Selective Hydrogenolysis of Tetrahydrofurfuryl Alcohol to 1,5-Pentanediol over MgAl₂O₄-Modified Pt/WO₃/γ-Al₂O₃ Catalyst

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The work of Wang and Chen discusses new results for the hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol over Mg/Al-modified Pt/W/alumina catalysts. The work is interesting and comprehensive covering many topics and deserve publication, in my view.

However, the authors are encouraged to look after a number of topics before its acceptance:

1. Introduction. The uses of 1,5-PeD are not complete. Check important uses and update the text, such as plasticizer, polyesters, emulsifying agents, resin intermediates. Have a look at industrial chemistry books, such as Ullmann´s encyclopaedia: (https://onlinelibrary.wiley.com/doi/book/10.1002/14356007)

2. Use of decimals. The authors should be careful with the use of significant decimals along the text:

a) Pore size diameter (Table 1). One decimal is enough. I don´t think that two decimals can be obtained from the data shown in the isotherms.

b) Total acid content (Table 1). No need to have decimals, round the values as integers. The error from the apparatus is higher than one decimal in the values.

c) Same for Pt dispersion. No need to have decimals in Table 2 and text (line 137).

d) Line 136. It should be 40.5 rather than 40.45.

3. Page 2. The statement to replace Rh and Ir by Pt towards implementation is very interesting but it can be supported by adding a reference such as this one below, which discusses the crucial steps towards the commercialization of catalytic materials:

https://doi.org/10.1021/acs.iecr.1c02681

4. Mg-Alumina spinel. The authors comment about the spinel (title, abstract, keywords) but this is not seen by XRD (Figure 1). In fact, the authors do not discuss the spinel in the results/discussion section (section 2). My suggestions are:

a) to remove the term spinel from the manuscript (title, abstract, keywords) because the spinel formation is not proven.

b) you may state the following in line 80, before ´Upon the introduction …´: ´We are assuming that a very dispersed MgAl2O4 phase is formed, undetectable by XRD´.

5. Line 91 replace ´structural´ by ´textural´.

6. Page 3. Porosity characterization. This part requires some improvements as follows:

a) replace ´Langmuir´ by ´IUPAC´ in line 104.

b) Reference 21 is not suitable. You can remove it and add these references instead, closely related to porosity:

https://doi.org/10.1016/j.scriptamat.2020.113679

https://doi.org/10.1515/pac-2014-1117

c) Line 106. There is no need to add reference 22 because type IV is originating from a mesoporous material (type IV). This reference can be removed.

7. Figure 2. Y axis, remove the units and add a.u. for arbitrary units.

8. BET decrease. Because the pore size remains constant, it means that some pores are blocked and other open. Therefore, the coating effect does not seem to be present (check this interpretation). In addition, the decrease in BET can be originating from the microporosity that decreases. Please check the microporosity using e.g. the t-plot method and add the values in Table 1.

9. TEM interpretation, line 151. TEM spectra reveal a more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst. However, this is contradictory with the distributions shown in Figure 3, where the particle size is more uniform for the Pt/WAl. I suggest to remove the last part of the sentence, from “ … and the TEM spectra further reveal a more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst.”

10. There is no need to mention the equipments used for the characterizations in the Results and discussion. This is already mentioned in the experimental section.

11. Line 164. This is contradictory to the experimental section: where y% represents the mass ratio of MgAl2O4 to WAl (y = 0, 6, 12, 18). In the experimental section, it is stated that ´y´ is the percent not the ratio. Clarify this please.

12. In the experimental section and in the text, please clarify if the % of MgAl2O4 is wt.%. I refer to ´y´, Figure 5b and Figure 5d.

13. Line 199. Why the distribution of W species is claimed to be important?

14. Are the catalytic performance data reported in Table 3 obtained at certain time? Please clarify.

15. Discussion. Line 227. I do not agree that the MgAl2O4 modification significantly impacts the crystal structure. The XRD are quite similar. Texture and acidity changes and XRD shifts a bit. Therefore, I suggest to remove ´XRD´ from the sentence as well as ´crystal structure´.

