plants, not always at the same time．Chlorine has been valued as a bleach．or a raw material for the production of bleaching powder，as a disinfectant in water supplies and as a raw material for plastics and solvents manufacture. Caustic soda has been used in the production of soda-ash, soap, textiles, and as a very important raw materialin an incredible variety of chemical processes． 简介，在化学工业法杖是的各个时期，Cl2 和NaOH 两者的需求量均很,但是不幸的是,对于电化学工厂的操作人员来说,两者的需求量必总是相同。Cl2 可作为漂白粉或作为漂白粉的生产原料, 水供应的消毒剂,以及作为塑料和溶解剂知道的原料。苛性钠用于生产纯碱、肥皂和纺织品, 以及在多种化学过程中作为一种十分重要的原料。
A1l the electrolytic processes have in common the electrolysis of salt to give chlorine and sodium hydroxide. The vast maj ority of production electrolyses a solution of salt, but there are some significant plants that electrolyze molten salt to give liquid sodium and chlorine．These are used by industries that need the liquid sodium，mainly in the production of tetra-alkyl lead petroleum additives, though the petroleum additive companies are diversifying and other uses may appear. There are essentially three different types of cell used for aqueous electrolysis：mercury cells, diaphragm cells and membrane cells．Membrane cells are really the only technology that is viable for new capacity in modem plants，but a large amount of old capaciW stin exists and many companies have not found it economical to replace even their mercury cells, despite the environmental implications.
所有的电解有着共同之处，盐的电解生成Cl2 和NaOH。大多数生产过程是电解（盐的）水溶液，但是有些重要的工厂，电解熔融盐生成Cl2 和液态钠。这些电解熔融盐的过程用用于重要液态Na 的工业。虽然石油添加剂厂家多种多样，设会出现液态钠的其他用途，但是他的主要是用于生产四烷基铅石油添加剂。质上用于水溶液电解过程有三种不同的电解槽：水银槽、隔板槽和膜电解槽。膜电解槽只是用于此案在化工厂中新的生产过程，但是还存在着大量的旧生产过程，尽管说阴曹涉及到对环境的影响，但是许多生厂家上位法此案膜片电解槽代替水印电解槽的经济性。
All electrolytic reactions are based on the idea of using electons as a reagent in chemical Reactions. The basic reactions of brine electrolysis can be written as follows:
所有的电解反应都是以电子作为化学反应的试剂的观点为基础。设水电解过程的基本反应可写成下式：
This reaction has a positive free energy(△G=421. 7 kJ／mol at 25~C)and needs to be driven uphill by electricity．该反应的自由能为正，因此，需要电驱使进行。
Like many basic chemical processes，though the reaction appears to be gloriously simple. There are some significant complications.For a start．the reaction products need to be kept, apart ; hydrogen and chlorine will react explosively if they are allowed to mix. Chlorine reacts with hydroxide to give hypochlorous acid (HOCI) and chloride (both wasting product and creating by-products). The hypochlorous acid and hypochlorite(ClO`)in turn react to give chloratc(ClO3`), protons and more chloride．Hydroxide reacts at the anode to form oxygen．which can contaminate the chlorine. All the reactions reduce efficiency and/or create difficult separation or contamination problems that need to be sorted out bcfore any products can be sold．The key to understanding the various types of process used for the electrolysis is the way they separate the reaction products．There are basically three types of electrolytic cell for brine electrolysis, though there are many variations of detail among the cells from difierent manufacturers．
像其他许多化学品工艺一样，尽管该反应看起来似乎极其简单，但是有一些方面很复杂。首先，该反应的产物必须分开，如果H2 和Cl2 允许混合在一起，它们会剧烈反应。H2 和Cl2
反应生成HOCl 和氯化物（两者均会浪费产物、生成副产物）。接着，HOCl 和次氯酸盐反应生成氯酸盐（ClO3-）、质子和更多的氯化物。OH— 在阳极区反应生成能污染Cl2 的O2。所有的这些反应可降低效率和（或）引起分解困难或污染问题。因此, 在产物销售之前, 有必要对这些反应清理。理解各种用于电解过程的关键是各种类型的过程分离反应产物的方式。尽管不同的制造商所用的电解槽在细节方面有着多种改变, 但是用于盐水的电解过程的电解槽基本可分为以上三类。
4．The Uses of Chlorine and Sodium Hydroxide
Sodium hydroxide has so many chemical uses that it is difficult to classify them conveniently．One of the largest uses is for paper—making，where the treatment of wood requires a strong alkali．In some countries this consumes 20％of production．Another 20％ is consumed in the manufacture of inorganic chemicals such as sodium hypochlorite(the bleach and disinfectant)．Various organic syntheses consume about another fifth of the production．The production of alumina and soap uses smaller amounts.
