Selective Synthesis of a Gasoline Fraction from CO and H2 on a Co-SiO2/ZSM-5/Al2O3 Catalyst
, Grigory B. Narochnyi 1, Ivan N. Zubkov 1, Ekaterina A. Bozhenko 1, Yash V. Kataria 1, Roman D. Svetogorov 2 and Alexander P. Savost’yanov 1Round 1
Reviewer 1 Report
Reviewer’s Comments:
A manuscript entitled:
“SELECTIVE SYNTHESIS OF A GASOLINE FRACTION FROM CO AND H2 ON A CO-SiO2/ZSM-5/Al2O3 CATALYST”
Presented by:
[R.E. Yakovenko, G.B. Narochnyi, I.N. Zubkov, E.A. Bozhenko, Y.V. Kataria, and A.P. Savost’yanov],
was submitted to Catalysts (an MDPI Journal) for review on 17th August 2023.
A: General Comments
1. Title
The title of the article is suitable for the work presented: The selective synthesis of gasoline fraction from syngas on the named catalyst.
2. Introduction
The literature overview captures existing issues surrounding Fischer-Trosch catalysis on zeolites in industry.
3. Research Objective
The purpose of the study is well articulated, that is, “To search for the synthesis conditions under which gasoline fraction obtained on the target catalyst will be enriched in iso-alkanes, with high antiknock properties” and was this achieved. Well done!
4. Originality
There is some reasonable degree of novelty in the study as evident from the pilot plant. Most studies on novel catalysts in literature are always from micro-reactors on bench scale, but data of new catalysts tested on pilot plants are scarce, and for that, the authors get credit.
5. Research Methods
There is an adequate description of how the catalyst was synthesized and tested on a well-designed pilot FT-reactor system, and catalyst characterization (by BET porosity measurements, microscopy (SEM & TEM) and XRD) are presented.
This seems to me as a missed opportunity for the researchers to have attempted temperature-programmed methods such as TPR and TPD studies, that is, if they have the equipment. For example, TPR would have confirmed the presence of the oxidized species in the cobalt catalyst as indicated by XRD (Figure 2), while TPD would have exposed the acidic nature of the zeolites (with Lewis and/or Bronsted acid sites). This could reveal the potential role acidity plays in the production of the various fractions of the FT-products. The question I have in mind is: “Was the production of the targeted gasoline fraction the product of catalyst micro-porosity only?” A control experiment would have included determining if a comparable mesoporous zeolite catalyst would have produced a diesel-rich FT product stream.
6. The Body
In this work, a method for producing high-octane gasoline from syngas on a pilot scale is presented, where a bi-functional cobalt-zeolite catalyst is used, with better results indicated at lower pressures such as 0.5 MPa as opposed to 2 MPa. The catalyst material and the Fischer-Tropsch reaction products were benchmarked and characterized using established techniques, which makes the research scientifically sound, and acceptable.
7. Summaries
The outlines of the study in the abstract and conclusion are well summarized to capture the main outcomes of the investigation.
8. Conclusion
The manuscript is a well-written piece of work worthy of being considered for publication, but with minor corrections.
9. References
The citations are sufficient, but would have done better to include this important citation:
· “Zeolite-Containing Co Catalysts for Fischer–Tropsch Synthesis with Tailor-Made Molecular-Weight Distribution of Hydrocarbons” by Lilia Sineva, et al., Reactions, (2023).
B: Minor Issues
1. Line 4: Remove the superscripts if all authors are from one institution.
2. Line 8: Take care of subscripts in “H2 on a Co-Al2O3/SiO2/HZSM-5 hybrid”
3. Line 26: There is a missing word in “Fischer-Tropsch (FT) method on an ________ was mastered in Germany”
4. Line 56: Take care of subscripts in: “…catalyst Co-Al2O3/SiO2…”.
5. Line 59: Take care of subscripts in: “…with a SiO2/Al2O3 molar ratio…”.
6. Lines 75, 78, 86 and 88: Are the square brackets “[ ]” meant to have references?
7. Lines 78, 86 and 88: The Equations 1, 2 and 3 have a numbering problem. Please revise.
8. Lines 112 and 161: The “F” in “fig. 1” and “Fig. 2” and, in the rest of the manuscript should be consistent.
9. Line 163: Check repetition of 2-theta in “ …reflexes at 2θ ≈ 2θ ≈ 20.3°, …”
10. Line 175: Images in Figure 4 are fragmented; please group all the images so that they appear as one picture.
11. Line 187: It is preferable to use S(EXT) for external surface area in Table 1 rather than S(EX); and then translate this word “(Пpимeчaниe)” in English.
12. Line 201 and 261: Capitalize the “t” in the text of “table 2” and “table 5”.
13. Line 203: In Table 2, what is o/p?
14. Line 206: What are iso/n and o/n indicators?
15. Line 218: In Table 3, please translate this “(CeлeктивноcÑ‚ÑŒ)” in English.
16. Lines 244, 254 and 257: Take care of the subscripts in “C5+”.
17. Lines 267 – 269: The statement is confusing: Does it refer to this work or other works?
18. Lines 270: What is the “density of your experimental gasoline fraction”?
19. Lines 274: What is the “calorific value of your experimental gasoline fraction”?
20. Lines 278: What is the “iodine number of your experimental gasoline fraction”?
Minor editorials required.
Author Response
In accordance with the comments and recommendations of Review1, the text of the manuscript has been revised. Fragments of the text of the new version of the manuscript are highlighted in blue. Extended responses to comments are provided in the attached file.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript is about SELECTIVE SYNTHESIS OF A GASOLINE FRACTION FROM CO AND H2 ON A CO-SiO2/ZSM-5/Al2O3 CATALYST. The following are the comments to improve the paper:
1. A precise and clear comparison between Literature and the current work is needed to see why the catalyst present in this work is important and how it stands in comparison with already used commercial catalyst.
