Hydrogenation of Simulated Bio-Syngas in the Presence of GdBO₃ (B = Fe, Co, Mn) Perovskite-Type Oxides

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this manuscript authors have reported GdBO₃ (B = Fe, Co, Mn) perovskite-type oxides as catalyst for the hydrogenation of CO and CO₂.  But the manuscript requires a thorough revision before it can be considered further. See the comments below:

Lines 36-40: Cite few more relevant references regarding CO₂ fixation reactions and green hydrogen production published within last 4-5  years.   

Lines 97:. In fig 1, define the term С (PDF#01-078-4003) and differentiate between С (PDF#00-041-1487) and С (PDF#01-078-4003) so that the investigation can be well understood.

In table 1, BET surface area values for different samples are provided. But where is the N2 sorption isotherms? This should be provided in the supporting document file.

Page 6, table 2 caption, I don’t find any BET data in this table, then why in the caption it is written ‘specific surface area by BET’?

Authors should provide the high resolution TEM images of their GdFeO3, GdMnO3 and GdCoO3 samples for understanding the morphology, particle size and nanostructures of these catalysts.

Authors should discuss the mechanism of this hydrogenation process over these GdBO₃ catalysts.

Concerning the nature of the work, I would like to suggest to include a separate paragraph in the conclusion section highlighting all the advantages of this current catalyst over previously reported catalytic systems.

Comments on the Quality of English Language

Thorough language editing is necessary.

Author Response

Dear reviewer,

Thank you very much for your kind work, careful review, constructive suggestions and full consideration with regard to our manuscript. We have studied the comments carefully and tried our best to revise and improve the manuscript. The explanation of what we have changed in response to the reviewers’ concerns is given point by point in the following pages. And all revisions are marked in red in the revised manuscript. We hope that the corrections and explanations can meet with approval.

1. Lines 36-40: Cite few more relevant references regarding CO₂fixation reactions and green hydrogen production published within last 4-5 years.

Thank you for your recommendation. The following references have been added:

[20] Zhang, K.; Guo, D.; Wang, X.; Qin, Ye.; Hu, Li; Zhang, Yu.; Zou, R.; Gao, S. Sustainable CO₂ management through integrated CO₂ capture and conversion. Journal of CO₂ Utilization. 2023, 72, 102493, https://doi.org/10.1016/j.jcou.2023.102493.

[21] Zhang, R.; Xie, Z.; Ge, O.; Zhu, X. Recent advancements in integrating CO₂ capture from flue gas and ambient air with thermal catalytic conversion for efficient CO₂ utilization. Journal of CO₂ Utilization. 2024, 89, 102973   https://doi.org/10.1016/j.jcou.2024.102973.

[22] Latsiou, A.I.; Charisiou, N.D.; Frontistis, Z.; Goula, M.A. From CO₂ to value added chemicals: The promise of single atom catalysts. International Journal of Hydrogen Energy. 2024, 92, 465–481. https://doi.org/10.1016/j.ijhydene.2024.10.201.

2. Lines 97:. In fig 1, define the term С (PDF#01-078-4003) and differentiate between С (PDF#00-041-1487) and С (PDF#01-078-4003) so that the investigation can be well understood.

Thank you for your comment. We have corrected the technical error. (PDF#01-078-4003) is cobalt, not carbon. We have also indexed all the peaks in the diffractograms.

3. In table 1, BET surface area values for different samples are provided. But where is the N2 sorption isotherms? This should be provided in the supporting document file.

Thank you for your comment. The N₂ adsorption/desorption isotherms are presented in the supplementary materials file.

4. Page 6, table 2 caption, I don’t find any BET data in this table, then why in the caption it is written ‘specific surface area by BET’?

Thank you for your comment. It is true that table 2 does not contain BET data. The table caption has been corrected.

5. Authors should provide the high resolution TEM images of their GdFeO₃, GdMnO₃ and GdCoO₃ samples for understanding the morphology, particle size and nanostructures of these catalysts.

Thank you for your comment. Unfortunately, we are not able to provide high resolution TEM images. Our faculty and research center does not have a TEM. And due to the Christmas holidays, we will not be able to do TEM at other research centers in the near future.

6. Authors should discuss the mechanism of this hydrogenation process over these GdBO₃ 

Thank you for your comment. A discussion on the reaction mechanism has been added to the Catalytic test. (lines 404-440).

 

7. Concerning the nature of the work, I would like to suggest to include a separate paragraph in the conclusion section highlighting all the advantages of this current catalyst over previously reported catalytic systems.

Thank you for your suggestion. We have attempted to demonstrate the benefits of catalysts in the Conclusion.

