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Highlights: [•] The dehydration of d-xylose was examined over dealuminated and desilicated H-ZSM-5. [•] The total amount of acid sites decreased significantly for desilicated H-ZSM-5. [•] The fraction of Brønsted acid sites increased after dealumination of H-ZSM-5. [•] The fraction of Brønsted acid sites decreased after desilication of H-ZSM-5. [•] The furfural selectivity increased with increasing dealumination in H-ZSM-5. [ABSTRACT FROM AUTHOR]

Fe-ZSM-5 is an active catalyst for the selective oxidation of methane with H 2 O 2 in liquid water. To prepare the active Fe-ZSM-5 catalyst, the effect of the Fe precursor on the catalytic performance was examined. Additionally, two preparation methods, wet impregnation (WI) and ion-exchange (IE), were also applied. The prepared catalysts were characterized using various techniques, such as nitrogen physisorption, X-ray diffraction, UV–Vis spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy after NO adsorption (NO-FTIR). Fe-ZSM-5 prepared from FeCl 2 appears to be the most active among the Fe-ZSM-5 catalysts prepared from FeCl 2 , FeSO 4 , Fe(CH 3 CO 2) 2 , FeCl 3 , Fe 2 (SO 4) 3 , Fe(C 5 H 7 O 2) 3 , and Fe(NO 3) 3 using the WI method. For Fe-ZSM-5 catalysts prepared using the IE method, divalent Fe precursors, such as FeSO 4 , FeCl 2 , and Fe(CH 3 CO 2) 2 , are better than trivalent Fe precursors, such as Fe 2 (SO 4) 3 , FeCl 3 , and Fe(NO 3) 3 , in terms of catalytic activity. The active catalyst has the dominant extra-framework Fe2+ species probed with UV–Vis spectroscopy and NO-FTIR. [Display omitted] • Partial oxidation of CH 4 with H 2 O 2 in water was examined over Fe-ZSM-5. • The effect of Fe precursor during the catalyst preparation was investigated. • The active sites were probed with FT-IR spectroscopy after NO adsorption. • Correlation was made between the activity and the peak intensity in NO-FTIR spectra. [ABSTRACT FROM AUTHOR]

The direct conversion of methane into methanol is an ideal, highly promising process; however, its application remains challenging. Herein, a systematic study was carried out on the continuous gas-phase oxidation of methane into methanol with steam in the absence and presence of O 2 over Cu-mordenites (Cu-MOR) with various Cu loadings. The methanol productivity depended on the Cu/Al ratio of the Cu-MOR; it could be maximized by selecting the optimum Cu/Al ratio. Methanol productivity increased as the concentration of O 2 in the feed increased from 0 to 100 ppm. However, methanol selectivity decreased when the O 2 concentration in the feed was above 25 ppm. The stable methanol production rates based on the Cu content were 0.14 and 0.70 mol CH 3 OH/mol Cu/h at 400 °C over a Cu-MOR catalyst with 6.2 wt% Cu under anaerobic conditions and one with 3.0 wt% Cu in the presence of 25 ppm O 2 , respectively. [Display omitted] • Continuous gas-phase oxidation of methane into methanol was examined over Cu-mordenites (Cu-MOR). • The methanol productivity depends on the Cu/Al ratio of the Cu-MOR. • The methanol productivity increases with increasing O 2 concentration in the feed from 0 to 100 ppm. • The methanol selectivity decreases with increasing O 2 concentration above 25 ppm. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the SiO2/Al2O3 ratios in ZSM-5 on the gas-phase dehydration of glycerol was examined over Na-ZSM-5 and H-ZSM-5. H-ZSM-5 with a SiO2/Al2O3 ratio of 150 showed the highest glycerol dehydration activity at 315°C among the various ZSM-5 catalysts. H-ZSM-5 with a SiO2/Al2O3 ratio of 30 showed less catalytic activity than H-ZSM-5 with a SiO2/Al2O3 ratio of 150. Several characterization techniques: X-ray diffraction (XRD), the temperature-programmed desorption of ammonia or water (NH3-TPD, H2O-TPD) with mass spectroscopy, temperature-programmed oxidation (TPO) with mass spectroscopy, infrared spectroscopy (FT-IR) after pyridine adsorption, and CHNS analysis were employed. The amount of acid sites and the acid strength decreased with increasing SiO2/Al2O3 ratio in the case of H-ZSM-5. The amount of adsorbed H2O and its binding strength also decreased with increasing SiO2/Al2O3 ratio in the case of H-ZSM-5. Na-ZSM-5, having moderate Lewis acid sites, showed the least catalytic activity, which may be due to its weak acid strength for this reaction and strong adsorption of H2O on the active sites. As long as the molar ratio between water and glycerol was in the range from 2 to 11, there was no noticeable difference in the glycerol conversion but the acrolein yield increased with increasing fraction of water in the feed. [Copyright &y& Elsevier]

Abstract: In this study, a hydrocarbon (HC) trap was developed using a multi-layered zeolite, in which zeolite A and zeolite beta was selected for the water trap and the hydrocarbon trap, respectively, with the goal of reducing hydrocarbon emissions during a cold-start. The adsorption and desorption of hydrocarbons was examined in the monolithic adsorber during a vehicle test as well as in a lab-scale micro-reactor as a powder form. The competitive adsorption of water vapor and hydrocarbons in the exhaust gas from a gasoline vehicle on the hydrocarbon adsorption sites at low temperatures caused the decrease in the HC removal efficiency during a cold-start. In a multi-layered adsorption system composed of the water trap and the hydrocarbon trap, the hydrocarbon removal efficiency was greatly improved owing to the elimination of water with the hydrophilic zeolite A in the upper layer. Furthermore, the hydrocarbon desorption can be delayed because of the latent heat of desorption of adsorbed water in the upper layer. Therefore, this double-layered zeolite-based hydrocarbon trap showed the better performance compared with the conventional hydrocarbon trap during a cold-start. [Copyright &y& Elsevier]

Abstract: Sulfonic acid and aluminium modified mesoporous shell silica bead (MSHS, Mesoporous SHell Silica bead) were synthesized, respectively. Their catalytic performance was tested by dehydration reaction of d-xylose into furfural. Sulfonic acid modified MSHS showed higher selectivity of furfural than that of aluminosilicate MSHS. When aluminosilicate MSHS was used as catalyst, production of lyxose which is isomer of xylose was much more than using sulfonic acid modified MSHS. MSHS showed much more enhanced hydrothermal stability than other mesoporous silica materials, such as MCM-41. [Copyright &y& Elsevier]