Adsorption Equilibrium of Thiophenic Sulfur Compounds on the Cu-BTC Metal-Organic Framework

Thiophenic compounds are the refractory organosulfur compounds remaining in the transportation fuels, and their removal from liquid fuels has become increasingly important. In this work, adsorption isotherms of thiophene (T), benzothiophene (BT), and dibenzothiophene (DBT) in isooctane onto a metal-organic framework (Cu-BTC) were measured for (293.15 to 313.15) K and equilibrium sulfur concentrations up to 370 ppmw-S (ppmw of sulfur). The adsorption capacity followed the order of BT < T < DBT under the investigated sulfur concentrations and temperatures. The adsorption isotherms of T and DBT are highly favorable. The isotherm data were well-correlated using a multitemperature Langmuir model, and three parameters were extracted for each thiophenic compound. The multitemperature Langmuir model has predictive ability for the adsorption of T, BT, and DBT within the sulfur concentration range and the temperature range studied. The heat of adsorption (Delta H) of T, BT, and DBT is (-21.99, -14.23, and -37.34) kJ.mol(-1), respectively. The order of Delta H is in agreement with the adsorption affinities.