Progress in Research on Coalbed Methane Purification Technology against the Background of Carbon Peak and Carbon Neutrality
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe author presents “Research Progress of Coalbed Methane Purification Technology under the Background of Carbon Peak and Carbon Neutrality”. The manuscript has good findings based on their literature, however, it still lacks some important information needed to describe this work in a more effective way to publish in Processes. Therefore, I suggest a major revision of the manuscript based on the following points listed below:
Comments:
Considering the carbon neutrality, it is important to discuss all the emission sources which needs to be lessened, in the introduction. In this point of view, global warming and greenhouse gases issues is one of the main source, which should be considered, I suggest authors to add few sentences on the CO2 capture and utilization in addition to methanation. Considering this point it is necessary to cite the recent published papers; Appl. Catal. B: Environ., 338 (2023) 123052; and Topics in Catal., 67 (2024) 363-376.
What is the novelty of this work? The author should describe clearly in the introduction section.
Figure 2 is too blurred. This quality of images should be improved.
Why pressure swing adsorption separation is used? What are its advantages and disadvantages. The author should considered this point.
Line 105, author starts from 1986 to discuss about the PSA technology. Its better to draw a timeline and the modifications from 1986 to 2024, to better understand.
In Fig. 6, why the catalytic stability of the catalyst is too low. Considering the industrial applications, author should consider this point.
The conclusions should discussed about their findings, the current version is insufficient to depict the whole picture of the contribution of this study. The conclusion should be revised based on their own findings from the literature.
Comments on the Quality of English Language
The manuscript requires moderate English editing
Author Response
Dear Editor and Reviewers,
The authors would like to thank Editor and Reviewers for comments to improve the quality of the paper. Your comments will be of great help to our future thesis writing. We have studied comment carefully and have made correction. The revised content has been marked in the text. You may need to use the "show comments" function under "review" in Microsoft Word. Looking forward to your approval.
Thank you.
Considering the carbon neutrality, it is important to discuss all the emission sources which needs to be lessened, in the introduction. In this point of view, global warming and greenhouse gases issues is one of the main source, which should be considered, I suggest authors to add few sentences on the CO2 capture and utilization in addition to methanation. Considering this point it is necessary to cite the recent published papers; Appl. Catal. B: Environ., 338 (2023) 123052; and Topics in Catal., 67 (2024) 363-376.
reply：Revised as suggested, see Q1. References [8], [9].
What is the novelty of this work? The author should describe clearly in the introduction section.
reply：Revised as suggested, see Q2.
Figure 2 is too blurred. This quality of images should be improved.
reply：Revised as instructed, see the revised Figure 2 in the manuscript, and Figure 4 has also been modified.
Why pressure swing adsorption separation is used? What are its advantages and disadvantages. The author should considered this point.
reply：Revised accordingly, see Q3.
Line 105, author starts from 1986 to discuss about the PSA technology. Its better to draw a timeline and the modifications from 1986 to 2024, to better understand.
reply：Revisions made, see Q4 and S4, with Table 1 and Table 2 added.
In Fig. 6, why the catalytic stability of the catalyst is too low. Considering the industrial applications, author should consider this point.
reply：There was no Figure 6 or mention of catalysis in the original draft.
The conclusions should discussed about their findings, the current version is insufficient to depict the whole picture of the contribution of this study. The conclusion should be revised based on their own findings from the literature.
reply：Conclusion has been revised. I have incorporated key research findings into the Conclusions section.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for Authors
In this work, the authors provide a review on coalbed methane purification, reviewing and focusing on the mechanism of adsorption in pressure swing adsorption. However, the work lacks criticality, and in major parts very elementary. The work mentions carbon peak and neutrality however, this connection is not clear in the work. The review of the literature is limited and missing the material aspect, which is key for adsorption. This work can not be published din its current form.
1. Line 11 in the abstract, which government, the statement is very broad and needs to be re-written.
2. Line 18 in the abstract, which two processes, only one is mentioned.
3. Overall, the abstract is not well-written, with the majority focused on the background of the work rather than the novel results and main highlights from the work. The bulk of the abstract should be cantered on the work and the new results obtained.
