The correlation between the iodine value of coconut shell carbon and their reaction performance for NO₂ to NO

Abstract

BackgroundThe precise detection of NO2 requires the conversion of NO2 to NO using a molybdenum conversion furnace. Currently, molybdenum wire is utilized as the conversion agent for the molybdenum furnace; however, the high operating temperature of the molybdenum wire can inadvertently convert NH3 in industrial exhaust gas to NO, potentially impacting the accuracy of the detection process. Consequently, there is a pressing need to develop low‐temperature conversion agents. The study aims to establish a correlation between the iodine value, which characterizes the liquid‐phase adsorption properties of activated carbon, and its capacity for NO2 conversion, with the potential to provide valuable theoretical insights supporting the development of commercial molybdenum furnace conversion agents.ResultsThe iodine value of coconut shell carbon is closely related to their reaction performance for NO2 to NO among three samples with different iodine values. AC‐900, AC‐1200, and AC‐1500 exhibit notable NO2 to NO conversion capabilities. Specifically, AC‐900 demonstrates significantly superior reaction performance compared to AC‐1200 and AC‐1500. Under conditions of 175 °C and 1 L/min, the NO2 conversion rates for AC‐900, AC‐1200, and AC‐1500 are measured at 97.3%, 88.2%, and 86.4%, respectively. Furthermore, the evaluation of AC‐1200 and AC‐1500 at different flow rates at 125 °C reveals a decrease in NO2 conversion with increasing gas flow rate. AC‐1200 exhibits better reaction performance compared to AC‐1500.ConclusionThe structure‐activity relationship between iodine value of coconut shell carbon and their performance for NO2 to NO is revealed. The capacity of activated carbon to convert NO2 is significantly influenced by the presence of oxygen functional groups and the proportion of micropores. The content of micropores and oxygen‐containing functional groups, especially phenolic hydroxyl groups, decreases with the increase of iodine value, leading to a decrease in the reaction performance of the conversion agent.This article is protected by copyright. All rights reserved.