Проведено хлорирование углеродного волокна и получены активные хлорсодержащие прекурсоры, в которых хлор способен замещаться на серосодержащие группы. Показано, что хлорирование позволяет получить образцы с большей концентрацией сульфогрупп в поверхностном слое волокна, по сравнению с образцами, синтезированными прямым методом, а также позволяет увеличить термическую устойчивость полученных катализаторов.
Проведено хлорування вуглецевого волокна і отримані активні хлорвмісні прекурсори, в яких хлор здатний заміщатися на сірковмісні групи. Показано, що хлорування дозволяє отримати зразки з більшою концентрацією сульфогруп в поверхневому шарі волокна, в порівнянні із зразками, синтезованими прямим методом, а також дозволяє збільшити термічну стійкість отриманих каталізаторів.
Chlorination of carbon fibre Busofit was carried out and active chlorine-containing precursors were obtained, chlorine concentration in the surface layer of the obtained samples is 2.5 mmol/g. By TPDMS method it was found that chlorine desorption occurs in the form of HCl (m/z 38 at 36) at temperatures above 200°C. The treatment of chlorinated fibres with aqueous solutions of sodium sulfide or sodium mercaptoacetate provides replacement of surface chlorine by S-containing fu&nctional groups. Further oxidation of obtained samples by hydrogen peroxide leads to formation of strong acidic SO3H-groups in the surface layer. Thermo-desorption properties of the synthesized materials were studied. According to the TPDMS data deso&rption of sulfogroups occurs in the form of SO2 (m/z at 64) in the temperature range 60-300°C. It is shown that the preliminary chlorination allows obtaining samples with higher concentrations of sulfogroups in the fibres surface layer, as compared w&ith the samples synthesized by the direct method. It was found that the concentration of sulfogroups is slightly dependents on the method of sulfonation. It is shown that the fibre samples obtained by the treatment of sodium mercaptoacetate are chara&cterized by a little higher thermal stability as compared to the fiber obtained by treatment with sodium sulfide. Modified materials have sufficiently high thermally stability and can be used in acid-base catalysis. The catalytic activity of CFs samp&les containing strong acidic groups was investigated in model reaction of gas phase dehydration of isopropanol. It is shown that fibres modified with SO3H-groups groups have significantly higher catalytic activity compared to initial ones: conversion& of isopropanol to propylene is increased from 2-3% to 100%. Temperature of 100% conversion was chosen to compare catalytic activity of CFs with acidic SO3H-groups. The highest catalytic activity of the modified CFs is observed for samples that are o&btained from chlorinated precursors treated with sodium sulfide. The lowest activity is observed for samples modified with S-containing compounds without pre-chlorination. In accordance to their catalytic activity all CFs samples are arranged in sequ&ence that fully correlates with the concentration of surface SO3H-groups. Preliminary chlorination increases stability of the obtained catalyst when they are used repeatedly. Sulfur-containing catalysts derived from chlorinated fibers have higher sta&bility in catalysis than their analogues derived from the brominated precursors.
