Route to success

23 September 2002 17:27  [Source: ICB]

UK methacrylates producer Lucite aims to expand its interests in acrylic resins and polymers and has focused on improving the manufacture of MMA. Persistence has paid off with its patented Alpha process, as John Baker reports

There's a palpable feeling of excitement in the air at the new Wilton, UK, technology headquarters of Lucite International, the leading methacrylates producer. The company's long-running development of an innovative ethylene-based route to methylmethacrylate (MMA) monomer is finally coming to fruition.

Separate trials on the two reaction stages in the process are now under way on fully integrated and instrumented pilot plants at Wilton and Stockton, both on Teesside. The latter has been designed and built and is operated in collaboration with Davy Process Technology.

Success, believes Lucite, will create a step-out improvement in the economics of MMAmanufacture and secure it a leading-edge advantage in the production of acrylic resins and polymers. The company already holds a 25% share of the global acrylics market and is looking to build on this strong position.

The prospect of a worldscale 100000 tonne/year plant coming onstream in 2006 in the US, with at least a 20% cost advantage over a conventional unit based on acetone cyanohydrin (ACH) or C4 feedstocks, should generate added interest in the flotation of the $1bn turnover company, plans for which were revealed in May (ECN 13 May 2002).

Research on the new route, dubbed the Alpha process, started some ten years ago, when the acrylics business was still part of ICI. In the intervening years, the business has been merged with DuPont's acrylics operations (1993) and then sold by ICI to Charterhouse Development Capital (1999).

Since then, it has operated as Ineos Acrylics until its recent rebranding prior to the flotation, expected within the next few years. Throughout these changes, the development of the technology has received full support, disproving the notion that venture capitalists run companies purely for the short-term benefits to be had from cost savings and strict financial controls.

The Alpha process consists, in essence, of three steps:two separate catalytic reactions and a complex series of distillations in the final product separation stage. Development of the two catalysts and the separation stage have all been central to realising the process, and each is covered by a number of key patents.

In the first stage, readily available feedstocks ethylene, carbon monoxide and methanol are reacted in the liquid phase at very mild conditions (10 bar and 100degC) over a homogeneous palladium-based phosphine ligand catalyst, to produce methylpropionate (MeP), with essentially no by-products.

The MeP is then used in the second step, to react with formaldehyde in the gaseous phase over a fixed bed heterogeneous catalyst in the presence of methanol, to produce MMA and water. Reaction conditions are 320ûC and 2 bar, and the reaction selectivity is 95%. It is important to keep the water content to a minimum to avoid co-production of methacrylic acid, which is why methanol is added to drive the reaction to MMA.

The MMA is then separated from the other constituents using six distillation steps, ultimately producing a product stream, recycle stream and waste stream. Two of the distillations remove water from the reaction, also to prevent methacrylic acid formation, while the other four give the pure MMAstream and recycle stream.

The novel separations process is complicated and includes reactive distillation steps involving formaldehyde. The overall setup and control is thus complex, but it is one Lucite has now built up six years' of experience with and has protected with several patents.

The overall approach has a number of advantages over the conventional routes to MMA, explains Neil Sayers, vice president manufacturing, technology and SH&E for Lucite. The process is much lower cost in terms of capital investment and feedstock, does not require a large inventory of sulphuric acid, and has a high selectivity to the end product, with no solids or polymer formation. In addition, the commercial plant will use relatively simple stainless steel components.

With the trials under way, using ethylene straight from the nearby Huntsman cracker at Wilton, earlier work on the selectivity and stability of the catalysts has proved to be correct, giving the process a robust performance. Lucite is working with a selected number of catalyst producers to develop these catalysts further and to optimise the production processes for them.

For the first stage, for instance, the Pd/phosphine ligand catalyst has proven it has long life, with 1kg of the homogeneous catalyst capable of producing some 200 tonne of MeP. The second stage catalyst, a stabilised basic catalyst in the form of 3mm beads, now shows a two-year lifetime - a vast improvement on the four days for the initial version.

Data coming off the pilot plants since their startup in Q3 last year will be used for the front end engineering and design (FEED) of a fully commercial plant, with no intermediate scale-up necessary, says Sayers. This assumes a scale up factor of around 1:20 000.

