Ni—Na—Y型分子筛催化剂上CO2加氢

Ni-Na-Y分子筛对CO_2加氢反应显示出高的CO选择性和低活性。本文用EXAFS、FTIR、EPR和XRD对Ni-Na-Y分子筛进行了表征,结果表明,在H_2还原下首先形成小的Ni原子簇,接着在催化反应过程中粒径变大,并从超笼移向外表面。结果还表明,CO选择性的高低取决于分子筛的酸性、Na~+的存在和Ni原子簇的粒径大小。在CO气氛下的预处理将提高其生成CO的活性和选择性。

HYDROGENATION OF CO_2 ON Ni-Na-Y ZEOLITE

Ni-Na-Y zeolite shows hig(?)CO selectivity.and low activity for the hydrogenation of CO_2.Fhe catalyst has been characterized by EXAFS,FTIR, EPR, FMR and XRD techniques. The results reveal that the small Ni clusters form firstly after pre-reduction in H_2 and then increase their size and move from supercage to external surface during the catalytic reaction.It is also suggested that the high CO selectivity be related to zeolite acidity, the coexistence of Na_+ as well as the Ni cluster size. Prereduction of catalyst in CO atmosphere will further promote both the activity and the selectivity to CO. This could be explained by the relatively small size of well distributed Ni clusters formed in supercage.