The interlayer spacing between hydrotalcite sheets, as determined by PXRD, is smaller -2.3 nm, Table . This implies that N2 adsorption is measuring pores between particles and not the interlayer space. Using simplistic geometrical considerations, if we assume that pores are spaces between aggregated particles and that our particles are disks, as we observe in the TEM images in Figure , then the 3.6 nm diameter pore would translate into a 23.2 nm diameter disk. Details of the calculation are given in SI. This corresponds surprisingly well to the TEM images in Figure , where we note that the shape of the agglomerated particles is disk-like and the diameters of the agglomerates are in the order of 20-30 nm. We conclude that the measured pores are between the agglomerated particles within the larger aggregates.