活化硼氢化钠在有机合成中的应用

介绍了有机合成反应中NaBH4与添加剂共同作用的反应,其中包括烯烃和炔烃的还原,羧酸的还原,氨基酸及其衍生物的还原,羧酸酯的还原,酰胺的还原,腈基的还原,酰氯的还原,硝基化合物的还原,醛酮的还原等。与LiAIH4的还原相比较,其反应条件更温和,反应过程更安全、易操控、易放大。     

费托合成催化剂还原技术研究

费托合成工艺能否成功运行的关键因素之一为催化剂及其还原工艺的选择。本文简要介绍了费托合成催化的种类及其应用领域。详细介绍了催化剂还原过程,包括催化助剂的影响、还原过程的晶态结构演化、还原动力学以及还原工艺。最后重点介绍了还原气氛、还原空速、还原温度以及还原压力等还原参数对费托催化剂合成性能的影响。结果表明:催化剂的还原过程呈现明显的多相还原复杂行为,合理的助剂添加和还原参数选择有利于提高催化剂的还原性、活性和产品选择性。     

流化床中铁矿粉预还原条件对终还原影响的实验研究

在石英流化床中研究了铁矿粉的预还原和终还原行为,考察了预还原温度和时间对终还原过程的影响,通过对预还原和终还原产物表面形貌的观察,分析了预还原条件对铁矿粉终还原的影响规律. 结果表明,温度对还原速率和产物层结构有重要影响,预还原度随还原温度提高而增加,但终还原度有波动,较理想的预还原温度为973 K,终还原度可达80.4%. 在一定条件下缩短预还原时间不利于铁矿粉预还原,但有利于终还原.     

Ф1000氨合成塔触媒的升温还原

云天化云峰分公司Ф1000氨合成塔大修后需要进行升温还原。阐述了升温还原的准备工作,升温还原分层还原措施,分层还原的控制,还原的判别标准,以及轻负荷生产。开车后生产运行较好。     

还原法制备石墨烯的研究进展及发展趋势

综述了还原法制备石墨烯的研究现状,主要介绍了金属还原、光催化还原、电化学还原、热还原、化学还原试剂还原等方法的研究进展,并指出了还原法制备石墨烯的发展趋势。     

对氯苯胺制备方法研究进展

综述了由对硝基氯苯还原制对氯苯胺的技术进展。涉及的还原方法有：金属粉还原、硫化物还原、电化学还原、一氧化碳还原、催化加氢还原、NaSeH还原、水合肼还原和光催化还原，评述了各种方法的优缺点．提出了应加强催化加氢和光催化还原的研究力度。有19篇参考文献。     

模拟工业还原气体对甲醇催化剂还原的影响

甲醇催化剂在使用前需要进行还原,大多数甲醇工厂采用氢气进行还原,少部分工厂采用焦炉煤气或转化气进行还原,整个还原过程的控制对后期催化剂性能有决定性的影响。采用不同还原气进行甲醇催化剂还原实验。结果表明,采用焦炉气还原的催化剂,初始Cu颗粒更大;采用H₂还原的催化剂能暴露更多的活性位点,甲醇合成性能更优。     

古陶瓷研究中的烧成气氛性质讨论

本文对陶瓷烧成气氛的性质进行了深入研究。研究结果表明：过去一些古陶瓷研究工作者将陶瓷制品还原比值的大小作为判断陶瓷烧成气氛性质的依据,并根据还原比值的大小将还原烧成气氛分为强还原气氛与弱还原气氛,以及根据烧成气氛中一氧化碳浓度的大小将还原气氛任意分为强还原气氛与弱还原气氛等都没有科学依据。为了说明陶瓷制品烧成过程中氧化铁还原成氧化亚铁的程度,本文提出了比还原比值更为直观的陶瓷制品还原率计算公式。     