16. Experimental section. Catalyst preparation. There are some aspects to be corrected:

a) replaced ´roasted´ by ´calcined´ in several places.

b) line 267. ´yMgAl2O4@WAl´ should be ´6MgAl2O4@WAl´.

c) line 271. This sentence should be removed ´The resulting product was the MgAl2O4-modified WAl carrier, with 6% MgAl2O4 by mass incorporated into the WAl carrier.´ This is because the synthesis of this material was described above already, and here you are discussing the other materials.

d) Please specify if the % of Pt is wt %.

17. In the abstract.

a) Line 14. The lowering of the acidity should be mentioned.

b) Line 16. This sentence below is not fully correct: ´These alterations significantly influenced catalyst performance.´ In fact, the authors do not know what is causing the improvement yet. I suggest to rephrase this sentence as: ´These alterations appear to influence the catalyst performance, though other factors cannot be ruled out´.

Comments on the Quality of English Language

I did not notice anything to be corrected.

Author Response

1. Introduction. The uses of 1,5-PeD are not complete. Check important uses and update the text, such as plasticizer, polyesters, emulsifying agents, resin intermediates. Have a look at industrial chemistry books, such as Ullmann´s encyclopaedia: (https://onlinelibrary.wiley.com/doi/book/10.1002/14356007)

Response to Question 1: Thank you for your feedback on the manuscript. I have carefully reviewed the introduction section and updated the description of the uses of 1,5-pentanediol (1,5-PeD) to include the important applications you mentioned.

 

2. Use of decimals. The authors should be careful with the use of significant decimals along the text:
3. a) Pore size diameter (Table 1). One decimal is enough. I don´t think that two decimals can be obtained from the data shown in the isotherms.
4. b) Total acid content (Table 1). No need to have decimals, round the values as integers. The error from the apparatus is higher than one decimal in the values.

Response to Question 2: Thank you for your feedback on the use of decimals in our manuscript. I have carefully reviewed the document and made the necessary adjustments to adhere to your suggestions.

Regarding the specific points you mentioned:

1. a) Pore size diameter (Table 1): I have revised the table to include only one decimal place for the pore size diameter, as you suggested. This reflects the accuracy of the data obtained from the isotherms.
2. b) Total acid content (Table 1): I have rounded the values for total acid content to integers, as you recommended. This adjustment acknowledges the error range of the apparatus, which exceeds one decimal place.
3. c) Pt dispersion: I have also revised Table 2 and the corresponding text (line 137) to remove any decimals from the Pt dispersion values. This change maintains consistency with the recommended reporting format.
4. d) Line 136: I have corrected the value from 40.45 to 40.5, as you indicated. This adjustment aligns with the revised decimal usage throughout the document.

 

3. Page 2. The statement to replace Rh and Ir by Pt towards implementation is very interesting but it can be supported by adding a reference such as this one below, which discusses the crucial steps towards the commercialization of catalytic materials:

https://doi.org/10.1021/acs.iecr.1c02681

Response to Question 3: Thank you for your thoughtful review of our manuscript and for the valuable suggestion to strengthen our argument regarding the replacement of Rh and Ir by Pt towards implementation. We appreciate your guidance and have carefully considered the recommended reference.

Following your advice, we have now included the cited reference (https://doi.org/10.1021/acs.iecr.1c02681) in our discussion.

 

4. Mg-Alumina spinel. The authors comment about the spinel (title, abstract, keywords) but this is not seen by XRD (Figure 1). In fact, the authors do not discuss the spinel in the results/discussion section (section 2). My suggestions are:
5. a) to remove the term spinel from the manuscript (title, abstract, keywords) because the spinel formation is not proven.
6. b) you may state the following in line 80, before ´Upon the introduction …´: ´We are assuming that a very dispersed MgAl2O4 phase is formed, undetectable by XRD´.

Response to Question 4: Thank you for your valuable feedback on our manuscript. We have carefully reviewed the points raised and made the necessary revisions.

Regarding the issue with the Mg-Alumina spinel, we appreciate your observation that the term "spinel" was mentioned in the title, abstract, and keywords but was not explicitly confirmed by the XRD data (Figure 1). Furthermore, the discussion of the spinel in the results/discussion section was indeed lacking.

To address this concern, we have chosen to adopt your recommendation (b) and have included the following statement in line 80, before "Upon the introduction ...":

"We are assuming that a very dispersed MgAl2O4 phase is formed, undetectable by XRD due to its low concentration or high dispersion within the material."

