Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the chall...Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the challenging separation ofα-olefin/paraffin is achieved through energy-saving ways,for which adsorption separation is an attractive technology.One of the most significant differences between the adsorption separation of long-chain and light hydrocarbons is the steric hindrance of the molecular chain.Herein,we propose a combination of window size,metal node spacing,and bending degree to quantitatively describe the adsorption cavity structure for the separation of long-chainα-olefin/paraffin.The general cavity structural characteristics of microporous materials with good separation performance for long-chainα-olefin/paraffin are revealed.The selective adsorption of liquid C6 and C_(8)α-olefin/paraffin mixtures on CuBTC(BTC=benzene-1,3,5-tricarboxylate)was studied in detail to reveal the influence of the cavity structure on the adsorption and interaction using a combination of batch adsorption experiments and molecular simulation techniques.CuBTC exhibited 360 and 366 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins,respectively.The adsorption energies were−0.540 and−0.338 eV for C8 linearα-olefin and paraffin,respectively.The contributions of different types of interactions to the overall adsorption energy were quantified to illustrate the adsorption energy difference betweenα-olefin/paraffin and CuBTC.This work provides a new understanding of the long-chain hydrocarbon adsorption behavior different from ethylene/ethane and propylene/propane,which guides the design of adsorbents forα-olefin/paraffin separation.展开更多
The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-ch...The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-chainα-olefin/paraffin is achieved.Adsorption separation is an efficient alternative to energy-intensive distillation.Herein,the selective adsorption behavior and interaction mechanism of liquidα-olefin/paraffin on Mg metal–organic framework(MOF)-74 were investigated using a combination of batch adsorption experiments and molecular simulation techniques.Mg-MOF-74 exhibited 301 and 333 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins in binary olefin/paraffin mixtures,respectively,and was still unsaturated at high olefin concentrations.The adsorption isotherms were analyzed and compared with the simulated results by configurational-bias grand canonical Monte Carlo(CB-GCMC)simulation.The visualized adsorption sites by CB-GCMC simulation indicated that all adsorbates were arranged in hexagonal shapes and preferentially adsorbed by the vertex of the hexagon,where the metal node magnesium is located.The adsorption energies were−1.456 and−0.378 eV for C8 linearα-olefin and paraffin,respectively,calculated by density functional theory simulation based on the visualized adsorption sites.The charge transfer was analyzed,and the contributions of different kinds of interactions to the overall adsorption energy were quantified by principle orbital interaction analysis to further reveal the difference in adsorption energy betweenα-olefin/paraffin and Mg-MOF-74.This work also provides a general means to investigate the liquid adsorption performance and host–guest interactions in the adsorption or catalytic processes of nanoporous materials.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21878169 and 21991102)the National Key Research and Development Program of China(No.2019YFA0905100)the Tsinghua University Initiative Scientific Research Program(No.2018Z05JZY010).
文摘Long-chainα-olefins have a high added value as important raw materials for many highly marketable products.Fishcher-Tropsch synthesis products contain ultrahigh-contentα-olefins,which are of great value if the challenging separation ofα-olefin/paraffin is achieved through energy-saving ways,for which adsorption separation is an attractive technology.One of the most significant differences between the adsorption separation of long-chain and light hydrocarbons is the steric hindrance of the molecular chain.Herein,we propose a combination of window size,metal node spacing,and bending degree to quantitatively describe the adsorption cavity structure for the separation of long-chainα-olefin/paraffin.The general cavity structural characteristics of microporous materials with good separation performance for long-chainα-olefin/paraffin are revealed.The selective adsorption of liquid C6 and C_(8)α-olefin/paraffin mixtures on CuBTC(BTC=benzene-1,3,5-tricarboxylate)was studied in detail to reveal the influence of the cavity structure on the adsorption and interaction using a combination of batch adsorption experiments and molecular simulation techniques.CuBTC exhibited 360 and 366 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins,respectively.The adsorption energies were−0.540 and−0.338 eV for C8 linearα-olefin and paraffin,respectively.The contributions of different types of interactions to the overall adsorption energy were quantified to illustrate the adsorption energy difference betweenα-olefin/paraffin and CuBTC.This work provides a new understanding of the long-chain hydrocarbon adsorption behavior different from ethylene/ethane and propylene/propane,which guides the design of adsorbents forα-olefin/paraffin separation.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21878169 and 21991102)Key Technologies Research and Development Program of China(No.2019YFA0905100)Tsinghua University Initiative Scientific Research Program(No.2018Z05JZY010).
文摘The liquid products of Fischer–Tropsch synthesis with a high content of linearα-olefins can act as valuable raw materials for increasing high added-valueα-olefin production if the challenging separation of long-chainα-olefin/paraffin is achieved.Adsorption separation is an efficient alternative to energy-intensive distillation.Herein,the selective adsorption behavior and interaction mechanism of liquidα-olefin/paraffin on Mg metal–organic framework(MOF)-74 were investigated using a combination of batch adsorption experiments and molecular simulation techniques.Mg-MOF-74 exhibited 301 and 333 mg/g olefin adsorption capacities for C6 and C8 linearα-olefins in binary olefin/paraffin mixtures,respectively,and was still unsaturated at high olefin concentrations.The adsorption isotherms were analyzed and compared with the simulated results by configurational-bias grand canonical Monte Carlo(CB-GCMC)simulation.The visualized adsorption sites by CB-GCMC simulation indicated that all adsorbates were arranged in hexagonal shapes and preferentially adsorbed by the vertex of the hexagon,where the metal node magnesium is located.The adsorption energies were−1.456 and−0.378 eV for C8 linearα-olefin and paraffin,respectively,calculated by density functional theory simulation based on the visualized adsorption sites.The charge transfer was analyzed,and the contributions of different kinds of interactions to the overall adsorption energy were quantified by principle orbital interaction analysis to further reveal the difference in adsorption energy betweenα-olefin/paraffin and Mg-MOF-74.This work also provides a general means to investigate the liquid adsorption performance and host–guest interactions in the adsorption or catalytic processes of nanoporous materials.
