Catalytic pyrolysis of recycled polypropylene using a regenerated FCC catalyst

Abstract

The increasing generation of plastic wastes forces us to search for final disposal technologies environmentally friendly such as pyrolysis, which becomes an interesting technique because it takes advantage of the wastes obtaining important products. In addition, catalytic pyrolysis by using commercial catalysts, e.g. such zeolites, alumina or recovered from other industrial processes, it allows decreases the activation energy and selectivity in the obtained products. In this study, we report the evaluation of the catalytic pyrolysis with a regenerated fluid catalytic cracking catalyst using thermogravimetry with polypropylene and a pyrolytic process carried out in a batch reactor with polypropylene in a 1:10 ratio (catalyst-plastic). The regeneration studies were carried using two solvents (ethanol and toluene) at different contact times, then a thermal regeneration at two heating ramps was performed and the best treatment was evaluated by scanning electron microscopy energy-dispersive X-ray spectroscopy and surface area analysis. The results showed a better action of the ethanol in the chemical treatment at 14 h of contact in the heat treatment due to longer gasification of the coke. The degradation process using recovered catalyst decreases the degradation temperature compared to the no-catalyst process. As a consequence, the yield of the liquid fraction decreases by 10% with greater orientation to aliphatic components. Graphical abstract

Synthesis and Application of ZSM-5 Catalyst Supported with Zinc and/or Nickel in the Conversion of Pyrolytic Gases from Recycled Polypropylene and Polystyrene Mixtures under Hydrogen Atmosphere

“…Moreover, this process has the potential to reduce the carbon footprint of plastic products by reducing carbon dioxide and carbon monoxide emissions [ 6 ]. Previous works investigating thermal [ 7 , 8 ] and catalytic [ 9 ] pyrolysis have shown its potential, as well as the optimal operating conditions for the recovery of cleaner energy from plastic waste [ 6 , 10 ] or specific mixtures [ 7 ]. However, there is currently great interest, especially in catalytic pyrolysis, due to its great advantages, which include the following: (i) it accelerates the reaction rate of the process, allowing a greater depolymerization of the raw material; (ii) it reduces the energy necessary for the degradation of plastic waste; and (iii) it provides greater selectivity to obtain higher-quality pyrolytic products [ 11 ].…”

“…Among the catalysts used in this process are recycled catalysts from fluid catalytic cracking (FCC) units [ 9 ], red mud [ 13 ], ruthenium homogeneous catalysts [ 14 ], nanocatalysts [ 15 ] and natural or synthetic zeolites [ 16 , 17 ]. Many researchers have shown that zeolites present a greater potential due to their acidic properties, unique pore size, and large surface area, and they are much more active in the catalytic pyrolysis of different thermoplastics such as polypropylene (PP), polystyrene (PS), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and polyvinyl chloride (PVC) to obtain aromatic hydrocarbons [ 18 , 19 ].…”

Characterization of Equilibrium Catalysts from the Fluid Catalytic Cracking Process of Atmospheric Residue

“…The calculated values of microporosity show that the microporosity of the regenerated catalyst (49.79%) is higher than that of the fresh and spent catalyst (40.39%) and (49.73%), respectively, which is due to the presence of a large mesopore peak of 318.66 Å created by the effect of regeneration gas flow [1,24,35]. However, based on the values for the surface area and porosity of the regenerated catalyst compared to the values of the spent catalyst, it was found that there is a limit to the inverse relationship between surface area and porosity (the surface area of the catalyst decreases while its porosity increases) [36].…”