Round 1

Reviewer 1 Report

The reviewer paper reports on catalytic pyrolysis of the urban plastic waste in the presence of ZSM-5 and MOR zeolites modified by desilication. Unfortunately, I have to say that the manuscript suffers from many shortcomings and I cannot recommend it for publication. The presented data lead to the conclusion that the influence of MOR zeolites on the catalytic pyrolysis of plastics is very small, significantly smaller than the influence of ZSM-5 zeolite, which has been reported many times (e.g. Tarach et al. ChemSusChem 12 (2019) 633; Lin et al. Renewable energy 164 (2021) 87; Garcia et al. J. Anal. Appl. Pyrolysis 74 (2005) 370 etc.), so the benefit of this study is very small. Shortcomings are also in the presentation and discussion of experimental data and hypotheses (see list below):

• NMR spectra are not mentioned in the manuscript at all, the spectra need to be seen to assess the authors' claims.
• The TPD curves are strange, in most cases the typical high temperature peak characteristic of NH₄⁺ cation decomposition at Bronsted acid sites is missing. This is very strange and leads to doubts as to whether they have Bronsted acid sites at all. It is necessary to supplement the data on FT-IR degassed samples and analyze in detail the O-H vibration.
• on page 3, the authors state "The mordenite porous system is too small for most molecules, which allows the diffusion of only small molecules such as nitrogen and oxygen gases through their pores". I do not agree with this statement, the size of the main MOR channel of the zeolite is significantly larger than the channels in the MFI zeolite. The difference is in the dimensionality of the channel structure (1D / 2D vs. 3D).
• The authors present in Table 1 Si/Al _bulk and Si/Al_surface determined by EDX and EDS. The difference in surface sensitivities of EDX and EDS is debatable, if the authors want to know the composition of the surface layer, it is better to use XPS or Auger spectroscopy.
• 3 - Are the adsorption isotherms shifted in the y-axis direction? It seems to me that it is. But then it must be mentioned in the caption of the picture!
• 4 - ZSM-5/AS sample is missing in the picture. Why?
• 5 - Both ZSM-5/AS and MOR/AS are missing here. Why?
• 6 - what the yield "solid" - needs to be defined.
• page 10 - the authors present "Although presenting a lower overall conversion than ZSM-5/02 and only a small improvement to the blank PMix, both MOR / 02 and MOR / SD showed potential catalysts in the pyrolysis of urban plastic waste conversion into valuable by-products ". I do not agree with this statement. The data do not prove this.

In addition, the manuscript has a number of formal shortcomings, most notably a lack of information regarding the conditions and conduct of the experiments, such as:

• a description of the MOR/AS sample desilication conditions is missing
• a description of MOR/SD synthesis conditions is missing
• information on degassing of samples before measurement of adsorption isothers is missing, which is an important information as it can have a big effect on the resulting textural properties
• missing information about the used thicknes curve equation in BJH and t-plot
• details on TPD experiments are missing
• there is no information on the implementation of pyrolysis of plastics in the reactor (what was the arrangement of the thermal degradation zone and catalytic reforming zone, what was the amount of catalyst and plastics, etc.)

It is not appropriate to refer to other publications (in addition to other authors) - on the one hand it is inconvenient for readers, because they have to look in other publications for details of experiments conducted in this study and it is not clear whether the authors had exactly the same type of device and used exactly the same conditions. Everything has to be stated here in the manuscript exactly according to reality - how the experiments were actually performed. If it took up a lot of space and disproportionately lengthened the manuscript, there is a possibility to use Supplementary information.

Author Response

Manuscript ID chemistry-1593216

Thermal and catalytic pyrolysis of urban plastic waste: modified mordenite and ZSM-5 zeolites

Response to Reviewer

The authors would like to thank the reviewers for their valuable comments and suggestions on the structure and scientific aspects that improved our manuscript. Amendments were provided accordingly. Responses to each comment, point by point, are listed below, and all modifications/additions were marked in the revised version of the manuscript.

