An induction-coupled plasma reactor was used to thermally decompose polypropylene into propylene and other useful chemicals. From a series of statistically designed experiments, it was found that plasma power input, sheath gas flow rate, central gas flow rate, powder feed rate, quench gas flow rate, and interaction of sheath gas flow rate with power and feed rate were the key parameters affecting the yield of monomer in the product gas stream. On average, 78 wt % of the polymer was converted into gas at a power level of 20 kVA. The product gas stream, on an argon-free basis, contained 94% propylene, with the balance being methane, ethylene, and some C 4 's. Transmission electron microscopic analysis of the carbon residue indicated the formation of some novel carbon structures, including carbon nanotubes.

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Pentosan hydrolysis at low aqueous liquid-to-biomass ratios (2.5-15 mL/g) with sulfuric acid as the catalyst is studied in the temperature range of 125-155 degrees C. To facilitate heat transfer and mixing a second insoluble oil is added to the reaction mixture. It is found that even at high slurry concentrations, the reaction is the rate-controlling step. In addition, such systems give higher pentosan yields compared with dilute slurry systems. This is explained using the concept of acid loading which is defined as the acid present per unit mass of biomass.

A mathematical model of a through-circulation packed bed dryer is presented in this paper. The semitheontical model treats the case of constant rate drying in a deep bed of granular solids under initially uniform drying conditions. Experimental data for drying in superheated steam, mixtures of superheated steam and air, and air alone showed good agreement with predictions of the model.Based on t k model, a static optimization method is developed for optimal operation of a continuais through-circulation dryer subject to the inequality constraints of maximum permissible air-horsepower per unit bed area and maximum permissible local find moisture content in tk bed. A nonlinear capacity function is defined in terms of the independent drying variables and is maximized under the above nonlinear restraints.Wilde and Beightler (1) have recently described an Optimization technique, the differential algorithm, which seems particularly suited to the highly nonlinear problem of optimizing a through-circulation dryer. These dryers are desiped for the handling of particulate solids such as granulations, extrusions, etc., in the form of a packed bed. The bed is supported on a perforated plate or screen which is conveyed through the dryer (Figure 1 ) . An appropriate drying agent (hot air, superheated vapor, etc.) is circulated through the bed, usually by centrifugal fans. The dryer may be compartmentalized with each section having its own fan and capable of directing flow through the bed either upward or downward. The effective dryer length is made up by connecting one or more compartments in series. In the case of an existing dryer for which the thermodynamic state of the drying fluid is fixed, the drying time is a function of the fluid velocity, bed loading, and the particle characteristics.The conveyor speed, which is established by the drying time in a given dryer, need not be considered in the analysis. DRYING MODELFor purposes of analysis, the through-circulation dryer can be treated as a packed bed operating under the following conditions: adiabatic drying throughout the bed, plug flow of the fluid, uniform radial temperature distribution in the fluid, uniform and constant particle temperature distribution in the bed, uniform bed voidage, constant gas-solid heat transfer coefficient, and constant fluid transport properties.For the constant rate drying period, the fluid temperature and bed moisture content distribution equations are sufficient to describe the process. These may be obtained from solutions of the difFerentia1 ecergy equation for the gas phase and the coupled differential mass balance equation for the solid phase.Differential energy equation (gas phase)Subject to boundary conditions on moisture content and gas temperature, the solutions in dimensionless form are Gas-phase temperature distributionSolid-phase moisture content distributionThe volumetric heat transfer coefficient for the bed isFor a given value of 2. Equation (4) describes the local drying curve. When axial mixing can be considered negligible, E...

The decomposition of kerogen of Green River formation oil shale, impregnated with transition metals, was investigated following nonisothermal thermogravimetric techniques, in the presence of hydrogen at atmospheric pressure. Experimental data were best fit by a first-order kinetic model with respect to kerogen. The effects of ambient atmosphere and heating rate were also investigated. In the absence of metals, inert and reducing atmospheres were found not to affect kinetic parameters. The frequency factor was found to increase with heating rate at a constant activation energy. The presence of metals in the oil shale matrix and hydrogen in the retorting atmosphere did not alter the kinetic order of kerogen decomposition, but it lowered apparent activation energies and increased the rate constants. These results are discussed in terms of dissociative hydrogen adsorption on the metal crystallites and hydrogen spill over to the organic matter, resulting in hydrogenation and/or cracking reactions.