Vacuum Pressure Swing Adsorption to Produce Polymer-Grade Propylene

We have evaluated the Vacuum Pressure Swing Adsorption (VPSA) technology to separate propane–propylene streams to produce polymer-grade propylene. Zeolite 4A is used as kinetic adsorbent since propylene diffuses much faster than propane. A single VPSA process is able to produce propylene with purity higher than 99.6%. However, propylene recovery is only 67% and therefore a second stage is used. In this VPSA unit, zeolite 4A with smaller crystal radius is employed to reduce kinetic limitations. The second VPSA (tail unit) produces purified propane and recovers propylene that is recycled to the feed of the first VPSA (front unit). Linking these two VPSA units allows us to produce polymer-grade propylene (PGP) recovering 95.9% of the propylene. Comparing the performance of this process with distillation, there is a significant decrease in the separation volume. However, further efforts are necessary to reduce the power consumption of VPSA which is still slightly higher than for distillation.     

Nanofiltration of Hormone Mimicking Trace Organic Contaminants

Abstract

The removal mechanisms of three hormone mimicking organic compounds by nanofiltration (NF) membranes have been examined. Two NF membranes having different pore sizes were used in laboratory‐scale nanofiltration experiments with feed solutions spiked with a hormone mimicking compound—nonylphenol, tert‐butylphenol, or bisphenol A. Retention of the compounds was determined at various solution chemistries, namely aqueous solution pH, ionic strength, and presence of natural organic matter. The nanofiltration behavior of the selected hormone mimicking compounds appears similar to that of natural hormones as reported in our previous work. While the solution pH can dramatically influence the retention of hormone mimicking compounds by a loose NF membrane, ionic strength does not affect the nanofiltration of such contaminants. However, in the presence of natural organic matter in the feed solution, ionic strength appears to play a significant role in solute‐solute and solute‐membrane interactions, resulting in increased retention due to partitioning of the hormone mimicking compounds onto organic matter at a higher ionic strength.     

Application of Slurry Type Photocatalytic Oxidation‐Submerged Hollow Fiber Microfiltration Hybrid System for the Degradation of Bisphenol A (BPA)

Abstract

A pilot scale, slurry type photocatalytic reactor, followed by submerged hollow fiber microfiltration (MF) membrane hybrid system was evaluated for simultaneous and complete destruction of toxic organic chemical bisphenol A (BPA) and separation of photocatalyst TiO₂; in order to obtain a reusable quality water. With simple modification to the treatment operation, the effect of photocatalytic reaction at modest variations in temperature was examined. Adsorption pretreatment was carried out prior to photocatalysis (UV/TiO₂). BPA adsorption ability on TiO₂ was very less (about 15%) at 25°C. However, adsorption pretreatment followed by photocatalytic oxidation (UV/TiO₂) at an elevated nearly constant temperature (about 70°C) helped in increasing the BPA degradation efficiency. The effect of ozone introduction into the treatment stream was also analyzed. Applying ozone along with UV/TiO₂, brought about a synergistic effect on BPA degradation. Within 3 h, entire 10 ppm of BPA and the by‐product organic compounds were completely removed. TiO₂ particle separation performance using hollow fiber membrane was enhanced by adopting a two‐stage coagulation/sedimentation pretreatment. With initial turbidity of 4000 NTU, the turbidity of the final permeate water was well below 0.1 NTU. Almost complete removal of particles was achieved. Some of the main advantages of this hybrid treatment system include, large‐scale treatment, complete and efficient BPA and its organic intermediates degradation, TiO₂ easily separated after treatment and capable for reuse as it is free from chemical coagulant contaminants, reusable quality water is obtained, and the system has the potential for continuous operation with simple process modifications.     

可生物降解微球甲型肝炎减毒活疫苗口服免疫恒河猴的免疫应答

目的 探索用一种新型的甲型肝炎减毒活疫苗及其免疫途径。方法 用可生物降解的材料聚乳 酸／乙醇酸（ＰＬＡ／ＰＬＧ）包裹甲型肝炎减毒活疫苗,制成微球型疫苗,检测微球的大小及在体外病毒释放的状况,和口 服免疫恒河猴后病毒在体内繁殖及免疫应答状况。结果 微球大小在６～１０μｍ范围,体外病毒抗原释放长达２７ｄ 左右,体外抗原释放高峰在３～７ｄ,口服免疫恒河猴后,约１ｗ左右开始排毒,以后一直呈间断排毒。抗体应答于第 ３ｗ出现,高峰期在５～６ｗ,达１２６１ＭｍＩＵ／ｍｌ,随后逐渐下降,口服加强免疫后,抗体回升,野毒株攻击后,抗体再度回升 达１２４４ｍＩＵ／ｍｌ。结论 微球型甲型肝炎减毒活疫苗口服免疫恒河猴后,能引起一定水平的免疫应答。     

甲型肝炎减毒活疫苗检定方法精确度的探讨

目的 提高甲肝减毒活疫苗检定方法的精确度。方法 比较不同刑量组与剂量组不同的试验数,以 及采用点斜法与Ｒｅｅｄ－Ｍｕｅｎｃｈ法计算ＴＣＩＤ５０。结果 通过比较４种不同的试验设计,发现随着稀释倍数减小或／和各 稀释度试验管数增加,ＴＣＩＤ５０的标准误减小,以减小稀释倍数同时增加各稀释度试验管数,其标准误的缩小最为明显。 点斜法计算的ＩＣＩＤ５０９５％可信区间较Ｒｅｅｄ－Ｍｕｅｎｃｈ法为窄。结论 减小稀释倍数同时增加各稀释度试验管数,并采 用点斜法计算ＴＣＩＤ５０,能使疫苗检定方法的精确度满足规范化甲肝活疫苗滴定的要求。     

