S/_2O_8^(2-)/ZrO_2固体超强酸的研究

Studies of Peroxodisulfated Zirconia Solid Superacid

以 S2 O2 - 8 浸渍无定形 Zr(OH) 4 ,制得较 SO2 - 4/Zr O2 酸性更强的固体超强酸 .用正丁烷异构化反应考察了 S2 O2 - 8/Zr O2 的酸性 .结果表明 ,在对 Zr O2 有促进作用的非卤素阴离子中 ,S2 O2 - 8是最好的促进剂 .最佳焙烧条件下 S2 O2 - 8/Zr O2 固体超强酸比 SO2 - 4/Zr O2 的酸性更强 .3 5℃下 ,S2 O2 - 8/Zr O2 上正丁烷异构化反应速率较 SO2 - 4/Zr O2 提高了 1 .2倍 .反应 2 0 h后的正丁烷转化率提高了约 1 .5倍 .用 XRD、TEM和化学分析等手段分析了 S2 O2 - 8/Zr O2 体系的晶化过程、比表面和含硫量 .结果表明 ,与 SO2 - 4/Zr O2 体系形成的固体超强酸的过程类似 ,晶化温度、比表面和含硫量均明显影响 S2 O2 - 8/Zr O2 的酸性强弱 .S2 O2 - 8/Zr O2 的最佳焙烧温度比SO2 - 4/Zr O2 低 5 0℃ ,在 5 0 0～ 80 0℃焙烧的 S2 O2 - 8/Zr O2 可形成纳米级固体超强酸 .

The preparation of peroxodisulfated zirconia(PSZ) solid strong acid catalysts is introduced. It showed more active than sulfated zirconia (SZ) for n-butane isomerization at ambient temperature. Peroxodisulfate is the first type of nonhalide found to be more efficient than sulfate which so far has been found the best one promoted zirconia. The optimum calcination temperature is 600 ℃, which is 50 ℃ lower than that of SZ. The conversion of n-butane over PSZ was 50.4% during 20 h and at 35 ℃, and 36.7% over SZ under the same condition. According to X-Ray differential, TEM, BET and chemical analysis, it can be concluded that the formation of superacids over PSZ is similar to that over SZ. It is worth to point out the particle sizes of PSZ calcined between 500 ℃ and 800 ℃ are in the range of nanometers, and the optimum PSZ has both tetragonal and limited monoclinic zirconia.