Process Development for Methyl Isobutyl Ketone Production Using the Low-Pressure One-Step Gas-Phase Selective Hydrogenation of Acetone
Round 1
Reviewer 1 Report
The work studied the process for the production of MIBK using a newly developed catalyst and its heat integration. The developed process has a return on investment of 29.6%. In the revision, the following question should be considered.
1. How the heat exchanger network is optimized? Why the energy of the stream corresponding to the condenser T103 is not recovered?
2. In Figure 7, why the curve corresponding to the raw material is significantly different from others? Especially the data corresponding to the third point.
3. In figure 9, there is some problem with the line number and the capital of the vertical axis. Please check and revise.
Author Response
We would like to take the opportunity to thank the reviewer for his valuable comments on this manuscript and for his insightful points to improve the manuscript. The manuscript has been revised as per the comments given by the reviewer, and our responses to each comment are shown below.
Comment #1: How the heat exchanger network is optimized? Why the energy of the stream corresponding to the condenser T103 is not recovered?
Response #1:
The authors would like to thank the reviewer for the comment. In the heat integration of the developed process, a preliminary heat exchanger network was first constructed, achieving the minimum heating and cooling targets. Usually, this is a restricted form that has a lot of heat exchanges, even uneconomically beneficial ones. Therefore, it is often beneficial to trade-off between the number of heat exchangers and the required energy by eliminating small heat exchangers that give little energy benefit in order to simplify the network, reduce capital costs, and improve the overall payback of the project. This technique is known as "network relaxation". With the assistance of Aspen Energy Analyzer v11, we were able to reach the heat exchanger network (relaxed form). For the condenser of T-103, in a restricted form of the heat integration, there are two cold streams that are technically feasible to exchange heat with the condenser of T-103, which are streams 2 and 5 (note that the inlet to Reb. 101 cannot be used since it is below the pinch while Cond. T-103 is above the pinch). However, these cold streams can’t cool the overhead of the Cond. T-101 (hot stream) to its liquid state, with their presence above the pinch point (Thot = 108.6 oC). Therefore, to implement the heat integration without crossing the pinch, the inlet to Cond. T-101 needs to be split into several streams, and only one of them is possible to be heat integrated. Usually, condensers and reboilers are uneconomically beneficial to be heat integrated with the process streams; therefore, in the revised manuscript we have only kept the process streams, which are shown in Figure 2.
Comment #2: In Figure 7, why the curve corresponding to the raw material is significantly different from others? Especially the data corresponding to the third point.
Response #2:
Thank you for your valuable insight. The relationship between the ROI and the raw material cost, like the rest of the variables, should be linear. The calculations were repeated, and the graph was corrected (see Figure 7).
Comment #3: In figure 9, there is some problem with the line number and the capital of the vertical axis. Please check and revise.
Response#3:
The comment has been considered. This has been corrected in the revised manuscript (please see Figure 9).
Reviewer 2 Report
The paper “Process Development for Methyl Isobutyl Ketone Production using Low-Pressure One-Step Gas-Phase Selective Hydrogenation of Acetone” can be accepted for publication, but several areas need improvement. I recommend this manuscript for publication after the clarification of the following major comments. See the comments below:
1. Define the novelty of this work.
2. Abstract: Need to revise. In the abstract, add a description to clarify the flow of work. Authors are advised to revise the abstract and please focus the abstract on your research approach.
3. Highlights/graphical abstracts are missing.
4. Some keywords should be revised in the manuscript.
5. The manuscript is in itself very hard to read. Several instances of repeated sentences have been used to describe the same thing. This has to be extensively taken care of throughout the manuscript.
6. The introduction section needs to be revised. Some more recent developments in this field are required to incorporate into the introduction section.
7. There are multiple grammatical errors in the manuscript. The manuscript could utilize some improvement in English by checking it with a native English speaker or software which provides their services for improving the quality of the manuscript.
8. The explanation of section 4. “Economic Analysis” is not sufficient and should be rewritten with a proper explanation.
9. It does not contain a deep enough analysis and discussion of section 4.2. “Sensitivity Analysis”. Need to be revised.
10. Future outlook in which you talk specifically about what is needed in terms of sustainable environment process development for Methyl Isobutyl Ketone Production be specific and avoid general vague phrases.
11. Authors should also write about the limitations of this technology.
12. Please mention a list of abbreviations.
13. The authors need to revise the conclusion section. It must clearly reflect the key conclusions and findings must be highlighted in points.
14. Add some recent references.
15. Paper requires thorough proofreading.
Author Response
We appreciate the reviewer for the insightful comments and the time and effort spent on reviewing the manuscript. The manuscript has been revised based on the comments given by the reviewer, and detailed point-by-point responses to all comments are given below.
