Catalytic Technologies for CO Hydrogenation for the Production of Light Hydrocarbons and Middle Distillates

Round 1

Reviewer 1 Report

To the authors,

 

it's a article quite interesting revealing up-to-date novelties about the utilisation of heterogeneous catalysts for FTS process. It's suitable for publication in Catalysts jornal.

 

Nevetheless, some moderate english changes are required. In some parts of the text, it's written with "us, we" and, it must be change employing the 3rd person of the singular. Other corrections in the grammar and in the ortography must be corrected.

 

For an review article, the number of references could be signifficantly higher, since there are more substantive references related with the utilisation of FTS process and, the role of Co and Fe catalysts, the diffferences of temperatures in FTS process (lower temperature and higher temperature), the influence of nickel catalyst which enhances methane selectivity, etc. It's suggested to improve this review article, searchinfg and adding more signifficant references regarding FTS process.

 

Some pictures could have better resolution.

Author Response

We sincerely responded to reviewer’s comments.

 

Sincerely yours,

 

Suk-Hwan Kang

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors are presenting a review paper covering the topic of catalysis for short and middle chain hydrocarbons with a focus on Fisher-Tropsch synthesis processes. They analysed the topic considering FTS reaction mechanisms, catalysts materials and manufacturing and reactor configurations, with a focus on some enhancements reached in South Korea. 

The work presents an interesting summary of information, however considerations should be addressed to improve the quality of the work. The authors have properly addressed different topics related to the synthesis of light hydrocarbons and middle distillates and the sections are well separated in topics. However, section 2 requires increased effort to provide a better overview of the FTS mechanisms as well as a higher detail in describing literature works about promoters and active materials. Sections 3 and 4 are well presented in topics, and some minor suggestions for improvement are here provided. However, the English language must improve: the use of external check tool is suggested.

Minor comments:

The aim of this review should be addressed providing the reasons behind the choice of reviewing the South Korean experience. Given the elevated number of authors, please include the “Author contributions” section as suggested by the journal, with specifics for each author. Every figure taken by other works should be cited also in the figure caption and not only in the main text. Figure 1 presents mathematical operators like “<” and “>” with the presence of “*”. The authors should give information about these operators and the numbers beside them and how are they related to syngas, with information about the “*”. In line 55 the authors say “This review is divided into 6 sections”. However, only 5 sections are mentioned. In line 90 the authors use the word “break”. Could the authors provide a clarification on this term connected to the ASF distribution? Table 2 presents catalysts in the first column with codes that are not easily connected to anything else in the text. Please adjust the text accordingly. Intro sentence in line 146 should differ from line 137 to make the text more fluid. Line 189 presents a missing “table 2” word. In line 246 the authors refer to Figure 14 and different manufacturing techniques: no info about these techniques are given with respect to the figure and the different points depicted in it are not clear to the reader. Could the authors explain what they mean with “hard hydrocarbons” in line 436? Given the high number of images, figure 23 could be left out from this study. Figure 30 in line 12bis should be described more in detail. Section 3 is well presented, however an introduction on more traditional techniques for catalyst development could be profitable (e.g. impregnation and precipitation) In line 307 and 309 of section 4.1.3 the authors address “this study” and “these studies”. Can you please provide references? In line 402/403 the authors say “Notable is that most of these studies were reported mainly by the researches from Japan and South Korea”. Could the authors clarify/modify their statement? Much scientific effort is also spent on this topic in other countries like Iran, Norway, Germany, US. An important effect of the synthesis of either short or long chain hydrocarbons is obtained with a variation of the molar ratio at the inlet of the FT reactor H2/CO. The authors mention this ratio several times in their text. It is suggested to provide a section/paragraph covering this topic. The title should focus less on the South Korea country as this is only covered in one section of the paper.

Major comments:

