Synthesis Gas Purification

Synthesis Gas Purification by PSA Process

Synthesis gas is a gas mixture which contains varying amounts of carbon monoxide and hydrogen that is generated by the gasification of a carbon containing fuel to a gaseous product. Examples are steam reforming of natural gas or liquid hydrocarbons that produces hydrogen, the gasification of coal etc. The name synthesis gas is derived because of their application as intermediates in producing synthetic natural gas.

Synthesis gas contains primarily carbon monoxide, carbon dioxide and hydrogen. Synthesis gas has a wide use as it is combustible in nature. It is often used as a source of fuel or as an intermediary for production of other chemicals. The use of Steam Reforming process to produce Synthesis gas is discussed here.

Steam reforming is basically a catalytic reaction that has the capacity to convert steam and hydrocarbon natural gas like methane into synthesis gas(Carbon monoxide) and Hydrogen. This is a process that is most commonly carried out by pressure swing adsorption (PSA) with molecular sieves being used for the final purification. The PSA technique is applied to adsorb all impurities from the synthesis gas stream to finally leave a pure hydrogen gas. Molecular sieve has the capacity to preferentially adsorb gas molecules down onto their surface. This is used by the PSA to separate hydrogen from synthesis gas. The impurities that are present in the feed gas are adsorbed by the carbon or Zeolite crystals as the case may be leaving hydrogen at the vessel. This hydrogen is removed as the purified hydrogen product.

Image of synthesis gas purification by PSA process: