Enhanced Cyclopentanone Yield from Furfural Hydrogenation: Promotional Effect of Surface Silanols on Ni-Cu/m-Silica Catalyst
, Putrakumar Balla 5, Xiaoqiang Zhang 1,2,3, Kishore Ramineni 6, Hong Du 1,2,3, Shrutika Lingalwar 4, Vijayanand Perupogu 4 and Zongchao Conrad Zhang 1,2,*
Round 1
Reviewer 1 Report
Balaga et al. investigated bimetallic Ni and Cu on mesoporous silica (m-SiO2) as catalysts for the hydrogenation of furfural (FAL) to cyclopentanone (CPO). The study describes various characterization techniques to understand the structural relation with catalytic activity. In addition, the effect of silanol groups in the FOL rearrangement was studied in detail. The reported work is interesting, well written and can be considered for publication after the authors address the following issues:
1. Line 99 “Ni20 on m-SiO2 did not show any peak corresponding to the NiO phase”.
Include the JCPDS XRD pattern corresponding to NiO in the SI.
2. Fig 6a: Ni XPS is not well resolved/deconvoluted. Also, need to include details regarding software used for peak fitting and deconvolution in the Experimental studies.
3. Fig 7: Authors need to describe in the figure caption that X and S stand for conversion and selectivity.
4. Fig 7: It is a suggestion to convert the bar graph into a line plot (with markers) and to split the plot into 2. The first plot focuses on conversion and selectivity to CPO and the second plot highlights the other details.
5. For the leaching test, did the authors perform ICP on the reaction solution? Under high temperature and H2 pressure, the support can disintegrate resulting in higher/similar metallic content to fresh catalyst.
6. The authors have mentioned the importance of silanol for the rearrangement step. Did the authors quantify the silanol content in the catalyst? How does it change with the addition of bimetals?
Author Response
See attached.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript entitled “Enhanced cyclopentanone yield from furfural hydrogenation promotional effect of surface silanols on NiCu/silica catalyst” by R. Balaga et. al. prepared the mono and bimetallic Ni and Cu on mesoporous silica (m-SiO2) catalysts for the hydrogenation of furfural (FAL) to cyclopentanone (CPO) by a direct alkaline hydrothermal method. The catalysts were fully characterized by various techniques and the catalytic activities for CPO production reached the maximum yield at 89.6% with 100% FAL conversion. The results are very interested and I recommended to purplish this manuscript to catalysts MPDI after minor revisions. Here are my comments.
1. The catalytic performance in furfural (FAL) hydrogenation in Figure 7 for the NixCuy/m-SiO2 catalysts at different Ni and Cu compositions was evaluated at 100% conversion. I recommended the author to compare the catalytic activity at lower conversion for three catalysts to confirm the superiority of the catalysts.
2. Cu LMM should be investigated to distinguish the Cu0, Cu1+, and Cu2+ species since the roles of each component significantly affected the catalytic activity for FAL hydrogenation.
3. The details for the experiment of XPS analysis did not provide in the experimental section. Which forms (reduced or calcined ones) of catalysts used to investigate by XPS analysis? Why the metallic Ni species did not detect, whereas, the metallic Cu species was observed in XPS spectrum.
4. In Scheme 1, Did the author detect the 4-HCP, 2-MF, MTHF, and PeD in liquid product?. If could not detect, the possible reaction pathway lacks of evident.
5. Recycled catalyst test was investigated at 100% conversion. it is well known that the comparison of catalytic data at full conversion values can mask deactivation processes, and experimental conditions must be chosen in such a way that conversion values should be much lower.
6. The furfural conversion via direct H2 and CTH should be cited as follows:
https://doi.org/10.1016/j.fuproc.2022.107256
https://doi.org/10.1016/j.biombioe.2021.106033
Author Response
See attached.
Author Response File: Author Response.pdf
Reviewer 3 Report
The hydrogenation of furfural to cyclopentanone was investigated over SiO2 supported mono and bimetallic Ni and Cu catalysts. Ni-Cu alloy on silica obtained by in-situ direct alkaline hydrothermal method shows excellent catalytic performance. The catalysts have been well characterized and the enhanced reasons were also discussed. However, revisions are still needed before published. The details are as following:
1) Quantitative analysis of acidity is needed since it plays an important role in selectivity. Considering the reaction takes place in the aqueous solution, the measurement is better to be carried out in liquid phase (e.g. Catal. Commun. 9 (2008) 769; Bioresource Technology 101 (2010) 7224–7230).
2) Some mistakes should have been revised, e.g. Line 127, Table 1, “No.2, Ni5Cu15/m-SiO2”; Line 172, “Ni5Cu15/m-SiO2 (e, d)”; Line 176, “show t particles”; Line 305, “d due to”.
Author Response
See attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The manuscript can be published after revision.
