NH4HSO4强化丝瓜络热解协同联产呋喃与超级电容器用氮掺杂炭研究

NH4HSO4 Enhanced Pyrolysis of Luffa for Synergistic Coproduction of Furans and Nitrogendoped Carbon for Supercapacitors

摘要:

热解是生物质高值化利用的重要途径,但常规热解多以生物油为目标,生物炭仅被视作低值副产品,难以实现原料的全组分高值化利用。丝瓜络富含纤维素和半纤维素,孔隙发达且吸液性强,兼具呋喃类化合物前驱体与多孔炭前驱体的双重属性。据此,本文提出以酸式铵盐NH4HSO4为双功能试剂,强化丝瓜络热解定向制备呋喃类化合物,并将生物炭级联转化为氮掺杂超级电容器炭材料。对比了4种负载盐的催化作用,并系统考察了NH4HSO4负载量与热解温度的影响。结果表明, NH4HSO4的强酸性及其在350℃下仍保有的焦硫酸铵(NH4)2S2O7活性组分为丝瓜络热解提供丰富的酸性位点,促进糖类脱水,异构化生成呋喃类化合物。在NH4HSO4/丝瓜络质量比1∶1、温度350℃的条件下,呋喃类化合物(FF+5-MF)产率达3.27%。所得生物炭经活化后,比表面积由511.1m2/g大幅提升至2009.7m2/g,氮含量由0.88%提高至5.74% ,并且在1A/g下比电容提升约90.9% ,达212.1F/g,10A/g下电容保持率为76.1%。

Abstract:

Pyrolysis was considered as a key approach for high-value utilization of biomass; however, conventional pyrolysis was primarily targeted at bio-oil, while biochar was regarded merely as a low-value byproduct, which made full-component valorization of feedstocks difficult to achieve. Luffa sponge was found to be rich in cellulose and hemicellulose, possessed well-developed pores and strong liquid absorption capacity, and exhibited dual characteristics as both a precursor for furan compounds and a porous carbon material. Based on this, ammonium bisulfate (NH4HSO4) was proposed as a bifunctional reagent to enhance the selective production of furan compounds during luffa sponge pyrolysis, which was followed by the cascading transformation of the resulting biochar into nitrogen-doped supercapacitor carbon materials. The catalytic effects of four different salt loadings were compared, and the influences of NH4HSO4 loading ratio and pyrolysis temperature were systematically investigated. The results showed that abundant acidic sites were provided during luffa sponge pyrolysis by the strong acidity of NH4HSO4 and its retained active component—ammonium pyrosulfate ((NH4) 2S2O7)—at 350℃, which promoted the dehydration and isomerization of sugars to generate furan compounds. Under conditions of an NH4HSO4/luffa sponge mass ratio of 1∶1 and a pyrolysis temperature of 350℃, a furan compound (FF+5-MF) yield of 3.27% was achieved. After activation, the specific surface area of the obtained biochar was significantly increased from 511.1m2/g to 2009.7m2/g, and the nitrogen content was raised from 0.88% to 5.74%. Furthermore, the specific capacitance was improved by approximately 90.9% to 212.1F/g at 1A/g, and a capacitance retention rate of 76.1% was obtained at 10A/g.