We believe this addition clarifies our understanding of the possible presence of the MgAl2O4 phase without overstating its confirmed formation. The term "spinel" has been retained in the title, abstract, and keywords to maintain consistency with the context of the study, but with the added qualification in the text to account for its potential undetected nature.

 

5. Line 91 replace ´structural´ by ´textural´.

Response to Question 5: Thank you for pointing out the inconsistency in the use of terminology in our manuscript. I have carefully reviewed the line you mentioned and have made the necessary correction.

As suggested, I have replaced the term 'structural' with 'textural' in line 91 to ensure consistency and accuracy.

 

6. Page 3. Porosity characterization. This part requires some improvements as follows:
7. a) replace ´Langmuir´ by ´IUPAC´ in line 104.
8. b) Reference 21 is not suitable. You can remove it and add these references instead, closely related to porosity:

https://doi.org/10.1016/j.scriptamat.2020.113679

https://doi.org/10.1515/pac-2014-1117

106. c) Line 106. There is no need to add reference 22 because type IV is originating from a mesoporous material (type IV). This reference can be removed.

Response to Question 6: Thank you for your feedback on the porosity characterization section of our manuscript. I have addressed the points you raised as follows:

1. a) I have corrected the terminology in line 104 and replaced 'Langmuir' with 'IUPAC' to conform with the standard classification of isotherms. The revised line now reads: "The IUPAC classification of the isotherms was used to identify the type of porosity."
2. b) I have removed Reference 21 from the manuscript as it is not suitable for the context. Instead, I have included the two references you suggested, which are closely related to porosity characterization. The citations have been inserted appropriately in the text. The new references read:

"[New Reference 1] https://doi.org/10.1016/j.scriptamat.2020.113679

106. c) I agree with your suggestion to remove Reference 22 from line 106. As you mentioned, the classification of type IV isotherms is generally associated with mesoporous materials and does not require a specific reference. I have made the necessary changes in the manuscript.

 

7. Figure 2. Y axis, remove the units and add a.u. for arbitrary units.

Response to Question 7: Thank you for your feedback. We have made the necessary modifications to Figure 2 as per your instructions. The units have been removed from the Y axis, and "a.u." has been added to indicate arbitrary units.

 

 

8. BET decrease. Because the pore size remains constant, it means that some pores are blocked and other open. Therefore, the coating effect does not seem to be present (check this interpretation). In addition, the decrease in BET can be originating from the microporosity that decreases. Please check the microporosity using e.g. the t-plot method and add the values in Table 1.

Response to Question 8: I appreciate your feedback regarding the BET decrease and the interpretation you have provided. Upon further analysis, I would like to clarify and re-explain my understanding of the observed phenomenon.

 

9. TEM interpretation, line 151. TEM spectra reveal a more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst. However, this is contradictory with the distributions shown in Figure 3, where the particle size is more uniform for the Pt/WAl. I suggest to remove the last part of the sentence, from “ … and the TEM spectra further reveal a more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst.”

Response to Question 9: Thank you for your attention to our manuscript. I appreciate your suggestion regarding the TEM interpretation at line 151. As you have pointed out, the statement about the more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst does indeed contradict the information presented in Figure 3.

I have carefully reviewed the relevant section and have removed the last part of the sentence, starting from "... and the TEM spectra further reveal a more uniform distribution of Pt particles on the Pt/12MgAl2O4@WAl catalyst." I believe this change will clarify the point and eliminate the inconsistency you have identified. 

 

10. There is no need to mention the equipments used for the characterizations in the Results and discussion. This is already mentioned in the experimental section.

Response to Question 10: Thank you for your valuable feedback on our manuscript. I have carefully reviewed the part you mentioned regarding the mention of equipment used for characterizations in the Results and Discussion section. As you pointed out, this information is already detailed in the Experimental section.

To avoid redundancy and keep the manuscript concise, I have removed the repeated mention of the equipment used for characterizations from the Results and Discussion section.

 

11. Line 164. This is contradictory to the experimental section: where y% represents the mass ratio of MgAl2O4 to WAl (y = 0, 6, 12, 18). In the experimental section, it is stated that ´y´ is the percent not the ratio. Clarify this please.

Response to Question 11: Thank you for highlighting the inconsistency in the representation of variable 'y' in our manuscript. After reviewing the experimental section, we have realized that the use of 'y%' to represent the mass ratio of MgAl2O4 to WAl may have caused confusion.

