Minireview: Intensified Low-Temperature Fischer–Tropsch Reactors for Sustainable Fuel Production
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis review is based on the absolutely reasonable assumption that due to the low specific energy content of any bioresources and waste, their processing can only be carried out on site, and therefore requires low-tonnage technologies. This also applies to the FTS as one of the promising directions of use of such resources.
The review contains a very clear and informative presentation of the main factors and problems that arise when reducing the scale of FTS. A very complete and objective description of the existing directions and trends in solving these problems, the results achieved so far and potential opportunities is presented. This makes the review very useful and worth publishing.
However, the authors almost completely exclude from consideration the main factor affecting the profitability of the practical implementation of low-tonnage technologies for the conversion of bioresources and waste into synthetic hydrocarbons – the complexity and energy intensity of their preliminary conversion to syngas, consuming up to 60% of all expenses. This is a serious omission, since only a coordinated adaptation of the conversion of bioresources and wastes into syngas and subsequent FTS based on this gas can make it possible to create really low-tonnage technologies. It is necessary to at least mention this problem.
Author Response
Author's Reply to the Review Report (Reviewer 1):
Thank you very much for your helpful review of our paper. We appreciate your comments and we implement them to amend our manuscript.
You are absolutely correct in highlighting the importance of syngas production as a significant factor affecting the overall profitability of low-tonnage technologies for converting bioresources and waste into synthetic hydrocarbons. We acknowledge that the energy intensity and complexity of the syngas generation process.
We added a sentence in introduction and mentioned this (page 2-line 49), we do recognize that biomass-to-syngas conversion is an important step in the process. However, the primary focus of this review is on the intensification of the Fischer-Tropsch synthesis (FTS) reactor, which represents a critical stage in the process. Our aim was to address the challenges and opportunities specific to improving the efficiency and scalability of FTS reactors, with an emphasis on their role in enhancing the overall process.
Reviewer 2 Report
Comments and Suggestions for AuthorsThis manuscript discusses the intensification technologies for Low-Temperature Fischer-Tropsch (LTFT) reactors, including emerging technologies such as microchannel reactors, structured reactors, cross-flow reactors, fixed-bed membrane reactors, and coupled reactors. The content is detailed and well-supported by recent research. However, before publication, the following issues should be addressed:
1. Font Size Consistency: Ensure that the font size is uniform throughout the manuscript. For example, in Table 4, the text "2-the reactors is used for other reaction (i.e. methanation) and not for FTS" has an oversized "the", which needs adjustment.
2. Temperature Indications for Thermal Conductivity in Table 3: The thermal conductivity values in Table 3 should explicitly specify the corresponding temperatures.
3. Economic Viability of Microchannel Reactors: The manuscript emphasizes the superior catalyst utilization efficiency of microchannel reactors compared to traditional reactors. However, does the microchannel reactor also demonstrate better production capacity and economic efficiency? This should be further discussed and supported with data.
4. Recent Commercialization Cases: Are there any large-scale BTL/GTL plants that have adopted microchannel reactors? Have any new commercialization cases emerged in the last two years? It is recommended to add a future industrialization trend analysis at the end of the manuscript.
5. Comparison of Energy or Thermal Efficiency: Can the manuscript include a comparison of energy efficiency or thermal efficiency among different reactor types? This would provide a clearer understanding of the advantages and trade-offs of each technology.
Addressing these points above will improve the clarity, consistency, and completeness of the manuscript before publication.
Grammar and Typographical Errors: Please review for grammatical issues and typos. For example, in the Conclusion section, the sentence "Concept of coupled reactors, while are promising for efficiency gains and were successfully tested for several chemical reactions, is also lack experimental development involving FTS." contains errors in the usage of "lack" and "while", which should be corrected.
Author Response
Author's Reply to the Review Report (Reviewer 2)
Thank you very much for your helpful review of our paper. We appreciate your comments and we implement them to amend our manuscript.
1. Font Size Consistency: Ensure that the font size is uniform throughout the manuscript. For example, in Table 4, the text "2-the reactors is used for other reaction (i.e. methanation) and not for FTS" has an oversized "the", which needs adjustment. We checked the format of manuscript and tried to unify the fond size throughout the manuscript
2. Temperature Indications for Thermal Conductivity in Table 3: The thermal conductivity values in Table 3 should explicitly specify the corresponding temperatures.
Extra description is added to Table 3 mentioning the corresponding temperatures (room temperature)
3. Economic Viability of Microchannel Reactors: The manuscript emphasizes the superior catalyst utilization efficiency of microchannel reactors compared to traditional reactors. However, does the microchannel reactor also demonstrate better production capacity and economic efficiency? This should be further discussed and supported with data.
In the final section of the manuscript, we have added additional text discussing the commercialization plans of microchannel reactors by a few companies, including their production capacities. We have also provided our perspective on the advantages and disadvantages of these reactors. While we anticipate that CAPEX for microchannel reactors will be higher, their superior heat management capabilities are expected to result in lower OPEX. However, a full economic analysis is beyond the scope of this manuscript, and given the emergence of new reactor technologies, not all economic data have been published yet.
4. Recent Commercialization Cases: Are there any large-scale BTL/GTL plants that have adopted microchannel reactors? Have any new commercialization cases emerged in the last two years? It is recommended to add a future industrialization trend analysis at the end of the manuscript.
We have added a new paragraph before the conclusion outlining recent developments by several companies, including Ineratec, Velocys, and CompactGTL, in the areas of biomass-to-liquid (BTL), gas-to-liquid (GTL), and power-to-liquid (PtL) projects and plans.
5. Comparison of Energy or Thermal Efficiency: Can the manuscript include a comparison of energy efficiency or thermal efficiency among different reactor types? This would provide a clearer understanding of the advantages and trade-offs of each technology.
An additional column has been added to Table 4, comparing the heat duties of intensified microreactors with those of traditional fixed (packed) bed reactors.
