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利用超声-共沉淀技术制备了一系列EDTA修饰的掺钡纳米氧化镁载体(EDTA-Ba-MgO)及其负载的钌基氨合成催化剂(Ru/EDTA-Ba-MgO)。通过场发射扫描电镜、X射线粉末衍射仪、氮物理吸附、热重分析仪及H_2程序升温还原等方法对载体/催化剂进行表征。结果表明:EDTA的修饰作用改变了钡助剂与载体的作用方式,通过与Ba助剂发生络合作用形成了[Ba(EDTA)]~(2-),改变了Ba~(2+)的带电性质,使钡助剂在带正电荷的载体表面实现了直接吸附,从而更有利于对钡助剂在Ba-MgO中掺杂量及掺杂形式的调控,最终达到提高催化剂活性的目的。在10 MPa,10 000 h~(-1)和698 K的反应条件下,Ru/EDTA-Ba-MgO催化剂上氨合成速率达到69.31 mmol·(g·h)~(-1),比Ru/Ba-MgO提高了7.4%。
A series of EDTA-modified barium-doped nano-magnesia supports (EDTA-Ba-MgO) and Ru / EDTA-Ba-MgO catalysts supported on them were prepared by ultrasound-coprecipitation. The catalysts / catalysts were characterized by field emission scanning electron microscopy, X-ray powder diffraction, nitrogen adsorption, TGA and H 2 temperature-programmed reduction. The results showed that the modification of EDTA changed the mode of action of barium promoter and carrier, formed [Ba (EDTA)] ~ (2-) by complexing with Ba promoter, changed the content of Ba ~ (2+) Charged properties of the barium promoter in the positively charged surface of the carrier to achieve direct adsorption, which is more conducive to the Ba-MgO barium additives doped and doped forms of regulation, and ultimately achieve the purpose of improving the catalyst activity. The ammonia synthesis rate of Ru / EDTA-Ba-MgO catalyst reached 69.31 mmol · g -1 h -1 at 10 MPa, 10 000 h -1 and 698 K, Ba-MgO increased by 7.4%.