Sulphur/halogen promoted oxidative dehydrogenation of hydrocarbons

Iodine is known to be an efficient promoter for the oxidative dehydrogenation of a wide variety of hydrocarbons. However, because of its high cost attempts have been made to reduce or eliminate it from the reaction system while still achieving high product yields. Theoretical considerations (thermodynamic and mechanistic) will be presented to show that it should be possible to use sulphur alone or together with chlorine and/or bromine in place of iodine or iodine/halogen mixtures in the oxidative dehydrogenation of different hydrocarbons. These considerations indicate that high product yields should also be possible with the new system if suitable catalysts are used.     

Firing of large intricately shaped Dinas products

Conclusions The large, complex-shaped Dinas refractory products for coke ovens should be fired in a specialized tunnel kiln equipped with burners (of the roof or wall type) which will ensure a high degree of firing uniformity. The effective height of the kiln charge should preferably be about 700 mm. The charge should be set up in well-spaced columns and the products should be placed predominantly on their ends. The lining of the floor of the kiln or kiln trucks should be constructed of lightweight refractories and heat-insulating materials.Complex-shaped Dinas products should be produced from compositions with a maximum grain size of 2 mm and the grain-size distribution given earlier in this article.The mineralizing additive should be ferrous lime with CaO/FeO=1.8/0.7, and the amount added to the composition should be 2.5±0.1%.To maximize the precision of the dimensions of the product and to minimize its aftergrowth the proportion of unconverted quartz should not exceed 2%. This condition can be ensured by using a fine-grained molding mix and the correct amount of an additive of the correct composition and by optimizing the firing conditions in the specialized kiln.Translated from Ogneupory, Vol. 18, No. 8, pp. 9–16, August, 1977.     

在塔设备设计中如何判断是否加框架支撑

高径比 (H/D)较大的塔在风载荷的作用下 ,在塔顶处会引起一定的静挠度。因此在完成初步的塔设计后 ,还要验算塔设备的挠度值是否在允许的范围内 ,进而决定塔是否需要加框架支撑。本文通过实例中对塔的强度及挠度的计算 ,来判断是否加框架支撑。     

The mechanism for the cathodic delamination of organic coatings from a metal surface

A detailed mechanism of cathodic delamination from a defect in an organic coating is presented, which takes into account the reactants and how they get to the delaminating front. Oxygen and water pass through the organic coating whereas cations, at least in part, reach the front by lateral diffusion. Five means for minimizing cathodic delamination are suggested: (1) No bare metal, or superficially oxidized metal, should be present at the coating/substrate interface. (2) There should exist at the coating/substrate interface a layer which is a very poor conductor of electrons. (3) The interfacial layer at the coating/substrate interface should be a poor catalyst for the cathodic reaction. (4) The boundary between the substrate and the coating should be rough in order to provide a tortuous path for lateral diffusion. (5) The interfacial region should be resistant to alkaline attack.     

化学链反应器研究进展

化学链技术是目前能源技术研究的热点之一,其关键技术包括载体材料的制备和反应器的设计。综述了化学链技术的应用前景,总结了化学链反应器设计原理,回顾了目前世界上公开报道的设计完成、在建或已经运行的化学链反应器,归纳讨论了不同反应器设计细节的共同点及目的。开展以微小颗粒、纳米颗粒作为载体材料时,颗粒聚团在宏观反应器尺度下的流动传递规律、循环反应机理和系统运行控制特性的研究;开展反应器内颗粒流动-传递-反应耦合机制研究,建立多尺度统一模型;在全尺寸化学链反应器上进行系统自热实验研究;利用数值模拟方法研究和开发用于固体燃料转化过程的高效炭/灰分离器是未来化学链反应器发展需要关注的几个方面。     

对苯二甲酸加氢精制催化剂的研究进展

详述了对苯二甲酸加氢精制工艺用钯/活性炭(Pd/C)催化剂、非碳载体的Pd催化剂和多活性中心催化剂的研究进展;指出我国催化剂研究在抗磨损、抗硫性能、钯晶粒易长大等方面与国外的差距较大,今后应研发以二氧化钛、纳米碳等为新型载体制备的催化剂,进一步开发Pd/C催化剂以实现精对苯二甲酸工业化生产。     