甲型肝炎病毒(H2株)快速适应变异株全基因序列分析

目的 探索甲型肝炎病毒（Ｈ２株）细胞适应的分于机制。方法 将甲型肝炎减毒活疫苗毒株（ＨＡＶ Ｈ２Ｋ７）在人胚肺二倍体细胞ＫＭＢ１７上快速连续传代增强适应（１４ｄ）,检测连续传代后抗原滴度和感染性滴度,测定 第１８代（ＨＡＶ Ｈ２Ｋ７Ｐ１８）全基因组序列。结果 适应至第１８代抗原滴度达１：５１２,感染性滴度为７．５ＬｏｇＣＣＩＤ５０／ｍｌ。 整个基因组出现了１０个核苷酸突变,变异卒为０．１３％,变异较大区域位于５’末端非编码区（５’ＵＴＰ）,有３个核苷酸 变异。编码区７个交变,２个是无义突变,５个有义突变导致５个氨基酸变化,分别位于 ＶＰ２ Ａ－Ｓ;２Ｃ,Ｑ－Ｐ;３Ａ,Ｒ－ Ｃ;３Ｃ,Ｔ－Ａ和３Ｄ,Ｖ－Ｇ。结论 ＨＡＶ Ｈ２Ｋ７４因组５’ＵＴＲ、２Ｃ区、３Ａ区、３Ｃ区和３Ｄ区变异协同作用促进在 ＫＭＢ１７ 细胞上快速增强适应。     

A301氨合成催化剂最佳操作条件与催化活性的关系

用高压氨合成催化剂性能评价装置 ,研究了反应温度、压力、空速、惰性气体含量、氢氮比和催化剂粒度对 A30 1催化剂活性的影响。A30 1催化剂在 15 MPa下的最适反应温度在 430～ 480℃ ,在 7MPa下在 376～ 45 0℃ ,比 A110 - 2低 15～ 35℃。A30 1催化剂的最佳 H2 ,N2 摩尔比 nm在 45 0℃时为 2 .5 5～ 3.0 ,在 40 0℃时为 2 .2 3～ 2 .5 5 ,在 35 0℃时为 1.76～ 2 .2 2 ,并可用 nm=1 .5 0 +1 .49( c NH3/ c*NH3)来表示。惰性气体含量会使催化剂活性大幅度降低 ,每当惰性气体含量增加 1 % ,出口氨浓度 (氨净值 )平均降低 0 .2 %～ 0 .3 5 %。颗粒大小对活性或反应速率有严重的影响 ,其内表面利用率受反应温度和催化效率两个因素的影响 ,对于高活性的 A3 0 1催化剂 ,催化效率的因素起主要作用。根据实验结果和合成氨反应的基本理论 ,讨论并提出了A3 0 1催化剂在合成氨生产中的最佳操作工艺条件     

S-200径向氨合成塔使用A301催化剂模拟计算

根据我国引进的TopsφeS-200两段段间间接焕热径向氨合成塔的原有结构参数与工况条件,采用拟均相一维数学模型,模拟计算了使用A301催化剂的应用效果。S-200型径向氨合成塔在现有工况条件下使用A301型催化剂,合成塔出口氨浓度可达19.51%-21.33%,氨净值比使用A110提高1.5-2.5个百分点;最高日产合成氨可达1300t,在各种进塔气流量条件下,均可比使用A110增产10%-14%;在同样的合成氨产量条件下,循环气压缩功耗可比A110降低15%;废热锅炉的蒸汽产量可比使用A110提高15%-20%。结果表明,引进的大型合成氨厂第2次改造和催化剂更换采用A301型催化剂可以达到节能降耗和增产的目的。     

A110-1型氨合成催化剂升温还原总结

叙述了A110－1型氨合成催化剂的装填、升温还原的原则及过程,并与其它类型催化剂升湿还情况进行比较,总结了使用效果。     

Effects of bimetallic catalyst composition and growth parameters on the growth density and diameter of carbon nanotubes

Multi-wall carbon nanotubes (MWNTs) were synthesized by catalytic decomposition of acetylene over Fe, Ni and Fe-Ni bimetallic catalysts supported on alumina under various controlled conditions. The growth density and diameter of CNTs were markedly dependent on the activation time of catalysts in H₂ atmosphere, reaction time, reaction temperature, flow rate of acetylene, and catalyst composition. Bimetallic catalysts were apt to produce narrower diameter of CNTs than single metal catalysts. For the growth of CNTs at 600 ‡C under 10/100 seem flow of C₂H₂/H₂ mixture, the narrowest diameter about 20 nm was observed at the reaction time of 1 h for 20Fe : 20Ni : 60Al₂O₃ catalyst, but at that of 1.5 h for 10Fe : 30Ni : 60Al₂O₃ catalyst. It was considered that the diameter and density of CNTs decreased with the increase of the growth time mainly due to hydrogen etching. The growth of CNTs followed the tip growth mode.