سنتز و تعیین مشخصات کاتالیست نانوساختار SAPO-34 تقویت شده با La برای تبدیل متانول به الفین‌های سبک

نوع مقاله: مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی شیمی، دانشگاه صنعتی سهند، شهر جدید سهند، تبریز

2 مرکز تحقیقات راکتور و کاتالیست، دانشگاه صنعتی سهند، شهر جدید سهند، تبریز، ایران

چکیده

در این تحقیق کاتالیست‌های نانوساختار LaAPSO-34 به روش هیدروترمال سنتز شدند. قرارگیری La در ساختار زئولیت می‌تواند سبب کاهش اسیدیته و افزایش طول عمر کاتالیست گردد. کاتالیست‌های حاصله با آنالیزهای XRD، FESEM EDX، BET و FTIR تعیین خصوصیات شدند و در فرآیند تبدیل متانول به الفین‌های سبک مورد ارزیابی قرار گرفتند. الگوهای XRD نشان دادند با افزایش نسبت Si/Al تا مقدار 2/0، بلورینگی افزایش یافته در حالی که با افزایش بیشتر این نسبت، بلورینگی کاهش یافته است. تصاویر FESEM نیز نشان دادند با بیشتر شدن نسبت Si/Al رشد ذرات مکعبی شکل چابازیت کامل‌تر شده است. حضور عناصر سازنده و توزیع یکنواخت آنها در نتایج آنالیز EDX مشاهده گردید. نتایج آنالیز BET نشان داد که با افزایش نسبت Si/Al سطح ویژه کاتالیست‌های نانوساختار LaAPSO-34 افزایش یافته است. حضورگروه‌های عاملی ساختار چابازیت در نسبت‌های مختلف Si/Al، توسط آنالیز FTIR تایید شد. نتایج حاصل از تست‌های عملکردی کاتالیست‌ها حاکی از آن بود که با افزایش نسبت Si/Al از 1/0 تا 3/0 طول عمر کاتالیست افزایش یافت. با این حال با افزایش دمای واکنش میزان تبدیل متانول افزایش یافته است. کاتالیست با نسبت 3/0=Si/Al، بیشترین فعالیت را داشته و میزان تبدیل آن در دمای ºC 500-400، کامل شد. همچنین انتخاب‌پذیری الفین‌های سبک در کاتالیست‌های نانوساختار LaAPSO-34 با نسبت‌های Si/Al برابر 1/0، 2/0 و 3/0 به ترتیب پس از 600، 2000 و min 2600 عبور جریان خوراک، به حدود 60% افت نمود.
 

کلیدواژه‌ها


عنوان مقاله [English]

Synthesis and Characterization of Nanostructured La-Doped SAPO-34 Catalyst for Conversion of Methanol to Light Olefins

نویسندگان [English]

  • Abolfazl Amoozegar 1
  • Mohammad Haghighi 2
1 Chemical Engineering Faculty, Sahand University of Technology, Sahand New Town, Tabriz, Iran
2 Reactor and Catalysis Research Center (RCRC), Sahand University of Technology, Sahand New Town, Tabriz, Iran
چکیده [English]

A series of nanostructured LaAPSO-34 catalysts was synthesized with different Si/Al ratios via hydrothermal method. La incorporation into zeolite framework could result in reduction of catalyst acidity and causing the enhancement of catalyst life time. The as-synthesized catalysts were characterized by XRD, FESEM, EDX, BET and FTIR techniques and tested for methanol to light olefins (MTO) process. XRD results showed that the crystallinity intensified by increasing the Si/Al ratio up to 0.2. Afterwards, it declined and FESEM images revealed that by increasing Si/Al ratio, the growth of the cube-shaped chabazite particles was be more complete. The presence of the constituent elements and uniform distribution of them were observed by EDX analysis. BET results showed that by increasing Si/Al ratio, specific surface area of the nanostructured LaAPSO-34 catalysts increased. FTIR spectrums confirmed framework vibrations of chabazite in different Si/Al ratios. The obtained results of catalytic performance tests illustrated that increasing the Si/Al ratio from 0.1 to 0.3 led to enhancement of catalyst life time. Moreover, it has been found that by increasing the reaction temperature, methanol conversion increased. For the most active catalyst, Si/Al=0.3, the complete conversion was obtained at T=400-500°C. Moreover, by increasing Si/Al ratio, light olefins selectivity of nanostructured LaAPSO-34 catalysts declined to approximately 60% after 600, 2000 and 2600 min time on stream, respectively.
 

کلیدواژه‌ها [English]

  • SAPO-34
  • La
  • Methanol
  • Light Olefins
  • MTO

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