To clarify, in the experimental section, 'y' is indeed intended to represent the percentage (not ratio) of MgAl2O4 in the composite material relative to the total mass of MgAl2O4 and WAl. Specifically, when y = 0, it means there is no MgAl2O4, and when y = 6, it means 6% of the total mass is MgAl2O4, and so on.

 

12. In the experimental section and in the text, please clarify if the % of MgAl2O4 is wt.%. I refer to ´y´, Figure 5b and Figure 5d.

Response to Question 12: Thank you for your feedback on our manuscript. I have carefully reviewed the experimental section and the text in regard to the percentage of MgAl2O4 and clarified the usage of "%" as weight percent (wt%).

Specifically, regarding the symbol 'y' in the text, I have explicitly stated that it represents the weight percentage of MgAl2O4 in the composite. Furthermore, in Figure 5b and Figure 5d, where percentages are mentioned, I have added a note to clarify that the percentages refer to weight percentages (wt%).

 

13. Line 199. Why the distribution of W species is claimed to be important?

Response to Question 13: Thank you for pointing out the potential ambiguity in our previous submission. You are correct in noting that our description regarding the importance of the distribution of W species may have been too direct in suggesting a direct correlation with catalyst performance. Our research did not explicitly demonstrate the direct influence of W valence states on the performance of the catalyst.

To clarify and ensure the accuracy of our work, we would like to remove the portion of the text that suggests such a direct connection. We appreciate your feedback, which has helped us strengthen the rigor and clarity of our work.

 

14. Are the catalytic performance data reported in Table 3 obtained at certain time? Please clarify.

Response to Question 14: Thank you for your inquiry regarding the catalytic performance data reported in Table 3. The data presented in Table 3 were indeed obtained at a specific time during the reaction process. Specifically, the samples were analyzed and the corresponding catalytic performance metrics were recorded at the 30th hour of the reaction.

 

15. Discussion. Line 227. I do not agree that the MgAl2O4 modification significantly impacts the crystal structure. The XRD are quite similar. Texture and acidity changes and XRD shifts a bit. Therefore, I suggest to remove ´XRD´ from the sentence as well as ´crystal structure´.

Response to Question 15: Thank you for your valuable feedback on our manuscript. I appreciate your observation regarding the discussion of the MgAl2O4 modification and its impact on the crystal structure.

Upon careful consideration, I agree that the current data from the X-ray diffraction (XRD) analysis do not conclusively demonstrate a significant change in the crystal structure as a result of the MgAl2O4 modification. The XRD patterns, while showing some shifts, are largely similar, indicating that the texture and acidity changes, rather than a fundamental alteration in the crystal structure, are the primary factors affecting the catalytic performance.

As such, I have revised the discussion accordingly, removing the mention of "XRD" and "crystal structure" from line 227.

 

16. Experimental section. Catalyst preparation. There are some aspects to be corrected:
17. a) replaced ´roasted´ by ´calcined´ in several places.
18. b) line 267. ´yMgAl2O4@WAl´ should be ´6MgAl2O4@WAl´.
19. c) line 271. This sentence should be removed ´The resulting product was the MgAl2O4-modified WAl carrier, with 6% MgAl2O4 by mass incorporated into the WAl carrier.´ This is because the synthesis of this material was described above already, and here you are discussing the other materials.

Response to Question 16: Thank you for your feedback on the manuscript. I have carefully reviewed the "Experimental section" and made the necessary corrections as follows:

1. a) I have replaced the term 'roasted' with 'calcined' in all the appropriate places to ensure consistency with the terminology used in the field.
2. b) In line 267, I have corrected the notation from 'yMgAl2O4@WAl' to '6MgAl2O4@WAl' to accurately reflect the composition of the material.
3. c) As per your suggestion, I have removed the sentence "The resulting product was the MgAl2O4-modified WAl carrier, with 6% MgAl2O4 by mass incorporated into the WAl carrier." in line 271, as the synthesis of this material was already described earlier in the text, and it was redundant to mention it again in the context of discussing other materials.

 

17. In the abstract.
18. a) Line 14. The lowering of the acidity should be mentioned.
19. b) Line 16. This sentence below is not fully correct: ´These alterations significantly influenced catalyst performance.´ In fact, the authors do not know what is causing the improvement yet. I suggest to rephrase this sentence as: ´These alterations appear to influence the catalyst performance, though other factors cannot be ruled out´.

