含双金属的超稳Y沸石负载SO_4^(2-)/ZrO_2强酸性催化剂上正庚烷临氢异构化

Hydroisomerization of n-heptane over bimetal-bearing SO_4^(2-)/ZrO_2 catalysts supported on USY zeolite

用超稳Y沸石(USY)负载SO42-/ZrO2固体超强酸,并以此为载体制备含Pt双金属催化剂,用XRD和H2-TPR表征了催化剂的物化性质,并在常压固定床反应器上考察催化剂的正庚烷临氢异构化反应性能。结果表明,USY负载了SO42-/ZrO2和双金属以后仍能保持沸石原有结构;贵金属Pt、金属助剂以及ZrO2等在USY载体上能够高度分散。在含Pt的催化剂中掺杂了Cr或Al金属助剂以后,正庚烷异构化产物选择性有了明显的提高,且具有更好的稳定性和低温活性;在USY负载SO42-/ZrO2和0.4%Pt的催化剂上,正庚烷的转化率为42.1%时,异构化产物的选择性只有69.6%,而在掺杂了与Pt摩尔比为5∶1的Cr或Al后,正庚烷的转化率分别为44.3%和42.1%时,异构化产物的选择性分别可提高到88.9%和89.5%。

The bimetal-bearing SO4^2- /ZrO2 superacid catalysts supported on ultra stable Y （USY） zeolite were prepared by impregnation and characterized with XRD and H2-TPR. Their catalytic activities were evaluated in the hydroisomerization of n-heptane with an atmospheric fixed-bed reactor. The USY support well kept its pore structure in catalysts and the metal species were highly dispersed on the support. The Ptbearing catalysts doped with Cr or Al were catalytically much more stable and exhibited higher catalytic activity and selectivity than the catalysts without dopants. Over the catalyst with a Pt loading of 0.4% （mass） and ZrO2 loading of 10% （mass）, the conversion of n-heptane was 42.1% with a selectivity of only 69.6% for isomerization products, while over the catalysts doped with Cr or Al with a molar ratio of Cr （A1） to Pt 5 ： 1, the conversion of n-heptane was 44.3% and 42.1% with the selectivity for isomerization products as high as 88. 9 % and 89.5 % respectively.