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New method to produce HDS catalyst

Summary

Researchers at CIMAV in Mexico have investigated the effectiveness of Ni-Mo-W catalysts synthesised by mechanical alloying for hydrodesulphurisation of dibenzothiophene. The catalysts showed a moderate catalytic activity, due to the synergised effect of small particle and crystal size and the presence of porosity.

Abstract

As a result of new environmental regulations to reduce the amount of sulphur in vehicle transportation fuels, the need to study the catalytic hydrodesulphurisation process is steadily increasing1,2. Therefore, great interest has been focused on the research of new routes to obtain catalysts for hydrodesulphurisation (HDS). In spite of the great variety of routes used, mechanical alloying (MA) routes have not been explored satisfactorily. By using mechanical alloying it has been possible to synthesise novel materials with special physical and chemical properties3,4. Elaboration of Raney-type catalyst combines powder metallurgy routes with chemical treatments to obtain a highly porous final product.

Unsupported catalysts called NEBULA (New Bulk Activity) based on Ni-Mo-W, are four times more active than typical catalysts and two times more than advanced formulations5. These types of catalysts opened the way to new bulk catalysts with improved catalytic activity in HDS.

In this work, quaternary alloys of Ni-Mo-W-Al were prepared by mechanical alloying. In addition, a process of chemical extraction by alkaline leaching was applied to remove aluminum in order to increase the specific surface area (SSA) and to generate porous materials, which were tested in the HDS of dibenzothiophene (DBT) to determine their catalytic activity and the selectivity.

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Dow's new mercaptan removal solvent

Summary

Amine solvents have been used for decades for removal of H2S and CO2 from a variety of gas streams, but have proven less effective for mercaptan removal. S. A. Bedell, M. Miller, J. Griffin and C. Schubert of The Dow Chemical Company present a new concept for increasing mercaptan solubility in aqueous amines solutions – Dow MRA.

Abstract

Since mercaptans are much weaker acids than H2S or CO2, they react to only a small degree with amines, which is why stronger bases like caustic solutions are often needed for effective mercaptan removal. The downside of caustic scrubbing is the lack of regenerability that requires the use of catalysed autoxidation of the mercaptan to disulphides. Fig. 1 shows the behaviour of a commonly used amine solution (50 % MDEA) toward mercaptan solubility1 as the solution loading increases. The solutions were loaded by neutralisation with a strong acid (this laboratory technique will be discussed in more detail in a future paper). As loading is increased and pH drops, there is a sharp decrease in mercaptan solubility. The use of very lean loadings and high circulation rates can often help mercaptan removal in an amine scrubber, but most mercaptan removal rates are limited by the low degree of reaction with the amine.

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Sulphuric acid in the rayon industry

Summary

The sulphuric acid plant at Indo Bharat Rayon is an integral part of the production process for viscose staple fibre. A.P. Goel of Poseidon Engineering and C.K. Dutta of Indo Bharat Rayon, discuss the key design features of the new sulphuric acid plant recently completed as part of an expansion of viscose fibre production.

Abstract

Rayon is the oldest commercial manmade fibre. P.T. Indo Bharat Rayon (IBR), located in West Java, Indonesia, is part of the Aditya Birla Group of India and is one of the leading viscose rayon producers in the world. IBR has taken giant strides from a modest capacity of 45 t/d viscose staple fibre (VSF) in 1982 to its present capacity of 425 t/d, almost a tenfold increase in less than 25 years. The annual growth in viscose staple fibre production at Indo Bharat Rayon is shown in Fig. 1.

Sulphuric acid is one of the basic raw materials for VSF manufacturing. Specific consumption of sulphuric acid is 0.75-0.8 tonne/tonne of fibre. The sulphuric acid plant is normally an integral part of rayon production, mainly due to significant economies from energy integration with the fibre plant, e.g. utilisation of steam and water generated in the acid plant, re-circulation of soft water for acid cooling and utilisation of 70 % acid from the main plant. Complete heat from the acid plant is utilised, and this perhaps is one of the few instances where energy recovery is 98 %+ of that potentially available and utilisable.

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Recent trends in the sulphur and sulphuric acid markets

Summary

As an introduction to our statistical supplement, Mike Kitto of the British Sulphur Consultants division of CRU highlights key developments and trends in global production, consumption and trade of sulphur-in-all-forms.

