بررسی اثر نوع تمپلیت کاتالیست H-SAPO-34 بر تبدیل متانول به الفین‌های سبک

نوع مقاله: مقاله پژوهشی

نویسندگان

1 پژوهشگاه صنعت نفت، پژوهشکده گاز، واحد تبدیلات گازی

2 پژوهشگاه صنعت نفت، پژوهشکده شیمی- پتروشیمی، واحد مواد افزودنی

چکیده

در این تحقیق اثر نوع تمپلیت بر عملکرد کاتالیستی SAPO-34 در فرآیند تبدیل متانول به الفین‌های سبک در دماهای مختلف بررسی شد. کاتالیست‌ها به روش هیدروترمال و با استفاده از تمپلیت مورفولین، تترا اتیل آمونیوم هیدروکسید و دی پروپیل آمین، با ترکیب مولی ژل 1Al2O3:1P2O5:0.6 SiO2:2 Template :50 H2O سنتز شدند و با استفاده از آنالیزهای XRD ،SEM ،NH3-TPD و TGA-DTA مشخصات آنها ارزیابی گردید. نتایج نشان داد که نوع تمپلیت بر ویژگی کاتالیست نهایی شامل اندازه کریستال، مورفولوژی، کریستالینیتی و خلوص اثر گذاشته و استفاده از مورفولین به عنوان تمپلیت منجر به تولید کریستال‌هایی با اندازه‌ بزرگ‌تر نسبت به سایر تمپلیت‌ها می‌شود. واکنش تبدیل متانول به الفین‌های سبک در مجاورت کاتالیست H-SAPO- 34 با تمپلیت‌های مختلف در دمای C° 450-250، فشار اتمسفر و -1 WHSV= 1 hr بررسی شد. نتایج آزمایشات راکتوری نشان داد که تمام کاتالیست‌ها فعالیت و توزیع محصول واکنش نسبتا مشابهی داشتند. همچنین کاتالیست حاصل از تمپلیت مورفولین کمترین طول عمر را دارد.

کلیدواژه‌ها


عنوان مقاله [English]

The Effect of H-SAPO-34 Template Type on Conversion of Methanol to Light Olefins

نویسندگان [English]

  • Laleh Shirazi 1
  • E. Gangji 1
  • zahra Taheri 2
1 Gas Research Divisaon, RIPI
2 Chemicstry & Petrochemical Divisaon, RIPI
چکیده [English]

Effects of template type on the catalytic performance of SAPO-34 catalyst in conversion of methanol to light olefins (MTO) have been investigated. SAPO-34 molecular sieves were synthesized by hydrothermal method, using morpholine tetraethyl ammonium hydroxide and dipropylamine as the template in the synthesis of gel with molar composition of Al2O3: P2O5: SiO2: template: H2O being 1:1:0.6:2:50, respectively. The produced samples were characterized by XRD, SEM, NH3-TPD and TGA-DTA techniques. These results showed that template type affects crystal size, morphology, crystallinity and purity of samples. It was found that the average SAPO-34 crystal size increased when morpholine was used as the template. Conversion of methanol to light olefins using acidic SAPO-34 as the reaction catalyst was studied in a fixed bed reactor in the temperature range of 250–450 °C, atmospheric pressure and WHSV=1 hr-1. Although all the catalysts showed similar activity and product distribution, the catalyst obtained using morpholine as the template, had the shortest lifetime.

کلیدواژه‌ها [English]

  • SAPO-34
  • Methanol
  • Olefin
  • Morpholine
  • Tetraethylammonium hydroxide
  • Dipropylamine
منابع

[1] Wu X. & Anthony R.G., “Effect of feed composition on methanol conversion to light olefins over SAPO-34”, Appl. Catal. A: Gen., Vol. 218, pp. 241- 250, 2001.

[2] Wu X.C., Abraha M.G. & Anthony R.G., “Methanol conversion on SAPO-34: reaction condition for fixed-bed reactor”, Appl. Catal. A General, Vol. 260, pp. 63-69, 2004.

[3] Keil F.J., Review: “Methanol-To-Hydrocarbons: Process Technology”, Microporous and mesoporous Material, Vol. 29, pp. 49-66, 1999.

[4] Chen J.Q., Bozzano A., Glover B., Fuglerud T. & Kvisle S., “Recent advancements in ethylene and propylene production using the UOP/Hydro MTO process”, Catalysis Today, Vol. 106, pp. 103-107, 2005.