In addition, we have made modifications to the language expression of the article.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

There are some issues that need to be addressed in this paper. 14, take out it was found that. Quantify the abstract and the conclusions sections. 26, define the word it. 50-53, give all states of matter in all equations. Figure 1, index all peaks. 125 combine this 1 sentence paragraph with another. Figure 3, identify all peaks. 144, take out it is known that. 158 show. Using Mn 2p to determine mixed valent state is not good. Table 2, define the - entries. 189, take out it can be seen that. 206, define the word it. 222, combine this 1 sentence paragraph with another.  250, combine this 1 sentence paragraph with another. 263, take out it was observed that. 270, take out it is worth noting that. Figure 8, give error bars on all data points. Figure 9, give error bars on all data points. 318, Russian text. Figure 10, give error bars. 

Comments on the Quality of English Language

There are a few minor issues with English out lined above that should be addressed. 

Author Response

Dear reviewer,

Thank you very much for your kind work, careful review, constructive suggestions and full consideration with regard to our manuscript. We have studied the comments carefully and tried our best to revise and improve the manuscript. The explanation of what we have changed in response to the reviewers’ concerns is given point by point in the following pages. And all revisions are marked in red in the revised manuscript. We hope that the corrections and explanations can meet with approval.

• 14, take out it was found that.

Thank you for your recommendation. It's done.

 

• Quantify the abstract and the conclusions sections.

Thank you for your recommendation. Carbon oxide conversion values and light olefin selectivity for gadolinium ferrite and manganite were added to the abstract and conclusion.

 

• 26, define the word it.

Thank you for your question. The sentence has been rewritten:

The "greenhouse effect" is causing rising temperatures and contributing to global climate change.

 

• 50-53, give all states of matter in all equations.

Thank you for your recommendation. States of matter were added to the equations.

 

• Figure 1, index all peaks.

Thank you for your recommendation. All peaks in Figure 1 have been indexed.

 

• 125 combine this 1 sentence paragraph with another.

Thank you for your recommendation. It's done.

 

• Figure 3, identify all peaks.

Thank you for your recommendation. All peaks in Figure 3 have been identified.

 

• 144, take out it is known that.

Thank you for your recommendation. It's done.

 

• 158 show. Using Mn 2p to determine mixed valent state is not good.

Thank you for your comment. Manganese, having six stable oxidation states (0, II, III, IV, VI and VIII), three oxidation states with significant multiplet splitting (II, III, IV), one oxidation state with less defined splitting or broadening (VI), and overlapping binding energy ranges for these mutiplet splitting structures, presents a serious challenge for both qualitative and quantitative analysis. The splitting between the Mn 2p3/2 and Mn 2p1/2 levels was 11.6 eV.

We have improved the figure for Mn2p.

 

• Table 2, define the - entries.

Thank you for your recommendation. The entry of Table 2 has been corrected and added to the manuscript.

 

• 189, take out it can be seen that.
• 206, define the word it.
• 222, combine this 1 sentence paragraph with another.
• 250, combine this 1 sentence paragraph with another.
• 263, take out it was observed that.
• 270, take out it is worth noting that.

Thank you for your recommendation. It's done.

 

• Figure 8, give error bars on all data points.
• Figure 9, give error bars on all data points.
• Figure 10, give error bars. 

Thank you for your recommendation. Data error bars have been added in Figures 8-10.

 

• 318, Russian text.

We apologize for the technical error. The Russian text has been removed.

 

In addition, we have made modifications to the language expression of the article.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper by Sheshko et al. presents a thorough investigation of the hydrogenation of simulated bio-syngas over GdBO₃ (B = Fe, Co, Mn) perovskite-type oxides. The authors found that the Fe/Mn-containing samples exhibited efficient catalysis of the hydrogenation of simulated bio-syngas to light hydrocarbons. And some crucial conclusions are tentatively drawn. Although this work is decent, I still have some concerns and suggestions in the paper.

1. The authors should elucidate the necessity of GdBO₃ perovskite-type oxides applied in this study and the distinctive role of Gd in the Introduction Section although it had already been mentioned in previous study.

2. In Figure 1a, some important diffraction peaks of XRD patterns was not appointed as their differences in the position and intensity still existed.

3. SEM images in Figure 2 lacks of the scale.

4. The identification of graphite and filamentary in SEM images is suggested according to the text in Line 129-132.

5. Can the nature and morphology of the carbon between Figure 1 and Figure 2 be related?

6. The bio-syngas, as mentioned in the title, was not introduced fully in the Introduction Section. And it seems that the authors mainly involved the CO₂ hydrogenation.