2. Why is the catalyst deactivating after reaction? There is no reasoning as well as any characterization of the spent catalyst.
3. Why are there 2 different reduction temperatures of 400 C for reduced TEM images and 500 C prior to catalytic reaction? If this is the case then the catalysts after reduction could not be compared to the ones after activation in the reactor. How is the temperature of 400 or 500 C chosen? There is no TPR experiment showing the reduction temperature of the catalyst.
4. What is the composition of the Co-Al2O3/SiO2 catalyst? 20wt% Co, 1wt% Al2O3 and the rest is SiO2? Please clarify. Also it could be informative if you could mention the advantage of using Co-Al2O3/SiO2 with zeolite? why Co-Al2O3/SiO2/HZSM-5 hybrid catalyst is better than Co-Al2O3/SiO2 or Co-HZSM-5 alone?
5. Crystallite size is calculate from XRD and not particle size (line 164 in main text).
6. How is the BET surface area is calculated at P/P0 of 0.2? Usually the BET S.A. is calculated in the range between 0.03 and 0.3. Since the isotherm is already available then it is feasible.
7. Typos: In the abstract No subscript present in H2 on a Co-Al2O3/SiO2/HZSM-5
Rephrase: line (25-26) The first industrial scale production of synthetic gas- 25 oline by the Fischer-Tropsch (FT) method on an was mastered in Germany during the 26 Second World War [4].
Subscript and remove the dot in highlighted words in line (56-57) The cobalt catalyst Co-Al2O3/SiO2 was used for the selective synthesis of long-chain hydrocarbons (20.0 Co and 1.0 Al2O3 wt %) with a silica gel carrier KSKG (OOO Salavat Catalyst Plant) [21], and zeolite HZSM-5 was used as the acid component. with a SiO2/Al2O3 molar ratio of 40.5 (OOO Ishimbay Specialized Chemical Plant of Cat-alysts) [20, 22] and binder boehmite Al(OH)O (Sasol, TH 80).
Remove bracket in line 75, 78, 80 and 86.
Between lines 78 and 79 there is parenthesis with number 10. to be removed.
Between line 86 and 87 there is also a parenthesis with number 1..to be removed.
remove brackets line 88
Between lines 88 and 89 remove parenthesis of number 3.
Line 163 2teta repeated twice (reflexes at 2θ ≈ 2θ ≈ 20.3°, 29.5° and 52.0°)
Figure 2: On the y-axis no title it should be (Intensity (a.u.)). On the x-axis fix the typo degree and not degress
Figure 4: No Scale bars on any of the EDX mapping images. The words on the SEM image are not readable at all.
Table 1: The word before SBET is not understood Пpимeчaниe:
Line 201: The results of these studies are given in table. 2. Remove point after table
Line 208: 83.2 kg/(m3cat. ∙h), respectively. Remove dot
Table 3: Ceлeктивноcть, % Russian word?
Line 229: hydrocarbons was 86.0 kg/(m3cat.∙h) remove dot
Lines 259-261: The results of a study of a number of basic physicochemical and operational indica-tors of a synthesized experimental batch of gasoline fraction of hydrocarbons in are pre- sented in table. 5. Rephrase it is not understandable and remove dot between table and number 5.
subscript Lines 56-57: ‘The cobalt catalyst Co-Al2O3/SiO2 was used for the selective synthesis 56 of long-chain hydrocarbons (20.0 Co and 1.0 Al2O3 wt %) with a silica gel carrier KSKG 57 (OOO Salavat Catalyst Plant)’
8. The format of the references should be checked if it is in the correct form or not. In addition, Fix title of reference 1 , reference 3: Remove bracket at the end, reference 5: all authors should be mentioned, remove ‘et all.’, Reference 25 missing title of publication.
The whole paper should be reread carefully and improve the English and writing.
Author Response
In accordance with the comments and recommendations of Review2, the text of the manuscript has been revised. Fragments of the text of the new version of the manuscript of the article are highlighted in purple. Extended responses to comments are provided in the attached file
Author Response File: Author Response.pdf
Reviewer 3 Report
The paper reports the catalytic testing of the bifunctional catalyst for CO/H2 to gasoline process. The study might of interest to the whole community of readers of Catalysts, however, there is a number of points that needs clarification.
The catalysts were reduced prior to catalytic tests, which is understandable. How were the reduction conditions determined?
Line 164: Authors report the particle size of metallic cobalt while there is no metallic cobalt in the samples according to the XRD analysis. Was it a mistake and it refers to Co3O4?
The Debye Scherrer equation works on XRD data. Are you sure you applied it to TEM technique?
Table 1: there is an inset in Russian.
Moderate language and editorial corrections are required, for instance in the following:
Line 34: MTG abbreviation stands for ‘methanol to gasoline’
Line 26: “method on an was mastered”
Lines 75-88: references are missing
Lines 205-206 “the selectivity (..) increase”
q
Author Response
In accordance with the comments and recommendations of Review3, the text of the manuscript has been revised. Fragments of the text of the new version of the manuscript are highlighted in green. Extended responses to comments are provided in the attached file.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The authors have answered the comments.
few more comments: put on the Y-axis of figure 1 Intensity (a.u.)
2. The scale bar should be also available on the Mapping images in Fig. 3 and not only the TEM.
3. y-axis of fig, 5 should be ( H2 consumption (a.u.))
4. Fig, 9 use same format for the y and x-axis as in figure 1.
English language improved.
Author Response
In accordance with the comments and recommendations of the reviewer, the text of the manuscript has been revised. Extended responses to comments are provided in the attached file.
Author Response File: Author Response.pdf
