一种二价季铵盐改性膨润土的结构表征及催化性能

CHARACTERIZATION AND CATALYTIC ACTIVITY OF BENTONITE MODIFIED BY A DIVALENT QUATERNARY AMMONIUM CATION

以[(CH3)3N(CH2)6N(CH3)3]2Br-]为有机改性剂(MD)、盐酸为酸化剂(H),用先有机化再酸化(MD/H)和先酸化再有机化(H/MD)2种方式对膨润土改性,采用氮吸附技术、XRD、DTG等手段表征其结构,以α-蒎烯异构化为模型反应考察其催化性能。结果表明,MD/H改性膨润土的催化性能随酸活化浓度的增大显著提高,其中以0.5MD/64H改性膨润土的催化性能最好,总的转化率达到90%,莰烯、柠檬烯的选择性较高。改性次序显著影响膨润土的催化活性,MD/H改性膨润土产生的酸活性中心可以加速α-蒎烯异构化,获得高活性的催化剂。H/MD改性的膨润土由于后加MD覆盖了由H+提供的酸活性中心,妨碍α-蒎烯与酸活性中心有效接触,因此其催化活性低。

In this ammonium（MD） by MD （H/MD） dissertation, the bentonite was first exchanged with a kind of divalent quaternary , and then activated with HCl （MD/H）. H-exchanged samples and then modified were also prepared. The samples were characterized by means of N2 adsorption technique, XRD, FTIR, and DTG. The catalytic activity of the organic bentonite in the isomerization of α-pinene was evaluated. The conversions of α-pinene isomerization over MD/H modified bentonites were enhanced with the increase of acid content. The best conversion of α-pinene was 90% catalyzed by 0.5MD/64H modified bentonite, with a high selectivity to camphene and limonene. The sequence of modification was able to significantly influence the catalytic activity of the modified bentonite. The acid active centre of bentonites produced by MD/H modified could accelerate the isomerization of α-pinene, so that the catalyst with high activity was obtained. H/MD modified bentonite possessed a low catalytic activity, because MD covered the acid active centre and could not made the α-pinene contact efficiently with active centre to react.