Catalysis is one of those rare scientific concepts that has entered common parlance. To lay people, catalysts initiate reactions. To chemists, surface physicists, and material scientists they're much more interesting. A catalyst increases a reaction rate without itself being consumed. Often it stabilises a critical reaction intermediate by trapping it on a surface, in a network structure, or by a precise lock-and-key fit. Reactions may involve cracking or synthesising organic chemicals, but catalysts can be inorganic, organometallic--or even biological, as in enzymes and catalytic antibodies. To be useful, catalysts must be engineered into practical processes, and their performance precisely measured and analysed. Increasingly, they are designed using advanced imaging and modelling. And yet, with all these scientific tools, making catalysts is still something of a black art.
But black art or not, catalysts are big business. The market research firm Frost & Sullivan calculates that sales of catalysts to the global chemical industry reached $8.5 billion in 2000--not counting catalysts made by companies for their own use and the growing markets for biocatalysts and environmental catalysts (such as those fitted to car exhausts or oil refineries). Dr Ewald Gallei, senior vice president of catalysis research at the German chemical giant BASF, reckons that 80% to 90% of chemical processes involve catalysis.
It's a field where even long-established processes and catalysts benefit from continued development. Ziegler and Natta's aluminium- and titanium-based catalysts drove the bulk manufacture of polyethylene and polypropylene in the 1950s. Subsequently, the Union Carbide (now Dow Chemical) Unipol process, developed in the 1970s, halved the capital cost of polyethylene plants and reduced their energy consumption by 75%. Then metallocene catalysts developed by Dow and others in the 1990s facilitated the manufacture of new forms of these plastics.
Economics also drive change. Most catalytic converters on cars are Pt-Pd-Rh mixtures. When rhodium prices rocketed in 1990 makers used more palladium, but when palladium prices began to rise, reaching record levels in 2001, this had to be reversed--a new catalyst developed by Degussa of Germany reportedly allowed General Motors to reduce palladium usage by 40% to 60%.
A Changing Industry
Recently, the shape of the sector has been changing in Europe. Synetix was created when UK-based chemical group ICI merged the catalyst business of Anglo-Dutch Unilever (including its margarine catalysis concern) with its own operations and some other purchases. Last year, ICI sold Synetix to Johnson Matthey, a UK-based precious metal refiner and catalyst specialist. Others have been buying and selling businesses: Degussa sold its precious metal and catalyst business to OM Group of the United States, while Engelhard of the U.S. has bought businesses from Süd-Chemie and Targor of Germany.
Participants see this as a sign of vibrancy: "We believe that catalysis as a marketplace is growing", says Dr Brian Harrison, new business development director for Johnson Matthey Process Catalyst Technology at Royston, UK, citing the new opportunities to convert old processes into more efficient catalytic ones. "Also, you can't be stuck in one corner of catalysis. Johnson Matthey was very much a precious metal company, and what we now have is a precious metal and base metal process catalysis business that gives us tremendous strength and the opportunity for synergies between the two". For example, there are crossovers between hydrogenating edible oil to make margarine and equivalent reactions in the petrochemical industry.
Precious metal refiners such as Engelhard, Degussa, Johnson Matthey, and W. C. Heraeus of Germany entered the catalysis market place because it represents an important end-use for their metals. Millennium Chemicals makes titanium compounds, so naturally it sells the TiCl4 Ziegler-Natta catalyst. Companies such as Dow Chemical and ExxonMobil (petrochemicals), AkzoNobel and BASF (organics), and Albemarle and Rhodia ChiRex (specialities) needed catalysts for their own processes. Other companies (e.g., UOP, Grace Davison, and Haldor Topsøe) specialise in developing and licensing chemical process technology. Perstorp developed a commercial environmental catalyst business out of its in-house efforts to control emissions from its formaldehyde plants. Many oil and chemical companies have catalyst teams even though they don't market them.
Catalyst development runs from fundamental research through product development to pilot plant testing and technical service on the customer's plant. David Prest, technical director for Johnson Matthey Process Catalyst Technology at Billingham, UK, says, "The work is directed by what the marketplace and individual customers require. It's an exciting time and there are rapid changes. But these are very significant projects that can go on for a period of years". Harrison agrees, but points out that there can be differences between the 'R' and the 'D' side: "Research projects can be quite long-term--you may be working on a project for 2 to 3 years--or even make a lifetime of working in one area. Whereas in development, while you may be on a project for a couple of years for a major customer, you might be on another project for a month. A customer might go away and you have to swallow hard and move on to something else".
