A method of continuously forming AEI-type zeolites in a tubular reactor via a hydrothermal synthesis. A gel composition formed upon using this method includes one or more sources of silica, alumina, organic structure directing agents (OSDA), alkali metal ions; water; and optionally zeolite seeds. This gel composition is defined by the molar ratios of SiO2/AI2O3 15:1 to 100:1; M2O/SiO2 0.15:1 to 0.30:1; ROH/SiO2 0.05:1 to 0.2:1; and H2O/SiO2 5:1 to 20:1; wherein M is the alkali metal ion and R is an organic moiety derived from the OSDA. This gel composition, after reacting at a temperature between 180° C. to about 220° C. for less than 2 hours forms the crystalline AEI-type zeolite having a silica to alumina ratio (SiO2/AI2O3) that is greater than 14:1.