تاثیر افزایش مزوحفره‌ها بر فعالیت زئولیت HZSM-5 با نسبت سیلیس به آلومینیوم بالا در فرآیند تبدیل متانول به الفین‌ها

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی شیمی و نفت، دانشگاه صنعتی شریف، تهران، ایران

2 گروه پژوهش‌های کاتالیستی، شرکت پژوهش و فناوری پتروشیمی، شرکت ملی صنایع پتروشیمی، تهران، ایران

چکیده

در این تحقیق تاثیر افزایش مزوحفره‌ها بر عملکرد زئولیت HZSM-5 با نسبت سیلیس به آلومینیوم بالا در فرآیند تبدیل متانول به الفین‌ها مورد بررسی قرار گرفت. بدین‌منظور از روش سیلیس‌زدایی با مواد سدیم هیدروکسید، تتراپروپیل‌آمونیوم هیدروکسید و ستیل‌تری‌متیل‌آمونیوم‌‌برمید جهت ایجاد مزوحفره‌ها استفاده شد. آنالیزهای XRD ،FESEM ،N2 Adsorption/Desorption و NH3-TPD نیز جهت تعیین خصوصیات کاتالیست‌ها بر‌روی نمونه‌ها انجام شد. نتایج آنالیز XRD نشان داد که استفاده از تتراپروپیل‌آمونیوم هیدروکسید در عملیات سیلیس‌زدایی توسط سدیم هیدروکسید در نمونه مزوحفره شده Na-TPA، سبب حفظ ساختار کریستالی زئولیت مرجع Ref-ZSM-5 در این نمونه شده است. تصاویر FESEM این نمونه ایجاد شکاف‌ها و حفرات کوچک بر‌روی سطح کریستال‌ها را نشان داده است. نتایج آنالیز N2 Adsorption/Desorption، افزایش سطح و حجم حفرات مزو را در نمونه زئولیت Na-TPA نسبت به زئولیت مرجع                                  Ref-ZSM-5 تائید کرده است. حفرات مزو تشکیل شده با افزایش دسترسی به سایت‌های فعال داخل ساختار، سبب بهبود فعالیت کاتالیستی این زئولیت شده است. به‌طوری‌که انجام تست راکتوری طولانی مدت بر‌روی این کاتالیست (Na-TPA) پایداری آن را به‌مدت 41 روز با تبدیل متانول بالای 90% نشان داد. متوسط انتخاب‌پذیری پروپیلن، کل الفین‌ها و نسبت پروپیلن به اتیلن نیز در این مدت به‌ترتیب 43، 76 و 6% است. درحالی‌که نتایج زئولیت سلیکون‌زدایی شده با استفاده از ستیل‌تری‌متیل‌آمونیوم‌ برمید و سدیم‌هیدروکسید نشان داد که ساختار زئولیت مرجع Ref-ZSM-5 به‌طور کامل تغییر کرده و غربال مولکولی کاملاً مزوحفره Al-MCM-41 تشکیل شده است. این غربال مولکولی به‌علت ساختار کاملاً مزوحفره و توزیع سایت‌های اسیدی با قدرت کم در فرآیند تبدیل متانول به الفین‌ها هیچ‌گونه فعالیتی نداشت.
 

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

The Effect of Mesoporous Increasing On Activity High Silica HZSM-5 Zeolite in the Methanol Conversion to Olefins

نویسندگان [English]

  • somayeh ahmadpour 1
  • Fereydoon Yaripour 2
  • Farhad Khorasheh 1
1 Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, Iran
2 Catalysis Research Group, Petrochemical Research and Technology Company, National Iranian Petrochemical Company, Tehran, Iran
چکیده [English]

