Preparation And Performance Study Of Hybrid Proton-electron Conductor Ceramic Hydrogen Permeable Membrane

In recent years,energy demand has continued to grow rapidly,especially the large consumption of fossil energy.The burning of fossil energy not only destroys the ecological environment,but also inevitably depletes resources.Therefore,clean-renewable hydrogen energy is an ideal energy source.And researches and development goals are increasingly focused on advanced hydrogen production and separation technologies all around the world.The proton-electronic ceramic hydrogen permeable membrane theoretically has 100%selectivity to hydrogen,good mechanical properties and low cost.These advantages make it an ideal technology for the separation and purification of hydrogen,attracting more and more researchers to study it.Therefore,this thesis selects mixed proton-electronic conductor ceramic materials as research objects.Then the phase structure,micromorphology and hydrogen permeation properties of perovskite-type,lanthanum-tungstate-type,and perovskite-lanthanum-tungstate dual-phase-type materials were investigated.First,a series of Ba_1-xZr_0.1Ce_0.7Y_0.2O_3-??x=-0.05,0,0.05??abbreviated as BZCY095,BZCY,and BZCY105?powders were prepared by the traditional solid-phase reaction method.And the sheet-shaped hydrogen permeable membranes were made by isostatic pressing.The effects of non-stoichiometric Ba on the properties of the materials were also studied.The results show that excess Ba has a beneficial effect on the formation of phase structure and sintering.And the oxygen vacancy concentration in Ba_1-x-x Zr_0.1Ce_0.7Y_0.2O_3-?increases with the increase of Ba content,the hydrogen permeation flux also increases.Finally,we proposed:In Ba_1-xZr_0.1Ce_0.7Y_0.2O_3-?,when Ba is excessive,excess Ba may occupy Ce sites to form more oxygen vacancies;when Ba is insufficient,Y replaces Ba sites to reduce oxygen vacancies.Oxygen vacancies promote the increase of hydrogen permeation flux.Then,La_5.5W_1-xCr_x O_11.25-??x=0.1⁰.4??abbreviated as LWCr01,LWCr02,LWCr03,LWCr04?powders were synthesized by the solid-phase reaction method.And the sheet-shaped hydrogen permeable membranes were made by isostatic pressing.The effects of Cr doping on the phase structure,hydrogen permeation and stability were also studied.With a small amount of Cr doping,LWCr01 forms a lanthanum tungstate single phase.When Cr content increases,the residual La₂O₃affects the hydrogen permeation flux of the membrane material.At 950°C,the hydrogen permeation flux of the LWCr02 membrane is 1.5 times higher than that of the undoped LWO membrane,which is related to the high content of Cr⁶⁺in LWCr02.Moreover,the permeation flux of LWCr02remained stable during the 104-hour hydrogen permeation test.And the phase structure remained and the membrane was free of defects,indicating that LWCr02 has good stability in the hydrogen atmosphere.Finally,a series of different volume ratios La_5.5W_0.6Mo_0.4O_11.25-?-BaZr_0.1Ce_0.7Y_0.2O_3-??abbreviated as LWM04-BZCY=7:3?vol?,LWM04-BZCY=5:5?vol?and LWM04-BZCY=3:7?vol??dual-phase ceramic materials were successfully synthesized by the traditional solid-phase reaction method.And the sheet-shaped hydrogen permeable membranes were made by isostatic pressing.Their compatibility,distribution and hydrogen permeability also were studied.The LWM04-BZCY dual-phase membranes obtained the biphasic coexisting without any reaction between the two phases after sintering at 1400°C for 10h.Under the dry condition,the hydrogen permeation flux of the LWM04-BZCY=7:3?vol?membrane improved compared to the single-phase LWM04,reaching 0.1269mL/min·cm² at 1000°C.In addition,the hydrogen permeation flux of the LWM04-BZCY=7:3?vol?membrane reached 0.1418mL/min·cm² at 1000°C after adding water on the sweeping side.The dual-phase structure remained after hydrogen permeation,which proves that the LWM04-BZCY membrane has good stability in the test atmosphere at high temperatures.