*3.1. Characterisation of the LTL Nanocrystals*

The size of the LTL nanoparticles was confirmed to be 50 nm, as measured by DLS (Figure 1a). The DLS provides information on the average size of the crystals as individuals and as aggregates due to random Browning motion in the suspension during the measurements. Therefore, the particle size distribution curve covers the region 25–80 nm but centered at 50 nm. In addition, the size of individual zeolite grains according to the high-resolution transmission electron microscopy study (HRTEM) was determined to be in the range 10–20 nm (Figure 2b). It can be clearly observed that the LTL sample is fully crystalline (Figure 1b) and consists of many aggregates, which are formed from single rectangular crystalline domains with well-defined edges and crystalline fringes (Figure 2b).

**Figure 1.** Dynamic light scattering (DLS) data (**a**) and the X-ray diffraction (XRD) pattern (**b**) of the Linde Type L (LTL) zeolite nanoparticles.

The SEM picture in Figure 2a displays aggregates with the size of 100 to 200 nm with the particles closely connected to each other. These agglomerates are composed of crystalline single nanocrystals of rectangular shape with prominent edges with an average size of 20 nm. The aggregated crystals in the SEM pictures are due to the drying of the LTL colloidal suspension prior to the SEM study.

**Figure 2.** SEM (Scale bar, *M* = 2000 nm) (**a**) and high-resolution transmission electron microscope (HRTEM) (Scale bar, *M* = 10 nm) (**b**) pictures of LTL nanosized zeolite.