AN EVALUATION OF ISOTHERMS IN THE DESCRIPTION OF COMPETITIVE ADSORPTION EQUILIBRIA

Since adsorption isotherm equations are widely used in the industry to model adsorption on substances like activated carbon, an investigation was done to determine the applicability of three of these equations, viz, the multi-component Freundlich, multi-component Langmuir and the isotherm equation proposed by Fritz and Schluender. Based on statistical thermodynamic principles a discrete adsorption model was recently proposed. This model was used to create sets of binary adsorption data with some non-ideal characteristics. These data sets were used to evaluate the isotherm equations

It was found that the Langmuir isotherm gave the best fits, except where the visible adsorption energy changes with the surface loading or where selective adsorption occurs. Under these conditions, the Freundlich equation or that proposed by Fritz and Schluender should be used. It is recommended that these equations should be used to model low coverage-low concentration regions, while the high coverage-high concentration regions should be modelled using the Langmuir isotherm if possible

Some recommendations are made in connection with the procedure to estimate parameters for these isotherm equations.     

我国氯碱企业应主动适应当前的宏观经济调控形势

分析了国家控制单位GDP能耗指标、不鼓励企业自建电站、水涨价对氯碱行业的影响。提出如下建议:有关投资者推迟或取消PVC树脂/氯碱新建或扩建计划项目,发展技术含量高、效益好的氯碱下游产品;引进及开发工业燃料电池技术,有效利用联产氢气,开发适合氯碱生产的耗氧阴极技术;氯碱企业采取节水措施,引进海水淡化新技术,联产包括溴素在内的化工产品,提高综合经济效益。     

The static contact angle hysteresis obtained by different experiments for the system PTFE/water

Different experimental methods have been used to determine the static contact angle hysteresis of the system polytetrafluoroethylene/water and the results compared. While the Wilhelmy plate method is not influenced by methodical variations, contact angles determined by the sessile drop and the pendant bubble methods vary with the drop or bubble diameter up to a minimal diameter d_K of the contact area with the solid. This condition seems to be a universal one and should always be checked to ensure that the measured values are comparable. Contact angles calculated from the geometrical parameters of a drop or bubble should be used with care. The surface energetic characters for the PTFE/water are δθ = 19.5°, θ_{a, e} = 108.5° and θ_{r, e} = 89°.     

氯丙烯环氧化反应器气相安全控制条件

在相转移法氯丙烯环氧化反应过程中,由于少量双氧水发生无效分解生成氧气,导致反应器气相存在燃爆危险性。测试了工况条件下氯丙烯-氧-氮三元体系的燃爆特性,得出该体系的极限氧浓度值(LOC)为10.9%;考察了主要因素对气相氧浓度的影响。研究发现,要降低气相氧浓度,应尽可能降低催化剂用量,适当提高搅拌速度,严格控制H_2O_2用量;应在液相沸腾后开始H_2O_2进料,并控制反应初始阶段的H_2O_2进料量,以避免瞬间H_2O_2进料过快。     

MXenes and MXene-based (nano)structures: A perspective on greener synthesis and biomedical prospects

Generally, MXenes have been widely prepared using hazardous/harmful etchants or fluoride-containing reagents through laborious protocols without environmentally-friendly features. Thus, greener and eco-friendly techniques with mild conditions and safer agents/materials for the synthesis and functionalization of these structures should be focused to reduce or avoid the utilization of toxic and hazardous chemical agents, enhancing the biocompatibility and biosafety criteria. The manufacturing of high-quality MXenes and their derivatives with up-scalability, simplicity, high yields, and cost-effectiveness advantages for clinical and biomedical purposes should be a priority for research in this field. MXenes with unique electronic/electric, mechanical, thermal, optical and magnetic properties can be applied to improve the efficacy and functionality of intelligent nanosystems targeted for biomedical purposes. However, in addition to the up-scalability and environmentally-benign criteria, other critical aspects regarding the stability and cost-effectiveness as well as optimized conditions and functionalization processes should be addressed. Herein, recent advances of greener synthesis approaches for designing MXenes as well as their biomedical potentials are deliberated, focusing on important challenges and future perspectives.     

