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Title: Restoring ZSM-5 performance for catalytic fast pyrolysis of biomass: Effect of regeneration temperature

Abstract

Zeolite catalysts used for biomass catalytic fast pyrolysis (CFP) deactivate rapidly, similar to a fluidized catalytic cracking (FCC) catalyst used in refining. To operate effectively when there is rapid deactivation, biomass CFP can take place in a riser FCC-style reactor in which the catalyst has a short contact time (seconds) with reactants before it is regenerated. The regeneration, therefore, has two major needs for effective operation: 1) heat balance, since the heat required for the CFP reactions is brought into the reactor by the hot catalyst and 2) relatively short (minutes) regeneration to restore the catalyst activity to be near its initial state. In order to understand effective conditions to regenerate zeolites used for CFP, a series of experiments were performed to determine the effect of regeneration temperature on the activity of ZSM-5 (SiO 2/Al 2O 3 = 30). After use for pine pyrolysis vapor upgrading, the catalyst was oxidized in 4% O 2 at temperatures between 500-700 °C and reevaluated for the upgrading of pine pyrolysis vapors to assess the extent of regeneration. Additional testing was performed using ethylene aromatization as a surrogate reaction to probe regeneration efficiency. Regeneration experiments were performed for either a fixed length of timemore » (20 min) or until there was no further CO 2 measured in the effluent gas. Results from the ethylene aromatization reactions were shown to serve as an excellent surrogate for CFP reactivity and indicated that the use of model compound studies can effectively be used to understand reaction and regeneration processes from biomass CFP. Both sets of results indicate that a spent ZSM-5 used for biomass CFP could be fully regenerated at 650 degrees C and 700 °C within 20 min, whereas regeneration temperatures of 550 °C and 600 °C required longer regeneration temperatures and in the case of regeneration at 500 °C, there may be coke species that are not removed and the catalyst activity may never be fully restored. Characterization by pyridine diffuse reflectance infrared spectroscopy, thermogravimetric analysis coupled with infrared spectroscopy, and N 2 physisorption showed that higher regeneration temperatures are more effective for restoring Bronsted acid sites and catalyst mesoporosity by rapidly removing aromatic coke deposits. In conclusion, regeneration at 650 °C and 700 °C led to a slightly higher total porosity as compared to the pristine catalyst, which was attributed to the formation of additional mesoporosity from catalyst steaming.« less

Authors:
ORCiD logo [1];  [1];  [1];  [2];  [3]; ORCiD logo [1]; ORCiD logo [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  2. Colorado School of Mines, Golden, CO (United States)
  3. Univ. of Colorado, Boulder, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
OSTI Identifier:
1461851
Report Number(s):
NREL/JA-5100-71999
Journal ID: ISSN 0920-5861
Grant/Contract Number:  
AC36-08GO28308
Resource Type:
Accepted Manuscript
Journal Name:
Catalysis Today
Additional Journal Information:
Journal Volume: 323; Journal ID: ISSN 0920-5861
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; biomass; catalytic fast pyrolysis; zsm-5; regeneration; ethylene aromatization

Citation Formats

Yung, Matthew M., Starace, Anne K., Griffin, Michael B., Wells, Jonathan D., Patalano, Ryan E., Smith, Kylie R., and Schaidle, Joshua A. Restoring ZSM-5 performance for catalytic fast pyrolysis of biomass: Effect of regeneration temperature. United States: N. p., 2018. Web. doi:10.1016/j.cattod.2018.06.025.
Yung, Matthew M., Starace, Anne K., Griffin, Michael B., Wells, Jonathan D., Patalano, Ryan E., Smith, Kylie R., & Schaidle, Joshua A. Restoring ZSM-5 performance for catalytic fast pyrolysis of biomass: Effect of regeneration temperature. United States. doi:10.1016/j.cattod.2018.06.025.
Yung, Matthew M., Starace, Anne K., Griffin, Michael B., Wells, Jonathan D., Patalano, Ryan E., Smith, Kylie R., and Schaidle, Joshua A. Mon . "Restoring ZSM-5 performance for catalytic fast pyrolysis of biomass: Effect of regeneration temperature". United States. doi:10.1016/j.cattod.2018.06.025. https://www.osti.gov/servlets/purl/1461851.
@article{osti_1461851,
title = {Restoring ZSM-5 performance for catalytic fast pyrolysis of biomass: Effect of regeneration temperature},
author = {Yung, Matthew M. and Starace, Anne K. and Griffin, Michael B. and Wells, Jonathan D. and Patalano, Ryan E. and Smith, Kylie R. and Schaidle, Joshua A.},
abstractNote = {Zeolite catalysts used for biomass catalytic fast pyrolysis (CFP) deactivate rapidly, similar to a fluidized catalytic cracking (FCC) catalyst used in refining. To operate effectively when there is rapid deactivation, biomass CFP can take place in a riser FCC-style reactor in which the catalyst has a short contact time (seconds) with reactants before it is regenerated. The regeneration, therefore, has two major needs for effective operation: 1) heat balance, since the heat required for the CFP reactions is brought into the reactor by the hot catalyst and 2) relatively short (minutes) regeneration to restore the catalyst activity to be near its initial state. In order to understand effective conditions to regenerate zeolites used for CFP, a series of experiments were performed to determine the effect of regeneration temperature on the activity of ZSM-5 (SiO2/Al2O3 = 30). After use for pine pyrolysis vapor upgrading, the catalyst was oxidized in 4% O2 at temperatures between 500-700 °C and reevaluated for the upgrading of pine pyrolysis vapors to assess the extent of regeneration. Additional testing was performed using ethylene aromatization as a surrogate reaction to probe regeneration efficiency. Regeneration experiments were performed for either a fixed length of time (20 min) or until there was no further CO2 measured in the effluent gas. Results from the ethylene aromatization reactions were shown to serve as an excellent surrogate for CFP reactivity and indicated that the use of model compound studies can effectively be used to understand reaction and regeneration processes from biomass CFP. Both sets of results indicate that a spent ZSM-5 used for biomass CFP could be fully regenerated at 650 degrees C and 700 °C within 20 min, whereas regeneration temperatures of 550 °C and 600 °C required longer regeneration temperatures and in the case of regeneration at 500 °C, there may be coke species that are not removed and the catalyst activity may never be fully restored. Characterization by pyridine diffuse reflectance infrared spectroscopy, thermogravimetric analysis coupled with infrared spectroscopy, and N2 physisorption showed that higher regeneration temperatures are more effective for restoring Bronsted acid sites and catalyst mesoporosity by rapidly removing aromatic coke deposits. In conclusion, regeneration at 650 °C and 700 °C led to a slightly higher total porosity as compared to the pristine catalyst, which was attributed to the formation of additional mesoporosity from catalyst steaming.},
doi = {10.1016/j.cattod.2018.06.025},
journal = {Catalysis Today},
number = ,
volume = 323,
place = {United States},
year = {2018},
month = {6}
}

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