Pengukuran Termogravimetri Secara Non Isotermal Untuk Analisis Kinetika Gasifikasi Kokas

Eventhough a microbalance is an experimentally convenient, widely used method of measuring the gasification rates of carbonaceous materials, problems arise in the interpretation of the measurements. Expressing the change of sample weight with time as a single measure, such as reactivity, has not been standarized The present study utilized an improved analytical technique for calculating the kinetic parameters from coke gasification data. The kinetics of coke gasification were investigated using Thermogravimetry Analyzer (TGA) in the range 25 to 800°C at atmospheric pressure. The activation energy appears to depend linearly on conversion up to 0.5 conversion level and then the activation energy remains constant at 23 kcaUgmole

Periodic operation of catalytic reactors - introduction and overview

A review, with 89 refs., is presented on the subject of periodic operation of catalytic reactors by compn. forcing. Possible objectives of this mode of reactor operation are increased conversion, improved selectivity, reduced catalyst deactivation and insight into mechanisms of reactor models. Several forcing strategies may be used: manipulating one or more reactant concns., or interspersing pulses of inerts between pulses of reactants. These strategies are distinct from the variables in periodic operation, i.e., frequency, wave shape, amplitude, and phase lag. Lab.-scale equipment for periodic forcing makes use of single reactors along with the control of reactant and/or diluent flows. On an industrial scale, two catalyst beds are used, each operating with different feeds under different conditions. Catalyst transfers between the beds. A large literature has developed over the 25 yr since periodic operation was first proposed. [on SciFinder (R)

Periodic operation of catalytic reactors—introduction and overview

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Behaviour of Catalytic Oxidation of Dilute Combustible Gas in a Jacketed Fixed Bed Reactor Under Flow Reversal Process.

An experimental study of the catalytic oxidation of combustible gas in air has been made under flow reversal operation. The experiments were done using a three-zone reactor consisting of two beds packed with an inert having high heat capacity solid placed at both ends of a bed packed with catalyst. The catalyst bed was cooled by passing a fluid through a jacket surrounding the bed. The influence of the operating parameters upon the shape of temperature profiles, percent conversion and heat removal through the coolant were studied. The experiments showed that the maximum measured reactor temperature and heat removal were insensitive to changes in cycle duration and initial temperature but sensitive to feed flow rate and changes in reactant concentration. Key word: catalytic reactor, Stationary cycling Stat

Nonm Adiabatic Catalytic Combustion Of carbon Monoxide Using Flow Reversal

An experimental study of non-adiabatic fixed bed reactor for controlling CO gas has been made under flow reversal operation. Temperature measurements have been made within the catalyst and packing beds. The influence of the operating parameters upon the shape of temperature profiles, conversion and heat removal were studied. The experiments showed that the maximum measured reactor temperature and heat removal are rather insensitive to changes in cycle durationsensitivity was shown to the feed flow rate and reactant concentratio

Loading and draining of periodically operated trickle bed reactor

ABSTRACT Periodic interruption of liquid flow in cocurrent trickle beds appears to be an attractive mode of operation. For modelling these intermittent flow reactors, loading and draining times must be known. Experiments were undertaken using beds of activated carbon with water and air as the fluid phases. Loading time was taken as water brealarough. The gas flow was continuous while the time between the end of drainage and the start of filling was varied to simulate different periods. Drainage experiments followed the liquid flow leaving the bed as a function of time. Liquid hold ups were determined after the filling and draining measurements. Variable considered were particle size, gas and liquid velocities. Loading closely follows the plug flow modeldrainage shows tailing but does not follow literature models. Static and dynamic hold ups at zero gas flow agree with literature correlations for the larger particle size used. A gas velocity effect on both static and dynamic hold up was observed

Scaling Parameters for Dynamic Diffusion-Reaction over Porous Catalysts

The effect of diffusion resistance in porous solid catalysts on reaction rate during periodic cycling of CO concentration is shown for CO oxidation over Pt/Al2O3 by numerical simulation. At some cycling frequencies, the average reaction rate during cycling is higher than the steady-state rate at the mean CO concentration, as expected for this nonlinear, reactant-inhibited reaction. In order to identify major aspects of dynamic diffusion-reaction behavior, a simple kinetic mechanism that shows the main features of CO oxidation and other reactions with significant inhibition by reactants is investigated. A single dimensionless parameter group, the dynamic diffusion coefficient, is added when going from steady-state to unsteady-state diffusion-reaction equations. In the dynamic diffusion coefficient, the rate at which the gas-phase reactant diffuses is reduced by the surface adsorption capacity of the catalyst. The frequency at which the peak average rate occurs is controlled by the dynamic diffusion coefficient