Reviewer #1 comments:

The reviewer paper reports on catalytic pyrolysis of the urban plastic waste in the presence of ZSM-5 and MOR zeolites modified by desilication. Unfortunately, I have to say that the manuscript suffers from many shortcomings and I cannot recommend it for publication. The presented data lead to the conclusion that the influence of MOR zeolites on the catalytic pyrolysis of plastics is very small, significantly smaller than the influence of ZSM-5 zeolite, which has been reported many times (e.g. Tarach et al. ChemSusChem 12 (2019) 633; Lin et al. Renewable energy 164 (2021) 87; Garcia et al. J. Anal. Appl. Pyrolysis 74 (2005) 370 etc.), so the benefit of this study is very small.

Response: The authors thank the reviewer for this summary. Despite being extensively studied, our work is unique as a first investigation on the influence of MOR zeolites modified on the pyrolysis of a polymer waste mixture.  Its novelty is emphasized in the revised version. The authors hope that considering the reviewer's comments, the new revised version of our manuscript might be accepted after all the modifications.

Shortcomings are also in the presentation and discussion of experimental data and hypotheses (see list below):

• NMR spectra are not mentioned in the manuscript at all, the spectra need to be seen to assess the authors' claims.

Response: The authors thank the reviewer for the comments and major recommendations that certainly improve our manuscript. The NMR spectra are included in the supporting information, as suggested.

• The TPD curves are strange, in most cases the typical high temperature peak characteristic of NH₄⁺ cation decomposition at Bronsted acid sites is missing. This is very strange and leads to doubts as to whether they have Bronsted acid sites at all. It is necessary to supplement the data on FT-IR degassed samples and analyze in detail the O-H vibration.

Response: The authors thank the reviewer for the comments. We classified the strength of the acid sites according to the desorption temperature, as in most works in the literature.

• on page 3, the authors state "The mordenite porous system is too small for most molecules, which allows the diffusion of only small molecules such as nitrogen and oxygen gases through their pores". I do not agree with this statement, the size of the main MOR channel of the zeolite is significantly larger than the channels in the MFI zeolite. The difference is in the dimensionality of the channel structure (1D / 2D vs. 3D).

Response: This is an important point, which is now addressed in the revised version considering the contribution of the referee.

• The authors present in Table 1 Si/Al_bulk and Si/Al_surface determined by EDX and EDS. The difference in surface sensitivities of EDX and EDS is debatable, if the authors want to know the composition of the surface layer, it is better to use XPS or Auger spectroscopy.

Response: The authors thank the reviewer for the suggestion. We already used three complementary techniques to characterize the zeolite composition.

3 - Are the adsorption isotherms shifted in the y-axis direction? It seems to me that it is. But then it must be mentioned in the caption of the picture!

Response: The authors thank the reviewer for pointing out this important information. In the reviewed version, we included that the isotherms were plotted according to each zeolite's absolute values of adsorbed quantities. Therefore, we included these in the figure capture.

4 - ZSM-5/AS sample is missing in the picture. Why?

Response: The authors thank the reviewer for this comment. We did not obtain the results regarding these unmodified materials.

5 - Both ZSM-5/AS and MOR/AS are missing here. Why? 

Response: The authors thank the reviewer for this comment. We did not obtain the pyrolysis results regarding the unmodified materials since the objective would be to test the materials after the modifications were carried out.

6 - what the yield "solid" - needs to be defined.

Response: As requested, the authors included the definition on pgs.10 and 15. We thank the referee for noticing it.

• page 10 - the authors present "Although presenting a lower overall conversion than ZSM-5/02 and only a small improvement to the blank PMix, both MOR / 02 and MOR / SD showed potential catalysts in the pyrolysis of urban plastic waste conversion into valuable by-products ". I do not agree with this statement. The data do not prove this.

Response: The authors thank the reviewer for the comments and agree. In the reviewed version, we improved this statement, saying that they have the potential for new developments.

