CaO-CeO_2固体碱催化剂的制备及催化酯交换反应研究

Preparation of CaO-CeO_2 solid base catalyst and its catalysis in transesterification

采用共沉淀法以草酸钠为沉淀剂合成了一系列不同摩尔比的CaO-CeO_2非均相碱性催化剂,通过XRD、ICP、BET、CO_2-TPD对催化剂进行表征,考察了催化剂中加入Ca/Ce值对催化剂实际Ca/Ce值、比表面积以及碱性的影响,并用于酯交换反应。结果表明:Ca与Ce产生了良好的协同作用,且相较于纯CaO有了更好的形貌结构;在加入Ca/Ce值为1、焙烧温度700℃、催化剂用量3%、反应温度65℃、醇油摩尔比12∶1、反应时间6h时,反应收率达到了97%以上,相较于纯CaO有更好的抗酸性与抗水性;使用后的催化剂用乙醇洗净烘干后放入马弗炉中经过700℃、3h焙烧可以再生,循环使用4次仍然保持较好的催化活性,反应收率在80%以上。

With sodium oxalate as precipitant, a series of heterogeneous basic catalysts of CaO - CeO2 with different molar ratios were synthesized by co - precipatation. The catalysts were characterized by XRD, ICP, BET and CO2 -TPD, and the actual Ca/Ce ratio, specific surface area and basicity of these cata- lysts added with Ca and Ce were examined, also the calalysts were used in transesterification reaction. The results showed that Ca and Ce produced good synergistic effects and the better structures emerged compared with pure CaO. Under the conditions of Ca/Ce ratio 1, calcination temperature 700 ℃, dosage of catalyst 3%, ratio of methanol to palm oil 12： 1, reaction temperature 65℃and reaction time 6 h, the yield exceeded 97%. The acid resistance and water resistance of the catalyst were excellent compared with pure CaO. Meanwhile, the used catalyst could be regenerated by ethanol washing and calcination at 700 ℃ for 3 h and it still had good catalysis activity after reused four cycles with yield above 80%.