Effect of methanol concentration on lithium aluminosilicate gels

The viscosity of the solution, the diffusion coefficient and the time-to-gel depend on the preparation method used in lithium aluminosilicate gels. The crystallization temperature during heat treatment depends on the preparation method as well. Samples were prepared by adding anhydrous tetraethylorthosilicate (TEOS) toa solution of methanol, water and the nitrates of lithium and aluminum. The amount of methanol was varied to create miscible and immiscible compositions. High methanol compositions took a long time to gel and lost fluidity abruptly. Low methanol compositions took a short time to gel and lost fluidity gradually. Nitrogen sorption techniques were used to determine surface areas in dried and heat treated gels. Low methanol compositions have higher surface areas than high methanol compositions. Thermal analysis was used to identify reaction temperatures. High and low methanol compositions show similar behavior below 400°C but high methanol compositions crystallize beginning around 550°C while low methanol compositions crystallize above 700°C.