In section 2, the authors analysed the mechanisms for Fischer-Tropsch synthesis. These are mentioned to be called "carbide, enol and CO insertion mechanism" with Figure 3. In line 98 they refer to them as "competition model, carbide model and slow activation model". Moreover, a forth mechanism of FT reaction is accepted by the scientific community as possible one, the alkenyl mechanism. The authors should include a better description of all these mechanisms (using only one name to address to them), with recent reference works available in Catalysts and other scientific journals covering topics of FTS and catalysis. Unless the authors precisely justify and compare their choices, references present in Section 4 should only comprise works of authors from South Korea. In line 125 the authors mention Os as possible catalyst material. However, they do not provide any further information about pros and cons of its application as they do for Ni, Co, Fe and Ru. Could the authors clarify the use of the word “novel” when talking about the ruthenium catalyst in line 127? Up to date, Ru has been an intensively studied catalyst in FTS and is only considered expensive and rare as the authors correctly point out in line 128. In section 2.3, 10 references have been inserted, without any description of their content. Contrarily, no references are given in section 2.4. Please revise your manuscript with a more precise analysis in these section with respect to the cited studies. Even though the authors correctly mention in line 65/66 of section 4.4 “Although these studies are different field with FTS, but it is promising technology of the catalyst design field”, section 4.4 is out topic in this review. Instead, the authors are suggested to remove this section and include detailed information about a novel application in FTS catalyst preparation like the atomic layer deposition technique. The manuscript requires intensive English language checks. Some errors examples are given here below. Also, the same English level and style should be found in every section of the manuscript.

Some example of cerrections related to the English language:

No sentence should start with “And” The word “literature” should be addressed as “work/study/analysis…” (e.g. in line 126). Line 23: of them -> on their design Line 24/24: is not easily understood Line 36 is a repetition of line 34 Line 38: was had -> had Line 58: desiring -> desired Line 73 is not easily understood Line 126/127: There is many literature that -> There is much literature for Line 129: it have too more -> it has too much Line 140: there is -> there are Line 403: differently -> different …

 

 

Author Response

We sincerely responded to reviewer’s comments.

 

Sincerely yours,

 

Suk-Hwan Kang

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The authors are kindly asked to provide evidence and correlation of section 4.4 to the rest of the review paper, in terms of novelty of the presented process of section 4.4 to the FT synthesis reaction and Co hydrogenation. 

 

 

Author Response

Catalysts

Assistant Editor: Ms. Asteria Wang

E-mail: [email protected]

Dear Ms. Asteria Wang,

Thank you for your kind letter of Dec. 22, 2015, with the valuable comments by the reviewer for our manuscript entitled “Catalytic Technologies for CO Hydrogenation for the Production of Light Hydrocarbons and Middle Distillates” which we submitted for publication in Catalysts-MDPI (catalysts-670967) and thank you for your helpful remarks concerning our manuscript. And I am returning herewith the above manuscript revised according to the comments of reviewer 2.

We should like to thank the referees for their comments. And all the comments of the reviewer were carefully considered to the revised manuscript. There were most helpful and gave us a better perspective of our work. I feel that the revised manuscript is a great improvement on their original. I hope that you will think so too and will now accept it for publication in Catalysts. And if this manuscript is acceptable in this journal, Dr. Kang hopes to pay as soon as possible because of the due date of the funding project related to this manuscript. Thank you for your patience and interest.

Additionally, we feel the need to be informed you that the title is changed and funding stats are added as follows:

"Title: Catalytic Technologies for CO Hydrogenation for the Production of Light Hydrocarbons and Middle Distillates: A state-of-Arts in South Korea"

"Acknowledgment: This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) and the Ministry of Trade, Industry& Energy (MOTIE) of the Republic of Korea (No.20173010050110). This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2019R1A6A3A01096215)."

 

Very sincerely yours,

Jae Chang Kim

 

 

Response to Reviewer 2 Comments

 

Point 1: The authors are kindly asked to provide evidence and correlation of section 4.4 to the rest of the review paper, in terms of novelty of the presented process of section 4.4 to the FT synthesis reaction and Co hydrogenation.

 

Response 1:

As the referee’s comments, we added the sentences at the front of section 4.4 as follows:

“As mentioned previously in section 3.3, from the reports of Ponec, Liu et al., and Chen et al., the FTS activity and selectivity affected by the differences of the particle size and crystal phase (e.g. FCC or HCP). And other works are globally reported similar results, recently. So, well-organized (size and shape) nano-manufacturing technology is one of the reasonable approaches to enhance the activity and selectivity. In South Korea, there are some researches related to zeolite supported catalysts and nano-sized active materials. However, there are no approaches related to well-organized shaped catalysts.”

 

And we revised the sentences at the end of section 4.4 as follows:

“Although these studies are in fields (for fuel cells and water electrolysis) unrelated to FTS, if these nano-level manufacturing technologies are collaborating with the FTS catalyst design, there are promising from the perspective of catalyst design in South Korea.”

 

 

And some more scripts are revised as follows:

line 245 – “Because the different morphologies by the crystal phases affect the electronic stats and they result in substantial activity and selectivity [93,94].”

 

Author Response File: Author Response.pdf