Guido Busca

The conversion of monochloropropanes and dichloropropanes over acid catalysts has been investigated in the presence of oxygen. In the temperature range of 450–550 K, dehydrochlorination of monochloropropanes to propene and HCl occurs selectively over silica–alumina, while ...

Deoxygenation of waste cooking vegetable oil and Jatropha curcas oil under nitrogen atmosphere was performed in batch and semi-batch experiments using CaO and treated hydrotalcite (MG70) as catalysts at 400°C. In batch conditions a single liquid fraction (with yields greater than 80wt.%) was produced containing a high proportion of hydrocarbons (83%). In semi-batch conditions two liquid fractions (separated by a distillation step) were obtained: a light fraction and an intermediate fraction containing amounts of hydrocarbons between 72-80% and 85-88% respectively. In order to assess the possible use of the liquid products as alternative fuels a complete chemical characterization and measurement of their properties were carried out.

ABSTRACT The application of low-temperature pyrolysis to maximize the production of liquids from organic waste (vegetable and animal fats and auto shredder residues) was studied. The samples were pyrolyzed using a batch reactor process working at 350°C for 3 hr. Catalytic pyrolysis of different organic wastes at relatively high temperature resulted to produce acceptable amounts of biofuels (gas-liquid) > 50% (wt/wt). For the gas fractions of vegetable oil and animal fats, the FT-IR analysis revealed the presence of CO2, CO, methane, acrolein, hydrocarbons, olefin, and some oxygenated compounds.

The oxidation of propane over a Mn3O4 catalyst has been investigated with oxygen to propane ratios up to 2: 1. High selectivities to the oxy-dehydrogenation product propene have been obtained at low conversions, with yields up to 5% and productivities up to ...

ABSTRACT Adsorbents and catalyst supports produced by loading different amounts of potassium acetate on alumina followed by calcination are characterized using IR spectroscopy and TPD. CO, CO2 and NOx adsorption is studied. Two different ranges of potassium loading on alumina are found, namely light and heavy doping corresponding to 1% and more than 3% K wt/wt, respectively. Light doping results in the weak adsorption of CO2 as bicarbonate species and NO2 as bidentate nitrates. Heavy doping results in the adsorption of CO2 as bidentate carbonates and NO2 as polydentate nitrate species. Three families of exposed K+ ions are observed at increasing loading.

... Interaction of magnesium ferrite with S02 three long SO bonds and one short S--O bond standing up on the surface. This spe-cies is likely formed, probably together with other ones, by outgassing sulfated MgFe204 too. ... The identification of such a species is also ...

... a Dipartimento di Ingegneria Chimica e di Processo 'GB Bonino', Laboratorio di Chimica delle Superfici e Catalisi Industriale, P.le Kennedy I-16129 Genova, Italy. b Snamprogetti, via Maritano 26, I-20097 San Donato Milanese, Milan, Italy. ...

The XRD patterns and the IR and Raman spectra of fine powders of the corundum-type sesquioxides α-Fe 2O 3 and α-Cr 2O 3, of the ilmenite-type mixed oxides NiTiO 3 and CoTiO 3, and of the mixed oxide α-FeCrO 3 is obtained from the XRD pattern, the IR and Raman spectra provide evidence for the centrosymmetric ilmenitetype superstructure in the case of α-FeCrO 3. The noncentrosymmetric alternative superstructure (LiNbO 3-like) is excluded by the validity of the mutual exclusion rule.

ABSTRACT Hypothetical monolayer loadings of niobium and tungsten oxide supported on alumina, silica, and titania were investigated as catalysts for the dehydration of glycerol to produce acrolein. Besides activity measurements, to have information about the supported structures, the catalysts were characterized by XRD, Raman spectroscopy, XPS, XANES, and FTIR combined with adsorption of pyridine and CO2. Compared with silica showing the presence of crystalline Nb2O5 and WO3, alumina and titania gave better dispersion and formation of hydrated niobate and tungstate species. Deactivation of the catalysts occurred with time on stream. However, the stability was improved considerably by adding oxygen to the feed. A dependence of the selectivity to acrolein on the Bronsted acidity of the catalyst was observed. Under anaerobic conditions, an alumina-supported mixed Nb-W-oxide catalyst gave a selectivity of more than 70% for glycerol conversions above 40%. Even better selectivity was obtained using a catalyst with tungsten oxide supported on titania, which gave 80% selectivity under aerobic conditions at high conversion.

