The Fabrication of Ga2O3/ZSM-5 Hollow Fibers for Efficient Catalytic Conversion of n-Butane into Light Olefins and Aromatics

Abstract

Abstract:In this study, the dehydrogenation component of Ga 2 O 3 was introduced into ZSM-5 nanocrystals to prepare Ga 2 O 3 /ZSM-5 hollow fiber-based bifunctional catalysts. The physicochemical features of as-prepared catalysts were characterized by means of XRD, BET, SEM, STEM, NH 3 -TPD, etc., and their performances for the catalytic conversion of n-butane to produce light olefins and aromatics were investigated. The results indicated that a very small amount of gallium can cause a marked enhancement in the catalytic activity of ZSM-5 because of the synergistic effect of the dehydrogenation and aromatization properties of Ga 2 O 3 and the cracking function of ZSM-5. Compared with Ga 2 O 3 /ZSM-5 nanoparticles, the unique hierarchical macro-meso-microporosity of the as-prepared hollow fibers can effectively enlarge the bifunctionality by enhancing the accessibility of active sites and the diffusion. Consequently, Ga 2 O 3 /ZSM-5 hollow fibers show excellent catalytic conversion of n-butane, with the highest yield of light olefins plus aromatics at 600˝C by 87.6%, which is 56.3%, 24.6%, and 13.3% higher than that of ZSM-5, ZSM-5 zeolite fibers, and Ga 2 O 3 /ZSM-5, respectively.

Aromatization over nanosized Ga-containing ZSM-5 zeolites prepared by different methods: Effect of acidity of active Ga species on the catalytic performance

“…The strong acidity of ZSM-5 zeolites promotes coke deposition and leads to deactivation of catalysts. Ga-containing ZSM-5 zeolites are highly efficient bifunctional catalysts for converting olefins to aromatics and have been widely used in propane, LGP and methanol aromatization [9][10][11][12] . The incorporation of gallium into the ZSM-5 zeolite not only reduces the Brønsted acid strength but also results in the formation of additional stronger Lewis acid sites due to the extra-framework Ga species which can improve the rate-determining dehydrogenation step of olefin aromatization.…”

Strategies to Enhance the Catalytic Performance of ZSM-5 Zeolite in Hydrocarbon Cracking: A Review

“…cracking over Ga2O3/ZSM-5 reached to 87.6%, which was 56.3% higher than that over ZSM-5 [65]. Fu et al [66] prepared two zeolites with different morphologies (nano-sphere and nano-rod crystallite aggregation) but with the same acid properties.…”

“…The conversion maintained at about 95% even after reaction for 60 h. Based on this hierarchical ZSM-5 hollow fibers, Ga 2 O 3 /ZSM-5 bifunctional hollow fiber catalyst was prepared and it showed enhanced catalytic activity and light alkene selectivity due to the synergistic effect of the dehydrogenation activity of Ga 2 O 3 and cracking activity of ZSM-5. The highest yield of light olefins plus aromatics of n-butane cracking over Ga 2 O 3 /ZSM-5 reached to 87.6%, which was 56.3% higher than that over ZSM-5 [65]. Fu et al [66] prepared two zeolites with different morphologies (nano-sphere and nano-rod crystallite aggregation) but with the same acid properties.…”

Effect of Ethanol on the Morphology and Textual Properties of ZSM-5 Zeolite

“…The MFI zeolite with ultrathin nanosheet morphology showed a higher BET surface area and pore volume, which facilitated the transport of reactants, resulting in higher activity comparing with the conventional ZSM-5 zeolite [15][16][17]. The ZSM-5 zeolite with a hollow fiber morphology facilitated the cracking of n-butane and the generation of light alkenes due to the hierarchical porosity [18]. The self-stacked MFI zeolite prepared with the assistance of cationic polymers showed high activity in 1,3,5-triisopropylbenzene cracking and methanol-to-olefins reaction [19].…”