Adsorption of thiophene by activated carbon: A global sensitivity analysis

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The removal of sulfur compounds in biomass gasification processes is crucial to protect downstream equipment. While conventional sorbent materials can retain H2S, many fail to capture heterocyclic sulfur compounds such as thiophene (C4H4S). This work explored activated carbons (ACs) for the removal of thiophene from the gas phase both experimentally and by employing different models. Experiments were performed in a laboratory packed bed column between 100–200°C at various gas flow-rates and inlet concentrations. Altering the temperature had the strongest effect with breakthrough capacities ranging from 7–138mmolkg−1. The transient adsorption process was described by a 1-D approach, including mass transfer phenomena and axial dispersion. Experimental validation showed good agreement between measured and predicted breakthrough times and capacities. A global sensitivity analysis (GSA) was performed to obtain a ranking of importance of model input factors and gain further process insight. The GSA included 12 model parameters and a selection of axial dispersion correlations and isotherm models. Based on the chosen range of input factors, the GSA indicated that the type of isotherm model, axial dispersion correlation, and temperature have a major effect on the predicted breakthrough time. The calculated slope of the curve is strongly affected by the isotherm model and axial dispersion correlation. Overall, this work showed that ACs are a promising option for thiophene removal and provided a generic approach for the application of GSA to adsorption models. In the given context the analysis demonstrated that the selection of common model assumptions deserves as much attention as the model parameters.