MODIFICATION OF ZEOLITE Y EXTERNAL SURFACE USING ORGANOSILANE FOR ENHANCING HYDROPHOBICITY

• Main Author: SUSANTI (NIM:20516008), YUNI
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31841
• Institution: Institut Teknologi Bandung

Zeolite is a crystalline microporous aluminosilicate which consists of tetrahedral <br /> <br /> <br /> <br /> (SiO&#8324; )&#8308; &#8315; and (AlO&#8324; )&#8309; &#8315; as primary building units. The use of zeolite Y for <br /> <br /> <br /> <br /> biomass conversion reaction catalyst in hot liquid water (HLW) phase system <br /> <br /> <br /> <br /> having low thermal stability. In this conditions zeolite lost their crystallinity. <br /> <br /> <br /> <br /> Decreased crystallinity can cause zeolite to lose catalytic function. The stability of <br /> <br /> <br /> <br /> zeolite against HLW is related to zeolite hydrophobicity. Zeolite stability to hot <br /> <br /> <br /> <br /> liquid water related with its hydrophobicity. Increasing the Si/Al ratio is one of <br /> <br /> <br /> <br /> the methods to enhance the hydrophobicity of zeolite, but reduce the Brønsted <br /> <br /> <br /> <br /> acid active site in the zeolite. The reduced site of Brønsted acid can disrupt the <br /> <br /> <br /> <br /> catalytic activity of zeolite. An alternative methode to increase hydrophobicity <br /> <br /> <br /> <br /> without reducing the density of acid sites is by modifying the external surface <br /> <br /> <br /> <br /> zeolite. This research objective was to enhance hydrophobicity properties of <br /> <br /> <br /> <br /> zeolite parent conducted by modifying zeolite external surface using organosilane. <br /> <br /> <br /> <br /> The organosilan used in this study was APTES (aminopropyltriethoxysilane) with <br /> <br /> <br /> <br /> a ratio 0,5 mmol/g zeolite. The reaction was carried out in toluene and stirred for <br /> <br /> <br /> <br /> 24 h at 500 rpm at room temperature. The zeolite was then collected by filtration. <br /> <br /> <br /> <br /> After washing several times with ethanol, zeolite was dried at 100 oC for 24 h. <br /> <br /> <br /> <br /> The modified zeolite sample was labelled as hydrophobic zeolite. While the <br /> <br /> <br /> <br /> unmodified zeolite is named the parent zeolite. Then test the distribution of parent <br /> <br /> <br /> <br /> zeolite and modified zeolite (hydrophobic zeolite) on two phases (water-organic) <br /> <br /> <br /> <br /> and stability test of both zeolites to HLW. HLW treatment is carried out at 200 oC <br /> <br /> <br /> <br /> at a certain time variation. Zeolite distribution on two phases showed that parent <br /> <br /> <br /> <br /> zeolite rapidly settled to the bottom of the aqueous phase, while the hydrophobic <br /> <br /> <br /> <br /> zeolite was dispersed in the organic phase. Stability of zeolite parent and <br /> <br /> <br /> <br /> hydrophobic zeolite to HLW was characterized. XRD patterns analysis showed <br /> <br /> <br /> <br /> that the intensity of zeolite parent was significantly decrease compared with <br /> <br /> <br /> <br /> zeolite hydrophobic. A dramatic drop in diffraction intensity after HLW <br /> <br /> <br /> <br /> treatment, indicating a significant loss of crystallinity. The obtained diffractogram <br /> <br /> <br /> <br /> is used to calculate crystallinity of both zeolites. The crystallinity result that <br /> <br /> <br /> <br /> hydrophobic zeolite Y was more able to maintain crystallinity to HLW treatment <br /> <br /> <br /> <br /> even for 72 hours. While the parent zeolite lost almost 50% of its crystallinity at <br /> <br /> <br /> <br /> the same time. XRF analysis results showed that the Si/Al ratio of zeolite parent <br /> <br /> <br /> <br /> was decreased along with the HLW treatment time. Water molecules attacked <br /> <br /> <br /> <br /> Si&#8308; &#8314; species and hydrolized from zeolite framework affected to the decrease of <br /> <br /> <br /> <br /> Si/Al ratio, while zeolite hydrophobic maintained Si&#8308; &#8314; species in the zeolite <br /> <br /> <br /> <br /> framework. IR spectrum showed the increase of silanol group absorbance in <br /> <br /> <br /> <br /> zeolite parent and not exist in zeolite hydrophobic. The existance of the silanol <br /> <br /> <br /> <br /> group indicated the damage in the zeolite framework. Morphology of zeolite <br /> <br /> <br /> <br /> parent after HLW 10 h treatment indicated the damage of zeolite. The rough <br /> <br /> <br /> <br /> surface confirms the IR result of an excess of silanol groups. TG analysis showed <br /> <br /> <br /> <br /> the percentage of organic compound in zeolite hydrophobic was 7% <br /> <br /> <br /> <br /> approximately both before and after HLW treatment. This indicates that organic <br /> <br /> <br /> <br /> compounds was not lost during HLW treatment. <br />