Copper-containing catalysts have shown good activities for ethanol dehydrogenation to acetaldehyde. Acetaldehyde is one of the most important aliphatic chemicals. It can be used as a raw material for production of acetic acid, acetic anhydride, ethyl acetate, butyl aldehyde, crotonaldehyde, pyridine and many other products. Main industrial method of obtaining acetaldehyde is oxidation of valuable ethylene in presence of aqueous solutions of chloride of expensive palladium and copper. This technology is characterized by the formation of a number of toxic chlororganic by-products, as well as dissolved in large quantities of water, acetic acid and croton aldehyde. Recently, against the backdrop of stricter requirements for environmentally friendly technologies and desire to get rid of oil dependence, interest in process of acetaldehyde synthesis by ethanol dehydrogenation increases again. In addition, it is worth noting the importance and value of hydrogen obtained in the process of catalytic dehydrogenation of ethanol along with acetaldehyde. However in order to create a competitive technology for the production of acetaldehyde from ethanol it is necessary to develop an effective catalyst. Activity and selectivity of these catalysts depend on the physical and chemical structure of active components. Dispersion of the metal over the support is an important factor.
In our work the copper catalysts supported on rice husk. Rice husk is the predominant by-product in the milling process of domestic agriculture. It is usually either burned or discarded, resulting not only in resource wasting, but also in environmental pollution. As a consequence, especially in the prevailing field of material science, it makes sense to prepare rice husk (RH), which is composed of extremely amorphous silica. Silica from rice husk was obtained via hydrochloric acid leaching treatment. Silica produced from RH at a temperature of 500 to 650 ? C with a calcination time of 2.5 to 6 h is predominantly amorphous, while crystallinity is achieved when the calcination temperature rises above 700 ? C. Copper catalyst supported on rice husk was prepared by mixing copper nitrate and rice husk. These samples were dried in at 723 K for 3 h. Catalyst activity tests in ethanol conversion were carried out with an automated flow catalytic unit. Results showed that the ethanol is selectivity converted to acetaldehyde when the reaction temperature is between 523-573 K. Ethanol conversion is found to be dependent of calcination temperature of RH and Cu loading.
The results of the work may be of interest to scientists in the field of catalysis and materials science. The fundamental difference between the works is that silicon oxide obtained from rice husk is used as a carrier for copper catalysts.
This research has been is funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. AP08855936)