Running photocatalysis under pressure changes both the chemistry and the risk profile. More gas dissolves at pressure, which raises the availability of gaseous reactants like CO2, H2 or methane, and can move apparent rates substantially. But pressure also means stored energy, and the design and operation must respect that.
Gases that barely dissolve at ambient pressure dissolve proportionally better as pressure rises, relieving mass-transfer limits in gas-liquid photocatalysis. Equilibria involving gas-phase products or reactants shift with partial pressures, in CO2 hydrogenation photochemistry and similar systems, pressure can change selectivity, not just rate.
Rated vessels with documented pressure class, never improvised window mountings, the window is usually the weakest element, so its pressure rating, clamping method and seal design dominate the mechanical safety case. Pressure monitoring at the vessel, relief protection on every pressurized volume, and a light interface that maintains its rating under pressure, window deformation under pressure changes both safety and optics.
Purge with inert before pressurizing with reactive gas; pressurize gradually while watching the gauge; never exceed the marked rating for temperature and pressure together, ratings are coupled, and the pair matters more than either alone. Depressurize through a safe vent path, and verify zero pressure before opening, every time, without exception.
Relief devices on all pressurized volumes; shields or barriers during pressurized irradiation; rated hardware only, with a pressure test after any disassembly; and written procedures for pressurization, venting and opening. Pressurized photocatalysis is productive exactly as long as these lines hold.
See Perfectlight's pressure-rated photoreactors and catalysis solutions for pressurized configurations.
