摘要
选用能对沉积钒和沉积镍的氧化数进行定量表征的程序升温还原(TPR)测试方法,考察了催化裂化催化剂上沉积金属氧化数对降低汽油硫含量的影响.结果表明,V2O3、VO2、V2O5的最终还原产物是VO,催化剂上沉积钒与纯的钒氧化物出现TPR特征峰的温度范围相似;纯NiO易于被还原,而催化剂上沉积镍的TPR特征峰温度明显升高.择效活化处理导致催化剂上的沉积钒氧化数降低.在623～923 K范围内,沉积钒的氧化数随着择效活化温度的增加而降低;923 K时氧化数接近2,基本达到热力学平衡.沉积钒氧化数的降低改变了沉积钒的化学配位效应,有利于形成选择性降低汽油硫含量的活性中心,因而使得催化裂化汽油硫含量下降.当沉积钒的表观氧化数低于3时,催化剂的降硫效果大大提高.
For the further investigation on the desulfurization effect of the oxidation numbers of the vanadium and nickel deposits on FCC catalyst, TPR method was chosen to characterize the oxidation number of metal deposits quantitatively. The results showed that VO was the final reduced product of V2O3, VO2 and V2O5, which can not be reduced further. The temperatures of the TPR peaks of vanadium deposit on catalyst were similar to that of the pure vanadium oxides, but the temperature of the TPR peak of nickel deposit on catalyst was much higher than that of the pure nickel oxide, which can be attributed to the formation of Ni/Al-spinel in catalyst. The oxidation number of vanadium deposit on catalyst decreased after the catalyst was treated by selective activation, and decreased with the increase of the selective activation temperature. The thermodynamic equilibrium was approached when the oxidation number of vanadium was closed to 2. The deposited vanadium with lower oxidation number can be regarded as active site for desulfurization, so the sulfur content in FCC gasoline decreases. When the oxidation number of deposited vanadium is below 3, the desulfurization effect will be facilitated much more.
出处
《石油学报（石油加工）》
EI
CAS
CSCD
北大核心
2005年第5期28-35,共8页
Acta Petrolei Sinica(Petroleum Processing Section)
关键词
沉积金属
氧化数
钒
择效活化
程序升温还原
催化裂化
汽油硫含量
metal deposits
oxidation number
vanadium
selective activation
temperatureprogrammed reduction（TPR）
FCC
sulfur content in gasoline
