The data files contain the data reported in the main text of the paper. The Excel file Fig. 1 includes the data of CO conversions, C5+ selectivities and the H2/CO ratios at the reactor outlet collected at different feed H2/CO ratios. The data for the carbon number distributions of the wax products collected from the reactor exit are also included. The Matlab file Fig. 2 includes the data of the 3D intensity MRI image of the reactor. The Matlab file Fig. 3a contains the 2D intensity images of a local catalyst layer measured during the reactor start-up. The Excel file Fig. 3b-e include the data of total signal intensity of the catalyst layer, average diffusion coefficients and carbon numbers of products in catalyst pores and the selectivities of CH4 and C5+ as functions of reaction time. The data of the correlation between pore saturation and product selectivity are also included in file Fig. 3b-e. The Matlab files Fig. 4 and Fig. 5a include the data of 2D images of average diffusion coefficients and carbon numbers at the 3 catalyst layers and 3 different feed ratios. The Excel file Fig. 5b includes the data of the histograms of average carbon numbers. The Matlab file Fig. 6a includes the image data of average carbon number obtained from a local region of a catalyst layer. The Excel file Fig. 6b-c contains the data of the histograms of average carbon numbers collected from a local catalyst pellet and of the carbon number distributions measured from a local position within the catalyst pellet. The Excel file Fig. 7 includes the average carbon numbers of the products confined in catalyst pores and collected from the reactor exit, along with the diffusion coefficients and Henry’s law constants of the H2 and CO dissolved in the products of average carbon number between 20-80. The Matlab file Fig. 8 includes the data of the 2D NMR spectrum correlating chemical shifts and T1 relaxation times.