Fabrication of Monolithic Catalysts: Comparison of the Traditional and the Novel Green Methods

Round 1

Reviewer 1 Report

The manuscript entitled »Synthesis of Monolithic Catalysts: Comparison between Traditional and Novel Green Methods« is a review in which the authors compare the methods of synthesis of monolithic catalysts. The topic taken up in the presented manuscript seems to be a good idea for an article. However, in my opinion, the scientific quality of offered paper is very low. The cited results are poorly described, without providing crucial points. For instance, the authors give the information about the catalytic activity of some catalysts obtained with one of the methods without comparing it with activity of this catalysts obtained with other methods. There is also the fragment with comparison of the activity but without telling for each reaction: “Xiao et al.[56] assembled nanoflower-like Co₃O₄/Ni-foam by electro-deposition method with cobalt nitrate as the only reagent. The deposition time varied from 300 to 3600 s. The monolithic catalysts had plenty of pores, which exposed more active cobalt sites and provided no limitations for the diffusion of reactant and products. The results showed that the catalytic activity per gram of Co₃O₄ at 220 °C for the Co-Ni-300s was almost 3 times higher than that of powder Co₃O₄.” So there is often no background to be able to judge the quality of the results. The authors show nearly no characterization of the catalysts they are concerning. There is just one Figure (Fig. 4) showing the SEM images for Al/Al₂O₃+Co/Co system. The review should show a lot of examples to illustrate the complex description of the subject it has undertaken. This manuscript seems to be more like the student essay than scientific paper. As I mentioned before, the idea is good but the realization is not acceptable. Moreover, the manuscript contains a lot of grammatical mistakes as well as substantive errors.

Author Response

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Reviewer 2 Report

This work is interesting and well structured. The language should be improved:

l. 70 Ni species were finely

l- 74 after supporting a thin layer

79 fibers as a raw

81 not only facilitated

82 ratio

92 as a carrier as an active

93 combustion under simulated

98 while they have

107 a low specific

115 Al2O3 as a precursor

120 put reaciton conditions

135 deactivation 

137 and the activity 

140 a secondary

142 in the presence 153 Inconclusions 

154 further increase

164 high dispersion

172 the active species

175 finally transforms to active species

194 catalysts increased in the following order:

198 dipping produced Pd and PdO

207 That makes whole impregnaiton method complicated

208 It consumes a lot of energy too, since there are two calcinations steps

Toxic gases will 

214 catalyst were added into

218 alloy

219 methods

220 of a binder

221 ball-milling

225 the preparation 

226 the prepared catalysts

the catalyst prepared..

240 were more active

261 repeated

265 dispersion liquid was prepared

270 group synthesized

279 different supports

281 respraying the liquid 

294 Hydrothermal method as a conventional one to ..

297 homogeneous

317 calcined

416 solution exhibited high cost 

in titles e,g, 3.2. Electrodepositing

large font

 

Author Response

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Reviewer 3 Report

This review manuscript deals with the preparation of monolithic catalysts to give a detailed comparison of their traditional and novel green fabrication methods. Since the heterogeneous catalysis have high impact on the environmentally friendly processes, this overview can be meaningful for the future developments on this field.

In this form, however, this manuscript cannot be published for the following reasons:

1) p. 1 lines 2–3  The authors should modify the title, because the actual one is slightly not precise. My suggestion is the following: Fabrication of Monolithic Catalysts: Comparison of the Traditional and the Novel Green Methods.

2) p. 3 line 122  It is difficult to read the Figure 1 due to its small size, but this is a general problem with all figures. You should increase their extents. Furthermore, in this figure, the authors should add more legends directly into the drawings. For example, you should give in the picture that the blue circle is “γ-Al₂O₃”.

3) p. 4 line 161–170  The subsection “2.1.3. active species” is a relatively short part of the manuscript. The authors should give more details about the role of the catalytically active metals and should specify their names and the reactions where the described effects were observed. Furthermore, you should move the last sentence into the next section or should be deleted, because it does not logically belong to this part.

