Removal of naphthalene, phenanthrene, and pyrene by sorbents from hot gas

It is the first time that the removal of polycyclic aromatic hydrocarbons (PAH) containing different aromatic rings number [naphthalene (Np), phenanthrene (Phe), and pyrene (Py)] from combustion hot gas has been carried out. The aim was to relate the sorbents textural characteristics with the adsorption capacity of these 2-4-ring PAH at the conditions emitted at energy generation. The sorbents textural parameters [total micropore volume (VN2), narrow micropore volume (VCO2), mesopore volume (VBJH), and the free active sites] were analyzed trying to correlate them with their Np, Phe, and Py adsorption capacities. To get this aim, single and multiple linear regressions (MLR) were applied to the three PAH. A principal component analysis was performed to generate new and uncorrelated variables. It enabled us to show that the relations between the textural parameters were analyzed using a principal components regression (PCR). The PCR analysis had a good statistical quality, but neither did it allow differentiating free active site types nor did VN2 and VCO2. The correlations were thus set up applying a MLR to the original variables. The regression statistical quality was similar to the PCR analysis, and it could give an easier explanation of the parameters that affected the adsorption. In Np adsorption, the 87% data variance was explained, and the adsorption was positively correlated to VCO2 and the micropore mean diameter (I.). In the Phe regression there was 98% variance explained, and its adsorption was positively correlated to the VN2 and the micropore distribution, n. Finally, in the Py adsorption, the 96% data variance was explained, and this adsorption was positively correlated to VN2 and VBJH. These dependencies were according to the molecular parameters of these compounds (molecular diameter and volatility) because the higher the number of aromatic rings of the PAH, the more favored the adsorbate-adsorbate interactions. Besides, the higher the mean diameter micropores, the lower the diffusional problems showed by Np, Phe, and Py.