Effects of Alkali Metals on Nickel/Alumina Catalyzed Ethanol Dry Reforming
, Young Jin Kim, Ji Hoon Park, Iljeong Heo, Tae Sun Chang * and Jin Hee Lee *Round 1
Reviewer 1 Report
An interesting and complete study about ethanol dry reforming over Ni/Al2O3 catalysts promoted by alkali is presented. The catalysts are characterized in initial and used states by different techniques in order to study correlations with activity results, paying attention to deactivation by coke deposition, most relevant for practical application.
Authors should pay attention to the following issues in a revised version.
An important concern in this work is that basic characterization of the active nickel is practically missing. Since activity details are expected to depend on this aspect, authors are asked to make an effort to provide any characterization of the nickel dispersion in the activated (reduced) systems. I.e. are there any differences in the catalysts concerning nickel particle size? Probably TEM (employed for post-reaction characterization) - as well as XPS or any chemically based adsorption method - could provide hints in such sense given the relatively high nickel loading of the catalysts.
A second concern is that no information on product distribution nor adequate description and discussion, as done for the Ni/Al2O3 system, of their possible role on coke formation, etc. is provided for the alkali promoted catalysts.
Other minor comments are as follows.
In Fig. 4, labels for the phases observed are small and difficult to see. The same occurs for the scale in TEM images (Fig. 6).
In page 8/15 Fig. 5 instead of Fig. 8.
Author Response
Please see the attachment
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper deals with the ethanol dry reforming on Ni-based catalysts. The manuscript is well organized and reports interesting information on the subject. In my opinion some aspects should be clarified and/or implemented.
In particular, the authors should take into consideration the following points: -The English form should be revised in all the manuscript.
-In the introduction the author should discussed also to one of the main drawbacks of the Ni-based catalysts as the toxicity of this metal and of his oxides.
-Line 57: “reported the coke” should be "reported that"…
-Line 65: “base sites” should be "basic sites". Check in all the manuscript.
-The authors should pay attention to the format required by the Catalysts journal. The experimental parts should be put at the end of the manuscript, before the references.
-There are some references to validate the formula (3) line 107? Moreover, it is not clear how the authors determined the amounts of carbon deposition, the TGA was connected to a mass spectrometer?
Finally, all the formulas in the manuscript present a different character respect to the manuscript format.
-Scheme 1 present a different format respect to all the manuscript.
-It could be interesting evaluated the catalytic activity varying the temperature on the Ni-modified catalysts. The present of the alkali metals could decrease the temperature of the maximum CO2 and ethanol conversion.
-In the figure 6 should be transferred the images of the fresh catalysts (maybe as another figure) to better compare the morphology. However, comparing the fig. S5 and the fig.6 it is very difficult distinguish the formation of coke. The authors should perform an EDX analysis to better highlighted where is the coke.
Line 243: “The amorphous carbon and nanotube shaped carbon were mainly observed” also in the fig. S5 seem to be these species (as black points). Please explain better where and how it is possible to affirm that the coke is present only in the spent samples with these TEM images.
Due to the importance of the basic sites formed by the introduction of the alkali metals, the authors should perform the FTIR characterization before and after the catalytic tests to evaluate the formation of particular bonds or of different types of carbonates species.
Author Response
Please see the attachment
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments adequately addressed.
Reviewer 2 Report
The authors have satisfactory improved the manuscript.