4) ps. 10–13 Style of the references does not meet the requirements of journal CATALYSTS. For example, in case of “Applied Catalysis B: Environmental.” you should use its abbreviated form: Appl. Catal. B: Environ. Practically, the all references 1–59 contain some mistakes. Please, check and modify them carefully.

5) The English also needs improvements. There are some, typical mistakes:

p. 1 line 12 „… because of low pressure drop, high mass and heat transfer efficiency and poor recyclability.”  instead of  due to the low pressure drop, the high mass and heat transfer efficiency and the poor recyclability of the latter ones.

       line 15 and elsewhere „… hydro-thermal and electro-deposition …”  instead of  hydrothermal and electrodeposition

       line 39  „What is more, …”  instead of  Moreover,

p. 2 line 58 „… monolithic carriers” instead of  Monolithic carriers

       line 71 „… couldn’t …”  instead of  could not

       line 85 „… [19],[20] …”  instead of  [19,20]

p. 3 line 94 „… particles-like…” instead of  particle-like

       line 104 „… complicated, So …”  instead of  complicated, so

       line 106 „… secondary layer”  instead of  Secondary layer formation

p. 4 line 145 „… Pd/Cordierite (Pd/Cor) and Pd/Graphene/Cordierite…” instead of Pd/cordierite (Pd/Cor) and Pd/graphene/cordierite

        line 150 „… grapheme …”  instead of  graphene

        line 161 „… active species”  instead of  Active species

        line 175 „Sometimes a prepared monolithic catalyst needs 3~7 cycles like this[22].”  instead of  ??

        line 179 „… “light-off” temperatures (T₁₀) …”  instead of  “light-off” temperatures (T_lo)

p. 5 line 202 „And some monolithic catalysts did obtain by impregnation method.” instead of  And some monolithic catalysts could be obtained by impregnation method.

       line 214 “This method added the precursors or the ready-made powder catalyst into the slurry of secondary layer directly.”  instead of  Using this method, the precursors or the ready-made powder catalysts were added into the slurry of secondary layer directly.

p. 6 line 236 and elsewhere „… o-xylene …” instead of o-xylene

       line 237 „… dissoved …”  instead of  dissolved

       line 248 „Fig 2 showed …”  instead of  Fig. 2 shows

p. 7 line 308 „3. novel synthesis” instead of  3. Novel preparation methods

       line 293 „… hydrothermal”  instead of  Hydrothermal process

p. 8 line 309 „Thanks to …” instead of Due to

       line 320 „… SCR performance.”  instead of  Please, resolve the abbreviation SCR!

       line 326 „… five times than that of …”  instead of  five times higher than that of

       line 330 „Because MnO₂-Co₃O₄ monolithic catalyst had a synergistic effect between manganese and cobalt, and the Mn–O bonds became weaker, thus more surface oxygen species improved redox property.…”  instead of  Since the MnO₂–Co₃O₄ monolithic catalyst had a synergistic effect between manganese and cobalt, and the Mn–O bonds became weaker, the more surface oxygen species improved redox property.

       line 349 „… electrodepositing”  instead of  Electrodepositing

p. 9 line 362 „… Fig 4 described …” instead of  Fig. 4 depicts

p. 10 line 406 „… Repeatedly cycles…” instead of  Repeated cycles

         line 430 „… environment-friendly …”  instead of  environmentally friendly

Author Response

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Round 2

Reviewer 1 Report

The manuscript entitled »Fabrication of Monolithic Catalysts: Comparison of the Traditional and the Novel Green Methods« has been strongly updated. In my opinion, the present form of the manuscript is acceptable for publication in Catalysts, however the following points should be addressed:

The titles of the subsections of section 2 should be improved. For example:

2.“Traditional preparation methods”

The first paragraph (2.1) do not need the number.

The number 2.1 should be for the paragraph describing the monolithic carriers, as follow:

2.1. Monolithic carriers

2.2 Secondary layer formation

2.3. Active phase deposition

2.3.1. Impregnation method

2.3.2. Coating method

2.3.3. Spraying method

And then beginning from section 3, as it is.

 

In Figure 1 the circle that represents Al₂O₃ seems to be more purple than blue. It should be improved.

Author Response

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