Catalyst Manufacture, Second Edition,. Alvin B. This work provides a practical, step-by-step guide to the preparation, production and operation of all commercially used catalysts, taking into account general safety considerations and up-to-date regulations from the Occupational Health Administration and the Environmental Protection Agency. This second edition contains updated and expanded material on the regeneration, reactivity and recovery of used catalysts; problems related to environmental catalysis; a unique CO oxidation catalyst; and more. Catalysts Prepared by Precipitation.
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Manufacturing Engineering Practices in Metal Fabrication Industries in GhanaVIDEO ON THE TOPIC: What is a catalyst and how does catalysis work?
Catalysts are substances that speed up reactions by providing an alternative pathway for the breaking and making of bonds. Key to this alternative pathway is a lower activation energy than that required for the uncatalysed reaction.
Catalysts are often specific for one particular reaction and this is particularly so for enzymes which catalyse biological reactions, for example in the fermentation of carbohydrates to produce biofuels. Much fundamental and applied research is done by industrial companies and university research laboratories to find out how catalysts work and to improve their effectiveness.
Further, it may be possible to reduce the amount of reactants that are wasted forming unwanted by-products. If the catalyst is in the same phase as the reactants, it is referred to as a homogeneous catalyst. A heterogeneous catalyst on the other hand is in a different phase to the reactants and products, and is often favoured in industry, being easily separated from the products, although it is often less specific and allows side reactions to occur.
The most common examples of heterogeneous catalysis in industry involve the reactions of gases being passed over the surface of a solid, often a metal, a metal oxide or a zeolite Table 1.
Table 1 Examples of industrial processes using heterogeneous catalysis. The gas molecules interact with atoms or ions on the surface of the solid. The first process usually involves the formation of very weak intermolecular bonds, a process known as physisorption, followed by chemical bonds being formed, a process known as chemisorption. Physisorption can be likened to a physical process such as liquefaction.
Indeed the enthalpy changes that occur in physisorption are ca to kJ mol -1 , similar to those of enthalpy changes when a gas condenses to form a liquid. The enthalpies of chemisorption are similar to the values found for enthalpies of reaction. They have a very wide range, just like the range for non-catalytic chemical reactions.
An example of the stepwise processes that occur in heterogeneous catalysis is the oxidation of carbon monoxide to carbon dioxide over palladium. This is a very important process in everyday life. Motor vehicles are fitted with catalytic converters. These consist of a metal casing in which there are two metals, palladium and rhodium, dispersed very finely on the surface of a ceramic support that resembles a honeycomb of holes.
The converter is placed between the engine and the outlet of the exhaust pipe. The exhaust gases contain carbon monoxide and unburned hydrocarbons that react with the excess oxygen to form carbon dioxide and water vapour, the reaction being catalysed principally by the palladium:.
The exhaust gases also contain nitrogen II oxide nitric oxide, NO , and this is removed by reactions catalysed principally by the rhodium:. The accepted mechanism for the oxidation of carbon monoxide to carbon dioxide involves the chemisorption of both carbon monoxide molecules and oxygen molecules on the surface of the metals.
The adsorbed oxygen molecules dissociate into separate atoms of oxygen. Each of these oxygen atoms can combine with a chemisorbed carbon monoxide molecule to form a carbon dioxide molecule.
The carbon dioxide molecules are then desorbed from the surface of the catalyst. A representation of these steps is shown in Figure 1. Figure 1 A mechanism for the oxidation of carbon monoxide. Each of these steps has a much lower activation energy than the homogeneous reaction between the carbon monoxide and oxygen. The removal of carbon monoxide, unburned hydrocarbons and nitrogen II oxide from car and lorry exhausts is very important for this mixture leads to photochemical smogs which aggravate respiratory diseases such as asthma.
Platinum, palladium and rhodium are all used but are very expensive metals and indeed each is more expensive than gold. Recently, much work has been devoted to making catalysts with very tiny particles of the metals, an example of the advances being made by nanotechnology. It is not simply the ability of the heterogeneous catalyst's surface to interact with the reactant molecules, chemisorption, that makes it a good catalyst.
