Synthesis and characterization of hierarchical ZSM-5 zeolite using various templates as cracking catalysts

摘要

Attempt to hydrothermally synthesize hierarchical ZSM-5 zeolites (ZSM-5_h) through double template method has been carried out. In order to develop the structure of microporous ZSM-5 zeolite (ZSM-5_m), three different structure directing agents were used, i.e. TPAOH (t), ethylenediamine (en), and triethylenetetramine (teta), followed by dimethyl dialyl ammonium chloride acrylamide copolymer as mesopore directing agent. All samples were characterized using XRD, BET Surface Area Analyzer, and SEM. XRD pattern of ZSM-5_h/t showed the characteristic peaks of ZSM-5 at position 2θ of 7-9° and 22-25°. Otherwise, the XRD pattern of ZSM-5_h/en and ZSM-5_h/teta showed very weak peaks, indicating that ZSM-5 were not well formed. Nitrogen adsorption of ZSM-5_h/t exhibited hysteresis loop at P/P° 0.7-0.9 indicating the presence of hierarchical mesoporous. SEM images of ZSM-5_h/t showed the characteristic of ZSM-5 which was hexagonal shape. Afterward, H/ZSM-5_h/t zeolite was prepared through ion exchange-treatment using 1 M ammonium nitrate solution, followed by calcination at 823 K to remove all ammonia and produced H/ZSM-5_h/t. This sample was further characterized using XRD and FTIR to observe its acidity. Preliminary test on H/ZSM-5_h/t as catalyst in cracking of n-hexadecane was conducted. As comparison, microporous ZSM-5_m was synthesized and tested under the same conditions to study the effect of different pore size on its activity in catalytic cracking of n-hexadecane. The result showed that ZSM-5_h/t delivered higher conversion than ZSM-5_m, 37.23 and 17.9 in % moles, respectively. It can be concluded that ZSM-5_h was more effective to be used in catalytic cracking of n-hexadecane.