In addition, the manuscript has a number of formal shortcomings, most notably a lack of information regarding the conditions and conduct of the experiments, such as:

• a description of the MOR/AS sample desilication conditions is missing –

Response: The authors apologize for not being clear on this point. This sample did not undergo a desilication process.

• a description of MOR/SD synthesis conditions is missing –

Response: The authors also apologize for not being clear regarding this point.  The description of MOR/SD synthesis conditions is shown in section 4.3. Synthesis of Mordenite.

• information on degassing of samples before measurement of adsorption isothers is missing, which is an important information as it can have a big effect on the resulting textural properties

Response: The authors thank the reviewer for calling attention regarding this proceeding. We included in the revised version that the degassing is automatically done in the device used.

• missing information about the used thicknes curve equation in BJH and t-plot

Response: The authors thank the reviewer for noticing the missing information included in the revised version of the manuscript. Pg. 14.

• details on TPD experiments are missing

Response: The authors thank the reviewer for noticing the missing information. We have not detailed because these were published in the other article. However, we included the following in the revised manuscript: The total acidity and strength distribution of the acid sites present in the catalysts were evaluated by the temperature-programmed desorption (TPD-NH3) technique, as described by Paula et al. [29].

• there is no information on the implementation of pyrolysis of plastics in the reactor (what was the arrangement of the thermal degradation zone and catalytic reforming zone, what was the amount of catalyst and plastics, etc.)

Response: The authors included on pg 15 the details regarding the pyrolysis reactor and processes.

It is not appropriate to refer to other publications (in addition to other authors) - on the one hand it is inconvenient for readers, because they have to look in other publications for details of experiments conducted in this study and it is not clear whether the authors had exactly the same type of device and used exactly the same conditions. Everything has to be stated here in the manuscript exactly according to reality - how the experiments were actually performed. If it took up a lot of space and disproportionately lengthened the manuscript, there is a possibility to use Supplementary information.

Response: The authors agree with the comment. We briefly explained the experimental proceeding in each text part in the revised version.

Reviewer 2 Report

This article deals with the possible treatment of waste plastics by catalytic pyrolysis using variously modified zeolites ZSM-5 and mordenite. This topic is interesting and currently actual, however, some changes and refinements are needed.

Apart from the English (use of inappropriate words and phrases see e.g. line 423), the graphical layout of the graphs needs to be standardized (the grid in the graphs is somewhere, somewhere not, etc.). The paper does not sufficiently discuss the catalytic data obtained for modified zeolites with unmodified input zeolites - very often values and graphs for ZSM-5/AS and MOR/AS zeolite are missing, which is important for comparison of properties with modified zeolites.

Other things need to be clarified:

CBV90A is obviously a Zeolyst product, so the manufacturer should be listed, not the distributor.

MOR/AS is in its acidic form, how to understand this? CBV90A=MOR/AS or is MOR/AS an calcined CBV90A. It is also not stated in what form the original CBV90A is.

The chosen heating rate (5°C/min) is quite high for zeolites, usually a much lower rise is used, why was this value chosen?

Why are the conditions not the same for IE zeolites? One time it is 1M, then 2M solution, one time it is desilicated zeolite dried at 80°C, the second time at 200°C, the other time it is calcined at 450°C, then at 550°C?

Add a space between the value and the "%", throughout the document.

Table 1 Need to explain the abbreviation n.d. and EFAL..

Check punctuation, e.g. line 213, no comma before "and" in this case.

LN: 124-125 Rephrase, the sentence does not make sense.

LN:  270 Rephrase.

From line 300 Change tense to past simple.

LN:  344 Rephrase.

LN:  406 How many degrees was it oven-dried?

LN:  417: The ratio is spelled oddly.

Line 423 maceration and sieving? What is meant by this, in the case of the synthesis of zeolites this phrase is not suitable.

LN:  424-426 Rephrase, the sentence does not make sense.

LN: 439 "K" should be "k" and what value was finally substituted into the equation and why?