If the adsorption is too exothermic, i. The enthalpy of chemisorption has to be sufficiently exothermic for chemisorption to take place, but not so high that it does not allow further reaction to proceed. For example, in the oxidation of carbon monoxide, molybdenum might at first sight be favoured as a choice, as oxygen is readily chemisorbed by the metal.
However, the resulting oxygen atoms do not react further as they are too strongly adsorbed on the surface. Platinum and palladium, on the other hand, have lower enthalpies of chemisorption with oxygen, and the oxygen atoms can then react further with adsorbed carbon monoxide.
Another point to consider in choosing a catalyst is that the product must not be able to adsorb too strongly to its surface. Carbon dioxide does not adsorb strongly on platinum and palladium and so it is rapidly desorbed into the gas phase. A testimony to the importance of catalysis today is the award of the Nobel Prize in Chemistry in to Gerhard Ertl for his work in elucidating, amongst other processes, the mechanism for the synthesis of ammonia the Haber Process :.
Ertl obtained crucial evidence on how iron catalyses the dissociation of the nitrogen molecules and hydrogen molecules leading to the formation of ammonia Figure 2 :. Figure 2 A mechanism for the catalytic synthesis of ammonia.
Figure 3 shows how the activation energy barriers are much lower than the estimated activation energy barrier which would be at least kJ mol1 for the uncatalysed synthesis of ammonia. Figure 3 The activation energy barriers for the reactions occurring during the catalytic synthesis of ammonia. To be successful the catalyst must allow the reaction to proceed at a suitable rate under conditions that are economically desirable, at as low a temperature and pressure as possible.
It must also be long lasting. Some reactions lead to undesirable side products. For example in the cracking of gas oil , carbon is formed which is deposited on the surface of the catalyst, a zeolite, and leads to a rapid deterioration of its effectiveness. Many catalysts are prone to poisoning which occurs when an impurity attaches itself to the surface of the catalyst and prevents adsorption of the reactants. Minute traces of such a substance can ruin the process, One example is sulfur dioxide, which poisons the surface of platinum and palladium.
Thus all traces of sulfur compounds must be removed from the petrol used in cars fitted with catalytic converters. Further, solid catalysts are much more effective if they are finely divided as this increases the surface area.
Figures 4 and 5 Two ways by which the surface area of a catalyst can be increased. At high temperatures, the particles of a finely divided catalyst tend to fuse together and the powder may 'cake', a process known as sintering. This reduces the activity of the catalyst and steps must be taken to avoid this. One way is to add another substance, known as a promoter.
When iron is used as the catalyst in the Haber Process, aluminium oxide is added and acts as a barrier to the fusion of the metal particles. A second promoter is added, potassium oxide, that appears to cause the nitrogen atoms to be chemisorbed more readily, thus accelerating the slowest step in the reaction scheme.
One of the most important reactions in which aluminium oxide , Al 2 O 3 , often referred to as alumina takes part in an industrial reaction is in platforming , in which naphtha is reformed over aluminina impregnated with platinum or rhenium.
Both the oxide and the metals have catalytic roles to play, an example of bifunctional catalysis. There are hydroxyl groups on the surface of alumina which are, in effect, sites which are negatively charged to which a hydrogen ion is attached that can act as an acid catalyst.
Silicon dioxide silica is another acidic oxide used in industry. It becomes particularly active if it has been coated with an acid such as phosphoric acid , thereby increasing the number of active acidic sites.
For example, the manufacture of ethanol is achieved by the hydration of ethene using silica, coated with phosphoric acid:. Figure 7 A mechanism for the hydration of ethene to ethanol. Aluminosilicates are also used as catalysts when an acid site is required.
These are made from silicon dioxide silica and aluminium oxide. They contain silicate ions, SiO 4 4- that have a tetrahedral structure which can be linked together in several ways. When some of the Si atoms are replaced with Al atoms, the result is an aluminosilicate. Hydrogen ions are again associated with the aluminium atoms:. A particular class of aluminosilicates that has excited huge interest in recent years is the zeolites. There are many different zeolites because of the different ways in which the atoms can be arranged.
Their structure of silicate and aluminate ions can have large vacant spaces in three dimensional structures that give room for cations such as sodium and calcium and molecules such as water. The spaces are interconnected and form long channels and pores which are of different sizes in different zeolites. Figure 8 The structure of a zeolite example figure.
