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Abstract: The search for new energy sources has impulsed hydrocarbon production from methanol and ethanol over ZSM-5 zeolites. Iron incorporation by different methods has led to a variety of chemical applications. Thus, hydrocarbon production from ethanol was evaluated using a [Fe,Al]ZSM-5 zeolite which was synthesized without nitrogenated templates, using ethanol and crystallization seeds and partially substituting iron for aluminium in the reaction mixture. Characterization was done by X-ray diffraction (XRD), Fourier-transform infra-red spectroscopy (FTIR), temperature programmed reduction (TPR), temperature programmed desorption of ammonia (TPD), nitrogen adsorption, electron paramagnetic resonance (EPR) and photoacoustic spectroscopies. Iron content in the synthesized samples varied from 0.02 to 1.82%. The obtained samples were used for the ethanol transformation, producing hydrocarbons from ethene to aromatics. Maximum production of liquid hydrocarbons was achieved with the zeolite with 0.5% iron. The procedure for obtaining the acid form of the zeolites, involving ammonium exchange and calcinations, has changed the iron species, probably with extraction from the structure, migration and agglomeration. [Copyright &y& Elsevier]

Abstract: The solid by-product of oil shale processing (PETROBRAS–Brazil) was used as a raw material to synthesize Na–A and –X zeolites. Two preparation methods using the same starting material composition were carried out. In Method (1), alkaline fusion was used to prepare a glass, which was then hydrated by refluxing. The largest amount of crystallinity was reached with 2h 30min of refluxing. In Method (2), alkaline fusion was followed by hydrothermal treatment. The most crystalline sample was obtained after 12h of heat treatment, and after 96h hydroxysodalite zeolite was formed. In both procedures, the synthesis products were mainly composed of Na–X zeolite, whose content was influenced by the crystallization time, and of Na–A zeolite, with a practically constant content. [Copyright &y& Elsevier]

Abstract: ZSM-5 zeolites modified by iron incorporation through post-synthesis ion exchange and those synthesized with iron addition to the synthesis medium were compared in the reaction of liquid hydrocarbons production from ethanol. AA, TPR, FTIR, XRD, SEM, nitrogen adsorption and photoacoustic spectroscopy were used for the samples characterization. Acid leaching and ammonium exchange were tested for obtaining the acid form of the zeolite, with similar results, the major difference being a faster deactivation in the latter case. The best yield of liquid hydrocarbons was obtained with the samples with low iron content. The product distribution in both gaseous and liquid phases was independent of the way the zeolite was obtained or the iron was introduced, with major variations only with time (due to deactivation). [Copyright &y& Elsevier]

ZnO was supported in three different zeolites aiming at new photocatalysts. In the zeolite NaA, the crystallization of ZnO was on the external surface while for zeolites NaY and USY it occurred predominantly inside the micropores, as indicated by XRD diffractograms and by transmission electron microscopy. The bandgap and the zero point of charge indicated that the increase in ZnO content approaches these parameters to values of pure oxide. In the catalysts supported on USY, significant changes were not observed in the bandgap values due to the incorporation of ZnO in their micropores. Therefore, each synthesized catalyst has potential applications in heterogeneous photocatalysis. [ABSTRACT FROM AUTHOR]

The influence of using hydrogen or nitrogen as carrier/reagent gas in catalytic cracking of soybean oil was studied. The used catalyst was commercial zeolite ZSM-5 with Si/Al molar ratio of 20. The system consisted of a micro fixed-bed reactor into which crude or refined soybean oil was pumped at 0.07 g/min with gas flow rate of 42 mL/min at 723 K for 45 min. Product distribution was very different depending on using hydrogen or nitrogen as carrier/reagent gas and on the soybean oil. Over ZSM-5, the refined and unrefined oils produced more liquid fuel under H 2 flow than under N 2 flow. The highest amount of gasoline was produced with refined oil under H 2 flow. [ABSTRACT FROM AUTHOR]

