Geopolymer concrete is a material manufactured by polymerizing sources of aluminates and silicates like fly ash, metakaolin, slag, zeolite, etc. with an alkaline solution. A study has been undertaken to produce lightweight geopolymer concrete by using waste zeolite particles (zeolite molecular sieve) as aluminates and silicates source and at the same time as lightweight medium. In addition, others three geopolymer lightweight concrete mixes were produced by partially replacing the waste zeolite particles (25% of volume) with sources materials (fly ash type F, fly ash type C and waste zeolite powder. Moreover, the impact of this partially replacement on dry density, compressive strength and permeation characteristics of produced geopolymer lightweight mixes was studied. An alkaline solution of sodium silicate and sodium hydroxide was used in all the investigated mixes as an activator. From the findings, a geopolymer lightweight mix suitable for insulation purposes (density of 1610 kg/m3 and 28 days compressive strength of 5.1 MPa) was successfully produced using waste zeolite molecular sieve. It was found also that the lightweight zeolite particles were uniformly distributed through the produced mixes. Finally, it was found that replacement of 25% of volume of zeolite particles by fly ash (type C) helped in not only enhancing the compressive strength by about 13% but also reducing the water absorption by about 33%.
AbstractThe crystalline zeolite, namely faujasite type Y with SiO2/Al2O3 mole ratio of 5 was used as raw material for preparation of isomerization catalysts. Decationized HY-zeolite was prepared by treating Na Y-zeolite with solution of 4N ammonium chloride through ion exchange, drying at 110°C, and calcination initially at 150°C and the temperature increased to 525°C with a rate of 75°C/h to liberate NH3 and water. Then, HY-zeolite was reduced with hydrogen at 380°C, then fabricated as a spherical shape and calcined at 400°C.A 0.5 wt % Pt/HY-zeolite catalyst was prepared by impregnation with chloroplatinic acid. The catalyst was dried at 110°C over night, calcined at 400°C and reduced with hydrogen at 380°C. The prepared catalyst powder was then formulated as a spherical shape with 20% sodium silicate. The decationized HY-zeolite was treated with HCl, HNO3 and HI promoters using different normalities and with different concentrations of Sn, Ni and Ti promoters by impregnation method to obtain acidic and metallic promoters' catalysts, respectively. A 0.5 wt% of Pt was added to above catalysts using impregnation method. The catalysts were then dried, calcined, reduced and formulated using the same steps in preparation of Pt/HY-zeolite catalyst.