تأثیر کبالت در کاهش فعالیت آلومینیوم های همسایه در شبکه زئولیت ZSM-5 و نقش آن در افزایش تولید اولفین‌های سبک در شکست کاتالیستی سوخت LPG

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشگاه تربیت مدرس

2 دانشگاه تربیت مدرس دانشکده شیمی

چکیده

در این تحقیق، زئولیت HZSM-5 به روش هیدروترمال سنتز شد و با استفاده از کبالت، اصلاح گردید. زئولیت‌های
HZSM-5 و Co/HZSM-5 به منظور بررسی توزیع محصولات در واکنش شکست کاتالیستی سوخت LPG مورد استفاده قرار گرفته است. کاتالیست‌های تهیه شده با استفاده از آنالیزهای XRD، SEM، BET، XRF و NH3-TPD مشخصه‌یابی شدند. نتایج آنالیز NH3-TPD نشان داد که اسیدیته کاتالیست اصلاح شده Co/HZSM-5 نسبت به HZSM-5کم‌تر است. توزیع آلومینیوم شبکه زئولیت HZSM-5 با استفاده از آنالیز شیمیایی XRF و UV-Visible بازتابی تعیین شد. نتایج نشان داد که سهم آلومینیوم‌های همسایه و آلومینیوم های منفرد در شبکه زئولیت به ترتیب 6/28 و 4/71 درصد بوده است. بازده اولفین‌های سبک در شکست کاتالیستی سوخت LPG توسط زئولیت اصلاح شده با کبالت (1/48 درصد) نسبت به زئولیت HZSM-5 (4/45 درصد) بالاتر بوده است. همچنین، بازده محصولات سنگین C5+، میزان کک تشکیل شده و نرخ غیرفعال شدن برای کاتالیست Co-HZSM-5 نسبت به زئولیت اصلاح نشده پایین‌تر است.

کلیدواژه‌ها


عنوان مقاله [English]

Effect of cobalt in activity reduction of close aluminums in the HZSM-5 framework and its role in enhancing light olefins production in Catalytic cracking of LPG fuel

چکیده [English]

In this investigation, HZSM-5 zeolite with AlCl3 as aluminum source were synthesized by hydrothermal method and modified with cobalt. HZSM-5 and Co/HZSM-5 zeolites were used to investigate the product distribution in LPG fuel cracking. The prepared HZSM-5 and Co/HZSM-5 catalysts were characterized by XRD, FTIR, SEM, BET, XRF, NH3-TPD and Al MAS NMR analyses. The results of NH3-TPD showed that the acidity of Co/HZSM-5 zeolite was lower than HZSM-5. Aluminum distribution in the framework of HZSM-5 was determined by chemical analysis of XRF and reflectance UV-Visible analysis. The results indicated that the proportion of close Al atoms and single Al atoms in the zeolite framework was found to be 28.6% and 71.4%, respectively. The obtained olefin yield for Co/HZSM-5 (48.1%) was higher than HZSM-5 (45.4%) in catalytic cracking of LPG fuel. The yield of C5+ heavy products, the formed coke and deactivation rate for Co/HZSM-5 catalyst were lower than unmodified HZSM-5.

کلیدواژه‌ها [English]

  • LPG fuel
  • HZSM-5
  • Close Aluminum
  • Cobalt
  • Olefin
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