Numerical Simulation and Response Surface Analysis of Esterification of Monobutyl Chlorophosphate with n-Butanol in a Microchannel Reactor

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This research paper based on optimization of microreactor technology provides valuable insights that are relevant to the field. However the following correction must be done before it can be accepted for publication:

1. Try to improve the simplicity and readability of the sentences.

2. And 1-2 sentences to explicitly state the novelty of this research.

3. Add more recent to reflect the latest advances in the field. 

4. Include a table that summarizes recent literature and its findings.

5. Provide more details in the methods section. For example specify the experimental setup, measured parameters and statistical methods used for data analysis.

6. Support your methodology with references.

7. Improve the resolution and aspect ratios of the figures including Figure 1 and Figure 6. 

8. Include more recent references to support the results.

9. Ensure that the results are linked with research questions. 

10. Discuss the implications of these findings in the context of existing literature. 

11. Discuss the significance of this work and suggest areas for future research.

12. Show that the conclusions are directly related with the findings of this work. Do not introduce new ideas or information in the conclusions section.

Comments on the Quality of English Language

Try to improve the simplicity and readability of the sentences. For example:

• Current: "Majeda Khraisheh ... technologies as approaches to water production challenges."
• Improvement: "Majeda Khraisheh ... technologies addressing water production challenges."
• Current: "These technologies, which include freeze ... osmosis, humidification, and dehumidification desalination systems, offer a cost-effective and environmentally friendly method for treating large quantities of water production."
• Improvement: "Technologies such as freeze ... osmosis, and humidification and dehumidification desalination systems offer cost-effective and environmentally friendly methods for treating large volumes of water."
• Current: "The working principle of desiccant materials DMs relies on the adsorption phenomenon."
• Improvement: "The working principle of desiccant materials (DMs) relies on the phenomenon of adsorption."
• Current: "Due to ... (LDMs) may efficiently ... (Figure 1), and the humidity will decrease dramatically."
• Improvement: "Due to ... (LDMs) can efficiently ... (Figure 1), significantly reducing humidity."
• Current: "This review assesses the freshwater yield, GOR, and efficiencies of these integrated systems, as well as the innovation in the HDH desalination technology, particularly its incorporation with the MVC process."
• Improvement: "This review assesses the freshwater yield, Gain Output Ratio (GOR), and efficiencies of these integrated systems, with a focus on innovations in HDH desalination technology, particularly its integration with the MVC process."
• Current: "The membrane-based ... (MLDAD) process employs semi-permeable membranes to separate water vapor molecules from the air and absorb them."
• Improvement: "The membrane-based ... (MLDAD) process uses semi-permeable membranes to separate and absorb water vapor molecules from the air."

Author Response

Dear Reviewer,

 

We gratefully thank for your time spend making your constructive remarks and useful suggestions, which has significantly raised the quality of our manuscript and has enable us to improve the manuscript. According to your suggestions, we have made extensive revisions to our previous draft. The detailed point-by-point responses are listed below.

 

Reply to the comments on processes-3164131 “Numerical simulation and response surface analysis of esterification of monobutyl chlorophosphate with n-butanol in a microchannel reactor”.

 

Response

Comments 1:Try to improve the simplicity and readability of the sentences.

Response 1:

Thanks for your suggestion. We feel sorry for our poor writings, however, we do invite a native English speaker to help polish our article. And we hope the revised manuscript could be acceptable for you.

 

Comments 2: And 1-2 sentences to explicitly state the novelty of this research.

Response 2:

Thank you for your advice, we have added more information in the last of Introduction:

“In this paper, a numerical model for the esterification of monobutyl chlorophosphates with n-butanol in a straight-tube microchannel reactor was established using CFD. In addition, the response surface analysis method combined with numerical simulation was utilized to optimize the microchannel. Through numerical discussion and analysis, a prediction formula for the conversion of dibutyl chlorophosphate from monobutyl chlo-rophosphate reacting with n-butanol was proposed. This exploration is of significant pioneering and guiding value in the numerical simulation of the esterification of phospho-rus oxychloride in microchannels.” (Page 3)

 

Comments 3: Add more recent to reflect the latest advances in the field.

