## 3 Results  
### Catalyst Characterization  
Figure 3 presents scanning electron microscopy (SEM) images of the SAS (a, b, c) and LiSA (d, e, f) materials at magnifications of 600\(\times\), 1200\(\times\), and 2000\(\times\), respectively. The SEM micrographs of SAS reveal a porous structure composed of irregularly shaped particles that form a network of interconnected voids. At higher magnifications, a rough surface texture and an intricate arrangement of particles with pronounced angular features are observed. The particle size distribution for SAS ranges approximately from 1 to 10 \(\upmu\)m, with an estimated average size of around 5 \(\upmu\)m. In contrast, the SEM micrographs of LiSA exhibit a distinctive morphology characterized by a more uniform distribution of smaller particles. At 1200\(\times\) and 2000\(\times\), LiSA particles display a finer texture, a more homogeneous size distribution, and smoother surfaces compared to SAS. Furthermore, at 2000\(\times\), LiSA particles show a more spherical shape and a more regular pore structure. The particle size distribution for LiSA is narrower, approximately 0.5 to 3 \(\upmu\)m, with an estimated average size of around 1.5 \(\upmu\)m. The differences in morphology and particle size reflect the effects of the lithium impregnation process, contributing to the observed structural uniformity and reduction in particle size. Figure 2: Setup of the fixed-bed reactor for biodiesel production using the 3D-printed aluminosilicate catalyst (LiSA). Figure 4a shows the XRD patterns of the structured aluminosilicate material (SAS) and the lithium-impregnated aluminosilicate (LiSA). The diffractogram of SAS reveals an amorphous structure consistent with the pumice composition, which matches the PDF-5 ICDD database entry 00-041-1481 corresponding to Al\({}_{1.8}\)Si\({}_{2.2}\)Ca\({}_{0.8}\)Na\({}_{0.2}\)O\({}_{8}\). In the case of LiSA, the pattern exhibits a superposition of the amorphous SAS and crystalline lithium silicate (Li\({}_{2}\)SiO\({}_{3}\)), identified by its characteristic peaks at 18.9\({}^{\circ}\), 27.0\({}^{\circ}\), 33.1\({}^{\circ}\), 38.6\({}^{\circ}\), 43.3\({}^{\circ}\), 51.8\({}^{\circ}\), 55.5\({}^{\circ}\), and 59.2\({}^{\circ}\) (space group C m C 21). This indicates the successful integration of lithium into the amorphous pumice matrix. The thermogravimetric analysis (TGA) in Figure 4b demonstrates that both materials, SAS and LiSA, exhibit minimal weight loss, with values below 1.2% over the temperature range from 25 \({}^{\circ}\)C to 1000 \({}^{\circ}\)C. This low weight loss percentage confirms the high thermal stability of both materials. The SAS material shows a gradual weight loss, mainly below 400 \({}^{\circ}\)C, likely due to the desorption of physisorbed water and minor impurities within the aluminosilicate structure. After reaching 400 \({}^{\circ}\)C, the weight loss stabilizes, indicating the absence of significant thermal decomposition at higher temperatures. This stability suggests that the aluminosilicate support is capable of withstanding high temperatures, making it a viable candidate as a catalytic support. The LiSA material demonstrates an even lower weight loss than SAS across the entire temperature range. Initially, up to  
Figure 3: SEM images of SAS (**a**,**b**,**c**) and LiSA (**d**,**e**,**f**) at magnifications of 600\(\times\), 1200\(\times\), and 2000\(\times\), respectively. approximately 200 \({}^{\circ}\)C, LiSA shows a small weight reduction, likely associated with the release of surface-adsorbed water. From 200 \({}^{\circ}\)C to around 500 \({}^{\circ}\)C, LiSA experiences a more gradual weight loss compared to SAS, possibly due to minor structural adjustments or the stabilization of lithium species within the aluminosilicate framework.