In this paper, the effect of mesoporous increasing on activity high silica ZSM-5zeolite in methanol conversion to olefins investigated. Therefore, for forming the mesoporous, desiliction method with Sodium Hydroxide, tetrapropylammonium hydroxide and cetyltrimethylammonium bromide materials are used. The samples were characterized by XRD, FESEM, N2 Adsorption/Desorption and NH3-TPD techniques. The XRD results indicated that using Tetrapropylammonium hydroxide in desilication process by Sodium Hydroxide (in meso pore Na-TPA sample) caused high crystallinity preservation for Ref-ZSM-5 zeolite. FESEM images for this sample showed cracks and small holes on the surface of crystals. The N2 Adsorption/Desorption results confirmed an increase in the meso pore volume and meso surface area in Na-TPA sample compare to Ref-ZSM-5 zeolite. These new mesoporous, with increasing access to active sites in framework, caused improvement on the catalytic performance. Performing the reactor test on catalyst in same reaction condition showed that this catalyst with methanol conversion higher than 90% in 41 days had acceptable stability. During this time, average of propylene selectivity, total olefins selectivity and propylene to ethylene ratio were 43%, 76% and 6% respectively. While the desilicated sample with Sodium Hydroxide and cetyltrimethylammonium bromide showed complete change from Ref-ZSM-5zeolite to mesoporous Al-MCM-41molecular sieves. This molecular sieves with completely mesoporous structure and, acid sites with low strength did not show activity in the methanol to olefin reaction.
 

کلیدواژه‌ها [English]

