Ni/Al_2O_3石蜡加氢精制催化剂的研制与表征

Preparation and Characterization of Ni/Al_2O_3 Wax Hydrofining Catalyst

采用化学分析正电子湮没谱(PA SCA),氨吸附-程序升温脱附(NH3-TPD),电子能谱(XPS),X光衍射(XRD)和低温氮物理吸附(BET)等技术,研究了A l2O3载体及N i/A l2O3石蜡加氢精制催化剂的制备过程和条件。研究表明:在制备A l2O3过程中加入淀粉及H3PO4,可以在相对低的焙烧温度下制备出大孔径的A l2O3,该A l2O3表面只含有弱酸中心和少量中等强度酸中心。再以含镍化合物溶液浸渍该A l2O3载体,制备出N i/A l2O3催化剂。实验考察了焙烧温度对镍在催化剂表面上分散的影响,发现在450°C的焙烧条件下,N i/A l2O3催化剂表面上形成了非晶态或无定型态金属镍。小型反应活性评价结果表明,该催化剂具有优良的石蜡加氢精制性能,还兼有脱除石蜡原料中含金属化合物的能力。

PASCA （Positron annihilation spectroscopy for chemical analysis）, in conjunction with NH3-TPD（NH3-temperature programmed desorption）, XPS（X-ray photoelectron spectroscopy）, XRD（Xray diffraction）, and N2 physics-sorption （BET）, was used to study the preparation of Al2O3 and Ni/Al2O3 wax hydrofining catalysts. The test results show that, with the introduction of starch and H3PO4 as additives into the Al2O3 carrier during preparation, the Al2O3 carrier with larger pore size can be obtained at relative low calcination temperature. There mainly are weak acid sites on the carrier surface, and a small amount of medium acid sites for the rest. Thus, the Ni/Al2O3 was prepared with such carrier by impregna tion of Ni-contained solution. Studies of calcination temperatures on nickel dispersion reveal that, metal nickel, using above-prepared Al2O3 as support and calcined at 450℃, forms amorphous structures （clusters） on surface of the catalyst. The pilot plant test results also show that the Ni/Al2O3 catalyst has high activity for wax hydrofining, as well as demetallation ability.