Hydrogenation of Furfural to Furfuryl Alcohol over Ru Particles Supported on Mildly Oxidized Biochar

Round 1

Reviewer 1 Report

The work is devoted to the actual topic of Ru-based catalysts design for furfural hydrogenation. The reported results are novel and interesting. The manuscript is well written. I could recommend this manuscript for publication in Catalysts after minor revisions.

Questions:

• Why did authors initially use biochar with low surface area?
• What temperature was used for reaction? What about catalyst particle sizes used for catalytic experiments? It could strongly influence the mass transfer in the system.
• Table 1. Why the BET surface of Ru-OBC was much lower than that of initial OBC?
• Table 1. Why TEM and H2 chemisorption results on Ru dispersion are so different?
• Did authors observe Ru reduction by support material?
• It is not clear how did authors use DFT for clarification of catalysts pore distributions.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Kaliaguine and co-worker reported in this manuscript on the development of Ru particles supported on BC and OBC and their use as catalysts for hydrogentation of furfural to furfuryl alcohol. The synthetic procedures of catalysts are well described and the catalysts are fully characterized. The catalytic activity of the catalyst Ru-OBC was investigated under different conditions including catalyst loading, reaction temperature, reaction time and hydrogen pressure. The comparison of catalyst performance of Ru-OBC with literatures was also investigated and the results showed that the Ru-OBC was amongst the very best catalysts reported. This research work will attract interest from catalyst field. I would recommend it for publication in catalysts

Author Response

We thank this reviewer for his/her kind appreciation of our work.

Reviewer 3 Report

The manuscript of Bardestani et al. reports on a new catalytic possibility to convert furfural to furfuryl alcohol, as a phase of bio-oil conversion to liquid fuel. The topic is of high scientific interest and the authors addressed a new approach of improving biochar as catalyst support by mild oxidation, increasing its adsorption capacity for the active Ru catalyst up to 2.2 wt. %. Although biochar as support and Ru as catalyst were already reported for similar processes, I consider that this manuscript provides a notable scientific and technological improvement in the field, by using a more simple and easily available activation method which leads to enhanced Ru content and better dispersion of the catalyst. I would like to highlight the catalyst characterization part, targeting both the morphological and the structural issues subsequent to the preliminary mild oxidation. In fact, I have rarely seen such a comprehensive and coherent characterization of a supported catalyst as presented in this work. Therefore, I recommend this valuable manuscript for publication, with only one comment and question:

The obtained Ru/OBC catalyst showed good (but not outstanding) performance compared to other catalysts, concerning the furfural conversion and furfuryl alcohol selectivity, as results from Table 3 data. The utilization of water as solvent seems to represent another advantage of this process. However, a possible drawback may be the longer reaction time than reported for other catalysts. Stability is an important characteristic of a heterogeneous catalyst as well, but data related to this property were not provided. Could the authors comment it?

Author Response

We thank this reviewer for his/her kind appreciation of our work.

We believe that a further investigation on the kinetics of the reaction may allow us to optimize the reaction conditions in order to reduce the reaction time.

The reviewer is totally right and catalyst stability is an important characteristic. The principal target of the present work was to increase our understanding to the effects of mild air oxidation on the metal dispersion and the catalyst activity in hydrogenation of aldehyde. Also, due to our time limitation, we did not investigate the stability of the catalyst used in this work.