Perspectives in gas—liquid reactions

Gas—liquid reactions are of great industrial, biological, physiological, and ecological importance. This subject has acquired some maturity but there is still great scope for further investigations which are academically exciting and industrially relevant. There is a need to investigate some typical gas—liquid reactions under super—critical conditions. The beneficial effect of addition of another immiscible liquid, which shows relatively very high solubility for the solute gas, should be examined. The phase transfer catalysis in gas-liquid-liquid (or solid) should be studied. Gas-liquid reactions which occur in diffusion film in macromolecular systems need to be studied systematically. The desorption of a volatile intermediate product in fast/instantaneous gas—liquid reactions requires a careful study. The separation of acidic/basic mixtures by dissociation extraction in gas-liquid-liquid (or solid) system should be investigated. The role of solid particles smaller than diffusion film thickness in three phase reactions should be closely examined.Membrane processes are likely to be very attractive and there is a need to study facilitated transport and liquid membranes with industrially important systems.The role of micro-mixing in producing undesirable byproducts in mechanically agitated and gas sparged reactors has not received attention despite its importance. The simulation of large size absorber-reactors and desorber-reactors should be undertaken.     

阻火器的应用--燃烧炉/火炬系统的安全防范措施

介绍了阻火器的应用范围及要求,说明了欧洲标准94/9/EG对生产中有易燃、易爆气体时相应的安全措施,并针对燃烧炉/火炬系统的安全防范提出了液压阻燃、管道爆燃/爆轰阻火器以及安全喷嘴的使用要求,以确保阻火器正确选型、安装和维护。     

饮用水总硬度去除需求分析及控制目标探讨

饮用水总硬度及其所引起的"水垢"问题是近期人们关注的热点水质问题之一.论文基于我国水源水中总硬度的分布情况及离子组成比例,总结了Ca2+、Mg2+、典型阴离子、总溶解固体(TDS)对人体健康的影响.结合国内外针对总硬度限值的控制要求,综合饮用水主要用途、管道输送以及优质(舒适)水的供给需求等方面的内容,探讨了我国饮用水...     

Fertility-Sparing Approach in Women Affected by Stage I and Low-Grade Endometrial Carcinoma: An Updated Overview

Endometrial cancer (EC) is a deleterious condition which strongly affects a woman’s quality of life. Although aggressive interventions should be considered to treat high-grade EC, a conservative approach should be taken into consideration for women wishing to conceive. In this scenario, we present an overview about the EC fertility-sparing approach state of art. Type I EC at low stage is the only histological type which can be addressed with a fertility-sparing approach. Moreover, no myometrium and/or adnexal invasion should be seen, and lymph-vascular space should not be involved. Regarding the pharmaceutical target, progestins, in particular medroxyprogesterone acetate (MPA) or megestrol acetate (MA), are the most employed agent in conservative treatment of early-stage EC. The metformin usage and hysteroscopic assessment is still under debate, despite promising results. Particularly strict and imperious attention should be given to the follow-up and psychological wellbeing of women, especially because of the double detrimental impairment: both EC and EC-related infertility consequences.     

Process-water residues in fireclay and magnesia refractory production

Conclusions Particle size analyses of process water residues from fireclay and magnesia refractory production enable settlement rates to be established within water cleaning plant.From wet volume tests on residues it is possible to work out sludge volumes and cleaning cycle times for settlement plantl.Residues consisting of grog, magnesite, chromite, magnesite-chromite mixtures, and grog-clay mixtures with seven-tenths grog or over, should be removed mechanically from a horizontal settling tank after 1 day or longer, e.g., with a bucket crane or similar mechanism. A clay residue should be pumped out, but if it stands for 2 days or more it may be dug out.A coagulated residue of clay or a clay-grog mixture with seven tenths clay or more should be pumped out, but a 73 clay-grog mixture can be removed mechanically after settling for 3 days.Coagulated grog, magnesite, or chromite residues can be moved hydraulically for the first day, but if they stand longer they must be moved mechanically. If sludge is to be moved mechanically from a settling tank the clean water over it must be removed first, and appropriate equipment must be allowed for. If a sludge is to be removed hydraulically it must first be stirred up in some way.Translated from Ogneupory, No. 2, pp. 11–16, February, 1969.     

