SYNTHESIS OF TRIMODAL HIERARCHICAL POROUS ZSM-5 AT LOW TEMPERATURE AS DIFFUSION BARRIER-FREE CATALYST
ZSM-5 is one of the most widely used zeolite types in industry as a catalyst for petroleum cracking, alkylation, and oil refining. However, ZSM-5 has only one type of porosity, namely micropores (5.3 × 5.6 Å and 5.5 × 5.1 Å) thus creating a diffusion barrier problem where the reactants cannot access...
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| Format: | Final Project |
| Language: | Indonesia |
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| Online Access: | https://digilib.itb.ac.id/gdl/view/65055 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | ZSM-5 is one of the most widely used zeolite types in industry as a catalyst for petroleum cracking, alkylation, and oil refining. However, ZSM-5 has only one type of porosity, namely micropores (5.3 × 5.6 Å and 5.5 × 5.1 Å) thus creating a diffusion barrier problem where the reactants cannot access the zeolite active site and/or the product molecules cannot diffuse out of the pore. In order to overcome the diffusion problem, larger porosity (mesopore (2-50 nm) and/or macroporous (>50 nm)) need to be added to the zeolite framework. Zeolites with more than one type of porosity are called hierarchically porous zeolite (HPZ). In general, HPZ only has two types of porosity (micro/meso or micro/macro), but to increase the catalytic activity of zeolite, it is better if the zeolite has three types of pores at once (micro/meso/macro, trimodal). In this study, trimodal hierarchical porous ZSM-5 was synthesized at a low temperature of 90 °C. This synthesis used tetrapropilammonium bromide (TPABr) as an organic structure directing agent (OSDA) and polydialyldimethylammonium chloride (polyDADMAC) as a macroporogen. ZSM-5 was successfully synthesized with a heating time of 4 days with an optimal polyDADMAC/SiO2 mass ratio of 0.015. ZSM-5 appears to have additional pores, namely mesopores with sizes of 2-4 nm and 7-12 nm and the presence of aggregates of small crystals in the TEM samples. The mass ratio of polyDADMAC/SiO2 which is more than 0.015 can inhibit the crystallization process of ZSM-5 because it is suspected that TPABr competes with polyDADMAC to form mesopores. The results of the catalytic activity test on the cracking of low density polyethylene (LDPE) with a trimodal porous ZSM-5 catalyst (Eobs = 134.247 kJ/mol) is lower than conventional ZSM-5 (Eobs = 336.268 kJ/mol) and ZSM-5 bimodal hierarchical porous (Eobs = 173.556 kJ/mol). |
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