An in situ ATR-IR spectroscopy study of aluminas under aqueous phase reforming conditions.

High temperature/pressure in situ Attenuated Total Reflection Infrared (ATR-IR) spectroscopy was used to investigate the phase transformation of support γ-Al2O3 into boehmite (AlO(OH)) under the hydrothermal conditions of aqueous phase reforming (APR). Activation energy barriers of boehmite formation in hot compressed water at temperatures between 150 and 180 °C were calculated to be 15.9 ± 4.8 kJ mol(-1) for γ-Al2O3 and 43.2 ± 4.3 kJ mol(-1) for Pt/γ-Al2O3. The influence of Pt particles is suggested to slow down the phase transformation by selective blockage of the surface nucleation sites. The presence of ethylene glycol has also an inhibiting effect on the transformation due to the carbon deposits formed on the oxide surface. Post-mortem analysis using Raman spectroscopy, (1)H and (27)Al MAS NMR confirms the formation of boehmite.

Conversion of lignocellulosic biomass to green fuel oil over sodium based catalysts.

Upgrading of biomass pyrolysis vapors over 20 wt.% Na2CO3/γ-Al2O3 catalyst was studied in a lab-scale fix-bed reactor at 500°C. Characterization of the catalyst using SEM and XRD has shown that sodium carbonate is well-dispersed on the support γ-Al2O3. TGA and (23)Na MAS NMR suggested the formation of new hydrated sodium phase, which is likely responsible for the high activity of the catalyst. Catalytic oil has much lower oxygen content (12.3 wt.%) compared to non-catalytic oil (42.1 wt.%). This comes together with a tremendous increase in the energy density (37 compared to 19 MJ kg(-1)). Decarboxylation of carboxylic acids was favoured on the catalyst, resulting to an oil almost neutral (TAN=3.8mg KOH/g oil and pH=6.5). However, the mentioned decarboxylation resulted in the formation of carbonyls, which correlates to low stability of the oil. Catalytic pyrolysis results in a bio-oil which resembles a fossil fuel oil in its properties.

In situ catalytic pyrolysis of lignocellulose using alkali-modified amorphous silica alumina.

Canadian pinewood was pyrolyzed at 450 °C in an Infrared oven and the pyrolysis vapors were converted by passing through a catalyst bed at 450 °C. The catalysts studied were amorphous silica alumina (ASA) containing alkali metal or alkaline earth metal species including Na, K, Cs, Mg and Ca. The catalysts effectiveness to reduce the bio-oil oxygen content, to enhance the bio-oil energy density and to change the liquid and gas product distribution were evaluated using different techniques including gravimetric analysis, elemental analysis, Karl-Fischer titration, GC/MS and micro-GC analysis. According to the results K/ASA found to be the most effective catalysts for conversion of hollocellulose (hemicellulose and cellulose)-derived vapors of pinewood while Cs/ASA catalyst was the most effective catalyst for conversion of lignin-derived vapors and production of hydrocarbons.

Wettability of carbon nanofiber layers on nickel foils.

Carbon nanofiber (CNF) layers have been directly synthesized on nickel foils by chemical vapor deposition at 450°C using different H(2) concentrations and reaction times. The addition of 5% H(2) produces thicker, rougher and more porous CNF layers than when 1% H(2) is used. The roughness and porosity increases with reaction time when 5%, 10% or 20% H(2) are used; however, this effect is less pronounced when 1% H(2) is used. CNFs are 50-55 nm in diameter and have a fishbone type structure. We have studied the influence of CNF layer thickness, porosity and surface roughness on the interaction with water by measuring the contact angle. The water wetting properties of the samples are more significantly influenced by the CNF layer thickness than both surface roughness and porosity. When the CNF layer is thicker than ca. 20 µm, the surface is hydrophobic and the contact angle increases with surface roughness and porosity. When the CNF layer is thinner than ca. 20 µm, the surface is hydrophilic and the contact angle decreases with increasing surface roughness and porosity. This behavior is attributed to penetration of water, making contact with the hydrophilic C layer between the CNF layer and the foil.

Pesticide residues variability and acute dietary risk assessment: a consumer perspective.

In relation to residue variability and acute dietary intake, this paper considers whether or not consumers are adequately protected, and makes recommendations for governments and international bodies. Existing risk assessment science is inadequate to lay to rest some concerns raised by the scientific community, and it is plausible that acute exposures to pesticides from the most contaminated food may be causing adverse effects in some consumers. Consumers International recommends that: (1) analysis and regulation of pesticides with a common mechanism of action (e.g. organophosphate insecticides) be conducted in an integrated, aggregated manner, not on a single pesticide basis; (2) exposure to pesticides in foods consumed in large amounts by children be reduced by revising good agricultural practices; (3) clear risk assessment policies for acute risk assessments be established at the national and international level; and (4) an additional safety factor be applied in order to protect children when establishing maximum residue limits (MRLs) for pesticides in the absence of reliable data on the effects of pesticides on children (e.g. no pesticide-specific tests on immature animals for effects on the developing brain, endocrine, or immune systems).