Operando Dual Beam FTIR Study of Hydroxyl Groups and Zn Species over Defective HZSM-5 Zeolite Supported Zinc Catalysts
Round 1
Reviewer 1 Report
The paper is very interesting and can be published. But the figs could be modified and should be more visible and understandable. My opinion that article can be published after changing the view of the figs.
Author Response
Dear reviewer,
Thank you very much for your nice comments and constructive suggestions for improving the quality of our manuscript.
According to these suggestions, we have made thorough revision on the manuscript, and carefully responded all the comments point-by-point. After this revision, we believe the quality of this paper has been markedly improved. We wish the revised paper can satisfy you, and be published as soon as possible in cataslysts.
Thanks for your consideration!
Sincerely yours,
Jiaxu Liu (corresponding author) and Long Lin (first author)
liujiaxu@dlut.edu.cn
State Key Laboratory of Fine Chemicals, School of Chemical Engineering,
Dalian University of Technology, Dalian 116024, China
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This work describes the effect of Zn incorporation to the zeolite framework with different Si/Al ratio and hence the different acidity on the catalytic performances during dehydrogenative aromatization of n-hexane. The manuscript shows very well-organized characterizations, but the quality of scientific interpretation and discussion is greatly deficient. At the starting stage of the manuscript, the authors undertook the current work with series of ZSM-5 zeolites having defective sites. They stated that the defective sites were intentionally prepared. However, it is very unclear how the authors prepare the series of ZSM-5 zeolites with systematic control of defective sites. In the experimental section, the authors only mentioned that they synthesized the zeolite series by company. The preparation of the samples and their characterization with scientific means are the most important part in this work before going to the details. This should be clarified in more detail. Depending on the preparation route and the characterization, the other result parts can be significantly affected, which means that the conclusion can also be changed.
In particular, the authors showed various characterization data for the samples. They analyzed FT-IR to provide the evidence of nest silanol sites as defective sites. In addition, the authors analyzed the acidity by using ammonia TPD. There is very interesting situation in ammonia TPD. In Fig. S1b, the authors compared the ammonia TPD for Z55 and Z80 samples. Why the intensity for Z55 is much lower than that for Z80? The intensity of peak and its corresponding integrated area should be proportional to the amount of aluminum, and therefore it might be reasonable to think that the Z55 sample should show larger peak area than Z80. However, it is not. Is there any special reason for this phenomenon?
The authors suggest that Zn2+ is the main type of zinc species in the samples modified by Zn(C2H5)2 according to reference 36. However, there is no characterization results to prove that Zn2+ is the main type of zinc species in the samples prepared in this work. Joseph et al revealed that (ZnOH)+ species are not thermally stable and that they undergo dehydration, by coupling of (ZnOH)+ species with acidic OH groups to form water and a bridging Zn2+ cation by X-ray absorption analysis. However, no evidence or published literatures regarding the presence of Zn2+ are not provided clearly in this work.
As the final issue, the title of the current manuscript looks too much overestimated compared to the real worth of this work. This article is focusing on the effect of Zn incorporation to the zeolite framework on the catalytic performance. The “Insights into the nature” in the title looks somewhat broader than the content of the current work.
In summary, the current work is not providing the most important parts, i.e., preparation and characterization of the series of zeolites with controlled defective sites. This is the starting stage before going to the detailed researches on the catalytic performances. If the synthesis and characterization are changed, the catalytic interpretation and conclusion parts can totally be changed. Accordingly, the manuscript should be fully revised with great care. After then, the manuscript can be re-evaluated for publication.
Author Response
Dear reviewer,
Thank you very much for your nice comments and constructive suggestions for improving the quality of our manuscript.
According to these suggestions, we have made thorough revision on the manuscript, and carefully responded all the comments point-by-point. After this revision, we believe the quality of this paper has been markedly improved. We wish the revised paper can satisfy you, and be published as soon as possible in cataslysts.
Thanks for your consideration!
Sincerely yours,
Jiaxu Liu (corresponding author) and Long Lin (first author)
liujiaxu@dlut.edu.cn
State Key Laboratory of Fine Chemicals, School of Chemical Engineering,
Dalian University of Technology, Dalian 116024, China
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors revised manuscript with great care, and the revised version looks much better than the original one. The manuscript will attract many potential readers involved in this research theme, and therefore I recommend the publication of this work in this journal.
