Requirements for fresh hydrogen in hydrorefining cracking

The purity of the recycled hydrogen is 80-95%. The requirement for carbon monoxide is no more than 50 mg/m3.

It is generally in the range of several dozen ppm; too high a level leads to excessive heat release during the methanation reaction

Generally, the purity of reforming hydrogen in petrochemical plants is high, and the impurity content also meets the specified standards. The hydrogen obtained through dry gas recovery and separation has a complex origin, and sometimes certain impurities exceed the allowable levels; in such cases, physical or chemical methods are required to properly purify the hydrogen. If hydrogen is produced from coal, the conversion process must be strictly controlled to ensure that impurities do not exceed acceptable levels. If it’s electrolytic hydrogen, then just use it directly.

I would like to ask about the specific minimum requirements for the levels of carbon monoxide and carbon dioxide in new hydrogen, as well as the impact of carbon monoxide and carbon dioxide on the hydrogenation process

1. CO and CO2 carried in hydrogen reduce the hydrogen partial pressure. 2. When the content of CO and CO2 carried in hydrogen reaches 1%, methanation reactions occur on the surface of the catalyst at 200–350°C in combination with hydrogen, releasing a large amount of heat, which can easily lead to the formation of hot spots. Nickel carbide is formed on the surface of the Ni catalyst at 150°C. 3. CO tends to adsorb at the edges surrounding the Mo atoms, hindering reactions such as desulfurization and olefin saturation on the catalyst surface, which can cause temporary poisoning of the catalyst. For Co and Mo catalysts, 1000 ppm of CO is equivalent to an activity loss of 5–6°C. 4. The presence of Cl in hydrogen can cause corrosion and salt formation. 5. The concentrations of CO and CO2 in hydrogen are generally less than 20 μg/g. Cl is generally less than 1 μg/g