A COMPUTERIZED SYSTEM ON KINETIC ANALYSIS AND EVALUATION OF GAS/SOLID REACTIONS

The present paper presents the structure, features and functions of a computerized system on kinetic analysis and evaluation of gas/solid reactions, KinPreGSR. Kin-PreGSR is a menu driven system, can be operated with MS Windows as workbench in a PC computer. It has been developed using visual C++ with FoxPro hybrid coding technique.KinPreGSR combines the characteristics of gas/solid reactions with the kinetic models as well as mass and heat transfer equations. The database files were established for the apparent activation energies of some reduction and decomposition reactions to allow the prediction of the reaction kinetics to some extents. Outputs can be displayed using graphical or numerical forms. Examples regarding the oxide reduction and carbonate decomposition under isothermal conditions are given to show those functions.

Process intensification in gas/liquid/solid reaction in trickle bed reactors: A review

As an important form of reactors for gas/liquid/solid catalytic reaction,trickle bed reactors (TBRs) are widely applied in petroleum industry,biochemical,fine chemical and pharmaceutical industries because of their flexibility,simplicity of operation and high throughput.However,TBRs also show inefficient production and hot pots caused by non-uniform fluid distribution and incomplete wetting of the catalyst,which limit their further application in chemical industry.Also,process intensification in TBRs is necessary as the decrease in quality of processed crude oil,caused by increased exploitation depths,and more restrictive environmental regulations and emission standards for industry,caused by increased environment protection consciousness.In recent years,lots of strategies for process intensification in TBRs have been proposed to improve reaction performance to meet the current and future demands of chemical industry from the environmental and economic perspective.This article summarizes the recent progress in techniques for intensifying gas/liquid/solid reaction in TBRs and application of intensified TBRs in petroleum industry.

Selective oxidation of methane and carbon deposition over Fe_2O_3/Ce_(1-x)Zr_xO_2 oxides

A series of Fe2O3/Al2O3, Fe2O3/CeO2, Ce0.7Zr0.3O2, and Fe2O3/Ce1-xZrxO2（x = 0.1–0.4） oxides was prepared and their physicochemical features were investigated by X-ray diffraction（XRD）, transmission electron microscope（TEM）, and H2-temperature-programmed reduction（H2-TPR） techniques. The gas–solid reactions between these oxides and methane for syngas generation as well as the catalytic performance for selective oxidation of carbon deposition in O2-enriched atmosphere were investigated in detail. The results show that the samples with the presence of Fe2O3show much higher activity for methane oxidation compared with the Ce0.7Zr0.3O2solid solution,while the CeO2-contained samples represent higher CO selectively in methane oxidation than the Fe2O3/Al2O3sample. This suggests that the iron species should be the active sites for methane activation, and the cerium oxides provide the oxygen source for the selective oxidation of the activated methane to syngas during the reaction between methane and Fe2O3/Ce0.7Zr0.3O2. For the oxidation process of the carbon deposition, the CeO2-containing samples show much higher CO selectivity than the Fe2O3/Al2O3sample, which indicates that the cerium species should play a very important role in catalyzing the carbon selective oxidation to CO. The presence of the Ce–Zr–O solid solution could induce the growth direction of the carbonfilament, resulting in a loose contact between the carbon filament and the catalyst. This results in abundant exposed active sites for catalyzing carbon oxidation, strongly improving the oxidation rate of the carbon deposition over this sample. In addition, the Fe2O3/Ce0.7Zr0.3O2also represents much higher selectivity（ca. 97 %） for the conversion of carbon to CO than the Fe2O3/CeO2sample, which can be attributed to the higher concentration of reduced cerium sites on this sample. The increase of the Zr content in the Fe2O3/Ce1-xZrxO2samples could improve the reactivity of the materials for methane oxidation, but it also reduces the selectivity for CO formation.

Activation Energy of Nitriding Medium Carbon Ferromanganese Alloy

Investigation of some kinetics aspects of the reaction between nitrogen and medium carbon ferromanganese （MC-FeMn） was made. Nitriding process of fine medium carbon ferromanganese was carried out at temperature ranging from 973 to 1 223 K and time up to 480 min. Nitriding was carried out under nitrogen and hydrogen gas pressures. At temperature of 573 K, hydrogen gas was injected with pressure of about 0.2 MPa followed by injection of nitrogen gas up to 1.2 MPa. Sample mass was 35 g, nitrided in cylindrical chamber with 34 mm in inner diameter and 1 200 mm in length. The change in nitrogen pressure was taken as an indication for nitrogen pickup. The mass gain i.e. nitrogen pickup in kilograms per surface area （m2） was determined by time at different temperatures. Nitriding rate constants were calculated and the activation energy of nitriding process was derived from Arrhenius equation. The nitriding rate constant was found to be increased by increasing temperature of the reaction. The activation energy of nitriding process of fine medium carbon ferromanganese at time ranging up to 28 800 s is around 140 kJ/mol. It was found that the rate controlling step of the nitriding process of MC-FeMn is diffusion mechanism.