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Combination of supported bimetallic rhodium – molybdenum catalyst and cerium oxide for hydrogenation of amide

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ABSTRACT

Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6–7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh–MoOx/SiO2, and the addition of CeO2 much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2–8 MPa and 393–433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh–MoOx/SiO2 + CeO2 was 63%. The effect of CeO2 addition was highest when CeO2 was not calcined, and CeO2 calcined at >773 K showed a smaller effect. The use of CeO2 as a support rather decreased the activity in comparison with Rh–MoOx/SiO2. The weakly-basic nature of CeO2 additive can affect the surface structure of Rh–MoOx/SiO2, i.e. reducing the ratio of Mo–OH/Mo–O− sites.

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Time course of hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 100 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.
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Figure 1: Time course of hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 100 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.

Mentions: Figure 1 shows the time course of hydrogenation of CyCONH2 over Rh–MoOx/SiO2 in combination with CeO2. The selectivities were hardly changed until the total conversion of CyCONH2, and then the selectivity to CyCH2NH2 was gradually decreased and that to (CyCH2)2NH was gradually increased. The highest yield of CyCH2NH2 was 63% obtained at 8 h (equation (3)). Although the yield value was lower than that over unsupported Rh/Mo catalyst in the literature (87%), the activity was significantly higher (CyCONH2/Rhtotal = 50 at 413 K, 8 h in this study; CyCONH2/Rhtotal = 20 at 433 K, 16 h in the literature [13]).


Combination of supported bimetallic rhodium – molybdenum catalyst and cerium oxide for hydrogenation of amide
Time course of hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 100 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036504&req=5

Figure 1: Time course of hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 100 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.
Mentions: Figure 1 shows the time course of hydrogenation of CyCONH2 over Rh–MoOx/SiO2 in combination with CeO2. The selectivities were hardly changed until the total conversion of CyCONH2, and then the selectivity to CyCH2NH2 was gradually decreased and that to (CyCH2)2NH was gradually increased. The highest yield of CyCH2NH2 was 63% obtained at 8 h (equation (3)). Although the yield value was lower than that over unsupported Rh/Mo catalyst in the literature (87%), the activity was significantly higher (CyCONH2/Rhtotal = 50 at 413 K, 8 h in this study; CyCONH2/Rhtotal = 20 at 433 K, 16 h in the literature [13]).

View Article: PubMed Central - PubMed

ABSTRACT

Hydrogenation of cyclohexanecarboxamide to aminomethylcyclohexane was conducted with silica-supported bimetallic catalysts composed of noble metal and group 6–7 elements. The combination of rhodium and molybdenum with molar ratio of 1:1 showed the highest activity. The effect of addition of various metal oxides was investigated on the catalysis of Rh–MoOx/SiO2, and the addition of CeO2 much increased the activity and selectivity. Higher hydrogen pressure and higher reaction temperature in the tested range of 2–8 MPa and 393–433 K, respectively, were favorable in view of both activity and selectivity. The highest yield of aminomethylcyclohexane obtained over Rh–MoOx/SiO2 + CeO2 was 63%. The effect of CeO2 addition was highest when CeO2 was not calcined, and CeO2 calcined at >773 K showed a smaller effect. The use of CeO2 as a support rather decreased the activity in comparison with Rh–MoOx/SiO2. The weakly-basic nature of CeO2 additive can affect the surface structure of Rh–MoOx/SiO2, i.e. reducing the ratio of Mo–OH/Mo–O− sites.

No MeSH data available.


Related in: MedlinePlus