Research Of Catalyst And Process Of Methanol Synthesis

Three kinds of catalysts, such as CuO/ZnO/Al₂O₃(I^-1 catalyst), CuO/ZnO/Al₂O₃/MgO (II catalysts), CuO/ZnO/Al₂O₃/Ce₂O₃ (III catalysts) and CuO/ZnO/Al₂O₃/MgO/Ce₂O₃(IV catalysts ) were prepared by coprecipitation by step. All their physicochemical properties, such as specific surface, edgewise compressive strength, porosity, total pore volume and bulk density were measured. And then, the catalytic activity of all the catalysts was evaluated in a fixed bed reactor. The results showed that the specific surfaces of all the catalyst are more than 110 m2·g^-1, edgewise compressive strength more than 195 N·cm^-1, porosity more than 65%, total pore volume between 0.3cm3·g^-1 and 0.32 cm3·g^-1, bulk density between 1.25 g·ml^-1 and 1.31g·ml^-1.The results of catalytic properties showed that I^-1 catalyst possessed a high CO conversion but a low selectivity at the low space volecity, and high space volecity is favourate for methanol synthesis. A narrow active temperature was presented in I^-1 catalyst because of its lower heat resistance, and the highest active temperature was 240℃. The activity of II catalysts was improved by adding MgO. The CO conversion more than 90% but the selectivity was only between 15-20% when II catalysts was utilized. The selectivity of III catalysts was improved because of the use of Ce₂O₃. At same time, the range of active temperature also was improved, and the catalysts presented favorable activity when reaction temperature was 250℃. III catalysts possessed optimal catalytic activity when atomic ratio of Cu/Zn/Al/Ce was 6:3:1:0.4. Compared with I-1 catalyst, both activities and selectivities were improved when MgO and Ce₂O₃ were added. IV catalysts also have great heat resistance and active temperature range. When atomic ratio of Cu/Zn/Al/Mg/Ce was 6:3:1:1.0:0.06, the catalysts have favorate properties when the space volecity was 3000h^-1 and temperature was 240℃. The CO conversion was up to 80% and methanol yield was near to 70%.