Comment #1: “Define the novelty of this work.”
Response #1:
We appreciate very much the reviewer’s comments on the paper. The core part of any work is novelty. This study is a novel work and the first study on the process development of methyl isobutyl ketone (MIBK) production using low-pressure one-step gas-phase selective dehydrogenation of acetone based on a novel nano-Pd/nano-ZnCr2O4 catalyst. In order to clearly address the novelty of the current work, more details have been added in the abstract section (page 1, line 16) and in the introduction section (page 2, line 98).
Comment #2: “Abstract: Need to revise. In the abstract, add a description to clarify the flow of work. Authors are advised to revise the abstract and please focus the abstract on your research approach.”
Response #2:
We would like to thank the reviewer for the comment. We have revised the abstract section and have ensured that the flow of work is clearly defined. The abstract started with the importance of the product and then briefly addressed the main drawback of the conventional process. Then, we mentioned the area of the study with the aim of defining the novelty of the work. After that, we mentioned the approach, starting with the process flowsheet development to the heat integration and then to the economic evaluation of the process and the main findings obtained from the study (page 1, line 18).
Comment #3: “Highlights/graphical abstracts are missing.”
Response #3:
The graphical abstract has been added.
Comment #4: “Some keywords should be revised in the manuscript.”
Response #4:
The authors would like to thank the reviewer for his careful insight. We have eliminated some keywords to make the manuscript more specific: In addition, we have added the name of the catalyst to the keywords.
Comment #5: “The manuscript is in itself very hard to read. Several instances of repeated sentences have been used to describe the same thing. This has to be extensively taken care of throughout the manuscript.”
Response #5:
The comment has been considered. A thorough revision has been conducted to make the manuscript flow better.
Comment #6: “The introduction section needs to be revised. Some more recent developments in this field are required to incorporate into the introduction section.”
Response #6:
We are thankful for the suggestion. The introduction was revised and more recent development in the field has been added (e.g. please check page 2, line 72).
Comment #7: “There are multiple grammatical errors in the manuscript. The manuscript could utilize some improvement in English by checking it with a native English speaker or software which provides their services for improving the quality of the manuscript.”
Response #7:
Thanks for your comment. The manuscript was revised, and several errors have been corrected.
Comment #8: “The explanation of section 4. “Economic Analysis” is not sufficient and should be rewritten with a proper explanation.”
Response #8:
We highly appreciate your comment. More explanation has been added with a better representation of the economic variables with some equations describing the key economic indicators (economic analysis section, page 6, line 194). New sub-headlines have been added (e.g., 4.1. purchase cost, 4.2. raw material and utility costs, 4.3. total capital cost, and 4.4. total production cost).
Comment #9: “It does not contain a deep enough analysis and discussion of section 4.2. “Sensitivity Analysis”. Need to be revised.”
Response #9:
Thank you for your comment. This section considers only a brief economic sensitivity analysis; however, to enrich the content, more details and discussions have been added ( please see page 10, line 298).
Comment #10: Future outlook in which you talk specifically about what is needed in terms of sustainable environment process development for Methyl Isobutyl Ketone Production be specific and avoid general vague phrases.
Response #10:
We highly appreciate your suggestion. The process requires less pressure and, therefore, less electricity than the conventional process; this has a direct relationship with CO2 emissions that are associated with electricity production.
Comment #11: “Authors should also write about the limitations of this technology.”
Response #11:
The presented process is considered highly attractive since it eliminates the need for high-pressure (10-100) atm in the reaction section (this has already been addressed in the manuscript). However, although the catalyst is novel, it is still new (not yet mature) and its stability against impurities should be tested using a pilot plant.
Comment #12: “Please mention a list of abbreviations.”
Response #12:
Thank you for this comment. A list of abbreviations has been added at the end of the manuscript (see page 13).
Comment #13: “The authors need to revise the conclusion section. It must clearly reflect the key conclusions and findings must be highlighted in points.”
Response #13:
Thank you for your insightful comment. The authors have revised the conclusion section, and the main findings have been highlighted in points (page 12, line 382).
Comment #14: “Add some recent references.”
Response #14:
Thank you for this comment. More recent references have been added to the manuscript.
Comment #15: “Paper requires thorough proofreading.”
Response #15:
The comment has been considered. The authors have conducted thorough proofreading.
Round 2
Reviewer 1 Report
All comments are addressed in the revision. The manuscript can be accepted for publication.
Reviewer 2 Report
Recommendation: Accept
This paper will be useful to readers and researchers working in this area. I recommend publishing the manuscript in its present form.
Comments for author File: 
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