Hydrogen synthesis

A wide range and a number of purification steps are required to make available hydrogen/synthesis gas having the desired purity that depends on use. Technology is available in many forms and combinations for specific hydrogen purification requirements. Methods include physical and chemical treatments (solvent scmbbing) low temperature (cryogenic) systems adsorption on soHds, such as active carbon, metal oxides, and molecular sieves, and various membrane systems. Composition of the raw gas and the amount of impurities that can be tolerated in the product determine the selection of the most suitable process. 

AE Jackson, RAW Johnstone. Rapid, selective removal of benzyloxycarbonyl groups from peptides by catalytic transfer hydrogenation. Synthesis 685, 1976. 

Methyl alcohol (methanol) is manufactured from a mixture of carbon monoxide and hydrogen (synthesis gas), using a copper-based catalyst. 

The catalyst is poisoned by CO, C02, and H20 so they must be rigorously removed upstream in the hydrogen synthesis process. Oxygen molecules are permanent poisons. Other poisons such as sulfur, arsenic, halides, and phosphorous must be carefully removed upstream in as much as they too are permanent poisons. 

Catalytic steam reforming could also be performed on natural gas (mainly methane) or the heavy fraction of crude oil called naphtha or fuel oil. The old method of producing synthesis gas by passing steam over red-hot coke was noncatalytic. Depending on the requirement for hydrogen, synthesis gas could be further enriched in hydrogen by the following reaction ... 

In an ammonia plant (Figure 4.2), the synthesis gas from the reformer furnace is fed into a secondary reformer vessel, where air is added through a burner to create outlet vessel temperatures of -1,800° F (980° C). The outlet of the secondary reformer vessel is cooled in a quench steam generator and sent to a shift converter this is followed by a carbon dioxide removal system such as the one in a hydrogen plant. The purified nitrogen from the air added in the secondary reformer vessel and hydrogen synthesis gas is fed to a methanator to convert residual oxides of carbon back to methane (which is inert in the ammonia conversion) the gas is then compressed to -3,000 psia (2,070 kPa). The compressed synthesis gas is fed to an ammonia converter vessel. As the synthesis gas passes over catalyst beds, ammonia is formed. The ammonia product is then cooled and refrigerated to separate out impurities. 

Kvaerner Process Technology Amines, C, to C12, multiproduct Alcoh ol/alde hyd e/ketone/ ammonia/hydrogen Synthesis of mon, di or tri alkylamines by vapor-phase animation 9 1998... 

Kvaerner Process Technology Cyclohexanone/cydohexanol Phenol/hydrogen Synthesis of KA oil with high selectivity to cyclohexanone 2 1998... 

Hydrogen, synthesis gases and their deri auves... 

Hydrogen, synthesis eases and their derivatives Table 1.15... 

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