Characterization:

Add a description of the instruments (manufacturer, city). Also add description of methods to which the authors only refer.

EDX and EDS are the same analysis, the authors have probably confused the product designation EDX-720 with the analysis designation, because the SHIMADZU EDX-720 (if this is the instrument on which the measurement was made) is in fact an X-ray fluorescence spectrometer, i.e. an XRF technique!

NMR: line 465 wrong designation, correct is 27Al MAS NMR + add graphs 29Si and 27Al
MAS NMR

PDF cards for XRD are missing. Add them into the text.

N2 phys.: Add pore distribution plots. In what P/P0 range was the BET determined? At how many points was the isotherm measured? ZSM is a microporous material, which the publishers showed on the t-plot. Publishers used the BJH method to evaluate mesopores, but this method underestimates the material about 25% if the micropores are present. Why was the NLDFT method not used for evaluation, which is also recommended by the ISO standard (ISO 15901-3)? Likewise, due to the presence of micropores, this is an apparent surface (add this note to the catalyst characterization). When moving the isotherm on the y-axis, the values should be removed and a scale should be used instead.

NH3-TPD instrument and measurement conditions are not written, data for ZSM-5/AS is missing in the text, why?

Fig. 5: For comparison, it would be good to add graphs for unmodified zeolites ZSM-5/AS and MOR/AS

Table 5: missing data for ZSM-5/AS, why?

Pyrolysis in Reactor: missing data for ZSM-5/AS and MOR/AS.

Specific product identification is missing, what is the main component of the gaseous products when using the ZSM-5/02 catalyst? So what are the main components of the liquid products specifically?

Light fraction definition is missing (the reader may not be from the branch and therefore, may not understand).

Discussion

This is not a discussion, but rather a review. It is not a discussion of authors own results (which are summarized in only 6 lines), but primarily the results of others. There should at least be a broader comparison.

Author Response

Manuscript ID chemistry-1593216

Thermal and catalytic pyrolysis of urban plastic waste: modified mordenite and ZSM-5 zeolites

Response to Reviewer

The authors would like to thank the reviewers for their valuable comments and suggestions on the structure and scientific aspects that improved our manuscript. Amendments were provided accordingly. Responses to each comment, point by point, are listed below, and all modifications/additions were marked in the revised version of the manuscript.

Reviewer #2 comments:

This article deals with the possible treatment of waste plastics by catalytic pyrolysis using variously modified zeolites ZSM-5 and mordenite. This topic is interesting and currently actual, however, some changes and refinements are needed.

Apart from the English (use of inappropriate words and phrases see e.g. line 423), the graphical layout of the graphs needs to be standardized (the grid in the graphs is somewhere, somewhere not, etc.). The paper does not sufficiently discuss the catalytic data obtained for modified zeolites with unmodified input zeolites - very often values and graphs for ZSM-5/AS and MOR/AS zeolite are missing, which is important for comparison of properties with modified zeolites.

Response: The authors thank you for the comments. The graphs are found with vertical grids to aid in reading the result. The graphs referring to the TGA curves present vertical and horizontal grids to facilitate the reading of the graph

Other things need to be clarified:

CBV90A is obviously a Zeolyst product, so the manufacturer should be listed, not the distributor. Response: The authors thank the reviewer and apologize for the misunderstanding. The revised version was improved.

MOR/AS is in its acidic form, how to understand this? CBV90A=MOR/AS or is MOR/AS an calcined CBV90A. It is also not stated in what form the original CBV90A is.

Response: The authors apologize for not being clear on this point. The revised version was improved. The original mordenite, code CBV90A was named MOR/AS.

The chosen heating rate (5°C/min) is quite high for zeolites, usually a much lower rise is used, why was this value chosen? Why are the conditions not the same for IE zeolites? One time it is 1M, then 2M solution, one time it is desilicated zeolite dried at 80°C, the second time at 200°C, the other time it is calcined at 450°C, then at 550°C?

