Green Synthesis Of Chabazite And Its Adsorption Properties Of CO₂/N₂

Nowadays people are putting more and more attentions on greenhouse effect which has caused many serious environmental problems like the occurring of extreme weather,the melting glaciers,the rising of the sea horizon and the land desertification.All those problems make the Greenhouse Effect becoming an urgent global environmental problem.One of the best choice to solve the GHE problem is to reduce the emission of CO₂,and the CO₂ absorption and separation technology would help with it.So the sorbent become a research hotspot as it’s the hard core of the CO₂ absorption and separation technology.chabazite is a fine CO₂ sorbent,however,the previous method to synthesize it often need to use the organic raw materials and organic templates.This thesis aims to do a research on environment friendly synthesis process of chabazite.In this thesis,two methods which called alkali hydrothermal synthesis method and seeding method were made to synthesize chabazite.The best conditions of the synthesis process have been studied,and the characterization and CO₂/N2 absorption and separation property were also studied.The study on best conditions of the synthesis process shows that an alkali/materials ratio at 2.5,stirring time at 30 min,aging time at 60 min,crystallization temperature at 95℃ and crystallization time at 4 d condition can lead to the best sample via Alkali hydrothermal synthesis method,a stirring time at 30 min,aging time at 60 min,crystallization temperature at 95℃crystallization time at 4 d and seed ratio at 20%can lead to the best sample via Seed synthesis method.The XRD analysis,FIRT analysis,TG analysis and SEM analysis shows that both methods can synthesize chabazite well cause a typical structure of chabazite have been found and both samples have good thermal stability.The study on sorbents’ CO₂ absorption shows that both samples have a good absorption property.The adsorption process accords with the Bangham kinetic model.The study shows that the factor that influences the speed of absorption is the diffusion within the channel.Adsorption isotherm analysis shows that both samples adsorption isotherm were isothermal adsorption line type Ⅰ,which put an evidence that chabazite has a micropore structure.The adsorption procedure matches Toth isothermal adsorption model quite well,which shows that the adsorption procedure is a heterogeneous adsorption.Both samples show a high selective adsorption on CO₂/N2,and shows a good prospection on fuel gas CO₂/N2 adsorption and separation.In particular,the synthesis of chabazite by alkali melt hydrothermal method has a CO₂/N2 selectivity greater than 20,which is much higher than that of currently used zeolites such as 13X.Finally,a cyclic CO₂ adsorption research on samples is studied.The calculation shows that difference between two samples are less than 1%,which indicates that both samples synthesized by two methods have a good cyclicadsorbability.