skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions

Abstract

We present a novel nuclear magnetic resonance (NMR) probe design focused on optimizing the temperature gradient across the sample for high temperature magic angle spinning (MAS) experiments using standard rotors. Computational flow dynamics (CFD) simulations were used to assess and optimize the temperature gradient across the sample under MAS conditions. The chemical shift and linewidth of 207Pb direct polarization in lead nitrate were used to calibrate the sample temperature and temperature gradient, respectively. A temperature gradient of less than 3 °C across the sample was obtained by heating bearing gas flows and adjusting its temperature and flow rate during variable temperature (VT) experiments. A maximum temperature of 350 °C was achieved in this probe using a Varian 5 mm MAS rotor with standard Vespel drive tips and end caps. Time-resolved 13C and 1H MAS NMR experiments were performed at 325 °C and 60 bar to monitor an in-situ mixed phase reverse water gas shift reaction, industrial synthesis of CH3OH from a mixture of CO2 and H2 with a Cu/ZnO/Al2O3 catalyst, demonstrating the first in-situ NMR monitoring of a chemical system at temperatures higher than 250 °C in a pressurized environment. The combination of this high-temperature probe and high-pressure rotors willmore » allow for in-situ NMR studies of a great variety of chemical reactions that are inaccessible to conventional NMR setup.« less

Authors:
 [1]; ORCiD logo [1];  [2]; ORCiD logo [1];  [3];  [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. BATTELLE (PACIFIC NW LAB)
  2. Pacific Northwest National Laboratory
  3. Private Sector
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1572473
Report Number(s):
PNNL-SA-143153
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Solid State Nuclear Magnetic Resonance
Additional Journal Information:
Journal Volume: 102
Country of Publication:
United States
Language:
English
Subject:
NMR, Technology, in situ NMR

Citation Formats

Mehta, Hardeep S., Chen, Ying, Sears, Jesse A., Walter, Eric D., Campos, Matthew, Kothandaraman, Jotheeswari, Heldebrant, David J., Hoyt, David W., Mueller, Karl T., and Washton, Nancy M. A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions. United States: N. p., 2019. Web. doi:10.1016/j.ssnmr.2019.06.003.
Mehta, Hardeep S., Chen, Ying, Sears, Jesse A., Walter, Eric D., Campos, Matthew, Kothandaraman, Jotheeswari, Heldebrant, David J., Hoyt, David W., Mueller, Karl T., & Washton, Nancy M. A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions. United States. doi:10.1016/j.ssnmr.2019.06.003.
Mehta, Hardeep S., Chen, Ying, Sears, Jesse A., Walter, Eric D., Campos, Matthew, Kothandaraman, Jotheeswari, Heldebrant, David J., Hoyt, David W., Mueller, Karl T., and Washton, Nancy M. Tue . "A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions". United States. doi:10.1016/j.ssnmr.2019.06.003.
@article{osti_1572473,
title = {A Novel High-Temperature MAS Probe with Optimized Temperature Gradient across Sample Rotor for In-situ Monitoring of High-Temperature High-Pressure Chemical Reactions},
author = {Mehta, Hardeep S. and Chen, Ying and Sears, Jesse A. and Walter, Eric D. and Campos, Matthew and Kothandaraman, Jotheeswari and Heldebrant, David J. and Hoyt, David W. and Mueller, Karl T. and Washton, Nancy M.},
abstractNote = {We present a novel nuclear magnetic resonance (NMR) probe design focused on optimizing the temperature gradient across the sample for high temperature magic angle spinning (MAS) experiments using standard rotors. Computational flow dynamics (CFD) simulations were used to assess and optimize the temperature gradient across the sample under MAS conditions. The chemical shift and linewidth of 207Pb direct polarization in lead nitrate were used to calibrate the sample temperature and temperature gradient, respectively. A temperature gradient of less than 3 °C across the sample was obtained by heating bearing gas flows and adjusting its temperature and flow rate during variable temperature (VT) experiments. A maximum temperature of 350 °C was achieved in this probe using a Varian 5 mm MAS rotor with standard Vespel drive tips and end caps. Time-resolved 13C and 1H MAS NMR experiments were performed at 325 °C and 60 bar to monitor an in-situ mixed phase reverse water gas shift reaction, industrial synthesis of CH3OH from a mixture of CO2 and H2 with a Cu/ZnO/Al2O3 catalyst, demonstrating the first in-situ NMR monitoring of a chemical system at temperatures higher than 250 °C in a pressurized environment. The combination of this high-temperature probe and high-pressure rotors will allow for in-situ NMR studies of a great variety of chemical reactions that are inaccessible to conventional NMR setup.},
doi = {10.1016/j.ssnmr.2019.06.003},
journal = {Solid State Nuclear Magnetic Resonance},
number = ,
volume = 102,
place = {United States},
year = {2019},
month = {10}
}