摘要
Ni-P非晶态合金对一氧化碳、苯乙烯和丁二烯加氢具有比晶态合金高的活性和选择性。由于其晶化温度低,在反应过程中逐渐晶化,导致其加氢活性也逐渐下降。将少量Y加入到Ni-P非晶态合金中,不但使Ni-P非晶态合金晶化温度提高147℃,而且使其加氢活性提高3倍左右。未经预处理过程的Ni-Y-P非晶态合金加氢活性较低;依次经过氧化、还原处理,其加氢活性有所上升;最佳的预处理条件是240℃氧化1h,300℃氢气还原2h。但有关预处理过程中,Ni-Y-P非晶态合金表面状态的变化的研究,至今末见文献报导。
Amorphous Ni-Y-P alloy in the form of ribbon ca.2mm wide and 10-20 μm thick was prepared by the vacumm rapid quenching method Using a single Cu foil. In order to prepare the unorphous Ni-Y-P alloy powder, it was heated at 573 K.8MPa of hydrogen for 40 h, and then treated with oxygen and hydrogen. The resulted unbrittled ribbon was ground into the powder sample. After pretreatment with oxygen at 240 ℃ for 1 h, and hydrogen at 300℃ for 2 h, the surface area of Ni was larger and hydrogen desorption energy was smaller than that with other pretreatment condition. The results of AES spectra indicated that without pretreatment, the concentrations of Ni and P in the surface layer were equal to those in the bulk, and that the concentration of Ni on the surface was increased after pretreatment with oxygen and hydrogen. The oxygen and hydrogen pretreatment brought about changes in composition not only in the surface of the amorphous Ni-Y-P alloy but also in its interior. If amorphous Ni-Y-P alloy was treated only with oxygen and without hydrogen, the concentration of Ni on the surface was much lower. TPR results showed that amorphous Ni-Y-P alloy had two reduction processes after oxidation at 240 ℃ for 1 h, oxidized Ni was reduced at 200 ℃, and the Ni-P-O surface species was reduced at 510 ℃. The pretreatment with oxygen and hydrogen not only increased the concentration of Ni in the surface, but also changed the electronic state of Ni.
出处
《分子催化》
EI
CAS
CSCD
1991年第3期272-275,共4页
Journal of Molecular Catalysis(China)
