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Catalysts: speeding up chemical reactions
They are as small as a grain of rice, but just 150 grammes of them have the surface area of a football field. Catalysts speed up chemical reactions, and they are central to the process of converting natural gas to liquid fuels and other products.
Shell’s catalyst company, CRI/Criterion, has spent around four years using dedicated facilities in Europe in full-time production to provide the thousands of tonnes of catalysts that were needed for the start of production at Pearl GTL.
Combined, the total surface area of these catalysts will be equal to almost 18 times the size of the state of Qatar. On this scale, huge volumes of gas are exposed to the catalysts’ chemically treated surface, maximising the rate of chemical GTL-reactions. The vast surface area is the result of a catalyst’s many nano-sized inner channels, which create high porosity.
The catalysts will accelerate a reaction that will convert synthesis gas (a mixture of hydrogen and carbon monoxide) into the hydrocarbon molecules that form GTL wax — the basis for the production of the finished GTL products.
New cobalt catalyst
Advances in technology have been crucial to making the process work efficiently on a large scale. Among other things, Shell’s development of a new advanced proprietary cobalt synthesis catalyst has already significantly increased output of the GTL products on a commercial scale at Bintulu. The Pearl GTL plant’s 24 reactors will use this new catalyst.
“The more efficient the catalysts, the better the productivity of the project and the greater the financial return,” says Carl Mesters, Shell Chief Scientist Chemistry and Catalysis.
The catalysts are distributed throughout tens of thousands of tubes inside each 1,200-tonne reactor. They will be replaced every few years, one reactor at a time to minimise the impact on production. CRI/Criterion reclaims the cobalt inside used catalysts to make new catalysts.
For Shell, the start up of Pearl GTL was the culmination of more than three decades of research, the filing of around 3,500 GTL-related patents and the development of some of the world's most advanced cobalt synthesis catalysts.