Effect of temperature in the conversion of methanol to olefins (MTO) using an extruded SAPO-34 catalyst
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The methanol-to-olefin (MTO) reaction was investigated in a bench-scale, fixed-bed reactor using an extruded catalyst composed of a commercial SAPO-34 (65 weight percentage, wt-%) embedded in an amorphous SiO2 matrix (35 wt-%). The texture properties, acidity and crystal structure of the pure SAPO-34 and its extruded form (E-SAPO-34) were analyzed and the results indicated that the extrusion step did not affect the properties of the catalyst. Subsequently, E-SAPO-34 was tested in a temperature range between 300 and 500 °C, using an aqueous methanol mixture (80 wt-% water content) fed at a weight hour space velocity (WHSV) of 1.21 h‒1. At 300 °C, a low conversion was observed combined with the catalyst deactivation, which was ascribed to oligomerization and condensation reactions. The coke analysis showed the presence of diamandoid hydrocarbons, which are known to be inactive molecules in the MTO process. At higher temperatures, a quasi-steady state was reached during a 6 h reaction where the optimal temperature was identified at 450 °C, which incidentally led to the lowest coke deposition combined with the highest H/C ratio. Above 450 °C, surges of ethylene and methane were associated to a combination of H-transfer and protolytic cracking reactions. Finally, the present work underscored the convenience of the extrusion technique for testing catalysts at simulated scale-up conditions.
KeywordsMTO SAPO-34 temperature extrusion coke light alkanes
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The authors are grateful to the funders of the Industrial Research Chair on Cellulosic Ethanol and Biocommodities at the University of Sherbrooke for their support. The authors would also like to thank MITACS (Grant number ITO3931) for supporting Ignacio Castellanos- Beltran and Gnouyaro Palla Assima’s salaries during the project.
- 4.Plotkin J S. The changing dynamics of olefin supply/demand. Catalysis Today, 2005, 106(1): 10–14Google Scholar
- 12.Inui T. European Patent, 0418142B1, 1990–09-11Google Scholar
- 27.Sun Q, Ma Y, Wang N, Li X, Xi D, Xu J, Deng F, Yoon K B, Oleynikov P, Terasaki O, Yu J. High performance nanosheet-like silicoaluminophosphate molecular sieves: Synthesis, 3D EDT structural analysis and MTO catalytic studies. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 2014, 2(42): 17828–17839CrossRefGoogle Scholar
- 28.Wang C, Yang M, Tian P, Xu S, Yang Y, Wang D, Yuan Y, Liu Z. Dual template-directed synthesis of SAPO-34 nanosheet assemblies with improved stability in the methanol to olefins reaction. Journal of Materials Chemistry. A, Materials for Energy and Sustainability, 2015, 3(10): 5608–5616CrossRefGoogle Scholar
- 31.Magnoux P, Roger P, Canaff C, Fouche V, Gnep N S, Guisnet M. New technique for the characterization of carbonaceous compounds responsible for zeolite deactivation. In: Proceedings of the 4th International Symposium. Amsterdam: Elsevier, 1987, 317–330Google Scholar
- 34.Mores D, Stavitski E, Kox M H F F, Kornatowski J, Olsbye U, Weckhuysen B M. Space-and time-resolved in-situ spectroscopy on the coke formation in molecular sieves: Methanol-to-olefin conversion over H-ZSM-5 and H-SAPO-34. Chemistry (Weinheim an der Bergstrasse, Germany), 2008, 14(36): 11320–11327Google Scholar
- 41.Sanati M, Hörnell C, Järäs S G. The oligomerization of alkenes by heterogeneous catalysts. Catalysis, 1999, 14(7): 236–287Google Scholar
- 43.Elliott D C. Relation of reaction, time and temperature to chemical composition of pyrolysis oils. In: Soltes E J, Milne T A, eds. Pyrolysis Oils from Biomass, 1988, Chapter 6: 55–65Google Scholar