Styrene (ST) is one of the most important feedstocks in the petrochemical industry and must be separated from a mixture of ST and ethylbenzene (EB). While the current technology comprises the energy-intensive vacuum distillation process, energy-saving adsorptive separation can be an alternative for ST/EB separation. The potential of a series of isostructural metal-organic frameworks (MOFs), M-MOF-74 (M = Mg, Co, Cu, or Zn), featured by highly dense unsaturated metal sites were evaluated for use in ST/EB separation using liquid-phase adsorption experiments. While all four M-MOF-74 materials showed selective adsorption of ST over EB, Co-MOF-74 exhibited the highest ST/EB selectivity (6.9) and the largest ST uptake (2.5 mmol/g), which were superior to those of benchmark MOF materials. This can be explained by the preferential interaction between unsaturated Co2+ sites and unsaturated ST molecules. Moreover, Co-MOF-74 retained its adsorption performance, porosity, and structural integrity after three consecutive adsorption and desorption experiments. These findings suggest that creating high density of Co2+ sites within a proper pore size would be an efficient strategy for developing an adsorbent for ST/EB separation.
Bibliographical noteFunding Information:
This work was supported by the “ National Research Foundation of Korea under Grant” (No. NRF-2019R1A2C2002313 ) through the National Research Foundation (NRF) funded by the Ministry of Science and ICT, Republic of Korea . Also, this work was supported by Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20174010201640 )
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Filtration and Separation