Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydro...Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydrogenation of isobutane in the Pd-Ag/ceramic composite membrane reactor was studied. The effects of various operating parameters,such as reaction temperature, linear velocity of feed gas, linear velocity of purge gas, molar ratio of nitrogen to isobutane in feed gas, and pressure of feed gas on conversion of isobutane were investigated. It was observed that the conversion of isobutane (50.5% at 723 K) in the membrane reactor exceeded the equilibrium conversion (18.8% at 723 K) and that in the fixed-bed reactor (15.5% at 723 K). From experimental results for dehydrogenation of isobutane in the membrane reactor, it was found that when a certain partial pressure of hydrogen was maintained in the reaction-side of the reactor, the formation of accumulative carbon overlayers on the surface of dehydrogenation catalyst and membrane was inhibited to some extent, which reduced the deactivation rate of catalyst and membrane.展开更多
文摘Pd-Ag/ceramic composite membrane, which was prepared by improved electroless plating with osmosis , exhibited higher hydrogen flux,reaching 0.619 mol·s -1 ·m -2 (673 K,Δ p =0.196 MPa). The catalytic dehydrogenation of isobutane in the Pd-Ag/ceramic composite membrane reactor was studied. The effects of various operating parameters,such as reaction temperature, linear velocity of feed gas, linear velocity of purge gas, molar ratio of nitrogen to isobutane in feed gas, and pressure of feed gas on conversion of isobutane were investigated. It was observed that the conversion of isobutane (50.5% at 723 K) in the membrane reactor exceeded the equilibrium conversion (18.8% at 723 K) and that in the fixed-bed reactor (15.5% at 723 K). From experimental results for dehydrogenation of isobutane in the membrane reactor, it was found that when a certain partial pressure of hydrogen was maintained in the reaction-side of the reactor, the formation of accumulative carbon overlayers on the surface of dehydrogenation catalyst and membrane was inhibited to some extent, which reduced the deactivation rate of catalyst and membrane.
文摘采用复合淹没式膜生物反应器(Hybrid Membrane Bioreactor,HMBR)处理城市污水,对反应器污水处理效果、胞外多聚物(Extrace-llular Polymeric Substances,EPS)在反应器中的分布及其与膜污染的关系等问题进行了系统研究。结果表明,反应器出水中SS、COD、BOD5、氨氮的去除率都在93%以上,出水水质稳定。反应器混合液中松散态EPS(Loosely Bond EPS,LB-EPS)和固着态EPS(Tightly Bond EPS,TB-EPS)都随着运行时间而增加,并且与跨膜压差(Trans-Membrane Pres-sure,TMP)的变化存在较强的线性相关关系(R2=0.89);填料生物膜上EPS的质量比随着运行时间的增加也有上升趋势,但与膜污染没有明显的相关关系(R2=0.55);泥饼层中TB-EPS的质量比远高于LB-EPS,EPS与表征膜污染程度的TMP明显相关(R2=0.91),EPS在泥饼层中的积累是造成膜污染的重要因素之一。
