In Situ Flow MAS NMR Spectroscopy

The use of online NMR spectroscopy to monitor catalytic reactions is feasible, and provides high-quality quantitative data under reaction conditions that closely 

Enhanced NMR spectroscopy by dynamic nuclear polarization (DNP) will become a very promising technique for a broad range of applications in heterogeneous catalysis. In [60] it is shown that surface NMR spectra can be greatly enhanced using 

Polarization is transferred from the protons of the solvent to the rare nuclei (here at natural isotopic abundance) at the surface, yielding a 50-fold signal enhancement for surface species covalently incorporated into a silica framework. 

Brookhaven National Laboratory (2012) Proceedings of 4th International Congress on Operando Spectroscopy, Brookhaven National Laboratory, Upton, New York, April 29-May 3, 2012, special issue Catalysis Today, Operando 2012. 

Department of Health and Human Services, Food and Drug Administration (FDA), Center for Drug Evaluation 

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Hunger M (2008) In situ flow MAS NMR spectroscopy State of the art and applications in heterogeneous catalysis. Prog Nucl Magn Reson Spectrosc 53 (3) 105-127... 

Although limited by sensitivity, chemical reaction monitoring via less sensitive nuclei (such as 13C) has also been reported. In 1987 Albert et al. monitored the electrochemical reaction of 2,4,6-tri-t-butylphenol by continuous flow 13C NMR [4]. More recently, Hunger and Horvath studied the conversion of vapor propan-2-ol (13C labeled) on zeolites using 1H and 13C in situ magic angle spinning (MAS) NMR spectroscopy under continuous-flow conditions [15]. 

Fig. 50. In situ MAS NMR spectroscopy of zeolite LaNaY recorded at T=393 K under a continuous flow of C-enriched propan-2-ol with a modified residence time of W/Fp 2 oi=450 g h mol after reaction times of a 30 min, b 2.5 h, and c 7.0 h, with a modified residence time of W/Fp 2 oi=140 gh moh after a reaction time of d 1.0 h, and e after purging the sample with dry carrier gas for 1.0 h [354]...

Coke formation has only been studied for H-SAPO-34 catalyst materials and not for H-ZSM-5 zeolites by means of in situ MAS NMR and UV-vis spectroscopies. Thus, catalyst deactivation is discussed for this particular silicoaluminophosphate molecular sieve on the basis of the results shown in Figure 12.19. By adding the capability of in situ UV-vis spectroscopy to the in situ continuous flow MAS... 

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