摘要 : Styrene is an important monomer for several synthetic polymer materials in the chemical industry. It is primarily produced by two routes: mainly by an endothermic dehydrogenation of ethylbenzene (EB) and as a co-product of propyle... 展开 Styrene is an important monomer for several synthetic polymer materials in the chemical industry. It is primarily produced by two routes: mainly by an endothermic dehydrogenation of ethylbenzene (EB) and as a co-product of propylene oxide production. Oxidative dehydrogenation (ODH) of EB is a third possibility employing different oxidants, which gained lot of attention recently. The major advantage of ODH process is that, unlike the endothermic dehydrogenation process, it can be operated at a lower temperature, as it is exothermic. More than 90% of styrene is produced worldwide at present based on catalytic dehydrogenation of EB at higher temperatures (> 600 oC) in the presence of large excess of superheated steam. Due to endothermic and volume increasing nature of the reaction, a large amount of superheated steam is required to supply heat, shift the equilibrium to styrene, and avoid the formation of carbonaceous deposits. This process consumes a large amount of energy, since all the latent heat of condensation is not recoverable at the gas-liquid separator after the reaction. Carbon dioxide has received more attention recently as soft oxidant or co-feed gas, instead of steam, since it will be in the gaseous form throughout the dehydrogenation process. For example, the energy requirements for producing styrene employing steam and CO2 were estimated to be 1.5 × 10~9 and 1.9 × 10~8 cal/t-styrene, respectively. Therefore, ODH of EB employing CO2 could be considered as an energy saving process. Further, use of CO2 in the ODH process can accomplish other advantages such as acceleration of reaction rate, alleviation of chemical equilibrium and enhancement in the product selectivity. 收起