The influence of CHNOS analysis in the process of converting plastic waste into hydrocarbon feedstock
Chemical recycling solutions lead the way to the future.
Plastic pollution as a significant problem, consumers demand more sustainable products and packaging. In response, companies that manufacture everyday goods, see recycled plastics as a strategic differentiator. Only a small fraction of plastics can be mechanically recycled, the future lays in chemical recycling solutions. Producing oil from plastic waste such as polystyrene or flexible packaging seems to become an alternative “green” source of liquid hydrocarbon feedstock. This feedstock can be used as fuel or new polymer combinations.
The need for oxygen analysis is increasing
During the pyrolysis process temperatures can reach up to 400 °C . Before the recycled oil can be processed CHNOS content needs to be measured. The higher the C/H ratio of the pyrolysis oil, the more cumbersome and costly the refinery processing required to produce given volumes of gasoline and distillate fuels. Additionally, high concentrations of heteroatoms (i.e., sulfur, nitrogen, and oxygen) in the recycled feedstock are undesirable, since they can deactivate the catalysts, could cause corrosion in refinery equipment, and in the case of sulfur lead to air emissions that are subject to stringent regulatory controls.
While CHNS analysis of petrochemical feedstock has been performed for decades, the need for oxygen analysis is new and tied specifically to recycled feedstock. Whereas the oxygen content of crude oil is inherently low, recycled oil often has significant levels of oxygen. Therefore, knowing the exact oxygen content is helpful when deciding how to blend crude and recycled oil to arrive at an oxygen level that is acceptable for refinery processing. Furthermore, the presence of oxygen leads to CO2 conversion which decreases the octan number in fuel.
High precision CHNOS measurements with unbeatable low detection limits for oxygen analyses
Oxygen analysis is easily accomplished the rapid OXY cube. Within the analyzer, the sample’s oxygen is completely converted to the target analyze CO thanks to an extraordinarily high pyrolysis temperature of 1450 °C. It is this complete conversion that leads to highly accurate, highly precise, and matrix-independent analytical results. The rapid OXY cube eliminates interferences from pyrolysis byproducts. An optional IR-detector with high sensitivity and high linearity lowers the LOD of the rapid OXY cube to 10 ppm.
For CHNS analysis of oil samples the vario EL cube can also be used. The analytical results of this analyzer are based on superior combustion and peak separation. Furthermore, the vario EL cube utilizes 3 gas-separating columns. This results in an intelligent peak separation, which adjusts dynamically to each individual sample, and makes a big difference for the C-H peak separation of oil samples. Trace sulfur analysis is enabled by an optional IR-detector. The nitrogen content of oils tends to be low. Here, it is of advantage that the vario EL cube has extremely low nitrogen blanks as ambient air is effectively flushed away with our patented ball valve technology.
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