钯银合金/陶瓷复合膜体系的氢脱附时间的研究

采用化学镀方法分别制备了Pd、Pd_(95)Ag_5和Pd_(85)Ag_(15)/陶瓷复合膜.研究了不同温度下Pd基复合膜在不锈钢和石英管式分离器两种体系中的氢脱附过程.结果表明,不锈钢分离器体系中的氢脱附缓慢,脱附时间随温度升高而降低.以合金膜Pd_(85)Ag_(15)为例,在673 K两侧F_(N_2)=150 mL/min时,渗透侧的脱附时间为7 h,而进气侧则大于27 h.实验证明不锈钢分离器自身的H_2脱附是该体系脱附的控制步骤.石英分离器体系的氢脱附时间明显缩短,同样的条件下Pd膜的两侧脱附时间分别为75和190 min.实验还证明,传质速率是石英分离器体系氢脱附的控制步骤,而多孔载体能够平抑脱附速率、延长脱附时间.

Study of H_2 release from Pd - Ag/Al_2O_3 composite membrane systems

Three Pd - based membranes, including one pure Pd, one Pd_(95)Ag_5 and another Pd_(85)Ag_(15)/ceramic composite membrane, were prepared by modified electroless plating. H_2 desorption time from these membrane-separator systems after H_2/N_2 shift was measured in both stainless steel and quartz separators at different temperatures. It was proved that the H_2 desorption time is relatively long in the stainless steel separator and decreased as the temperature increased. In the case of Pd_(85)Ag_(15) membrane, the H_2 release time was 7 h and more than 27 h at 673 K with a 150 mL/min sweep gas (N_2) flux on the permeate and feed side, respectively. It was also demonstrated that H_2 desorption from walls of stainless steel separator was the control step of system H_2 re-leasing. However, the H_2 released time of Pd - based membrane decreased markedly i.e. only 75 and 190 min in the quartz separator with the same conditions. In the quartz separator, the flux of sweep gas was the control step of H_2 released from system. Moreover, the mass transfer through porous support decreased the rate of H_2 desorption.