Innovation of Hydrothermal Synthesis from the Past and...

INNOVATION OF HYDROTHERMAL SYNTHESIS FRON THE PAST PRESENT Traditional Hydrothermal Synthesis since the end of the 19th century, hydrothermal synthesis of inorganic materials has been carried out. It is defined as the precipitation of these materials from aqueous solutions at temperatures above the boiling point and at pressures greater than ambient pressure. This method is actually environmentally because it does not require any organics or additional processing such as calcinations. That is the reason why it has been widely used for synthesis of a wide range of materials especially metal oxides such as hematite and quartz. Hydrothermal synthesis of quartz was demonstrated several decades ago and now currently used commercially. The traditional hydrothermal synthesis method is carried out in an autoclave type reactor where an aqueous solution is heated slowly to a certain temperature and then aged for several hours or days. In the case of the formation of metal oxides, hydrothermal synthesis method is generally involve two reactions which are hydrolysis of the meal salts followed by dehydration. M(NO ) x + xH O = M(OH) x + xHNO (Hydrolysis) H O x M OH x MOx / 2 2 2 ( ) = + (Dehydration) This method is normally at around 373-473 K. During the heat-up period, the above reactions take place to produce nuclei and eventually crystals. During hydrothermal reactions resulting in materials with the desired microstructure and properties, the homogeneous nucleation and grainShow MoreRelatedWhat Are Zeolites?2215 Words   |  9 Pageswithin the square brackets) composed of 2 aluminate tetrahedra and 4 silicate tetrahedra with a total of 12 oxygen’s. A total of 6 balancing cations are present to regulate the negative charge, and there are 6 water molecules in the cavities. Naturally occurring zeolites are mined from numerous places in the world; however, most are extracted from western America and New Zealand. Zeolites are made synthetically by scientists and engineers in order to study their chemical and physical properties, allowing