A zeolite which is commonly used in many catalytic reactions is ZSM-5 which is prepared from sodium aluminate a solution of aluminium oxide in aqueous sodium hydroxide and a colloidal solution of silica, sodium hydroxide, sulfuric acid and tetrapropylammonium bromide. It is, for example, a very effective catalyst for the conversion of methylbenzene toluene to the three dimethylbenzenes xylenes. However, if the zeolite is washed with phosphoric acid and heated strongly, minute particles of phosphorus V oxide are deposited on the surface making the pores slightly smaller.
This restricts the diffusion of the 1,2- and 1,3-isomers and they are held in the pores until they are converted into the 1,4-isomer and can escape Figure 9. The ability of the zeolite to adsorb some molecules and to reject others gives it the ability to act as a molecular sieve.
Further purification of ethanol requires the use of a zeolite which absorbs the water preferentially. Table 2 gives examples of industrial processes involving zeolites. Table 2 Examples of industrial processes using zeolites. Bifunctional catalysts are able, as the name implies, to catalyse the conversion of one compound to another, using two substances on the surface. For example, in reforming naphtha a mixture of straight chain alkanes, with carbon atoms a bifunctional catalyst is used.
The most well known one is platinum impregnated on the surface of alumina and both the metal and the oxide play their parts in the process. As can be seen Figure 10 , the first step is the dehydrogenation of the alkanes to alkenes, catalysed by the metal, followed eventually by adsorption of the alkene molecules on alumina.
Because platinum is involved, the reforming is sometimes called platforming. The hydrogen ensures that the resulting alkenes and cycloalkenes subsequently react with hydrogen to form saturated compounds.
Figure 10 A mechanism for the reforming of butane to 2-methylpropene isobutene. The branched alkene molecule is desorbed into the gas phase until it is readsorbed on to a metal site where it is hydrogenated to form a branched alkane, 2-methylpropane isobutane , which is then desorbed into the gas phase.
In the industrial process, naphtha vapour is passed over platinum and rhenium ca 0. The rhenium is thought to play an interesting role. If a sulfur compound is allowed to pass over the surface of the catalyst, it is preferentially adsorbed by the rhenium. If sulfur compounds are not removed, reactions occur leading eventually to the formation of carbon which causes the activity of the catalyst to be markedly reduced.
Branched alkanes have a much higher octane rating than straight chain ones. Not only are the alkanes now branched, but cycloalkanes are also formed and, from them, aromatic hydrocarbons. All three classes of hydrocarbon have a higher octane rating than naphtha.
These products have brought improved performance to numerous refineries around the world. That work continues today using smart feed characterization, plus our extensive laboratory, pilot-plant and commercial performance evaluations. These analyses and performance evaluations are conducted through close coordination between our customers and our highly trained technical specialists. Modern FCC units process a variety of feedstocks.
We offer various catalyst manufacturing technologies as well as zeolite synthesis technologies to support your custom catalyst project. We can also prepare lab-scale catalyst samples at your request. Extrusion, granulation and tablet compression technologies are available for catalyst and catalyst support manufacturing. English Japanese Chinese. Catalyst Preparation, Commercialization and Toll Manufacturing.
Catalysis in industry
Umicore is the first company in the world to have introduced a Sustainable Procurement Framework for Cobalt and is the first to obtain external validation for its ethical procurement approach in this area. It aims to minimize the risk of any connection between the cobalt in its supply chain — and subsequently that of its customers — and human rights abuses or unethical business practices. Umicore is leading the way in clean mobility. Their innovative vehicles spread the message that sustainable mobility can be a reality.SEE VIDEO BY TOPIC: CTPL Automation- Catalyst Substrate coating automation
AbstractThe purpose of this paper is to assess the manufacturing engineering practices in metal fabrication industries in Ghana. In the study, the various manufacturing practices were investigated using a questionnaire administered on metal manufacturers in the country. In addition, some amount of data was generated through personal observation and informal discussions. The survey revealed that most of the metal manufacturers in the country have low technical levels of training and computer skills and as such have not been able to integrate computer and other high-tech automatic systems in their manufacturing activities. It further revealed that, critical state of the art manufacturing engineering tools such as: concurrent engineering CE , quality function deployment QFD , continuous process improvements techniques, process scheduling, technical drawing etcetera, are hardly utilized by the metal manufacturers in their metal products design and manufacturing activities. To enhance manufacturing engineering activities in the country, relevant curricula on the training of engineers and technicians in all disciplines of manufacturing engineering must be initiated in technical institutions. The Ghana Institution of Engineers, the Ghana Standards Board as well as the universities and the polytechnics should organize in-service training for the manufacturers to enable them update and upgrade their technical competencies in the usage of the critical manufacturing engineering tools. Metal fabrication industries in Ghana can be designated as Micro, Small, Medium and Large industries. These designations are based on staff strength.
