Evaluation Of Plasma-Derived Heat And Synergistic Effect For In-Plasma Catalytic Steam Reforming Of Methanol

How to evaluate plasma-derived heat (PDH) and the synergistic effect of plasma catalysis, especially for in-plasma catalysis (IPC), is still ambiguous. In this work, to exclude the reaction-heat impact on PDH, N-2 plasma was first used to compare the heat-uninsulated and heat-insulated cases for empty and packed dielectric barrier discharge (DBD). Compared with the heat-uninsulated cases, the heat-insulation has nearly the same discharge characteristics, and a weak impact on N-2 rotational temperature. The heat-insulation, whether for empty or packed DBD, gave much higher outgoing gas temperature (T-g) and reactor wall temperature (T-w) than the heat uninsulation. For methanol-steam reforming in the heat-insulated reactor over various supported catalysts on Al2O3 support (AS), the dependence of PDH indicated by T-w on reaction-heat power was observed. The synergistic effect of plasma and Au/CeZn/AS catalyst in the heat-insulated IPC reactor was verified. For the plasma alone case, methanol conversion was negligible, giving a T-w of 618 K. For the IPC case, the T-w decreased considerably to 545 K due to the effect of reaction-heat power on PDH. Methanol conversion of 46.8% was achieved, which is much higher than the catalysis alone case of 9.0%, even at a higher temperature of 573 K. Moreover, H-2 selectivity increased from plasma alone from 80.0% to 95.1%. If the IPC case was heat-uninsulated, the T-w dropped down to 385 K, and accordingly methanol conversion became insignificant. This work demonstrated that heat-insulation is necessary for reliable evaluation of the PDH and the synergistic effect in plasma catalysis.