Effect of Mono-, Di-, and Triethylene Glycol on the Activity of Phosphate-Doped NiMo/Al2O3 Hydrotreating Catalysts

Abstract

The effect of glycols on the catalytic properties of phosphate-doped NiMo/Al2O3 catalysts in the hydrotreating of straight-run gas oil (SRGO) was studied. The NiMo(P)/Al2O3 catalysts were prepared using ethylene glycol (EG), diethylene glycol (DEG), and triethylene glycol (TEG) as additives. The organic agent was introduced into the aqueous impregnation solution obtained by the dissolving of MoO3 in H3PO4 solution, followed by Ni(OH)2 addition. The Raman and UV–Vis studies show that the impregnation solution contains diphosphopentamolybdate HxP2Mo5O23(6−x)− and Ni(H2O)62+, and that these ions are not affected by the presence of glycols. When the impregnation solution comes in contact with the γ-Al2O3 surface, HxP2Mo5O23(6−x)− is decomposed completely. The catalysts were characterized by Raman spectroscopy, low-temperature N2 adsorption, X-ray photoelectron spectroscopy, and transmission electron microscopy. It is shown that the sulfide catalysts prepared with glycols display higher activity in the hydrotreating of straight-run gas oil than the NiMoP/Al2O3 catalyst prepared without the additive. The hydrodesulfurization and hydrodenitrogenation activities depend on the glycol type and are decreased in the following order: NiMoP-DEG/Al2O3 > NiMoP-EG/Al2O3 > NiMoP-TEG/Al2O3 > NiMoP/Al2O3. The higher activity of NiMoP-DEG/Al2O3 can be explained with the higher dispersion of molybdenum on the surface of the catalyst in the sulfide state.

A Paper-Based Device for Ultrasensitive, Colorimetric Phosphate Detection in Seawater

“…The fact that ethylene glycol stabilizes molybdenum complexes has been previously reported in the literature [ 30 ], and is likely due to chelation between the small molecule diol and molybdenum that retards undesired side reactivity. Of note, other aliphatic alcohols, including glycerol and 3-propane diol, were less effective at stabilizing the molybdenum reagent, as were supramolecular additives with multiple hydroxyl moieties, including α, β, and γ-cyclodextrin.…”

Effect of Organic Additives on the Structure and Hydrotreating Activity of a CoMoS/Multiwalled Carbon Nanotube Catalyst

“…It is well known that DEG does not form complex compounds with Co or Mo in solution. 24 However, a positive effect of the glycols on the activity of CoMoP catalysts based on γ-alumina was established. 64 It is assumed that the positive effect of glycols may be due to the fact that they interact with coordinatively unsaturated Al 3+ sites on the surface of alumina.…”

“…41 The use of DEG as an organic additive does not lead to the formation of Co or Mo complex compounds in the solution. 24 The evaluation of the morphology and textural characteristics of the obtained CoMoS catalysts showed that the use of various organic additives had an insignificant effect. The sulfide particles with a slab length of 2.0−3.0 nm are predominant in the CoMoS samples prepared with CA and NTA, whereas the CoMoS sample prepared using DEG has a slightly higher slab length (2.0−3.3 nm).…”

“…16,21,22 The addition in the impregnation solutions of noncomplexing organic additives, for instance, diethylene glycol (DEG) and triethylene glycol (TEG), is also the effective way to improve HDS catalyst performance. 23,24 The addition of glycols facilitates the formation of HPA complexes in solution, which form the active phase more selectively at the sulfidation stage. 23 It was also shown for CoMo/Al 2 O 3 catalysts that TEG interacts with OH groups and coordinatively unsaturated Al 3+ sites of the alumina support.…”

“…For alumina-based hydrotreating catalysts, the addition of chelating ligands at the stage of impregnation solution preparation leads to an increase in the dispersion of active metals, an increase in the portion of the active phase in the catalyst, and, accordingly, an increase in the catalytic activity in HDS reactions. ,, The addition in the impregnation solutions of noncomplexing organic additives, for instance, diethylene glycol (DEG) and triethylene glycol (TEG), is also the effective way to improve HDS catalyst performance. , The addition of glycols facilitates the formation of HPA complexes in solution, which form the active phase more selectively at the sulfidation stage . It was also shown for CoMo/Al 2 O 3 catalysts that TEG interacts with OH groups and coordinatively unsaturated Al 3+ sites of the alumina support .…”