Abstract

World production of sulphur-in-all-forms (SAF) is estimated to have totalled 72.1 million tonnes S/S-equivalent in 2005, up from 70.0 million tonnes in 2004. Brimstone production rose by 1.3 million tonnes to 48.0 million tonnes and output of sulphur-in-other-forms (SOF) increased by 0.8 million tonnes S-equivalent to 18.5 million tonnes, but pyrites production declined by 0.1 million tonnes S to 5.6 million tonnes, despite a further increase in Chinese output.

Brimstone production would undoubtedly have been higher but for the fact that the operation of many oil refineries on the US Gulf Coast was seriously disrupted by Hurri­canes Katrina and Rita that swept through the region in August and September 2005. By the end of the year, most of the affected plants were back in operation, some at reduced operating rates, but BP’s large Texas City refinery remained closed for most of the first quarter of 2006. Sulphur recovery at US oil refineries fell to 6.8 million tonnes in 2005, 0.5 million tonnes below the 2004 level. There was also a decline in sulphur production at the oil sands plants in northern Alberta, Canada, in 2005 as a result of fire damage sustained at Sun­cor’s plant early in the year.

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Full steam ahead

Summary

Modern sulphuric acid plants are, in fact, generating stations for electric power. The superheated, high-pressure steam produced in the waste heat recovery system must, therefore, be maximised and its temperature and pressure maintained at optimum values. Dr V.V. Rao of Chemithon Engineers Pvt, Mumbai, discusses how this should be achieved while operating the sulphuric acid plant efficiently with high conversion efficiency and high heat recovery.

Abstract

Sulphuric acid plants based on sulphur burning generate steam as a byproduct. Heat is evolved during sulphur combustion, oxidation of SO2 to SO3 in the catalyst beds, formation of H2SO4 from SO3 and H2O in absorption towers, compression of air and cooling of hot gases prior to absorption. Heat is also released in sulphuric acid plants based on metallurgical gases during SO2 oxidation and it can be recovered to generate steam. As the capacity of sulphur based and metallurgical gas based plants are increasing and power costs have been rising in recent times, the generation of superheated steam in sulphuric acid plants and its use for electric power generation have gained tremendous importance. It is interesting to note that power is generated without CO2 emissions and therefore, sulphuric acid plants can claim carbon credits.

A modern sulphuric acid plant can generate 1.3 tonnes of superheated steam at 40 kg/cm2g and 400 °C per tonne of sulphuric acid produced. It can also generate 0.3 to 0.5 tonne of low-pressure saturated steam at about 10 kg/cm2g. High-pressure superheated steam is utilised to run condensing turbines and generate electric power. Low-pressure steam is used in the plant for sulphur melting, deaeration and process heating.

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Reducing emissions from oil sands

Summary

Syncrude's Mildred Lake facility near Fort McMurray, Alberta, has recently undergone a multibillion-dollar expansion to increase production of synthetic crude oil. Flue gas desulphurisation facilities are a fundamental requirement to reduce SO2 emissions. Sulphur reports on the technologies being employed.

Abstract

Oil sand is composed of sand, bitumen, mineral rich clays and water. In its raw state, bitumen is a black, asphalt-like oil. The written history of oil sands dates back over 200 years when the first Europeans spotted bitumen along the riverbanks of the Athabasca River. The local Ab­original people had already been tapping the resource to waterproof their canoes.

Bitumen requires upgrading to make it transportable by pipeline and usable by conventional refineries. The upgraded bitumen consists of naphtha, light and heavy gas oils that are combined to produce a light sweet crude oil.

Today, Canada’s oil sands are the second largest known hydrocarbon reserves in the world. According to a recent report by Canada’s National Energy Board, Alberta’s bitumen production from oil sand is expected to almost triple by 2015 to 3 million b/d. Increased oil sands production also means an increase in sulphur production. By 2015, the report estimated that Canadian sulphur production could rise to 5 million t/a.

The Syncrude Project produces crude oil from oil sands found in the sub-Arctic climate of Northern Alberta, Canada. Syncrude Canada Ltd, a joint venture of nine organisations, is the world’s largest producer of crude oil from oil sands and the largest single source producer in Canada.

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Debut for clean diesel

Summary

Regulations limiting sulphur in on-road diesel are coming into force, but not without a few complications in the supply chain.

Abstract

When the Sulphur 2006 conference moves into action in Vienna in late October, fuel suppliers in the US will be a week past deadline to adapt storage tanks at bulk plants, retail outlets and wholesale storage sites to carry on-road diesel fuel with a sulphur content of 15 parts per million (ppm). US refineries have done the job of adapting their fuel streams to all-but remove sulphur from their product, and America’s attempt to develop a warm relationship between drivers and diesel fuel will be under way.

