Enhanced light olefins production via n-pentane cracking using modified MFI catalysts

• Published in: Heliyon 2022-03, Vol.8 (3), p.e09181-e09181, Article e09181
• Main Authors: Qureshi, Ziyauddin S., Arudra, Palani, Bari Siddiqui, M.A., Aitani, Abdullah M., Tanimu, Gazali, Alasiri, Hassan
• Format: Article
• Language: English
• Subjects: Catalytic cracking; Ethylene; n-pentane; Olefins; Phosphorous-modified MFI; Propylene
• ISSN: 2405-8440; 2405-8440
• DOI: 10.1016/j.heliyon.2022.e09181

n-pentane catalytic cracking was studied over a series of MFI zeolites with varying SiO2/Al2O3 ratios (30, 80, 280, 500, and 1500) using a fixed-bed reactor operated at temperature 550–650 °C. Other MFI zeolites (SiO2/Al2O3 = 280) with various crystal morphology and size (such as large crystal and nano size) were also synthesized and tested for n-pentane cracking. The effects of MFI zeolite modification with ammonia and phosphorus on its physiochemical properties and catalytic activity were investigated. Among the parent MFI zeolites, MFI (280) demonstrated high selectivity (51%) towards light olefins (C3=/C2= = 0.7) at 650 °C with undesired C1–C4 alkanes (38%). Surface modified MFI (280) zeolites of different crystal size and morphology showed improvement towards propylene selectivity by suppressing undesired reactions. Phosphorous-modified MFI zeolite with a large crystal size was found to improve light olefin selectivity (52.2%) with C3=/C2= = ∼1.3 and reduce undesired C1–C4 alkanes (8%) formation due to suppressed strong acidic sites. The characterization and evaluation results for the modified MFI (280) revealed that the incorporation of phosphorous created moderate acidic sites, which were stabilized by some non-framework aluminum species, thereby leading to suppressing the formation of undesired C1–C4 alkanes with improved light olefins selectivity. [Display omitted] •n-pentane cracking over MFI zeolites with various Si2O3/Al2O3 ratios (30, 80, 280, 500, and 1500) was investigated.•MFI (280) zeolite at 650 °C showed 51% selectivity for light olefins (C3=/C2= = 0.7) with 23.8% undesirable C2-C4 alkanes.•Phosphorous-modified large crystal MFI catalyst with moderate acid sites inhibited hydrogen transfer reaction.•P/HZ280-LC provide improved light olefins production (selectivity 52.2%, C3=/C2= = 1.3). Catalytic cracking; n-pentane; Phosphorous-modified MFI; Olefins; Ethylene; Propylene.