Plans for the commercial unit are already forming, and Lucite has decided it will be most effective to build and run its own methanol-to-formaldehyde unit, using licensed technology to feed the second reaction stage, rather than buying in the material.

The MMAproduced by the 15kg/day pilot plant is now being put through product quality testing and has been polymerised into PMMAresin. This has itself been tested to see whether it performs as well as PMMAmade from conventionally produced MMA. Results, again, have proved encouraging, with an MMA purity of 99.95% achieved since April this year.

Further work for the rest of this year will concentrate, says Sayers, on catalyst usage optimisation in the first stage - seeking to modify the catalyst further to give greater stability - and on catalyst lifetime testing in the second stage. In addition, further MMA polymerisation testing will be undertaken.

Lucite is also still optimising the technology overall and continuing to characterise the process, so it can develop process models using AspenTech's software. Commenting on the likely timing of full scale commercialisation, Sayers indicates that a 2006 startup at a Lucite site in the US is within reach, with Beaumont, Texas, the favoured option given its ethylene pipeline connections and existing infrastructure.

A number of producers have indicated their intention to add capacity, some of which may materialise in the timeframe 2004-07. But the market should quickly absorb this capacity, given MMA demand growth rates of over 3%/year.

Lucite has MMAcapacity at Billingham in the UK, Memphis and Beaumont in the US, and at Kaohsiung in Taiwan, through its KMC joint venture with CPDC. After a recent expansion at Beaumont, the company operates just over 600000 tonne/year of MMAcapacity, feeding its own downstream needs and non-integrated downstream customers.

Lucite also has aspirations to build MMAcapacity in China, reveals Sayers, but this would be based on conventional technology. Local reports suggest a likely location is the new petrochemicals complex at Caojing, near Shanghai, where BP and SPC, via their Secco joint venture, are building ethylene and acrylonitrile capacity. The ACNplant would supply HCN feedstock for the ACH-based MMA plant.

Lucite uses MMA in a series of downstream material areas, many of which, says Rowena Sellens, global R&D director, are experiencing strong growth through product innovations. Over 20% of Lucite's sales come from products introduced over the last three years, she points out.

Besides PMMApolymer for injection moulding and cast and extruded sheet applications, Lucite produces speciality methacrylates and comonomer resins, composites - for use in baths and work surfaces - and effect chemicals. Total output is 850000 tonne/year (see table).

Sellens highlights recent developments in PMMApolymer processability, co-extrusion of PMMA capstock to improve PVCperformance, and improved optical properties and colour performance, in terms of weatherability. The aim, she says, is to increase the value to customers of acrylic materials 'and to allow access to the power of the Lucite and Perspex brands'. 'Customers are often buying for effect and we want to widen and enhance these via new aesthetics coupled with value-in-use,' she explains,

One rapidly growing area is use of PMMAin the optical media and electronics industries, as the backing sheet in liquid crystal displays. Other areas of innovation include acrylic process modifiers, used in PVC and polyester fibre production, and polymer blends, for instance of acyclic with PVC.

In the sheet area, Lucite is working to add antimicrobial and antifungal properties to acrylic sheet, as well as driving up its flame retardancy and impact performance.

In the speciality resins area, innovation is focused on improving performance in products such as adhesives, inks, coatings and dental and medical materials. Reactive polymers and polymers with architecture can be used for instance to reduce VOC content in adhesives and coatings.

With such product innovation soon to be backed by a low-cost source of in-house raw material, Lucite can afford to feel excited by its prospects. Company chairman and chief executive Scott Davidson, who has led the business for 11 years, says he hopes to grow the business rapidly both by organic and M&A routes prior to the planned flotation, taking turnover up by 50% in the process.

Charterhouse has not only backed the technology drive. In 2000 Lucite acquired Bonar Polymers in the UK and Acrylic Products in South Africa, and further such acquisitions can be expected, says Davidson. As he points out, acrylics are still, after 65 years, exciting and innovative and 'are more relevant to this century than last given acrylics' inherent properties and recyclability.'

Lucite's acrylics capabilities, tonne/year

	US		EU			Asia/ S Africa
MMA monomer	310		200		100
Speciality
methacrylates	60		40		-
Resins	15		10		-
Reagent and
ÊÊeffect chemicals	-		20		-
PMMA polymer	70		30		-
Sheet	70		35		25
Composites	-		20		15
SOURCE:LUCITEINTERNATIONAL

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