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1、Specialized English for chemistryChemical Enineering and TechnologyLesson 3 Catalysts for Industrial ProcessesThe criteria for an industrially successful catalyst are very stringent.Criteria （批评、判断等的）标准，准则（批评、判断等的）标准，准则(criterion的名词的名词复数复数 Stringent adj.严格的严格的;迫切的迫切的;（货币）紧缩的（货币）紧缩的The two most impor
2、tant considerations are activity and durability;suitability for basic study is not a factor,and this has retarded progress in our understanding of how such technical catalysts really operate.Let us consider the two prime requirements.prime adj.最好的最好的;首要的首要的;最初的最初的;基本的基本的 n.精华精华;初期初期;全盛时期全盛时期;青年青年 vt
3、.使准备好使准备好;填装填装;事先指导事先指导First,the catalyst must be able to effect the desired reaction at an acceptable rate under conditions of temperature and pressure that are practicable.Chemical technology has advanced to the point where temperatures as high as 1600K and pressure up to 350 atm(35MPa)present no
4、difficulties and thermodynamic considerations sometimes necessitate their use to attain reasonable equilibrium yields of products.Necessitate vt.使使成为必要，需要成为必要，需要;强迫，迫强迫，迫使使equilibrium n.平衡，均势平衡，均势;平静平静If however good yields can be obtained at low temperatures and pressures,then there is every incent
5、ive to find a catalyst that will operate under the mildest possible conditions,since the use of extreme conditions is very costly.Incentive n.动机动机;刺激刺激;诱因诱因;鼓励鼓励 adj.刺激性的刺激性的;鼓励性鼓励性质的质的Mildest 适当的适当的 适中的适中的It is concurrently important that side-reactions are minimal,especially those leading to poiso
6、ning or deactivation through carbon deposition.Second,the catalyst must be able to sustain the desired reaction over prolonged periods:in some processes,a catalyst life of several years is not uncommon,and is economically necessary.Prolong vt.延长，拉长延长，拉长;拖延，延期拖延，延期Clearly the longer it lasts,the smal
7、ler the contribution that its initial cost makes to the overall cost of the process will be.initial adj.最初的最初的;开始的开始的;首字母的首字母的Initial cost is rarely of over-riding importance:it is usually cheaper in the long run to use an expensive catalyst that will last a long time than a cheap one that has to be
8、 replaced frequently.The chief causes of deterioration in use are:reversible poisoning due to impurities in the reactants or to side-reactions,and irreversible physical changes including loss of surface area(sintering)or mechanical failure.Deterioration n.恶化恶化;变坏变坏;退化退化;堕落堕落Irreversible adj.不可逆的不可逆的
9、;不能翻转的不能翻转的;不能倒置的不能倒置的sintering n.泉华，烧结物，熔渣泉华，烧结物，熔渣 vt.使烧结使烧结Reversible poisoning may with luck be rectified by simple treatment,such as oxidation or washing,without removing the catalyst from the reactor.Rectified adj.医医矫正的，调整的矫正的，调整的 v.改正，矫正改正，矫正(rectify的过去式和过去分词的过去式和过去分词);精精馏馏To guard against ph
10、ysical changes,careful attention has to be given to the strength of the catalyst.guard n.警卫警卫;狱吏，看守狱吏，看守;护卫队护卫队;防护装置防护装置 vt.保卫，守护保卫，守护;看守看守;加防护装置加防护装置;谨慎使用谨慎使用 vi.警惕警惕;警卫警卫The preferred physical form for a catalyst is determined entirely by the manner in which it is to be used.Its particle size is e
11、specially fixed,at least within broad limits,by the type of reactor to be employed.A rough criterion is whether or not one can distinguish separate particles with the naked eye.Criterion n.（批评、判断等的）标准，准则（批评、判断等的）标准，准则;规范规范When the reactants are solely gases or vapors,there are only two possible basi
