Pyrolysis Products Distribution of Enzymatic Hydrolysis Lignin with/without Steam Explosion Treatment by Py-GC/MS

Round 1

Reviewer 1 Report

In my opinion, the reviewed article contains a lot of interesting information about the transformation of lignin during pyrolysis.

I have only minor comments on the manuscript:

1) In the introduction: it seems reasonable to add a justification why pyrolysis is a promising method for processing lignin

2) The FTIR analysis methodology is not described

3) on line 219 instead of DH;-SE should be DHL-SE.

Author Response

Dear Editors:

We have revised the manuscript according to reviewers' comments. In our point-by-point response attached below, reviewer comment is in larger fonts (12 pt) and our response is in smaller fonts (10 pt).

We look forward to hearing from you. Thank you.

Note: In order to highlight the changes what we have done, the color of text changed will become yellow.

Following are our response about reviewers' comments to our manuscript catalysts-708382:

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Reviewer 1:

In my opinion, the reviewed article contains a lot of interesting information about the transformation of lignin during pyrolysis.

I have only minor comments on the manuscript:

1) In the introduction: it seems reasonable to add a justification why pyrolysis is a promising method for processing lignin

Answer: Revised. We added in the introduction: As one of the promising thermal approaches, pyrolysis could be applied to convert cheap, local, and abundant lignocellulosic biomass into energy.9 It plays an important role in the thermochemical conversion of biomass to bioenergy.

2) The FTIR analysis methodology is not described

Answer: Revised. We added in Part 2.3: Fourier transform infrared (FTIR) spectra were recorded by a Nicolet 6700 FTIR spectrometer under the resolution of 1 cm-1 in 32 scans by a KBr disk with the wavenumber ranging from 4000 to 500 cm-1.

3) on line 219 instead of DH;-SE should be DHL-SE.

Answer: Revised.

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Thanks for your reviewers’ excellent comments and advices!

Sincerely yours,

Xiaoli Gu *

Author Response File: Author Response.pdf

Reviewer 2 Report

This work reports the pyrolytic behaviors of enzymatic hydrolysis lignin (EHL) and EHL treated by steam explosion (EHL-SE) by pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS). 2-methoxy-4-vinylphenol with 11% relative content was the most predominant pyrolytic product from lignin after steam explosion treatment. This work can be published after adequate revision.

Is there any possibility for the formation of dimers and oligomers during pyrolysis of lignin?

Authors should comment on the formation of coke and tar during pyrolysis of lignin.

Line 142, authors reported the presence of carbohydrate derivatives, such as cellulose and hemicellulose in the enzymatic hydrolysis lignin. Can authors comment on the percentage of these carbohydrates?

Typo errors

Line 37, guaiac

Line 174, 3-cyclopentadiene

Line 221, phenol are

Author Response

Dear Editors:

We have revised the manuscript according to reviewers' comments. In our point-by-point response attached below, reviewer comment is in larger fonts (12 pt) and our response is in smaller fonts (10 pt).

We look forward to hearing from you. Thank you.

Note: In order to highlight the changes what we have done, the color of text changed will become yellow.

Following are our response about reviewers' comments to our manuscript catalysts-708382:

------------------------------------------------------

Reviewer 2:

This work reports the pyrolytic behaviors of enzymatic hydrolysis lignin (EHL) and EHL treated by steam explosion (EHL-SE) by pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS). 2-methoxy-4-vinylphenol with 11% relative content was the most predominant pyrolytic product from lignin after steam explosion treatment. This work can be published after adequate revision.

Is there any possibility for the formation of dimers and oligomers during pyrolysis of lignin?

Answer: Right. It’s possible for the formation of dimers, trimers and oligomers during pyrolysis of lignin. But it might be not detected by GC/MS because of its higher boil point. We will further our research about it. Thanks.

Authors should comment on the formation of coke and tar during pyrolysis of lignin.

Answer: In this paper, we focus on bio-oil products distribution during lignin pyrolysis. In our next paper, we will investigate the formation of gas, bio-oil, and coke/tar during lignin conversion. Thanks for your suggestion.

Line 142, authors reported the presence of carbohydrate derivatives, such as cellulose and hemicellulose in the enzymatic hydrolysis lignin. Can authors comment on the percentage of these carbohydrates?

Answer: Revised. We added in Line148: (about 5 wt% -10 wt%).²⁹

(29)  Consolación Á.; Francisco M. R.; Bruno D., Enzymatic hydrolysis of biomass from wood. Microb Biotechnol. 2016, 9, 149–156.

Type errors

Line 37, guaiac

Answer: Revised. We added ‘guaiacol (G)’.

Line 174, 3-cyclopentadiene

Answer: Revised. We added ‘6,6-dimethyl-5-methylene-1,3-cyclopentadiene’.

Line 221, phenol are

Answer: Revised. We added ‘phenolic compounds were main substances’.

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Thanks for your reviewers’ excellent comments and advices!

Sincerely yours,

Xiaoli Gu *

Author Response File: Author Response.pdf