Pt/Al_2O_3与Pt/MgO-Al_2O_3催化剂制备及其催化氢能载体甲基环己烷脱氢反应性能

以碱共沉淀法制备Mg-Al水滑石,然后采用浸渍法负载活性组分Pt,经焙烧、氢气还原得到Pt/Al_2O_3与Pt/Mg O-Al_2O_3催化剂,采用XRD、N2吸附-脱附、FT-IR、H2-TPR和Py-IR等分析Mg O的加入对Pt/Al_2O_3催化剂结构性能的影响,并在甲基环己烷连续脱氢反应中对比两种催化剂活性。结果表明,Pt/Mg O-Al_2O_3催化剂比表面积小于Pt/Al_2O_3催化剂,且表面基本无酸性活性中心,但表现出与Pt/Al_2O_3催化剂相同的脱氢活性。在Pt负载质量分数2%、催化剂用量0.5 g、甲基环己烷0.1 m L·min-1纯样进料和325℃反应10 h后,原料平均转化率79.9%,脱氢产物只有甲苯,对应的产氢速率192.8 mmol·(g-metal·min)-1,表现出优良的脱氢活性。

Preparation of Pt/Al2O3 and Pt/MgO-Al2O3 catalysts and their behaviors in dehydrogenation of methylcyclohexane as a hydrogen energy carrier

Pt/Al₂O₃ and Pt/MgO-Al₂O₃ catalysts were prepared by formation of Mg-Al hydrotalcite by precipitation with alkali followed by impregnation platinum on the hydroxides,calcination and reduction by hydrogen.The effects of introduction of MgO on structural properties of Pt/Al₂O₃ were characterized by XRD,FT-IR,N₂ adsorption-desorption,H₂-TPR and Pyridine-IR.Activity of Pt/Al₂O₃ and Pt/MgO-Al₂O₃ was compared for methylcyclohexane dehydrogenation.The results showed that surface area of Pt/MgO-Al₂O₃ was much lower than that of Pt/Al₂O₃,and there was almost no acidic sites on surface of Pt/MgO-Al₂O₃,but Pt/MgO-Al₂O₃ exhibited similar dehydrogenation activity as Pt/Al₂O₃.Average methylcyclohexane conversion of 79.90%,the selectivity to toluene of 100% and dehydrogenation rate of 192.8 mmol·(g-metal·min)^-1 were attained under the following condition:Pt loading 2wt%,reaction at 325 ℃ for 10 h over 0.5 g catalyst,methylcyclohexane flow rate 0.1 mL·min^-1.