Cold plasma as environmentally benign approach for activation of zeolite nanocrystals

The present work deals with the removal of organic template, tetraethylammonium (TEA) and activation of Beta zeolite nanocrystals using cold plasma (nonthermal) treatment as efficient and environmentally benign approach. The entire process of nonthermal plasma activation of the nanosized zeolite is monitored in a reactor using real time in situ FTIR. The influence of the environmentally friendly cold plasma treatment in comparison to conventional activation (heating at high temperature in the presence of reducing gases) on the physicochemical properties of Beta zeolite nanocrystals is investigated. It is shown that the cold plasma treatment removes the organic template from the nanosized Beta crystals within several minutes, without carbon deposition and thus eliminating the high temperature treatment and the use of hazardous chemicals. The acidic properties of the nanosized Beta zeolite after calcination and cold plasma treatment using pyridine adsorption and temperature programmed desorption are studied by in situ IR spectroscopy. In addition, the Beta nanocrystals treated by the two methods are characterized by X-ray diffraction. Si-29 NMR spectroscopy and nitrogen sorption. It is shown that the cold plasma treatment is an environmental solution for removal of unwanted products (organic templates) in very short time resulting in energy saving and reduction of hazardous solvents and gases. (C) 2012 Elsevier Inc. All rights reserved.