Use of crystallite-scale features to predict the reactor-scale performance of a three-way catalyst

Crystallite-Scale Approach To Predict the Oxygen Storage Capacity of a Three-Way Catalyst for Natural Gas Applications

“…The value of the surface diffusivity of oxygen at 400 °C is estimated to be 2 × 10 –15 m 2 /s. This is the same as the value estimated with CO as the reductant at 600 °C . Since the surface diffusivity is expected to increase with the temperature, it can be deduced that for a fixed temperature, the surface diffusivity is higher with H 2 as compared to CO as the reductant.…”

“…The kinetic constants for reaction are also given in Table but are not used for the simulations with H 2 as the reductant. The values of kinetic parameters k 1f , k 3f , k 4f , k 6f , k 7f , and k 9f are taken from Rajbala et al, whereas that of k 5f is taken from Gong et al after correcting for the units. The initial guess for k 2f is taken from Gong et al and later adjusted to predict the experimental data.…”

“…The model developed at the crystallite scale is described in more detail in a previous publication and is summarized here . The number of Pd crystallites present on the ceria surface ( N c ) is estimated using eq .…”

Removing NOx, CO and HC from automobile exhaust based on chemical looping combustion

“…However, considering that NO conversion was determined based on the outlet NO concentration at the very initial reaction stage, the amount of the oxidative OC generated through reaction (1) was very small and negligible, so the CLC reduction reaction (2) was negligible too. Thus, it could be considered that NO conversion on the curve was due to the contributions of both the CLC reaction and the catalytic reaction (5), and NO conversion on the □ curve by subtracting NO conversion on the curve from that on the curve corresponded to the additional contribution of the catalytic reaction . …”

“…Automobile exhaust is the main source of air pollution, especially in big cities. Three-way catalysts (TWCs), [1][2][3][4] which generally comprise platinum (Pt), palladium (Pd) and rhodium (Rh) as the active components, are commonly used to remove nitrogen oxides (NO x ), carbon monoxide (CO) and hydrocarbons (HC) from automobile exhaust. [5][6][7][8][9] Because of the high costs of conventional TWCs, the development of a TWC without using platinum group metals (PGMs) has been an important issue in this field.…”