Hydrogen Production via Methanol Steam Reforming over CuO/ZnO/Al2O3 Catalysts Prepared via Oxalate-Precursor Synthesis
Round 1
Reviewer 1 Report
Hydrogen production by methanol steam reforming over CuO/ZnO/Al2O3 catalysts based on oxalate-precursor synthesis. Following revisions should be made before publication:
1. The abstract should be made more concise, highlighting the novelty and major finding. More quantitative information should be presented than qualitative.
2. The rational design of the transition metal based materials can be explained in the introduction section with the reference of following articles:
doi.org/10.1016/j.cej.2021.132345, and doi.org/10.1016/j.est.2023.108220
3. JCPDS card should be updated to the XRD patterns and peak should be indexed with plane.
4. The sample name should be uniform throughout the manuscript.
5. High resolution FESEM and mapping is necessary.
6. Some grammatical errors can be checked and corrected.
1. Some grammatical errors can be checked and corrected.
Author Response
Catalysts
ID: 2620234
Title: Hydrogen production by methanol steam reforming over CuO/ZnO/Al2O3 catalysts prepared via oxalate-precursor synthesis
Authors: Haiguang Wang, Yongfeng Liu* and Jun Zhang
Dear Editor and Reviewers,
We would like to thank you for allowing us to submit a revised manuscript. Thanks very much for taking your time to review this manuscript. We really appreciate all your comments and suggestions! Based on the instructions provided in your letters, we uploaded the original manuscript with all the changes in a different color (blue). We sincerely hope that the revised manuscript is accepted for publication in Catalysts.
The point by point responses based on reviewer's comments and the corresponding modifications are listed below.
Hydrogen production by methanol steam reforming over CuO/ZnO/Al2O3 catalysts based on oxalate-precursor synthesis. Following revisions should be made before publication:
- The abstract should be made more concise, highlighting the novelty and major finding. More quantitative information should be presented than qualitative.
Re: First, thank you very much for the detailed and patient revisions. We have rewritten the abstract to make it more concise and highlight the novelty and scientific findings. More quantitative information was provided.
- The rational design of the transition metal based materials can be explained in the introduction section with the reference of following articles:
doi.org/10.1016/j.cej.2021.132345, and doi.org/10.1016/j.est.2023.108220
Re: We elaborated on the rational design of transition metal based materials in the introduction by citing these two closely related literatures.
- JCPDS card should be updated to the XRD patterns and peak should be indexed with plane.
Re: We have marked the JCPDS card No. of the phase in the manuscript in detail.
- The sample name should be uniform throughout the manuscript.
Re: We have inspected and unified the names of the samples in the manuscript.
- High resolution FESEM and mapping is necessary.
Re: Because the grain sizes of the prepared sample are small, the mapping can't be obtained well. Meanwhile, the conductivity of the sample is poor, making it difficult to obtain particularly clear images. We will carefully adopt the reviewer’s suggestions in our subsequent research work, improve the quality of the images, and carefully study the relevant characterization results.
- Some grammatical errors can be checked and corrected.
Re: We have checked and corrected some grammar errors.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors presented new important data on methanol steam reforming over CuO/ZnO/Al2O3 catalysts. Before the manuscript can be accepted for publication, some corrections, listed below, have to be made:
Within the article: the authors use many times the expressions about “synergy”, for example “strong synergy between CuO and ZnO”. What do the authors mean by “synergy”? Please add some text somewhere in the article explaining what exactly is meant by “synergy”?
Title:
1. “prepared via” instead of “based on”
Abstract:
1. “catalysts are commonly used catalysts” instead of “catalyst is a commonly used catalyst”
2. “for the methanol” instead of “for rea methanol”
3. “catalysts by co-precipitation” instead of “catalyst by co-precipitation”
4. space time yield” instead of “STY”
Introduction:
1. What do the authors mean by “the most in-depth method”? Please re-wright more clearly!
2. “MSR produces” instead of “MSR produce”
3. components were well-distributed” instead of “components was well-distributed”
4. “200 W” instead of “200W”
5. “hydrotalcite” instead of “hydrotalcite-like”
Experimental:
1. “as XYC (X is W for water, or E for ethanol; Y is W for water bath, or M for microwave irradiation)” instead of “as XYC”
2. “summary of the preparation” instead of “summary the preparation”
3. “in helium” instead of “in a Helium”
4. “were compressed into the pellets” instead of “were compressed into a pellet”
5. “at a pressure lower” instead of “at lower”
Results and discussion:
1. “deviated from original positions” instead of “deviated original position”
2. “Grain size values and” instead of “Results of grain size and” in Table 2
3. “larger surface area and bigger pore volume” instead of “bigger surface area and pore volume”
4. “in precursors prepared under” instead of “in precursor prepared under”
5. “the catalysts possessed” instead of “the catalyst possessed”
6. “high temperature reduction peak emerged” instead of “high emerged”
7. “two are low temperature” instead of “two were divided to low temperature”
8. “third is high” instead of “third was divided to high”
9. “-1” must be superscript in “1.0 h-1” in Table 4
Conclusion:
1. “precursor mainly contains … exhibits” instead of “precursor mainly contain … exhibit”
2. “STY of H2” instead of “STYH2”
References:
