负载型硫酸铁对烯烃齐聚催化作用的研究 Ⅳ.不同方法制备的 Fe_2(SO_4)_3/γ-Al_2O_3 的丙烯齐聚反应的考察

STUDIES ON OLEFINS OLIGOMERIZATION CATALYZED BY SUPPORTED FERRIC SULFATE Ⅳ A Study of Propene Oligomerization on Fe 2(SO 4) 3/ γ Al 2O 3 Prepared by Different Procedures

考察了不同方法制备的Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３和Ｆｅ２Ｏ３Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３催化剂对丙烯齐聚反应的催化性能。结果表明，Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３的制备方法对催化剂的催化活性有很大的影响。与直接将Ｆｅ２（ＳＯ４）３担载于γ－Ａｌ２Ｏ３上的制备方法相比，先担载Ｆｅ（ＮＯ３）３于γ－Ａｌ２Ｏ３上，焙烧后再担载（ＮＨ４）２ＳＯ４，再焙烧；或先用氨水将Ｆｅ２（ＳＯ４）３溶液调至ｐＨ＝１．２后形成胶体、再担载于γ－Ａｌ２Ｏ３上制备的Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３催化剂的活性都有明显的提高，这些催化剂表现出更强的酸性。用铝胶替代γ－Ａｌ２Ｏ３浸渍于Ｆｅ２（ＳＯ４）３溶液中，焙烧后制得的Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３也表现出较高的活性，其酸量增大。当Ｆｅ２Ｏ３Ｆｅ２（ＳＯ４）３／γ－Ａｌ２Ｏ３催化剂中Ｆｅ２Ｏ３与Ｆｅ２Ｏ（ＳＯ４）３的Ｆｅ原子比为１５、１２、１１时，催化剂表现出较高的丙烯齐聚催化活性。此类催化剂上出现超强酸中心。强酸中心的增强归于Ｆｅ２Ｏ３与ＳＯ２－４的相互作用。

The catalytic activity of Fe 2(SO 4) 3/ γ Al 2O 3 and Fe 2O 3·Fe 2(SO 4) 3/ γ Al 2O 3 for propene oligomerization and the method of preparation of the former have been studied It has been found that the catalytic activity of the catalysts is dependent on the method of preparation of Fe 2(SO 4) 3/ γ Al 2O 3 Comparing with the Fe 2(SO 4) 3/ γ Al 2O 3 prepared by the conventional method of impregnating γ Al 2O 3 with aqueous Fe 2(SO 4) 3 solution,Fe 2(SO 4) 3/ γ Al 2O 3 prepared by some other methods had stronger acid sites and higher catalytic activity These methods are (1) γ Al 2O 3 loaded with Fe(NO 3) 3,calcined and then loaded with (NH 4)SO 4 followed by calcination;(2) Fe 2(SO 4) 3 solution treated with aqueous ammonia to adjust its pH value to 1 2 before being loaded onto γ Al 2O 3,then followed by calcination at 500℃ after loading ;and (3) mixing of AlO(OH) gel with Fe 2(SO 4) 3 solution and followed by calcination The catalyst Fe 2O 3·Fe 2(SO 4) 3/ γ Al 2O 3 showed higher catalytic activity in propylene oligomerization when the atomic ratio of Fe in Fe 2O 3 and Fe 2(SO 4) 3 was 1∶5,1∶2 and 1∶1 Some superacid sites were observed by TPD The formation of strong acid sites is ascribed to the interaction between Fe 2O 3 and SO 2- 4