Jin Woo Choung

Deactivation of mordenite-type zeolite catalyst by HCl for the reduction of NOx with NH3

Abstract The stability of mordenite-type zeolite catalyst by hydrochloric acid was examined to remove NOx contained in the flue gas from an industrial waste incinerator. Cu ion-exchanged mordenite (CuHM) catalyst was is easily deactivated under selective catalytic reduction reaction conditions when water and HCl simultaneously exist in the flue gas. The deactivation of CuHM catalyst is mainly caused by the evaporation of Cu ions from the framework of mordenite structure. To enhance the acidic tolerance of the catalyst, the Si/Al ratio of the catalyst was controlled and second metals were added to the catalyst. Such a modification significantly improved the deactivation of the catalyst by HCl, commonly contained in the flue gas from the industrial waste incinerator as well as NO.

A combinatorial chemistry method for fast screening of perovskite-based NO oxidation catalyst.

A fast parallel screening method based on combinatorial chemistry (combichem) has been developed and applied in the screening tests of perovskite-based oxide (PBO) catalysts for NO oxidation to hit a promising PBO formulation for the oxidation of NO to NO2. This new method involves three consecutive steps: oxidation of NO to NO2 over a PBO catalyst, adsorption of NOx onto the PBO and K2O/Al2O3, and colorimetric assay of the NOx adsorbed thereon. The combichem experimental data have been used for determining the oxidation activity of NO over PBO catalysts as well as three critical parameters, such as the adsorption efficiency of K2O/Al2O3 for NO2 (α) and NO (β), and the time-average fraction of NO included in the NOx feed stream (ξ). The results demonstrated that the amounts of NO2 produced over PBO catalysts by the combichem method under transient conditions correlate well with those from a conventional packed-bed reactor under steady-state conditions. Among the PBO formulations examined, La0.5Ag0.5MnO3 has been identified as the best chemical formulation for oxidation of NO to NO2 by the present combichem method and also confirmed by the conventional packed-bed reactor tests. The superior efficiency of the combichem method for high-throughput catalyst screening test validated in this study is particularly suitable for saving the time and resources required in developing a new formulation of PBO catalyst whose chemical composition may have an enormous number of possible variations.

Bifunctional Ag‐based catalyst for NOx reduction with E‐diesel fuel

The excellent low‐temperature deNOx performance of Ag/AlF3/Al2O3 by simulated E‐diesel fuel has been achieved, mainly due to the multiple roles of AlF3 impregnated onto Al2O3. It increases the formation of the highly dispersed Ag ions and the catalyst surface acidity as well as the formation of the reaction intermediates such as cyanides and isocyanates. A plausible process for the formation of the surface composition of Ag/AlF3/Al2O3 has been proposed by using the results from XPS and FTIR.