【摘要】 本文用程序升温还原(TPR)方法研究了硅铝(SiAl)和铈Y型分子筛(CeHY)催化剂上沉积镍钝化前后的还原情况。发现在TPR图上沉积镍的还原峰温为600～610℃,比一般的NiO要高290～300℃。在Sb钝化剂处理过的催化剂的TPR图上.在5G0～530℃和700℃左右出现二个还原峰。在Sn钝化剂处理过的催化剂的TPR图上,在510～550℃和700～760℃左右也出现二个还原峰。TPR图形的差别表明在沉积镍和钝化剂之间存在强的相互作用。或者形成了合金。TPR的实验结果与以前得到的XRD测量数据完全一致。本文还用电子顺磁共振(ESR)方法研究了沉积镍的还原过程,发现在平衡条件下沉积镍在400～500℃之间开始还原。ESR图谱上有一宽而对称的谱线(g(?)2.160)和一弱的诺线(g(?)1.965),前者相当于金属镍的f.m.r.吸收谱线,后者相当于Ni~+离子的顺磁吸收谱线。700℃还原以后少量Ni~+离子依然存在于催化剂样品中。锑和锡钝化剂处理以后,样品的ESR图谱发生变化。更多还原

【Abstract】 The reduction of nickel deposits on silica-alumina (SiAl) and cerium-ex-changed Y zeolite (CeHY) before and after passivation with antimony and tin compounds has beon studied by means of TPR and ESR methods, TPR results show that the reduction peak of nickel deposit occurrs at 600-610℃, which is 290-300℃ higher than ordinary NiO, After treatment of the deposit with antimony dimethyldithiophosphate, TPR shows two peaks at 500-530℃ and 700℃. After treatment of the nickel deposit with tin dimethyldithiophosphate, TPR again shows two peaks at 510-550℃ and 700-760℃. The changes in TPR profiles indicate that there are strong interactions or alloying between nickel deposit and the antimony and tin compounds. This is in full agreement with the data obtained from XRD measurements in a previous study.ESR data shows that the reduction of nickel deposit on catalysts starts somewhere between 400-500℃ under equilibrium conditions. A broad and symmetrical spectrum (g=2.160) and a weak spectrum (g=1.965) have been observed. The former is ascribed to the f. m. r. absorption of nickel metal and the lancer to the paramagnetic absorption of Ni~+ species. After reduction at 700℃ a trace amount of Ni~+ species still exists in the catalyst. ESR spectrum has changed after treatment with antimony and tin compounds.更多还原