The global economic and population growth has significantly increased the demand for fuels. On the other hand, the strictness of environmental legislation and the depreciation of fossil fuel reserves have motivated the research for alternative energy sources. With this purpose, the preparation and characterization of catalysts based on Beta nanozeolites were described in this work, aiming to find active and selective catalysts to produce biofuels through the cracking of crude soybean oil. The samples were prepared by using different organosilanes such as phenylaminopropyltrimethoxysilane (PHAPTMS), phenyltrimethoxysilane (PHMTS) and aminopropyltriethoxysilane (APTES) to functionalize the Beta zeolite seeds. The silanized seeds produced solids with smaller crystallites, more framework aluminum and different textural and acidic properties as compared to the Beta nanozeolite prepared without organosilane. APTES produced the solid with the smallest crystallites while PHAPTMS produced the sample with the highest external area, the differences being related to agglomeration of nanoparticles, generating voids related to the size of organosilane chains. The catalysts showed different selectivities during the cracking of crude soybean oil, depending on the organosilane used in the preparation. This finding was related to the different acidic properties and to the different particles size and porosity of the solids. The Beta nanozeolite obtained without any organosilane produced more gaseous compounds (C2–C4), due to the largest percentage of strong acidic sites, whereas those obtained with organosilanes were more selective to liquid hydrocarbons. The sample prepared with APTES was the most active and selective to hydrocarbons in the range of gasoline, diesel and kerosene, because of its smallest crystallite size and low acidity, as well as to the agglomeration of nanoparticles, which facilitates the hydrogen transfer reactions. Moreover, the sample prepared with PHMTS was the most selective to hydrocarbons in the gasoline range (C5–C11) while that obtained with PHAPTMS was the most selective to oxygenates. These changes were related to the combined effects of crystallite sizes, porosity and acidity on the catalytic properties of the solids, in the different pathways of the complex reaction network of cracking of soybean oil. It was shown that different organosilanes allowed tailoring the catalytic properties of Beta nanozeolites to produce biofuels or chemicals for several applications. [ABSTRACT FROM AUTHOR]

Ethanol steam reforming for hydrogen production was evaluated using Cu–Ni/Nb x O y catalyst prepared by ion exchange (IE), wet impregnation (WI) and co-precipitation (CP). The catalysts were characterized by textural analysis, chemisorption of H 2 and N 2 O for metallic area determination, XDR (calcined and in situ reduced samples), TPR-H 2 , TPD-NH 3 , MET/EDX e TPO-O 2 . Differences in crystal structure and metal-support interaction have altered the reducibility of the catalysts, besides metal surface area and crystallite size of Cu and Ni. The catalytic tests, using ethanol:water molar ratio of 1:10, temperature of 450 and 500 °C, demonstrated high H 2 yield and stability, except for the IE catalyst at 500 °C, which favored the ethylene formation by ethanol dehydration. The main route for H 2 obtainment in all cases was ethanol decomposition. The temperature increasing up to 500 °C favored the by-product CH 4 reforming. The weakest metal-support interaction on WI catalyst provided the fully reduced metal phase, however, support characteristics achieved by this preparation method led to the filamentous coke formation. TEM images showed that different crystalline structures of the support modified the mechanism of the reaction and consequently the type of coke deposited on the surface. The CP catalyst showed low coke deposition and no metal sintering, stoichiometric H 2 /CO 2 ratio, less than 5% of CH 4 , and no CO, which makes it the best candidate for hydrogen production by ethanol steam reforming. [ABSTRACT FROM AUTHOR]

It is possible to produce hydrocarbons by hydrocracking of biomass, such as those produced by crude oil cracking. This product can be incorporated as raw material in petrochemical industry and used as petroleum fractions without any changes on engines. The hydrocracking process was performed over NaZSM5 and HZSM5, where the improvement of this acidity was carried out by ion exchange with ammonia followed by calcination. The reactions were performed on a stainless steel fixed bed reactor. The catalyst was evaluated at 723 K and 138 kPa, under flow of hydrogen gas, with weight hourly space velocity (WHSV) of 4 h −1 . Products are analysed by gas chromatography with mass spectra detector (GC–MS) and by nuclear magnetic resonance (NMR) of 1 H. For the fresh catalyst, all triglyceride was converted to hydrocarbon by the process. For NaZSM5, the catalyst activity is high but has a high decrease over the time of reaction. It was changed for HZSM5, where the catalyst maintained a high activity even after 90 min of reaction. This treatment improved also the product, where a high yield of gaseous hydrocarbon was changed to a high yield of liquid hydrocarbon, especially by the presence of aromatics molecules. [ABSTRACT FROM AUTHOR]

