Ce促进Ni/SAPO-11催化剂上正庚烷的临氢异构化

Ni/SAPO-11 Promoted by Rare Earth Element Ce for Hydroisomerization of n-Heptane

通过浸渍法制备了Ni/SAPO-11催化剂,并进一步通过分步浸渍法制备了Ni-Ce/SAPO-11双金属催化剂,对其晶相结构和表面酸性进行了表征.实验结果表明,Ce的引入导致比表面积和孔容增大,总酸量升高而酸强度降低,金属Ni在载体SAPO-11表面的分散度提高.通过对正庚烷的临氢异构化反应研究发现,引入Ce可以显著提高异庚烷的选择性.在n(H2)/n(n-C7H16)=12,MHSV=3.52 h-1,催化剂量0.3 g,反应温度300℃条件下,Ni-2%Ce/SAPO-11催化剂的正庚烷转化率可达25.4%,异庚烷的选择性可达90.4%.

The monometallic catalyst Ni/ SAPO-11 was prepared via the impregnation method. Then, the bi-metallic catalyst Ni-Ce / SAPO-11 was prepared via the sequential impregnation method. The crystal structure and acidity of these two catalysts were determined by X-ray powder diffraction, Brunauer-Emmett-Teller （BET） methods and temperature-programmed desorption of ammonia. With addition of Ce, the BET surface areas and porous volume of Ni/ SAPO-11 and total acidity were increased, and the acid strength was de-creased. Introduction of Ce improved the dispersion of Ni on the surface of SAPO-11. Addition of Ce could improve the selectivity of the hydroisomerization of n-heptane considerably. Under the conditions of n（H2 ） /n（n-C7 H16 ）= 12, weight hourly space velocity =3. 52 h-1 , catalyst weight=0. 3 g, and the reaction tempera-ture of 300 ℃, the conversion of n-heptane could reach 25. 4% and the isomerization selectivity to i-heptane could reach 90. 4% .