A_1-A_2-O-M工艺处理焦化废水的实验研究

采用厌氧-缺氧-好氧-复合(A1-A2-O-M)工艺处理焦化废水,考察了外加碳源和碱源对焦化废水COD和NH4+-N脱除效果的影响。试验结果表明:外加甲醇和碳酸氢钠对焦化废水的硝化和反硝化效果影响很小;不外加碳源和碱源时,焦化废水经处理后出水的COD和NH4+-N平均质量浓度分别为125.0mg/L和1.12mg/L,分别达到《污水综合排放标准》(GB8978-1996)中的二级标准和一级标准。     

低(等)压合成氨的最佳H2/N2与催化活性的关系

采用高压催化剂性能评价实验装置，在压力分别为7.0,10.0和15.0MPa，温度分别为350,400和450℃条件下，在H2／N2为1.6-3.0范围内研究了H2／N2对A301，ZA－5和A110－2型催化剂的活性和合成塔出口氨浓度的影响。在压力和空速一定的条件下，最佳H2／N2随反应温度而异。在350，400和450℃下，最佳H2／N2分别为1.8-2.2,2.2-2.5和2.5-3.0。由此可见，合成氨反应的速率达到最大值时的最佳H2／N2值与反应的进程有关。为此提出了催化剂效率K（Catalysis efficiency)的概念来表征在催化剂作用下反应器出口氨浓度趋近平衡的程度，即K＝CNH3／C^*NH3。根据实验结果，得到了最佳H2／N2与催化剂效率的定量关系：（H2／N2）m=1.5(1 CNH3/C^*NH3)=1.5(1 K)。由此可以根据催化剂在不同反应条件下的催化剂效率来确定最佳H2／N2。凡是会降低催化剂效率的因素，都会使最佳H2／N2降低。各种影响因素对最佳H2／N2的影响中，反应温度的影响最大，其次是空速和催化剂的活性，而压力和惰性气体含量的影响相对较小。在低温（低压）下合成氨，宜采用较低的H2／N2。     

湿式氨法脱硫工艺及应用

随着二氧化硫对环境的污染越来越严重,国家环保总局对烟气二氧化硫排放控制严格,烟气脱硫显得日益重要。简单介绍了湿式氨法烟气脱硫技术的工艺流程及实际应用情况。湿式氨法脱硫工艺具有原料易得、脱硫塔不易结垢、不产生废水、副产品硫酸铵可作为农用肥料,减少了对环境的二次污染等特点,是较适合我国国情的烟气脱硫技术。     

15万t/a双甲氨合成联合装置设计

从工艺路线的比较、压力等级的选择、主要设备的选型等方面阐述了双甲氨合成联合装置的设计特点。结合生产运行实践,分析了双甲氨合成工艺路线的运行参数,与采用不同工艺的生产消耗和产品成本进行了对比。结果表明,该工艺吨氨节约成本80元,精醇成本为1112.6元/t,经济效益显著且生产运行稳定。     

探讨回收污水中有用的物质

重油催化裂化等的污水含汽油、硫和氨，将汽油、硫和氨回收是哈尔滨石化分公司具有发展前景的项目。     

90年代合成氨工艺技术的新进展

介绍了国外９０年代合成氨生产技术的研究开发和工业化应用进展情况，重点讲述了Ｋｅｌｌｏｇｇ公司，Ｌｉｎｄｅ公司和ＩＣＩ等公司开发的新工艺。     

负载型钴铜双金属氮化物催化氨分解研究

Co and Mo bimetallic nitrides supported on Mg（Al）O, MgO and γ-Al2O3 were prepared in temperatureprogrammed reactions with NH3. The surface morphology, chemical composition and catalytic activity for NH3 decomposition on the supported Co and Mo bimetallic nitrides were studied by X-ray diffractometer （XRD）, NH3 temperature-programmed desorption and mass spectrometer （NH3-TPD-MS）, temperature-programmed desorption and mass spectrometer （TPD-MS）, H2 temperature-programmed surface reaction （H2-TPSR） and activity test. The phases of Co3Mo3N and MoN could be formed on Mg（Al）O, MgO and Al2O3 during the nitridation, and they might be more uniformly dispersed on Mg（Al）O and MgO than on γ-Al2O3. Transition metallic nitrides are generally considered as potential catalysts for hydrogen-involving reactions due to the entrance of hydrogen atoms into subsurface and the lattice of metallic nitrides. The diffusion of nitrogen in the bulk and the structure transformation of Co and Mo nitride compounds occur during NH3-TPD, but the supported Co and Mo bimetallic nitrides are not easily reduced at H2 atmosphere. Co3Mo3N/Mg（Al）O catalyst exhibits the highest activity, while Co3Mo3N/Al2O3 exhibits the lowest activity for NH3 decomposition. Furthermore, the catalytic activity of Co and Mo bimetallic nitrides is not only much higher than that of supported single metallic nitride, but also highly dependent upon the surface acidity and BET surface area of support.     

