混合金属络合物羟基镍铝交联蒙托土的表面酸性及催化性能

用NH_3-TPD,IR技术研究了混合金属络合物羟基镍铝交联蒙托土的表面羟基和表面酸性。考察了制备方法、Al/Ni比对其表面酸性的影响,同时用异丙苯裂解反应表征了其催化性能。结果表明,交联蒙托土存在L酸和B酸,其中以L酸为主。表面酸性可能来源于柱子和表面羟基,柱子的热稳定性对表面羟基,表面酸性均有较大影响。Ni的引入增加了L酸和B酸,取代法制备的样品具有比共聚法的样品更强的酸性。交联蒙托土具有较好的异丙苯裂解性能,Ni的引入使其活性有较大的增加。     

V－Ag－Ni系氧化物的表面氧性质与甲苯选择性氧化的催化性能

制备了一系列Ｖ、Ａｇ、Ｎｉ原子比不同的三元氧化物，应用ＴＰＤ－ＭＳ技术研究了样品表面氧的性质，并测定了甲苯选择性氧化生成苯甲醛的催化活性．实验结果表明，样品表面存在有多种吸附的氧物种．在脱附温度＜９００℃：当Ｎｉ含量对Ａｇ（或Ｖ）的原子比为０．２５或０．５０时，仅在低温处出现有表面的Ｏ－和Ｏ２－两种氧物种的脱附峰；当Ｎｉ含量对Ａｇ（或Ｖ）的原子比增高到＞０．７５时，除有表面的Ｏ－和Ｏ２－两种氧物种的脱氧峰外，还有由于样品中的物相转变所生成的有晶格氧（Ｏ２－）参与脱附的脱氧峰．随着Ｖ－Ａｇ中Ｎｉ含量的改变，脱氧峰的脱附活化能Ｅｄ值也发生变化，３＃样品（Ｖ：Ａｇ：Ｎｉ＝１：１：０．７５）的Ｅｄ值最低，生成苯甲醛的选择性也最高．因此，样品的Ｅｄ值与生成苯甲醛的选择性之间存在着顺变关系．     

表面增强拉曼光谱研究吸附态的变化

测量了吡啶分子在电化学处理的银表面和亚甲基蓝分子在硝酸刻蚀银表面的表面增强拉曼光谱（ＳＥＲＳ）．对ＳＥＲＳ谱线的分析结果表明，吡啶分子在较低的表面吸附分子密度时倾向于平躺方式；而在较高的表面分子密度时，则倾向于向垂直吸附态转化．亚甲基蓝分子在较低浓度时主要是平躺吸附，随Ｃｌ－浓度的增加，亚甲基蓝从“平躺”吸附态转向“站立”吸附态．     

担体对Fe-MnO催化剂CO加氢合成烯烃性能影响的TPSR表征

考察了不同担体担载的Ｆｅ－ＭｎＯ催化剂上ＣＯ加氢合成烯烃的反应。结果表明担体直接影响低碳烯烃选择性。通过对催化剂的ＣＯ，ＣＯ／Ｈ２，Ｃ２Ｈ４等吸附的ＴＰＳＲ表征及催化剂表面ＣＯ加氢微观反应的研究，证明以碱性担体为基质的ＰＢＣ催化剂具有强吸附ＣＯ能力，且生成的烯烃不易发生二次反应，因而ＰＢＣ催化剂具有较高的烯烃选择性；以酸性担体为基质的ＰＡＣ催化剂对ＣＯ为弱吸附，对Ｈ２为较强吸附，且烯烃会发生强烈的     

Production of Raw Starch-Saccharifying Thermostable and Neutral Glucoamylase by the Thermophilic Mold <Emphasis Type="Italic">Thermomucor indicae-seudaticae</Emphasis> in Submerged Fermentation

Among physical and nutritional parameters optimized by “one variable at a time” approach, four cultural variables (sucrose, MgSO₄ ^.7H₂O, inoculum size, and incubation period) significantly affected glucoamylase production. These variables were, therefore, selected for optimization using response surface methodology. The p-values of the coefficients for linear effect of sucrose and inoculum size were less than 0.0001, suggesting them to be the key experimental variables in glucoamylase production. The enzyme production (34 U/ml) attained under optimized conditions (sucrose, 2%; MgSO₄ ^.7H₂O, 0.13%; yeast extract, 0.1%; inoculum size, 5 × 10⁶ spores per 50 ml production medium; incubation time, 48 h; temperature, 40°C; and pH 7.0) was comparable with the value predicted by polynomial model (34.2 U/ml). An over all 3.1-fold higher enzyme titers were attained due to response surface optimization. The experimental model was validated by carrying out glucoamylase production in shake flasks of increasing capacity (0.25–2.0 l) and 22-l laboratory bioreactors (stirred tank and airlift), where the enzyme production was sustainable. Furthermore, the fermentation time was reduced from 48 h in shake flasks to 32 h in bioreactors.     