Diesel engines are much more efficient than gasoline-fuelled engines. Vehicles powered by diesels have 20 to 40 per cent better fuel economy than their gasoline-powered equivalents. Even greater fuel savings may result from diesel-electric hybrids now under development by vehicle manufacturers. However, gasoline is by far the fuel of choice for domestic consumers.

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Alumina Claus catalysts – are they still worthwhile?

Summary

Despite the growing trend for titania catalysts in Claus sulphur recovery units, the future of alumina catalysts is by no means over. Oleg I. Platonov, Senior Researcher at Gipronickel Institute, St Petersburg, reports on the latest industrial experience of catalyst aging with alumina catalyst AO-MK-2.

Abstract

In recent years, titanium oxide catalysts have become increasingly popular and have gained widespread acceptance as a replacement for conventional alumina catalysts in Claus units. However, successful experience gained with industrial alumina catalysts makes one question whether they really have become out of date.

It is generally accepted that the activity of Claus alumina catalysts is determined by its specific surface area and its resistance to sulphation1. Superficial sulphates inhibit the hydrolysis of sulphur-organic compounds (CS2 and COS). Therefore, Claus catalyst aging is often controlled based on CS2 ­conversion2,3.

The validity of this theory has been checked using data from AO-MK-2 alumina catalyst4 (granules 5-10 mm in diameter, content of +6.6 fraction making up 99.59 %) installed in a Claus reactor at Magnitogorsk Metallurgic Combine (MMC)’s By-product Coke Plant (BCP); the data were collected during the period beginning of April 2003 until the end of June 2006. The activity characteristics and coefficients of catalyst deactivation have been defined for AO-MK-2 in a commercial Claus process.

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ASRL Review

Summary

Oil sands bitumen: opportunities and challenges

Abstract

Peter Clark, Technical Manager, ASRL and Professor of Chemistry, University of Calgary, explains a role for sulphur in a Canadian bonanza.

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Chile expands smelter acid production

Summary

Chile's domination of smelter acid production in South America is scheduled to accelerate in the coming decade, and so is the country's demand for sulphuric acid to feed northern leaching operations.

Abstract

Production of smelter acid in South America is dominated by Chile, which produces around three-quarters of the continent’s output, mainly from smelters operated by the state copper company Codel­co. However, and in spite of its status as a world-leading producer of smelter acid, Chile is a net importer.

The country’s maturing copper industry relies increasingly on leach operations based on copper oxide ores, hence the balance between acid-producing smelters and acid-consuming leach operations increasingly favours the demand side. Additionally, the largest exploitable copper oxide deposits are found in the north of the country whilst the greater part of smelter acid output is significantly further south, so the costs of transporting Chilean smelter acid to leach operations are high.

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Shipping acid in

Summary

One of the world's busiest trading areas for sulphuric acid is among the coldest and iciest in the northern winter months. A consignment of new ships ordered by one of the area's leading sea-carriers of bulk liquid chemicals is designed to deal with the most challenging of conditions.

Abstract

Scandinavia’s base metals industry is one of the world’s leading sulphuric acid-producing regions. Conditions for transporting the industry’s metallurgical acid by-product to overseas markets can also be among the most challenging, with frozen harbours a regular feature of the northern Baltic coastline during the winter.

As trade grows in demanding materials such as concentrated sulphuric acid, so the demands made on the vessels transporting these materials become tougher. Anders Utkilens Rederi (“Utkilen”), one of the region’s leading carriers by sea of bulk chemicals – including sulphuric acid – has taken up the challenge by ordering three new ships. Their innovative storage and materials handling characteristics represent a new generation of specialised shipping in a very cold climate for chemicals such as sulphuric acid.

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Sulphur at a premium

Summary

The widely-accepted definition of "premium" product does not always allow for real conditions encountered during handling and storage. Gerard E d'Aquin of Con-Sul, Inc offers some ideas for a modified approach to the premium specification.

Abstract

Readers may recall Premium advice (Industry Comment, page 44) from Sulphur’s May-June 2006 issue. The column proposed the need to re-examine SUDIC’s (Sulphur Development Institute of Canada, which is no longer in operation) 30-year-old “Premium Sulphur” standard. This article pursues the proposal further, reviewing the goals behind SUDIC’s excellent work and changes in sulphur handling technology, providing examples taken from field sampling over the past few months, and making some recommendations.

Results presented here are intended to provide a perspective on issues believed to be relevant. More discussion will be provided by the author during the paper Sulphur forming with a different twist, a paper to be given at the Sulphur 2006 conference in Vienna.

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