PdCo/SiO_(2)双金属催化剂用于杂环储氢载体的高效脱氢

Employing PdCo/SiO_(2) catalyst in high activity dehydrogenation reaction of heterocyclic H_(2) storage carrier

乙基咔唑/十二氢乙基咔唑(N-ethylcarbazole/dodecahydro-N-ethylcarbazole,NECZ/12H-NECZ)体系被认为在有机液体储氢领域具有较大的开发应用前景,但高活性、选择性的脱氢催化剂的设计开发制约着其工业应用。基于此,设计开发出一种具有高脱氢活性和高选择性的双金属催化剂Pd_(1)Co_(3)/SiO_(2)(Pd质量分数为1.25%),对其结构进行了XPS、XRD、HRTEM等表征分析,并评价了其催化十二氢乙基咔唑的脱氢性能。与5.0%(质量分数)Pd/SiO_(2)相比,表明引入一定量的Co金属形成的PdCo合金可提高12H-NECZ脱氢反应效率和NECZ选择性,动力学与DFT计算发现双金属催化剂可以有效降低三步基元反应的能垒,大幅提升第二步基元反应(8H-NECZ到4H-NECZ)的脱氢反应速率。研究结果为揭示12H-NECZ脱氢反应机理和高效脱氢反应催化剂的设计与开发提供了新的思路。

N-Ethylcarbazole/dodecahydro-N-ethylcarbazole(NECZ/12H-NECZ)system was regarded as a promising hydrogen storage solution in the liquid organic hydrogen carriers(LOHC)filed.However,the design and development of high activity and selectivity dehydrogenation catalysts still chocked off the industrial application of NECZ/12H-NECZ system.Aiming to improve H_(2) release efficiency of 12H-NECZ,bimetal catalyst Pd_(1)Co_(3)/SiO_(2)(Pd content:1.25%(mass))with high dehydrogenation activity and high dehydrogenation selectivity was synthesized in this work.The structure properties were characterized by XPS,XRD and HRTEM.And its catalytic performance was evaluated in the dehydrogenation reaction of 12H-NECZ.Compared with commercial 5.0%(mass)Pd/SiO_(2),it was indicated that the formation of PdCo alloy by the introducing of metal Co facilitated the dehydrogenation efficiency of 12H-NECZ and selectivity of NECZ.Both the reaction kinetics results and DFT calculation analyses showed the obvious decreasing of energy barriers of three elementary reactions by employing bimetal catalyst.Especially in the 2ndelementary reaction(8H-NECZ to 4H-NECZ),its efficiency was boosted a lot.The research content in this paper provides new ideas for revealing the mechanism of 12H-NECZ dehydrogenation reaction and designing and developing efficient catalysts for dehydrogenation reaction.