Role of Electric Field and Surface Protonics on Low-Temperature Catalytic Dry Reforming of Methane

Abstract

The role of the electric field and surface protonics on low temperature catalytic dry reforming of methane was investigated over 1 wt % Ni/10 mol %La-ZrO 2 catalyst, which shows very high catalytic activity even at temperatures as low as 473 K. We investigated kinetic analyses using isotope and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and kinetic analyses revealed synergetic effects between the catalytic reaction and the electric field with less than one-fifth the apparent activation energy at low reaction temperatures. Results of kinetic investigations using isotopes such as CD 4 and 18 O 2 , in situ DRIFTS in the electric field, and density functional theory calculation indicate that methane dry reforming proceeds well by virtue of surface protonics. CH 4 and CO 2 were activated by proton collision at the Ni−La-ZrO 2 interface based on the "inverse" kinetic isotope effect.

Elucidation of the reaction mechanism on dry reforming of methane in an electric field by in situ DRIFTs

“…71,74 DFT calculations and various experimentally obtained results revealed that lattice oxygen defects enhance the adsorption of gas-phase CO 2 . [75][76][77] Lattice oxygen in the catalyst support dissociates CH 4 in the DRM reaction, leading to the formation of oxygen vacancies. 75,78,79 Consequently, the reaction of CH 4 with lattice oxygen is expected to be an important factor supporting oxygen vacancy formation.…”

Enhanced activity of catalysts on substrates with surface protonic current in an electrical field – a review

“…They classify the TOF into those dependent on the surface area of the metal particles (TOF-s) and those dependent on the periphery of the metal particles (TOF-p), as described in Equations 1 and 2. In general catalytic reactions with heating, the TOF divided by the surface area (TOF-s) takes a constant value, while the TOF divided by the perimeter area (TOF-p) takes a constant value in reactions with the addition of an electric field 34,40,43 . The TOF (TOF-p) takes a constant value for reactions with an applied electric field 34,40,43 .…”

“…This is evidence that the reaction with an applied electric field is active only around the supporting metal. Furthermore, only when an electric field was applied, a unique peak related to the Grotthuss mechanism was detected in situ infrared measurements, suggesting the appearance of proton hopping on the catalyst surface 34,40,42,51 . These findings suggest that the reaction under the applied electric field has a completely different reaction pathway from the conventional process, as generalized in Figure 3, but on the other hand the ohmic Joule heating does indeed come from the transport of protons on the surface of the support, since this is the dominating conduction mechanism in the catalyst material.…”

“…Assuming that the proton conduction on the catalyst surface contributes to high CH 4 and CO 2 conversion for DRM with EF, the apparent electrical conductivity behavior was assessed as shown in Fig. 11 40 .…”

Low Temperature Hydrogen Production by Ethanol Steam Reforming over Supported Metal Catalysts in an Electric Field

“…To overcome that issue, we have proposed "electrocatalytic reaction in a direct current (DC) electric field" as a novel low-temperature catalytic reaction system 28) . We have succeeded in facilitating various endothermic catalytic reactions such as steam reforming 28) 35) , dry reforming 36), 37) , and dehydrogenation 38) , even at low temperatures below 473 K by applying an electric field to the catalyst bed. Therefore, we investigated the ethanol steam reforming in the electric field.…”