Temperature distribution in a gas-solid fixed bed probed by rapid magnetic resonance imaging

TL;DR

This study demonstrates the use of real-time magnetic resonance imaging combined with the proton resonance frequency shift to obtain 3D temperature maps in a gas-solid fixed bed, revealing temperature gradients with high accuracy.

Contribution

The paper introduces a novel MRI-based thermometry method for in situ temperature measurement in fixed bed reactors, achieving high spatial and temporal resolution.

Findings

Achieved 3D temperature mapping with ±1.5°C accuracy.

Identified axial and radial temperature gradients in the bed.

Validated MRI thermometry against optical temperature probes.

Abstract

Controlling the temperature distribution inside catalytic fixed bed reactors is crucial for yield optimization and process stability. Yet, in situ temperature measurements with spatial and temporal resolution are still challenging. In this work, we perform temperature measurements in a cylindrical fixed bed reactor by combining the capabilities of real-time magnetic resonance imaging (MRI) with the temperature-dependent proton resonance frequency (PRF) shift of water. Three-dimensional (3D) temperature maps are acquired while heating the bed from room temperature to 60~$^{\circ}$C using hot air. The obtained results show a clear temperature gradient along the axial and radial dimensions and agree with optical temperature probe measurements with an average error of $\pm$ 1.5~$^{\circ}$C. We believe that the MR thermometry methodology presented here opens new perspectives for the fundamental study of mass and heat transfer in gas-solid fixed beds and in the future might be extended to the study of reactive gas-solid systems.