Preparation of ultra-high-strength alumina microspheres based on fiber reconstruction via multistage low-carbon alcohol elution

Catalytic reactions play a central role in chemical production, wherein the strength of the catalyst support is key to long-term stable operation. Simple and efficient strength enhancement methods for heterogeneous catalysis have received significant attention. Herein, we developed a variable-temperature gradient elution technology for low-carbon alcohols to improve the crushing strength of microspheres prepared using the sol–gel method in a microfluidic system. Based on gel fiber growth and rearrangement utilizing the hydrogen-bonding effect between low-carbon alcohols and pseudo-boehmite, the pore structure and fiber network can be reconstructed. Low-carbon alcohols with strong hydrogen bonds and low steric hindrance are more conducive to the formation of short fibers when constructing a dense gel network coordinated with higher alcohols. By combining long and short fiber cross-linked networks, the crushing strength of microspheres is significantly improved, and a dense pore structure with a small pore volume forms. After gradient elution, a crushing strength of up to 71.78 N/mm2 can be achieved with a high specific surface area of 254.27 m2/g, which significantly exceeds that of commercial alumina supports with the same pore volume. This efficient method provides an important solution for the long-term, stable operation of catalysts.