Crude oil to hosiery in one step?

John Meurig Thomas finds porous materials can cleanly catalyst hydrocarbon conversions

A new class of microporous catalyst can convert raw cyclohexane from the petroleum industry to adipic acid, the starting material for nylon and many other products, in one easy step without the need for the highly polluting oxidation stages.

Adipic acid is a common industrial building block for for many products, including products, for example synthetic material and fibers such as Nylon � the material from which women's hosiery is made. Adipic acid is usually generated from from cyclohexane but this requires several steps including oxidation.

	Adipic acid from oil to stockings

Now, John Meurig Thomas's team are finding ways to convert saturated hydrocarbons to useful products in one step using nothing much more than thin air.

Meurig Thomas's team has come up with a microporous aluminium phosphate catalyst in which a small portion of the aluminium is replaced by iron ions. These sit on the interior walls of the pores and provide an active centre on which reaction can occur. By carefully tuning the shape and size of the pores the team can control overall selectivity of their catalyst too. Only products with the right molecular shape and size can exit the pores, whereas cyclic intermediates are trapped inside until they the conversion is complete.

Click on picture to get molecule in ChemSketch format.

The linear chains of adipic acid and linear by-products, on the other hand, are flexible enough to leave the pores. "The primary goal of our work was to deliver a design prototype," explains Meurig Thomas, "many new catalysts for the environmentally friendly conversion of organic molecules should be based on this," he adds. The group has already taken the next step and swapped the iron for cobalt and tailored the pore-size to suit hexane: this in turn allows them to obtain appreciable quantities of adipic acid directly from hexane. The researchers point out that the ultimate goal would be to obtain methane by a similar process in a single catalytic step.

Reference:
Angew. Chem. Int. Ed., 2000, 39, 2310 and 2313.