The influence of soil properties on the effectiveness of phenylphosphorodiamidate (PPD) in reducing ammonia volatilization from surface applied urea

Urea can be an inefficient N source due to rapid hydrolysis by soil urease leading to NH₃ volatilization. The current study investigated the effect of the urease inhibitor phenylphosphorodiamidate (PPD) incorporated at two concentrations (0.5% and 1% w/w) within the fertilizer granule on NH₃ volatilization from surface applied urea. The daily rates of NH₃ loss from 20 soils of widely differing properties from Northern Ireland were measured over 14 days using ventilated enclosures under simulated spring conditions. Cumulative loss rates were calculated and fitted to a logistic model from which total NH₃ loss (Amax) and the time to maximum rate of loss (Tmax) were determined. Stepwise multiple linear regression analysis related the effectiveness of PPD in reducing NH₃ volatilization from urea to soil properties.The total cumulative loss of ammonia from unamended urea varied from 0.37 to 29.2% depending on soil type. Ammonia volatilization appeared to be greatest on a soil with a high pH (R² = 0.65), a low titratable acidity (TA) (R² = 0.63) and a soil that was drying out (R² = 0.50). Soil pH was negatively correlated with TA (r = –0.826, P < 0.001) suggesting that soils with a low TA may have received recent lime. Including cation exchange capacity (CEC) and % N as well as pH-KCl in the multiple linear regression equation explained 86% of the variance.The effectiveness of PPD in reducing Amax varied between 0% to 91% depending on soil type, the average over all 20 soils being 30 and 36% for 0.5% and 1% PPD respectively. The most important soil properties influencing the effectiveness of the urease inhibitor were soil pH-H₂O and TA accounting for 33% and 29% of the variance respectively. PPD was less effective on a soil with a high pH and low TA. These were the soil conditions that led to high NH₃ volatilization from unamended urea and may explain why PPD had limited success in reducing ammonia loss on these soils. Multiple linear regression analysis indicated that 75% of the variation in the % inhibition of NH₃ loss by PPD could be significantly accounted for by pH-H₂O, initial soil NO ₃ ^- -N concentration, % moisture content and % moisture loss.The delay in Tmax by PPD ranged from 0.19 to 7.93 days, the average over all 20 soils being 2.5 and 2.8 days for 0.5% and 1% PPD respectively. TA, % moisture content, urease activity and CEC were soil properties that significantly explained 83% of the variation in the % delay in Tmax by PPD in multiple linear regression analysis. However, none of these soil properties were significant on their own. As urea hydrolysis occurs rapidly in soil, delaying Tmax under field conditions would increase the chance of rain falling to move the urea below the soil surface and reduce NH₃ volatilization. A urease inhibitor should be more effective than PPD on soils with a high pH and low TA to be successful in reducing high NH₃ losses.     

Emission of excited potassium species from an industrial iron catalyst for ammonia synthesis

The angular dependence of potassium emission-desorption is studied from a fused iron catalyst of the type used for ammonia synthesis. The excited species (K^*, K _n ^* , etc.) and positive ions K⁺ have strongly different angular distributions. The bilobular distribution measured for ion desorption is concluded to be either due to excited atoms, so-called Rydberg atoms, or excited clusters. Both types of species have to desorb from the edges of the sample and become field ionized and deexcited just outside the sample, as reported in previous studies on an iron oxide catalyst. The peak in the normal direction measured for excited species is due to excited cluster formation outside the catalyst surface. Similarities with previous results for other catalysts are observed. The possibility that the promoter function of potassium in the ammonia synthesis is due to excited species is pointed out.On leave from Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Cracow, Poland.     

正丁醇水溶液通氨气法制备TiO2粉体

以TiCl4为原料,正丁醇和水的混合液为溶剂,通入氨气促使TiCl4水解,制备出不同粒径的TiO2粉体.由X射线衍射、场发射扫描电镜和激光粒度仪对样品进行了表征.研究了温度、pH值对粉体的晶型、形貌和粒径的影响.结果表明:在80 ℃通氨气,3≤pH≤8时,所得TiO2粉体均为锐钛矿和金红石的混相,且pH=3时制得的粉体为60 nm左右的球形颗粒,分散性很好;而pH=6,8时所得的粉体团聚严重;室温(20～30 ℃)下通氨至pH=6也可得到分散性较好的无定型态TiO2粉体,但粉体粒径增大,约170nm左右.