4. Line 41, the range is very broad, do you have more specific data to narrow down the range, or at least add a statement to justify the broad range, if based on the type of bedrock, etc.
5. In lines 57-59, the scope and novelty of the work are missing. What is this work focusing on, and what does it aim to deliver?
6. Schematics for section 2 on PSA are missing. Also, key to PSA is the choice of adsorbent, which is not considered.
7. Section 3 is also very broad, several aspects are missing:
a. Preferential adsorption based on intermolecular interactions
b. Selectivity and effect of impurities on adsorption capacity
c. Role of material in selective adsorption
d. Wishlist of key material properties for effective methane adsorption
8. The review of literature in section 3 lacks criticality, what were the main outcomes in terms of adsorption quantity, energy requirements, effect of impurities, other interesting outcomes. The same comment applies to sections 4 and 5.
9. Carbon peak and neutrality is mentioned throughout the text and in the title, however, this has not been shown critically in the manuscript or its connection to the core elements of the work.
Comments on the Quality of English Language
Minor changes, but can be dealt with by careful proofreading.
Author Response
Dear Editor and Reviewers,
The authors would like to thank Editor and Reviewers for comments to improve the quality of the paper. Your comments will be of great help to our future thesis writing. We have studied comment carefully and have made correction. The revised content has been marked in the text. You may need to use the "show comments" function under "review" in Microsoft Word. Looking forward to your approval.
Thank you.
- Line 11 in the abstract, which government, the statement is very broad and needs to be re-written.
Reply: The abstract has been fully revised.
- Line 18 in the abstract, which two processes, only one is mentioned.
reply：The original statement indeed had errors. Corrected, see R2. Thank you.
- Overall, the abstract is not well-written, with the majority focused on the background of the work rather than the novel results and main highlights from the work. The bulk of the abstract should be cantered on the work and the new results obtained.
reply：Revised following your suggestion, thank you.
- Line 41, the range is very broad, do you have more specific data to narrow down the range, or at least add a statement to justify the broad range, if based on the type of bedrock, etc.
reply：Revised, see R4.
- In lines 57-59, the scope and novelty of the work are missing. What is this work focusing on, and what does it aim to deliver?
reply：Revised, see Q2.
- Schematics for section 2 on PSA are missing. Also, key to PSA is the choice of adsorbent, which is not considered.
reply：Added Figure 3 and Figure 6 as suggested, see S2, S3.
Regarding adsorbents, equilibrium effect-based separations predominantly employ activated carbon, whereas kinetic effect-based separations favor the use of carbon molecular sieves (CMS) and zeolite molecular sieves. See R5 and R6 for details.
- Section 3 is also very broad, several aspects are missing:
- Preferential adsorption based on intermolecular interactions
- Selectivity and effect of impurities on adsorption capacity
- Role of material in selective adsorption
- Wishlist of key material properties for effective methane adsorption
reply：Preferential adsorption based on intermolecular interactions，see R7.
Preferential adsorption based on intermolecular interactions，see R8.
Role of material in selective adsorption and Wishlist of key material properties for effective methane adsorption，see R9.
- The review of literature in section 3 lacks criticality, what were the main outcomes in terms of adsorption quantity, energy requirements, effect of impurities, other interesting outcomes. The same comment applies to sections 4 and 5.
reply：Revised as suggested, see R10, R11.
- Carbon peak and neutrality is mentioned throughout the text and in the title, however, this has not been shown critically in the manuscript or its connection to the core elements of the work.
reply：In the methane industry, carbon reduction efforts mainly focus on the coal industry, where the challenge lies in the low concentration of methane in coal mine gas emissions during mining. Current applications for low-concentration coal mine gas include power generation and thermal oxidation, but their impact on carbon reduction is limited due to the low methane content. Pressure swing adsorption for methane concentration enhancement has become a recent focal point. Revisions made, see R12 and Q2.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsThe author present, “Research Progress of Coalbed Methane Purification Technology under the Background of Carbon Peak and Carbon Neutrality”. The manuscript focused on the progress on the background of carbon neutrality. However, it has many issues which needs to be addressed prior to publication. Therefore, I suggest a major revision of the manuscript based on the following points listed below:
I suggest authors to write a comprehensive abstract. The current version is too long.
