Catalytic cracking of n-hexane for producing light olefins on 3D-printed monoliths of MFI and FAU zeolites

摘要

Three dimensional (3D) printing manufacturing has attracted growing interests for material synthesis applied in various fields because of its rapid accomplishment, cost effectiveness, approach facilities and structure controllability. In this work, we present a facile and efficient method for the fabrication of 3D-printed HZSM-5 and HY monoliths with macro-meso-micorporosity as the heterogeneous catalysts for n-hexane cracking reaction. To modify and improve the performance of the monolithic catalysts, the silicoaluminophosphate with chabazite framework (SAPO-34) was grown on the zeolite monolith surface via secondary growth method. Characterization of the catalysts suggest that surface area, porosity, acidity and structure of the catalysts were influenced by both formulation into monolithic structures and growth of SAPO-34. The performance of the 3D-printed monolithic catalysts was investigated in catalytic cracking of n-hexane at 600 and 650 degrees C for 24 h time on stream. Our results indicated that HZSM-5 zeolite monolith exhibits more stable activity in n-hexane cracking and higher selectivity to light olefins than its powder counterpart. A highest selectivity to light olefins (53.0%) was found on HZSM-5 zeolite monolith at 650 degrees C whereas over HY zeolite monolith the highest selectivity was found to be 57.9% at 600 degrees C. SAPO-34 growth enhanced the activity all monolithic catalysts and significantly improved catalytic selectivity to BTX (benzene, toluene and xylene) over HY monoliths. The highest BTX selectivity reached 27.5% on SAPO-34 coated HY monolith at 600 degrees C.