NO_x Storage and Reduction (NSR) Performance of Sr-Doped LaCoO₃ Perovskite Prepared by Glycine-Assisted Solution Combustion

Round 1

Reviewer 1 Report

The work is interesting, the materials are characterized satisfactorily including XPS analysis.

However, in English it does not clearly convey what the authors want to say, even the organization of the work is a bit confusing, for example Table 1 is far from the comments.

As regards the catalyst, I believe that we cannot talk about doping as the best perovskite appears to have 50% Sr (LS5).

As regards the aged catalyst, the results of this test are not well explained.

Unfortunately, Strontium is a critical material which harms the sustainability of the process.

The work can be accepted with minor revision because it requires reworking of the text.

The english requires a revision

Author Response

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Reviewer 2 Report

Comments for author File: Comments.pdf

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Reviewer 3 Report

See Attached Word file: Review-Compounds (Luan et al)

Comments for author File: Comments.pdf

Author Response

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Reviewer 4 Report

This manuscript reported about Sr-doped perovskite-type oxides of La1-xSrxCoO3, prepared by the glycine-assisted solution combustion method, for NOx Storage and Reduction (NSR). The authors concluded that the perovskite with 50% of Sr doping exhibited excellent NOx storage capacity within a wide temperature range (200-400 ºC), and excellent stability after hydrothermal and sulphur poisoning due to its larger surface area, superior reducibility, better NO oxidation capacity, and increased surface Co2+ concentration. However, there are still several issues need to be addressed thoroughly before this manuscript can be recommended for publication.

1.     However, there are some studies on this material for NSR already published. Please make the comparison for your samples.

2.     Please correct the Eq. (2). The quality of all figures, especial for Fig. 2, needs to be improved.

3.     The large specific surface area of the catalyst is not the main factor which affects the catalytic performance since the Sr-containing samples have similar BET and are not so high.

4.     The information about the N₂ selectivity need to be added. The gas hourly space velocities (GHSV) using in the activity test conditions should be added.

5.     From O2-TPD author concluded that LS5 sample has higher concentration of surface oxygen species and stronger oxidation properties. However, its surface reactive oxygen as seen from XPS data is less than LS3. Please explain this.

6.     Please explain more in detail the effect of Sr on the sulfur resistance of the catalysts. The acidity properties of these catalysts should be added.

Author Response

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Round 2

Reviewer 3 Report

The authors have significantly improved the manuscript and it can now be published after the 2nd review.

Author Response

Thanks for your positive and constructive comments and suggestions.

Reviewer 4 Report

The authors have provided a new version, but this version still needs to be improved. There are some suggestions to improve this work:

1, Please correct the Eq. (2). There are some studies on this material for NSR already published. Please make the calculation correctly to compare your results with others. Please correct whole manuscript related to the NOx storage capacity.

2, Fig. 2a, b are missing.

3, The authors concluded that “The LS5 catalyst contains a higher amount of surface Co2+, which leads to the formation of oxygen vacancies and improves the NO oxidation capacity of the catalyst, thereby enhancing the NOx storage performance” From which results did the authors support this conclusion? How did the authors determine the amount of oxygen vacancies?

Author Response

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