NaOH 的用途之多，以致很难将它们方便地进行分类。最大的用途之一是用于造纸，造纸业中木材的处理需要强碱。有些国家造纸业中NaOH 的消耗占其产量的20%，另外的20%用于无机化学品（如，次氯酸钠、漂白粉和消毒剂）的生产种有机合成约消耗另外的15%，氧化铝和肥皂的生产需要少量的NaOH。。
Chlorine is widely used in a variety of other products．About a quarter of all production world-wide goes into vinyl chloride，the monomer for making PVC．Between a quarter and a half goes into a vmiety of other products．Depending on the country，up to 10％goes into water purification. Up to 20%goes into the production of solvents (methylchloroform, trichloroethene, ect. ) though many 0f these are being phased out because of the Montreal Protocol. About 10%world-wide goes into the production of inorganic chlorine -containing compounds. A very significant use in some country for the bleaching of wood pulp，though this is another use coming under environmental pressure.
Cl2 广泛用于其它各种产品的生产。在全世界范围内大约有1/4 的Cl2 用于生产氯乙烯（生产PVC 的单体）。1/4 至1/2 的Cl2 用于水的纯化。尽管因为《关于消耗臭氧层物质的蒙特利议定书》多种溶剂正在被逐步淘汰，但是仍有高达20%的氯气用于溶剂的生产（如甲基氯仿、三氯乙烯等）。全世界范围内，大约10%的Cl2 用于无机含氯的化合物的生产。尽管Cl2 用于漂白木材浆是来自环境压力的另一种途径，但是在一些国家Cl2 的十分重要的用途是用于木材浆的漂白。
UNIT 7
Dinitrogen makes up more than three-quarters of the air we breathe，but it is not readily available for further chemical use．Biological transformation of nitrogen into useful chemicals is embarrassing for the chemical industry，since all the effort of all the industry‘s technologists has been unable to find an easy alternative to this．Leguminous plants can take nitrogen from the air and convert it into ammonia and ammonium—containing products at atmospheric pressure and ambient temperature；despite a hundred years of effort，the chemical industry still needs high temperatures and pressures of hundreds of atmospheres to do the same job．Indeed，until the invention of the Haber process，all nitrogen—containing chemicals came from mineral sources ultimately derived from biological activity．
虽然N2 占我们呼吸的空气3/4 以上，但是氯气不容易用于进一步化学应用。对化学工业来说，N2 的生成有用化学品的生物转化反应难以实现，因为所有的工业技术人员的努力（或尝试）还没有找到该过程的简单其他方法。在常压和室温条件下，豆类植物能从空气中吸入N2 将之转化为NH3 以及含NH4-的产物。尽管（化学工艺师）花了一百年的精力，要实现上述转化，化学工业仍然需要高温和上百个大气压的压力。直到Harber 过程的发明，所有的含N 化学品都来自于有生物活性的矿物资源。
Essentially all the nitrogen in manufactured chemicals comes from ammonia derived from the Haber-base process. So much ammonia is made(more…produced), and so energy-intensive is the process, that ammonia production alone was estimated to use 3% of the World‘s energy supply in the mid-1980s．
基本上，所生产的化学品中所有的N（元素）都来自于Harber 法得来的NH3。NH3 的生产之大，（尽管因为氨分子较轻，生产的其它产品的量更大，但其生产的NH3 的分子数要多于其他任何化合物），以及该过程的能源是如此的密集，以致于据估计，在二十世纪八十年代NH3 的生产就消耗全世界能源供应的3%。
1,The first Haber Process Ammonia Synthesis 1、Harber 法合成NH3
Introduction. All methods for making ammonia are basically fine-tuned versions of the process developed by Haber, Nernst and Bosch in Germany just before the First World War．N2+3H2~--'-'-\
引言. 所有的生产NH3 的方法基本都是以Harber 法为基础，稍稍加以改变，该过程是由Harber、Nerst、Bosh 在德国于一战前开发出来的。N2 +3H2≒2 NH3
In principle the reaction between hydrogen and nitrogen is easy; it is exothermic and the equilibrium lies to the right at low temperatures. Unfortunately, nature has bestowed dinitrogen with an inconveniently strong triple bond，enabling the molecule to thumb its nose at thermodynamics. In scientific terms the molecule is kinetically inert, and rather severe reaction conditions are necessary to get reactions to proceed at a respectable rate. A major source of ―fixed‖ (meaning, paradoxically ―usefully reactive‖) nitrogen in nature is lightning, where the intense heat is sufficient to create nitrogen oxides from nitrogen and oxygen·
原则上，H2 和N2 间的反应很容易进行，该反应是放热反应，低温时平衡向右移动。所不幸的是，自然界赋予的N2 一个很强的叁键，这使得N2 分子不易受热力学因素的影响。用科学术语来说，该分子是动力学惰性的。因此，要使该反应以一定的速度进行，需要相当苛刻的反应条件。实际上，―固定‖（意思相互矛盾，―有用的反应活性‖）氦的一种主要来源是闪电过程，闪电时生产大量的热量，把N2 和O2转化为N2O.
