تأثیر فسفر بر اصلاح زئولیت HZSM-5 سنتز شده با توزیع مختلف آلومینیوم شبکه در واکنش تبدیل کاتالیستی سوخت گاز مایع به اولفین‌های سبک

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه تربیت مدرس

2 دانشگاه تربیت مدرس دانشکده شیمی

چکیده

در این پژوهش، زئولیت­ های HZSM-5 با استفاده از منابع آلومینیوم نیترات و آلومینیوم هیدروکسید و نسبت Si/Al برابر 20 سنتز شد و تاثیر توزیع آلومینیوم روی اصلاح زئولیت HZSM-5 با فسفر در واکنش شکست کاتالیستی سوخت گاز مایع بررسی شد. کاتالیست ­های تهیه­ شده با استفاده از تحلیل­ های طیف­سنجی پراش پرتو ایکس (XRD)، میکروسکوپ الکترونی روبشی گسیل میدانی (FESEM)، جذب و دفع نیتروژن (N2-BET)، طیف­ سنجی فلورسانس اشعه ایکس (XRF)، و دفع برنامه ­ریزی ­شده دمایی آمونیاک (NH3-TPD) مشخصه ­یابی شدند. توزیع آلومینیوم شبکه زئولیت HZSM-5 با استفاده از آنالیز XRF و طیف­ سنجی فرابنفش-مرئی بازتابی (DR UV-Vis)، تعیین شد. بیشترین سهم آلومینیوم­ های منفرد برابر 90/6 درصد برای زئولیت سنتز­شده با آلومینیوم نیترات و بیشترین سهم آلومینیوم­ های نزدیک به ­هم، برابر 47/8 درصد برای زئولیت سنتز­شده با آلومینیوم هیدروکسید بوده است. آزمون­های شکست کاتالیستی نشان دادند که پایداری کاتالیستی و بازده اولفین­های سبک در شکست سوخت گاز مایع توسط زئولیت سنتز­شده با آلومینیوم نیترات نسبت به زئولیت سنتز­شده با آلومینیوم هیدروکسید بالاتر بوده است. پس از گذشت 240 دقیقه از انجام واکنش، بازده اولفین سبک برای زئولیت P/HZSM-5 سنتز­شده با آلومینیوم نیترات از49/8 درصد به 41/5 درصد کاهش یافته است. همچنین، نسبت پروپلین به اتیلن، بازده محصولات سنگین C5+، درصد کک تشکیل ­شده و نرخ غیرفعال­ شدن برای P/HZSM-5 سنتز­شده با آلومینیوم نیترات، به­ترتیب، برابر 0/986، 2%، 6% و 21/31% بوده است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Phosphorus on modification of HZSM-5 zeolite synthesized with different framework aluminum distribution in catalytic transformation of LPG to light olefins

نویسندگان [English]

  • Saeed Abbasizadeh 1
  • Ramin Karimzadeh 2
1 Tarbiat Modares University
2 Tarbiat Modares University
چکیده [English]

Effects of Phosphorus on modification of HZSM-5 zeolite synthesized with different framework aluminum distribution in catalytic transformation of LPG to light olefins
 
Saeed Abbasizadeh1 and Ramin Karimzadeh2*
1- Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran, s.abbasizadeh87@gmail.com
2- Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran, ramin@modares.ac.ir
*Corresponding author
(Received: 2018.06.04, Received in revised form: 2018.07.04, Accepted: 2018.08.01)
 
In this work, HZSM-5 zeolites with aluminum nitrate and aluminum hydroxide and Si/Al ratio 20 were synthesized and the effect of framework aluminum distribution on modification of HZSM-5 with phosphorous were investigated in catalytic cracking of LPG. The prepared catalysts were characterized by X-Ray Diffraction, Field Emission Scanning Electron Microscopy, Nitrogen Adsorption-desorption, X-Ray Fluorescence and NH3-Temperature Programmed Desorption analyses. Aluminum distribution in the framework of HZSM-5 was determined by chemical analysis of X-Ray Fluorescence and reflectance UV-Visible analyses. The highest proportion of single Al atoms was found to be 90.6% for HZAM-5 synthesized with aluminum nitrate and the highest proportion of close Al atoms in the zeolite framework was 47.8% for HZAM-5 synthesized with aluminum hydroxide. The catalytic cracking tests showed that the catalytic stability and the olefin yield in LPG cracking for HZAM-5 synthesized with aluminum nitrate, were greater than those of HZAM-5 synthesized with aluminum hydroxide. After 240 min,the olefin yield just decreased from 49.8% to 41.5% for P/HZSM-5 synthesized with higher single Al atoms. Also, the propylene to ethylene ratio, yield of C5+ heavy products, coke percent and deactivation rate for P/HZSM-5(Nitrate) catalyst were determined to be 0.986, 2%, 6% and 21.31%, respectively.

کلیدواژه‌ها [English]

  • LPG Fuel
  • HZSM-5
  • Single Aluminum
  • Phosphorus
  • Light Olefin
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