7. The relation between the paragraph in Line 109-113 and the paragraph in Line 117-124 seems to be fuzzy and obscure.

8. The text in Line 125-126 can be removed to other paragraph as the context was discussing the sample morphology.

9. Table 2 was not mentioned in the text. Why?

10. Please add a reference afterwards "in the literature" in Line 104.

In addition, a large number of subscripts have not been changed; and furthermore Russian language can be found in Line 318 of text. The authors should carefully proofread before submitting the manuscript.

Therefore, I suggest that this manuscript should undergo a minor revision.

Comments on the Quality of English Language

The paper by Sheshko et al. presents a thorough investigation of the hydrogenation of simulated bio-syngas over GdBO₃ (B = Fe, Co, Mn) perovskite-type oxides. The authors found that the Fe/Mn-containing samples exhibited efficient catalysis of the hydrogenation of simulated bio-syngas to light hydrocarbons. And some crucial conclusions are tentatively drawn. Although this work is decent, I still have some concerns and suggestions in the paper.

1. The authors should elucidate the necessity of GdBO₃ perovskite-type oxides applied in this study and the distinctive role of Gd in the Introduction Section although it had already been mentioned in previous study.

2. In Figure 1a, some important diffraction peaks of XRD patterns was not appointed as their differences in the position and intensity still existed.

3. SEM images in Figure 2 lacks of the scale.

4. The identification of graphite and filamentary in SEM images is suggested according to the text in Line 129-132.

5. Can the nature and morphology of the carbon between Figure 1 and Figure 2 be related?

6. The bio-syngas, as mentioned in the title, was not introduced fully in the Introduction Section. And it seems that the authors mainly involved the CO₂ hydrogenation.

7. The relation between the paragraph in Line 109-113 and the paragraph in Line 117-124 seems to be fuzzy and obscure.

8. The text in Line 125-126 can be removed to other paragraph as the context was discussing the sample morphology.

9. Table 2 was not mentioned in the text. Why?

10. Please add a reference afterwards "in the literature" in Line 104.

In addition, a large number of subscripts have not been changed; and furthermore Russian language can be found in Line 318 of text. The authors should carefully proofread before submitting the manuscript.

Therefore, I suggest that this manuscript should undergo a minor revision.

Author Response

Dear reviewer,

Thank you very much for your kind work, careful review, constructive suggestions and full consideration with regard to our manuscript. We have studied the comments carefully and tried our best to revise and improve the manuscript. The explanation of what we have changed in response to the reviewers’ concerns is given point by point in the following pages. And all revisions are marked in red in the revised manuscript. We hope that the corrections and explanations can meet with approval.

1. The authors should elucidate the necessity of GdBO₃perovskite-type oxides applied in this study and the distinctive role of Gd in the Introduction Section although it had already been mentioned in previous study.

 

Thank you for your comment. We have added some additional information to the introduction about the benefits of complex oxides such as perovskite and the role of gadolinium in them. (Lines 92-105).

 

2. In Figure 1a, some important diffraction peaks of XRD patterns was not appointed as their differences in the position and intensity still existed.

 

Thank you for your comment. We have identified all diffraction peaks and added a description to the manuscript.

 

3. SEM images in Figure 2 lacks of the scale.

 

Thank you for your comment. It's done.

 

4. The identification of graphite and filamentary in SEM images is suggested according to the text in Line 129-132.

 

Thank you for your comment. The SEM images highlighted graphite and carbon filaments.

 

5. Can the nature and morphology of the carbon between Figure 1 and Figure 2 be related?

 

Thank you for your question. I think so. Figure 1 has graphitized carbon. It's visible in the SEM. The carbon filaments are also visible in the SEM.

 

6. The bio-syngas, as mentioned in the title, was not introduced fully in the Introduction Section. And it seems that the authors mainly involved the CO₂

 

Thank you for your comment. In response to your request, we have added more information about bio-syngas in the Introduction. Lines 37-46.

 

7. The relation between the paragraph in Line 109-113 and the paragraph in Line 117-124 seems to be fuzzy and obscure.

 

Thank you for your comment. We have revised the section on sample surface morphology.

 

8. The text in Line 125-126 can be removed to other paragraph as the context was discussing the sample morphology.

 

Thank you for the comment. The sentence has been corrected and put in front of Table 1.

 

9. Table 2 was not mentioned in the text. Why?

 

Thank you for your comment. It is a technical error. The reference to Table 2 has been added to the manuscript. Lines 222-223

 

10. Please add a reference afterwards "in the literature" in Line 104.

 

Thank you for your comment. It's done.

 

In addition, we have made modifications to the language expression of the article.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

After this revision the manuscript is improved. Thus, I am recommending this revised manuscript for publication.

Author Response

Thank you so much for your kind work, careful consideration, constructive suggestions, and approval of our manuscript.