The hydrothermal (solvent) synthesis method involves the pre-dispersion of the precursor of the synthetic zeolite in aqueous (solvent) solution, followed by nucleation, growth, and crystallization at a certain temperature and autogenous pressure to form the zeolite. the first low-silica zeolites were synthesized by Barrer using the low-temperature hydrothermal method in the 1940s, and other types of molecular sieves have been successfully synthesized since then.