Influence of Pluronic® P123 Addition in the Synthesis of Bulk Ni Promoted MoS2 Catalyst. Application to the Selective Hydrodesulfurization of Sulfur Model Molecules Representative of FCC Gasoline

Abstract

A way to improve hydrotreatment processes is to enhance the intrinsic activity of Ni or Co promoted MoS2 catalysts that are commonly used in such reactions. The aim of this work was to investigate the impact of the presence of Pluronic® P123 as a structuring agent during the synthesis of Ni promoted MoS2 catalysts (named NiMoS) in water at room temperature. A series of analyses, i.e., X-ray diffraction (XRD), chemical analysis, inductively coupled plasma mass spectrometry (ICP-MS), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), helped in characterizing the NiMoS-P123 and NiMoS catalysts, the latter being prepared in the absence of polymer. Both compounds contained MoS2 phase (~85 atomic% considering Mo atoms), a similar amount of mixed Ni-Mo-S phase (40–50% considering Ni) and some amount of NiS and Ni-oxidized impurity phases. The main differences between the two catalysts were a much larger specific surface area (126 m2·g−1 instead of 31 m²·g−1) and a better dispersion of the active phase as shown by the lower slab stacking (2.7 instead of 4.8) for NiMoS-P123, and the presence of C in NiMoS-P123 (9.4 wt.% instead of 0.6 wt.%), indicating an incomplete decomposition of the polymer during thermal treatment. Thanks to its larger specific surface area and lower slab stacking and therefore modification of active Mo site properties, the compound prepared in the presence of Pluronic® P123 exhibits a strong increase of the catalytic activity expressed per Mo atom for the transformation of 3-methylthiophene. Such improvement in catalytic activity was not observed for the transformation of benzothiophene likely due to poisonous residual carbon which results from the presence of Pluronic® P123 during the synthesis.

Three-dimensionally ordered macro–mesoporous CoMo bulk catalysts with superior performance in hydrodesulfurization of thiophene

“…Moreover, the CoMo-PF-1 catalyst exhibits the relatively low stacks of MoS 2 for the maximum HDS activity due to the appropriate amount of F127 addition, which is in accordance with the results of the preparation of HDS catalysts with the addition of surfactants. 12,13,38 And the failure in the formation of the 3DOM structure is responsible for the lowest thiophene conversion over the CoMo-PF-3 catalyst. Aer changing the reaction pressure from 0.1 to 1 MPa at 360 C, the thiophene conversion over each bulk catalyst is signicantly improved due to the enhancement of the contact between the H 2 /thiophene and the active sites under the high pressure (Fig.…”

“…23 Generally, the HDS catalysts with the low stacking number of slabs and short slab length demonstrate the high dispersion of MoS 2 , resulting in the high HDS activity as reported in previous literatures. 12,13,38,39 The HRTEM characterization results and the related calculation of MoS 2 dispersion were added in Fig. S2 and Table S1.…”

“…32 In addition, the introduction of surfactants can also improve the dispersion of the active phase of the prepared catalysts, and further enhance the HDS performance. 12,13,33 Therefore, these results enlighten us to employ the surfactants to create the mesoporous pores in the walls of 3DOM bulk catalysts for improving their HDS activity.…”

“…6 It is also possible to directly investigate the morphology and stacks of Mo(W)S 2 for further improving the HDS activity without the inuence of support. 7,12,13 However, the absence of support would result in the poor dispersion of the active metals. Therefore, bulk catalysts usually exhibit much lower atom efficiency than some supported catalysts, which limits their application and development.…”

“…To address the above issues, some researchers tried to increase the surface area of bulk catalysts by adding a wide variety of additives such as ethylene glycol, polyvinylpyrrolidone (PVP), and pluronic 123 (P123). 7, [12][13][14][15] However, the utilization of active metals is still unsatisfactory. Therefore, it is still a challenging subject to search the highly efficient methods for the full utilization of active metals in bulk catalysts.…”