Energy consumption and carbon dioxide emissions in rail and road freight transport in Spain: a case study of car carriers and bulk petrochemicals

This article provides a new methodology for estimating fuel consumption and emissions by enabling a correct comparison between freight transportation modes. The approach is developed and integrated as a part of an intelligent transportation system dealing with goods movement. A key issue is related to energy consumption ratios and consequent CO2 emissions. Energy consumption ratios are often used based on transport demand. However, including other ratios based on transport supply can be useful. Furthermore, it is important to indicate which factors are associated with variations in energy consumption and emissions; especially of interest are parameters that have a higher incidence and order of magnitude, in order to fairly compare and understand the difference between transport modes and sub-modes. The study finds that the use of an energy consumption equation can improve the quality of the estimates. The study proposes that coefficients that define the energy consumption equation should be tested to determine market niches and sources of improvement in energy consumption according to the category of vehicles, fuel types used, and classes of products transported

Synthesis and characterization of packed mesoporous tungsteno-silicates: application to the catalytic dehydrogenation of 2-propanol

The synthesis of highly ordered mesoporous tungsteno-silicas in which a high percentage of tungsten is introduced into a silica framework is reported hereafter. Powder XRD and TEM have been used to characterize the materials synthesized at room temperature. The materials are shown to be homogeneous as there is no evidence for any crystalline species other than the silica framework. The pore diameter and the surface area of the materials, evaluated from the nitrogen adsorption isotherms and unit cell parameter indicate a pore diameter of about 2 nm and a surface area of 1400 m(2) g(-1) for a content of 10% tungsten. Catalyzed dehydration of 2-propanol has been investigated and the activity of the materials synthesized is significant, even for low tungsten content W-MCM-41 materials. (C) 2003 Elsevier B.V. All rights reserved

Synthèse de zircones mésoporeuses de haute surface

Il est montré que des oxydes de zirconium mésoporeux et de haute surface spécifique peuvent être préparés à partir de l'hydrolyse de ZrOCl2 8 H2O, en présence de tensioactif (CTAB). Les hautes aires spécifiques sont attribuées à la formation de clusters agrégés sous la forme de petites particules. Le temps de réaction est le paramètre qui paraît gouverner l'obtention des hautes aires spécifiques ainsi que la structure cristalline des matériaux calcinés. Un mécanisme de synthèse prenant en compte ces différents paramètres et conduisant à la formation d'oxydes de zirconium divisés est proposé

Synthesis of hexagonally packed porous titanium oxo-phosphate

The synthesis of a hexagonally packed porous titanium oxo-phosphate from titanium isopropoxide, sulfuric acid and alkyltrimethylammonium bromide is reported. XRD and TEM have been used to characterize the mesostructure that forms at ambient temperature as well as the calcined material. The effect of the alkyl chain length of the surfactant has also been studied. The N2-sorption isotherms of the samples calcined at 350°C are characteristic of super-microporous materials. The pore diameters and the surface areas of the materials, evaluated from the N2-sorption isotherms and unit cell parameters, indicate pore diameters of about 2–3 nm and surface areas around 350 m2/g

Influence of the particle size of Cu-ZSM-5 for the heterogeneous oxidation of bulky hydrocarbons

Diffusion limitations inducing pores blocking is a key para- meter when using heterogeneous catalysts. The aim of this work is to study the influence of the particle size and therefore, the external surface extent, on catalytic properties of ZSM-5 crystals. Nanocrystals or microcrystals of Cu-ZSM-5 were prepared and characterized. The key difference between these catalysts is the extent of external active surface, favouring the nanocrystal form of ZSM-5. Both materials were further employed for the catalytic oxidation of various substrates differing by their size. Oxidation of indane, tetralin, propyl and octylbenzene was successfully performed when using both catalysts. However, a clear enhancement was observed when the nanocrystal form of Cu-ZSM-5 was used. The different efficiency of both catalysts was discussed in terms of external active surface and diffusion limitations

An experimental study of the state of hexane in a confined geometry

International audienc

Sorption of water–ethanol mixtures by poplar wood: swelling and viscoelastic behaviour

International audienceThe swelling of wood upon impregnation by aqueous solutions of organic solvents is larger than swelling by pure water. This phenomenon, described as “hyperswelling”, results from specific interactions with components of the complex wood microstructure. To understand the combined effect of mixed solvents on wood properties, the specific influence of each solvent on wood biopolymers and structure must be first characterized. In this study, the effect of the impregnation of aqueous solutions of ethanol with concentrations from 0 to 100% on the physico-mechanical properties of poplar wood was investigated. For each solution, the sorption behaviour of veneer sapwood samples and the effect of sorption on wood viscoelasticity and microstructure were measured through vapour sorption gravimetry, dynamic mechanical analysis and optical microscopy monitoring. Pure water and pure ethanol showed contrasting sorption behaviour, ethanol leading to a much lower swelling and a very limited softening compared to water, despite comparable sorbed amounts. This result suggests different affinities of water and ethanol for biopolymers within wood microstructure. With mixed solutions, larger swelling and stronger variations in viscoelastic behaviour than in pure solvents were observed, confirming the synergistic effect of water/ethanol mixtures on structure and properties of wood cells. Microscopic observations evidenced that ethanol, both alone and in aqueous solutions, generates intercellular decohesion and disbonding of the different wood cell wall layers. These observations are consistent with a mechanism of partial solubilization by ethanol of lignin-related phenolic. This could lead to a release of the constraints which limit the swelling of the polysaccharide fraction of the cell wall by water. Such phenomenon is likely to be at the origin of the hyperswelling observed in mixed water/organic solvent systems