La₂O₃를 TiO₂에 담지시켜 제조한 촉매상에서 CO에 의한 SO₂의 환원반응을 조사하였다. La₂O₃의 담지량이 많아지면 CO전화율은 높아지고 COS 생성률은 낮아져 촉매특성이 향상되었다. CO는 실온부터 400 ℃ 범위내에서 거의 흡착되지 않았으며, La₂O₃를 담지시킨 촉매에서는 담지량이 많아지면 SO₂ 흡착량이 증가되었다. 산소 역시 La₂O₃가 담지된 촉매에서 많이 흡착되었다. 산소의 접촉으로 촉매활성은 급격히 감소되었으며 반응기체를 흘려주면 활성이 다시 회복되었다. La₂O₃가 담지된 촉매의 촉매활성 향상과 흡착특성 및 피독실험 결과로부터 이 환원반응의 활성점은 수소처리시 생성된 산소격자 결함이며, La₂O₃에서 산소격자 결함의 생성이 용이하여, La₂O₃담지 촉매의 활성이 증진된 것으로 설명되었다.

The reduction reaction of SO₂ by CO over La₂O₃-impregnated on TiO₂ catalysts was studied. CO conversion was increased and COS selectivity was decreased with increased impregnation of La₂O₃. The adsorption of CO on the catalyst was too small to be measured at temperatures from 25 ℃ to 400 ℃. The adsorption of SO₂ was increased with increasing La₂O₃ impregnation, and that of O₂ also showed the same tendency. When the catalyst was exposed to oxygen during the reaction, the catalytic activity was decreased significantly, but the reduced catalytic activity was restored under the reactant. From these experimental results oxygen lattice vacancy was suggested as the active site of this reaction and the improvement of catalytiz activity due to La₂O₃- impregnation was explained with the high probability of oxygen vacancy formation to La₂O₃.