PHUNG , Thanh Khoa

IR spectrometer has been successfully applied as detector for temperature-programmed techniques, i.e. NH3-TPD and H2-TPR, demonstrating an excellent flexibility, robustness and effectiveness in the proposed study. IR allowed also to detect unexpected or coproduced compounds and to avoid in many cases the expensive coupling of different...

The catalytic conversion of ethanol and diethyl ether (DEE) was studied over alumina, zeolites MFI, FER and USY, silica–alumina and calcined hydrotalcite. Zeolites, alumina and silica–alumina are active in the temperature range 453–573 K for both ethanol dehydration to DEE and to ethylene and for DEE cracking and hydrolysis, producing back...

Commercial silica-alumina catalysts prepared by different procedures have been characterized. Both present strong Lewis acidity together with Brønsted sites able to protonate pyridine. No evidence of "zeolitic" bridging OH's but significant heterogeneity of terminal silanol groups, part of which are likely "pseudobridging", was found. Similar...

IR spectra of hydroxyl groups, adsorbed CO, pivalonitrile and pyridine on three H-MFI zeolite samples and on two H-Y faujasites are reported and discussed. Samples richer in Al (H-MFI (Si/Al2 = 30) and H-Y (Si/Al2 = 5.1)) show the presence of extraframework species and the presence of Lewis acidity together with Brønsted acidity. H-MFI with...

Ethanol dehydration was investigated at atmospheric pressure with 1.43 h−1 WHSV in nitrogen, in the temperature range 423–773K over titania and zirconia, as such and modified by addition of WO3. As for comparison, data on other WO3-free and WO3-containing catalysts are also discussed: a strong Lewis acid (alumina), a covalent oxide (silica) and...

The catalytic conversion of ethyl acetate (EA) has been investigated over faujasite zeolites NaX, USY and HY. Characterization using pyridine adsorption shows that Lewis acid sites only exist on NaX while both Bronsted and Lewis acid sites are evident on both HY and USY. Catalytic experiments were performed in gas phase from 473 K to 973 K at...

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Ethanol dehydration was investigated over commercial H-FER, H-MFI, H-MOR, H-BEA, H-Y and H-USY zeolite samples, and alumina and silica alumina for comparison. The catalysts were characterized using FT-IR spectroscopy of the surface OH groups and of adsorbed CO and pyridine. UV–vis, Raman and TG-DTA were applied to characterize coke, formed more...

Nickel catalysts supported on pure alumina (Puralox) and 5% silica-containing alumina (Siralox) have been prepared, characterized (XRD, UV-vis-NIR, IR, H2-TPR and FE-SEM) and tested. It is confirmed that small amounts of silica hinder the surface area loss of alumina upon calcination, allowing the retention of higher surface areas also when NiO...

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Thermal and catalytic conversions of palm oil were investigated at 693 K. The conversions of acetic acid and ethyl acetate in the gas phase were also investigated over the same catalysts as model reactions. The acido-basicity of the catalysts was assessed by IR spectroscopy of adsorbed pyridine. Oxide catalysts slightly decrease the liquid...

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Conversion of ethanol to hydrocarbons was investigated over H-ZSM-5 zeolite and its modification by addition of phosphorus, iron and nickel. Reaction is realized in a tubular flow reactor at atmospheric pressure. Catalyst characterization was performed by UV-vis, TG-DTA, XRD, NH3-TPD, and IR spectroscopy of the surface OH groups and of adsorbed...

Conversion of ethanol was investigated over four commercial aluminas prepared by different industrial procedures and one commercial silica-alumina. Characterization was performed by TEM, XRD, SBET and porosity measurements, and IR spectroscopy of the surface OH groups and of adsorbed CO and pyridine. Different features are attributed to...

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