Soy protein in feeding the elderly

Protein needs of the elderly may be moderately higher than those of younger adults when expressed as a percentage of total calories. Most experts recommend an intake of ca. 0.8 g protein/kg/day or ca. 12–15% of the total calories. Soya protein appears to be as good as animal protein in meeting the amino acid and protein needs of adult humans when consumed in adequate quantities. Attention must be given to the appropriate heat treatment and processing of soybeans to inactivate non-nutritional factors. The mineral and vitamin content of the diet should be monitored, because some of these nutrients may be altered or removed in the preparation of soya protein fractions or isolates for use in food products. Further research is needed to fully identify the nutritional requirements of the elderly, especially as affected by disease, trauma and drugs. In addition, nutrient interaction and bioavailability should be studied in foods which are processed by new techniques.     

低速纺制8.3tex三角异形有光PET长丝——Ⅰ.前纺工艺研究

用VC403纺丝机纺制题示纤维。对设备及工艺进行了改进:在切片干燥前加入0.01%的硬酯酸钙,以增加切片的润滑性能;干燥升温阶段放慢升温速率,冷却阶段通入减湿空气。在切片含水率≤0.006%的情况下,纺丝温度应控制比同规格半消光PET高8—12℃;吹风温度为40—50℃,吹风速度0.2—0.3m/s;加强喷丝板保温;改进吹风窗结构及设计水字形喷丝孔形。     

细旦PA66高强型长丝的研制与开发

采用意大利Leonard公司EM105F挤出机,改造后的VCA21纺丝机,探讨了利用相对分子质量为 14 000的PA66或切片通过高倍拉伸生产出细旦PA66高强长丝(FDY-HT)的工艺技术。结果表明:纺丝速度控制在300m/min,卷绕丝剩余伸长率450％,后加工过程中拉伸倍数大于5．0、拉伸温度160-180℃,可制得55 dtex/17 f,78 dtex/23 f,110 dtex/34 f PA66 FDY-HT产品。为保证可纺性,应选择性能良好的金属粉作为纺丝组件过滤材料,适当提高卷绕丝油剂含量。     

Fat emulsions. Effect of polyoxyethylene and alkyl content of emulsifiers on stability to sterilization

Summary When a given system of emulsifiers of known compositions and molecular weights was employed, it was found that in order for fat emulsions of 15% oil content to be stable to the heat required for sterilization, the emulsifiers must meet definite requirements. Minimum weight percentage of total lipophilic groups should be 0.29%; minimum weight percentage of total hydrophilic groups should be 0.57%; the polyoxyethylene groups of emulsifiers containing such groups should account for at least 70% of the mole weight of these emulsifiers; the lipophilic/hydrophilic ratio should be about 0.5. The minimum content of lipophilic and hydrophilic groups was found to be an additive total of these groups as provided by the complete emulsifying system whether composed of individual or multiple emulsifying agents and whether of similar or dissimilar functional groups. With the emulsifiers used, an acyl group greater in length than 12 carbon atoms was found to be necessary to prepare cottonseed oil emulsions which were stable to heat. Resistance of emulsions to breakage by mechanical shock was imparted by a rather large amount of lipophilic groups, so that the lipophilic/hydrophilic ratio was 1 or over. Presented at fall meeting of American Oil Chemists' Society, Cincinnati, O., September 30–October 2, 1957. This work was supported in part by funds from the Office of the Surgeon General, U. S. Army. One of the laboratories of the Southern Utilization Research and Development Division, Agrciultural Research Service, U. S. Department of Agriculture.