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
, Denis Uzio 3, Sylvette Brunet 2,*, Patrick Lacroix-Desmazes 1 and Annie Pradel 1Round 1
Reviewer 1 Report
The article is about the synthesis, and the effect of the use of Pluronic, of catalysts based on MoS2, and their catalytic behavior in the hydrodesulfurization of model molecules of FCC gasoline. The topic is interesting and the results presented are publishable. However, the current version of the manuscript requires the correction of some points (listed below) to be considered for publication in Catalysts.
Title: the article title is poorly expressed and it must be clarified.
Abstract:
The expression “Ni(Co)-promoted” in line 17 is unclear. Please check. “NiMoS”, in line 19, is not a valid molecular formula. Use scripts (Ni-Mo-S) to avoid confusion in the reader is recommended. Exceptionally, NiMoS could be used as the author suggests if the term has been previously described. The composition and properties of the catalysts are described confusingly (lines 22-27). For example: “Both compounds contained MoS2 phase (~85 atomic%), a similar amount of mixed Ni-Mo-S phase (40-50%) and some amount of NiS and NiOx phases” seems to be wrong since their sum is above 100%... It should be clarified (because the percentages are relatives) and focus on the most relevant for the catalytic performance that is summarized below. In addition, the catalytic results should be rewritten in a more concise and clear manner (lines 27-32). The most relevant results of the work should be highlighted here.
Introduction: In addition to alumina, the reviewer misses other widely used supports such as zeolites or graphitic carbons, which are not even mentioned in the introduction. There are Ni-MoS2 articles on these supports that should be cited here.
https://doi.org/10.1016/j.apcatb.2013.11.019
https://doi.org/10.1016/j.cattod.2009.07.093
Results.
The sections selected are fine identified but the titles are very vague: 1. Catalysts properties 2.2. Catalytic perfomances… (performances is wrongly written also). Line 98: the “sulfide Ni-Mo-S phase” does not exist. Please check. Line 133: the phrase “no microporosity is evidenced in either of the two catalysts” is not exact. Figure 1 clearly shows that both materials have microporosity (b more than a). they could be easily calculated: the micropore surface area is obtained by subtraction of the external surface area (obtained by t-plot method) to the SBET. It would be possible to calculate the average number of layers of MoS2 by XRD (Table 3)? Mo 3d and Ni 2p XPS regions for NiMoS-P123 are missing. Why these types of nanoparticles have not been supported? One wonders if that would improve its catalytic performance and if it would avoid the use of ultracentrifuge in their preparation. Following the discussion in lines 172-176, It could be anticipated that the size of the MoS2 crystals (using Pluronic) are below the resolution of the XRD. Their sizes are very small (2 or 3 layers) as seen by TEM in Figure 8. I would change the term “stacking” by number of layers in Figure 10. Fitting of the data in Figure 11 is not correct. The error is not shown either.
Format: all the figures are enormous. I would recommend reducing their size along the manuscript.
Units: the use of “.” must be changed by “·” in the units. For example: “126 m2. g-1” in line 26 would be “126 m2· g-1”
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The following manuscript reports an innovative method of synthesis of NiMoS-based hydrodesulphurization catalysts using PLURONIC surfactant. The investigated materials were characterized by different techniques (XRD, XPS, BET, TEM) to identify the phases present and their morphology.
However, some points remain to be clarified and the true advantage of the proposed synthesis should be emphasized. In particular, the catalytic activity seems, as evidenced by the authors, only marginally improved for the transformation of 3MT, but significantly suppressed for the transformation of BT. Therefore, the doubt remains on the utility of having catalysts prepared with this modality, even if they have a high surface area. Furthermore, a sulfidation step was used anyway.
In figures XPS 6 and 7 the components of Ni2p3 / 2 and their satellites, because there are 3 deconvolution peaks for each phase (NiS, NiO and NiMoS) to what do they correspond?
The characterization of the carbon residues resulting from the partial decomposition of PLURONIC was not made, but these residues are responsible for the low activity. Has C1s been analyzed, or is environmental contamination too high to say something? Have TEM images shown anything attributable to these residues?
No methods have been proposed to remove carbon residues, for example by raising the sample pretreatment temperature or by varying the ratio of PLURONIC in the synthesis. What happens to the catalytic activity at higher temperature > 523K? Can there be an "activation" of the NiMoS-P123 catalyst?
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript entitled “Influence of Pluronic® P123 addition in the synthesis of bulk NiMoS catalyst on catalytic performances in hydrodesulfurization of sulfur model molecules representative of FCC gasoline” deals on the study of the effect of the presence of template agent (Pluronic) in the catalytic performance of NiMo Catalysts in the HDS of 3-methylthiophene and benzothiophene. The research is original and into the scope of Catalysts. The paper contains interesting information, but major changes are mandatory to be considered as publishable. Some suggestions and question are indicated as follows:
1.- Abstracts: The first sentence presents general information and can be removed.
2.- Introduction: Please, write “Group 6” instead of “Group VIB”, and “Groups 9 and 10” instead “Group VIIB”.
3.- Results: Please indicate how was evidenced this sentence “As expected, only traces of C or H residue are visible in the absence of polymer”.
4.- Please, explain why the thermal treatment was carried out at 320 ºC. This is a relative low temperature.
5.- The formation of a composite MoS2-C was not evidenced. This sentence “Furthermore, the remaining of a carbonaceous phase due to an incomplete removal of the polymer during the washing and the thermal treatment steps may contribute to the formation of a mesoporous composite MoS2-C phase” requires to be supported.
6.- Line 160: Please, XRD diffractograms are not spectra. Be careful with this basic mistake. The caption of Figure 3 must be also mended.
7.- The deconvolution of the Ni 2p core level spectra of Figures 6 and 7 are not admissible. The assignations are wrong. Please, consider that in the case of NiO, the Ni 2p3/2 main peak appears at about 854 eV. This part needs to be rewritten.
8.- Concerning the catalytic study, there are many questions and doubts: i) why was selected 250ºC as reaction temperature? This is a relatively low reaction temperature. ii) The same question about the pressure. iii) What is the stability of the studied catalysts?
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The authors have successfully corrected the manuscript according to the reviewer's suggestions. The article can be published in Catalysts.Author Response
Thank you.
Reviewer 2 Report
The manuscript has been revised in the parts I requested. However, the catalytic performances are similar or worse when using pluronic in the synthesis. Why do we have to use it? What is the advantage? Furthermore, the sulfidation step is always present.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The revised manuscript has been improved, but the decovolutions of the Ni 2p core levels spectra in Figures 6 and 7 are not right. Ii is not possible to observe a chemical shift of about 2 eV between the contribution assigned to NiS and NiMoS. But also the high binding energy value assigned for NiO is not right, in spite of the references indicayed by the authors. This part needs to be rewritten.
Author Response
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Author Response File: Author Response.pdf
