Ammonia Decomposition over Ru/SiO2 Catalysts
Round 1
Reviewer 1 Report
This paper aims to enhance the performance of catalytic hydrogen production by preparing Ru/SiO2 catalysts. Experimental results show that the Ru/SiO2 catalyst with a high-surface area achieved the highest ammonia conversion. Moreover, it is shown that the ammonia decomposition is a structure-sensitive reaction. However, some important issues should be addressed. Therefore, I would like to recommend its acceptance by the journal after a minor revision as follow.
1, I am confused about the abbreviations of “Ru/SiO2(SC)” and “Ru/SiO2(C)”. Please define them more specifically.
2, It seems that both the particle size and the catalytic performance for ammonia decomposition of Ru/SiO2(C) are obviously superior than those of Ru/SiO2(SC). Why study these Ru/SiO2(SC) samples for comparison?
3, The authors claimed that the large Ru agglomerates are not plausible for ammonia decomposition. Meanwhile, they found that the larger 6 nm sized Ru particles perform better than the smaller 2 nm sized ones. Which particle size is most suitable for improving the catalytic activity of catalysts for ammonia decomposition?
4, Why the Ru particle size and catalytic activities of Ru/SiO2(C300), Ru/SiO2(C500), and Ru/SiO2(C700) are similar and obviously different from the Ru/SiO2(C100) sample? Please explain it. It is not sufficient to support the notion that ammonia decomposition is a structure-sensitive reaction.
5, Please compare the catalytic performance of Ru/SiO2 catalysts for ammonia decomposition with other reported metal oxide supported metal nanoparticles, rather than only showing the comparison with Ru/Al2O3.
6, Both the ammonia production and hydrogen evolution reactions affect the efficiency of ammonia decomposition. The recent studies about the two reactions should be cited in Introduction. For example, National Science Review 2021, 8, nwaa213; Nano Energy 2021, 89, 106333; CCS Chem. 2022, Just Published. DOI: 10.31635/ccschem.022.202202328; Exploration 2021, 1, 20210050.
7, Some sentences are too long to understand. For example, the sentence in Line 111, 112, 118, and 120.
Author Response
We appreciate the reviewer's kind and valuable comments. Please see the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this work, the author prepared Ru/SiO2 catalyst via calcination at different temperatures for catalytic ammonia decomposition. I recommend this article for publication after some revison.
1. Throughout this article, the author mentioned a few times that the finding supports the notion that ammonia decomposition is a structure-sensitive reaction. However, the particles prepared in this paper all had the same spherical shape and the difference between them is the size. In my opinion, the results in the paper are insufficient to prove the reaction is "structure-sensitive".
2. The experimental part about catalyst preparation needs more detailed information. For example, what is the loading of the catalyst on the support? What is the precursor impregnation process?
3. All the catalysts were calcined and then reduced in H2 for 3h. Is this enough to reduce all the catalysts? Are all the Ru in the metallic state? I think more material characterization will be helpful, such as XRD.
4. The author compared the performance of Ru/Al2O3 and Ru/SiO2 catalysts for ammonia decomposition. What about the performance compared to other ways to produce hydrogen, for example water electrolysis? Is this method energy efficient compared to other methods? Can you talk about the advantages of this method compared to others? Otherwise, it's hard to tell the significance of the work.
Author Response
We appreciate the reviewer's kind and valuable comments. Please see the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The author has addressed the concerns and questions in detail and revised the manuscript accordingly. I recommend for publication.
