<P> This process was patented in 1831 by British vinegar merchant Peregrine Phillips . In addition to being a far more economical process for producing concentrated sulfuric acid than the previous lead chamber process, the contact process also produces sulfur trioxide and oleum . </P> <P> The process can be divided into five stages: </P> <Ol> <Li> Combining of sulfur and dioxygen (O) to form sulfur dioxide </Li> <Li> Purifying the sulfur dioxide in a purification unit </Li> <Li> Adding an excess of dioxygen to sulfur dioxide in the presence of the catalyst vanadium pentoxide at 450 ° C and 1 - 2 atm </Li> <Li> The sulfur trioxide formed is added to sulfuric acid which gives rise to oleum (disulfuric acid) </Li> <Li> The oleum is then added to water to form sulfuric acid which is very concentrated </Li> </Ol> <Li> Combining of sulfur and dioxygen (O) to form sulfur dioxide </Li>

Give the principle for the manufacture of sulphuric acid by contact process