The improvement of activity and stability of silica (silicon dioxide) as a catalyst support mainly relies on two core technological pathways: surface modification and structural control.  This is achieved through optimizing the dispersion of active components, enhancing thermodynamic stability, and inhibiting sintering/leaching for synergistic reinforcement.

Activity Enhancement Mechanisms
High Specific Surface Area and Pore Structure Control: Silica possesses a specific surface area of 100–300 m²/g and adjustable pore sizes (micropores to mesopores), providing high-density anchoring sites for metal active components (such as Pt, Pd, Ni), significantly improving reactant contact efficiency.
Surface Hydroxyl Functionalization: Surface silanol groups (Si–OH) can introduce acidic/basic sites through chemical bonding, or act as ligands to anchor metal precursors, promoting uniform nucleation of nanoparticles and preventing aggregation.
Surface Coupling Agent Modification: Silanization treatment of silica using silane coupling agents (such as KH550, KH570) can graft organic functional groups (amino, epoxy, vinyl) onto the surface, enhancing compatibility with organic reaction systems and indirectly regulating the electronic state of the metal, thereby improving intrinsic activity.
Stability Enhancement Strategies
Anti-Sintering Mechanism: Forming a dense organosiloxane layer (Si–O–Si) on the surface using silane coupling agents (such as KH590) reduces surface energy and inhibits the migration and aggregation of metal particles at high temperatures.
Anti-Leaching and Chemical Stability: Using dry or wet silanization processes eliminates free hydroxyl groups on the surface, reducing the dissolution of the support in hydrothermal or acidic environments, and improving corrosion resistance.
Core-Shell Structure Construction: Coating the silica surface with alumina, zirconia, or a carbon layer forms a physical barrier, preventing direct contact between the active components and the reaction medium, effectively delaying carbon deposition and deactivation due to poisoning. Recent Research Progress (2020–2025)
Multifunctional Composite Modification: Research focuses on the design of "bifunctional coupling agents," such as silanes containing both amino and thiol groups, to achieve simultaneous metal anchoring and electronic modulation.
In-situ Characterization-Driven Optimization: Utilizing in-situ TEM and XPS techniques, the formation kinetics of Si–O–C bonds on the silica surface after silanization are revealed, providing a theoretical basis for precise control of the modification degree.
Green Modification Process: Development of aqueous-phase silanization and ultrasound-assisted modification techniques reduces the use of organic solvents, improving the environmental friendliness and scalability of the process.
Visualization of Microstructure and Modification Effects
Current Technological Bottlenecks
Difficulty in Controlling Modification Uniformity: Non-uniform surface modification easily occurs in large-scale production, leading to discrete distribution of active components.
High-Temperature Stability Limitations: Under reaction conditions >600 °C, the organosilicon layer is prone to thermal decomposition, and the carrier structure collapses, urgently requiring inorganic-organic hybrid coatings for breakthroughs.
Cost and Process Complexity: Gas-phase silica modification requires high equipment investment, and dry processes consume a large amount of energy, limiting its widespread application in low-to-medium-end catalytic systems.