Dimethyl Ether Oxidation over Copper Ferrite Catalysts
Round 1
Reviewer 1 Report
Catalytic combustion is generally known as one of the most efficient and promising technologies for the abatement of volatile organic compounds (VOCs) and deep oxidation of different fuels and exhaust emissions. Typical combustion catalysts involve noble metals. However, the use of noble metals suffers from high cost, tendency to poisoning and low thermal stability. In recent years, transition metal oxides, especially binary oxides with bifunctional properties, have become suitable alternatives as catalysts for deep oxidation applications. In the present work, copper ferrite catalysts have been synthesized and have been evaluated in the gas-phase oxidation of DME. In this investigation, the catalysts were well characterized, and the catalytic performances were well evaluated. Additionally, some explanations for the results were proposed. The conclusions were soundly supported by the data. This investigation is significant for developing catalysts used in the deep oxidation of different fuels and exhaust emissions. In my opinion, this manuscript could be accepted for publication.
Author Response
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Reviewer 2 Report
In this paper, the authors apply the experimental method to study catalytic performances of the FexCu1-x mixed oxide catalysts. The authors have found that the Fe0.67Cu0.33 catalyst exhibits the highest catalytic activity in DEM oxidation. These results are very interesting. It is acceptable for publication in this journal after revision.
1).The description of abstract should be well summarized. The authors should be given the specific data for clear read.
2).What the evidence of the choose of FexCu1-x. the authors stated the Fe0.67Cu0.33 shows highest catalytic activity, why?
3).In introduction, the research background of the energy and catalytic materials should be well summarized. For these energy and catalytic materials, the authors should be cited these references: Appl Surf Sci. 2022;591:153168. Int J Hydrogen Energ. 2021;46:35342-35350. Mat Sci Eng B. 2022;281:115746. Int J Energ Res. 2020;44:4997-5007. Int J Energ Res. 2021;45:15512-15520. J Electron Mater. 2020;49:7363-7369.
4).The authors not only compared the catalytic performances of FexCu1-x compound but also compared to the catalytic performance with the other catalytic materials.
5).Why not provide the XED and SEM for observing the microstructure? In fact, the microstructure and catalytic properties of FexCu1-x is influenced the phase or concentrations.
6).In Table 1, the authors only consider the three concentration for x=0.33, 0.5 and 0.67. I think that three concentration is difficult to reflect the change of catalytic performances.
7).How to consider the influence of oxygen concentration on the catalytic properties of this compound?
Author Response
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Reviewer 3 Report
Review (major revision):
The article “Dimethyl Ether Oxidation Over Copper Ferrite Catalysts” by Smyrnioti, and Ioannides, discusses the oxidation of DME over different spinel type catalysts. They utilized a Cu and Fe type catalyst, where they altered the ratio of the metals.
Introduction:
The introduction part describes the topics of the manuscript well. Significant improvements in English are necessary.
Results and discussion
- In Figure 1 a) the units on the vertical axis should be removed, since the curves were offset. The numbers are therefore arbitrary.
- The sample Fe67Cu0.33 contains the smallest amount of CuO, and its crystallites are the largest among the spinel catalysts. How can than the first peak in the TPR profile be the highest among the samples?
- In line 274, the authors should define the “best” redox properties more. Is it defined by the lowest temperature of reduction, or is it defined as the highest reduction extent.
- If highly dispersed copper species are the underlying reason for increased catalytic activity, would 2 nm CuO particles dispersed over high surface area CeO2 work even better?
- What was the experimental error when the catalytic tests were repeated?
- What is the long term stability of the synthesized materials?
Materials and Methods
The materials and methods part is well written.
Conclusion:
Some minor English improvements are needed. Other than that, the conclusion part is written well.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
The experiments were performed in a well-organized way. The catalyst characterization results and the conclusion from these results explain well the catalyst activity results. This paper can be accepted in its present form with minor revision.
- Gas-phase oxidation of DME is possible at high temperatures. Hence for the catalyst activity test please provide the DME oxidation over quartz (similar bead height) and an empty reactor.
- Also, provide a table with conversion and activity based on previous works with different oxide catalysts (including Fe and Cu oxides), used for the DME oxidation reaction.
Author Response
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Round 2
Reviewer 3 Report
The authors sufficiently alleviated all of my reservations. I believe the manuscript is acceptable in its current form. I congratulate the authors
for all the hard work.
