Cerium doped copper/ZSM-5 catalysts used for the selective catalytic reduction of nitrogen oxide with ammonia

The CuCe/ZSM-5 catalysts with different cerium loadings (0, 0.5, 1.0, 1.5 and 2.0wt.%) was investigated to evaluate the correlation between structural characteristics and catalytic performance for the selective catalytic reduction (SCR) of NO by NH3. It was found that the addition of cerium increased copper dispersion and prevented its crystallization. According to the results of X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction by hydrogen (H2-TPR), copper species were enriched on the ZSM-5 grain surfaces and part of copper ions was incorporated into the cerium lattice. Addition of cerium improved the redox properties of the CuCe/ZSM-5 catalysts, owing to the higher valence of copper and mobility of lattice oxygen than those of Cu/ZSM-5 catalyst. Hence the introduction of cerium in Cu/ZSM-5 improved significantly NO conversion. On the one hand, the cerium introduction into Cu-Z enhances their low-temperature activities. 95% NO conversion is reached around 197°C for Cu-Z while the corresponding temperature value decreases to 148°C for CuCe4-Z. On the other hand, the temperature range of efficient NO reduction (95%) also extends to higher temperature when the cerium are added to Cu/ZSM-5. Among the Cu-Ce/ZSM-5 catalysts tested, the CuCe4-Z sample exhibits the highest catalytic activity with the temperature range for 90% NO removal of 148-427°C

Characterization of self-adjoint domains for regular even order C-symmetric differential operators

Let $C$ be a skew-diagonal constant matrix satisfying $C^{-1}=-C=C^{\ast}$. We characterize the self-adjoint domains for regular even order $C$-symmetric differential operators with two-point boundary conditions. Thepreviously known characterizations are a special case of this one

Characterization of self-adjoint domains for regular even order C-symmetric differential operators

Let C be a skew-diagonal constant matrix satisfying C −1 = −C = C . We characterize the self-adjoint domains for regular even order C-symmetric differential operators with two-point boundary conditions. The previously known characterizations are a special case of this one

A facilitated synthesis of hierarchically porous Cu-Ce-Zr catalyst using bacterial cellulose for VOCs oxidation

Highly active CuO-CeO2-ZrO2 catalysts were prepared by sol-gel method, using environmentally friendly bacterial cellulose (BC) as structure directing regent. The catalyst designed with commercial BC (Com-BC) exhibited catalytic performances in toluene (T100 =220 oC) and ethyl acetate oxidation (T100 =170 oC) superior to the catalysts prepared by traditional methods. Furthermore, excellent stability was obtained and no deactivation was observed during the 100 h on stream in toluene and ethyl acetate oxidation at T100. The excellent activity and stability of Com-BC can be explained by the hierarchically porous structure, abundant oxygen vacancies, and good reducibility

Characterization of Self-Adjoint Domains for Two-Interval Even Order Singular C-Symmetric Differential Operators in Direct Sum Spaces

This paper is concerned with the characterization of all self-adjoint domains associated with two-interval even order singular C-symmetric differential operators in terms of boundary conditions. The previously known characterizations of Lagrange symmetric differential operators are a special case of this one

Characterization of self-adjoint domains for regular even order CC-symmetric differential operators

Let $C$ be a skew-diagonal constant matrix satisfying $C^{-1}=-C=C^{\ast}$. We characterize the self-adjoint domains for regular even order $C$-symmetric differential operators with two-point boundary conditions. Thepreviously known characterizations are a special case of this one

No Evidence of Bacterial Symbionts Influencing Host Specificity in <em>Aphis gossypii</em> Glover (Hemiptera: Aphididae)

The cotton-melon aphid, Aphis gossypii Glover, is a polyphagous insect pest with many host-specialized biotypes, such as the Cucurbitaceae- and Malvaceae-specialized (CU and MA) biotypes. Bacterial symbionts were reported to determine the host range in some aphids. Whether this is the case in A. gossypii remains unknown. Here, we tested the host specificity of the CU and MA biotypes, compared the host specificity between the wingless and winged morph within the same biotype, and analyzed the composition of the bacterial symbionts. The reproduction of the CU and MA biotypes reduced by 66.67% and 82.79%, respectively, on non-native hosts, compared with on native hosts. The composition of bacterial symbionts was not significantly different between the CU and MA biotypes, with a Buchnera abundance >95% in both biotypes. Meanwhile, the winged morph produced significantly more nymphs than the wingless morph on non-native hosts, and the Buchnera abundance in the winged morph was only about 10% of that in the wingless morph. There seemed to be a relationship between the Buchnera abundance and host specificity. We regulated the Buchnera abundance by temperature and antibiotics, but did not find that a low Buchnera abundance resulted in the high reproduction on non-native hosts. We conclude that the host specificity of A. gossypii is not controlled by specific bacterial symbionts or by Buchnera abundance