Response: All methodologies were based on references in the area. Different zeolites presented different chemical treatment and calcination conditions.

Add a space between the value and the "%", throughout the document. –

Response: The authors thank the reviewer for noticing. We changed as suggested.

Table 1 Need to explain the abbreviation n.d. and EFAL.

Response: The authors thank the reviewer. We included the information as suggested.

Check punctuation, e.g. line 213, no comma before "and" in this case.

Response: The authors thank the reviewer. We checked the punctuation overall in the revised version.

LN: 124-125 Rephrase, the sentence does not make sense.

Response: The authors totally agree with the referee. We changed the sentence to “This result can be justified since, during desilication, Si species not linked to Al, Si (0Al), can be easily leached.”

LN:  270 Rephrase.

Response: The authors thank the reviewer. We changed the phrase as recommended.

From line 300 Change tense to past simple.

Response: The authors agree with the referee and made the necessary changes in the revised version of the manuscript.

LN:  344 Rephrase.

Response: The authors thank the reviewer. We also changed this phrase.

LN:  406 How many degrees was it oven-dried?

Response: The authors thank the reviewer for the comment. We modified the text on pg. 12 accordingly. We also included on pg. 13, the sentence “The solid was centrifuged and washed three times with warm water and oven-dried at 80°C overnight.”

LN:  417: The ratio is spelled oddly.

Response: The authors thank the reviewer, we corrected it.

Line 423 maceration and sieving? What is meant by this, in the case of the synthesis of zeolites this phrase is not suitable.

Response: The authors thank the reviewer for the comment. We corrected this part of the text.

LN:  424-426 Rephrase, the sentence does not make sense.

Response: The authors thank the reviewer for the comment. We changed the sentence to clarify the text.

LN: 439 "K" should be "k" and what value was finally substituted into the equation and why?

Response: The authors thank the reviewer for the comment. We changed this part of the text in the revised version.

Characterization:

Add a description of the instruments (manufacturer, city). Also add description of methods to which the authors only refer.

Response: The authors thank the reviewer for improving the paper; we agree with the comment and include the description of all the instruments in the revised version.

EDX and EDS are the same analysis, the authors have probably confused the product designation EDX-720 with the analysis designation, because the SHIMADZU EDX-720 (if this is the instrument on which the measurement was made) is in fact an X-ray fluorescence spectrometer, i.e. an XRF technique!

Response: The authors apologize for the misunderstanding. We performed in all the samples the EDX technique. Regarding the microscopy analysis, we used an X-ray energy dispersive spectroscopy (EDS) coupled with the scanning electron microscope (SEM-EDS) that analyzes the localized elemental composition, as now indicated in the revised manuscript.

NMR: line 465 wrong designation, correct is 27Al MAS NMR + add graphs 29Si and 27Al
MAS NMR

Response: We apologize for the mistake, which is now addressed in the revised version.

PDF cards for XRD are missing. Add them into the text.

Response: The authors thank the reviewer for the comment. We included the standard spectra for XRD in the supporting information.

N2 phys.: Add pore distribution plots. In what P/P0 range was the BET determined? At how many points was the isotherm measured? ZSM is a microporous material, which the publishers showed on the t-plot. Publishers used the BJH method to evaluate mesopores, but this method underestimates the material about 25% if the micropores are present. Why was the NLDFT method not used for evaluation, which is also recommended by the ISO standard (ISO 15901-3)? Likewise, due to the presence of micropores, this is an apparent surface (add this note to the catalyst characterization). When moving the isotherm on the y-axis, the values should be removed and a scale should be used instead.

Response: The authors thank the reviewer for the comments. We included information in the revised version of the manuscript.

NH3-TPD instrument and measurement conditions are not written, data for ZSM-5/AS is missing in the text, why?

Response: The authors thank the reviewer for this comment. In fact, pyrolysis was not performed with unmodified materials

Fig. 5: For comparison, it would be good to add graphs for unmodified zeolites ZSM-5/AS and MOR/AS. Table 5: missing data for ZSM-5/AS, why? Pyrolysis in Reactor: missing data for ZSM-5/AS and MOR/AS.

