Effect of Phosphorus Modification on the Acidity, Nanostructure of the Active Phase, and Catalytic Performance of Residue Hydrodenitrogenation Catalysts

Abstract

A series of NiMoP( x )-Al catalysts with different phosphorus contents were prepared by the incipient wetness co-impregnation method. The effects of phosphorus modification on the acidity, active phase nanostructure, and catalytic properties of the residue hydrodenitrogenation catalysts were investigated to find the role of phosphorus in the catalytic mechanism. The results of temperature-programmed desorption of NH 3 and pyridine IR spectroscopy of the catalysts indicate that phosphorus modification can increase the total acid and Brønsted acid. Transmission electron microscopy analysis shows that phosphorus modification increases the stacking number N A , reduces the slab length L A of the active MoS 2 phase, and increases the Mo dispersion f Mo , leading to the promotion of the sulfidation degree of the active Mo phase and thus increasing the denitrification rate. The catalyst with a 3.4 wt % P 2 O 5 loading shows the highest Brønsted/Lewis acid ratio, the largest amount of three-layer active phases, the smallest L A , the highest f Mo , the optimal sulfurization degree, and the highest denitrification rate, 63.6%, indicating the correlation between the nanostructure of the active phase and its catalytic property because of the addition of phosphorus.

Development of a New Ternary Al2O3–HAP–Pd Catalyst for Diethyl Ether and Ethylene Production Using the Preferential Dehydration of Ethanol

“…and acid density (μmol m –2 ) for all different catalysts. There are mainly three desorption ranges in the TPD profiles: the desorption peak at a lower temperature below 300 °C is attributed to weak acid sites; the second one at a medium temperature between 300 and 450 °C is assigned to moderate acid sites; and the third one at a high temperature above 450 °C is ascribed to strong acid sites. , The sum of all the three acid sites measured by the total ammonia desorbed gives the total acidity of the catalysts. The bare Al 2 O 3 catalyst displays the largest total surface acidity maybe due to the high surface area as well as the high physical adsorption of NH 3 in the framework of the Al 2 O 3 catalyst .…”