(470c) Dry Reforming of Methane over Ni-Based Pyrochlore Catalysts Using Transient Pulsing
Dry reforming of methane requires temperatures of 750 – 950 °C to achieve near equilibrium conversions. A thermally robust and active catalyst, such as Ni-substituted La2Zr2O7 pyrochlore is desirable to achieve long term synthesis gas production.
Here, we report pulsing experiments in which 10% CH4/He flows over a pre-reduced catalyst continuously while pulses of 10% CO2/He was switched with pure helium gas. The products were quantified using an in-line quadrupole mass spectrometer.
The results at 750 °C show the deactivation of the catalyst during the first pulse, but in the subsequent pulses the catalyst is found to be stable. At 800 °C and 850 °C, the CO concentration decreases during each CO2 pulse. However, the catalyst activity was found to be increasing from its initial value before start of each pulse, which corresponds to an increase in the reaction rate of the CO2-consuming reaction(s). Carbon, formed during the times only CH4 flows, reacts with CO2 to produce CO. At the higher temperatures, the reaction is faster, producing more CO and consuming the carbon faster.