Elucidating Improvements to MIL‐101(Cr)’s Porosity and Particle Size Distributions based on Innovations and Fine‐Tuning in Synthesis Procedures

Abstract

Abstract Among the existing metal–organic frameworks (MOFs), MIL‐101(Cr) is renowned for its stability in air and water. As a result, MIL‐101(Cr) has numerous potential applications ranging from adsorptive cooling to catalysis. The industrial‐scale production of MIL‐101(Cr) is necessary before realizing these applications. Yet, there remain two main bottlenecks in preparing MIL‐101(Cr) in bulk: the toxicity of hydrofluoric acid (HF) used in conventional MIL‐101(Cr) synthesis and the challenge of ensuring that the as‐prepared MIL‐101(Cr) is highly porous with specific Brunauer–Emmett–Teller surface area (SBET) above 4000 m2 g−1. On the laboratory scale, MIL‐101(Cr) often presents SBET 2300–3500 m2 g−1. The synthesis and purification procedures often influence the yield, particle size, porosity, and other properties of MIL‐101(Cr). This critical review examines trends in MIL‐101(Cr) preparation procedures and the MOF's resulting properties to elucidate areas for improvement toward its real‐world applications. The purification processes for conventional HF‐based MIL‐101(Cr) whereby porosities vary despite the same synthesis approach are first investigated. Next, the reported additives for substituting HF and their influence on the resulting MIL‐101(Cr)’s porosity and particle size are discussed. The selection of additives may be application‐specific: exemplified in the examination of MIL‐101(Cr)’s preparation, its corresponding water sorption capacity, and desiccant‐related applications.

Keywords

• metal–organic frameworks
• particle size
• porosity
• synthesis
• trends
• water sorption