Preparation of 5A zeolite monolith granular extrudates using kaolin: Investigation of the effect of binder on sieving/adsorption properties using a mixture of linear and branched paraffin hydrocarbons

摘要

5A zeolite monolith extrudates using kaolin is synthesized,and effect of binders on sieving/adsorption properties of the prepared zeolite is reported.The monolith extrudates of 4A zeolite powder produced as the precursor of 5A zeolite in the first stage of synthesis process was prepared using different percentages of kaolin powder and carboxymethylcellulose(CMC)as binding agent.The average particle size distribution of produced 4A zeolite was between 20 and 40 US standard mesh sizes equivalent to 0.841 mm and 0.420 mm,respectively.The extrudate was calcined at 600 °C,and the kaolin content of extrudates was converted to type A zeolite through ion exchange by immersing the extrudates in caustic soda solution.The 4A zeolite extrudate samples were converted to 5A type through ion exchange process using calcium chloride solution.The 5A zeolite samples were characterized using XRD,SEM,and EDX instrumental analytic methods.Sieving test was carried out using samples of 5A zeolite and a special cut of kerosene containing C_(10)-C_(13)saturated hydrocarbons using a simple dead-end fixed bed.Results show that the highest purity of 5A zeolite,highest rate of calcium ion exchange,and best sieving results are obtained when 30 wt% of binder(kaolin)is used,and use of small amounts of CMC as an organic binder along with inorganic kaolin binder has a profound effect on the adsorption properties of the synthesized 5A zeolite.This profound effect is attributed to de-clogging of the cylindrical pores due to CMC gasification in final calcinations of the extrudates.