Response to Question 17: Thank you for your feedback on the abstract. I have made the following revisions to address the points you raised:

1. a) Line 14: I have included a mention of the lowering of acidity in the abstract. The revised line reads: " Characterization revealed that magnesia-alumina spinel modification enhanced Pt particle dispersion, CO adsorption on Pt/WO_x/γ-Al₂O₃, reduced Pt particle reduction temperature, diminished the acid content in the catalysts, and increased surface oxygen vacancy concentration. "
2. b) Line 16: I have rephrased the sentence as suggested to indicate that other factors may be influencing the catalyst performance. The new sentence reads: "While these alterations appear to influence the catalyst performance positively, we acknowledge that other factors cannot be ruled out as potential contributors to the observed improvement."

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The submitted article investigates the catalytic hydrogenolysis of tetrahydrofurfuryl alcohol (THFA) to 1,5-pentanediol (1,5-PeD) using Pt/WOx/γ-Al2O3 catalysts modified with magnesia-alumina spinel. The authors prepared and characterized various catalyst compositions to determine the effect of this modification on catalytic performance. The study reveals that the magnesia-alumina spinel modification enhances Pt particle dispersion, CO adsorption, and surface oxygen vacancy concentration, leading to improved activity and selectivity in the production of 1,5-PeD.

The research successfully demonstrates that magnesia-alumina spinel modification improves the dispersion of Pt particles, CO adsorption, and surface oxygen vacancy concentration, resulting in enhanced catalytic performance. Additionally, the work contributes to Green Chemistry by providing valuable insights into catalyst modification for efficient biomass-derived chemical synthesis, which is crucial for developing sustainable chemical production pathways. Thus, the work builds upon existing studies by focusing on a novel modification of Pt/WOx/γ-Al2O3 catalysts. The reported improvements in catalytic activity and selectivity address an important aspect of green chemistry research.

In summary, while the research presented in the article offers significant contributions to the field of catalytic hydrogenolysis and green chemistry, it requires major revisions before it is suitable for publication in the Journal "Catalysts." Addressing the issues of scalability, industrial relevance, and long-term stability, along with enhancing the clarity of the experimental methodology and figures, will greatly improve the quality and impact of the work.

1. The research lacks a thorough discussion on the scalability and potential industrial applications of the modified catalysts. This is crucial for understanding the practical implications and feasibility of the findings.
2. There is limited discussion on the long-term stability and recyclability of the catalysts in continuous processes, which is essential for assessing their viability in real-world applications.
3. The authors should provide a more detailed discussion on the industrial relevance and scalability of the modified catalysts, including potential challenges and solutions for scaling up the catalyst production and its application in industrial settings.
4. A section discussing the long-term stability and recyclability of the catalysts should be included. This would involve presenting data from additional experiments conducted under continuous flow conditions to evaluate the durability of the catalysts over extended periods.
5. The experimental procedures and conditions should be described in greater detail. This will enhance reproducibility and provide clarity for other researchers attempting to replicate the study.
6. The figures should be enhanced by providing more detailed labels and legends. This will improve the reader's ability to understand and interpret the presented data.
7. Consider including additional figures or diagrams that visually represent the structural and property changes resulting from magnesia-alumina spinel modification. This would help illustrate the key findings more effectively and provide a clearer understanding of the modifications and their impact on catalytic performance.

Comments on the Quality of English Language

Minor editing of English language required

Author Response

1.The research lacks a thorough discussion on the scalability and potential industrial applications of the modified catalysts. This is crucial for understanding the practical implications and feasibility of the findings.

Response to Question 1: Thank you for your feedback on our manuscript. We appreciate your insight and have carefully considered your comments regarding the lack of a thorough discussion on the scalability and potential industrial applications of the modified catalysts.

As per your suggestion, we have added a discussion of this section in the 2.3 Discussion section to address this issue.

 

2.There is limited discussion on the long-term stability and recyclability of the catalysts in continuous processes, which is essential for assessing their viability in real-world applications.

Response to Question 2: Thank you for your valuable comments on our manuscript. With regard to the long-term stability and recyclability of the Pt/WAl catalysts in continuous processes, we appreciate your concern regarding their practical viability.

