Preparation and characterization of Ni/Al₂O₃ catalyst for catalytic reduction of CO₂ to formic acid in the presence of hydrazine hydrate as a hydrogen source

In this study, the catalytic reduction of CO 2 into formic acid was investigated over a Ni/Al 2 O 3 catalyst synthesized by wet-impregnation technique. The CO 2 hydrogenation reaction was performed in a slurry reactor in the temperature range of 100–300 °C and at an autogenerated pressure. The Na 2 CO 3 was used as a CO 2 source, and hydrazine hydrate was used as a hydrogen source. The effect of reaction temperature, catalyst metal loading (5–15 wt%), and catalyst amount were optimized for the higher yield of formic acid. The catalyst was very selective to formic acid, and a very high formic acid selectivity of ∼99 % was achieved in the presence of 10 wt% Ni/Al 2 O 3 catalyst at a much lower reaction temperature of 250 °C. The obtained formic acid yield was ∼53.5 %. The result demonstrated that the Ni/Al 2 O 3 catalyst developed was very promising for the selective hydrogenation of CO 2 molecules to formic acid via the in situ hydrogenation from hydrazine hydrate.