耐水固体超强酸制备研究

Study on the preparation of water-tolerant solid superacid catalysts

采用低温沉淀陈化法经过滤、干燥、浸渍、再过滤、再干燥和焙烧制备了以ZrO2和TiO2为主要组分的固体超强酸催化剂,并添加镧系过渡金属氧化物进行改性。将所制备的催化剂应用于难以分离水分的乙酸乙酯的合成反应过程,得到该类型催化剂最适宜的制备条件为:n(ZrO2)∶n(TiO2)=1.5∶1,LaC l3的添加量为催化剂中总质量的3%,硫酸浸渍液的浓度为1.0 mol.L-1,焙烧温度和时间为500℃和5 h。低温沉淀陈化法制备的催化剂催化活性高于常温制备的催化剂;改性的催化剂酸强度函数H0<-13.8;所制备的催化剂耐水性明显提高,乙酸乙酯的酯收率达到90%,选择性100%。

Sulfated zirconia-titania oxide solid superacid catalysts modified by lanthanum oxide were prepared by low-temperature （0 ℃ ） precipitation and aging after filtration, drying, re-filtration, re-drying and calcinations. The catalysts prepared were used in synthesis of acetyl acetate where water was difficult to separate. The optimal condition for the synthesis was as follows ： n （ ZrO2 ） ： n （ TiO2 ） = 1.5： 1, doping of LaCl3 equal to 3% of mass of the catalyst, concentration of sulfuric acid impregnating solution = 1.0 mol· L^-1, calcination at 500℃ for 5 h. The results indicated that （ 1 ） Catalysts prepared by precipitation and aging at lower temperature （0 ℃ ） had higher specific surface area, with higher catalytic activity than those prepared at room temperature; （2） Addition of zirconia and lanthanum remarkably increased quantity of acid sites and sulfur in the catalysts, and thus inhibited loss of active ingredientsand enhanced service life of the catalysts and their reusability; （3） The modified catalysts had surface structure with B and L acidic sites, B acid sites being dominating.