Review Reports

Round 1

Reviewer 1 Report

An interesting and well-prepared paper.

I have some doubts about the validity of the results. Because it seems to me that the correlations presented are not strong enough. Therefore, the comprehensive coal property index may be misleading.  Possibly, a number of other factors affect the chemical structure of the chars.

However, I find interesting the correlation idea of parent coal-properties and chemical structure of the chars.

Correct "funcation" in Fig 9.

It would be better if the correlation figures are normalized.

Add a short phrase to the conclusions for future research recommendation

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and suggestions as comments in pdf manuscript.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx