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Acetaldehyde polymerization on Co(0001): the role of CO
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2019-03-11 00:00:00 , DOI: 10.1039/c9cp00441f
Jun Chen 1, 2, 3, 4, 5 , Qing Guo 5, 6, 7, 8, 9 , Jiawei Wu 5, 6, 7, 8 , Dongxu Dai 5, 6, 7, 8 , Maodu Chen 1, 2, 3, 4, 5 , Xueming Yang 5, 6, 7, 8
Affiliation  

The adsorption and polymerization of acetaldehyde (CH3CHO) have been investigated on clean and CO pre-covered Co(0001) surfaces using the temperature programmed desorption (TPD) method. On the clean Co(0001) surface, CH3CHO molecules can polymerize to produce paraldehyde with very low efficiency. With pre-dosed CO molecules on Co(0001), the decomposition of CH3CHO is greatly inhibited. When the coverage of pre-dosed CO is <0.33 ML, no enhancement of CH3CHO polymerization is observed. However, when the pre-dosed CO coverage is >0.33 ML, the polymerization of CH3CHO is significantly enhanced during the TPD process. Further results suggest that CO molecules adsorbed at the bridge/hollow sites may initialize the polymerization by nucleophilic attack of CH3CHO molecules with their O atoms. Moreover, the polymerization product induced by CO molecules is not paraldehyde, but linear polymer chains of CH3CHO at low CH3CHO coverages and probably three dimensional polymer structures at high CH3CHO coverages.

中文翻译:

乙醛在Co(0001)上的聚合反应:CO的作用

使用程序升温脱附(TPD)方法研究了乙醛(CH 3 CHO)在干净的和CO预覆盖的Co(0001)表面上的吸附和聚合。在干净的Co(0001)表面上,CH 3 CHO分子会聚合,以非常低的效率产生对三聚甲醛。通过在Co(0001)上预先添加CO分子,可以极大地抑制CH 3 CHO的分解。当预先加入的CO的覆盖率<0.33ML时,没有观察到CH 3 CHO聚合的增强。但是,当预先添加的CO覆盖率> 0.33 ML时,CH 3的聚合在TPD过程中,CHO显着增强。进一步的结果表明,吸附在桥/空心位点上的CO分子可能会通过CH 3 CHO分子与其O原子的亲核攻击而引发聚合反应。而且,由CO分子诱导的聚合产物不是三聚甲醛,而是低CH 3 CHO覆盖率的CH 3 CHO的线性聚合物链,以及高CH 3 CHO覆盖率的三维聚合物结构。
更新日期:2019-03-11
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