1. First reference has no number! Please correct!
Minor editing of English language required
Author Response
Catalysts
ID: 2620234
Title: Hydrogen production by methanol steam reforming over CuO/ZnO/Al2O3 catalysts prepared via oxalate-precursor synthesis
Authors: Haiguang Wang, Yongfeng Liu* and Jun Zhang
Dear Editor and Reviewer,
We would like to thank you for allowing us to submit a revised manuscript. Thanks very much for taking your time to review this manuscript. We really appreciate all your comments and suggestions! Based on the instructions provided in your letters, we uploaded the original manuscript with all the changes in a different color (blue). We sincerely hope that the revised manuscript is accepted for publication in Catalysts.
The point by point responses based on reviewer's comments and the corresponding modifications are listed below.
The authors presented new important data on methanol steam reforming over CuO/ZnO/Al2O3 catalysts. Before the manuscript can be accepted for publication, some corrections, listed below, have to be made:
Within the article: the authors use many times the expressions about “synergy”, for example “strong synergy between CuO and ZnO”. What do the authors mean by “synergy”? Please add some text somewhere in the article explaining what exactly is meant by “synergy”?
Re: First, thank you very much for the detailed and patient revisions. Here, the “synergy” we mentioned means synergistic effect or synergism, which means that CuO and ZnO coordinate and interact closely with each other in the catalysts. During the catalyst preparation process, microwave irradiation promotes the substitution of Zn2+ in ZnC2O4·xH2O compound by Cu2+ and increases the content of (Cu,Zn)C2O4 phase in precursors. In this way, Cu and Zn atoms are in close contact, dispersed and perfectly connected, which accordingly enhances the synergistic effect between Cu and Zn atoms in Cu/ZnO/Al2O3 catalysts. We have made relevant discussions in appropriate places in the manuscript.
Title:
- “prepared via” instead of “based on”
Re: We have made corresponding modifications.
Abstract:
- “catalysts are commonly used catalysts” instead of “catalyst is a commonly used catalyst”
Re: We have made corresponding modifications.
- “for the methanol” instead of “for rea methanol”
Re: We have made corresponding modifications.
- “catalysts by co-precipitation” instead of “catalyst by co-precipitation”
Re: We have made corresponding modifications.
- space time yield” instead of “STY”
Re: We have made corresponding modifications.
Introduction:
- What do the authors mean by “the most in-depth method”? Please re-wright more clearly!
Re: We rewrite the sentence, as follows, "MSR is the most widely and deeply studied method."
- “MSR produces” instead of “MSR produce”
Re: We have made corresponding modifications.
- components were well-distributed” instead of “components was well-distributed”
Re: We have made corresponding modifications.
- “200 W” instead of “200W”
Re: We have made corresponding modifications.
- “hydrotalcite” instead of “hydrotalcite-like”
Re: We have made corresponding modifications.
Experimental:
- “as XYC (X is W for water, or E for ethanol; Y is W for water bath, or M for microwave irradiation)” instead of “as XYC”
Re: We have made corresponding modifications. And we have made relevant supplements, as follows, P is for precursor; C is for calcined catalyst.
- “summary of the preparation” instead of “summary the preparation”
Re: We have made corresponding modifications.
- “in helium” instead of “in a Helium”
Re: We have made corresponding modifications.
- “were compressed into the pellets” instead of “were compressed into a pellet”
Re: We have made corresponding modifications.
- “at a pressure lower” instead of “at lower”
Re: We have made corresponding modifications.
Results and discussion:
- “deviated from original positions” instead of “deviated original position”
Re: We have made corresponding modifications.
- “Grain size values and” instead of “Results of grain size and” in Table 2
Re: We have made corresponding modifications.
- “larger surface area and bigger pore volume” instead of “bigger surface area and pore volume”
Re: We have made corresponding modifications.
- “in precursors prepared under” instead of “in precursor prepared under”
Re: We have made corresponding modifications.
- “the catalysts possessed” instead of “the catalyst possessed”
Re: We have made corresponding modifications.
- “high temperature reduction peak emerged” instead of “high emerged”
Re: We have made corresponding modifications.
- “two are low temperature” instead of “two were divided to low temperature”
Re: We have made corresponding modifications.
- “third is high” instead of “third was divided to high”
Re: We have made corresponding modifications.
- “-1” must be superscript in “1.0 h-1” in Table 4
Re: We have made corresponding modifications.
Conclusion:
- “precursor mainly contains … exhibits” instead of “precursor mainly contain … exhibit”
Re: We have made corresponding modifications.
- “STY of H2” instead of “STYH2”
Re: We have made corresponding modifications.
References:
- First reference has no number! Please correct!
Re: We have made corresponding modifications.
Comments on the Quality of English Language
Minor editing of English language required
Re: We have checked and corrected some grammar errors.