In our previous studies, we have indeed conducted a detailed investigation on the stability of Pt/WAl catalysts. We found that the catalyst remains stable for at least 1000 hours under continuous operation, demonstrating its excellent durability. However, in the current study, our focus was primarily on improving the activity of the catalyst. As a result, we have limited the stability evaluation to 100 hours to gain a preliminary understanding of its behavior over a shorter timescale.

We recognize that long-term stability is crucial for assessing the practical applicability of the catalyst in real-world applications. Therefore, we plan to extend the stability evaluation in our future work to cover a longer duration, as suggested by your review. This will provide us with a more comprehensive understanding of the catalyst's performance and durability in continuous processes.

 

3.The authors should provide a more detailed discussion on the industrial relevance and scalability of the modified catalysts, including potential challenges and solutions for scaling up the catalyst production and its application in industrial settings.

Response to Question 3: We appreciate the reviewer's insightful comment regarding the industrial relevance and scalability of our modified catalysts. While our catalysts demonstrate promising potential for industrial applications, we recognize that there is still a considerable gap between our current results and actual industrial-scale deployment.

 

4.A section discussing the long-term stability and recyclability of the catalysts should be included. This would involve presenting data from additional experiments conducted under continuous flow conditions to evaluate the durability of the catalysts over extended periods.

Response to Question 4: We appreciate the reviewer's comment regarding the need to discuss the long-term stability and recyclability of the catalysts. While we have presented data on the stability of the catalysts for 100 hours, we recognize that additional experiments under continuous flow conditions for extended periods would provide a more comprehensive understanding of their durability.

Unfortunately, due to the scope and limitations of the current study, we were unable to conduct such long-term stability tests. However, we would like to emphasize that the 100-hour stability test we performed provided valuable insights into the initial stability of the modified and unmodified catalysts. Both catalysts exhibited stable performance over this duration, indicating promising potential for longer-term stability.

To address the reviewer's concern, we plan to conduct additional experiments in the future to evaluate the long-term stability and recyclability of the catalysts under continuous flow conditions. This will allow us to assess their durability over extended periods and determine their suitability for industrial applications. We will also explore potential strategies to improve the stability and recyclability of the catalysts, such as optimizing the synthesis conditions or introducing stabilizing agents.

 

5.The experimental procedures and conditions should be described in greater detail. This will enhance reproducibility and provide clarity for other researchers attempting to replicate the study.

Response to Question 5: Thank you for your valuable feedback on our manuscript. We appreciate your attention to detail and the opportunity to improve our experimental procedures.

Regarding the suggestion to describe the experimental procedures and conditions in greater detail, we have now included a more thorough account of the reaction conditions in the catalyst fixed-bed reactor. Specifically, we have expanded the description to include details such as the reactor temperature, pressure, and catalyst dosage.

 

6. The figures should be enhanced by providing more detailed labels and legends. This will improve the reader's ability to understand and interpret the presented data.

Response to Question 6: Thank you for your valuable feedback on our manuscript. I appreciate your suggestion to enhance the figures, specifically Figure 5(d), by providing more detailed labels and legends. This indeed would improve the reader's ability to understand and interpret the presented data.

 

7.Consider including additional figures or diagrams that visually represent the structural and property changes resulting from magnesia-alumina spinel modification. This would help illustrate the key findings more effectively and provide a clearer understanding of the modifications and their impact on catalytic performance.

Response to Question 7: Thank you for your thoughtful feedback on our manuscript. I understand your concern about the need for additional visual representations to clarify the structural and property changes resulting from magnesia-alumina spinel modification.

Unfortunately, at this stage, we are unable to include additional figures or diagrams to visually represent these changes. However, we recognize the importance of visual aids in effectively communicating our key findings and providing a clearer understanding of the modifications and their impact on catalytic performance.

To address this limitation, we have revised the text to provide a more detailed description of the structural and property changes. We have included additional explanations of the key modifications and their significance in enhancing the catalytic performance. We believe that these revisions, along with the existing figures, will provide readers with a sufficient understanding of our work.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Page 5: If the Pt particle size is in the range of 1-2 nm, the dispersion values should be higher. Please provide an explanation for that or check the dispersion measurements.

 

Comments on the Quality of English Language

The paper is well written and English language good.

There are few minor corrections and modifications required:

 

Page 2 line 46: “to” THFA

Page 2, line 56/57 rather “economically attractive” or “low cost”.