[5] Liu G., Tian P., Zhang Y., Li J., Xu L., Meng Sh. & Liu Zh., “Synthesis of SAPO-34 templated by diethylamine: Crystallization process and Si distribution in the crystals”, Microporous and Mesoporous Materials, Vol. 114, pp. 416-423, 2008.

[6] Liu Z., Sun C., Wang G., Wang Q. & Cai G., “New progress in R&D of lower olefin synthesis”, Fuel Processing Technology, Vol. 62, pp. 161-172, 2000.

[7] Wilson S., Barger P., “The characteristics of SAPO-34 which influence the conversion of methanol to light olefins,Microporous and mesoporous material”, Vol. 29, pp. 117-126, 1999.

[8] Obrzut L.D., Adekkanattu P.M., Thundimadathil J.L., Dubois D.R. & Guin J., “Reducing methane formation in methanol to olefins reaction on metal impregnated SAPO-34 molecular sieve”, React. Kinet. Catal. Lett. Vol. 80, pp. 113-121, 2003.

[9] Prakash A.M., Unnikrishnan S., “Synthesis of SAPO-34: high silicon incorporation in the presence of morpholine as template”, J. Chem. Soc., Faraday Trans., Vol. 90, pp. 2291-2296, 1994.

[10] Dubois D.R., Obrzut D.L., Liu J., Thundimadathil J., Adekkanattu P.M., Guin J.A., Punnoose A. & Seehra M.S., “Conversion of methanol to olefins over cobalt-, manganese- and nickel-incorporated SAPO-34 molecular sieves”, Fuel Process. Technol., Vol. 83, pp. 203-218, 2003.

[11] Hunger M., Seiler M. & Buchholz A., “In situ MAS NMR spectroscopic investigation of the conversion of methanol to olefins on silicoaluminophosphates SAPO-34 and SAPO-18 under continuous flow conditions”, Catalysis Letters., Vol. 74, 61-68, 2001.

[12] Lee Y.J., Baek S.Ch. & Jun K.W., “Methanol conversion on SAPO-34 catalysts prepared by mixed template method”, Applied Catalysis A: General, Vol. 329, pp. 130-136, 2007.

[13] Ye L., Cao F., Ying W., Fang D., Sun Q., “Effect of different TEAOH/DEA combination on SAPO-34’s synthesis and catalytic performance”, J Porous Mater., Vol. 18, pp. 225-232, 2011.

[14] Lok B.M. , Messina C.A., Patton R.L., Gajek R.T., Cannan T.R., Flanigen E.M., “Crystalline silicoaluminophosphates”, US Patent 4440871, 1984.

[15] Liang J., Li H., Zhao S., Guo W., Wang R. & Ying M., “Characteristics and performance of SAPO-34 catalyst for methanol-to-olefin conversion”, Applied Catalysis, Vol. 64, pp. 31-40, 1990.

[16] Dahl I.M., Mostad H., Akporiaye D. & Wendelbo R., “Structural and chemical influences on the MTO reaction: a comparison of chabazite and SAPO-34 as MTO catalysts, Microporous and Mesoporous Materials”, Vol. 29, pp. 185-190, 1999.

[17] Dumitriu E., Azzous A., Hulea V., Lutic D. & Kessler H., “Synthesis, characterization and catalytic activity of SAPO-34 obtained with piperidine as templating agent”, Microporous Materials, Vol. 10, pp. 1-12, 1997.

[18] Parlitz B., Schreier E., Zubowa H.L., Eckelt R., Lieschke E. & Fricke R., “Isomerization of n-Heptane over Pd-Loaded Silico-Alumino-Phosphate Molecular Sieves”, J. Catal., Vol. 155, pp. 1-11, 1995.

[19] Xiao T.C., An L.D. & Wang H.L., “Dependence of the nature and catalytic performance on the synthesis factors of SAPO-5 molecular sieve”, Appl. Catal. A: Gen., Vol. 130, pp. 187-194, 1995.

[20] Chen D., Moljord K., Fuglerud T. & Holmen A., “The effect of crystal size of SAPO-34 on the selectivity and deactivation of the MTO reaction”, Microporous Mesoporous Mater., Vol. 29, pp. 191-203, 1999.

[21] Kang M., “Synthesis and catalytic performance on methanol conversion of NiSAPO-34 crystals (II): catalytic performance under various reaction conditions”, Journal of Molecular Catalysis A: Chemical, Vol. 150, pp. 205-212, 1999.

[22] Liu G., Tian P., Li J., Zhang D., Zhou F. & Liu Zh., “Synthesis, characterization and catalytic properties of SAPO-34 synthesized using diethylamine as a template”, Microporous and Mesoporous Materials, Vol. 111, pp. 143-149, 2008.