Isolated cationic Pd species encapsulated in MFI zeolite,i.e.,Pd@MFI,have been successfully prepared via in situ hydrothermal route followed by oxidative treatment.The as-prepared Pd@MFI samples are investigated as pr...Isolated cationic Pd species encapsulated in MFI zeolite,i.e.,Pd@MFI,have been successfully prepared via in situ hydrothermal route followed by oxidative treatment.The as-prepared Pd@MFI samples are investigated as promising catalysts in the reaction of methane combustion.Typically,Pd@H-ZSM-5 shows remarkable activity in methane catalytic combustion with a low apparent activation energy value of 70.7 kj/mol as well as good catalytic stability even in excess water vapor.Detailed characterization results demonstrate the strong interaction between Pd sites and zeolite framework in Pd@ZSM-5 and the efficient stabilization of isolated Pd sites by zeolite thereof.Spectroscopy analyses reveal that the presence of BrΦnsted acid sites is beneficial to methane adsorption and its subsequent activation on adjacent Pd sites,constructing cooperation between Bronsted acid sites and Pd sites within the confined space of MFI zeolite toward high-efficiency methane catalytic combustion.The reaction mechanism of methane combustion catalyzed by Pd@H-ZSM-5 model catalyst is finally discussed.展开更多
A series of Co-imbedded zeolite-based catalysts were synthesized following a facile solvent-free grinding route.The catalytic performance for direct syngas conversion to gasoline range hydrocarbons was compared with t...A series of Co-imbedded zeolite-based catalysts were synthesized following a facile solvent-free grinding route.The catalytic performance for direct syngas conversion to gasoline range hydrocarbons was compared with their counterpart Co-impregnated zeolite-based catalysts.Successful transformation of solid raw materials to targeted zeolite was confirmed by XRD,SEM,STEM,and N2 physisorption analysis.An in-depth study of acidic strength and acidic site distribution was conducted by NH3-TPD and Py-IR spectroscopy.Acidic strength showed a pivotal role in defining product range.Co@S1,with the weakest acidic strength of silicalite-1 among three types of zeolites,evaded over-cracking of product and exhibited the highest gasoline and isoparaffin selectivity(≈70%and 30.7%,respectively).Moreover,the solvent-free raw material grinding route for zeolite synthesis accompanies several advantages like the elimination of production of wastewater,high product yield within confined crystallization space,and elimination of safety concerns regarding high pressure due to the absence of the solvent.Facileness and easiness of the solvent-free synthesis route together with promising catalytic performance strongly support its application on the industrial scale.展开更多
文摘Isolated cationic Pd species encapsulated in MFI zeolite,i.e.,Pd@MFI,have been successfully prepared via in situ hydrothermal route followed by oxidative treatment.The as-prepared Pd@MFI samples are investigated as promising catalysts in the reaction of methane combustion.Typically,Pd@H-ZSM-5 shows remarkable activity in methane catalytic combustion with a low apparent activation energy value of 70.7 kj/mol as well as good catalytic stability even in excess water vapor.Detailed characterization results demonstrate the strong interaction between Pd sites and zeolite framework in Pd@ZSM-5 and the efficient stabilization of isolated Pd sites by zeolite thereof.Spectroscopy analyses reveal that the presence of BrΦnsted acid sites is beneficial to methane adsorption and its subsequent activation on adjacent Pd sites,constructing cooperation between Bronsted acid sites and Pd sites within the confined space of MFI zeolite toward high-efficiency methane catalytic combustion.The reaction mechanism of methane combustion catalyzed by Pd@H-ZSM-5 model catalyst is finally discussed.
基金the financial support from the Zhejiang Province Natural Science Foundation(LY19B060001)the Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(2018-K25)the Foundation of Zhejiang University of Science and Technology(2019QN18,2019QN23)~~
文摘A series of Co-imbedded zeolite-based catalysts were synthesized following a facile solvent-free grinding route.The catalytic performance for direct syngas conversion to gasoline range hydrocarbons was compared with their counterpart Co-impregnated zeolite-based catalysts.Successful transformation of solid raw materials to targeted zeolite was confirmed by XRD,SEM,STEM,and N2 physisorption analysis.An in-depth study of acidic strength and acidic site distribution was conducted by NH3-TPD and Py-IR spectroscopy.Acidic strength showed a pivotal role in defining product range.Co@S1,with the weakest acidic strength of silicalite-1 among three types of zeolites,evaded over-cracking of product and exhibited the highest gasoline and isoparaffin selectivity(≈70%and 30.7%,respectively).Moreover,the solvent-free raw material grinding route for zeolite synthesis accompanies several advantages like the elimination of production of wastewater,high product yield within confined crystallization space,and elimination of safety concerns regarding high pressure due to the absence of the solvent.Facileness and easiness of the solvent-free synthesis route together with promising catalytic performance strongly support its application on the industrial scale.
