高温煤焦油中菲含量高,将菲深度加氢饱和得到全氢菲,可提升菲利用率,且全氢菲密度大,热值高,可作为喷气燃料理想组分。然而,在菲加氢反应过程中菲与中间加氢产物的竞争吸附不利于菲在催化剂上吸附活化,且对称八氢菲进一步加氢是菲加氢饱和过程的速控步骤,其吸附活化困难不易解决,催化剂活性难以满足加氢需求。根据稠环芳烃与过渡金属间π络合吸附机理,在反应物吸附活化过程中,稠环芳烃分子和活性金属分别充当电子供体和电子受体,故Ni基催化剂中活性金属Ni处于缺电子状态时利于生成全氢菲,但关于Ni缺电子量及其电子结构如何影响催化剂菲、对称八氢菲加氢性能的原因需进一步探究。此外,基于负载型Ni2P催化剂稳定性高、耐硫、耐氮性强等优势,采用次磷酸盐歧化法通过调变P/Ni物质的量比制备具有不同Nid电荷密度的Ni2P/Al2O3催化剂,考察Nid电荷密度对菲、对称八氢菲吸附和反应性能的影响规律。结果表明,在320℃、5MPa、空速1309h-1反应条件下,Ni-2.5P/Al2O3催化剂转换频率fTO最高(44.64´10-3s-1)。通过吸附活化熵描述菲、对称八氢菲与催化剂表面间相互作用强度,发现菲、对称八氢菲在不同Ni-xP/Al2O3催化剂表面吸附强度不同。通过定量计算Nid电荷密度,明确了Ni2P/Al2O3催化剂用于菲加氢反应时适宜Nid电荷密度约-0.24e,对称八氢菲加氢反应适宜的Nid电荷密度约-0.05e。

The content of phenanthrene in high temperature coal tar is relatively high. The hydrogenation saturation of phenanthrenethrough catalytic not only expands the utilization of phenanthrene, but also obtains perhydrophenanthrene, which is an ideal component forjet fuel due to its high density and calorific value. However, the competitive adsorption between phenanthrene and intermediate hydrogenation products in the process of phenanthrene hydrogenation is not conducive to the adsorption and activation of phenanthrene on the catalyst, and the further hydrogenation of symmetric octahydrophenanthrene is the speed control step in the hydrogenation saturation process ofphenanthrene. Due to the difficulty in adsorption and activation of symmetric octahydrophenanthrene on the catalyst, the catalyst activity isoften difficult to meet the hydrogenation demand. According to the π-complex adsorption mechanism between polycyclic aromatic hydrocarbon and transition metals, polycyclic aromatic hydrocarbon and active metals act as electron donors and electron accepters respectivelyin the process of reactant adsorption and activation. Therefore, when the active metal Ni in the Ni-based catalyst is in the electron-deficient state, it is conducive to the formation of perhydrophenanthrene. However, the reason why the amount of Ni electron deficiency and itselectronic structure affect the performance of the catalyst for hydrogenation of phenanthrene and symmetric octahydrophenanthrene needs tobe further explored. In addition, considering the advantages of the supported Ni2P catalysts, such as high stability, strong sulfur resistanceand nitrogen resistance, Ni2P / Al2O3 catalysts with different d charge densities were prepared by adjusting the P / Ni amount-of-substanceratios using hypophosphite disproportionation method, to investigate the influence of Ni d charge density on the adsorption and reactionperformance of phenanthrene and symmetric octahydrophenanthrene. The results show that under reaction conditions of 320 ℃ , 5 MPa,and Weight Hourly Space Velocity (WHSV) of 1 309 h-1, the Ni-2.5P / Al2O3 catalyst obtains the highest turnover-frequency(fTO) of44.64×10-3 s-1. By describing the interaction strength between phenanthrene, symmetric octahydrophene, and catalyst surfaces throughadsorption activation entropy, it was found that the adsorption strength of phenanthrene and symmetric octahydrophenanthrene on the surface of Ni-xP / Al2O3 catalysts with different P / Ni molar ratios are different. Further, by quantitatively calculating the Ni d charge density,it was identified that the suitable Ni d charge density for the hydrogenation of phenanthrene over Ni-xP / Al2O3 catalyst is about -0.24 e,and the suitable Ni d charge density for the hydrogenation of symmetric octahydrophenanthrene is about -0.05 e.

0 引言

1 试验

   1.1 Ni-xP/Al2O3催化剂的制备

   1.2 Ni-xP/Al2O3催化剂的表征

   1.3 催化剂活性评价

   1.4 反应动力学参数测定

   1.5 Ni d电荷密度计算方法

2 结果与讨论

   2.1 Ni-xP/Al2O3催化剂结构表征

   2.2 Ni-xP/Al2O3催化剂活性评价

3 结论