Response: The authors thank the reviewer for this comment. In fact, pyrolysis was not performed with unmodified materials, and those materials were not characterized either.

Specific product identification is missing, what is the main component of the gaseous products when using the ZSM-5/02 catalyst? So what are the main components of the liquid products specifically?

Response: The authors thank the reviewer for this comment. The exact identification of the products was not performed. For its accuracy, fractional distillation chromatography equipment was required. We only used mass spectroscopy, which with the diesel standard, we were able to estimate the amount of a chain sizes range but not quantify each chain size resulting from the pyrolysis.

Light fraction definition is missing (the reader may not be from the branch and therefore, may not understand).

Response: The authors thank the reviewer for this comment. The text defines the light fraction as light compounds (C10-C24) in pyrolysis liquid products.

Discussion

This is not a discussion, but rather a review. It is not a discussion of authors own results (which are summarized in only 6 lines), but primarily the results of others. There should at least be a broader comparison.

Response: The authors thank the reviewer for the comment. We improved the text in the revised version.

Reviewer 3 Report

This ms. combines several techniques to report the catalytic activity of synthesized and chemically modified mordenite in pyrolysis of a of plastic waste showing featuring  small increase of light hydrocarbon compounds (C10-C24) in pyrolysis liquid products compared to ZSM-5 in spite of the higher mesoporosity and lower deactivation susceptibility of the latter.

I found minor issues which needs to be amended:

line 25-26: mordenite appears to have lower (not higher, as stated) values

lines 164-166: crystallite size by Scherrer equation taking a single line neglects the anisotropic broadening due to non-isometric crystallite shape, whole profile fit is recommended to achieve reliable crystallite size.

lines 185-187 repetition

lines 448-450 "Energy dispersion spectroscopy (EDX)" must be replaced by "Energy Dispersive X-ray Fluorescence Spectrometry (ED-XRF)" here and throughout the text. The code "EDX" is just with the Shimadzu Series EDX model.

Author Response

Manuscript ID chemistry-1593216

Thermal and catalytic pyrolysis of urban plastic waste: modified mordenite and ZSM-5 zeolites

Response to Reviewer

The authors would like to thank the reviewers for their valuable comments and suggestions on the structure and scientific aspects that improved our manuscript. Amendments were provided accordingly. Responses to each comment, point by point, are listed below, and all modifications/additions were marked in the revised version of the manuscript.

Reviewer #3 comments:

This ms. combines several techniques to report the catalytic activity of synthesized and chemically modified mordenite in pyrolysis of a of plastic waste showing featuring  small increase of light hydrocarbon compounds (C10-C24) in pyrolysis liquid products compared to ZSM-5 in spite of the higher mesoporosity and lower deactivation susceptibility of the latter.

Response: The authors thank the reviewer for the summary. We thank the referee for the contribution. The issues were addressed as follows.

I found minor issues which needs to be amended:

line 25-26: mordenite appears to have lower (not higher, as stated) values

Response: The authors agree with the reviewer, and thank for noticing. It was corrected in the revised version.

lines 164-166: crystallite size by Scherrer equation taking a single line neglects the anisotropic broadening due to non-isometric crystallite shape, whole profile fit is recommended to achieve reliable crystallite size.

Response: The authors agree with the reviewerand included this comment in the text.

lines 185-187 repetition

Response: The authors thank the reviewer for noticing. We removed the repetition.

lines 448-450 "Energy dispersion spectroscopy (EDX)" must be replaced by "Energy Dispersive X-ray Fluorescence Spectrometry (ED-XRF)" here and throughout the text. The code "EDX" is just with the Shimadzu Series EDX model.

Response: The authors agree with the referee's comment. As requested, the technique's name was changed throughout the revised version.

