Key factor for the anti-Arrhenius low-temperature heterogeneous catalysis induced by H⁺ migration: H⁺ coverage over support

Abstract

Low-temperature heterogeneous catalytic reaction in an electric field is anticipated as a novel approach for on-demand and small-scale catalytic processes.

Support effects on catalysis of low temperature methane steam reforming

“…19,21 The calculated apparent activation energy was 1.27 eV (300 C < T < 500 C) for CeO 2 , 0.89 eV for Nb 2 O 5 and 0.71 eV for Ta 2 O 5 , respectively. However, all samples showed anti-Arrhenius behaviour 27 at lower temperature regions under wet conditions. Such conductive increases at low temperatures under a wet atmosphere are attributable to the increase in the water adsorption amount or relative humidity with decreasing temperature, resulting in enhancement of surface proton conduction via the Grotthuss mechanism.…”

Recent progress in use and observation of surface hydrogen migration over metal oxides

“…13(a), black closed plot). 16 Furthermore, partial pressures of H 2 positively influenced the reaction rate at this temperature region, where anti-Arrhenius-like behaviour was observed. As described in Section 2.4, Ru-based catalysts conventionally show negative values on the H 2 reaction order because of H 2 poisoning.…”

“…Hydrogen migration plays an important role in various catalyses such as hydrogenation-dehydrogenation of hydrocarbon, 1-5 CO 2 reduction [6][7][8][9] and NH 3 synthesis. [10][11][12][13][14][15][16][17] However, the utilisation of hydrogen migration is not limited to catalysis. It is also fundamentally important for catalyst preparation, 18,19 hydrogen storage, 20,21 fuel cells and sensors.…”

“…[39][40][41] This active migration is called surface protonics. It has been revealed that surface protonics plays a key role in activating the cleavage of strong bonds, as in the NRN bond in N 2 , [13][14][15][16][17]42,43 and the C-H bond in hydrocarbons, as in CH 4 [42][43][44][45][46] and methylcyclohexane (MCH). 4,5 Those activations make it possible to catalyze hydrogen production and formation of the hydrogen carrier, even at low temperatures (o500 K).…”

“…To date, this method has been applied to various catalytic reactions, revealing that surface ion conduction participates in low-temperature catalysis. 39,40,84 Herein, we have described reaction mechanisms that are relevant to surface protonics under a H 2 atmosphere: NH 3 synthesis proceeds via N 2 H [11][12][13][14][15][16][17] and dehydrogenation of methylcyclohexane (MCH) facilitated by H + collision. Both compounds are promising hydrogen carrier candidates.…”