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.     

含防爆剂农用硝酸铵的感度研究

实验在169℃左右加热硝酸铵到熔融状态,加入防爆剂,冷却到室温,得到含防爆剂的硝酸铵。测试其摩擦感度、5 s延滞期爆发点、静电火花感度以及配成铵油炸药后的撞击感度、雷管感度。结果表明,含防爆剂硝酸铵较普通硝酸铵撞击感度从88%降到24%,摩擦感度降为0%,5 s爆发延滞期从462℃增加到474℃,静电火花感度和雷管感度无明显变化。     

Influence of Pt Loading on Al2O3 for the Low Temperature Combustion of Methanol with and Without a Trace Amount of Ammonia

Pt/Al₂O₃ catalysts with platinum contents of 0.1, 1.0 and 3.0 wt% were used for the low temperature combustion of methanol in the absence and the respective presence of a trace amount of ammonia. It is observed that ammonia inhibits the combustion of methanol, which is due to competition between methanol and ammonia for the same sites. For a fixed space velocity and without ammonia in the gas, the performances of the catalysts increase up to a Pt loading of 1.0 wt%. In the presence of ammonia, however, no upper limit of performance is observed with increased Pt content. The results are discussed in terms of both Pt–support interface and the Pt surface being active.     

氨分解制氢装置工艺设备的技术改造

介绍了氨分解制氢工艺设备的改进.改造氨汽化器,用蒸汽加热液氨替换电加热液氨;用电加热器直接加热氮气,使分子筛加热再生,改造净化系统.     

Chemical interactions between soil N and alkaline-hydrolysing N fertilizers

Chemical interactions between soil N and alkaline-hydrolysing N fertilizers labelled with¹⁵N were studied in the laboratory using twelve-irradiated soils. Fertilizer was recovered in the soil organic N fraction via the process of NH₃ fixation. NH₃ fixation at day 7 varied from 1.8 to 4.6% of the N added as aqua ammonia at 1000 mg kg^–1 soil. The amount of NH₃ fixed increased with increasing rates of application of NH_3(aq) and urea. The rate of NH₃ fixation decreased with time, with more than 55% of the total NH₃ fixation in 28 days occurring in the first week following application of 2000 mg urea-N kg^–1 soil. Soil pH and NH₃ fixation varied in response to N source, and increased in the order of di-ammonium phosphate 3 fixation, resulting in the release of unlabelled ammonium (deamination) and a real added nitrogen interaction in all but two of the soils studied. The release of NH ₄ ⁺ initially increased up to a pH of 7.5, was inhibited between pH 8.5 and 9.0, but increased thereafter. The balance (N_bal) between NH₃ fixation and deamination was either positive or negative, depending on the pH of the fertilized soil, which was directly related to N source and concentration for a given soil.     

Effect of Ammonia on Silicone Rubber-Glass Adhesion

The adhesion energy between silicone rubber and glass has been obtained from the Johnson, Kendall and Roberts' test. The specific effect of ammonia on the quasi-equilibrium value has been studied as a function of the degree of crosslinking of the elastomer. For PDMS networks with lower molecular weight between crosslinks, the effect is more pronounced but completely reversible. This has been related to the increase in the non-dispersive part of the surface energy of the silicone due to the imbibed ammonia. In incompletely crosslinked hydroxyl-terminated PDMS, ammonia has a catalytic effect and is responsible for chemical bonding between the unreacted hydroxyl groups of the PDMS and the hydroxyl groups on glass.     

Comparison of single and coastal superphosphate for subterranean clover on phosphorus leaching soils

Coastal superphosphate, a partially acidulated rock phosphate (PARP), is being considered as an alternative fertilizer to single superphosphate for pastures in high rainfall (> 800 mm annual average) areas of south-western Australia. The effectiveness of single and coastal superphosphate, as P fertilizers, was measured in two field experiments using dry herbage yield of subterranean clover (Trifolium subterraneum). The experiments were started in April 1990 and were terminated at the end of 1993. In the years after P applications, soil samples were collected each January to measure Colwell soil-test P, which was related to plant yields measured later on that year, to provide soil P test calibrations.Relative to freshly-applied single superphosphate, the effectiveness of freshly-applied coastal superphosphate and the residues of previously-applied single and coastal superphosphate were less effective in some years (from 3% as effective to equally effective), and up to 100% more effective in other years. This large range in effectiveness values in different years is attributed to different climatic conditions. Soil P test calibrations were different for soils treated with single or coastal superphosphate. The calibrations were also different for different yield assessments (harvests) in the same year, and in different years. Consequently soil P testing can only provide a very crude estimate of the current P status of the soils.     

合成油、合成氨联产技术进展

阐述了合成油的技术、MTG工艺技术数据及我国联醇工业的发展，根据合成油、合成氨、甲醇原料相近的特点，以及合成油、合成氨联产工艺技术开发及工业性试验的结果，分析论证了合成油、合成氨联产的可行性。     

液氨贮存设计分析

氨是生产含氮肥料及尿素的基本原料，为确保原料供应，必须设置其贮存设施。介绍了常温中压、降温低压和低温常压三种不同的液氨贮存工艺及其特点，并以某大型氨站设计为例，分析了液氨贮存工艺流程、主要设备、材料的选型和工艺参数的确定。