Synthesis of hydrothermally stable mesoporous aluminosilicates by using urea as additive

Mesoporous aluminosilicates (MAs) with high hydrothermal stability by assembly Y precursors have been a promising materials for cracking heavy oil. A means to reduce the template consumption and water discharge is of vital importance in synthesis of MAs. Mother liquor recycling (MLR) is an eco-friendly and effective method to synthesize (MAs) with largely reduced template consumption and water discharge. However, inorganic salts accumulation especially for SO42− in the mother liquor with continuous recycling has a negative influence on the micellization of the surfactants. The P123 molecules tend to aggregate into much larger particles and the assembly mother solution becomes cloudy. Less ordered MAs with poor hydrothermal stability would be obtained. In this work, well-ordered MAs with high hydrothermal stability were synthesized via MLR method by introducing urea as additives. Urea acting as salting-in additives behaves opposite to the inorganic salts, which could clear the assembly mother solution by breaking down the P123 aggregates into micelles. After hydrothermal treatment in 100% water vapor at 800 °C for 16 h, the obtained sample maintains 37.7% of specific surface area and 62.1% of total pore volume. In contrast, the sample prepared without adding urea just maintains 15.0% of specific surface area and 20.0% of total pore volume. This strategy provides a high efficiency and low cost route to the synthesis of MAs, which sheds a light on the practical application of MAs.