柠檬酸改性金属磷化物对4,6-二甲基二苯并噻吩加氢脱硫性能

Study of Hydrodesulfurization of 4,6-Dimethyldibenzothiophene over Metal Phosphide Catalysts Modified by Citric Acid

研究了柠檬酸(CA)对磷化物催化剂(Ni 2 P,MoP和WP)的加氢脱硫性能的影响,并通过N 2吸附、XRD、TEM和H 2-TPR等表征手段分析CA对载体的质构性质、磷化物活性相形貌以及金属-载体之间的相互作用的影响。在4,6-二甲基二苯并噻吩(4,6-DMDBT)的催化反应中,引入CA提高了Ni 2 P和MoP催化剂的本征活性。如Ni 2 P/SiO 2-CA和MoP/SiO 2-CA,其催化转换频率分别为6.2×10^-4 s^-1和1.8×10^-4 s^-1,优于Ni 2 P/SiO 2(5.8×10^-4 s^-1)和MoP/SiO 2(1.4×10^-4 s^-1),而引入CA降低了WP催化剂的加氢脱硫活性。结果表明,引入CA增强了金属Ni或Mo与SiO 2载体之间的相互作用,提高磷化物活性相的分散度,暴露更多的活性位点,导致催化活性增加,而对于WP催化剂却未观察到此现象。此外,Ni 2 P/SiO 2-CA也具有较高的表观催化性能,对4,6-DMDBT的转化率为87.2%,高于Ni 2 P/SiO 2催化剂(77.8%)。

The influence of the citric acid(CA)on the hydrodesulfurization(HDS)performance of the metal phosphide catalyst was studied.A series of characterization methods including N 2 adsorption,XRD,TEM,and H 2-TPR were used to analyze the effect of CA on the textural properties,the morphology of metal phosphide active phase,and metal-support interaction.An activity test for the HDS of the 4,6-dimethyldibenzothiophene(4,6-DMDBT)demonstrated that the catalytic activity of the Ni 2 P and MoP catalysts were improved by the addition of CA.The obtained turnover frequencies for Ni 2 P/SiO 2-CA and MoP/SiO 2-CA were 6.2×10^-4 s^-1 and 1.8×10^-4 s^-1,respectively,higher than that Ni 2 P/SiO 2(5.8×10^-4 s^-1)and MoP/SiO 2(1.4×10^-4 s^-1)catalysts without CA.By contrast,no enhancement was obtained for the supported WP catalyst.The characterization results suggested that the addition of CA into the Ni or Mo species impregnation solution could strengthen the metal-support interaction,resulting in the metal phosphide active phase with good dispersion,which was not observed for the WP catalyst.Then,the more exposure of the active sites for metal phosphide catalyst could enhance the catalytic performance.Also,the apparent catalytic activity for Ni 2 P/SiO 2-CA in the HDS of the 4,6-DMDBT was 87.2%,much higher than that of Ni 2 P/SiO 2 catalyst(77.8%).