Mesoporous Ti-MCM-48 photocatalyst, with Si/Ti (wt/wt) ratio of 100, 50 and 25 was effectively applied for CO₂ reduction into methanol under UV–visible light irradiation bearing mid gap energy states and Ti³⁺ sites. The bare Ti-MCM-48 with Si/Ti (wt/wt) ratio of 25 displayed highest photocatalytic methanol yield (85.88 μmol g⁻¹ L⁻¹) with a BET surface area of 1528 m² g⁻¹ and mid gap energy states as determined from the XPS analysis, compared to the other composite ratios. The Ti-MCM-48(25) impregnated with Cu-porphyrin (CuTPP) resulted in methanol yield of 297 μmol·g⁻¹ under 33 mW·cm⁻² simulated light intensity, using 0.1 M Na₂SO₃ in 0.1 M NaOH as supporting electrolytes, which is 3.45 times higher than the bare Ti-MCM-48(25) due to the visible light excitation of the porphyrin macrocycle and charge transition from the lowest occupied molecular orbital (LUMO) of CuTPP to the Ti³⁺ metal centers. Also, methanol yield was studied with CO₂ gas-liquid mass transfer and mass transfer limitations prevailing in the reactor. Mass transfer limitation experiments revealed that metal loading, catalyst concentration, stirring speed and light intensity influence the methanol yield.