The introduction section should incorporate the recent articles regarding CCUS. Here are the few articles which should be cited in the introduction section; ACS Catal., 18 (2020) 10325-10338; Appl. Catal. B: Environ., 338 (2023) 123052; Topics in Catal., 67 (2024) 363-376.
All the images are too blurred. Therefore, I suggest authors to improve he quality of images.
In separation based on counter balance effect, author discuss the history from 1986—2014. How about 2024? Author should incorporate the current status of the separation techniques.
What are the core dynamic effects considering during separation.
There should be Figure regarding the separation apparatus in the article.
I suggest authors to add a comparison table based on the separation techniques available in the literature.
The conclusions is too general to depict the whole picture of paper. The authors should modify the conclusion including their industrial applications.
Comments on the Quality of English LanguageThe manuscript needs English editing
Author Response
Dear Editor and Reviewers,
The authors would like to thank Editor and Reviewers for comments to improve the quality of the paper. Your comments will be of great help to our future thesis writing. We have studied comment carefully and have made correction. The revised content has been marked in the text. You may need to use the "show comments" function under "review" in Microsoft Word. Looking forward to your approval.
Thank you.
I suggest authors to write a comprehensive abstract. The current version is too long.
The introduction section should incorporate the recent articles regarding CCUS. Here are the few articles which should be cited in the introduction section; ACS Catal., 18 (2020) 10325-10338; Appl. Catal. B: Environ., 338 (2023) 123052; Topics in Catal., 67 (2024) 363-376.
reply：The abstract section has been revised, see S1, references [7], [8], [9].
All the images are too blurred. Therefore, I suggest authors to improve he quality of images.
Reply: All right, modifications have been made.
In separation based on counter balance effect, author discuss the history from 1986—2014. How about 2024? Author should incorporate the current status of the separation techniques.
reply：As shown in Table 1 and Table 2, separation based on equilibrium effects was initially developed and applied. Since 2014, techniques based on kinetic effects have dominated, primarily due to their lower overall energy consumption in engineering applications and reduced usage of molecular sieve preparation. See R11 for further explanation.
What are the core dynamic effects considering during separation.
reply：In the adsorption process, considerations include the migration rate of the mass transfer zone front, residual concentrations of the adsorbed gas components in the top product, and during regeneration, the composition of the bottom outlet gas. Additionally, given the safety concerns with oxygen-containing waste gas, attention must be paid to temperature increases due to the heat of adsorption effect, necessitating monitoring of the outlet gas temperature at the top of the column.
There should be Figure regarding the separation apparatus in the article.
reply：Figures 3 and 6 have been added as suggested, see S2, S3.
I suggest authors to add a comparison table based on the separation techniques available in the literature.
reply：Revisions completed, see Q4 and S4, with Tables 1 and 2 included.
The conclusions is too general to depict the whole picture of paper. The authors should modify the conclusion including their industrial applications.
reply：The 'Conclusions' section has been revised.I have incorporated the more crucial research findings into the Conclusions.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe revision is acceptable
Author Response
OK, thank you.
Reviewer 2 Report
Comments and Suggestions for Authorsthe authors have addressed the comments in a good way.
Please add this article (DOI: https://doi.org/10.1016/j.jcou.2022.102383) in the introduction to open the future direction for exploring this type of material for the application.
Author Response
OK, thank you. The literature proposes the use of mixed adsorption materials to increase the adsorption capacity of molecular sieves, which is indeed a future research direction for PSA. Added, see reference [26].
Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper can be published now
Comments on the Quality of English LanguageCan be improved little more
Author Response
OK, thank you. I have made some modifications to the English language, please refer to the red section of the revised manuscript for details.
