Silicon-doped aluminophosphates (SAPOs) are framework materials similar to zeolites. Their pore structure and solid acid sites contribute to their activity and selectivity in the upgrading of petrochemicals. Recent work has suggested that an undesirable side reaction which forms ethylene rather than diethyl ether in ethanol conversion may depend on selectivity of the SAPO framework. The ethylene forms by decomposition of the ether product and is likely to relate to diffusion processes. If the ether product does not freely diffuse out of the pores after formation, it will be in proximity to active sites and liable to decomposition. Measuring diffusion rates of chemicals involved in this reaction is therefore of interest to understand this reaction and inform future SAPO catalyst design.