Poster Presentation

¹Samira Farajfaed ; ²Neda Asasian-Kolur; ³Seyedmehdi Sharifian

¹Department of Chemical Engineering, Fouman Faculty of Engineering, College of Engineering, University of Tehran

²Chemical Engineering Department, Fouman Faculty of Engineering, College of Engineering, University of Tehran,Fouman, Iran

³Chemical Engineering Department, Fouman Faculty of Engineering, College of Engineering, University of Tehran, Fouman, Iran

Clay materials are considered as primary matrices for adsorbents, catalysts, and photocatalysts preparation, due to their low cost, availability, and lateral and relatively porous network. In the present work, modification of clay's structure with silica and zirconium has been studied. Silica is known as one of the pillaring agents that increases clay's surface area by creating some pillars in the interlayer spaces. On the other hand, zirconium's catalytic activity is also established because incorporating Zr into the clay structure increases the density of acid sites generating Brönsted-type acidity and enhances thermal and mechanical stability. Therefore, Si/Zr modified clays can be used as adsorbents, catalysts, and catalyst supports. Three different procedures have been presented and applied to prepare Si/Zr modified clays in the present work. All methods were based on adding a surfactant (HDTMA)-containing solution to the clay suspension and TEOS to generate a Silica structure inside the clay. ZrOCl2 was also applied to introduce zirconium in the structure of clay. Despite using an equal amount of zirconium salt in all samples' preparation, modified clays with various contents of zirconium were prepared due to different procedures. This study aims to investigate and compare the structure of these Si/Zr-clays. The Physical and chemical properties of the samples were characterized by powder x-ray diffraction (XRD), x-ray fluorescence (XRF), N2 adsorption-desorption isotherms (BET), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR). It was found that depending on the ZrOCl2 addition step to the process; synthesized samples contained different amounts of Zr in their structure from 2.1 to 44.6 %wt. Modification with silica led to an increase in the specific surface area from 45 to 477 m2/g; however, by adding Zr content, due to the placement of zirconium particles in the interlayer space of the samples, a reduced surface area and mesoporous structure were obtained. Although, the formation of amorphous SiO2 and ZrO2 particles reduced the initial clay's crystallinity; the clay layer structure was preserved to some extent during the modification steps.

Clay; Silica modification; Zr incorporation; Acidity; Catalyst