤维催化剂(Cu10%-KOH10%/P-CAN)在250℃时对CH_(3)SH的转化率高于98%,产物中H_(2)S、COS及CH_(3)SCH_(3)等产物的浓度低于0.0004%.进一步分析表明碱活化处理可以改善活性组分CuO在C-PAN载体表面的分散度,同时提升催化剂表面的碱性位点数量、氧空穴丰度以及活性氧浓度,这是碱活化提升催化剂活性的主要原因.此外,在催化水解CH_(3)SH的过程中,Cu10%-KOH10%/P-CAN把CH_(3)SH中的大部分S元素转化成SO_(4)^(2-),因此减少了产物中含硫气体的产生和避免了二次污染.而催化剂表面硫酸盐的累积和羟基的消耗是催化剂活性衰减的主要原因.

High temperature(>400℃)and high concentration of by-products are major shortcomings in the catalytic decomposition of methyl mercaptan(CH_(3)SH).In this study,carbon fibers(C-PAN)were prepared as carriers by electrospinning to synthesize copper-loaded catalysts(Cu10%/P-CAN),and subsequently activated by alkali(KOH)to enhance the performance of the catalyst.The results showed that the conversion of CH_(3)SH over Cu10%/P-CAN was only 90%at 250℃.The alkali-activated copper-loaded carbon fiber catalyst(Cu10%-KOH10%/P-CAN)had a conversion of CH_(3)SH above 98%at 250℃,and the concentration of H_(2)S,COS,and CH_(3)SCH_(3) in the product was less than 0.0004%.Further analysis showed that alkali activation could improve the dispersion of the active component CuO on the surface of C-PAN,as well as increase the number of basic sites,the abundance of oxygen vacancies,and the concentration of active oxygen on the catalyst surface,which explains the improvement in the catalyst activity by alkali activation.In addition,during the catalytic hydrolysis of CH_(3)SH,Cu10%-KOH10%/P-CAN could convert most of the S element in CH_(3)SH into SO_(4)^(2-),thus reducing the generation of sulfur-containing gas in the product and avoiding secondary pollution.The accumulation of sulfate on the catalyst surface and the consumption of hydroxyl groups are the main reasons for the decay of catalyst activity.