Response 3:

We sincerely appreciate your valuable comment. We have added more references (DOI-10.1016/J.CES.2023.118813; DOI-10.1016/J.CEJ.2023.143468; DOI-10.1016/J.CEJ.2022.140670) into the Introduction part in the revised manuscript. These literatures are all studies on strengthening reaction effects by using microchannel reactors, and the research methods are mainly experiment or CFD:

“Zhan et al.[1] proposed a highly selective oxidation method of glyoxal with nitric acid in a continuous flow microreactor. By precisely controlling the reaction temperature and residence time of the continuous flow microreactor system, the apparent rate constant, pre-exponential factor, and activation energy of glyoxal oxidation by nitric acid to glyoxylic acid were obtained. The glyoxylic acid reached 81.6%, while the selectivity was 92.4% with the set residence time of only 7.9 min at 68℃. Guo et al.[2] established a continuous flow system for oxylene nitration and determined the kinetics and mass transfer. Remarkably, the residence time of the microreactor system was reduced by an order of mag-nitude and the volume mass transfer coefficient improved by several orders of magnitude compared with the conventional stirred tank reactor. Moreover, the concentrated spent nitric acid was effectively recycled, further improving the sustainability and cost-effectiveness of the process. Chen et al.[3] proposed a novel ionic liquid (ILs)-catalyzed microreaction system. The reaction processes were optimized within microreactors of different inner diameters. The kinetics of the CO2 synthesis of carbonate catalyzed using ionic liquid (IL-[HMIM]Br) in a microreactor was evaluated, and the activation energy of [HMIM]Br was obtained. Based on numerical calculations of the mass transfer characteristics, the microreactor enhancement can reduce the reaction time to minutes; this is typically several hours in conventional reactors.” (Page 2)

Also, we added a Table below that summarizes the literatures which are mentioned in Introduction part.

 

Comments 4: Include a table that summarizes recent literature and its findings.

Response 4:

Thank you for your advice. The following table summarizes the references mentioned in the Introduction, but it was not included in the manuscript due to space constraints.

Table 1. Literature review in introduction

author	method	model	remark
Engler et al.[4]	Experiment and CFD	T-type micromixer	At low Reynolds number, the longer residence time enhances the fluid reaction performance of the microchannel, while at high Reynolds number, the secondary flow disturbance improves the mixing ability of the microchannel in a short time
Bawornruttanabooya et al.[5]	CFD and RSM method	split-and-recombine (SAR) microreactor	Methane conversion within the optimized microreactor was noted to be higher than that within the straight-channel microreactor due to the presence of secondary flow, especially at a higher Reynolds number, while CO/CO2 ratio was noted tobe slightly lower.
Wang et al.[6]	CFD	3D helical micromixer	The mixing efficiency of the 3D helical micromixer can reach 0.948, compared with the mixing efficiency of 0.78 in the traditional T-shaped (2D) plane channel. The result show that the three-dimensional helical structure can effectively improve the mixing efficiency.
Vega et al.[7]	Experiment	honeycomb microchannel reactor	The implementation of 3D honeycomb monolithic reactors, with a dihydroxybenzene selectivity above 99% at 80℃, for the sustainable production of hydroxylated aromatics.
Sohn et al.[8]	CFD	2D microchannel reactor	Invesitgating the conversion performance ofreverse water-shift reaction(RWGS) in catalyst-coated microchannel reactor whose inside surface is coated with Ni-catalyst by utilizing CFD simulations including chemical kinetics.
Zhan et al.[1]	Experiment and CFD	capillary microreactor	The method utilizes a microreactor to improve the reaction efficiency, selectivity and safety of the oxidation reaction between glyoxal and nitric acid. The apparent reaction rate constant, pre-exponential factor and activation energy of glyoxal to glyoxylic acid by nitric acid were obtained.
Guo et al.[2]	Experiment and CFD	heart-shaped microreactor	The residence time of the heart-shaped microreactor was reduced by an order of magnitude, while the volumetric mass transfer coefficient was improved by several orders of magnitude compared to conventional stirred tank reactors.
Chen et al.[3]	Experiment and CFD	microchannel reactor	The kinetics for carbonate synthesis with CO2 catalyzed by ionic liquid (IL-[HMIM]Br) in a microreactor was evaluated, and the activation energyof [HMIM]Br was obtained. This provides new opportunities for enhancing gas–liquid reactions with typical mass transfer control and for CO2 utilization.

 

Comments 5: Provide more details in the methods section. For example specify the experimental setup, measured parameters and statistical methods used for data analysis.

