Study On Preparation And Properties Of Ca-based Dechlorination

With the development of the catalytic reforming,more and more hydrogen chloride is produced in this section,which has a negligible impact on the production operation and environment.This paper prepared Ca-based dechlorination sorbents of dry process dechlorination by coprecipitation method.Using orthogonal experiment,single factor experiment and different temperature treatment to explore and optimize process conditions of the preparation procedure about AlCa-based dechlorination sorbents.Then,we determinated chlorine capacity by the evaluation system of homemade dechlorination performance evaluation to find optimization technics parameters.On this basis,Zn,Cu or Fe are added by control variate method,analysis of the influence of different metallic element or additive quantity on the AlCa-based dechlorination sorbents' chlorine capacity.The samples were characterized by TG-DTG,BET/BJH,XRD,SEM.Studied of various process conditions and add factors on the impact of the sample,the dechlorination process and mechanism were discussed in the end.(1)The following conclusions were obtained by orthogonal experiment and single factor experiment,the best AlCa-based dechlorination sorbent has the 23.22% dechlorination capacity and it prepared under 45? preparative reaction temperature,the molar ratio of Al to Ca at 1:0.7 and the molar ratio of Al-Ca to precipitant that is NH4HCO3 at 1:0.8.The major factor about dechlorination capacity is preparative reaction temperature,secondary factors are the molar ratio of Al to Ca and Al-Ca to precipitant molar ratio,precipitant is minimal impact.Characterization analysis showed that temperature factors lead to the sample pore structure change is obvious,peaked at 45? and sharply reduced to 85?.(2)Temperature treatment demonstrate that samples with 80? vacuum treatment,which could make dechlorination capacity up to 26.00%.Characterization showed that 80 ?vacuum treatment also make samples have better pore structure,and samples will sintering and collapse at 950?.With the increase of temperature,the samples will have the process ofdehydration,decompose,crystallization.(3)It shows us by evaluating chlorine capacity of three-component dechlorination that if third component was added,chlorine capacity of the samples will be raise,especially added zinc samples.The chlorine capacity could be up to 38.15% by adding Zinc,which was better than ET dechlorinations.Zinc aluminum carbonate hydroxide hydrate could occur when added Zn in a high proportion,more over we find layer structure appeared in this case.Copper element could a slight decrease pore structure and specific surface area,iron element could greatly minish samples pore structure.At last,we studied on HCl diffusion in the dechlorination,the results showed us that internal diffusion conform to Knudsen diffusion model,diffusion coefficient and average pore diameter were positively correlated.