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As an efficient scheme, catalytic combustion can be used to eliminate chlorinated volatile organic compounds (CVOCs). To avoid the formation of more toxic by-products, it is essential to reveal the relationship between the chlorine-containing products and redox properties of catalyst. In the present study, the activity for chlorobenzene (CB) oxidation, HCl production, and formation of by-products polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs)were investigated over γ-Al2O3-supported transition metal (Cr, V and Cu) oxide catalysts. The results showed that the 10Cr-Al catalyst with relatively high specific surface areaand more oxygen absorbed than other catalysts exhibited higher catalytic oxidation activity for CB. The temperatures needed for 90% conversion of CB (T90) were 331, 353 and 386 °C for 10Cr-Al, 10V-Al and 10Cu-Al, respectively. The amount and type of acid sites on the surface of catalysts play an important role in the distribution of products and by-products. It was found that the increase of acid sites and the presence of Brønsted acid (B-acid) significantly improve the HCl selectivity of catalysts. More HCl was formed on the 10V-Al catalyst with B-acid sites. Meanwhile PCDD/Fs and PCBs detected in the by-products had a tight relationship with the acidity sites and redox performance of the catalyst. The yields of ∑PCDD/Fs and ∑PCBs were the largest on 10V-Al at T10, reaching 25.60, 66.93 mmol/mol CB, respectively. The obtained results provided theoretical support for the subsequent development of CVOCs catalytic oxidation catalysts and the control of toxic by-products.

Ordered mesoporous copper incorporated Al2O3(Cu/Al2O3) with high Cu dispersion were prepared by a facile solution combustion synthesis method using aluminum nitrate and copper nitrate as oxidants and urea as fuel. It is a facile and green route to synthesize catalysts for dimethyl ether directly from syngas. Cu/Al2O3catalysts were characterized by XRD, N2adsorption–desorption, SEM-EDS, and H2-TPR. The results indicate that the catalysts obtain an ordered mesoporous structure and copper is homogenously dispersed. The mesoporous Cu/Al2O3catalysts were utilized as bifunctional catalysts in syngas to dimethyl ether reaction (STD). The copper content affects the catalytic performance in STD reaction. The CO conversion and DME selectivity of Cu/Al2O3with 15% copper molar ratio achieve 52.9% and 66.1%, respectively. Moreover, the mesoporous Cu/Al2O3catalysts show excellent stability in STD reaction.

Abstract

A mesoporous sulfated zirconia–silica material with high hydrothermal stability was prepared by a two-step hydrothermal treatment process in a pH range of 1.65–3. This material still showed high surface area, large pore volume, and uniform structure after steam treatment at 800 °C for 5 h. In cumene cracking, the material exhibited relatively steady catalytic activity even after steam treatment at 600 °C for 2 h.