Influence of Impregnation and Coprecipitation Method in Preparation of Cu/ZnO Catalyst for Methanol Synthesis

Cu/ZnO catalyst was succesfully prepared using a coprecipitation method. The mixing procedure of the Cu(NO 3 ) 2 , Zn(NO 3 ) 2 and Na 2 CO 3 solutions had an important influence on the characteristics of the catalyst. The best catalyst obtained was the one prepared with slow mixing of the salt solutions and a CuO/ZnO molar ratio of 50:50. This raw catalyst had a maximum surface area of about 61.6 m 2 /g. Increasing the CuO/ZnO molar ratio caused an agglomeration of precipitated particles, reducing the surface area. A much better catalyst was obtained using an impregnation method, in which g-Al 2 O 3 was used as support. The impregnated catalyst had a surface area of about 151 m 2 /g. Activity tests were carried out in a fixed-bed reactor containing 1 g of catalyst and a flow of syngas at a rate of 60 mL/min. The reaction temperature was 170°C and the pressure was 20 barg. The best coprecipitated catalyst gave a CO conversion of about 10%, while the impregnated catalyst gave a CO conversion of up to 69%.