K₂O Doped Dolomite as Heterogeneous Catalyst for Fatty Acid Methyl Ester Production from Palm Oil

Round 1

Reviewer 1 Report

This manuscript reported the synthesis of K2O doped dolomite catalysts for the fatty acid methyl ester (FAME) production from palm oil. The authors prepared a series of catalysts with different K2O loading, characterized the samples with different experimental technique and compared the catalytic performance and stability of the samples. They found that the catalyst with 15wt% K2O loading showed the highest yield of FAME and showed satisfactory reusability. Overall, this is an interesting work, which deserves to be publish in catalyst. Therefore, I would suggest a minor revision and my comments are as follows:

1. Since the authors talked about the doping of K2O into the dolomite crystals, they should introduce more on the change in the crystal structures of the dolomite before and after the doping. For example, which sites will be occupied by the K⁺ cations in Figure 1. Is there a saturate doping amount or limits from the literature.
2. Line 102, the authors mentioned a slight shift in the CaO peak at 2theta = 32.4degree with the increasing amount of K+ cations. An additional enlarged XRD patterns should be provided in Figure. 2 to visualize the peak shift. The effect of K+ doping should also be discussed based on the XRD peak shifts.
3. Table 1, the isothermals and pore size distribution diagrams of different samples need to be provided along with the BET data summarized in Table 1.
4. Figure 3, and figure 4, the authors should tried to relate the experimental data of TPD-CO2 and the TGA-DTA analysis, especially on the peak temperatures.
5. The phrase “producing fatty acid methyl ester (FAME)” appears several times throughout the manuscript, an abbreviation can be used after its first appearance.

Author Response

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Reviewer 2 Report

Review of the article "K2O doped dolomite as heterogeneous catalyst for fatty acid methyl ester production from palm oil".
The article has been written carefully with the clearly defined aim. In my opinion the presented results are very valuable.
After English correction by a native speaker including removal of typographical errors, the article can be published in Catalysts.

Author Response

Thank you for your kind comments for our manuscript.

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Reviewer 3 Report

Dear Authors,

The manuscript requires additions and corrections.

1. A scientific thesis has to be put forward clearly in the paper, the thesis must be then confirmed (or denied) by research .
2. Figure 4. :

• there are no markings a, b, c, d, e in the drawing,
• drawing should be discussed in more detail.

3. The mechanism of the tested catalyst in the transesterification reaction is not presented in the paper. 

4. Materials and Methods chapter:

• The characteristics - composition of the dolomite used were not presented. Depending on the period of formation, dolomites have different physical and chemical properties. (main groups of dolomites are: primary dolomites, diagenetic dolomites, epigenetic dolomites). That is why giving the composition is very important.
• Verse 333 - 335: cit. „For a 5 wt%K/D K₂O loadings, 3.6 g of K₂CO₃ was dissolved in 50 ml of deionized water. While 10 wt%K/D, 15 wt%K/D and 20 wt%K/D loadings require 7.3 g, 11.0 g and 14.6g of K₂CO₃ respectively.” There is a mistake. If 5 wt%K/D loadings 3.6 g of K₂CO₃, then 10 wt%K/D loadings 7.2 g of K₂CO₃, 20 wt%K/D loadings 14.4 of K₂CO₃.
• Transesterification:                                                                                                                                                                                                       please explain why the transesterification time was 1h?                                                                                                                                                          a reaction time (phase contact) impact study should be performer,                                                                                                                                        stand for the transesterification palm oil process diagram is missing.

⦁ Verse 372 - 374: quotation „The number of fatty acids methyl ester produced by transesterification reaction was investigated by gas chromatography flame ionization detector GC–FID.” The type of chromatographic column used and the temperature program must be provided.

Author Response

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