Quantifying Liquid-Solid Mass Transfer in a Trickle Bed Using $${T}_{2}-{T}_{2}$$ Relaxation Exchange NMR

Abstract

Measurement of the liquid-solid mass transfer coefficient within a trickle bed (i.e. gas-liquid flow within a packed bed) of porous silica pellets is achieved through the use of $${T}_{2}-{T}_{2}$$ T 2 - T 2 relaxation exchange nuclear magnetic resonance (NMR). Compared to many conventional measurement techniques, the NMR method enables measurement of mass transport using pellets of real commercial interest. Mass transfer coefficients measured using the NMR technique over a range of liquid Reynolds number, 0.2 $$\le R{e}_{\mathrm{L}}\le $$ ≤ R e L ≤ 1.4, are compared to a number of literature correlations, with values measured using the NMR method falling within the range predicted by the correlations. The results demonstrate the importance of considering both the flow conditions and the type of pellets used to develop mass transport correlations in trickle beds. This novel NMR application may be utilized in the future to screen catalyst pellets in trickle beds for optimal mass transport properties.