Response 5:

Thank you for your advice, we have added more information in section 2.1:

“The microchannel reactor model, based on the chemical reaction kinetics of esterification, was developed using the Fluent commercial CFD program. A species transport model, including volumetric chemical reactions, was used to consider various species properties and transport in the mixture. The chemical reaction rate in the microreactor was defined using the kinetics of monobutyl chlorophosphate with n-butanol, as suggested by Zhang et al.[9]. The reaction equationof n-butanol and MCP in the microchannel to produce DCP and its by-product,hydrogen chloride, is given in Figure 3.”(Page 4)

Also, the statistical method used in this study is mainly response surface analysis method (RSM), and the data processing method is described in detail in Section 4.4.

 

Comments 6: Support your methodology with references.

Response 6:

Thank you for your advice. We have improved it in the revised manuscript.

 

Comments 7: Improve the resolution and aspect ratios of the figures including Figure 1 and Figure 6.

Response 7:

Thank you for your advice, we have improved the resolution and aspect ratio of Figures 1 and 6 in the revised manuscript.

 

Comments 8: Include more recent references to support the results.

Response 8:

Thank you for your advice. We have added new information in Section 4:

“Chen et al.[10] also reported that the reactant conversion rate increases slowly with the increase in residence time and stabilizes at a fixed value.”(Page 8)

“This is attributed to the influence of the concentration gradient of reactants; moreover, it has been reported that the steric hindrance effect between reactant atoms can also lead to the same result[9].”(Page 10)

 

Comments 9: Ensure that the results are linked with research questions.

Response 9:

We have improved the content of the Results section and made sure that the results are closely linked with research question. The references we cite in the Results section are directly related to the esterification reaction we did and discuss their similar conclusions in detial.

 

Comments 10: Discuss the implications of these findings in the context of existing literature.

Response 10:

Thank you for your advice. Our findings are in common with many studies (Bawornruttanabooya et al.[5], 2017; Sohn et al.[8], 2020; Vega et al.[7], 2022; Chen et al.[10], 2022; Zhan et al.[1], 2023; Guo et al.[2], 2023; Chen et al.[3], 2023) aimed at optimizing the reaction system in terms of reactor structure, reactant concentration, fluid flow parameters, etc. However, due to the different reaction systems, it can only provide some regular conclusions for actual industrial production like the above studies, such as changing the reactor length and reactant concentration to increase the reactant conversion rate, changing the flow speed to increase the yield, etc. These contents are discussed in the Results section and further analyzed by response surface method in the manuscript. And we deeply hope our revised manuscript could be acceptable for you.

 

Comments 11: Discuss the significance of this work and suggest areas for future research.

Response 11:

Thank you for your advice. We have talked future research in the last of our revised manuscript.

“In addition to the esterification in this paper, future studies will focus on utilizing computational fluid dynamics (CFD) methods to simulate chemical reactions that may be extremely dangerous in actual industrial production, or reactions whose reactant material is rare. The method in this paper has positive significance for the realization of green, safe, and sustainable chemical industrial production.” (Page 17)

 

Comments 12: Show that the conclusions are directly related with the findings of this work. Do not introduce new ideas or information in the conclusions section.

Response 12:

Thank you for your advice. We have removed the original text “Future studies will focus on establishing a three-dimensional conjugate heat transfer model for microchannel esterification, and will explore the impacts of structural parame-ters, catalysts, operating conditions, and other factors using a new numerical model to better guide actual industrial production.” and suggested fields where this method could be applied in the future:

“In addition to the esterification in this paper, future studies will focus on utilizing computational fluid dynamics (CFD) methods to simulate chemical reactions that may be extremely dangerous in actual industrial production, or reactions whose reactant material is rare. The method in this paper has positive significance for the realization of green, safe, and sustainable chemical industrial production.” (Page 17)

 

The above content is all the changes we have made according to your comments. Thank you again for your positive comments and valuable suggestions to improve the quality of our manuscript, we hope the revised manuscript could be acceptable for you.

 

Yours sincerely,

Shang Gao on behalf of all the co-authors.

