摘要
丁二烯选择性加氢是提升碳四综合利用效率的关键技术,因此受到了工业界和学术界的广泛关注.然而,在实际操作过程中,原料中的单烯烃也可能发生加氢,这降低了整个工艺过程的经济性.此外,丁二烯分子内含有两个共轭的C=C双键,其化学性质活泼,容易在金属催化剂表面发生聚合生成碳沉积物,从而导致催化剂失活.因此,如何提高烯烃的选择性和催化剂的稳定性成为一项挑战.目前,丁二烯加氢反应主要采用Pd,Pt,Au等贵金属催化剂,但贵金属的高昂价格和稀缺性限制了其大规模应用.因此,开发基于廉价金属的替代催化剂具有重要意义.镍基体系在丁二烯的选择性加氢中显示出一定潜力,然而,其实际应用受到积炭和过度加氢导致的严重失活等问题的影响.本文在前期工作固相法合成Ni_(3)ZnC_(0.7)@C(采用无溶剂的固态反应法合成,将金属硝酸盐与双氰胺机械混合,再于氢气下高温还原制得,其中Ni_(3)ZnC_(0.7)颗粒外围具有碳层覆盖,详见Dalton Trans.,2023,52,11571–11580)基础上,通过对Ni_(3)ZnC_(0.7)@C进行可控的空气氧化处理去除碳层,设计制备了一种具有双核壳结构的Ni_(3)ZnC_(0.7)@Ni@C新型催化剂.该催化剂的特点是金属镍小团簇均匀分散在中心Ni_(3)ZnC_(0.7)纳米粒子上,而Ni_(3)ZnC_(0.7)@Ni被全部包裹在多孔碳壳中.利用高角度环形暗场扫描透射电子显微镜、高分辨透射电镜、热重分析和Ar离子溅射X射线光电子能谱等技术进行了表征,并提出了氧化过程中催化剂组成与结构的变化规律.实验结果表明,Ni_(3)ZnC_(0.7)@Ni@C催化剂在丁二烯选择性加氢反应中表现出较好的活性和稳定性,其性能超过了Ni_(3)ZnC_(0.7)@C和很多文献报道的镍催化体系,如Ni_(3)InC0.5和Ni_(3)In合金等.此外,本文还发现Ni_(3)ZnC_(0.7)@Ni@C催化剂在初始反应阶段的积炭行为具有自限性.相对于碳载体本身,反应中原位沉积的少量碳质
The pursuit of developing catalysts from earth-abundant materials to supplant those based on precious metals is of paramount importance in selective hydrogenations.While nickel-based systems have shown promise in the selective hydrogenation of butadiene,their practical applications are hampered by severe deactivation issues due to coke deposition and excessive hydrogenation.Here,a novel catalyst,Ni_(3)ZnC_(0.7)@Ni@C,is ingeniously engineered through the controlled oxidation of Ni_(3)ZnC_(0.7)@C.This catalyst is characterized by small Ni0 ensembles elegantly embellishing the Ni_(3)ZnC_(0.7) nanoparticles,all encased within porous carbon shells.The evolutions of this catalyst,in terms of composition and structure during the oxidation process,is meticulously observed and characterized using a spectrum of advanced techniques.The Ni_(3)ZnC_(0.7)@Ni@C catalyst exhibits outstanding activity and stability in the hydrogenation of butadiene,surpassing other Ni-based systems,including its precursor Ni_(3)ZnC_(0.7)@C and other previously documented catalysts such as Ni_(3)InC0.5 and the Ni_(3)In alloy.A pivotal finding of this research is the self-limiting behavior of coke deposition in the initial reaction stages.This intriguing phenomenon not only curbs further deactivation but also significantly enhances butene production,maintaining operational stability for an impressive duration of 80 hours.This discovery underscores the advantageous role of in situ generated'soft'cokes in augmenting the selectivity and stability of the catalyst,which is particularly enlightening for other catalytic processes that are similarly afflicted by coking issues,thereby opening avenues for further in-depth investigations in this field.
作者
陈智冰
陈鑫泰
吕雅丽
牟效玲
范佳辉
李经伟
严丽
林荣和
丁云杰
Zhibing Chen;Xintai Chen;Yali Lv;Xiaoling Mou;Jiahui Fan;Jingwei Li;Li Yan;Ronghe Lin;Yunjie Ding(Hangzhou Institute of Advanced studies,Zhejiang Normal University,Hangzhou 311231,Zhejiang,China;Key Laboratory of the Ministry of Education for Advanced Catalysis Materials,Zhejiang Normal University,Jinhua 321004,Zhejiang,China;Dalian National Laboratory for Clean Energy,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023,Liaoning,China;The State Key Laboratory of Catalysis,Dalian Institute of Chemical Physics,Chinese Academy of Sciences 457 Zhongshan Road,Dalian 116023,Liaoning,China)
基金
国家自然科学基金(22372150)
浙江省自然科学基金(LQ24B030012)
金华市重点科技计划项目(2022-1-078)
浙江师范大学科研基金(ZZ323205020521005039,KYJ51020910,YS304320036).
