Effect of promoter TiO₂ on the performance of CuO-ZnO-Al₂O₃ catalyst for CO₂ catalytic hydrogenation to methanol

CuO-ZnO-Al₂O₃ was modified by co-precipitation, using TiO₂ obtained from hydrolyzation of tetra-n-butyl titanate (C₁6H₃6O₄Ti). The catalytic performances were investigated under the conditions of 260℃, 2.6MPa, H₂∶CO₂=3∶1 (volume ratio) and SV of 3600mL/(g·h). The modified samples showed a higher performance than CuO-ZnO-Al₂O₃ and 4% was the optimal dosage. XRD, H₂-TPR, H₂-TPD, NH₃-TPD and CO₂-TPD characterizations were performed. TiO₂ improved CuO dispersion in the catalyst and enhanced the adsorption/activation of CO₂ and H₂ on the surface of catalyst, leading to easier reduction of CuO and lower concentration of strong acid sites on the surface of catalyst simultaneously.