High Performance of Mn-Doped MgAlOx Mixed Oxides for Low Temperature NOx Storage and Release
Round 1
Reviewer 1 Report
The authors performed a decent investigation on Mn-Mg-Al-oxides for NOx storage and release. Since the results are of great interest for the NOx abatement and since the work seems complete and well documented it deserves publication in this journal. There are two major issues that need attention. One is that figures 5, 6 and 11 are missing in the paper (these are also not included in the supplementary material). The second main issue is Equation (2) on page 4 defining the NOx storage capacity. The units of the terms in the equation should be added. I would suggest to use F instead of V for a flow rate. It seems strange that the heating rate R is included in this equation. 'quality' of catalyst should probably be 'quantity' (or better: 'amount') of catalyst. Please also specify the unit of flow rate (i.e. m^3 STP/s; STP = 0°C, 1 atm). By applying different units you may avoid the factor 22.4 (this is the molar volume; i.e. the number of liters ideal gas per mole at STP) in the equation.
Minor remarks:
Line 47: please improve the wrong combination of words 'behaves considerable activity'
Line 51: please correct 'is one focus of this filed'
Line 99: please add some explanation (or a reference) why and how the addition of CTAB is beneficial in the co-precipitation method.
Line 109: The heading '2.2. Catalysts characterization' should get more space and typed in italics.
Line 148: please add how the soot was prepared and how it was added to the catalyst.
Line 184: consider replacing 'were completely damaged' by 'was completely decomposed'.
Line 196: please add more explanation how the reported mean crystallite size was obtained from the XRD diagrams. Did you use the peak width at half height ? Did you apply any correction for instrumental line broadening ? The peak at 61° shows overlap with the peak at 63°. It seems inaccurate to use the peak at 61°.
Line 209: Add to the caption of Figure 2 the scales (or enlarge the pictures that is becomes possible to see read the scales in the pictures) and also the difference between a and b, c and d, and e and f.
Line 219: 'large surface area' should be 'large surface areas'
Line 221: 'The pore diameter' should probably be 'the volume-averaged pore diameter'.
Line 401: please consider replacing 'The analogous results' with 'Similar results'.
Figures S1, S2 and S3: please specify the flow rate condition (e.g. 'STP').
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work aims to develope a catalyst for NOx storage and release. Authors used a large number of structural methods for describing of catalysts nature. With no doubts obtained results are interesting for chemists who deals with catalysis. I can recommend the paper to be published after some revisions according to the next comments:
1) Novelty and originality of the work should be briefly and clearly articulated in the introduction
2) Why do you use hydrotalcites with different ratio of Mg:Al. As a support Mg:Al=75:25 hydrotalcite was used and with Mn content increasing Mg content was decreased. What is the reason?
3) Why calcination was done at 500 C?
4) One of the main problems of the catalytic converters is thermal stability. Developed catalyst crushes at temperature higher than 600 C. Is it suitable for application as a catalytic converter? And the second question is a mechanical stability of the catalyst?
5) Conclusions should be completed with brief comparison of the developed catalyst with modern analogues that are used in industry.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript entitled “High performance of Mn-doped MgAlOx mixed oxides for low temperature NOx storage and release” deals with synthesis, characterization and application of manganese containing catalysts.
The introduction is concise, containing most of important references on the field.
Hypotheses are set and work carried out accordingly.
Results are well described and conclusions in accordance with hypotheses posed.
I just have one remark:
In discussion, the manuscript would highly benefit from a comparison between literature results and the herein reported. A table would be a good addition for the manuscript, together with a discussion on the actual state of the art.
Minor
All acronyms and abbreviations should be defined at first appearance.
Table 2: where is Textual, should be textural
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 4 Report
I found interesting to read this article. This article is very well written and supported by the experimental evidences. Author investigated NOx storage and reduction at low temperature using Mn-doped hydrotalcites derived oxides (Mn/MgAlOx). Author found that hydrotalcites derived oxides with more Mn content showed good properties.
The content is good and novel and hence I recommend its publications in after minor revision.
1. A small corrections, in page 2 line 46 please replace the at el. by et al.
2. Please add a table to compare the NOX storage capacities of all these materials reported here with State-of-art materials.
Thank you
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Dear authors,
thank you for your response. I totally agree with you and the revised version of the manuscript should be accepted, from my point of view.