铁基费托催化剂还原机理及动力学研究进展

费托合成技术是煤间接液化工艺过程中的关键技术,开发高活性、高产品选择性和高稳定性的催化剂是费托合成技术成功的最关键因素之一。论述了铁基费托合成催化剂的还原机理及还原动力学的研究进展,讨论了催化剂焙烧温度、还原H_2/CO比、还原压力和水分压对还原机理及还原动力学的影响规律。随催化剂焙烧温度升高,催化剂物相中超顺磁态的Fe~(3+)组分向顺磁态的α-Fe_2O_3组分转变,较高的焙烧温度导致催化剂晶格缺陷减少,晶粒尺寸增加,反应活化能和指前因子增加,催化剂的还原能力减弱。随还原气氛中CO分压的增加,催化剂的还原和碳化程度提高,催化剂表面形成更多的活性中心,催化剂活性升高。还原压力的升高促进了催化剂的还原和碳化,但过高的还原压力会抑制催化剂的还原和碳化。水分压对催化剂的还原路径没有明显影响,但水分压的增加对催化剂各还原步骤均有抑制作用,还原活化能增加。根据费托合成技术对铁基催化剂的性能要求,未来催化剂还原工艺的研究重点在于开发中温还原、合成气气氛下的低压催化剂还原工艺,以降低固定资产投资,缩短还原时间,提高催化剂的活性和稳定性,降低生产成本,提高企业竞争力。     

费托催化剂预处理工艺研究进展

还原工艺对于费托合成技术的成败具有极其重要的作用。简要介绍了各工业化费托技术使用的还原反应器,并对还原过程中规律性的结果,包括还原中催化剂晶态结构演化,还原气氛、还原温度对催化剂反应性能的影响进行了详细介绍。     

Sorption of sulphur dioxide by indoor surfaces III.—Leather

The sorption of sulphur dioxide by a wide range of leather samples has been investigated at a concentration of ～ 100 μg/m³ using sulphur-35 dioxide. In general, the sulphur dioxide was sorbed evenly over the leather surfaces, the sorbed sulphur being water-soluble. The position on the hide from which the leather was taken had no significant effect on the amount of sulphur dioxide sorbed. The total uptake of the gas was reduced by the application of a finish and by dyeing. The penetration of sulphur dioxides into the samples was influenced by the nature of the organic retanning process used, condensed tannins leading primarily to surface sorption. Leather greases were also shown to reduce penetration of sulphur dioxide. Some implications of these results in the degradation of leathers by atmospheric sulphur dioxide are discussed.     

The electrochemical oxidation of sulphur dioxide at porous catalysed carbon electrodes in sulphuric acid

The electrochemical oxidation of sulphur dioxide has been studied in sulphuric acid solution at porous carbon electrodes coated with catalysts consisting of aluminum-vanadium mixed oxides with traces of platinum.Catalyst activity and stability in acid electrolytes are determined by the preparation conditions and the V₂O₅: Al₂O₃ ratio.Potentiodynamic measurements were made for investigating the mechanism of the anodic oxidation of sulphur dioxide. When catalysts are present, sulphur dioxide is anodically oxidized at the porous carbon electrodes. Direct electron transfer from the sulphur dioxide to the anode takes place at low potentials, whereas at more positive potentials reaction takes place between the sulphur dioxide and the electrolytically produced surface oxides on the platinum.     

Nitric oxide reduction by carbon monoxide over calcined limestone enhanced by simultaneous sulphur retention

Nitric oxide reduction by carbon monoxide over calcined limestones is enhanced by the coexistence of sulphur dioxide over a temperature range pertinent to f luidized-bed combustion. This demonstrates that the reduction of nitric oxide formed in fluidized-bed combustion of coal is promoted by simultaneous sulphur retention under a staged air firing. Thermogravimetric analysis indicated that the enhanced reduction of nitric oxide was attributed to the increase in catalytic activity of the calcined limestones used partially for sulphur retention.     

Influence of phosphorus on sulphur capture during co-firing of sewage sludge with wood or bark in a fluidised bed

Interference from phosphorus on sulphur capture during co-firing of sludge with wood has been investigated in a circulating fluidised bed boiler. Chemical equilibrium analyses were performed on the combustion system to complement the experimental results. It was found that the relatively high content of phosphorus in municipal sewage sludge interferes with the sulphur capture by occupying calcium, which otherwise would be available for reaction with sulphur. This fact must be taken into account when sulphur capture strategies are decided for reduction of sulphur dioxide emissions from sewage sludge as an additional fuel.     

