系统研究了中空纤维Na A分子膜在蒸汽渗透中结合真空抽吸和N2吹扫操作对乙醇深度脱水的过程。研究发现吹扫作用在乙醇深度脱水中占主导作用,与未加吹扫气的对照工况(操作温度100℃、原料液进料流量为30 m L·min^(-1))相比,N_(2)吹...系统研究了中空纤维Na A分子膜在蒸汽渗透中结合真空抽吸和N2吹扫操作对乙醇深度脱水的过程。研究发现吹扫作用在乙醇深度脱水中占主导作用,与未加吹扫气的对照工况(操作温度100℃、原料液进料流量为30 m L·min^(-1))相比,N_(2)吹扫(吹扫气流量为60 m L·min^(-1))可加倍提升脱水速率,快速得到超低含水量乙醇(水的质量分数约0.5%),效率提升约43%;升高温度至120℃时,增大原料液进料流量为50 m L·min^(-1)时乙醇产品中水的质量分数可进一步降至0.068‰,收率达99.86%。展开更多
Due to the low transport resistance,mullite hollow fiber(HF)could be regarded as a promising support for preparation of NaA zeolite membranes.However,insufficient coverage and undesired seed penetration often occur in...Due to the low transport resistance,mullite hollow fiber(HF)could be regarded as a promising support for preparation of NaA zeolite membranes.However,insufficient coverage and undesired seed penetration often occur in the seeding step of the mullite support due to the rough surfaces with ultra-large macropores(2-4 μm).This leads to poor intergrowth of the membrane layer.To solve this issue,cationic polyacrylamide(CPAM)was employed to modify the chemical and electrostatic properties of the mullite HF surface,where the electrostatic attraction between the surface and seed crystals could significantly promote the coating effect.In the seeding,the original seeds(3.2 μm)were mixed with the ball-milled seeds(0.3 μm)to improve the seed coverage,i.e.,the original seed was used to block the macropores on the support surface to prevent the penetration of small seeds,while the decked ball-milled seed was used to provide sufficient active sites to induce the intergrowth of the zeolite crystals.The effects of the concentration of CPAM,mixed mass ratio of seeds,and seed concentration on the preparation of NaA zeolite membranes were systematically examined,where the separation performances were characterized by pervaporation(PV)dehydration of 90%(mass)ethanol/water mixtures at 75℃.The results indicated that under a CPAM concentration of 0.7%(mass),an equivalent mass ratio of mixed seeds in a seed concentration of 1.0%(mass),the prepared mullite HF supported NaA zeolite membrane yielded the best PV performance,where the permeation flux and separation factor corresponded to 5.45 kg·m^(-2)·h^(-1)and 10000,respectively,being sufficient for industrial applications.展开更多
文摘系统研究了中空纤维Na A分子膜在蒸汽渗透中结合真空抽吸和N2吹扫操作对乙醇深度脱水的过程。研究发现吹扫作用在乙醇深度脱水中占主导作用,与未加吹扫气的对照工况(操作温度100℃、原料液进料流量为30 m L·min^(-1))相比,N_(2)吹扫(吹扫气流量为60 m L·min^(-1))可加倍提升脱水速率,快速得到超低含水量乙醇(水的质量分数约0.5%),效率提升约43%;升高温度至120℃时,增大原料液进料流量为50 m L·min^(-1)时乙醇产品中水的质量分数可进一步降至0.068‰,收率达99.86%。
基金supported by the National Natural Science Foundation of China(22178166)Jiangsu Provincial Special Funds of Scientific and Technological Innovation for Carbon Peak and Carbon Neutrality(BE2022033-1,BE2022033-4)Chongqing Municipal Bureau of Science and Technology(cstc2021jcyj-msxmX0748).
文摘Due to the low transport resistance,mullite hollow fiber(HF)could be regarded as a promising support for preparation of NaA zeolite membranes.However,insufficient coverage and undesired seed penetration often occur in the seeding step of the mullite support due to the rough surfaces with ultra-large macropores(2-4 μm).This leads to poor intergrowth of the membrane layer.To solve this issue,cationic polyacrylamide(CPAM)was employed to modify the chemical and electrostatic properties of the mullite HF surface,where the electrostatic attraction between the surface and seed crystals could significantly promote the coating effect.In the seeding,the original seeds(3.2 μm)were mixed with the ball-milled seeds(0.3 μm)to improve the seed coverage,i.e.,the original seed was used to block the macropores on the support surface to prevent the penetration of small seeds,while the decked ball-milled seed was used to provide sufficient active sites to induce the intergrowth of the zeolite crystals.The effects of the concentration of CPAM,mixed mass ratio of seeds,and seed concentration on the preparation of NaA zeolite membranes were systematically examined,where the separation performances were characterized by pervaporation(PV)dehydration of 90%(mass)ethanol/water mixtures at 75℃.The results indicated that under a CPAM concentration of 0.7%(mass),an equivalent mass ratio of mixed seeds in a seed concentration of 1.0%(mass),the prepared mullite HF supported NaA zeolite membrane yielded the best PV performance,where the permeation flux and separation factor corresponded to 5.45 kg·m^(-2)·h^(-1)and 10000,respectively,being sufficient for industrial applications.
