The remediation of carbon dioxide emitted into the atmosphere has become the topic of the day due to the enormous contribution of CO 2 to the devastating global warming. The Boudouard reaction, in which solid carbon (char) reacts with CO 2 to produce carbon monoxide (CO 2 (g)+C(s)↔CO (g)), is a straightforward route for the CO 2 emission mitigation. Through this reaction, the CO 2 coming from variety of combustion plants, including exhaust/flue gas and synthesis gas, can be upgraded to the fuel gas, CO. This work presents a review on the CO 2 gasification of char, from coal, biomass, municipal solid wastes, sewage sludge or any co-utilized blend of them, to produce CO through the Boudouard reaction. An outline of the most effective parameters on the char gasification rate is presented. The parameters which affect the char reactivity are reviewed as those related to the char and its structural features (surface area and porosity, active sites, mineral content, structural evolution of char during gasification, pyrolysis condition and carbon source) and operation parameters (use of catalyst, gasification temperature, gasification pressure and CO 2 partial pressure, char particle size and gasification heat source). The kinetics of the char gasification reaction is studied and several theoretical or semi-empirical kinetic models used to interpret the reaction rate data and calculation of kinetic parameters, specifically activation energy, are reviewed and discussed.

Conversion of the greenhouse gas CO2 to the fuel gas CO via the Boudouard reaction: A review

https://hal.archives-ouvertes.fr/hal-01632394/document

A review of catalysts for the gasification of biomass char, with some reference to coal

CO2 gasification reactivity of biomass char: catalytic influence of alkali, alkaline earth and transition metal salts.

Study on CO2 gasification reactivity and physical characteristics of biomass, petroleum coke and coal chars

Reaction kinetics and mass transfer studies of biomass char gasification with CO2

There are relatively few studies reported in the literature characterizing the kinetics of high-pressure, high-temperature char gasification reactions. Of particular interest to the application of kinetic data to gasification models are studies that provide links between reaction rate data relevant to high-temperature conditions, where some extent of pore diffusion limitation may apply, and lower-temperature, intrinsic gasification reactivity data. This work describes the effects of temperature, reactant partial pressure, and total pressure on the kinetics of the char−CO2 reaction under conditions where reactant diffusion through the pores of the reacting char has been shown to impact the overall conversion rate. A global nth-order rate equation was used to describe these kinetics, in particular, the effect of temperature (via the activation energy) and reactant pressure (via the reaction order). As expected, activation energies at high temperatures (≥∼1300 K) were consistently less than those obtained un...

Kinetics of Char Gasification with CO2 under Regime II Conditions: Effects of Temperature, Reactant, and Total Pressure

The reaction rates of coal chars with CO2 is an important aspect of coal performance under gasification conditions. Most studies of the char−CO2 reaction are undertaken at temperatures (typically ∼1200 K or below) significantly lower than those found in entrained flow applications, to allow detailed investigations into the surface reaction processes. Application of these data to high temperatures therefore requires consideration of how these reaction rates are affected by gas diffusion through the pore structure of reacting particles, yet there are very few char−CO2 rate data at high temperatures and pressures against which such applications can be tested or verified. This paper presents results of measurements of the char−CO2 reaction rate at high pressures (2.0 MPa) and high temperatures (up to 1673 K) using an entrained-flow reactor and also presents analyses of the morphology of the chars sampled during reaction. Using an effectiveness-factor-based approach, the effects of pore-diffusion and surface r...

Elizabeth. M. Hodge

Papers

Kinetics of Char Gasification with CO2 under Regime II Conditions: Effects of Temperature, Reactant, and Total Pressure

The Significance of Char Morphology to the Analysis of High-Temperature Char−CO2 Reaction Rates†