硅藻土磷酸盐催化剂酸性及对丙烯齐聚的催化作用

Acidity of diatomite phosphate catalyst and its activity in propylene oligomerization

游离磷酸作为硅藻土磷酸盐固体酸催化剂， 用于催化丙烯齐聚和其他反应。采用了离子色谱 （ Ｉ Ｃ）、 Ｈａｍ ｍ ｅｔｔ ｐ Ｈ 指示剂法和 Ｎａ Ｏ Ｈ 溶液化学滴定法， 研究了催化剂中游离磷酸的数量和组成与催化剂活性的关系。结果表明， 游离磷酸由 ５％ —３５％ 正磷酸 （ Ｈ３ Ｐ Ｏ４）、１％ —７％ 焦磷酸 （ Ｈ４ Ｐ２ Ｏ７） 和＜ １％ 的多聚磷酸组成。它直接影响催化剂的酸强度分布。含有 ８％ —１５％ Ｈ３ Ｐ Ｏ４和 ２％ —５％ Ｈ４ Ｐ２ Ｏ７ 的催化剂具有一定数量的中、高强度酸中心， 故其丙烯齐聚催化活性高。

Free phosphoric acid acts as the active component of diatomite phosphate solid acid catalyst in propylene oligomerization and other reactions. The catalyst was characterized by ion chromatography(IC),Hammett pH indicator and chemical titration with NaOH standard solution. The relationship between catalytic activity and the amount and composition of the free phosphoric acid was studied. It was shown that free phosphoric acid consists of 5%～35%H 3PO 4,1%～7%H 4P 2O 7 and <1% polyphosphoric acid. It directly influences the distribution of acid strength. The catalyst, composed of 8%～15% H 3PO 4,2%～5%H 4P 2O 7, had certain amount of strong and medium strength acidic sites, therefore it exhibited high catalytic activity for propylene oligomerization.