Macropores can be introduced into catalysts through several methods:
1. Template-Assisted Synthesis: Templates such as polymers, surfactants, or colloidal particles can be used to create macropores. The template is mixed with the catalyst precursor, and after the formation of the catalyst, the template is removed, leaving behind macropores.
2. Post-Synthesis Modification: Macropores can be introduced into an already synthesized catalyst through techniques such as leaching, where specific components are dissolved out, or through mechanical methods like milling.
3. Natural Formation: Some catalysts, such as certain types of zeolites and aluminas, naturally possess macropores due to their inherent structure or the conditions under which they were formed.