6 September 2024.

 

 

References in response

1. Wei, Z.; Junnan, W.; Chengxiang, H.; Bin, J.; Chunying, Z.; Youguang, M.; Taotao, F. Kinetics of glyoxal oxidation by nitric acid in a capillary microreactor. Chemical Engineering Science 2023, 276.
2. Shuai, G.; Le-wu, Z.; Bin-dong, L. Nitration of o-xylene in the microreactor: Reaction kinetics and process intensification. Chemical Engineering Journal 2023, 468.
3. Yu, C.; Jiayuan, Y.; Yiqian, Y.; Feng, H.; Chunshan, L. A continuous process for cyclic carbonate synthesis from CO2 catalyzed by the ionic liquid in a microreactor system: Reaction kinetics, mass transfer, and process optimization. Chemical Engineering Journal 2023, 455.
4. Engler, M.; Kockmann, N.; Kiefer, T.; Woias, P. Numerical and experimental investigations on liquid mixing in static micromixers. Chemical Engineering Journal 2003, 101, 315-322.
5. Bawornruttanaboonya, K.; Devahastin, S.; Mujumdar, A.S.; Laosiripojana, N. A computational fluid dynamic evaluation of a new microreactor design for catalytic partial oxidation of methane. International Journal of Heat and Mass Transfer 2017, 115, 174-185.
6. Junyao, W.; Xingyu, C.; Huan, L.; Yunpeng, L.; Tianhong, L.; Rui, W.; Bowen, C.; Weihua, Z. Efficient Mixing of Microfluidic Chip with a Three-Dimensional Spiral Structure. ACS omega 2022, 7, 1527-1536.
7. Gonzalo, V.; Asunción, Q.; Manuel, B.; A., C.J. Kinetic study of phenol hydroxylation by H2O2 in 3D Fe/SiC honeycomb monolithic reactors: Enabling the sustainable production of dihydroxybenzenes. Chemical Engineering Journal 2022, 428.
8. Sohn, S.; Yoon, S.H. Numerical study of heat and mass transfer by reverse water-gas shift reaction in catalyst-coated microchannel reactor. Journal of Mechanical Science and Technology 2020, 34, 2207-2216.
9. Zhang, Y.Q.; Li, J.; Jin, Y.; Chen, M.; Wang, Y.B. Determination of kinetic parameters of homogenous continuous flow esterification of monobutyl chlorophosphate in a microreactor. The Canadian Journal of ChemicalEngineering 2020, 98, 1139-1147.
10. Chen, Q.S.; Zheng, C.; Zhang, M.D. Numerical simulation of the esterification between chlorophosphate and n-butyl alcohol in microchannel reactor. Chemical Industry and Engineering Progress 2022, 41, 29-35, doi:10.16085/j.issn.1000-6613.2021-2526.

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I carefully read the paper of Gao et al. on the use of CFD and response surface analysis to analyse the esterification of monobutyl chlorophosphate with n-butanol in a microfluidic device. The author used response surface analysis in order to find the optimal process parameters. The paper requires major revisions before being published.

 

Comments:

- It is not clear the novelty of this paper compared to the current state of the art.

- Figure 3 and 5: It's not clear how these Figures can be useful in this format as almost no radial effect is present. If a radial effect is present, it would be better to have isoline instead.

- figure numbering is wrong; e.g., Figure 5 page 7 and page 9. Please review all the figure captions and references!

- page 9: "Figure 7 illustrates the spatial distribution of the MCP", "Figure 7(e) shows severe..", "These observations are confirmed 287 by the data presented in Figure 8"; "Further analysis in Figure 9 demonstrates that with a decrease in the 290 component mass ratio"; "As shown in Figure 9, the numerical calculation results indicate that the MCP trans-298 formation rate of the outlet position" wrong figure reference

- Can you explain better the results in "Figure 7. MCP conversion rate at the outlet of different inlet component ratios"?

- "Comparing the data in Figure 10..." wrong wrong figure reference

- Section 4.4: it is not clear whether the word "experiment"/"experimental" refers to physical experiments or numerical experiments. 

- page 12: "The intermediate point was repeated three times, resulting in a total of 15 numerical 341 experiments". Why a mechanistic simulation is repeated three times?

- Section 4.4: review all the captions, figure numbering and figure citations in the text

- Is the conversion rate the metric to be used to optimise the process? Most of the time, in continuous manufacturing you want to maximize the throughput or the productivity.

 

Comments on the Quality of English Language

Please review all the figure captions, numbers and how they have been referenced in the text.

Author Response

Dear Reviewer,

 

We gratefully thank for your time spend making your constructive remarks and useful suggestions, which has significantly raised the quality of our manuscript and has enable us to improve the manuscript. According to your suggestions, we have made extensive revisions to our previous draft. The detailed point-by-point responses are listed below.

