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Adsorption/desorption kinetics and breakthrough of gaseous toluene for modified microporous-mesoporous UiO-66 metal organic framework

Zhang, Xiaodong, Yang, Yang, Lv, Xutian, Wang, Yuxin, Liu, Ning, Chen, Dan, Cui, Lifeng
Journal of hazardous materials 2019 v.366 pp. 140-150
adsorption, coordination polymers, desorption, heat, mass transfer, relative humidity, sorption isotherms, temperature, thermal stability, toluene, vapors
In this work, micro-mesoporous UiO-66 was successfully prepared with P123 (EO20PO70EO20) as structure-directing agent by a simple solvothermal method. Adsorption/desorption kinetics of gaseous toluene over pristine UiO-66 and micro-mesoporous UiO-66 were investigated by breakthrough experiments, toluene vapor adsorption isotherm measurements and temperature programmed desorption (TPD) experiments. The interactions between toluene and UiO-66 samples were assessed through the Henry’s law constant (KH) and the isosteric adsorption heat (ΔHads). The micro-mesoporous UiO-66 crystal demonstrated 2.6 times toluene adsorption capacity of the pristine UiO-66 when the P123/Zr4+ molar ratio was 0.2. Results showed that micropore adsorption was the main adsorption process and the larger pores in micro-mesoporous UiO-66 increased molecular diffusion rate and reduced the mass transfer resistance. This result indicated that micro-mesoporous structures and defect sites had a positive effect on toluene molecules capture. The breakthrough times and the working capacities decreased with the increase of the relative humidity and adsorption temperature. A good thermal stability and reproducibility were revealed over the micro-mesoporous UiO-66 in this paper.