Close collaboration with the customer's scientists is essential. Johnson Matthey recently built a plant to manufacture PdCl2 catalysts for two new BP processes--the Leap vinyl acetate monomer process, and the Avada ethyl acetate process. BP discovered the basic catalysts, but Johnson Matthey made them capable of being manufactured. Now BP and Johnson Matthey scientists are working as single teams to develop these further.
Despite economic difficulties in much of the chemical industry, several catalyst-makers continue to invest in research. Two years ago Süd-Chemie opened new labs in Heufeld, Germany, that created 20 new jobs for highly qualified scientists. Meanwhile, the chiral technology business of Synetix (now Johnson Matthey) has been growing rapidly. Rather than build additional labs at its main research centre in Billingham, NE England, it established a group of about 10 scientists at Cambridge Science Park. This not only gives them access to the university, but brings them closer, geographically, to many of their pharmaceutical industry customers.
BASF's catalyst unit supplies outside firms as well as the company's own plants--often, a BASF plant is the test market--and it works with some of the largest chemical engineering firms. Including technicians and shift workers on the pilot plants, BASF already employs 500 to 600 people in catalysis R&D in Ludwigshafen, Germany, and the number is growing. It recruits researchers mainly at the PhD level, across a range of disciplines: solid state chemistry, organometallic chemistry, surface science, and--importantly--chemical engineering. They work in interdisciplinary teams, but each scientist needs to learn something of the other specialisations to understand catalysis. "We need team-oriented people with communication skills, and people with the potential for entrepreneurial thinking", says BASF's Gallei (see profile of Henrik Junicke).
Johnson Matthey "is always looking for excellence, and sees recruitment as a global exercise", says Prest. "We have many different nationalities working in our R&D". Like BASF, the company recruits R&D scientists predominantly at the PhD level, whereas engineers tend to join as graduates and then work to become chartered. They also hire materials scientists and even mathematicians for the modelling work. (See box for links to the recruitment sites of companies across the sector.) What enthuses people, he says, is seeing the fruits of their labours--such as a new car catalyst--on the market on a timescale of a couple of years. Another popular aspect is 'greenness'--catalysts mean lower energy, cleaner processes, and environmentally friendly technologies such as fuel cells (see profile of Sarah Ball).
Catalysis also brings big scientific challenges. Traditionally, industrial processes use heterogeneous catalysts, where reactants pass through a bed or gauze of solid catalyst. But most lab reactions use homogeneous catalysts (in the same liquid phase as reactants and products). This means that valuable catalyst either remains in the product or has to be expensively separated. For pharmaceuticals especially, it is not good to have catalyst contaminating the product. Prest and Gallei agree that converting homogeneous processes into heterogeneous ones is a major target of R&D efforts, for example by immobilising the homogeneous catalyst on a solid support. And because life has a preferred handedness, reactions that make both right- and left-handed compounds waste half the product. So companies serving the life science industry, such as Rhodia ChiRex, ChiroTech (now DowPharma), and Johnson Matthey are rushing to develop the kind of stereoselective catalysts that won Sharpless, Noyori, and Knowles the 2001 Nobel Prize for Chemistry.
Other advances are changing research itself. Despite all the modelling, researchers still have to crank through many samples to find the best combination of properties. The catalysis sector has therefore followed drugmakers into combinatorial chemistry and high-throughput screening techniques. Symyx Technologies has developed these technologies to speed up catalyst development and has agreements with Dow, the German polymer-maker Celanese, and the Swiss speciality chemical firm Lonza, among others.
Dr Barry Murrer, director of Johnson Matthey's Technology Centre at Sonning Common, UK, says the biggest change [in catalyst R&D] has been in instrumentation. "We can now start to understand the properties down to the nanoscale. Once you understand what's happening, you can start to control the chemistry. It may be possible to design a heterogeneous catalyst rather than rely on empirical development--less of the black art!" For example, there has been a move away from classical surface science on clean surfaces. "Working catalysts are not simple surfaces, but it's now possible to use molecular beam technology to place well-characterised clusters of metal atoms onto a surface", says Prest. "The challenge for nanotechnology is to convert that to something that can be produced on a commercial scale. We are coming into an era of designer catalysts," he says, "catalysts are very contemporary science."