The methylation of 2-methylnaphthalene （2-MN） into 2,6-dimethylnaphthalene （2,6-DMN） was investigated over the solid acid catalysts. The results show that HZSM-5 modified by NH4F has better catalytic performance t...The methylation of 2-methylnaphthalene （2-MN） into 2,6-dimethylnaphthalene （2,6-DMN） was investigated over the solid acid catalysts. The results show that HZSM-5 modified by NH4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity. When NH4F/HZSM-5 is further modified by SrO, its catalytic activity decreases due to the decrease in the total acid amount and acidic strength. As a result, the comprehensive modification of NH4F and SrO leads to the inere, ase in the 2,6- DMN selectivity （2,6-DMN to DMN）, up to 64.8% when 2-MN conversion is 10%. We calculated the ESP charge by density functional theory and the results show that the 6-position in 2-MN has higher ESP charge value than 7-position. The formation of 2,6-DMN is favored energetically as compared to that for 2,7-DMN. This suggests during the alkylation of 2-MN inside the ZSM-5 channel, the formation of 2,6-DMN is favored electronically than that of 2,7-DMN. Hence, lowering the acidity of catalyst is a key factor to obtain high selectivity of 2,6-DMN.展开更多
The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the foll...The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the following supports: SBA-15（2-D structure）, TUD-1（3-D sponge-like structure） and fumed silica HS-5（3-D disordered structure）. Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol（PEG） was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS（after PEI loading） play a more important role in the COsorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher COsorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica（HS-5） based MBS showed the highest COsorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiOparticles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for COand the stronger temperature dependence of COcapacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the COsorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.展开更多
文摘The methylation of 2-methylnaphthalene （2-MN） into 2,6-dimethylnaphthalene （2,6-DMN） was investigated over the solid acid catalysts. The results show that HZSM-5 modified by NH4F has better catalytic performance than parent HZSM-5 due to the decrease in the acidity. When NH4F/HZSM-5 is further modified by SrO, its catalytic activity decreases due to the decrease in the total acid amount and acidic strength. As a result, the comprehensive modification of NH4F and SrO leads to the inere, ase in the 2,6- DMN selectivity （2,6-DMN to DMN）, up to 64.8% when 2-MN conversion is 10%. We calculated the ESP charge by density functional theory and the results show that the 6-position in 2-MN has higher ESP charge value than 7-position. The formation of 2,6-DMN is favored energetically as compared to that for 2,7-DMN. This suggests during the alkylation of 2-MN inside the ZSM-5 channel, the formation of 2,6-DMN is favored electronically than that of 2,7-DMN. Hence, lowering the acidity of catalyst is a key factor to obtain high selectivity of 2,6-DMN.
基金the support of this work at Penn State by the U.S.Department of Energy,National Energy Technology Laboratorythe financial support by the China Scholarship Council,the Natural Science Foundation of China(No.51176034)the Open Fund of Key Laboratory of Coal-Based CO2 Capture and Geological Storage of Jiangsu Province(2016A05)
文摘The objective of this work is to study the influences of silica supports and PEG additive on the sorption performance of molecular basket sorbent（MBS） for COcapture consisting of polyethylenimine and one of the following supports: SBA-15（2-D structure）, TUD-1（3-D sponge-like structure） and fumed silica HS-5（3-D disordered structure）. Effects of the supports regarding pore structures and pore properties, the PEI loading amount as well as the sorption temperature were examined. Furthermore, polyethylene glycol（PEG） was introduced as an additive into the sorbents and its effect was investigated at different PEI loadings and sorption temperatures. The results suggest that the pore properties of MBS（after PEI loading） play a more important role in the COsorption capacity, rather than those of the supports alone.MBS with 3D pore structure exhibits higher COsorption capacity and amine efficiency than those with 2D-structured support. Among the sorbents studied, fumed silica（HS-5） based MBS showed the highest COsorption capacity in the temperature range of 30-95 °C, probably due to its unique interstitial pores formed by the aggregation of polymer-loaded SiOparticles. It was found that the temperature dependence is directly related to the PEI surface coverage layers. The more PEI surface coverage layers, the higher diffusion barrier for COand the stronger temperature dependence of COcapacity. 3D MBS exceeds 2D MBS at the same PEI coverage layers due to lower diffusion barrier. Adding PEG can significantly enhance the COsorption capacity and improve amine efficiency of all MBS, most likely by alleviating the diffusion barrier within PEI bulk layers through the inter-molecular interaction between PEI and PEG.
