Synthesis of Niobium Carbonitride by Thermal Decomposition of Guanidine Oxaloniobate and Its Application to the Hydrodesulfurization of Dibenzothiophene
A production method that uses lower temperatures than the temperatures of commonly utilized methods (950–1,100 °C) is proposed for the synthesis of niobium carbonitride and niobium carbide. This methodology consists of three stages: (i) the synthesis of guanidine oxaloniobate via a solid-state react...
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Published in | Topics in catalysis Vol. 55; no. 14-15; pp. 910 - 921 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Boston
Springer US
01.10.2012
|
Subjects | |
Online Access | Get full text |
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Summary: | A production method that uses lower temperatures than the temperatures of commonly utilized methods (950–1,100 °C) is proposed for the synthesis of niobium carbonitride and niobium carbide. This methodology consists of three stages: (i) the synthesis of guanidine oxaloniobate via a solid-state reaction at 150 °C between monohydrated ammonium oxotris(oxalate)niobate (niobium ammoniacal complex) and guanidine carbonate; (ii) the thermal decomposition of the guanidine oxaloniobate at 400 °C under an inert atmosphere; and (iii) the subsequent decomposition under an inert atmosphere at temperatures varied between 450 and 900 °C. The structure of the guanidine oxaloniobate was also calculated by density functional theory. The characterization results suggest that at a decomposition temperature of 700 °C, niobium carbonitride (NbC
x
N
1−
x
,
x
< 1) was formed, which was transformed into NbC at higher temperatures (≥850 °C). From the X-ray refinement results, which were performed using the Rietveld method, the formation of NbC was proposed to occur in stages: oxaloniobate → oxynitride → carbonitride → carbide. The materials synthesized at 600, 650 and 700 °C exhibited steady state activities for more than 24 h in the hydrodesulfurization of dibenzothiophene, which predominantly occurred via the direct desulfurization route. |
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ISSN: | 1022-5528 1572-9028 |
DOI: | 10.1007/s11244-012-9876-1 |