An Experimental Approach on Industrial Pd-Ag Supported α-Al₂O₃ Catalyst Used in Acetylene Hydrogenation Process: Mechanism, Kinetic and Catalyst Decay

Round 1

Reviewer 1 Report

This manuscript deals with the hydrogenation of acetylene in ethylene flows under realistic experimental conditions. A theoretical framework is also provided, which explains (and also predicts) catalyst deactivation and possible solutions. The use of in-plant real data combined with laboratory data, is remarkable. I suggest publication. Just some issues to be addressed:

- The "spent" catalyst is analyzed by a couple of techniques, and not all those shown for the fresh catalyst. Full comparison will be of interest.

- Minimum acceptable specifications for the final flow (ppms of acetylene, maximum % of ethane, amount of butenes,...) is not mentioned.

- Is Ag alloyed with Pd or they act separately?

- Non-noble metals start to be studied as possible catalyst alternatives. See and cite if appropriate J. Am. Chem. Soc. 2018, 140, 8827−8832.

- Please revise grammar and some typos (i.e. Table 1 and 2 captions: "The...)

Author Response

Point 1:  The "spent" catalyst is analyzed by a couple of techniques, and not all those shown for the fresh catalyst. Full comparison will be of interest.

Response 1: Thanks for your useful comment. The SEM, TEM and TGA results and particle size distribution of fresh and spent catalysts have been presented in results and discussion section. Based on your comment, The BET results of the fresh and catalyst were presented in Table 4 to improve the quality of the paper as:

Table 4, the BET results of fresh and spent catalysts

Point 2:  Minimum acceptable specifications for the final flow (ppms of acetylene, maximum % of ethane, amount of butenes) is not mentioned.

Response 2: Generally, the maximum allowable limit of acetylene is 5 ppm in the outlet stream from acetylene hydrogenation. Although, there is not any limit for concentration of ethane and butene groups, the minimum ethylene purity in polymerization processes is about 99.90 %. Based on your comment the introduction was revised as:

“Typically, the minimum required purity of ethylene in the polymerization processes to produce polyethylene is about 99.90 % and the maximum allowable limit of acetylene is 5 ppm known as polymer-grade ethylene”

Point 3:  Is Ag alloyed with Pd or they act separately?

Response 3: The considered catalyst was prepared by impregnation method and Pd and Ag dispersed on the catalyst separately. Based on your comment the Experimental Method section was revised as:

“The catalyst is prepared by impregnation method and Pd and Ag are dispersed on the catalyst separately.”

Point 4:  Non-noble metals start to be studied as possible catalyst alternatives. See and cite if appropriate J. Am. Chem. Soc. 2018, 140, 8827−8832.

Response 4: Thanks for your useful comment. The Introduction section was revised as:

“Currently, the use of non–toxic and inexpensive metals such as Fe, Ti, Cu or Zr, instead of Pd and Ag based commercial catalysts is an attractive topic. In this regard, Serrano et al, focused on the embedding FeIII on an MOF to prepare an efficient catalyst for hydrogenation of acetylene under front–end conditions [18]. The experimental results showed that the prepared catalyst presents similar activity to Pd catalyst and could control acetylene concentration at the desired level.”

Point 5:  Please revise grammar and some typos (i.e. Table 1 and 2 captions: "The...)

Response 4: Thanks for your comment, it was considered and manuscript was revised carefully. 

Reviewer 2 Report

The manuscript " An Experimental Approach on Industrial Pd-Ag  Supported α-Al2O3 Catalyst Used in Acetylene  Hydrogenation Process: Mechanism, Kinetic and Catalyst Decay" describes the practical approach on Pd-Ag based hydrogenation catalyst. The results and conclusions are well supported by characterization inferences as well as proposed kinetic model. I recommend the publication of manuscript.

Author Response

Thanks for your positive response.