1. Text Correction
In the published article “Vapor-Phase Oxidant-Free Dehydrogenation of 2,3- and 1,4-Butanediol over Cu/SiO2 Catalyst Prepared by Crown-Ether-Assisted Impregnation“ [1], we came to the realization that we made a mistake in calculating the Cu dispersion, D. Considering that the calculation of Cu surface area, SACu, and the mean particle size of Cu, DCu, are derived from D, this mistake also affected the values of SACu and DCu. The correct D and SACu values should have been twice the values listed in the original publication, whereas the DCu should have been half the values listed in the original publication. It should be noted that the corrections do not change the main finding and conclusion of the research work. This correction was solely done to ensure the transparency, objectivity, and reproducibility of the research work. Following this mistake, several tables and figures need to be revised, and the revisions are as follows.
The description in Section 3.6 must also be revised since there was information related to SACu. The corrected description of Section 3.6 is as follows:
“Figure 7c depicts the relation between SACu and the formation rate of GBL in the dehydrogenation of 1,4-BDO at 240 °C. The GBL formation rate is proportional to the SACu for SACu values smaller than 30 m2 g−1, while the proportional relation was not observed for SACu values higher than 30 m2 g−1. This phenomenon differed from the results in the dehydrogenation of 2,3-BDO to AC, in which the AC formation rate was proportional to SACu, even for SACu values higher than 30 m2 g−1. This difference can be explained by the mechanism of 1,4-BDO dehydrogenation to GBL. The dehydrogenation of 2,3-BDO to AC is a straightforward reaction, whereas 1,4-BDO dehydrogenation to GBL proceeds via a series of consecutive reactions, including (1) the dehydrogenation of 1,4-BDO to 4-hydroxybutanal, (2) the intramolecular hemiacetal-formed cyclization to 2-hydroxytetrahydrofuran, and (3) the dehydrogenation of 2-hydroxytetrahydrofuran to form GBL (Scheme 2) [41]. The cyclization via an intramolecular hemiacetal reaction was possibly catalyzed by the acid sites of the silanol group in a similar manner to the cyclization of levulinic acid to angelica lactone [71]. Similarly, acidic alumina-supported Cu was also effective for the cyclization of 4-hydroxybutanal; nevertheless, the strong acidity of alumina promoted the dehydration reaction, generating tetrahydrofuran as the side product [41]. For SACu values below 30 m2 g−1, the increment of Cu content did not significantly alter the concentration of silanol sites; thus, the increment of Cu content favored the dehydrogenation of 1,4-BDO to 4-hydroxybutanal but did not hinder the consecutive cyclization of 4-hydroxybutanal to 2-hydroxytetrahydrofuran. However, when the SACu was higher than 30 m2 g−1, the increment of Cu content decreased the contribution of OH to the level that it slightly hindered the cyclization of 4-hydroxybutanal to 2-hydroxytetrahydrofuran and the subsequent GBL formation. As a result, a proportional relation between SACu and GBL formation rate was no longer observed for SACu values above 30 m2 g−1, as shown in Figure 7c.”
2. Error in Table
The D and SACu values are displayed in Table 1; as a result, Table 1 should be corrected as follows:
Table 1.
Effect of organic additive on the catalytic performance of 2Cu/SiO2 catalyst in the dehydrogenation of 2,3-BDO.
Table 1.
Effect of organic additive on the catalytic performance of 2Cu/SiO2 catalyst in the dehydrogenation of 2,3-BDO.
| Entry | Organic Additive | D | SACu /m2 g−1 | Conversion a /mol% | Selectivity a/mol% | |
|---|---|---|---|---|---|---|
| AC | DA | |||||
| 1 | none | 0.248 | 2.76 | 19.0 | 99.3 | 0.0 |
| 2 | 12C4 | 0.632 | 7.06 | 56.4 | 98.8 | 1.0 |
| 3 | 15C5 | 0.613 | 6.84 | 43.0 | 99.2 | 0.5 |
| 4 | 18C6 | 0.521 | 5.81 | 38.9 | 99.3 | 0.4 |
| 5 | CA | 0.549 | 7.12 | 50.2 | 99.0 | 1.0 |
Reaction conditions: Reaction temperature, 200 °C; W/F, 0.18 h. a Average conversion and selectivity at TOS of 0–1 h.
The information of SACu is also displayed in Table 3; thus, the revised Table 3 is shown below. In the last entry, the SACu of the 12C4-10Cu/SiO2 catalyst has been corrected.
Table 3.
Comparison of the productivity of GBL over various reported Cu catalysts.
Table 3.
Comparison of the productivity of GBL over various reported Cu catalysts.
| Catalyst | SACu /m2 g–1 | Temp. /°C | W/F /h | TOS a /h | Conv. /mol% | Select. /mol% | GBL Prod. /g gcat−1 h−1 | Ref. |
|---|---|---|---|---|---|---|---|---|
| Cu/ZnO/ZrO2/Al2O3 b | 40.3 | 240 | 0.08 | 5 | 84 | 98 | 9.63 | [41] |
| 12Cu/SiO2 | 3.90 | 250 | 0.50 | 10 | 100 | 98 | 1.92 | [17] |
| 10Cu/La2O3/ZrO2 | 8.40 | 250 | 1.00 | 13 | 97 | 96 | 0.91 | [43] |
| 10Cu/SBA-15 | 8.68 | 250 | 1.00 | 17 | 100 | 98 | 0.95 | [44] |
| 10Cu/CeO2 | 5.60 | 240 | 0.50 | 1 | 93 | 98 | 1.78 | [18] |
| 10Cu/CeO2-Al2O3 | - | 240 | 0.50 | 1 | 100 | 99 | 1.94 | [45] |
| 12C4-10Cu/SiO2 | 26.1 | 260 | 0.27 | 5 | 98.8 | 98.5 | 3.44 | This work |
| 0.054 | 5 | 81.4 | 95.7 | 13.8 |
a Time on stream in a flow system. b Prepared by co-precipitation; Cu content, 41.8 wt.-%.
3. Error in Figure
The values of SACu were also displayed in Figure 5b and Figure 7c; therefore, those figures should be revised as follows:
Figure 5.
(b) Effect of SACu on the formation rate of AC at 200 °C.
Figure 7.
(c) Relation between Cu surface area and the formation rate of GBL at 240 °C.
The D, SACu, and DCu are also depicted in supporting information. The original Table S2 has also been updated.
The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.
Reference
- Kurniawan, E.; Hosaka, S.; Kobata, M.; Yamada, Y.; Sato, S. Vapor-Phase Oxidant-Free Dehydrogenation of 2,3- and 1,4-Butanediol over Cu/SiO2 Catalyst Prepared by Crown-Ether-Assisted Impregnation. Chemistry 2023, 5, 406–421. [Google Scholar] [CrossRef]
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