KINETICS OF GAS-SOLID REACTIONS: PART I: HIGH TEMPERATURE CARBON GASIFICATION. PART II: FERRIC OXIDE CATALYZED SORPTION OF SULFUR DIOXIDE. PART III: CATALYTIC DECOMPOSITION OF NITRATES TO NITROGEN.

摘要

This research deals with gas-solid reactions, such as (1) Carbon gasification reactions (non-catalyzed gas-solid reactions). (Part 1). (2) Desulfurization of flue gases (Catalyzed gas-solid reactions). (Part 2). (3) Dentrification of flue gases (Catalyzed gas-solid reactions). (Part 3).;Catalytic Desulfurization of Flue Gases. A small amount of iron oxide coated on the surface of dolomite particles substantially increases both the reaction rate and the ultimate capacity for sulfur dioxide sorption. Although the iron oxide coating catalyzes the sulfation of Tymochtee dolomite, it has an inhibiting effect on Greer limestone. The interplay of two opposing effects: increase in the chemical rate and a decrease in pore diffusion rate due to pore plugging has been demonstrated by experiments with pellets made from pulverized Greer limestone.;For Tymochtee dolomite, with 1.08% (by weight based on CaO) Fe(,2)O(,3) coated on uncalcined stone, it has been shown, through a model, that for 90% sulfur retention, a 40% reduction of the sorbent requirement can be achieved over the uncatalyzed case.;Catalytic Denitrification of Flue Gases. The two-step approach involves absorption of NO(,x) and O(,2) with a metal or metal oxide forming nitrate, which is followed by decomposition of the nitrate at a higher temperature. This approach may be applied to situations where NO(,x) concentration is very low, such as in combustion gases in power plants. In decomposition of the nitrate, NO is decomposed to N(,2) in the pores of the product layer, where the NO concentration is about 3 orders of magnitude higher than that in combustion gases. The rate of NO decomposition is accordingly raised by several orders of magnitude over that in direct catalytic processes.;Carbon Gasification Reactions. A new technique was developed and used successfully to measure simultaneously the overall rate of reaction and the penetration depth for the C-CO(,2) reaction in the temperature range 1300 C to 1600 C. A simple model has been proposed to calculate the first order reaction rate constant and the pore diffusivity. This model allows for the variation of pore diffusivity in the reaction zone in contrast to previous models by Thiele and Zeldovich.;A model has been proposed to predict the conversion of NO to N(,2) on decomposition of Nitrate/Oxide mixtures.