Recent MRI Studies on Heterogeneous Catalysis

Heterogeneous Catalysis and Parahydrogen‐Induced Polarization

“…3 orders of magnitude lower than in a condensed phase. [106] PHIP can help to overcome these limitations if a suitable catalytic system is addressed.…”

Spatially resolved NMR spectroscopy of heterogeneous gas phase hydrogenation of 1,3-butadiene with parahydrogen

“…3 orders of magnitude lower than that in the condensed phase, which reduces substantially the signal intensity. 14 Therefore, MRI of the gas phase products of heterogeneously catalyzed reactions remains a relatively underdeveloped area despite insightful studies, for instance on mapping the spatial distribution of gases and temperature in ethylene hydrogenation in monolith reactors. 12,[15][16][17] A major improvement in gas imaging can be obtained by exploiting hyperpolarized gases which can provide an up to several orders of magnitude increase in signal intensity and hence in the signal-to-noise ratio (SNR) in NMR experiments.…”

Robust In Situ Magnetic Resonance Imaging of Heterogeneous Catalytic Hydrogenation with and without Hyperpolarization

“…While hyperpolarization techniques such as parahydrogen induced polarization (PHIP) can substantially increase the NMR signal intensity, this general strategy to enable MR imaging of working heterogeneous catalysts to date remains underexplored. [11] Nevertheless, a recent report showed that the distribution of the reactants and products inside a monolith type reactor can be measured even in the gas phase during ethylene hydrogenation reaction using two different catalyst supports, thereby revealing an effect of the support on the mass and heat transport. These catalytic systems permit exploring the complex interplay between chemistry and fluid-dynamics that are typically encountered in practical systems, but mostly absent in simple batch reactors.…”

“…Magnetic resonance imaging (MRI) is a tool applicable to operando studies that provide information for example about the distribution of liquids in the catalyst pellet during hydrogenation of α-methylstyrene [2] or heptene, [3] the coke profiles within a catalyst pellet, [4] the flow of water [5] or propane [6] through a packed bed, the structure of a porous medium and the water flow during the deposition of fines, [7] or the velocities of particles in a fluidized bed. [11] Nevertheless, a recent report showed that the distribution of the reactants and products inside a monolith type reactor can be measured even in the gas phase during ethylene hydrogenation reaction using two different catalyst supports, thereby revealing an effect of the support on the mass and heat transport. 3 orders of magnitude lower relative to the condensed phase, which significantly limits the deployment of MRI for studying gases.…”

“…3 orders of magnitude lower relative to the condensed phase, which significantly limits the deployment of MRI for studying gases. [11] Nevertheless, a recent report showed that the distribution of the reactants and products inside a monolith type reactor can be measured even in the gas phase during ethylene hydrogenation reaction using two different catalyst supports, thereby revealing an effect of the support on the mass and heat transport. [12] Overall, to date, there are only a handful of MRI studies of the gas phase reactions with regular non-hyperpolarized gases.…”