A novel synthesis process from CO and CO_2 to form alcohol over copperlanthanide complex catalysts

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We inestigated such a novel catalyst system for hydrogenation as the mixture of complex oxide, Cu_6O_8Ln (NO_3), derivatives (Ln : lanthanide). This complex oxide canbe easily decomposed under hydrogen atmosphere form binary system of copper metal and lanthanide. We forcus on the catalytic behavior of the system investigated in the methanol systhesis and the hydrogenation of ethylene.The complex oxide of Cu_6O_8Yb (NO_3) was prepared by thermal decomposition of Cu (NO_3) _2 and Yb (NO_3) _3 mixture under O_2 blowing at 700 K.The structure of the prepared oxide complex was confirmed by XRD.Cu-Yb_2O_3 was then prepared by the decomposition of Cu_6O_8Yb (NO_3) under H_2 atmosphere at prescribed temperature before the reaction.A closed gas circulation system was used to follow the reaction. The reactionmixtures were analyzed by GLC.The catalyst morphology was observed by XRD,XPS and TEM-EDS.CO hydrogenation was carried out over Cu-Yb_2O_3 and the ternary component catalyst, Cu/ZnO/Cr_2O_3. Cu-Yb_2O_3 was prepared from the corresponding complex oxide at 573 K.The main product of CO hydrogenation was methanol and the selectivity for methanol was more than 95 %. The formation of CO_2 was observed other than the hydrogenation. Judging from the time course of the reaction, CO_2 selectively formed at the initial stage and the activity decreased with increasing the passing time. Methanol produced constantly after the period for 2h. We have confirmed that the activity did not decrease over 50 h. At 473K,the Cu-Yb_2O_3 showed maximum activity, which is four times higher than that of the ternary component catalyst, Cu/ZnO/Cr_2O_3.Since Cu-Yb_2O_3 is prepared from the decomposition of Cu_6O_8Yb (NO_3), the activity would be dependent on the preparation temperature. The catalyst pretreated at 523 K showed the maximum activity. The catalyst morphology was studied to elucidate the relationship between the catalytic acftivity and the pretreatment.