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The effects of SO2 on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NOx by NH3 were examined. The addition of SO2 inhibited NOx conversion significantly below 300 oC, while no effect on NOx conversion was observed above 300 oC. TGA, TPD, and XPS results showed that the deactivation was caused by the formation of (NH4)2SO4, SO2 chemisorption on the isolated Cu2+ ion sites, as well as the formation of CuSO4-like species. Among them, the site-blocking effect of (NH4)2SO4 on Cu2+ was the primary reason for deactivation. Fortunately, 89% of deNOx activity of the poisoned catalyst was recovered after thermal treatment at 500 oC in air, where (NH4)2SO4 was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 oC, removing the adsorbed SO2 on the Cu2+ sites. The regeneration at 600 oC could not recover the activity completely, because of the high stability of CuSO4-like species.

MWW derivatives zeolite of MCM-22 with 3D layer structure, MCM-56 with partial disordered layer, MCM-36 with pillared layer and ITQ-2 with delaminated layer were prepared by hydrothermal synthesis and further modification to investigate the effect of acidic and interlayer structure on the catalytic performance of ethane dehydroaromatization and ethylene aromatization. With the retention of the MWW structure and confirmation of the intercalation or delamination efficiency, it was found that the increased exposed half-cup pocket and aluminum site on the external MWW layer structure can improve the xylene selectivity and catalytic stability. Although the amounts of total and strong acid site of H-form ITQ-2, MCM-36, MCM-56 are lower than those of MCM-22, the ratio of Lewis(L)/Bronsted(B) acid sites increases, which indicates that the exposed tri-coordinated framework aluminum in the half-cup pocket of external surface generated by exfoliation and pillaring can acted as the L acid sites. After loading Zn species, the strong acid amount and L acid sites amount are improved by the interaction between the loaded Zn species and MWW framework aluminum. The impregnated Zn species exist on the MWW zeolite with the state of ZnO and ZnAl2O4. The Zn species play roles of both ethane dehydrogenation and ethylene aromatization. The strong B acid sites play an important role for the oligomerization and aromatization of light olefins, while the excess amount of strong acid sites causes the increasing of cracking step which favors for light olefins production.

PtSe2 monolayer is previously predicted to be a two-dimensional water-splitting photocatalyst. However, the weak van der Waals (vdW) interaction between H2O and the basal surface of PtSe2 significantly undermines its photocatalytic water-splitting activities. In this work, we explore the possibility of various intrinsic defects of PtSe2 in remedying this deficiency on the basis of first-principles calculations. It is interesting to find that the introduction of Pt@Se, Se@Pt, and Se interstitial defect not only fully retain the water redox abilities of pure PtSe2 and realize spatial separation of photogenerated electrons and holes, but also can extend optical absorption range and absorption coefficients. Moreover, introduction of the three kinds of defects increase the initial weak vdW interactions between H2O and the PtSe2 surface to different extent. In particular, Pt@Se anti-site defect transform the initial weak vdW to strong chemical interaction between H2O and PtSe2 surface, and function as active reaction site. These insights demonstrate that introduction of intrinsic defects, especially the Pt@Se anti-site defect, are effective means for improving the photocatalytic water-splitting activities of PtSe2 monolayer.

Emulsion polymerization is a versatile approach to produce different polymeric nanoparticle morphologies, which can be useful in a variety of applications. However, the detailed mechanism of the morphology formation is not entirely clear. We study the kinetics of nanoparticle morphology evolution during a seeded emulsion polymerization using both experimental and computational tools. Lightly crosslinked polystyrene seeds were first synthesized using dispersion polymerization. Then the seed particles were swollen in tert-butyl acrylate and styrene monomers, and subsequently polymerized into nanoparticles of dumbbell and multilobe morphologies. It was discovered that both the seed and final particle morphology were affected by the methanol concentration during the seed synthesis. Systematically adjusting the methanol amount will not only yield spherical seed particles of different size, but also dumbbell particles even without the second monomer polymerization. In addition to methanol concentration, morphology can be controlled by crosslinking density. The kinetics studies revealed an interesting transition from multilobe to dumbbell geometries during the secondary polymerization. Based on the results, a nucleation-growth model has been proposed to describe the morphology evolution and verification was offered by computer simulation. The key discovery is that nanoparticle morphology can be kinetically controlled by diffusion of the protrusions on the seed particles. The condition of seed synthesis and crosslinking density will drastically change the seed and final nanoparticle morphology.

Two kinds of Cu-SAPO-34 catalysts, prepared with a one-pot technique using Cu- tetraethylenepentamine as co-template and an ion-exchange method, were hydrothermally treated at 750 °C for at least 16 h. The migration of Cu species during hydrothermal treatment and the corresponding effect on the selective catalytic reduction (SCR) of NOx were examined and characterized. A certain amount of CuO exists outside and inner the crystallites in the as prepared ion-exchanged sample, whereas copper is mainly atomically dispersed in the one-pot sample existing as isolated Cu2+. After hydrothermal treatment for 16 h, the amount of the inner nanosized CuO in the ion-exchanged sample reduced and the copper disperses to form more isolated Cu2+. However, surface CuO particles increase at the sacrifice of isolated Cu2+ with extending the hydrothermal treatment to 24 h. Aggregation of Cu2+ species also happens during the aging treatment over the one-pot prepared sample where the initial Cu is atomically dispersed as isolated Cu2+. The increase of the amount of the isolated Cu2+ enhances the low-temperature (