Recent Advances in Catalysis for Methanation of CO2 from Biogas
Round 1
Reviewer 1 Report
Referee report to Catalysts:
Manuscript ID: Catalysts-1653931
Title: Recent advances in catalyst studies for direct CO2 methanation from biogas
Authors: Selina Niess*, Udo Armbruster, Sebastian Dietrich and Marco Klemm
Summary: The review of Niess et al. deals with the sieving of Ni based catalysts suitable for the methanation of CO2 using direct biogas as feed by evaluating the influence of methane and catalyst poisons like H2S in the feed. The work of Niess et al. is an excellent review of 101 papers dealing with methanation of biogas. The existing knowledge on the thermo-catalytic methanation of biogas using Ni based catalysts was summarized using 9 figures and 18 tables. Suitable catalysts, especially, Ni based systems were identified, for the methanation of CO2 in the biogas, that have the capacity to overcome the challenges posed by catalyst poison as well as high concentration of methane in the feed biogas. High methane content of biogas has a significant impact on the reaction equilibrium and on the conversion of CO2. The synergy between the active component, support, and promoters for the methanation of CO2 from biogas and the resistance of the catalyst from S poisoning were discussed. Though a web of Science search with the keywords, namely, biogas and methanation and catalysis, shows 2 results, none of them dealt with the new insights provided by Niess et al. Owing to the originality and the usefulness of the review, the work of Niess et al. is recommended for publication in the journal Catalysts after minor revision.
Major issues: None
Minor issues: English language needs improvement throughout the manuscript. Subscripts and superscripts to be properly written. The names of Chinese authors need to be cited properly. In addition, the following specific changes can be considered while revising the paper.
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Revision |
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2 |
Rewrite the title as “Recent advances in catalysis for methanation of CO2 from biogas”
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14 |
Replace “against” with “to”
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27 |
Add “that is” before “considered”
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1213 |
If available, the English translation of reference 2 can be provided
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1215 |
Replace “CO2” with “CO2”
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1246 |
Replace “Arespacochaga, N. de” with “de Arespacochaga, N”
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1219 |
Replace “C. –H.” and “C. –S.” with “C. H.” and “C. S.” respectively
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1226 |
Replace “Li, C.” and “Yang, Y.;” with “Li, C. E.;” and “Yang, Y. X.;” respectively
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1228 |
Replace “F. –Z.” with “F. Z”
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1231 |
Reference 12 is retracted and need to be deleted
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1249 |
Replace “su lfur” with “sulfur”
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1267 |
Replace “Yang, L.; Ge, X.; Wan, C.; Yu, F.; Li, Y.” with “Yang, L. C.; Ge, X. M.; Wan, C. X.; Yu, F.; Li, Y. B.’
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1273 |
Replace “Li, W.; Wang, H.; Jiang, X.; Zhu, J.; Liu, Z.; Guo, X.; Song, C.; with “Li, W. H.; Wang, H. Z.; Jiang, X.; Zhu, J.; Liu, Z. H.; Guo.; X. W.; Song, C. S.;”
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1281 |
Replace “Zheng, L” with “Zheng, L. R.;”
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1288 |
English version of the reference to be provided
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1289 |
Replace “Li, H.; Yu, Z.;” with “Li, H. L.; Yu, Z. X.;”
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1291 |
Replace “Yue, J.; Cui, Y.; Xu, G.;” with “Yue, J. R.; Cui, Y.B.; Xu, G. W.;”
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1294 |
Replace “CO2” with “CO2”
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1296 |
Replace “Gao, J.; Liu, Q.; Gu, F.; Liu, B.; Zhong, Z.; Su, F.;” with “Gao, J. J.; Liu, Q.; Gu, F. N.; Liu, B.; Zhong, Z. Y.; Su, F. B.;”
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1312 |
Replace “CO2” with “CO2” Apply this change throughout the review Subscripts and superscripts to be properly written
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1317 |
Replace “Liu, C. –j.; Ye, J.; Jiang, J.; Pan, Y.” with “Liu, C. J.; Ye, J. Y.; Jiang, J. J.; Pan, Y. X.;”
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1319 |
Replace “-M” with “M”
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1330 |
Replace “-N” with “N”
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1334 |
Replay “-Y” and “-C” with “Y” and “C”
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1356 |
Replace “Yan, X.; Liu, Y.; Zhao, B.; Wang, Y.; Liu, C. –j.;” with “Yan, X. L.; Liu, Y.; Zhao, B. R.; Wang, Y.; Liu, C. J.;”
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1358 |
Replace “-j” with “J”
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1360 |
Replace “Yan, X.; Liu, Y.; Zhao, B.; Wang, Z.; Wang, Y.; Liu, C. –j.;” with “Yan, X. L.; Liu, Y.; Zhao, B. R.; Wang, Z.; Wang, Y.; Liu, C. J.;”
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1387 |
Replace “CO2” with “CO2”
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64 |
Reference 12 is retracted. This can be deleted.
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553 |
Reference 12 is retracted. This can be deleted. Reference 12 can be replaced with appropriate reference so that the reference numbers of others will remain unchanged
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33-34 |
Delete “bound thousands of years ago.”
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83 |
Add “poisons” after “those”
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744 |
Replace “Discussion of methane effect in feed” with “Discussion on the effect of methane in the feed”
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1100 |
Replace “Discussion of H2S effect in feed” with “Discussion on the effect of H2S in the feed”
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106-107 |
Delete “used for the process”
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147 |
The sentence “Apart from siloxanes, these components have a corrosive effect …. Equipment.” is unclear. Are “siloxanes” corrosive or not?
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136-1185 |
Owing to constraint with time the text in these lines could not be read line-by-line but was only glanced through and the authors are advised to correct for English language and other errors, if any, to avoid another revision.
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Comments for author File: 
Comments.pdf
Author Response
English language was reviewed and improved throughout the manuscript.
The superscript and subscript of characters was also checked.
The names of the Chinese authors were adapted and approved by a Chinese colleague.
Specific suggested changes by the reviewer were considered, including the title.
Reviewer 2 Report
The present manuscript reports the state-of-the art of the direct CO2 methanation from biogas over different catalysts. I found manuscript very interesting, well-discussed and with a comparative high importance regarding to CO2 storage, utilization and fixation. Therefore, the manuscript can be accepted with minor revision.
- In the section of 6.5, is it possible to include the thermodynamic equilibrium analysis of CO2 methanation in the presence of CH4? This will provide a basic understanding the effect of CH4 content in CO2 methanation.
Author Response
In Section 6.5, a thermodynamic equilibrium analysis of CO2 methanation in the presence of two different CH4 concentrations was added.
English spelling was checked and minor adjustments were made.
