## 1 Introduction  
Porous ceramic supports have attracted significant attention with regard to filtration, absorption, and catalytic applications due to certain intrinsic properties, such as their remarkable hardness and strength, low-thermal-expansion coefficient, stability at high temperatures, and good wear and corrosion resistance. Additionally, they exhibit notable extrinsic properties, including a low-density level, controlled permeability, tailored thermal conductivity, and a high specific surface area [1; 2; 3; 4; 5]. Particularly, a sizeable specific surface area, uniform particle size, narrow pore size distribution and volume, good chemical and thermal stability, and high-mechanical strength are highly desirable to ensure good performance of porous ceramic supports in catalytic applications [2; 4]. The morphology of the support, the processing route, and the raw starting material significantly influence the tailoring of the aforementioned properties of the supports. Supports or ceramic carriers in a powdered form (ranging from nano- to micron-sized particles) have limitations in large-scale applications due to the difficulties in material handling, separation from the process fluids, environmental release, and contamination [2; 6; 7; 8]. Porous materials on the macroscopic scale, specifically millimeter-sized ceramic supports, are considered suitable carrier options that offer ease of handling, high-catalyst-loading percentages within equivalent reactor volumes, high-efficiency levels, good stability, convenient recovery, proper separation, and recyclability after a heterogeneous reaction process [7; 8; 9], while promoting high mass transfer rates [2; 10]. Moreover, it has been suggested that ceramic beads with a spherical shape (sphericity \(\sim\)1, sphericity factor \(\sim\)0) significantly reduce resistance to the transport of reactants and products, as well as catalyst abrasion, compared to non-spherical or irregularly shaped granules [6; 11; 12]. Common liquid-phase-based techniques for processing spherical ceramic carriers, depending on the sol's congealing route, include the granulation methods known as \"oil-molding\" and \"hydrocarbon-ammonia molding\" [13; 14]. These techniques, referred to as \"internal gelation\" and \"external gelation\", respectively, are sol-gel processes used in the fabrication of nuclear fuel kernels [15]. In the oil-molding route, the starting broth, a dispersion of precursors (with controlled acidity) and a gelling agent such as hexamethylenettramine (HMTA) or a mixture of HMTA and urea (organic monomer) [3; 15], is introduced dropwise into hot oil (\(\sim\)90 \({}^{\circ}\)C), resulting in the generation of gel droplets due to surface tension as they enter the oil bath [3; 16]. The sol congeals through neutralization with ammonia ions upon the decomposition of the HMTA and/or urea, while the droplets age in the hot oil [3; 13]. Finally, spherical ceramic carriers are obtained after washing filtration (using organic solvents, ammonia solution, and deionized water), drying, and a heat treatment [3; 13; 15]. The oil molding route has been primarily used to prepare \(\gamma\)-Al\({}_{2}\)O\({}_{3}\) spherical granules [3; 16; 17; 18] and CeO\({}_{2}\)-stabilized-ZrO\({}_{2}\) (CSZ) [15], Al\({}_{2}\)O\({}_{3}\)-CeO\({}_{2}\)[19], Y\({}_{2}\)O\({}_{3}\)-stabilized ZrO\({}_{2}\)[20], and CeO\({}_{2}\)-Nd\({}_{2}\)O\({}_{3}\)[21] fuel kernels and pellets (referred to as internal gelation). Despite the achieved uniformity of the processed spheres, major drawbacks of this method include the toxic nature of the reagents, the requirements of the use and disposal of hot oil together with by-products, and the necessity to maintain the granules under severe processing conditions to complete the decomposition of HMTA and urea [13].