Alkylation of catechol with methanol to guaiacol over sulphate-modified zirconia solid acid catalysts

A series of sulphate-promoted ZrO₂ solid acid catalysts with different contents of SO₄ ²⁻ were calcined at 450°C in air for 4 h and tested for the liquid-phase alkylation of catechol to guaiacol in a fixed-bed down-flow reactor. The 5 wt.% SO₄ ²⁻ on ZrO₂ showed the best conversion (82%) and selectivity for guaiacol (84%) at 200°C and 1 bar pressure. A smooth correlation was observed between the catalytical activity and surface acidity of sulphated zirconia. Based on our results, a surface mechanism is proposed.     

Statistical Optimization for Succinic Acid Production from E. Coli in a Cost-Effective Medium

Response surface methodology (RSM) was employed for optimization of medium components and cultural parameters in cost effective cane molasses based medium for attaining high yield of succinic acid. The important factors obtained by “one-variable-at-a-time-approach” (cane molasses, corn steep liquor, sodium carbonate, and inoculum density) were further optimized by RSM. The optimum values of the parameters obtained through RSM (cane molasses 12.5%, corn steep liquor 7.5%, and sodium carbonate 25 mM) led to almost double yield of succinic acid (15.2 g/l in 36 h) as against “one-variable-at-a-time-approach” (7.1 g/l in 36 h) in 500-ml anaerobic bottles containing 300-ml cane molasses based medium. Subsequently, in 10-l bioreactor succinic acid production from Escherichia coli was further improved to 26.2 g/l in 30 h under conditions optimized through RSM. This fermentation-derived succinic acid will definitely help in replacing existing environmentally hazardous and cost-intensive chemical methods for the production of succinic acid.     

Effect of specific adsorption of anions on the kinetics of the current relaxation after pulsed anodic activation of dissolution of hydrophilic metals

Based on the model of spatial separation of the dissolution and passivation of hydrophilic metals, the effect of strong specific adsorption of anions on the shape of curves for the relaxation of anodic current of metals in acid solutions after switching an anodic activation pulse off is considered by using iron as an example.     

模板沉淀法制备高比表面积MnOx-CeO2催化剂及其CO低温氧化活性

以十六烷基三甲基溴化铵(CTAB)为模板剂, Ce(NO3)3和Mn(NO3)2为前驱体, 通过沉淀法制备了一系列晶粒小于5 nm的高比表面积MnOx-CeO2催化剂, 并考察了催化剂的CO氧化反应性能. 采用XRD、Raman光谱、TPR和N2气吸附脱附等手段对催化剂的比表面积、晶粒大小和物相组成进行了表征. 当Mn摩尔分数≤34%时, 催化剂的比表面积在160~170 m2/g之间; 当锰含量进一步提高后, 催化剂的比表面积呈下降趋势. 当Mn摩尔分数≤34%时, XRD只检测到CeO2物相, 而Raman光谱则检测到α-Mn2O3的存在. 催化剂上表现出较好的CO氧化活性, 这主要归因于高比表面积. 随着锰含量的增加, 催化剂的轻化频率(TOF)下降, 表明高分散、小晶粒的氧化锰物种是催化剂的活性物种. H2-TPR结果表明, 催化剂的CO氧化活性还与催化剂中高价锰物种有关. 焙烧温度升高使催化剂的晶粒增大、比表面积减小, 同时催化剂中锰的平均价态降低, 导致CO氧化活性下降.     

纳米CaCO3的改性、表面结构与流变行为研究

采用铝锆偶联剂和棕榈酸改性纳米CaCO₃ 粉体. 借助 XRD, FTIR, 接触角及流变学等测试方法对纳米CaCO₃ 的表面结构进行表征. XRD 分析表明: 改性纳米 CaCO₃保持原样品完整的体相结构, 为方解石型纳米微晶. FTIR 分析证明: 表面改性剂与纳米 CaCO₃ 表面是以化学键合和物理吸附方式相结合, 粒子表面存在羧基等有机官能团的红外吸收特征. 通过测定苯和水在改性纳米CaCO₃粉末压片上的接触角, 计算了改性纳米 CaCO₃的表面能和极性分量, 并与未改性纳米CaCO₃ 进行比较. 结果表明, 经表面改性, 纳米 CaCO₃ 的表面能和极性分量明显降低, 其在有机溶液中的吸附功增大, 界面张力大大降低; 经棕榈酸改性的纳米 CaCO₃ 表现出较好的亲油疏水性, 而铝锆偶联剂改性的纳米 CaCO₃ 同时具有亲水性和亲油性. 以液体石蜡为溶剂, 研究了表面改性对纳米CaCO₃悬浮液流变行为的影响. 实验发现: 经过表面处理, 纳米 CaCO₃ 粉体悬浮液流变行为发生较大的变化, 稳态剪切黏度大大降低, 表现出较小的动态弹性储能模量和黏性损耗模量, 而损耗因子较大.