A cobalt catalyst (25%Co/γ-Al2O3, prepared by slurry phase impregnation) was used in a fixed bed reactor under a pressure/density tuned supercritical fluid mixture of n-pentane/nhexane. By using an inert gas as a balancing gas to maintain a constant pressure, the density of the supercritical fluid could be tuned near the supercritical point while maintaining constant space velocity within the r...

The supercritical fluid extraction of essential oil from rosemary leaves and its subsequent impregnation in linear low-density polyethylene (LLDPE) films were studied. effects temperature (318 338 K), pressure (15 25 MPa) particle size (0.9 0.15 mm) on the yield investigated. Impregnation assays developed at two different values (12 20 MPa), (308 328 time (1 5 h). was increased by increasing de...

The nuclear isotropic shielding constants sigma((17)O) and sigma((13)C) of the carbonyl bond of acetone in water at supercritical (P=340.2 atm and T=673 K) and normal water conditions have been studied theoretically using Monte Carlo simulation and quantum mechanics calculations based on the B3LYP6-311++G(2d,2p) method. Statistically uncorrelated configurations have been obtained from Monte Car...

The structure and properties of supercritical water is investigated in relation to the energy and environmental issues of the 21 century. Molecular interpretations are given to the temperature dependence of the hydrogen-bonding structure, dynamics, and chemical reactions of supercritical water. The three-dimensional network structure, characteristic of ambient water, is broken down in hot expan...

A new and economically attractive type of geothermal resource was recently discovered in the Krafla volcanic system, Iceland, consisting of supercritical water at 450 °C immediately above a 2-km deep magma body. Although utilizing such supercritical resources could multiply power production from geothermal wells, the abundance, location and size of similar resources are undefined. Here we prese...

A revised phase diagram for water shows three distinct fluid phases. There is no continuity of liquid and gas, and no “critical point” on Gibbs’ density surface as hypothesized by van der Waals. A supercritical colloidal mesophase bounded by percolation transition loci separates supercritical liquid water and gas-phase steam. The water phase is bounded by a percolation transition (PA) of availa...

With high pressures, supercritical fluids can be studied over a very wide range of density. Fluids with strongly interacting polar molecules for example water are of particular interest. Results for several thermophysical properties are discussed. Density, dielectric constant and self—ionization of water have been determined or predicted to 1000 °C. Beyond 20 GPa very hot water appears to becom...

It is well established that pretreatment of lignocellulosic biomass required to achieve an effective enzymatic saccharification process. At the present time, most touted pre-treatment technologies would cause environmental pollution and unsustainable water use for pretreated material prior saccharification. To address these shortcomings, technology which combines supercritical CO2, SC-CO2 (a gr...

With the exhaustion of fossil fuels and the severe pollution of the environment, it’s urgent to find substitute renewable energy resources. Biomass is a kind of widespread and abundant renewable resource with lower sulfur content than fossil fuels, so the pollution to environment from biomass usage is much slighter than that from fossil fuels usage. Besides, zero emission of CO2 can be realized...

The gasification of an aqueous suspension of lignite from Alexandria coalfield (Ukraine) under the supercritical pressure was studied. The initial rates of the formation of hydrogen, carbon dioxide and methane were evaluated. The mutually stimulating interaction of the components of "brown coal-water-mineral matter" system was shown due to the influence of nanoscaled water medium on the formati...