Impact of Geometric and Electronic Factors on Selective Hydro-Deoxygenation of Guaiacol by Surface-Rich Metal/Silica Catalysts
Round 1
Reviewer 1 Report
This paper describes complex processes of hydrogenation and deoxygenation of guaiacol under catalytic action of various metals (Mo, W, Re, Fe, etc.) on silica Aerosil380. Guaiacol is a lignan it was chosen as a model molecule, which can be obtained from native lignin. The basement of this study was the production of hydrocarbons from oxygenated biomolecules such as lignans. This is an actual goal for chemical science and industry.
The authors describe thoroughly characterization of catalysts. Transformation of guaiacol was studied with different catalysts. To estimate the hydro-deoxygenation processes, the author used pseudo van Krevelen diagram. Plausible reaction mechanisms are discussed.
This is a very good paper from catalyst point of view.
However, there are some weak points, that must be improved.
1. Please, add in Abstract the main reaction products that were obtained from guaiacol (data from Figure A4).
2. In experimental part in the section “Catalyst preparation”, add definite metal salts that were used in the synthesis of catalysts. Otherwise, this work is hardly reproducible.
After these minor revisions, the paper may be accepted.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This manuscript prepared different d-metals (Mo, W, Re, Fe, Co, Ni, Cu, Pd, Ag) supported on SiO2 and used as the catalysts for evaluate their performance in hydrodeoxygenation of lignin derived guaiacol. The authors characterized the structure, textural, reducible and acid properties of the catalysts by using different technologies, and also compared the catalytic performance based on catalysts, reaction temperature and time. The products distribution in view of H/C and O/C ratios was also studied based on catalysts and processing factors. However, by these superficial experiments, analysis and discussion, it is hard to gain valuable insights into the authors claimed “Geometric and Electronic” factors in guaiacol HDO reaction, because guaiacol HDO is a very complex and the products are depended on the synergistic effect between metal and acid in catalysts. The only atom distance and d-band center of metals are no enough to depict catalytic performance, considering the complicated local structure of the crystal metal surface in a HDO process at high temperatures. The authors should focus on some metals and deeply analyze the catalytic performance based on the role of metal and acid and how the cooperative effect of metal and acid affect the HDO process and the product selectivity by supplying essential experiments, analysis and discussion.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The work was well designed and the manuscript was well written. The following need to be addressed.
(1) The powder X-Ray diffraction patterns of the silica after metal loading should be included.
(2) The citation should be written in the end of the sentence (before full stop).
(3) We may need only one of the SEM images of Fig. 3, either magnification 10000x and 20000x (because it is close each other)
Author Response
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Author Response File: Author Response.pdf