 

Reply to the comments on processes-3164131 “Numerical simulation and response surface analysis of esterification of monobutyl chlorophosphate with n-butanol in a microchannel reactor”.

 

Response

Comments 1: It is not clear the novelty of this paper compared to the current state of the art.

Response 1:

Thank you for pointing this out. Organophosphates synthesized from phosphorus oxychloride are crucial industrial products with well-established production methods and industrial applications, including metal ion extraction, enhancement of polymer plasticity, pesticide production, and modification of surface activity. At present, most of the experimental studies are carried out in batch reactors, in the case of esterification reactions like these, achieving an ideal distribution of reactants in batch reactors is often challenging, leading to incomplete reactions. Therefore, the use of microchannel reactors with high specific surface areas can effectively address this issue. In this paper, a numerical model for the esterification of monobutyl chlorophosphates with n-butanol in a straight-tube microchannel reactor was established using CFD. In addition, the response surface analysis method combined with numerical simulation was utilized to optimize the microchannel. Through numerical discussion and analysis, a prediction formula for the conversion of dibutyl chlorophosphate from monobutyl chlorophosphate reacting with n-butanol was proposed. This exploration is of significant pioneering and guiding value in the numerical simulation of the esterification of phosphorus oxychloride in microchannels.

And we have added red sentences above in the last of Introduction part. (Page 3)

 

Comments 2: Figure 3 and 5: It's not clear how these Figures can be useful in this format as almost no radial effect is present. If a radial effect is present, it would be better to have isoline instead.

Response 2:

Thank you for pointing this out. Figure 3 illustrates the equation of the chemical reaction carried out in the microchannel reactor, which we presented in the second point of 2.2 Assumption. Figure 5 illustrates the change of mass fraction of the reactant MCP in the reactor along the flow direction under different length-diameter ratios. At present, we did not consider the change of the reactant in the radial direction, so we chose to use the mass fraction distribution contour of the reactant as shown in Figure 5 (now corrected to Figure 6) to characterize the reaction process.

 

Comments 3: figure numbering is wrong; e.g., Figure 5 page 7 and page 9. Please review all the figure captions and references!

Response 3:

We are very sorry for our incorrect writing, and we have made corrections according to your comments.

 

Comments 4: page 9: "Figure 7 illustrates the spatial distribution of the MCP", "Figure 7(e) shows severe..", "These observations are confirmed 287 by the data presented in Figure 8"; "Further analysis in Figure 9 demonstrates that with a decrease in the 290 component mass ratio"; "As shown in Figure 9, the numerical calculation results indicate that the MCP trans-298 formation rate of the outlet position" wrong figure reference

Response 4:

It is really a giant mistake to the whole quality of our article. We feel really sorry for our carelessness. We have corrected it and we also feel great thanks for your point out.

 

Comments 5: Can you explain better the results in "Figure 7. MCP conversion rate at the outlet of different inlet component ratios"?

Response 5:

Thank you for your advice. We have re-written this part in the revised manuscript, and added new discussion with other’s study to better describe the effect of change of mass fraction ratio of the esterification reaction:

“Figure 8 illustrates the spatial distribution of the MCP mass fraction under different inlet component mass ratios in the microchannel. As the mass ratio of the components decreases, the esterification reaction intensifies at the inlet. Figure 8(e) shows severe consumption of MCP at the microchannel inlet (x/L < 0.1). These observations are confirmed by the data presented in Figure 9. At x/L = 0.2, the MCP conversion rate under the conditions of low component ratio was significantly higher compared to that under high component ratio conditions. Further analysis in Figure 10 demonstrates that with a decrease in the component mass ratio, the MCP conversion rate in the microchannel reactor gradually increases along the flow direction. However, the increase in the MCP conversion rate is more pronounced in the first half of the microchannel, with a slower rate of increase in the second half. This is attributed to the influence of the concentration gradient of reactants; moreover, it has been reported that the steric hindrance effect between reactant atoms can also lead to the same result[1]. In the first half of the microchannel, where the reactant concentration is high, the esterification reaction is more intense. However, in the second half, the conversion of reactant MCP gradually diminishes due to the progress of the chemical reaction and molecular diffusion. As shown in Figure 10, the numerical calculation results indicate that the MCP transformation rate of the outlet position is 72.17% with a n-butanol/MCP mass ratio of 10:5 of the inlet component, which is significantly higher than that with a 10:1 component ratio.” (Page 10)

 

Comments 6: "Comparing the data in Figure 10..." wrong wrong figure reference

Response 6:

We are very sorry for our wrong figure reference, and we have made corrections according to your comments.

