Meaning
Silicon-bearing organic compounds derived from packaging lubricants and anti-foaming additives constitute harmful impurities in recycled plastic pyrolysis oil and monomer recovery streams. In polyolefin recycling plants, organosilicon contaminants decompose into solid silicon dioxide particles when subjected to elevated thermal processing temperatures. These impurities govern equipment fouling and haze formation in transparent molded packaging.
Application of removal protocols targets cyclic siloxanes and linear siloxanes prior to high-temperature furnace processing.
Catalyst Fouling
Thermal cracking of feedstocks containing siloxanes deposits amorphous silica films directly onto catalyst surfaces and furnace coil walls. Silica accumulation reduces thermal transfer efficiency in steam cracker radiant sections and blocks active catalyst sites in hydrotreating units. Unplanned shutdowns occur when pressure drops across packed catalyst beds exceed operational safety thresholds.
Refiners monitor silicon levels in incoming pyrolysis oils using atomic emission spectroscopy to enforce strict acceptance thresholds.
Optical Degradation
Residual organosilicon contaminants that survive cracking reactions pass into downstream polymerization reactors, forming microscopic silica domains inside the resin matrix. Molded film products exhibit surface haze and elevated gel counts due to these insoluble inorganic inclusions.
Adsorption Removal
Specialized guard beds packed with functionalized alumina or silica gel adsorb organosilicon contaminants from liquid pyrolysis oil prior to hydroprocessing. Sorbent replacement schedules depend on continuous monitoring of silicon concentration spikes.
