Infiltration of Coke and Other Carbons by Pyrolysis of Methane and the Effects on Microstructure and Reactivity

摘要

The reactivity of carbons in oxidizingenvironments is dependent on both the chemistry (e.g.,the presence of catalytic impurities) and themicrostructure (e.g., porosity). In some instances, forexample carbon brake linings for aircraft or blastfurnace cokes, high reactivity is a disadvantage. Thecoke in the blast furnace functions as a structuralmaterial within the burden and its early loss of strength,due to reaction at a point too high in the stack, isdetrimental. Blast furnace operators have long usedstandard laboratory tests ("coke reactivity index" and"coke strength after reaction") in selecting their cokes.The paper describes an ongoing investigation whereincarbon microstructures are modified, to change theirreactivity (and thereby CRI and CSR), by pyrolysis ofmethane within the pores of the carbon or coke. Themethane was a model for natural gas, a hydrocarbon thatmight be sufficiently cheap to make such reactivitychanges economically worthwhile. In the case of eachcarbon the microstructural changes accompanying methanepyrolysis were characterized by mercury porosimetry andgas adsorption measurements. In many instancesresistivities were significantly reduced and thereduction could be explained by changes in the microstructure.