Comparison of surface acidity/basicity of natural and modified aluminosilicates by conversion of 2-methylbut-3-yn-2-ol
Keywords:
catalytic test reaction, natural alumosilicates, acid and alkaline treatment, basic and acidic sites.Abstract
Surface acidity/basicity of natural and acid/alkali activated aluminosilicates of layered (nontronite,
Nt, glauconite, Gla), framework (clinoptilolite, C95) and a mixed layered type (M45C20) structure were studied
by means of catalytic conversion of 2-methylbut-3-yn-2-ol. Conversion over natural samples decreases in the
order C95 > M45C20 ≈ Nt > Gla. Acidic active sites are dominant on the surface of both natural and acid
treated samples. Acid activation strongly reduced the catalytic activity of zeolite C95 while in case of M45C20
and Nt the conversion slightly increased. The yield of products formed on acid sites decreased by 62% for
C95 and increased by 25; 30 and 100%, respectively for M45C20, Nt and Gla. Catalytic activity of all studied
minerals was significantly suppressed after alkaline activation except for M45C20 for which the increasing
activity of basic sites was observed. The changes in conversion and surface acidity of minerals were
explained by the changes in a ratio of acidic and basic sites induced by surface modification.
