# T1 Relaxation of Methane in Mixtures with Gaseous Water

## TL;DR

This study investigates how methane and water vapor interact in MRI experiments, helping improve the interpretation of reaction data in catalytic processes.

## Contribution

The paper derives the collision cross section of methane with water, enabling better estimation of temperature and concentration in methanation reactions.

## Key findings

- T1 relaxation times of methane-water mixtures were measured under various temperatures and pressures.
- The collision cross section σj,CH4-H2O was derived, aiding in the estimation of methane concentration and temperature.
- The results can improve MRI sequence timing for experiments involving water vapor or methane.

## Abstract

Synthetic, ecofriendly
fuels and chemicals can be produced through
Power-To-X (PtX) processes. To study such catalytic processes operando
and spatially resolved, magnetic resonance imaging (MRI) is a versatile
tool. A main issue in the application of MRI in reactive studies is
a lack of knowledge about how the gathered signals can be interpreted
into reaction data like temperature or species concentration. In this
work, the interaction of methane and gaseous water is studied regarding
their longitudinal relaxation time T1 and
the chemical shift. To this end, defined quantities of methane-water
mixtures were sealed in glass tubes and probed at temperatures between
130 and 360 °C and pressures from 6 to 20 bar. From the obtained T1 relaxation times, the collision cross section
of methane with water σj,CH4-H2O is derived, which can be used to estimate
the temperature and molar concentration of methane during the methanation
reaction. The obtained T1 relaxation times
can additionally be used to improve the timing of MRI sequences involving
water vapor or methane. Further, details about the measurement workflow
and tube preparation are shared.