12、c types of reactor that can be used.solely adv.唯一地唯一地;仅仅仅仅;独一无二地独一无二地;纯粹纯粹When the reactants are solely gases or vapors,there are only two possible basic types of reactor that can be used.solely adv.唯一地唯一地;仅仅仅仅;独一无二地独一无二地;纯粹纯粹Fixed-bed reactorFluidized-bed reactorTubular reactorkettle reactorPacked
13、tower reactorTower reactorA fixed-bed reactor is one in which a tube is packed with“coarse”catalyst particles through which the reactants flow.Coarse adj.粗鄙的粗鄙的;粗糙的粗糙的;粗野的粗野的;粗制滥造的粗制滥造的As a result of the obstruction to gas flow by the particles,a pressure drop occurs across the bed,and a positive pr
14、essure has to be applied at the inlet to secure an adequate flow-rate.The size of the pressure drop incrases with increasing flow-rate and bed length,and with decreasing particle size.Many different shapes and sizes of catalyst particles are used in fixed-bed reactors,and a great deal of skill and e
15、xperience goes into choosing the most appropriate for a given set of conditions.appropriate adj.适当的适当的;恰当的恰当的;合适的合适的 v.盗用盗用;侵吞侵吞;拨（专款等）拨（专款等）Spherical TrifoliumCylindricalSaddleDimensions of more common forms are usually between 2mm and 2cm.Dimensions vi.按规格尺寸切割按规格尺寸切割 vt.在在上标尺寸上标尺寸 n.面积面积;特点特点;（长、宽
16、、厚、高等的）尺寸（长、宽、厚、高等的）尺寸;重要性重要性;尺寸尺寸(dimension的的.When,as in the case of ammonia oxidation,it is desired to use a pure metal catalyst at high temperature and a very short time.Ammonia n.氨氨;氨水氨水;氨气氨气So a bed of 20 to 30 finely woven metal gauges is used,this is another catalyst form suited for use in a
17、fixed-bed reactor.Woven v.编，织，织成编，织，织成(weave的过去分词的过去分词);编排编排;杜杜撰撰;（把（把）编成）编成gauges n.测量的标准或范围测量的标准或范围;尺度，标准尺度，标准;测量仪器测量仪器;评估评估 vt.（用仪器）测量（用仪器）测量;确定容量，体积或内容确定容量，体积或内容;评估，评估，判断判断;采用采用Since many catalyzed reactions are strongly exothermic,fixed-bed reactors must contain a facility for removing the unwa
18、nted enthalpy of reaction.exothermic adj.发热的，放出热量的发热的，放出热量的Enthalpy n.热热焓焓;物物热函热函;热含量热含量 HJacketSnake tubeTubular heat exchangerThis may be done in one or two ways.A multi tubular reactor contains a large number of reaction tubes,typically 2.5 cm in diameter,with a cooling gas or liquid flowing betw
19、een them.tubular adj.管系组织的管系组织的;管管子形的，管状的子形的，管状的;管子做成的管子做成的;发吹管发吹管般声音的般声音的Alternatively the bed may be split into sections,with provision for cooling the gas in the spaces between.Alternatively adv.二者择一地二者择一地;要不然要不然;或者或者Intermediate indirect heat transferQuenching with feed gasA further important an
20、d quite different catalyst form is finding application,especially in air-pollution control.This is the so-called monolithic structure,which consists of a block of ceramic material(-alumina or mullite),through which runs fine parallel channels.monolithic adj.独块巨石的独块巨石的;整体的整体的;庞大的庞大的 Ceramic dj.陶器的，与陶
21、器有关的陶器的，与陶器有关的;陶瓷的，陶制的陶瓷的，陶制的;制陶的制陶的 n.陶瓷制品陶瓷制品;陶瓷器陶瓷器;制陶艺术制陶艺术;陶瓷装潢艺术陶瓷装潢艺术alumina n.氧化铝，矾土氧化铝，矾土;铝土铝土 Mullite n.多铝红柱石多铝红柱石;莫来石莫来石parallel adj.平行的平行的;相同的，类似的相同的，类似的;电电并联的并联的;计计并行的并行的The structures can be made in many different ways,each of which results in a characteristic channel shape.The blocks
22、are obtainable in a range of shapes and sizes,and a single block when inserted in a container therefore behaves as a fixed-bed reactor.Because of the low porosity of the material from which these structure are made,it is usually necessary to attach a thin layer of a more porous substance to which th
23、e catalytically active phase can adhere.porosity n.多孔性，有孔性多孔性，有孔性Adhere vi.黏附黏附;附着附着;坚持坚持;追随追随 vt.使粘附使粘附;遵循，坚遵循，坚持持;追随，依附追随，依附Such monolithic structures have several clear advantages over pellets or granules packed loosely in a tube.Monolithic adj.独块巨石的独块巨石的;整体的整体的;庞大的庞大的Pellets n.小球小球;小子弹小子弹;石弹，炮弹石