  • HZSM-5 zeolite
  • Methanol Conversion to Olefins
  • Desilication
  • Sodium Hydroxide
  • Cetyltrimethylammonium Bromide
[1]. Fathi S., Sohrabi M. and Falamaki C., “Improvement of HZSM-5 performance by alkaline treatments: Comparative catalytic study in the MTG reactions,” Fuel, Vol. 116, pp. 529-537, 2014.##
[2]. Ahmadpour J. and Taghizadeh M., “Selective production of propylene from methanol over high-silica mesoporous ZSM-5 zeolites treated with NaOH and NaOH/tetrapropylammonium hydroxide,” Comptes Rendus Chimie, Vol. 18, No. 8, pp. 834-847, 2015.##
[3]. Rostamizadeh M. and Yaripour F., “Dealumination of high silica H-ZSM-5 as long-lived nanocatalyst for methanol to olefin conversio,” Journal of the Taiwan Institute of Chemical Engineers, Vol. 71, pp. 454-463, 2017.##
[4]. Yaripour F., Shariatinia Z., Sahebdelfar S., and Irandoukht A. , “Effect of boron incorporation on the structure, products selectivities and lifetime of H-ZSM-5 nanocatalyst designed for application in methanol-to-olefins (MTO) reaction,” Microporous and Mesoporous Materials, Vol. 203, pp. 41-53, 2015.##
[5]. Groen J. C., Peffer L. A., Moulijn J. A. and Pérez-Ramırez J., “Mesoporosity development in ZSM-5 zeolite upon optimized desilication conditions in alkaline medium,” Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 241, No. 1-3, pp. 53-58, 2004.##
[6]. Abello S., Bonilla A. and Perez-Ramirez J., “Mesoporous ZSM-5 zeolite catalysts prepared by desilication with organic hydroxides and comparison with NaOH leaching,” Applied Catalysis A: General, Vol. 364, No. 1, pp. 191-198, 2009.##
[7]. Möller K. and Bein T., “Mesoporosity–a new dimension for zeolites,” Chemical Society Reviews, Vol. 42, No. 9, pp. 3689-3707, 2013.##
[8]. Serrano D. and Pizarro P., “Synthesis strategies in the search for hierarchical zeolites,” Chemical Society Reviews, Vol. 42, No. 9, pp. 4004-4035, 2013.##
[9]. Pérez-Ramírez J., Christensen C. H., Egeblad K., Christensen C. H. and Groen J. C., “Hierarchical zeolites: enhanced utilisation of microporous crystals in catalysis by advances in materials design,” Chemical Society Reviews, Vol. 37, No. 11, pp. 2530-2542, 2008.##
[10]. Verboekend D. and Pérez-Ramírez J., “Design of hierarchical zeolite catalysts by desilication,” Catalysis Science & Technology, Vol. 1, No. 6, pp. 879-890, 2011.##
[11]. Mochizuki H., Yokoi T., Imai H., Namba S., Kondo J. N. and Tatsumi T., “Effect of desilication of H-ZSM-5 by alkali treatment on catalytic performance in hexane cracking,” Applied Catalysis A: General, Vol. 449, pp. 188-197, 2012.##
[12]. Bleken F. L., Barbera K., Bonino F., Olsbye U., Lillerud K. P., Bordiga S., Beato P., Janssens T. V. and Svelle S., “Catalyst deactivation by coke formation in microporous and desilicated zeolite H-ZSM-5 during the conversion of methanol to hydrocarbons,” Journal of Catalysis, Vol. 307, pp. 62-73, 2013.##
[13]. Rac V., Rakić V., Miladinović Z., Stošić D. and Auroux A., “Influence of the desilication process on the acidity of HZSM-5 zeolite,” Thermochimica Acta, Vol. 567, pp. 73-78, 2013.##
[14]. Sadowska K., Góra-Marek K., Drozdek M., Kuśtrowski P., Datka J., Triguero J. M. and Rey F., “Desilication of highly siliceous zeolite ZSM-5 with NaOH and NaOH/tetrabutylamine hydroxide,” Microporous and Mesoporous Materials, Vol. 168, pp. 195-205, March 2013.##
[15]. Wan W., Fu T., Qi, R. Shao J. and Li Z., “Coeffect of Na+ and tetrapropylammonium (TPA+) in Alkali Treatment on the Fabrication of Mesoporous ZSM-5 Catalyst for Methanol-to-Hydrocarbons Reactions,” Industrial & Engineering Chemistry Research, Vol. 55, No. 51, pp. 13040-13049, 2016.##
[16]. Yoo W. C., Zhang X., Tsapatsis M. and Stein A., “Synthesis of mesoporous ZSM-5 zeolites through desilication and re-assembly processes,” Microporous and Mesoporous Materials, Vol. 149, No. 1, pp. 147-157, 2012. ##
[17]. Peng P., Wang Y., Rood M. J., Zhang Z., Subhan F., Yan Z., Qin L., Zhang Z., Zhang Z. and Gao X., “Effects of dissolution alkalinity and self-assembly on ZSM-5-based micro-/mesoporous composites: a study of the relationship between porosity, acidity, and catalytic performance,” Cryst. Eng. Comm., Vol. 17, No. 20, pp. 3820-3828, 2015.##
