Detail Comments I~iii

MS#070602

by Reviewer I

Detail Comments: This work describes some of the variables employed in the production of hydrogen and longer hydrocarbons from methane using dielectric barrier discharge barrier in both non catalytic and catalytic (Cr/Zn) operation modes. It reads easily, data appear analyzed in some detail, although its innovation is limited. Several issues summarized below must be addressed. •

The temperature of the catalytic bed should be reported. In the absence of this is difficult, if not impossible to explain any change in both methane conversion and product selectivity.

•

Methane decomposition under DBD conditions is not a selective process since many radical reactions are taking place simultaneously. An attempt should be made to rationalise the rates of formation of individual products in terms of the radical concentration and specific reaction rates for individual reaction.

•

A critical issue in this process is the quantification of the amount of carbon formed. A mass balance, including the unknown products, should be made. A simple balance: C deposited = C inlet – C outlet will provide an idea on the extent of carbon deposited.

•

There are several sentences and words along the text to be clarified. As probably English is not the mother language of author, revision by a native speaker is also recommended.

Once these points should be addressed it can be recommended for publication in the journal.

MS#070602

by Reviewer II

Detail Comments: The manuscript should be revised before being published according to the following questions and comments: 1. The applied power was given in W in the text (page 7) while it was in kW in Figure 1. Please correct it. 2. The word “reused” should be replaced by either “regenerated” or “reactivated’. It is very hard to follow the text in page 11 and Figures 6a and 6b. 3. Figure 3b is very hard to see because the similar shades were used. 4. Figure 6 did not specify the studied conditions. Please add the studied conditions in the figure. 5. Please explain how the catalyst was only able to enhance the hydrogen selectivity. 6. Please explain why the activity of the catalyst was almost zero after the third cycle in use. 7. It will be better to compare the energy consumption at different residence times and with and without catalyst. It is strongly recommended that the manuscript is needed to improve the English. There are several grammatical errors.

MS#070602

by Reviewer III

Detail Comments: The paper was studied in hydrogen production form methane in a dielectric barrier discharge using oxide zinc and chromium as catalyst. The author used the plasma method to produce hydrogen. The advantages of this method are short operating time and (may ) low cost. However, the hydrogen production from methane in the literature is well-known higher than 70%. The concentration is below than 40%. That is, the hydrogen is not main product in this process. On the other hand, the hydrogen production was only enhanced 10% in the presence of oxide zinc and chromium as catalyst. Which role did the catalyst play in this system? How to improve their system to allow hydrogen to become a main product did not show in the text by the author. Hence, the objective of this paper is low. Therefore, I don’t recommend it to publish in this Journal.