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The alkali metal-induced deactivation of a novel CeO(2)-WO(3) (CeW) catalyst used for selective catalytic reduction (SCR) was investigated. The CeW catalyst could resist greater amounts of alkali metals than V(2)O(5)-WO(3)/TiO(2). At the same molar concentration, the K-poisoned catalyst exhibited a greater loss in activity compared with the Na-poisoned catalyst below 200 °C. A combination of experimental and theoretical methods, including NH(3)-TPD, DRIFTS, H(2)-TPR, and density functional theory (DFT) calculations, were used to elucidate the mechanism of the alkali metal deactivation of the CeW catalyst in SCR reaction. Experiments results indicated that decreases in the reduction activity and the quantity of Brønsted acid sites rather than the acid strength were responsible for the catalyst deactivation. The DFT calculations revealed that Na and K could easily adsorb on the CeW (110) surface and that the surface oxygen could migrate to cover the active tungsten, and then inhibit the SCR of NO(x) with ammonia. Hot water washing is a convenient and effective method to regenerate alkali metal-poisoned CeW catalysts, and the catalytic activity could be recovered 90% of the fresh catalyst.

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In this study, graphite powder (GP) was introduced into the conductive cellulose/polypyrrole (PPy) composite films to increase their conductivity and thermal stability. The GP was dispersed in ionic liquid 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) before the dissolution of cellulose, and the cellulose/GP/PPy films were prepared by in situ chemical polymerization of PPy nanoparticles on the film surface. The structural characteristics and properties of the composite films were investigated in detail. The GP flakes, which were embedded in the cellulose matrix, increased the thickness and decreased the density of the films, leading to the decrement of mechanical properties. However, the thermal stability of the films was significantly improved by the incorporation of graphite, and the composite film could even substantially maintain the original shape after being burned. In addition, the electrical conductivity of the films was increased seven times, leading to the excellent electromagnetic interference shielding effectiveness. The cellulose/GP/PPy film could be considered as a potential candidate for the effective lightweight electromagnetic interference shielding materials in electronics, radar evasion, aerospace, and other applications.

To improve N 2 selectivity and lower the cost, WO 3 in V 2 O 5 /WO 3 -TiO 2 was substituted by a low cost composition Fe 2 O 3 for selective catalytic reduction (SCR) of NO with NH 3 . The SCR reaction over V 2 O 5 /Fe 2 O 3 -TiO 2 mainly followed the Eley-Rideal mechanism (i.e. the reaction between activated ammonia species and gaseous NO). There were two active components on V 2 O 5 / WO 3 -TiO 2 for the activation of adsorbed NH 3 (i.e. V 5+ and Fe 3+ ). The acid sites on V 2 O 5 /Fe 2 O 3 -TiO 2 mainly resulted from the support Fe 2 O 3 -TiO 2 , so the adsorbed NH 3 preferred to be activated by Fe 3+ rather than by V 5+ . V 5+ on V 2 O 5 /Fe 2 O 3 -TiO 2 could accelerate the regeneration of Fe 3+ on Fe 2 O 3 -TiO 2 due to the rapid electron transfer between V 5+ and Fe 2+ on the surface, so the activation of adsorbed NH 3 by Fe 3+ was promoted. As some NH 3 adsorbed on V 2 O 5 /Fe 2 O 3 -TiO 2 was not activated by Fe 3+ , the inactivated NH 3 could then be activated by V 5+ on the surface. As a result, 2% V 2 O 5 /Fe 2 O 3 -TiO 2 showed excellent SCR activity, N 2 selectivity and H 2 O/SO 2 durability at 300-450 1C. Furthermore, the emission of 2% V 2 O 5 /Fe 2 O 3 -TiO 2 to the fly ash can be prevented by an external magnetic field due to its inherent magnetization. Therefore, 2% V 2 O 5 /Fe 2 O 3 -TiO 2 could be a promising low-cost catalyst in NO emission control.

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