CO2 hydrogenation to methanol over Cu/ZnO/ZrO2 catalysts prepared by precipitation-reduction method

• Precipitation-reduction method is applied to synthesize the Cu/ZnO/ZrO2 catalysts for CO2 hydrogenation to methanol.
• The NaBH4 content affects the ratio of Cu0/Cu+ on the surface of catalysts.
• A maximum CH3OH selectivity of 66.8% is obtained with NaBH4/Cu = 5 at 503 K.

A series of Cu/ZnO/ZrO2 catalysts were prepared by precipitation-reduction method and tested for the synthesis of methanol by CO2 hydrogenation. The advantages of precipitation-reduction method over conventional co-precipitation method, the effect of NaBH4 content were investigated by XRD, N2 physisorption, SEM, TEM, N2O chemisorption, XPS, TPR, CO2-TPD techniques. The influence of precipitation-reduction process on the average Cu particle size, aggregation state and interaction among different elements were discussed in detail. The content of NaBH4 had an effect on the exposed Cu surface area as well as the ratio of Cu0/Cu+ and thus influenced the catalytic performance. The catalysts prepared by precipitation-reduction method increased the number of basic sites and had a significant advantage in methanol selectivity in contrast with conventional precipitation method. A suitable NaBH4 content was beneficial to the catalytic performance in Cu/ZnO/ZrO2 catalysts and a maximum space time yield of CH3OH was obtained with B/Cu = 5 at 543 K.

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