New data were obtained for production of H 2 and reduction of total organic carbon (TOC) by gasification of lactose in supercritical water with(out) the presence of catalysts (NaOH, KOH and Na 2 CO 3 ) in a continuous Inconel 625 flow reactor. The gasification reactions were carried out at 550–700 °C, 22.5 MPa, lactose concentrations in the range of 0.5–2.5 wt%, feed flow rates of 5 and 7 g min −1 and a total reaction time of 30 min. The optimum condition for the production of H 2 yielded approximately 4.5 mol H 2 /mol lactose with a TOC reduction of ∼95%. In addition, supercritical gasification of whey was carried out using the same operating conditions as the lactose system. A reduction of 92% on the TOC and 0.45 molar fraction of H 2 production was achieved, similar to the gasification of lactose at a concentration of 0.5 wt%. [ABSTRACT FROM AUTHOR]

The increasing importance of environmentally friendly processes leads to science in search of new technologies, like the generation of electrical power from hydrogen in fuel cells. Thus, a good alternative for producing hydrogen is ethanol steam reforming, since ethanol comes from a renewable resource. Hydrogen production from ethanol steam reforming was evaluated for the CuNi/CeO 2 and CuNi/Nb 2 O 5 –Na catalysts with and without nitrogen as the carrier gas. For the catalyst supported in ceria, the presence of inert favored the steam reforming reaction with a small increased in the conversion of ethanol. Additionally, the reduction ability of ceria, in the conditions tested, enabled the formation of acetone through the interaction of molecules with the support. For Nb 2 O 5 supported catalyst, the presence of inert showed lower conversion. It happened because filamentous coke the drag with some metal particles, and higher selectivity to H 2 . Coke formation was observed for both catalysts, but only CuNi/Nb 2 O 5 –Na presented sintering. The catalysts presented distinct behaviors, due to their markedly different support characteristics. The presence of N 2 in the reactional system influences expressively the distribution of products and the ethanol conversion for both catalysts tested. The carrier gas can favor the selectivity of H 2 and the ethanol steam reforming reaction, depending on the support used. [ABSTRACT FROM AUTHOR]

Abstract: In this work a thermodynamic analysis of the autothermal reforming (ATR) of methane was performed. Equilibrium calculations employing entropy maximization were performed in a wide range of oxygen to methane mole ratio (O/M), steam to methane ratio (S/M), inlet temperature (IT), and system pressure (P). The main calculated parameters were hydrogen yield, carbon monoxide formation, methane conversion, coke formation, and equilibrium temperature. Further, the optimum operating oxygen to methane feed ratio that maximizes hydrogen production, at P = 1 bar, has been calculated. The nonlinear programming problem applied to the simultaneous chemical and phase equilibrium calculation was implemented in GAMS®, using CONOPT2 solver. The maximum amount of hydrogen obtained was in the order of 3 moles of hydrogen per mole of fed methane at IT = 1000 °C, P = 1 bar, S/M = 5, and O/M = 0.18. Experimental literature data are in good agreement with calculation results obtained through proposed methodology. [Copyright &y& Elsevier]

Abstract: The ethanol oxidative reforming reaction was performed with Ni–Cu catalysts on different supports. The results indicated that Ni–Cu/Nb2O5 and Ni–Cu/ZnO were the most appropriate catalysts for the reaction regarding activity, stability, and selectivity for hydrogen production. Ni–Cu/Nb2O5 catalysts have strong acidity (at 600 °C), while ZnO has very low acidity. Ni–Cu/Ce0.6Zr0.4O2 catalysts, which only have weak acidity (at 250 °C), presented poor stability and hydrogen selectivity. This shows that acidity has no influence on hydrogen production. [Copyright &y& Elsevier]

Abstract: Ni–Cu catalysts supported on different materials were tested in ethanol steam reforming reaction for hydrogen production. These catalysts were evaluated at reaction temperature of 400°C under atmospheric pressure. The reagents, with a water/ethanol molar ratio equal to 10, were fed at 70dm3/(hgcat) (after vaporization). Analysis of the ethanol conversion, as well as evaluation and quantification of the reaction products, indicated the catalyst 10% Ni–1% Cu/Ce0.6Zr0.4O2 as the most appropriate for the ethanol steam reforming under investigated reaction conditions, among the studied catalysts. During 8h of reaction this catalyst presented an average ethanol conversion of 43%, producing a high amount of H2 by steam reforming and by ethanol decomposition and dehydrogenation parallel reactions. Steam reforming, among the observed reactions, was quantified by the presence of carbon dioxide. About 60% of the hydrogen was produced from ethanol steam reforming and 40% from parallel reactions. [Copyright &y& Elsevier]