[18]. Peng P., Wang Y., Zhang Z., Qiao K., Liu X., Yan Z., Subhan F. and Komarneni S., “ZSM-5-based mesostructures by combined alkali dissolution and re-assembly: Process controlling and scale-up,” Chemical Engineering Journal, Vol. 302, pp. 323-333, 2016.##
[19]. Schmidt F., Lohe M. R., Büchner B., Giordanino F., Bonino F. and Kaskel S., “Improved catalytic performance of hierarchical ZSM-5 synthesized by desilication with surfactants,” Microporous and Mesoporous Materials, Vol. 165, pp. 148-157, 2013.##
[20]. Yang Y., Sun C., Du J., Yue Y., Hua W., Zhang C., Shen W. and Xu H., “The synthesis of endurable B–Al–ZSM-5 catalysts with tunable acidity for methanol to propylene reaction,” Catalysis Communications, Vol. 24, pp. 44-47, 2012.##
[21]. Xu A., Ma H., Zhang H., Weiyong D. and Fang D., “Effect of boron on ZSM-5 catalyst for methanol to propylene conversion,” Polish Journal of Chemical Technology, Vol. 15, No. 4, pp. 95-101. 2013.##
[22]. Chen H., Wang Y., Meng F., Sun C., Li H., Wang Z., Gao F., Wang X. and Wang S., “Aggregates of superfine ZSM-5 crystals: The effect of NaOH on the catalytic performance of methanol to propylene reaction,” Microporous and Mesoporous Materials, Vol. 244, pp. 301-309, 2017.##
[23]. Selvaraj M., Pandurangan A., Seshadri K. S., Sinha P. K., Krishnasamy V. and Lal K. B., “Comparison of mesoporous Al-MCM-41 molecular sieves in the production of p-cymene for isopropylation of toluene,” Journal of Molecular Catalysis A: Chemical, Vol. 186, No. 1, pp. 173-186, 2002.##
[24]. Selvaraj M., Pandurangan A., Seshadri K. S., Sinha P. K. and Lal K. B., “Synthesis, characterization and catalytic application of MCM-41 mesoporous molecular sieves containing Zn and Al,” Applied Catalysis A: General,Vol. 242, No. 2, pp. 347-364, 2003.##
[25]. Leofanti G., Padovan M., Tozzola G. and Venturelli B., “Surface area and pore texture of catalysts,” Catalysis Today, Vol. 41, No. 1, pp. 207-219, 1998.##
[26]. Rostamizadeh M. and Taeb A., “Highly selective Me-ZSM-5 catalyst for methanol to propylene (MTP),” Journal of Industrial and Engineering Chemistry, Vol. 27, pp. 297-306, 2015.##
[27]. Song C.-M., Jiang J. and Yan Z. f., “Synthesis and characterization of MCM-41-type composite materials prepared from ZSM-5 zeolite,” Journal of Porous Materials, Vol. 15, No. 2, pp. 205-211, 2008.##
[28]. Yinghong Y., Sun Y., Xu Q. and Gao Z., “Catalytic activities and properties of AlHMS mesoporousmolecularsieves,” Applied Catalysis A: General, Vol. 175, No. 1, pp. 131-137, 1998.##
[29]. Wenyong L., Cai Q., Pang W., Yue Y. and Zou B., “New mineralization agents for the synthesis of MCM-41,” Microporous and Mesoporous Materials, Vol. 33, No. 1, pp. 187-196, 1999.##
[30]. Okumura K., Nishigaki K. and Niwa M., “Prominent catalytic activity of Ga-containing MCM-41 in the Friedel–Crafts alkylation,” Microporous and Mesoporous Materials, Vol. 44,  pp. 509-516, 2001.##
[31]. Jana S. K., Takahashi H., Nakamura M., Kaneko M., Nishida R., Shimizu H., Kugita T. and Namba S., “Aluminum incorporation in mesoporous MCM-41 molecular sieves and their catalytic performance in acid-catalyzed reactions,” Applied Catalysis A: General, Vol. 245, No. 1, pp. 33-41, 2003.##
[32]. Kugita T., Jana S. K., Owada T., Hashimoto N., Onaka M. and Namba S., “Mesoporous Al-containing MCM-41 molecular sieves: highly active catalysts for Diels–Alder reaction of cyclopentadiene with α, β-unsaturated aldehydes,” Applied Catalysis A: General, Vol. 245, No. 2, pp. 353-362, 2003.##
[33]. Jana S. K., Kugita T. and Namba S., “Aluminum-grafted MCM-41 molecular sieve: an active catalyst for bisphenol F synthesis process,” Applied Catalysis A: General, Vol. 266, No. 2, pp. 245-250, 2004.##
[34]. Milina M., Mitchell S., Cooke D., Crivelli P. and Pérez‐Ramírez J., “Impact of Pore Connectivity on the Design of LongLived Zeolite Catalysts,” Angewandte Chemie International Edition, Vol. 54, No. 5,  pp. 1591-1594, 2015.##
[35]. Ilias S. and Bhan A., “Mechanism of the catalytic conversion of methanol to hydrocarbons,” ACS Catalysis, Vol. 3, No. 1, pp. 18-31, 2012.##
[36]. Xianyong S., “Catalytic Conversion of Methanol to Olefins over HZSM-5 Catalysts,” Doctoral Dissertation, Technische Universität München, 2013.##
[37]. Ke J.A. and Wang I., “Elucidation of the role of potassium fluoride in the chemical and physical nature of ZSM-5 zeolite,” Materials Chemistry and Physics, Vol. 68, No. 1, pp. 157-165, 2001.##