24、弹，炮弹;（货币等的）（货币等的）圆浮雕圆浮雕 v.用小球扔用小球扔;用子弹射击用子弹射击;将将制成丸状制成丸状;把把弄成小球形弄成小球形granules n.小颗粒，小硬粒小颗粒，小硬粒(granule的名词复数的名词复数)First,the pressure drop through the bed is less for equal quantities of catalyst,thus permitting higher space velocities to be achieved;Velocities n.速度速度(velocity的名词复数的名词复数);高速，快高速，快速速sec
25、ondly,there is no attrition of the catalyst due to particles rubbing against each other and forming fine dust.Attrition n.消耗消耗;消磨消磨;摩擦摩擦;（神学）不彻底的忏悔（神学）不彻底的忏悔Rubbing n.拓本，拓印拓本，拓印fine dust 细粉尘细粉尘;纤尘纤尘Their ability to withstand thermal shock is however in some cases limited.Withstand vt.经受，承受，禁得起经受，承受，
26、禁得起;反抗反抗 vi.反抗反抗;耐得住，禁得起耐得住，禁得起The second basic kind of reactor for gaseous reactions is the fluidized bed.Gaseous adj.气态的，气态的，似气体的似气体的;无实质的无实质的;美俚美俚不可靠的不可靠的;气性气性Here the catalyst consists of fine particles.And when the gas flow upwards through a bed,such powder attaining a critical velocity the bed
27、 appears to“boil”:it expands significantly,and the particles are in continuous motion.Critical adj.批评的，爱挑剔的批评的，爱挑剔的;关键的关键的;严重的严重的;极重要的极重要的Velocity n.速率，速度速率，速度;周转率周转率;高速，快速高速，快速In this state the bed is said to be fluidized.Fluidized adj.流态化的，沸腾的流态化的，沸腾的 v.使液化，流（态）化使液化，流（态）化(fluidize的过去式和过去分的过去式和过去分词
28、词)The behavior gives certain advantages over fixed beds,for example,heat transfer characteriatics are much better,and the pressure drop increases far less quickly with increasing flow-rate.ExercisesVocabulary1 Cataysts are substances which by their mere presence evoke chemical reaction.A change B im
29、pede C fortify D cause2 The essence of catalysts is not the entering but the falling out.A reaction B consumption C departure D appearance3 In practice this definition proves too restrictive.A board B activated C vague D specific4 A catalyst is generally not used up itself in a chemical reaction.A r
30、equired B activated C consumed D energetic5 The activation energy barrier must be surmounted for reaction to take place.A conquered B permitted C removed D determined6 Catalysts that accelerate hydrolysis of esters must also accelerate esterification of alchols.A proceed B develop C fasten D chain7
31、A distinction is made between homogeneous catalysts and heterogeneous catalysis.A comparison B difference C decision D proportion8 A new reaction mechanism permits the reaction to occur via a different activated complex.A through B within C beyond D outsideFill in the blanks with the following phras
32、es.use up,be referred to as,fall out,in practice,in terms of,be provided with,make a distinction between1 The leader of the team was glad to find that not a single man()in the long march.2 Your idea seems quite appealing,but it wont work().3 The incident which took place during the weekend()politica
33、l.4 The teacher asked the student to explain the sentence()grammar.5 The student in this school()food and books.6 To his surprise,all his money had been()before the end of his journey.7 The professor asked the student to()American English and British English.翻译1 The process of increasing the rate of
34、 a reaction through the use of a catalyst which is not used up itself in the reaction is referred to as catalysis.2 The essence of catalysts is not the entering but the falling out.3 A catalyst is a substance that changes the velocity of a chemical reaction without itself appearing in the end products.4 This usually means that the reaction mixture is liquid or gaseous and the catalyst solid.