 

Comments 7: Section 4.4: it is not clear whether the word “experiment”/“experimental” refers to physical experiments or numerical experiments.

Response 7:

We sincerely thank you for careful reading. “Experimental” here refers to numerical experiments, and we have changed “experimental” into “numerical experiments” in the manuscript. Thank you again for your careful check. (Page 12)

 

Comments 8: page 12: "The intermediate point was repeated three times, resulting in a total of 15 numerical experiments". Why a mechanistic simulation is repeated three times?

Response 8:

Thank you for pointing this out. The test design of three-factor response surface is usually designed to explore the influence of the three factors on the response variable and the interaction between the factors. In the design, it is usually necessary to select a representative level in order to better study the change trend and influencing factors of the response variables, and the design of three-factor and one-level usually requires 15 groups of tests. The central point replication test needs to be repeated 3 times to better examine the fit of the central region.

 

Comments 9: Section 4.4: review all the captions, figure numbering and figure citations in the text

Response 9:

We sincerely thank you again for careful check, we feel sorry for our carelessness. In our resubmitted manuscript, the figure numbers and figure citations have been revised. Thanks for your correction!

 

Comments 10: Is the conversion rate the metric to be used to optimise the process? Most of the time, in continuous manufacturing you want to maximize the throughput or the productivity.

Response 10:

Thank you for your question. Yes, the conversion rate is an important indicator we use to evaluate the effectiveness of the reaction. A reaction with a high conversion rate usually means a higher product yield and lower by-product generation. By optimizing the reaction conditions, the conversion rate of the reaction can be increased, and the purity and yield of the product can be improved.

 

The above content is all the changes we have made according to your comments. Thank you again for your positive comments and valuable suggestions to improve the quality of our manuscript, we hope the revised manuscript could be acceptable for you.

 

Yours sincerely,

Shang Gao on behalf of all the co-authors.

6 September 2024.

 

 

References in response

1. Zhang, Y.Q.; Li, J.; Jin, Y.; Chen, M.; Wang, Y.B. Determination of kinetic parameters of homogenous continuous flow esterification of monobutyl chlorophosphate in a microreactor. The Canadian Journal of Chemical Engineering 2020, 98, 1139-1147.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Good Day,

The manuscript describes results obtained in a field of great interest nowadays. The numerical simulations are important also for industrial applications (for instance for the synthesis installation, for the reactors and so on). The manuscript is in general well written and well documented. The English language is fine trough the whole manuscript.

The Introduction could be improved by citing more articles and adding more information. The main topic is related to esterification, but the transesterification, an important option to conduct esterification process, is not mentioned at all.  And also the polymers phosphorus containing, which could be synthesized by different modified esterification processes. For instance, the review of Ilia et al. published in Advances in Polymer Technology, Vol. 33, No. S1, 2014, DOI 10.1002/adv.21437 should be cited, in order to show the importance of transesterification method, as well the possibility to obtain different polyesters phosphorus containing. In the mentioned review the method is similar to your method, while a glycol is used, instead of butanol, and dialkyl H phosphate instead of monobutyl chlorophosphate. Moreover, also aryl phosphorodichloridates were employed to obtain polymers, as in your work you also referred to chlorinated derivatives (i.e. phosphorus oxychloride, trichloride, chlorophosphate and so on).

In the last decades, a variety of different polyphosphonates and polyphosphate esters have been produced via transesterification. This method, due to its huge importance in the field, should be mentioned at the Introduction.

The results and discussion and well described, the calculation procedures are presented in details. The conclusions are sustained by the presented results and the numerical simulations were conducted to study the performance of a microchannel reactor with an adjustable tube length. The reaction kinetics constants necessary for the simulations were determined based on previous experimental data.

After performing the minor revision in agreement with the above mentioned suggestions and recommentdations, the manuscript could be considered for publication.

Best regards!

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

 

We gratefully Thank you for your nice comments on our article. According to your suggestion, we have made revisions to our previous draft. The detailed responses are listed below.

 

Reply to the comments on processes-3164131 “Numerical simulation and response surface analysis of esterification of monobutyl chlorophosphate with n-butanol in a microchannel reactor”.

