酸、盐处理对Pt/SAPO-11物化及其催化性能的影响

采用不同酸和盐浸渍处理SAPO-11分子筛,然后负载Pt制成改性的Pt/SAPO-11催化剂,用XRF、XRD、N_2吸附-脱附、SEM、NH_3-TPD和Py-IR对催化剂进行表征,分析其物理化学性能。结果表明,酸和盐处理没有破坏SAPO-11的骨架结构,还提高了催化剂的孔容、孔径、比表面积等性质,催化剂的酸性、酸量也明显发生了改变。在固定床反应器中,评价了改性的Pt/SAPO-11催化小桐子油一步加氢制异构烷烃性能;结合催化剂表征数据表明,颗粒粒径、比表面积、孔径、酸性和酸量影响催化剂的活性及产物分布。对比发现,经0.5 mol/L柠檬酸处理的Pt/SAPO-11催化剂孔径大小、酸性、B酸和L酸量分布合适,因此,一步加氢催化处理小桐子油性能优异;其中,生物航油组分(C_(8-16))的收率为32.47%,异构烷烃(C8-16)选择性为53.13%。

Study on the physicochemical properties and catalytic performance of Pt/SAPO-11 catalysts treated by acid and salt

SAPO-11 molecular sieves were treated with different acids and salts and the modified Pt/SAPO-11 catalysts were prepared by loading platinum on the pre-treated SAPO-11. The catalyst samples were characterized with XRF, XRD, N₂ adsorption-desorption, SEM, NH₃-TPD and pyridine Py-IR to analyze their physicochemical properties. The results showed that the modification of acid and salt did not destroy the structure of SAPO-11, but improved the pore volume, pore size and specific surface area of the catalysts, meanwhile, the acidity and acid amount of the zeolite were also changed obviously. In a fixed-bed reactor, one-step hydrgenation of Jatropha curcas oil to iso-alkanes over modified Pt/SAPO-11 catalyst was carried out. Combined with catalyst characterization results, it was concluded that those parameters, such as particle size, specific surface area, pore diameter, acidity and acid amount, would affect the activity and product distribution of the catalysts. Among these modified catalysts, it is found that the Pt/SAPO-11 catalyst treated with 0.5 mol/L citric acid solution exhibited an excellent catalytic performance in one-step hydrogenation of Jatropha curcas oil, owing to its appropriate pore size, acidity, B acid and L acid distribution. The yield of bio-jet fuel components (C_8-16) was 32.47% and the selectivity of isoparaffins was 53.13%.