ABSTRACT The practical application of liquids and solid bases in industrial and environmental processes is reviewed. Liquid bases include water solutions of metal hydroxides such as caustics and potash, amines, phosphorus compounds and other molecular bases, solutions and slurries of alkali and alkaline-earth carbonates, organic solutions of organometallics, and superbases. Solid bases include basic clays, alkaline-earth oxides, alkali metals containing oxides and zeolites, synthetic hydrotalcites, rare-earth oxides and mixed oxides, impregnated carbons, and supported alkali metals. Some health and safety considerations are discussed, together with process features. Conclusions about the future use of bases and the perspective of a more massive application of solid bases are offered.

The spectrum of 1,3-butadiene adsorbed on hydroxylated silica is reported. The detection of all fundamentals in the available spectral range indicates a lowering of the symmetry of the molecule upon physisorption, interpreted as being due to an s- trans to s- cis conformational change.

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ABSTRACT Introduction Several processes are under development to convert biomasses into renewable fuels (Huber et al., 2006; Demirbas, 2008). The production processes of bioethanol and biodiesel (fatty acid methyl esters) are already commercial, but they need further improvements to reduce their impact to food and agriculture market as well as to reduce their costs. Several other processes, such as pyrolysis and catalytic conversion of different renewable raw materials (wood, vegetable oils, etc.) and also of wastes are under study. A common problem of these processes is the very high oxygen content of the resulting biooils, which prevents their massive use in several countries such as in European union, because it may overcome the limits by law. Limits to oxygen content are due to the need to reduce the amount of toxic oxygenated VOCs in the waste gas and to improve the cold properties. Particularly noxious is the presence of carboxylic acids in the fuel, because of the high melting point of many acids which reduces cold properties, as well as to the corrosion behaviour associated to their acidity. Carboxylic acids frequently come from incomplete conversion of esters, such as in the case of the conversion of triglyceride-based raw materials. To improve the qualities of biooils as fuels, further catalytic treatments can be performed (Bulushev and Ross, 2011). Conversion in the presence of acidic catalysts is reported to improve fuels reducing their oxygen content. Solid acids are also reported to be active for the conversion trigliceride-based materials, such as palm oil, into hydrocarbon-rich fuels (Twaiq et al., 2003). In this work, the conversion of ethyl acetate as a model reaction for biooil refining has been investigated onacid-base catalysts. This ester is much shorter than the typical esters present in vegetable oils, however, it contains the important chemical functionality (R'-O-COR) within a short aliphatic chain (Danuthai et al., 2009). The aim of this work is to have indication on the mechanism involved in the acid- or base- catalyzed conversion of esters. Experimental Siralox 1.5/40 from Sasol was used as the catalyst for catalytic tests.This material has typically the Lewis acidic behaviour of transitional alumina(Bevilacqua et al., 2006). The catalytic experiments were carried out in a fixed-bed tubular quartz flow reactor, operating isothermally, loaded with 0.5 g of the catalyst (60-70 mesh sieved), feeding 12.5% vol/vol Ethyl Acetate (EA) in Nitrogen with total flow rates of either 40 cc/min or 80 cc/min. The carrier gas (Nitrogen) was passed through a bubbler containing high purity EA (99.5%). The temperature in the experiment was varied stepwise from 473 K to 1073 K. EA conversion was defined as usual: While selectivity to product i is defined as follows: where ni is the moles number of compound i, and νi is the ratio of stoichiometric reaction coefficients. The outlet gases were analyzed by a Gas Chromatograph Agilent 4890 equipped with a Varian capillary column Molsieve 5A/Porabond A Tandem and TCD and FID detectors in series. In order to identify the compounds of the outlet gases, a GC/MS (Thermo Scientific) was used. For FT IR studies, the adsorption/desorption process has been studied using Nicolet 380 FT-IR Spectrometer. Pressed disks of the pure catalyst powders were activated in situ in the IR cell connected with a conventional gas-manipulation apparatus, before any adsorption experimentIR spectra of the surface species as well as of the gas phase were collected upon increasing temperature in static conditions (pEA~ 4 torr). The FT IR studies of Ethyl Acetate adsorption/desorption have been carried out on several catalysts having different acid-base characters such as Siralox 1.5/40, Puralox SBa-200, Siralox 30/260, Siral 30 and Pural MG 30. Summary Ethyl Acetate conversion over Siralox 1.5/40 catalyst starts to be significant (1.2 %) at 573 K and increases further by increasing temperature up to be complete at 773 K and above at 96.5 h-1GHSV. Following the thermal evolution, the conversion increases with further formation of decomposition products. C2H4, CH3COCH3 and CH3COOHare the major reaction products, while CO, CO2, CH4, C2H6, C3H8, CH3CHO, C2H5OH, CH3COOH, (CH3CO)2O are minority products. The conversion also increases with decreasing space velocity, whereas conversion decreases with extending time on stream, due to deactivation phenomena at the catalyst surface (Figure 1). Fig. 1. (a) The conversion as a function of flowrate of 40 cc/min and 80 cc/min; (b)Conversion of Ethyl Acetate over Siralox 1.5/40 as a function of time on stream, at 723 K, total flowrate of 40 cc/min. The FT IR spectra of Ethyl Acetate adsorbed on Siralox 1.5/40 is reported in Figure2. Adsorption at room temperature gives rise to bands due to molecular EA weakly adsorbed at the surface. The band at 1705 cm-1 can be attributed to the C=O stretching mode of ester groups, while the sharp band at…

