Tuning of catalytic CO2 hydrogenation by changing composition of CuO–ZnO–ZrO2 catalysts

• DOI: 10.1016/j.enconman.2016.03.075
• Publication Date: 2016-03-29T18:28:41Z
• Authors: Thongthai Witoon; Nantana Kachaban; Waleeporn Donphai; Pinit Kidkhunthod; Kajornsak Faungna...; Metta Chareonpanich; Jumras Limtrakul
• Keywords: Temperature-programmed reduction

Abstract CO2 hydrogenation was carried out over a series of CuO–ZnO–ZrO2 catalysts prepared via a reverse co-precipitation method. The influence of catalyst compositions on the physicochemical properties of the catalysts as well as their catalytic performance was investigated. The catalysts were characterized by means of N2-sorption, X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), scanning electron microscopy (SEM), H2-temperature programmed reduction (H2-TPR), H2 and CO2 temperature-programmed desorption (H2- and CO2-TPD). The binary CuO–ZrO2 (67:33) catalyst exhibits the highest methanol selectivity at all reaction temperature and its maximum yield of methanol (144.5 gmethanol kgcat−1 h−1) is achieved at 280 °C, owing to the strong basic sites and the largest CuO crystallite size. The addition of Zn to the binary CuO–ZrO2 catalyst causes a higher Cu dispersion and an increased number of active sites for CO2 and H2 adsorption. However, the basic strength of the ternary CuO–ZnO–ZrO2 catalysts is lower than the binary CuO–ZrO2 catalyst which provides the maximum yield of methanol at lower reaction tempertures (240 and 250 °C), depending on the catalyst compositions. The optimum catalyst composition of Cu–Zn–Zr (38.2:28.6:33.2) gives a superior methanol productivity of 219.7 gmethanol kgcat−1 h−1 at 240 °C. The results demonstrate the possibility of controlling catalytic CO2 hydrogenation via tuning the catalyst composition.