1. Practical Applications of Compact, Cryogen-Free High-Resolution 60 MHz Permanent Magnet NMR Systems for
Reaction Monitoring and Online/At-Line Process Control Observing 1H, 19F, and 31P
John C. Edwards*, Tal Cohenⱡ, Paul J. Giammatteo*
*Process NMR Associates, LLC, 87A Sand Pit Rd, Danbury, CT 06810 USA, ⱡ Aspect AI, Shoham, Israel
For the past two decades high resolution 1H NMR at 60 MHz has been utilized to monitor the chemical physical properties of refinery and petrochemical feedstreams and products1. These approaches involve the use of partial least squares regression modelling to correlate NMR spectral variability with ASTM
and other official test methods, allowing the NMR to predict results of physical property tests or GC analysis. The analysis is performed in a stop flow environment where solenoid valves are closed at the beginning of the NMR experiment. This approach allows up to 5 or 6 different sample streams to be sent
to the sample in order to maximize the impact of the instrument. The current work with these permanent magnet NMR systems is to utilize them as chemistry detectors for bench-top reaction monitoring, mixing monitoring, dilution monitoring, or conversion monitoring. In the past use of NMR for these
applications has been limited by the need to bring the “reaction” to the typical "superconducting” NMR lab. A compact high resolution NMR system will be described that can be situated on the bench-top or in the fume hood to be used as a continuous or stop-flow detector and/or an “in-situ” reaction
monitoring system. The system uses a unique 1.4 Tesla permanent magnet that can accommodate sample diameters of 3-10 mm with half-height resolution approaching 1-3 Hz (depending on the sample size) and excellent single pulse sensitivity. Reaction monitoring can be performed using a simple flow cell
analyzing total system volumes of 2 to 5 mL depending on the length and diameter of the transfer tubing. Further, detection limits of analytes in the 200+ ppm range are possible without the use of typical deuterated NMR solvents. Analysis times of 5 to 20 seconds are also possible at flow rates of 1 to 20+
ml/minute. Reaction monitoring directly in standard 5-10 mm NMR tubes using conventional (non-deuterated) reactants, solvents and analytes will also be described. Examples of 1H, 19F and 31P analyses will be described.
1. “Process NMR Spectroscopy: Technology and On-line Applications” John C. Edwards, and Paul J. Giammatteo, in Process Analytical Technology: Spectroscopic Tools and Implementation Strategies for the Chemical and Pharmaceutical Industries, 2nd Ed., Editor Katherine Bakeev, Blackwell-Wiley, 2010
Abstract
Example Application: Steam Cracking Optimization Installed at BASF, Ludwigshaven 2000
Cracker Facility Capacity: 600,000 Tonnes per Year
Control Strategy: Feed Forward Detailed Hydrocarbon Analysis to SPYRO Optimization
NMR Analysis: 3-4 Minute Cycle (Single Stream)
NMR PLS Outputs: Naphtha – Detailed Hydrocarbon PONA Analysis, Density
C4-C10 normal-paraffin, iso-paraffin, aromatics, naphthenes
1st Generation NMR Analyzer
Invensys –Foxboro - 1998-2003
2nd Generation NMR Analyzer
Qualion Ltd. 2003-2011
Typical NMR Analyzer
Environment
Shelter House at Base of
Vaccuum Tower
Sample system providing
2 conditioned streams to NMR
Analyzer
3rd Generation NMR Analyzer
Modcon-Xentaur-Aspect AI
Actual Toluene (Wt%)
PredictedToluene(Wt%)(F9C1)
PLS Model
for Toluene Wt% by PIONA GC
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-.5
1
2.5
4
5.5
0 1.5 3 4.5
Spectral Units ( )
BetaCoefficient(F9C1)
0
10 40 70 100 130
-1.5
1.5
10 40 70 100 130
Cyclopentane
Date
Wt%
GC
NMR
0
2
4
6
8
10
12
14
16
1 147 293 439 585 731 877 1023 1169 1315 1461 1607 1753
iso-C5
iso-C6
iso-C7
iso-C8
iso-C9
4 Month Comparison of Online NMR Prediction and Laboratory GC Analysis
Predictive Vector for Toluene PLS Model
96 Hours of Online Variability Observed by NMR Analyzer for iso-paraffin components
0
0.5
1
1.5
2
2.5
3
3.5
4
1 167 333 499 665 831 997 1163 1329 1495 1661
Benzene
Toluene
Ethyl-Benzene
Xylenes
96 Hours of Online Variability Observed by NMR Analyzer for aromatic components
Examples of the expected resolution obtained on various essential oils at 60 MHz
2.5 2.0 1.5 1.0 ppm
CH3
CH3
CH3
O
O
CH3
CH3
CH3
CH3
OH
OH
O
CH3
A
B
C
D
CH3
O
O
O
CH3
E
E
B
D
A
C
2.5 2.0 1.5 1.0 ppm
60 MHz NMR Reaction
5mm NMR Tube
T-Butyl Alcohol
Reacting with Acetic Anhydride
In the presence of dilute acid.
Aspect 60 MHz NMR System
Sucrose Hydrolysis
Sucrose a-glucose
b-glucose
Esterification of t-BuOH
Integral Graph
And Integration Plot
Esterification of t-BuOH
Superimposed Spectrum Plot
1-Propanol Esterification with Acetic Anhydride
Pure Solution – No Solvent – No Acid Catalyst
8 Hour Reaction Profile
AcAn (7)
AcAn
Acetic Acid
T-BuOH
T-Bu-Ester
Ac-Ester
OH
O
CH3
CH3
O
O
O
CH3
O
O
CH3
CH3
CH3
OH
1,2
1
2 3
3
4
4
5
56
6
7
7
8
8,9
9
Esterification of 1-Propanol by Acetic Anhydride
Integral Plots for Reaction Profile
Ac-Ester
Acetic Acid
1-Pr-Ester
1-PrOH