Physico-Chemical nanomaterials science

Effective etherification and alcohol dehydration using solid acid catalysts prepared from nanoporous activated carbons
Diyuk V. E.1.,  Grishchenko L. M.1, Tsapyuk G. G.1, Mischanchuk A. V.2, Mariychuk R.3, Boldyrieva O. Yu.1, Lisnyak V. V.1,3
1 Faculty of Chemistry, Taras Shevchenko National University of Kyiv, Volodymyrska Street, 64/13, Kyiv 01601, Ukraine.
E-mail: liudmyla.grishchenko@gmail.com; lisnyak@chem.univ.kiev.ua
2 Chuiko Institute of Surface Chemistry of NAS of Ukraine, General Naumov Street, 17, Kyiv 03164, Ukraine.
3 Prešov Universirty in Prešov, Ul. 17 novembra, 1, Prešov 15 080 01, Slovakia.

Solid acid catalysts are widely used in various industrially important processes. An important task is to develop a systematic approach for the chemical modification of the surface of nanoporous activated carbons (NACs) with optimal properties for use in selective adsorption and catalysis processes. The purpose of this work was to prepare and investigate the catalytic performance of solid acid catalysts prepared from nanoporous activated carbons in the reactions of isopropyl alcohol dehydration and methyl tert-amyl ether (MTAE) synthesis. Different approaches have been used to acidify the surface layer, from physical adsorption to covalent grafting of acidic groups. 
Using various methods of investigation such as thermogravimetric analysis, thermoprogrammed desorption mass spectrometry, chemical analysis, electron microscopy, IR spectroscopy, etc., the physical and chemical properties of the prepared solid acid catalysts were comprehensively studied. It is established that the number of acidic groups can reach the value of from 0.15 to 1.3 mmol/g, and the thermal stability of acidic groups depends on the method of modification and pre-treatment of NACs. The minimal temperature at the maximum yield of MTAE for the most active catalysts is in the temperature range of 110–130 °C. 
For the most efficient catalysts of isopropyl alcohol dehydration, the reaction is passed in the moderate low temperatures within 130–160 °C range. While for industrial catalysts, such as aluminum oxide, these temperatures are higher by from 50 to 80 °C at least, and the yield of propylene at these temperatures over Al2O3 catalysts can reach only ~80%. It has been shown the high stability of catalytic action; selected sulfonated NACs can be used in multiple catalysis cycles without substantial losses of their catalytic efficiency.