A micro-reactor for a reforming process has a cold side and a hot side opposite the cold side. Inlets are defined in the cold side, the inlets configured for receiving reagents. An outlet is defined in the cold side, the outlet configured for exiting reforming products. A reforming chamber is in the hot side, the reforming chamber having a catalyst, the reforming chamber configured for reforming the reagents into the reforming products, the reforming chamber including channels extending toward an end surface on the hot side of the reforming chamber, and a return plenum. A reagent path is from the inlets to the reforming chamber, the reagent path configured to feed the plurality of channels with reagents. A reforming product path is from the reforming chamber to the outlet, the reforming product path configured to receive products from the return plenum.

A reactor cell assembly having an annular volume, a top endcap fitting having a reactant gas inlet, a bottom compression endcap fitting having a product gas outlet, a photocatalyst packed bed positioned in the annular volume, a porous base filter to position the photocatalyst packed bed in the annular volume, and a light housing. At least one of an outer portion and an inner portion of the light housing comprises a circumferential array of photon emitters arranged to uniformly emit photons incident on the photocatalyst packed bed to activate continuous photo-induced gas-phase reactions as at least one gaseous reactant introduced via the gas inlet flows through the photocatalyst packed bed and at least one resultant gaseous product exits via the gas outlet.