Pyrolysis of Polyolefins in a Conical Spouted Bed Reactor: A Way to Obtain Valuable Products

Abstract

The amount of waste plastic increases every single year, which causes a critical environmental issue. Polyolefins (mainly high-and low-density polyethylene and polypropylene) are the most common types of plastics, accounting for 60 wt% of the plastic waste. Pyrolysis, the thermal degradation in an inert atmosphere, is considered to be one of the most appealing technologies for the recycling of plastic materials. The conical spouted bed reactor is suitable for the pyrolysis of plastic waste due to its ability to avoid agglomeration problems that may be caused by the melted plastic. The pyrolysis process may be carried out at different temperatures and with or without the presence of catalysts in the reaction environment in order to streamline product distribution. The resulting products are hydrocarbons: non-condensable gases (C 1 -C 4 ), gasoline fraction, diesel fraction, and waxes. These fractions might be used directly as feed streams for refinery units or as pools to be mixed with other streams from refineries.

Expanding Plastics Recycling Technologies: Chemical Aspects, Technology Status and Challenges

“…Cyclic and vigorous movements by sand particles in the bed prevent agglomeration upon melting and subsequent bed defluidization. 275,337 Conical spouted beds have been employed in laboratory-scale pyrolysis studies of PS 338 and polyolefins, 337,[339][340] which report high yields of wax. Orozco et al 275 identified stable operating conditions for conical spouted bed reactors for individual plastic feedstocks.…”

Expanding plastics recycling technologies: chemical aspects, technology status and challenges

“…Cyclic and vigorous movements by sand particles in the bed prevent agglomeration upon melting and subsequent bed defluidization. 259,326 Conical spouted beds have been employed in laboratory-scale pyrolysis studies of PS 327 and polyolefins, 326,[328][329] which report high yields of wax. Orozco et al 259 identified stable operating conditions for conical spouted bed reactors for individual plastic feedstocks.…”

Thermochemical Recycling of Waste Plastics by Pyrolysis: A Review

“…Also, the design of CSBR prevents agglomeration of sticky solids at the surface unlike a conventional fluidized bed reactor, thus allowing simpler operations. 205 Soharabi and co-workers 206 studied the kinetics of PET pyrolysis in a spouted bed reactor, wherein the activation energies of feed particles of sizes 0.1−1.0 and 1.0−3.0 mm were determined as 276.8 and 264.3 kJ/mol, respectively. The study concluded that heat and mass transfer limitations in spouted bed reactors could be minimized.…”

“…The advantages of high heat and mass transfer, low residence time, and improved product quality remain the same as a fluidized bed reactor. Also, the design of CSBR prevents agglomeration of sticky solids at the surface unlike a conventional fluidized bed reactor, thus allowing simpler operations …”