To get a respectable yield of ammonia in a chemical plant we need to use a catalyst.
What Haber discovered-and it won him a Nobel prize--was that some iron compounds were acceptable catalysts. Even with such catalysts extreme pressures (up to 600 atmospheres in early processes) and temperatures (perhaps 400 V)are necessary 在化工厂中要得到可观的NH3 的转化率，我们有必要使用催化剂。Harber 发现的催化剂（这使他获得诺贝尔奖）。是一些价廉的含铁的化合物。即使有该催化剂，这反应也需要很高压力（早期高达600 个大气压）和高温（大约4000C）
Pressure drives the equilibrium forward，as four molecules of gas are being transformed into two. Higher temperatures. However, drive the equilibrium the wrong way，though they do make the reaction faster、chosen conditions must be a compromise that gives an acceptable conversion at a reasonable speed. The precise choice will depend on other economic factors and the details of the catalyst. Modem plants have tended to operate at lower pressures and higher temperatures (recycling unconverted material) than the nearer-ideal early plants, since the capital and energy costs have become more significant．
因为四个气体分子转化为两个气体分子，所以增加压力使平衡向右（正方向）移动。然而，尽管高温使反应速度加快, 但是高温使平衡向右移动, 因此，所选的条件必须要折中的能以合理的速率得到令人满意的转化率。条件的准确选择将取决于其他的经济因素和催化剂的具体情况。因为资本和能耗费用越发重要，当代的工厂已经趋向于比早期工厂在更低的压力和更高的温度（循环使用未转化的物料）下进行操作。
Biological fixation also uses a catalyst which contains molybdenum(or vanadium)and iron embedded in a very large protein．the detailed structure of which eluded chemists until late 1 992．How it works is still not understood in detail.
氮的生物固定也使用了一种催化剂，该催化剂镶在较大的蛋白质分子中含有钼和铁，其详细结构直到1992 年才被化学家弄清楚，该催化剂的详细作用机理尚未清楚。
Raw materials．The process requires several inputs：energy，nitrogen and hydrogen．Nitrogen is easy to extract from air，but hydrogen is another problem．Originally it was derived from coal vi coke which can be used as a raw material(basically a source of carbon)in steam reforming．where steam is reacted with carbon to give hydrogen，carbon monoxide and carbon dioxide．Now natural gas(mainly methane)is used instead，though other hydrocarbons from oil can also be used．Ammonia plants always include hydrogen producing plants linked directly to the production of ammonia.