Line 72: “process”

Table 3: “Selectivity”

Author Response

1.If the Pt particle size is in the range of 1-2 nm, the dispersion values should be higher. Please provide an explanation for that or check the dispersion measurements.

Response to Question 1: Thank you for your correspondence regarding the Pt dispersion values. We appreciate your observation that, in the case of Pt particle sizes ranging from 1-2 nm, dispersion values are expected to be higher. In response to your query, we would like to clarify the assumptions and potential factors that may have contributed to the lower dispersion values obtained in our study.

Firstly, it is important to note that our Pt dispersion calculations are based on the assumption that each Pt particle adsorbs one CO molecule. This assumption is widely used in the field of catalysis as a means to estimate the dispersion of metal particles on a catalyst surface. However, in reality, there may be deviations from this idealized scenario.

One potential factor that could explain the lower dispersion values is the presence of larger agglomerates of Pt particles on the catalyst surface. While we aim for uniform Pt particle distribution, the formation of agglomerates is a common occurrence in catalyst synthesis. These agglomerates can reduce the effective surface area available for CO adsorption, leading to lower dispersion values.

Additionally, the chemical adsorption of CO on Pt particles may not be complete, particularly if the Pt particles are not fully reduced. In our experiments, it is possible that some Pt particles were not fully reduced, resulting in a reduced number of active sites available for CO adsorption. This, in turn, would reduce the dispersion values calculated based on the adsorbed CO amount.

In summary, while our Pt dispersion calculations are based on established assumptions, there are potential factors that could contribute to lower dispersion values, including the presence of Pt agglomerates and incomplete Pt reduction. We continue to evaluate our methods and refine our protocols to ensure accurate dispersion measurements in our future studies.

Thank you again for your valuable feedback. We appreciate your attention to our work and look forward to continuing our collaboration in the future.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have duly implemented changes and these have clarified my concerns. One aspect was partly addressed (item 4, first revision). I still think that mentioning spinel can bring confusion to the readers; not seen by XRD. Therefore, my suggestion is to replace ´magnesia-alumina spinel´ by ´MgAl2O4´ in title and abstract. This fits better with the statement made in the XRD section (dispersed MgAl2O4). I leave this topic open to the authors to decide. The problem is that some researchers can react negatively to the spinel claim.

Minor issue. Line 266. Adjust subscripts.

Author Response

1. The authors have duly implemented changes and these have clarified my concerns. One aspect was partly addressed (item 4, first revision). I still think that mentioning spinel can bring confusion to the readers; not seen by XRD. Therefore, my suggestion is to replace ´magnesia-alumina spinel´ by ´MgAl2O4´ in title and abstract. This fits better with the statement made in the XRD section (dispersed MgAl2O4). I leave this topic open to the authors to decide. The problem is that some researchers can react negatively to the spinel claim.

Response to Question 1: I am writing to express my sincere gratitude for your thoughtful feedback on our manuscript. Your comments have been instrumental in improving the clarity and precision of our work.

Regarding your suggestion to replace "magnesia-alumina spinel" with "MgAl2O4" in the title and abstract, we have carefully considered your advice and have implemented the necessary changes. We agree that using the chemical formula "MgAl2O4" will be more accurate and less likely to cause confusion for readers.

We have revised the title and abstract to reflect this change, and have also updated the relevant sections of the manuscript where "magnesia-alumina spinel" was previously used. We have ensured that the term "MgAl2O4" is used consistently throughout the text to maintain clarity and coherence.

We appreciate your attention to this detail and your efforts to ensure that our work is presented in the most accurate and understandable manner possible. We believe that these revisions have strengthened our manuscript and made it more accessible to a wider audience.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article has been thoroughly reviewed by the authors, who have addressed and incorporated all the revisions requested. Therefore, the article is now ready and should be accepted for publication in Catalysts.

Author Response

1.The article has been thoroughly reviewed by the authors, who have addressed and incorporated all the revisions requested. Therefore, the article is now ready and should be accepted for publication in Catalysts.

Response to Question 1: I am writing to express my sincere gratitude for your thorough review of our manuscript. Your valuable feedback has been instrumental in refining our work and making it more precise and impactful.

We have considered your comments and made the necessary changes to ensure that the manuscript meets the highest standards of quality and rigor. We believe that these revisions have strengthened our work and made it more suitable for publication.

Once again, thank you for your time and effort in reviewing our manuscript. 

Author Response File: Author Response.pdf