Highly crystalline H-ZSM-5 zeolite samples with crystal sizes from 0.5 to 5μm and Si/Al ratios ranging from 20 to 70 have been prepared and characterized by IR spectroscopy, SEM and XRD techniques. The surface properties of these materials have been compared with those of conventional small crystal size materials by using FT-IR spectroscopy of the surface hydroxyl groups and of adsorbed carbon monoxide. The external surface has been investigated using pivalonitrile (2,2-dimethyl-propionitrile) as an adsorption probe. Data show that the basic structure of the zeolite active sites do not depend significantly on the crystal size. Brønsted acid sites of high acid strength are constituted by bridging OH groups located inside the zeolite channels, while Lewis acid sites and weakly acidic silanol groups are found on the external surface in all cases.

Adsorption microcalorimetry and infrared measurements using CHâOH, CDâOH, and CHDâOH show the existence of at least three steps during the adsorption of methanol on alumina activated at 773 K. At very low coverages, molecules coordinated on the strongest Lewis sites are evident, which easily transform into bridged methoxide species. With increasing coverage, another form, irreversibly adsorbed at room temperature but desorbed by evacuation at 373-473 K, becomes predominant. It is identified as undissociated methanol strongly hydrogen bonded on a cation-anion couple having a strong basic character. Finally, at high coverages a reversible form hydrogen bonded to basic sites is detected. 33 references, 7 figures, 1 table.

1492 Langmuir 1993,9, 1492-1499 Surface Sites on Spinel-Type and Corundum-Type Metal Oxide Powders Guido Busca,*#t Vincenzo Lorenzelli,? Gianguido Ramis,+ and Ronald J. Willeyi ... 1978,51, 299. (33) Wood, BJ; Kirkpatrick, R. J.; Montaz, B. Am. Miner. 1986,71, 999. ...

The surface hydroxyl groups and the surface acidity of silica, silicalite, silica–aluminas, silicated aluminas, aluminated silicas and silicalite, and of H-MFI and H-FER zeolites have been investigated by IR spectroscopy. CO, pyridine and lutidine have been used as molecular basic probes. The data suggest that bridging hydroxyl groups SiOHAl are fully stable structures only in the cavities of zeolites; they