从第二次全国污染源普查数据分析硫酸行业10年的变化

介绍了第二次全国污染源普查硫酸行业开展相关工作的情况,对硫酸行业产污系数手册进行解读.与第一次全国污染源普查结果相比,第二次全国污染源普查硫磺制酸二氧化硫排污系数由1.47 kg/t下降到0.41 kg/t,硫铁矿制酸废水产生量和废水中砷含量也大幅降低,行业污染物减排工作取得较大成效.进一步分析了硫酸行业二氧化硫减排的...     

Characterisation of Oligosaccharides Released by Steam Explosion of Sulphur Dioxide ImpregnatedPinus Radiata

The nature of the solubilized oligosaccharides released from the softwood Plnus radiata by the steam explosion process in the presence or absence of sulphur dioxide are described in this paper. Steam explosion in the absence of sulphur dioxide (215δ, 3 min) resulted in partial solubilization of only the hemicelluloses (14.5 g of neutral sugars/100 g o.d. wood) to their respective oligomers, which ranged in degree of polymerization from 1 to at least 12. The effect of adding 2.5% sulphur dioxide to the substrate was to facilitate the removal and hydrolysis of both hemicellulose and cellulose components (29.5 g of neutral sugars/100 g o.d. wood) by acid catalysis. Steam explosion of the substrate at an elevated temperature of 248° in the presence of 2.5% sulphur dioxide, caused almost complete cellulose and hemicellulose solubilization, and subsequent degradation reflected in poor carbohydrate survival (24.7 g of neutral sugars/100 g o.d. wood). The addition of sulphur dioxide to the process results in enhanced hydrolysis of the solubilized material to mainly mono- and disaccharides. However, the acid reversion products such as isomaltose and gentiobiose are formed, although their effect on total fermentable sugar yield is very small. Under normal steam explosion conditions the acidic aldooligouronic acid hydrolysis products represent only about 6% of total soluble carbohydrate. Interestingly, some demethylation of 4–0-methyl-D-glucuronic acid residues were observed as a consequence of sulphur dioxide catalysis.     

The sorption of sulphur dioxide by indoor surfaces. IV. Flooring materials

The sorption of sulphur dioxide by a number of carpet and solid flooring material samples has been investigated at a concentration of 50 to 60 μg/m³ using ³⁵S-labelled sulphur dioxide. The amount of sulphur dioxide sorbed by the samples varied little with their chemical composition and was of such a magnitude as to suggest a low affinity of the surfaces for sulphur dioxide. The sorption of sulphur dioxide by artificial fibre carpet pile was shown to be significantly reduced by the application of dyes.     

Adsorption of sulphur dioxide on coal

A study was made of the feasibility of using coal as an adsorbent material for the removal of sulphur dioxide from stack gases emitted to the atmosphere by different industries. From preliminary results, it would appear that coal is to be favoured by a raw materials/cost-effectiveness ratio of 2:1. The work shows semi-quantitatively that the adsorptive capacity of sulphur dioxide on coal varies slightly from one coal to another and that when coal is used and re-used through numerous (?40) cycles, its effectiveness as an adsorbent for sulphur dioxide is not greatly reduced. Moreover, this research supports the view that the heating value, ash, sulphur content, etc. of most types of coal changes only slightly after repeated usage as an adsorbent for sulphur dioxide. If, as these findings indicate, coal can initially be used as a sulphur dioxide adsorbent prior to its use as a fuel, economic potential for commercial applications should be enhanced. Empirical equations, developed to correlate the adsorption-desorption characteristics of different coals, can be used as a basis for prediction and comparison by future investigators to further explore this research.     

锌精矿沸腾炉应用磨煤喷粉机环保开炉的生产实践

介绍了磨煤喷粉机环保开炉法在锌精矿制酸装置中的应用。通过用粉煤代替硫磺作为燃料升温,大大减少了开炉期间的二氧化硫排放。详述了升温程序和控制要点。生产实践表明,只要严格操作、控制合理的炉顶负压、加强焙烧系统与制酸系统的联系,沸腾炉开炉就有可能实现二氧化硫零排放。     

二氧化硫催化氧化新工艺

介绍了二氧化硫催化氧化生成三氧化硫的新工艺，其特点是反应温度低，采用有机溶剂洗涤，可得到较高的硫酸浓度，同时设备腐蚀小。该工艺有希望革新现有的硫酸生产工艺，尤其适用于处理二氧化硫的排放。