Hydrotreatment of lignin dimers over NiMoS-USY: effect of silica/alumina ratio

Sulfides of NiMo over a series of commercial ultra-stable Y zeolites were studied in an autoclave reactor to elucidate the effect of Silica/Alumina ratio (SAR=12, 30, and 80) on the...

Effect of Silica-Alumina Ratio of Catalysts on NO Decomposition Rate in Cement Kiln Exhaust

In order to deal with the pollution of NO in cement kiln exhaust, the study of NO catalytic decomposition catalyst obtained much more attention. The effect of silica-alumina ratio on NO decomposition rate in cement kiln without other reductant was studied. The NO decomposition rate of catalysts with different silica-alumina ratio was determined by infrared spectrometer. And pore structures and the microstructure of the catalyst were characterized separately by BET surface area, nitrogen adsorption-desorption and XRD. The results show that silica-alumina ratio of catalyst was preferred to be 50 with the best NO decomposition rate when the temperature was below 300 °C. The catalyst with silica-alumina ratio of 60 has the higher catalytic activity when the temperature was higher than 300 °C, and the decomposition rate achieved 70% at 600 °C. XRD results shows the crystallinity of catalysts increased as the silica-alumina ratio increased. BET surface area and the cumulative pore volume of catalysts gradually increased, and the average pore diameter gradually reduced with the increase of silica-alumina ratio.

Light olefin production using the mixture of HZSM-5/MCM-41 and γ-Al2O3 as catalysts for catalytic pyrolysis of waste tires

In this paper, micro-mesoporous HZSM-5/MCM-41 zeolites were prepared by a two-step hydrothermal method using commercial HZSM-5 with two different silica/alumina ratios (38 and 50) as starting materials. The structures, morphologies and acidity of as-prepared zeolites were analyzed using XRD, FT-IR, SEM, N2-adsorption/desorption and NH3-TPD. The HZSM-5/MCM-41 zeolites combined the acidity of microporous HZSM-5 with the pore advantages of mesoporous MCM-41. Mesopores and microspores of 3.34 and 0.95 nm in diameter were found to be present in HZSM-5/MCM-41 zeolites. When they were used to catalyze the pyrolysis of waste tires, the selectivity of light olefins for HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as starting materials was 21.42%, higher than 18.43% of HZSM-5/MCM-41synthesized using HZSM-5 with the silica/alumina ratio of 38. In order to further overcome the pore size constraints and mass transfer limitations of HZSM-5/MCM-41 zeolites for catalyzing pyrolysis of waste tires, macroporous ?-Al2O3 were mixed with HZSM-5/MCM-41 and used as catalysts. The selectivity to light olefins for the mixture of ?-Al2O3 and HZSM-5/MCM-41 prepared using HZSM-5 with the silica/alumina ratio of 50 as starting materials was 33.65%, which was obviously enhanced by the introduction of ?-Al2O3.

Enhanced Adsorption Properties of Ag-Loaded β-Zeolite towards Toluene

Two series of Ag-loaded β-zeolites with silica/alumina ratio of 25 and 36 were prepared by ion exchange technique. The silver loading was varied in a range of 2-10 wt%. The samples were characterized by low-temperature nitrogen adsorption, Infrared and UV-vis spectroscopy, and transmission electron microscopy. Adsorption/desorption properties of zeolites were examined using a specially designed setup. Toluene was used as a model hydrocarbon. It was found that adsorption capacity of zeolites grows up along with silver content increase till 8%, and reduces then. According to data of physicochemical methods, at low loading the silver exists in cluster and ionic forms, while at high loading agglomerated particles predominate, which worsens the adsorption properties.

Fast synthesis of submicron aluminosilicate (low silica/alumina ratio) zeolites under solventless microwave radiation

Sub-micron aluminosilicate zeolites with a low silica/alumina ratio are successfully synthesized by microwave solventless method.

The Preparation of Modified ZSM - 35 and its Catalysis Effect Analysis on N-Butene Isomerization

In order to study the effect that the modified ZSM - 35 as a catalyst brings to n-butene isomerization catalysis. In this paper, by considering the performance analysis brought by different silica alumina ratio, reaction temperature, concentration of nitrogen and macro porous silica gel embellish acting on butene isomerization reaction of modified ZSM - 35 molecular sieve catalyst , Al2O3 samples being "15" shows better performance; Adding appropriate amount of silicon carbide catalyst or modified silicone can further improve the selectivity of butene; Nitrogen dilution has certain help in improving butene isomerization reaction performance.

Study on Thermal Insulation Zeolite by Coal Fly Ash

This paper takes the coal fly ash as the material and makes zeolite with low thermal conductivity under a two-step synthesis for the purpose of thermal insulation. It studies main factors affecting zeolite such as the different concentration of NaOH, the solid-liquid ratio, the silica-alumina ratio, and the crystallization temperature. The optimal conditions were obtained that the NaOH concentration was 3 mol/L, the solid-liquid ratio was 10 : 1, the silica-alumina ratio was 2, and the crystallization temperature was 12°C. Zeolites have multiple pores and skeletal structures under SEM observation. The mean particle size was 2.78 um of concentrated distribution. The pore volume was 0.148 m3/g measured by BET analysis, the specific surface was 118.6 m2/g, and the thermal conductivity was 0.153 W/(m·K). Zeolite was proved to be a qualified insulation material which can be used in thermal insulation coating as a new material of energy conservation.