【摘要】 本文以异丙苯裂化为典型反应,利用脉冲微反技术,考察了不同形态的镍沉积对硅铝(SiAl)和铈Y型分子筛(CeHY)催化剂裂化性能的影响.结果说明用硝酸镍沉积时,随着催化剂上镍含量增加,SiAl的裂化初活性下降,而CeHY的裂化初活性上升,用环烷酸镍沉积时,SiAl和CeHY的裂化初活性均是先下降,后上升.沉积镍后650℃水蒸气处理使多数催化剂的裂解活性下降.用TPD方法测量了沉积镍催化剂表面酸中心的变化规律,发现沉积镍以两种不同的方式影响催化剂的表面酸性,并且裂化初活性和表面酸中心数的变化规律是一致的.在某些情况下,当催化剂的部分表面酸位被沉积镍覆盖或消除时,表面酸中心数下降,催化剂裂化活性也下降,在其它情况下,当沉积镍与催化剂发生强烈的相互作用时,催化剂表面酸位增加,裂化活性也增加.实验中还发现硝酸镍沉积以后,CeHY催化剂的稳定性大大下降.本文对此以镍沉积还原后的脱氢性能进行了解释.更多还原

【Abstract】 The effect of nickel deposit on the cracking behavior of silica-alumina(SiAl)and cerium-exchanged Y zeolite(CeHY)was studied in a pulse microreactor using cumene as feedstock.It was found that for nickel deposit from nickel nitrate or nickel naphthenate,the effect on the cracking activity was different for different catalysts.In the case of nickel nitrate,the initial cracking activity of SiAl decreased and that of CeHY increased,when the amount of nickel deposit increased.In the case of nickel naphthenate,however,the initial cracking activity of both SiAl and CeHY catalysts decreased at first and then increased,when the amount of nickel deposit increased,steam treatment of catalysts at 650℃ after nickel deposition caused further deactivation of most catalysts.Surface acidity of the catalysts contaminated with nickel deposits was measured by TPD method.Experimental results showed that the surface acidity of catalysts was affected by nickel deposition in two ways:when the surface acid sites on the catalyst were partly covered or eliminated by nickel deposition,the nember of acid sites measured by TPD decreased and the cracking activity was lowered;when a strong interaction took place between the nickel deposit and the catalyst,leading to the reinforcement of surface acid sites,the cracking activity increased.These results were consistent with those of cumene cracking test.It was also observed that the stability of CeHY catalyst decreased significantly after nickel nitrate deposition.This was interpreted in terms of the dehydrogenation characteristics of the nickel deposit after reduction.更多还原