Author Response File: Author Response.docx
Reviewer 3 Report
The paper may be of interest to the community of materials scientists looking for ways to produce hydrogen more efficiently. Methanol steam reforming is one of four catalytic processes used to produce hydrogen (with the release of carbon dioxide). Transition metal based compounds, such as zinc chromite, serve as classical catalysts for both the synthesis and decomposition of methanol. This paper attempts to clarify the relationships between the activity of the CZA catalyst and its composition, synthesis routes, and microstructure. In this context, the manuscript could be considered worthy of publication. However, some improvements could be made. There are two main aspects that the authors might consider:
1) The writing of the manuscript needs further revision. The title is not clear. The conclusion section is limited and incomplete; it is not clear what new information, scientific knowledge, innovations in materials or methodology were obtained in the work. A more expanded version of the conclusion could enhance the manuscript.
2) From a technological perspective, the paper is much more technical than scientific. This means that the clarity of subsections regarding the discussion of the catalytic activity and efficiency of CZA-based systems in hydrogen production by controlled methanol decomposition needs some improvement. For example, the so-called "synergy effect between CuO and ZnO" could be explained in more detail. The chemistry of the active sites, the reaction route of methanol decomposition, and the structural sensitivity of the reaction could be discussed in more details.
Author Response
Catalysts
ID: 2620234
Title: Hydrogen production by methanol steam reforming over CuO/ZnO/Al2O3 catalysts prepared via oxalate-precursor synthesis
Authors: Haiguang Wang, Yongfeng Liu* and Jun Zhang
Dear Editor and Reviewer,
We would like to thank you for allowing us to submit a revised manuscript. Thanks very much for taking your time to review this manuscript. We really appreciate all your comments and suggestions! Based on the instructions provided in your letters, we uploaded the original manuscript with all the changes in a different color (blue). We sincerely hope that the revised manuscript is accepted for publication in Catalysts.
The point by point responses based on reviewer's comments and the corresponding modifications are listed below.
The paper may be of interest to the community of materials scientists looking for ways to produce hydrogen more efficiently. Methanol steam reforming is one of four catalytic processes used to produce hydrogen (with the release of carbon dioxide). Transition metal based compounds, such as zinc chromite, serve as classical catalysts for both the synthesis and decomposition of methanol. This paper attempts to clarify the relationships between the activity of the CZA catalyst and its composition, synthesis routes, and microstructure. In this context, the manuscript could be considered worthy of publication. However, some improvements could be made. There are two main aspects that the authors might consider:
1) The writing of the manuscript needs further revision. The title is not clear. The conclusion section is limited and incomplete; it is not clear what new information, scientific knowledge, innovations in materials or methodology were obtained in the work. A more expanded version of the conclusion could enhance the manuscript.
Re: First, thank you very much for the detailed and patient revisions. We have made modifications to the sentences and grammar of the manuscript, and made modifications to the title. We have rewritten the conclusion section, which was modified and expanded; The new catalysts used in this study, the new preparation methods used, and the new scientific understanding obtained were elaborated in detail.
2) From a technological perspective, the paper is much more technical than scientific. This means that the clarity of subsections regarding the discussion of the catalytic activity and efficiency of CZA-based systems in hydrogen production by controlled methanol decomposition needs some improvement. For example, the so-called "synergy effect between CuO and ZnO" could be explained in more detail. The chemistry of the active sites, the reaction route of methanol decomposition, and the structural sensitivity of the reaction could be discussed in more details.
Re: We have further elaborated on the structure-activity relationship between the microstructure of the catalysts and the MSR catalytic performance, and provided a more detailed explanation of the “synergy between CuO and ZnO”. Here, the “synergy” we mentioned means synergistic effect or synergism, which means that CuO and ZnO coordinate and interact closely with each other in the catalysts. During the catalyst preparation process, microwave irradiation promotes the substitution of Zn2+ in ZnC2O4·xH2O compound by Cu2+ and increases the content of (Cu,Zn)C2O4 phase in precursors. In this way, Cu and Zn atoms are in close contact, dispersed and perfectly connected, which accordingly enhances the synergistic effect between Cu and Zn atoms in Cu/ZnO/Al2O3 catalysts. We have made relevant discussions in appropriate places in the manuscript.
Besides, we have also discussed in detail the chemical properties of the catalyst's active sites, the reaction routes for methanol decomposition, and the structural sensitivity of MSR. In the aging process of catalyst precipitation mother liquor, microwave irradiation can promote the generation of (Cu,Zn)C2O4 phase, and the synergistic effect between CuO-ZnO after the phase roasting is stronger, CuO and ZnO grains are smaller, the surface Cu content is higher, so the active sites are more uniform. The chemical environment and energy state of Cu and Zn components in the catalyst have changed. As the electronegativity of Zn is higher than that of Cu, the outermost electrons of Cu shift to Zn, thus reducing the electron cloud density of Cu and increasing the electron binding energy, while the electron cloud density of Zn increases and decreasing the electron binding energy. All these indicate that the synergistic effect of CuO-ZnO in EMC is the strongest, which has the most active sites. Thus, the activity of EMC for MSR is improved.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Accept
