Characteristics And Mechanism In The Woody Activated Carbon Spontaneous Combustion Processing

Activated carbon is an organic macromolecules made by a variety of functional groupsand chemical bonds. The activated carbon has self-heating properties, when the accumulationof heat exceeded that emitted; the activated carbon becomes spontaneous combustion.Spontaneous combustion of activated carbon is a complicated process.In this paper, the effect of volatile, ash, water and functional groups, and other factors hasbeen studied in the spontaneous combustion of activated carbon. And a method thatspontaneous combustion tendency of activated carbon divided by using activation energy indexhas been established.1This paper studied the pyrolysis of3kinds of woody activated carbon bytemperature-programmed, which have different amount of volatile, and the tail gases weredetected on-line. The laws of gases were investigated. It found that, woody activated carbonwould give off H₂, CO, C₂H₄and C₂H₂during the temperature-programmed process ofoxidation, when the woody activated carbon has high volatile; the indicator gases may includeCH₄. When the temperature of reaction system reached100℃,the sample released H₂; with thetemperature raising, C₂H₄, CH₄, CO and C₂H₂were detected respectively at140℃¹60℃,170℃,160℃¹80℃and190℃²00℃;the amount of indicator gases increasing withthe temperature of reaction system raising, however the amount of C₂H₂reached maximum atthe temperature230℃. The indicator gases were released gradually corresponding with theactivation process of functional groups, and provided the energy for the next activationprocess.2This paper studied the pyrolysis of4kinds of powder activated carbon bytemperature-programmed, which have different amount of Fe, and the tail gases were detectedon-line. TG thermal analysis technology was applied to study the4kinds of. The result showsthat: the powder activated carbon which contains more Fe releases combustible gas earlier and more combustible gas; the main stage reaction of the powder activated carbon which containsmore Fe takes place at a lower temperature,so Fe plays a catalytic role in the spontaneouscombustion of powder activated carbon. It is instructive for the study of the spontaneouscombustion of powder activated carbon.3Prepared activated carbon samples contain different moisture,using DSC analysis. Thecritical moisture of activated carbon spontaneous combustion is about12%.4. Activated carbon spontaneous combustion is primarily influenced by activated carbonstructure and environmental factors. If particle size and surrounding conditions are certain,activated carbon structure becomes main factor influencing spontaneous combustion. Therefore,spontaneous combustion propensity can be studied through analyzing activated carbonstructure. The samples are analyzed by means of FT-IR and surface chemical analysis categoryand quantity of the functional groups are got. According to thermogravity analysis andself-ignition experiment the different of spontaneous combustion tendency is determined. Theresult proved that oxidation begins from some active groups readily to be oxidized in theactivated carbon. The higher the content of the active groups, the more easily the spontaneouscombustion propensity of activated carbon. So the method that is feasible.5Thermogravity analysis technique was used to study the course of thermal oxidizingdecomposition from30℃to900℃for the activated carbon. The result suggested that thefast—pyroysis process including the oxidizing decomposition of activated carbon can bedescribed as a first-order chemistry reaction and Coats-Redfern method, thus activation energycan be got. The spontaneous combustion experiment of proved the activated carbon which haslower activation energy would be easy to spontaneous combustion. So spontaneous combustiontendency of activated carbon is divided by using activation energy index.