Volume 2, Issue 4 (2019)                   IQBQ 2019, 2(4): 33-52 | Back to browse issues page

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1- PhD candidate- Tarbiat Modares University , f.gorzin@modares.ac.ir
2- Tarbiat Modares University
3- Catalysis Research Group, Petrochemical Research & Technology Company, National Iranian Petrochemical Company
Abstract:   (7377 Views)
In this study, sonochemical synthesis was used to prepare nanostructured HZSM-5 catalysts. The three most effective ultrasound related variables including ultrasound power, irradiation time, and sonication temperature were investigated. The combined effect of these variables on relative crystallinity and mean crystal size of HZSM-5 nanocatalysts was studied using a central composite design. Higher crystallinity and lower crystal size were obtained by increasing ultrasound power, irradiation time, and sonication temperature while there was an optimum range for mentioned variables. The maximum relative crystallinity and minimum mean crystal size were obtained as 55.51% and 62.37 nm, respectively, under the optimal conditions of ultrasound power (231 W), irradiation time (21.18 min), and sonication temperature (42.68 °C). The results confirmed that sonochemical method considerably increased crysatllinity and reduced crystal size of HZSM-5 nanocatalysts at lower time. Hydrothermal method produced catalyst with full crystallinity and mean crystal size of 893 nm with 120 min aging and 48 h crystallization in autoclave while sonicated HZSM-5 catalyst with 21 min sonication and 4 h crystallization has 55.51% crystllinity and 62.37 nm mean crystal size. On the other hand, no HZSM-5 phase was formed in hydrothermal method with 120 min aging and 4 h crystallization in autoclave. These results strongly suggests that a catalyst with smaller crystal size, higher crystallinity and BET surface area at lower crystallization time can be obtained by using ultrasound instead of aging step in HZSM-5 synthesis
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Article Type: Original Research | Subject: nano-catalyst
Received: 2018/05/25 | Accepted: 2019/03/19 | Published: 2019/03/19

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