Abstract
Bimetallic cobalt–molybdenum oxide (CoMoO
x
) has been prepared and converted into CoMoN
x
, CoMoC
x
and CoMoS
x
materials by temperature-programmed reactions with ammonia, ethane or hydrogen sulfide, respectively. These new bimetallic materials have been characterised using X-ray diffraction (XRD) and solid state NMR and tested for pyridine hydrodenitrogenation (HDN) at various temperatures. The initial HDN activity of the catalysts decreases in order CoMoC
x
∼
CoMoN
x
∼
CoMoO
x
>
CoMoS
x
. The stability order of the first three of catalysts is CoMoC
x
>
CoMoN
x
>
CoMoO
x
, and their activities decrease with the time on stream. In contrast the pyridine conversion over CoMoS
x
is more stable and activity increases with the time on stream, from 30 to over 50%, this is accompanied by the formation of CoMoSC
x
material. The high catalytic activity of the CoMoC
x
catalyst may reflect the ability to hydrocrack pyridine to yield methane. The CoMoS
x
catalyst system has the highest selectivity to the products cyclopentane (35%) and pentane (27%).
A comparison between Co
4Mo
6 catalysts in carbide, nitride, sulfide, and oxide forms was studied for HDN of pyridine. The activities of these catalysts at steady state are shown in the order of: CoMoC
x
>
CoMoN
x
>
CoMoS
x
>
CoMoO
x
.
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