Ni2P/TiO2的制备及其对苯加氢反应的催化性能

Ni2P/TiO2的制备及其对苯加氢反应的催化性能

  • 摘要: 采用程序升温还原方法制备了TiO2负载的晶态Ni2P催化剂。用X射线衍射(XRD)及低温N2吸附(BET)等技术对样品的物相、比表面积等性质进行了表征。以苯气相加氢为模型反应考察了Ni2P/TiO2催化剂加氢性能,并对Ni2P负载量、前驱体中P的质量分数对催化剂的物相及性能的影响进行了研究。实验结果表明, TiO2负载的晶态磷化镍催化剂上,Ni2P是主要物相。Ni2P/TiO2催化剂对苯加氢反应具有较高的活性、选择性以及良好的稳定性能。Ni2P/TiO2制备对催化剂的性能有影响。Ni2P负载量增加,催化剂的活性先升高后降低,Ni2P负载量为12%时催化剂活性较高。催化剂前驱体中P的质量分数越高,制备出的催化剂对苯加氢反应的稳定性越好,但随前驱体中P的质量分数增加,催化反应的活性先升高,后降低。与Ni2P/SiO2比较,Ni2P/TiO2催化剂具有较高的活性和稳定性。

     

    Abstract: Transition metal phosphides have recently been reported as a new class of highactivity hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) catalysts. Among them, Ni2P has better HDS and HDN activity. The surface area of unsupported Ni2P catalysts is rather low (< 1m2/g). To increase the active surface area, the dispersion of Ni2P on a highsurface support is needed. SiO2 is widely used as support of the Ni2P catalysts. TiO2 is commonly used as support of catalysts. It can cause strong interaction with metal, that facilitates disperse of active components on its surface. In this paper, a series of supported Ni2P catalysts on TiO2 were prepared via temperatureprogrammed reduction. The structure characteristics of samples have been characterized by means of Xray powder diffraction(XRD),N2 adsorption (BET) and temperatureprogrammed reduction (H2TPR). Benzene hydrogenation was chosen as a model reaction to investigate the influences of Ni loading, initial Ni/P mole ratio. Results showed that Ni2P was the main phase on the TiO2 supported catalysts. Ni2P/TiO2 catalysts had high activity with 100% cyclohexane selectivity and excellent stability in benzene hydrogenation reaction. The preparation factors had great effects on the activity of benzene hydrogenation reaction. With the increase of Ni2P loading,the activity of the Ni2P/TiO2 catalyst increased firstly and then decreased. Benzene conversion reached a maximum with Ni2P loading of about 12%. The activity and stability of the Ni2P/TiO2 catalysts were also affected profoundly by the initial phosphorus content. With the increase of the initial P/Ni mole ratio,the reaction stability is better,but the steady activity increased firstly and then decreased. In comparison with Ni2P/SiO2, Ni2P/TiO2 catalysts had much better activity and stability in benzene hydrogenation reaction.

     

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