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

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

Hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + various amounts of CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 0–400 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K, 4 h. 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
getmorefigures.php?uid=PMC5036504&req=5

Figure 2: Hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + various amounts of CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 0–400 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K, 4 h. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.

Mentions: The effect of amount of CeO2 additive on the catalysis is shown in figure 2. The activity was increased with increasing CeO2 amount; however, too much amount of CeO2 decreased the selectivity to CyCH2NH2 and increased the selectivity to unknown by-products. 50–100 mg of CeO2 was the best amount as additive to Rh–MoOx/SiO2, and we used 100 mg of CeO2 in the other parts of this study.


Combination of supported bimetallic rhodium – molybdenum catalyst and cerium oxide for hydrogenation of amide
Hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + various amounts of CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 0–400 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K, 4 h. 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 2: Hydrogenation of cyclohexanecarboxamide (CyCONH2) over Rh–MoOx/SiO2 + various amounts of CeO2. Reaction conditions: Rh–MoOx/SiO2 (Rh 4 wt%, Mo/Rh = 1) 100 mg, CeO2 (uncalcined) 0–400 mg, 1,2-dimethoxyethane 20 g, H2 8 MPa, 413 K, 4 h. Cy = cyclohexyl. ‘Others’ comprise unknown solid products leading to loss of carbon balance during catalysis.
Mentions: The effect of amount of CeO2 additive on the catalysis is shown in figure 2. The activity was increased with increasing CeO2 amount; however, too much amount of CeO2 decreased the selectivity to CyCH2NH2 and increased the selectivity to unknown by-products. 50–100 mg of CeO2 was the best amount as additive to Rh–MoOx/SiO2, and we used 100 mg of CeO2 in the other parts of this study.

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