Round 2

Reviewer 1 Report

The revised manuscript reflected some of my comments, but some fundamental ones remain unresolved. In particular, the low activity of MOR zeolites compared to ZSM-5 (MFI) zeolite still remains undiscussed and unexplained. The effect of MOR zeolite is almost negligible compared to the course of pyrolysis without the presence of a catalyst. If the authors changed the conclusion of the study from "Although presenting a lower overall conversion than ZSM-5/02 and only a small improvement to the blank PMix, both MOR / 02 and MOR / SD showed potential catalysts in the pyrolysis of urban plastic waste conversion into valuable by-products " on the statement " In the reviewed version, we improved this statement, saying that they have the potential for new developments. " there is no discussion of these "new developments" - which, in which direction, etc. Many of my other questions or reservations were not taken into account: for example, the details of degassing samples before experiments (especially measurements of adsorption isotherms) are still not given in the manuscript. Zeolite surface composition information are not cerrectly discussed (ED-XRF and EDS measurements are not sufficient in this respect) and the like. I still don't consider the manuscript suitable for publication.

Author Response

Manuscript ID chemistry-1593216

Thermal and catalytic pyrolysis of urban plastic waste: modified mordenite and ZSM-5 zeolites

Reviewer #1 comments:

(x) English language and style are fine/minor spell check required
The revised manuscript reflected some of my comments, but some fundamental ones remain unresolved. In particular, the low activity of MOR zeolites compared to ZSM-5 (MFI) zeolite still remains undiscussed and unexplained. The effect of MOR zeolite is almost negligible compared to the course of pyrolysis without the presence of a catalyst. If the authors changed the conclusion of the study from "Although presenting a lower overall conversion than ZSM-5/02 and only a small improvement to the blank PMix, both MOR / 02 and MOR / SD showed potential catalysts in the pyrolysis of urban plastic waste conversion into valuable by-products " on the statement " In the reviewed version, we improved this statement, saying that they have the potential for new developments. " there is no discussion of these "new developments" - which, in which direction, etc. Many of my other questions or reservations were not taken into account: for example, the details of degassing samples before experiments (especially measurements of adsorption isotherms) are still not given in the manuscript. Zeolite surface composition information are not cerrectly discussed (ED-XRF and EDS measurements are not sufficient in this respect) and the like. I still don't consider the manuscript suitable for publication.

Response: The authors thank the reviewer for the comments. We made corrections in the text related to the language and the specific points mentioned, in the revised version. We added the textural analysis degassing data into the file.

Regarding the use of the EDS and EDX discussion, the authors decided to change it in the revised version. We changed the discussion withdrawing this statement.

Reviewer 2 Report

Please see the attachment.

Comments for author File: Comments.pdf

Author Response

Manuscript ID chemistry-1593216

Thermal and catalytic pyrolysis of urban plastic waste: modified mordenite and ZSM-5 zeolites

Reviewer #2 comments:

Apart from the English (use of inappropriate words and phrases see e.g. line 423), the graphical layout of the graphs needs to be standardized (the grid in the graphs is somewhere, somewhere not, etc.). The paper does not sufficiently discuss the catalytic data obtained for modified zeolites with unmodified input zeolites - very often values and graphs for ZSM-5/AS and MOR/AS zeolite are missing, which is important for comparison of properties with modified zeolites.

The authors should make the graphs in the same order, because then the work itself doesn’t look professional.

Response: The authors thank the reviewer for the comments. We made corrections in the text related to the language and the specific points mentioned, in the revised version. We added the textural analysis degassing data into the file. The graphics have already been adjusted as requested.

The chosen heating rate (5°C/min) is quite high for zeolites, usually a much lower rise is used, why was this value chosen? Why are the conditions not the same for IE zeolites? One time it is 1M, then 2M solution, one time it is desilicated zeolite dried at 80°C, the second time at 200°C, the other time it is calcined at 450°C, then at 550°C? Response: All methodologies were based on references in the area. Different zeolites presented different chemical treatment and calcination conditions.

It is probably not advisable to take each author's experimental values from each other, it does help that it is easier to compare the results with theirs, but it makes it impossible to compare them with each other in the same paper.

