以环戊烷/苯二元物系为例,采用动态模拟软件Aspen Plus Dynamics,对差压热耦合精馏的动态控制性能进行研究与分析。根据其工艺流程特点与分离操作要求建立了一种合理的控制方案。同时,对进料的流量、温度和组成扰动进行分析,考察塔顶、塔釜产品组成和流量等对进料扰动的闭环响应特性,分析该控制方案下差压热耦合精馏工艺对不同干扰因素的抗干扰性能和动态稳定特性。结果显示,该流程动态可控性强,各指标均能在干扰施加后较短时间内达到稳定,对各项干扰的稳定性能良好。
Different semiconductive SiC foam supports were prepared by varying the sintering temperature and atmosphere,and with or without alkaline solution treatment and high temperature oxidation following a macromolecule pyrogenation combined with reaction bonding method.Nano-TiO_2 particles were immobilized onto these SiC foam supports by a composite sol—gel method.The phase,surface morphology,the type of conduction and the photocatalytic activity of the TiO_2—SiC composite photocatalysts were studied.The TiO_2coated on p-type Si-free SiC support showed the highest photocatalytic efficiency in degradation of 4-aminobenzenesulfonic acid(4-ABS) in aqueous solution as compared to that coated on n-type SiC support and p-type SiC supports with residual Si or SiO_2 on the surface.The result showed that the TiO_2 coatings immobilized on p-type semiconductive SiC foam supports exhibited obviously higher photocatalytic activity in comparison to that coated on n-type SiC foam support.The p—n heterojunctions formed between the p-type SiC supports and n-type TiO_2 coatings might be able to account for the better charge separation and transfer as well as the photocatalytic activity of the TiO_2—SiC composite photocatalyst.
