Alkaline treatment desilication has been employed to prepare mesopore containing zeolite ZSM-5 catalyst. With the increasing treatment temperature and prolonging treatment duration, the rise in the introduced mesopore volume has been observed. Desilication has been found to occur along with the desilication process, which is suggested by the slight decrease in the Si/A1 ratio of zeolite ZSM-5 after remarkable desilication as well as the decreased acid quantity demonstrated by NHa-TPD. The prepared mesopore containing ZSM-5 catalyst shows noticeable enhancement in catalytic stability in methanol to propylene reaction.

A series of boron isomorphously framework-substituted ZSM-5 (Bx–Al–ZSM-5, Si/Al=200, B/Al=X) were synthesized and used to selectively transform methanol to propylene (MTP). The catalytic stability can be significantly influenced by B incorporation. In comparison with the conventional ZSM-5, the B1–Al–ZSM-5 catalyst afforded a 7-time-long catalytic life under a space velocity of WHSV 1.8h−1 (700h for B1–Al–ZSM-5 and 100h for ZSM-5, respectively). The enhancement of catalytic stability can be attributed to the increase of weak acid sites on the ZSM-5 catalysts.

A novel route for anti-deactivation of methanol-to-propylene catalyst has been established through supporting nano-gold on ZSM-5, which efficiently reinforces the catalytic stability due to the effect of gold nanoparticles on the stabilization of dehydrogenation intermediates within the coking process.

Mesoporous core-shell composites with large-pore silica shells are highly desired for a broad spectrum of applications. We report an ultra-dilute liquid-phase coating strategy in an acidic medium for controllable synthesis of uniform micro/mesoporous core-shell composites zeolite@SBA-15 comprising zeolite cores and mesoporous silica SBA-15 shells using triblock compolymer Plunoric P123 as a template. Structural characterizations show that the core-shell composites possess tunable specific surface areas (115-228 m(2) g(-1)), large pores (similar to 7.0 nm in diameter) with plenty of mesotunnels (similar to 3.0 nm) from silica shells, original crystalline zeolite frameworks, and opened junctions between micropores and mesopores. The silica shells have ordered 2-D hexagonal mesopore channels, most of which are annularly parallel (fingerprint-like arrangement) to the anisotropic zeolite faces. The shell-thickness is crystal face-dependent, which could be facilely tuned in the range of 30-45 and 40-120 nm on a pinacoids/dome faces and b pinacoids of a zeolite single-crystal, respectively. Moreover, the synthesis parameters such as MgSO4 additive, stirring rate, acidity, temperature and reaction time show great influences on the formation of uniform core-shell composites. Post-hydrothermal treatment at 100 degrees C has been for the first time adopted to improve mesostructural regularity of the core-shell composites. A scheme regarding surface-induced micellization and hydrothermal rearrangement of mesostructured silica shells in the coating process is proposed to illustrate the formation of core-shell composites. The core-shell composite HZSM-5@SBA-15 (HZ@S15) was employed as a catalyst for methanol to propylene (MTP) conversion, and shows excellent catalytic performance with high methanol conversion (similar to 98%) and propylene to ethylene (P/E) ratio (similar to 10.7) as well as propylene selectivity (similar to 39%).

A novel route is proposed for the preparation of mesopore containing zeolite ZSM-5 via in situ hydrothermal treatment of a solution containing alkali-dissolved SBA-15 containing carbonized surfactant P123 in the mesopores; it exhibited prominent stability enhancement for methanol to propylene reaction.

Series of Rh/SBA-15 catalysts were prepared by impregnation and grafting method applying different Rh precursors. The catalytic behaviors of N2O decomposition over these catalysts were tested in an automated eight flow reactor system. The catalysts were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that the dispersion of Rh species on the catalysts is closely related to the molecular size and the hydrophobic property of the precursors comparing to the hydrophilic support, better dispersion results were found in catalysts by impregnation of smaller precursors, while by grafting better dispersion resulted from big precursor. On the other hand, the activities of the catalysts match well with the Rh dispersion status. Rh/SBA-15-CDCR starting from [(CO)2RhCl]2 showed good dispersion and gave the best N2O decomposition activity.

The coupling process of dehydrogenation of 1,4-butanediol and hydrogenation of dimethyl maleate over CuO/SiO2 catalysts to produce one important fine chemical γ-butyrolactone was carried out in a continuous fixed bed reactor under atmospheric pressure. Compared to the conventional reaction process, the activities of catalysts for hydrogenation of dimethyl maleate and dehydrogenation of 1,4-butanediol were enhanced through the coupling process. Under optimum reaction conditions, the conversion of 1,4-butanediol and dimethyl maleate reached 100%, and the selectivity of γ-butyrolactone was 98%. The results of XRD and TPR indicated that the optimized loading weight of CuO was about w=21%, which is in accordance with the monolayer dispersion threshold value. The active sites were Cu0, the proportion of congregated CuO were increased dramatically as CuO loading weight was higher than 21%.