Response: The authors thank the referee. A study was carried out on the existing references for the desilication of different zeolites. The different methodologies seek to respect the characteristics of each zeolite, with different chemical treatments and calcination, and different capacity for the formation of mesopores. The comparison made in this work is related to the fact that ZSM-5 is a zeolite commonly studied in the pyrolysis of plastics, being used only as a reference in this work.

N2 phys.: Add pore distribution plots. In what P/P0 range was the BET determined? At how many points was the isotherm measured? ZSM is a microporous material, which the publishers showed on the t-plot. Publishers used the BJH method to evaluate mesopores, but this method underestimates the material about 25% if the micropores are present. Why was the NLDFT method not used for evaluation, which is also recommended by the ISO standard (ISO 15901-3)? Likewise, due to the presence of micropores, this is an apparent surface (add this note to the catalyst characterization). When moving the isotherm on the y-axis, the values should be removed and a scale should be used instead. Response: The authors thank the reviewer for the comments. We included information in the revised version of the manuscript.

Response: the authors added the ASAP conditions in the text, as suggested by the reviewer.

The scale still has not been included in the isotherm graphs, which is very important in order to read the measured data correctly. Also, authors started to write only about mesopores, however the micropores are at these materials important. BJH method is good to use for mesopores, however it should not be used for specifying the micropores, because it undervalues. This needs to be corrected. Number of isotherm points are also missing.

Response: The authors have already placed the isotherm points in the work, which are presented in the graph. The scale is in cm³/g.

Fig. 5: For comparison, it would be good to add graphs for unmodified zeolites ZSM-5/AS and MOR/AS. Table 5: missing data for ZSM-5/AS, why? Pyrolysis in Reactor: missing data for ZSM-5/AS and MOR/AS. Response: The authors thank the reviewer for this comment. In fact, pyrolysis was not performed with unmodified materials, and those materials were not characterized either.

How can there be an experiment without comparing it to the source material? Where is the certainty that the modification helped if there is nothing to compare it to? NH3-TPD and pyrolysis experiments need to be measured on the source material to compare it.

Response: The objective of the work is to evaluate the performance of only the modified zeolites, as mentioned in the text. Unmodified zeolites are not suitable for use as catalysts, as it is necessary to develop pores with adequate sizes to allow pyrolysis of macromolecules.

 Specific product identification is missing, what is the main component of the gaseous products when using the ZSM-5/02 catalyst? So what are the main components of the liquid products specifically? Response: The authors thank the reviewer for this comment. The exact identification of the products was not performed. For its accuracy, fractional distillation chromatography equipment was required. We only used mass spectroscopy, which with the diesel standard, we were able to estimate the amount of a chain sizes range but not quantify each chain size resulting from the pyrolysis.

I think this figure is very important for further possible use. If the technique is not available at the workplace, it can certainly be done externally.

Response: We can no longer analyze the oils obtained in the pyrolysis, the analyzes performed are in accordance with the works in the literature. The gases are analyzed at the time of pyrolysis.

Discussion This is not a discussion, but rather a review. It is not a discussion of authors own results (which are summarized in only 6 lines), but primarily the results of others. There should at least be a broader comparison. Response: The authors thank the reviewer for the comment. We improved the text in the revised version.

SI: What are the numbers on the green axes of some of the graphs? Summary It seems that only "cosmetic" authors have made. The paper needs further editing (unifying the style of the graphs, etc.) and certainly some further experiments (NH3-TPD and pyrolysis experiments for crude zeolites) are needed to confirm or refute the data presented in the paper and to disprove the "conjectures". As for the N2-physisorption, none of our question has been answered, such as p/p0 range and etc. In our opinion, it is not possible not to perform the same experiment with unmodified materials, because only here it will become clear if the modification led to improved properties. Thanks to editing, Table 1 and 6 have been displaced.

Response: the authors made some changes in the discussion in the revised version of the manuscript.