Effect of Nitrogen, Carbon Dioxide, and Air Activation on the Low-Temperature Ammonia Removal Performance of Activated Carbon during Nitric Oxide Removal

Abstract

To investigate the effect of gas activation on the low-temperature ammonia removal performance of activated carbon during nitric oxide (NO) removal, nitrogen (N2), carbon dioxide (CO2), and air were used as activated gases. Orthogonal experiments were designed to examine the activation conditions of each factor. The influence of various activation conditions on the physicochemical properties of activated carbon has been investigated. The interaction between various factors and their effect on the NH3 removal performance of NO were thoroughly investigated. Results show smooth pore walls and large average pore size after N2 activation. Moreover, some nitrogen-containing functional groups are introduced to the surface and help improve the NO conversion rate. CO2 activation can readily disrupt pore structures, causing surface pores to become disordered and some lignin and other functional groups to decompose; thus, the NO conversion rate by the activated carbon following CO2 activation is low. The strong oxidation of air activation causes the pore wall of activated carbon to collapse, the formation of new pores on the surface, and the introduction of oxygen-containing functional groups, so that the denitration rate increases with increasing activation temperature. The kind of activated gas has the most significant effect on the NO removal performance of activated carbon, while the activation temperature has minimal effect on the NO conversion rate of activated carbon. N2 activation at 225°C for 60 min is the best physical activation condition. Herein, we focused on three factors: activation gas; activation temperature; and activation time, which influence the nitric oxide conversion rate of activated carbon. Further, the effect of these factors and their interactions on nitric oxide removal performance were studied. Relevant research findings can be utilized as a reference for the physical activation of activated carbon and optimization of the low-temperature NH3 removal performance of activated carbon during nitric oxide removal.