Gas Phase Oxidation
In the production of short-chain petrochemical raw materials oxidation often occurs in the gas phase with molecular oxygen usually used. Process air is regularly the source of the oxygen.
In this case, oxygen in the form of process air, oxygen-enriched air or pure oxygen can be used. Increased oxygen content leads to a more compact design and can significantly increase the efficiency of oxidation reactions. For this reason, many of these oxidations are already carried out in industry with pure oxygen.
The use of oxygen has the following advantages compared to pure air operation:
- Compacter plant design
- Lower pressures required and thus savings in plant material
- Increase in selectivity and product yield
- Possible capacity increase
- Lower costs for product processing
- Greater flexibility in operation
With oxygen, the product yield in chemical processes can be increased significantly, thus saving valuable petrochemical raw materials. Gas phase reactions use the OxyCone™ feed system, which uses pure oxygen in a particularly efficient manner. In addition to the optimal entry system, other factors, in which Messer can provide sound expert knowledge, also play a decisive role.
In many processes, the oxygen process has even established itself as the market leader. Applications for oxygen- or oxygen-enriched air already exist in the following industrially used processes:
- Ethylene oxide (EO) through catalytic direct oxidation of ethylene
- Propylene oxide (PO) through catalytic direct oxidation of propylene
- Vinyl chloride monomer (VCM) through oxy-chlorination of ethylene
- Vinyl acetate monomer (VAM) through oxidative coupling of acetic acid and ethylene
- Acetaldehyde through gas phase oxidation of ethylene (Wacker-Hoechst process)
- Acryl nitrile through catalytic direct oxidation of propene and ammonia (Sohio process)
- Hydrocyanic acid through oxidation of ammonia and methane (Andrussow process)
- Hydrogen peroxide through direct elemental synthesis
When pure oxygen is used, substantial process improvements are possible as the inert gas component of the air, which acts as a "ballast", is eliminated. In the following processes, air is used for the most part and acts as an oxidiser in the heterogeneously catalysed gas-phase oxidations:
- Acrolein through oxidation of ethylene
- Methyl methacrylate (MMA) through oxidation of 1-butene
- Maleic acid and maleic acid anhydride (MSA) through oxidation of C4-fractions (raffinate II) or benzene
- Phthalic acid anhydride (PSA) through oxidation of o-xylol or naphthene
- Glyoxal through oxidation of ethylene glycol
An interesting example is the process for the production of ethylene oxide with pure oxygen compared to a process with atmospheric oxygen. Due to the clear superiority of the pure oxygen process, modern plants are only built for this method. Messer supplies large customers with oxygen and associated know-how for cost-effective oxygen supply and the optimal oxygen input for this process.