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Catalysis pp Cite as. Products produced by catalytic oxidation technology using dioxygen as oxidant are utilized extensively by modern society in many diverse applications. The present chapter outlines the history of this oxidation technology, indicating that in the cases of many products, earlier routes which did not involve direct oxidation, have been replaced by lower-cost oxidation routes. The importance of catalyst selectivity is emphasised and the way in which developments of both major and evolutionary kinds have occurred is illustrated by detailed discussion of the three products, sulfuric acid, nitric acid and maleic anhydride.
What sets us apart from some other licensors and consultants is the knowledge we have gained from our corporate heritage as the owner and operator of large, complex industrial process plants. Our technologies and business solutions reflect our many years of experience in designing, building and operating such facilities. We have a range of catalysts with a specific focus on hydroprocessing, oxidation, renewable fuel, and environmental catalysts and systems. Improve refinery performance, operations, catalyst utilisation, and more by leveraging our team and refinery services. Leveraging our owner-operator experience, our oil and gas process experts can apply innovative licensed technologies to meet our customers' objectives. The joint venture will provide a long-term sustainable solution for catalyst reclamation and recycling. Catalysts We have a range of catalysts with a specific focus on hydroprocessing, oxidation, renewable fuel, and environmental catalysts and systems. Services Improve refinery performance, operations, catalyst utilisation, and more by leveraging our team and refinery services. Who We Are Leveraging our owner-operator experience, our oil and gas process experts can apply innovative licensed technologies to meet our customers' objectives.
The Historical Development of Catalytic Oxidation Processes
The first time a catalyst was used in the industry was in by J. Hughes in the manufacture of lead chamber sulfuric acid. Since then catalysts have been in use in a large portion of the chemical industry. In the start only pure components were used as catalysts, but after the year multicomponent catalysts were studied and are now commonly used in the industry. In the chemical industry and industrial research, catalysis play an important role. Different catalysts are in constant development to fulfil economic, political and environmental demands. When using a catalyst, it is possible to replace a polluting chemical reaction with a more environmentally friendly alternative. Today, and in the future, this can be vital for the chemical industry. For a company, a new and improved catalyst can be a huge advantage for a competitive manufacturing cost. To achieve the best understanding and development of a catalyst it is important that different special fields work together.
Catalysts Europe represents the leading catalyst manufacturers in Europe. Catalysts are substances including solid, liquid and gases that increases the rate of a chemical reactions which are vital to the chemical industry. They allow the efficient production of many chemicals and are used in a vast range of industrial applications including fine chemicals, refinery operations, edible oils, pharmaceuticals and polymers. Specific applications include the reduction of environmental emissions and the production of low sulphur fuels. Europe is a leader in catalyst technology. Promote the safe use of catalysts over the whole life cycle including manufacture, installation and removal and spent catalyst management as well as highlighting the importance of catalysts in everyday life.
While this may sound like science fiction, these kinds of factories have been a reality for more than 15 years. To imagine a world where robots do all the physical work, one simply needs to look at the most ambitious and technology-laden factories of today. In June , the Chinese e-commerce giant JD.
Chemicals are as important for catalyzing other chemicals as they are for producing end-products. Noah Technologies works with manufacturers all over the world to supply ultra high-purity chemicals for catalytic reactions.
Developing and proving innovative manufacturing processes and technologies in an agile, low risk environment, in partnership with industry, academia and other institutions. We focus on delivering bespoke manufacturing system solutions for our customers. We specialise in digital manufacturing , additive manufacturing , automation and robotics as well as intelligent automation. This creates a high quality environment for the development and demonstration of new processes and technologies on an industrial scale.
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