Oxidative Desulfurization of Tire Pyrolysis Oil over Molybdenum Heteropolyacid Loaded Mesoporous Catalysts

Round 1

Reviewer 1 Report

Kur and co-workers present an interesting work based on ODS with Mo-containing mesoporous catalyst. I recommend it publication after having improved the following mistakes:

Some general comments:

Lines 43-44: Some references about the use of TPO in cement, thermal power etc should be provided.

Line 93: Typing error: there is a “f” in the middle of the sentence: “ as f discussed”

Line 209: NH3 desorption profiles must be shown if their results are mentioned in the text. Otherwise, that information should be eliminated from the manuscript. Every experimental information must be justified by the experimental evidences. It is not accepted to say “Figure is not shown”

Line 219: Figure 4 must be cited in the text, and its title must be below the figure, as in the others.

Line 226: the terms “chemical states” is not correct. Replace it by “coordination environment and oxidation states”

Figures 7, 8 and 10 are too big for the format of the paper. Figures 7 and 8 only consist of 3 and 4 columns. In general figures need to be resized.

Questions

1. What is the role of HPMo in ODS? A control test with Ti-Al2O3 and Ti-TUD-1, without HPMo, needs to be done in order to determine if HPMo affects.
2. Regarding the outcome of TBHP (line 271), have the authors thought of a possible explanation for this? It is quite uncommon that TBHP is less oxidant than H2O2. In fact, as far as solubility is concerned, TBHP is more soluble that H2O2. TBHP is such a strong oxidant that it decomposes with time, is it possible that the TBHP employed was in bad condition?
3. Serious concept mistake was found here. Leaching can never be confirmed by XRD, as mentioned in line 385, the disappearance of the typical Kiggins reflections might also be due to its transformation in a different crystalline phase. XRD can only tell you whether your material has changed its structure or not. Thus, it is required to perform ICP analysis of the reaction liquors to confirm the presence and quantity of Mo. Or the opposite, an analysis of the recovered material to quantify the loss of Mo. Without this information you can only hypothesize that Mo ions might have been replaced. Besides, the conversion of each run must be shown in a column figure (similar to Figure 7 and 8). If after ICP analysis Kiggins ions is leached, some recovery treatments could be performed to reobtain the starting catalyst.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The authors have used Ti-supported alumina for the oxidation of DBT. This reaction is important in the industry for the desulfurization aims. The catalyst seems a good candidate for this aim as well. I can be published in the journal, however, there are some major points that the authors should address and consider in the paper:

TiO2 phase is unknown, it should be determined by XRD whether it is anatase, rutile, or amorphous. Furthermore, TiO₂ has strong stability, catalytic and photocatalytic activity and it can be found in many forms. These should be mentioned in the introduction: for this, authors can use the following reference: 

Applied Catalysis B: Environmental, 2021, 297, 120380; Journal of Membrane Science, 489, 43-54; Applied Catalysis B: Environmental, 2021, 297, 120380; Desalination, 292, 19-29. DOI: 10.1016/j.desal.2012.02.006

The recent advances and similar works in the oxidation of DBT should be mentioned in the introduction: For example, recently, Assadi et al., have synthesized a catalyst for oxidation of DBT. they have merged periodic mesoporous organosilica and mesoporous aluminosilica for green oxidation of DBT. See Molecular Catalysis journal volume 482.

The FTIR figures are poorly prepared, please revise the title and grids. 

Please provide any SEM or TEM image to show the morphology and the structure of the catalyst.

The comparison of the previous works with the current work should be in a table. 

English should be revised. 

 

 

Author Response

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Reviewer 3 Report

The authors have done interesting work in the field of oxidative desulfurization. The possibility of using the method of purification from sulfur-containing compounds of pyrolysis oil from tires is shown. It should be noted that this type of materials has not been studied in the literature for the possibility of oxidative purification. The work can be released for publication after substantial revision. - The introduction should be supplemented with examples of the use of catalysts based on mesoporous materials for the oxidative desulfurization process (10.1021 / acs.energyfuels.8b02583, 10.1021 / acs.energyfuels.0c02008, etc.) - According to Figure 7, HPMo / Ti-Al2O3 practically does not show activity with a blank experiment without a catalyst. The authors should explain the reasons, phosphoromolybdic acid, as is known from the literature, is a manifestation of high catalytic activity in the oxidation of organosulfur compounds. - The authors write that they use light gas oil for use, because it looks like pyrolysis oil. But at the same time, the desulfurization results in Figures 6 and 7 are very different. An explanation is needed by changing the connections. - It is known that pyrolysis products contain numerous unsaturated compounds, which can also react under oxidation conditions. Is it possible that the deterioration of the results associated with side reactions of oxidation of unsaturated compounds? The authors should prove this fact or refute it by one of two methods: by studying the amount of unsaturated compounds in the pyrolysis oil before and after oxidative desulfurization, or using model mixtures containing alkenes.  

Author Response

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Round 2

Reviewer 1 Report

Proper changes have been made. 

Author Response

We thank the reviewer for his valuable inputs and for accepting our manuscript to publish in Reactions.

Reviewer 2 Report

Tge authors have replied to my comments and applied them accordingly, therefore, it's publishable in the current format.

Author Response

We thank the reviewer for his valuable inputs and for accepting our manuscript to publish in Reactions.

Reviewer 3 Report

the authors took into account the reviewer comments and corrected the text

Author Response

We thank the reviewer for his valuable inputs and for accepting our manuscript to publish in Reactions.