 

 

Response

Comments 1: “The Introduction could be improved by citing more articles and adding more information. The main topic is related to esterification, but the transesterification, an important option to conduct esterification process, is not mentioned at all. And also the polymers phosphorus containing, which could be synthesized by different modified esterification processes. For instance, the review of Ilia et al. published in Advances in Polymer Technology, Vol. 33, No. S1, 2014, DOI 10.1002/adv.21437 should be cited, in order to show the importance of transesterification method, as well the possibility to obtain different polyesters phosphorus containing”.

Response 1:

We sincerely appreciate your valuable comments. We have checked the literature (DOI 10.1002/adv.21437) carefully and added it into the Introduction part in the revised manuscript.

“Transesterification is one of the most common reactions in the field of organic chemistry. Due to its mild reaction conditions, high product diversity, and wide industrial application, it has become an important technology in chemical production. Ilia et al.[1] carefully reviewed the preparation of polymeric phosphonic acid esters via four important methods: polycondensation, polyaddition, transesterification, and the ROPs of cyclic phosphites through enzymes or other catalysts.” (Page 3)

 

Thank you again for your positive comments and valuable suggestions to improve the quality of our manuscript. And we hope the revised manuscript could be acceptable for you.

 

Yours sincerely,

Shang Gao on behalf of all the co-authors.

6 September 2024.

 

 

References in response

1. Ilia, G.; Simulescu, V.; Mak, C.A.; Crasmareanu, E. The Use of Transesterification Method for Obtaining Phosphorus‐Containing Polymers. Advances in Polymer Technology 2014, 33, n/a-n/a.

 

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

I am satisfied with the improvements made by the authors. The paper may be accepted in its current form.

Author Response

Dear Reviewer,

Thank you for your positive comments and thank you again for reviewing our manuscript.

Yours sincerely,

Shang Gao on behalf of all the co-authors.

12 September 2024.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have answered to my comments and made modification in the text accordingly, except for the comment 2. In this case, as the radial effect is not present, the authors should plot MCP mass fraction versus x/L in order to understand the difference between the various cases:

 

Please modify figure 6 and 8 accordingly

Author Response

Dear Reviewer,

 

We gratefully thank for your time spend making your constructive remarks and useful suggestions, which has significantly raised the quality of our manuscript and has enable us to improve the manuscript. According to your suggestions, we have made extensive revisions to our previous draft. The detailed point-by-point responses are listed below.

 

Reply to the comments on processes-3164131 “Numerical simulation and response surface analysis of esterification of monobutyl chlorophosphate with n-butanol in a microchannel reactor”.

 

Response to Reviewer#2

Comments 1: In this case, as the radial effect is not present, the authors should plot MCP mass fraction versus x/L in order to understand the difference between the various cases. Please modify figure 6 and 8 accordingly.

Response 1:

Thank you for your advice. We have redrawn Figures 6 and 8 and rewritten the content associated with them (with red font). Compared with the original contour images, the redrawn images reflect the changes of the mass fraction of the reactants along the flow direction.

 

Figure 6. Variation trend of MCP mass fraction along flow direction with different length-to-diameter ratio.

“Figure 6 illustrates the variation of the mass fraction of the reactant MCP along the flow direction (x/L) under different length-to-diameter ratios. It’s obvious that the reactant is consumed ceaselessly as flow goes. The larger the length-to-diameter ratio, the more the mass fraction of the reactant decreases, which means the conversion rate of MCP will also increase.” (Page 8)

 

Figure 8. Variation trend of MCP mass fraction along flow direction with different n-butanol/MCP mass ratio.

“Figure 8 illustrates the variation trend of MCP mass fraction in the microchannel along the flow direction under different inlet component mass ratios. In the inlet region (x/L < 0.1), the reactants are consumed acutely, especially in the case of relatively high component mass ratios (mass fraction of n-butanol/MCP: 10:5, 10:7, 10:9).” (Page 10)

 

The above is all the changes we have made according to your comments. Thank you again for your positive comments and valuable suggestions to improve the quality of our manuscript, we hope the revised manuscript could be acceptable for you.

 

Yours sincerely,

Shang Gao on behalf of all the co-authors.

12 September 2024.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Good Day,

The authors performed the required modifications in agreement with reviewers recommendations. Now the manuscript improved significantly.

Therefore, I strongly recommend the accpetance for publication.

Best regards!

Comments for author File: Comments.docx

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have positively addressed my suggestions.

Comments on the Quality of English Language

No comments on the quality of English