Oil refinery. This is the catalytic cracking area. Catalytic cracking uses high temperature and a catalyst to break down (crack) heavy oil fractions into lighter, more useful oils. The oil is heated to 500 degrees Celsius and passed over a catalyst such as zeolite crystals. The products from oil cracking are commonly blended together to add to a fuel such as petrol, or used as a raw material in the chemical industry. The vessel where the cracking takes places is the barrelshaped grey one that is just left of centre. Photographed at ExxonMobils Fawley Oil Refinery, Hampshire, UK.