Facile and cost-effective synthesis of acidity-enhanced amorphous silica-alumina for high-performance isomerization

To achieve facile cost-effective synthesis of acidity-enhanced amorphous silica-alumina (ASA), a water-based sol-gel process is developed. Effectively, this method not only enhances acid sites density, but also lowers the cost by using aluminum nitrate nonahydrate instead of expensive organic aluminum precursor. The resulting material has a uniform mesopore distribution (~3.8 ​nm) and a large surface area (455 ​m 2 /g), with very few micropores. And the Brønsted-site density (200 ​°C) is 1.5 times higher than that of commercialized ASA Siral 70, which is ascribed to the abundant four- and five-coordinated aluminum species. The effectiveness of this as-synthesized ASA has been demonstrated for n -hexadecane hydroisomerization, affording a multi-branched isomer yield of 43.1%. In addition, good performance can be expected in other bulky-molecule-involved cracking and alkylation processes.