A bidisperse model for transient diffusion and adsorption processes in porous materials is presented in this paper.The mathematical model is solved by numerical methods based on finite elements combined with the linea...A bidisperse model for transient diffusion and adsorption processes in porous materials is presented in this paper.The mathematical model is solved by numerical methods based on finite elements combined with the linear driving force approximation.A criterion based on the model to identify the diffusion controlling mechanism(macropore diffusion,micropore diffusion,or both)is proposed.The effects of different adsorption isotherms(linear,Freundlich,or Langmuir)on the concentration profiles and on curves of fractional uptake versus time are investigated.In addition,the influences of model parameters concerning the pore networks on the fractional uptake are studied as well.展开更多
Internal diffusion of molecules in porous materials plays an important role in many chemical processes.However,the pore diffusion capacity of porous materials cannot be measured by conventional catalyst characterizati...Internal diffusion of molecules in porous materials plays an important role in many chemical processes.However,the pore diffusion capacity of porous materials cannot be measured by conventional catalyst characterization methods.In the present paper,a pore diffusion factor,the ratio of the diffusionconstriction factor to the pore tortuosity of the porous materials,was proposed to measure the diffusion ability of pores inside solid materials,and a method was proposed for measuring the diffusion factor using a well-defined and uniform pore size material as a reference.The diffusion factor was calculated based on the effective diffusion coefficients and the diffusion-constriction factor and pore tortuosity of the reference porous materials.The pore diffusion factor measurement can be performed at room temperature and atmospheric pressure.The pore diffusion factor of conventional porous materials was found to be much smaller than 1,indicating that there is a lot of room for improving the diffusion ability of the conventional catalysts and adsorbents,and could be significantly increased through adding small number of fibers into the conventional porous materials as template.展开更多
基金financial support by the National Natural Science Foundation of China(Grant No.91534120)China National Petroleum Company under the contract number DQZX-KY-17-019
文摘A bidisperse model for transient diffusion and adsorption processes in porous materials is presented in this paper.The mathematical model is solved by numerical methods based on finite elements combined with the linear driving force approximation.A criterion based on the model to identify the diffusion controlling mechanism(macropore diffusion,micropore diffusion,or both)is proposed.The effects of different adsorption isotherms(linear,Freundlich,or Langmuir)on the concentration profiles and on curves of fractional uptake versus time are investigated.In addition,the influences of model parameters concerning the pore networks on the fractional uptake are studied as well.
基金supported by the National Nature Science Foundation of China(Grant No:91534120)。
文摘Internal diffusion of molecules in porous materials plays an important role in many chemical processes.However,the pore diffusion capacity of porous materials cannot be measured by conventional catalyst characterization methods.In the present paper,a pore diffusion factor,the ratio of the diffusionconstriction factor to the pore tortuosity of the porous materials,was proposed to measure the diffusion ability of pores inside solid materials,and a method was proposed for measuring the diffusion factor using a well-defined and uniform pore size material as a reference.The diffusion factor was calculated based on the effective diffusion coefficients and the diffusion-constriction factor and pore tortuosity of the reference porous materials.The pore diffusion factor measurement can be performed at room temperature and atmospheric pressure.The pore diffusion factor of conventional porous materials was found to be much smaller than 1,indicating that there is a lot of room for improving the diffusion ability of the conventional catalysts and adsorbents,and could be significantly increased through adding small number of fibers into the conventional porous materials as template.