原料。该过程需要以下几种原料（进料）的能源、N2 和H2。N2 很容易从空气中提取，但是H2 的来源很成问题。以前，H2 来源于通过煤的焦化反应，煤用作蒸汽重整的原料（主要是C 的来源），在蒸汽重整过程中，水蒸气与C 反应生成H2、CO 和CO2。如今，以天然气（主要是甲烷）代替，如今，以天然气（主要是甲烷）代替，尽管也使用来自石油的烃类物质。通常，制NH3 的工厂包括与NH3 生产相连接的H2 生产车间。
Prior to reforming reactions，sulphur-containing compounds must be removed from the hydrocarbon feedstock as they poison both the reforming catalysts and the Haber catalysts．The first desulphurisation stage involves a cobalt-molybdenum catalyst, which hydrogenates all sulphur -containing compounds to hydrogen sulfide．This can then be removed by reaction with zinc oxide (to give zinc sulfide and water)．
在重整反应之前，含硫化合物必须从烃原料中除去，因为它们既能污染重整催化剂又能污染Harber催化剂。第一除硫步骤需要钴-铜催化剂。该催化剂能将所有的含硫化合物氢化生成H2S，H2S 能与ZnO反应（ZnS 和H2O）加以除去。
The major reforming reactions are typified by the following reactions of methane (which occur over nickel-based catalysts at about 750~C)：
主要的重整反应中，下列甲烷反应最为典型（甲烷的反应发生于约7500C.含镍催化剂上） Other hydrocarbons undergo similar reactions 其他烃经历类似反应。
In the secondary reformers, ir is injected into the gas stream at about 1 100~C. In addition to me other reactions occurring, the oxygen in the air reacts with hydrogen to give water, leaving a mixture with close to the ideal 3:1 ratio of hydrogen to nitrogen with no contaminating oxygen. Further reactions, however, are necessary to convert more of the carbon monoxide into hydrogen and carbon dioxide via the shift reaction.
在次级重整器中，空气注入温度11000C 的气流，除了发生其他反应外，空气中的O2 与H2 反应生成H2O，结果剩下不会污染的O2 的混合物，该混合物中O2 与H2 的比接近理想比3：1.然而，下一步反应必须通过下列转化反应将更多的CO 转变为H2 和CO2 。
This reaction is carried out at lower temperatures and in two stages(400~C with an iron catalyst and 220℃with a copper catalyst)to ensure that conversion is as complete as possible．
为使其尽可能完全的转化，此反应应该在较低温度下以两步进行（一步是在4000C 用铁为催化剂，另一步是在2000C 下用催化剂）。
In the next stage, carbon dioxide must be removed from the gas mixture, and this is accomplished by reacting the acidic gas with an alkaline solution such as potassium hydroxide and/or mono, or di-ethanolamine． 下一步中，CO2 必须从气体混合物中除去。除去CO2 可以用该酸性气体与碱性溶液（如KOH 和（或）单乙醇胺或二乙醇胺反应得以实现。
By this stage there is still too much contamination of the hydrogen—nitrogen mixture by carbon monoxide(which poisons the Haber catalysts), and another step is needed to get the amount of CO down to ppm levels. This step is called methanation and involves the reaction of CO and hydrogen to give methane(i.e.the reverse of some of the reforming steps)．The reaction operates at about 325℃and uses a nickel catalyst．
这一步中，任然存在CO（污染Harbor 催化剂）对H2-N2 混合物造成很大污染，需要用另一步去将CO 得量降低至PPM 级，这一步称为甲烷化反应，涉及到CO 和H2 反应生成甲烷（即一些重整反应的逆反应），该反应大约在325℃操作，用一种Ni 催化剂。
Now the synthesis gas mixture is ready to go into a Haber reaction．合成气混合物准备用于Harbor 反应
Ammonia production. The common features of a11 the different varieties of ammonia plant are that the synthesis gas mixture is heated，compressed and passed into a reactor containing a catalyst．The essential equation for the reaction is simple：
NH3 的生产各种不同氨厂的共同特征是合成经过加热，压缩，递往含成催化剂的反应器中，该基本反应方程式很简单：
What industry needs to achieve in the process is an acceptable combination of reaction speed and reaction yield．Different compromises have been sought at different times and in different economic circumstances．Early plants plumped for very high pressure (to… reactor)．but many of the most modem plants have accepted much lower one-pass yields at lower pressures and have also opted for lower temperatures to conserve energy．In order to ensure the maximum yield in the reactor the synthesis gas is usually cooled as it reaches equilibrium. This can be done by the use of heat exchangers or by the injection of cool gas into the reactors at an appropriate point．The effect of this is to freeze the reaction as near to equilibrium as possible. Since the reaction is exothermic (and… temperatures) the heat must be carefully controlled in this way to achieve good yields.该工业要实现的事：反应速度和反应产率的结合要令人满意， 不同的时期和不同的经济环境下谋求不同的折中方案，早期的制