Cu/SiO2 catalysts were modified by the sodium by impregnation method, catalytic activity for hydrogenation of benzaldehyde to non-chloride benzyl alcohol was investigated in a continuous flow fixed-bed reactor under atmospheric pressure. It was found that the selectivity of benzyl alcohol was significantly enhanced over sodium modified Cu/SiO2 catalysts. The optimum loading amount of sodium on Cu-based catalysts is about w=1.0%. The Na-CuO/SiO2 catalysts were characterized by XRD, H2-TPR, BET and FT-IR, the results revealed that reducing temperature of CuO was increased after modification by sodium. Meanwhile, the sodium species reduced the intensity and amounts of the acidic centers on catalytic surface, which effectively inhibited the formation of toluene at higher temperature.

A series of Ag/ZrO2 catalysts were prepared by impregnation method. The catalytic performance for selective oxidation of 1,2-propylene glycol to methyl glyoxal was investigated. Under optimum reaction conditions [V(N-2) : V(O-2)=300 : 19, n(O-2)/n(alcohol)= 1.2, LHSV=3.2 g/(g(.)h) and temperature=673 K], the conversion of 1,2-propylene glycol got to 95.7%, and the selectivity to methyl glyoxal was 55.3%, being higher than that over conventional electrolytic silver catalyst. The UV-vis DRS and XPS results indicated that the existence of large amount of Ag+ and Ag-n(delta+) in Ag/ZrO2 catalysts contributes to the enhancement of catalytic activity.

Consecutive hydrogenation of methyl benzoate to non-chloride benzyl alcohol over K-MnO/gamma-Al2O3 and Cu/SiO2 catalysts was investigated in a fixed-bed stainless-steel reactor. The effects of reaction conditions on catalytic activity were also studied. The results indicated that Cu/SiO2 prepared by adsorbed-precipitation method owned larger pore diameter and volume than others, CuO dispersed well on the surface of catalyst, and it was easily reduced at relative lower temperature. K-MnO/gamma-Al2O3 and Cu/SiO2-C15.2 exhibited higher activity and selectivity for continuous hydrogenation of methyl benzoate to benzyl alcohol, the conversion of methyl benzoate was 89.2% and the selectivity of benzyl alcohol reached 84.1%. Molar ratio of hydrogen to benzaldehyde was increased in consecutive hydrogenation process, which is beneficial to enhancing the selectivity of benzyl alcohol. Characterization results of XRD, SEM and TPR revealed that CuO dispersed well on Ci/SiO2-C catalyst which prepared by adsorption-precipitation method, and it showed best activity for hydrogenation of benzaldehyde to benzyl alcohol.

A new synthetic method for the preparation of N-alkylhexahydroazepine by one-step catalytic alkylation and hydrogenation of caprolactam has been developed. Alkylated caprolactam was firstly synthesized by catalytic alkylation of caprolactam with alcohol and then directly hydrogenated into N-alkylhexahydroazepine over Cu-ZnO/γ-Al2O3 catalyst.

The selective oxidation of a series of alcohols to their corresponding carbonyl products was carried out over a rationally designed in situ electrolytic nano-silver/zeolite film/copper grid (SZF) catalyst, which was prepared by a combination of the seed-film method for the fabrication of an ultrathin zeolite film and the in situ electrolytic process for the formation of highly dispersed silver nanoparticles. At a relatively low reaction temperature (ca. 320 degrees C), the SZF catalyst with highly dispersed in situ electrolytic silver nanoparticles exhibited much higher activity for the oxidation of mono-alcohols and higher selectivity for ketonic aldehyde in the oxidation of di-alcohols than the conventional bulk electrolytic silver catalyst. On the basis of the combination of diffuse reflectance ultraviolet visible spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and thermoanalysis, the remarkably high activity and selectivity of the SZF catalyst was attributed to the highly dispersed silver nanoparticles, which were stabilized by the zeolite film against sintering, and, accordingly, a large amount of Ag+ ions and Ag-n(delta+) clusters existed in the silver nanoparticles. The improvements of the catalytic performance of the SZF catalyst in a wide application extension will bring new concerns in both theoretical and applied fields. (c) 2005 Elsevier Inc. All rights reserved.

Al- and Zn-containing mesoporous molecular sieves (SBA-15) were prepared by an impregnation method and were used as catalysts for the catalytic dehydrogenation and cracking of industrial dipentene, an important natural feedstock. The catalysts were characterized by X-Ray fluorescence spectroscopy (XRF), X-Ray diffraction (XRD), N2 adsorption/desorption, transmission electron microscopy (TEM), magic angle spinning nuclear magnetic resonance (27Al MAS NMR) and Fourier transform infrared spectroscopy (FT-IR) techniques. The characterization results suggest that the active components were introduced without changing the mesostructure of SBA-15. FT-IR revealed that Al/SBA-15 shows weak Brönsted acidity and strong Lewis acidity, while Zn/SBA-15 only possesses moderate Lewis acidity. Dehydrogenation and cracking products, such as toluene, were found in the dipentene conversion over Al/SBA-15, while for Zn/SBA-15, p-cymene was the major dehydrogenation product. Along with the strong Brönsted acidity and high cracking activity of HZSM-5, our results suggest that the reaction pathway is determined by the acidic sites. Stability tests showed the deactivation is also related to the acidity. The highest yield of p-cymene reaches to 86.7% on Zn/SBA-15 at 723K.

A novel catalyst of silver nanoparticles over a zeolite film-coated copper grid (SZFC) has been fabricated via an in situ electrolytic method; it exhibited high catalytic activity and selectivity at a relatively low temperature for the partial oxidation of 1,2-propylene glycol to methyl glyoxal.