Catalytic Upgrading of Plastic Waste of Electric and Electronic Equipment (WEEE) Pyrolysis Vapors over Si–Al Ash Pellets in a Two-Stage Reactor

Abstract

This study investigated thermal cracking and catalytic upgrading of waste from electric and electronic equipment (WEEE) plastics on a semi-batch reactor coupled to a heated catalyst fixed bed (2-stage vapor cracking). The catalyst used is a Si–Al ash obtained from commercial activated carbon pellets treated with concentrated NaOH solution and calcination. The purpose of the study was to characterize the waste stream through its thermogravimetry analysis and pyrolysis products, study the effect of temperature (350–500 °C) and catalyst quantity (0.0–7.5 %.wt) on yields of reaction products, physical chemical properties, and chemical composition of bio-oil in order to understand and evaluate production of fuels and chemical feedstock by recycling of WEEE plastic through catalytic upgrading. Time-fractioned samples were taken in determined reaction times (15, 30, 45, and 60 min) to study the evolution of cracking reactions during experiment runs through changes to chemical composition (GC/MS). A comparison with other previous work is also presented to show similarities between different feedstocks using the same thermal unit. The results indicate composition of brominated acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), and high impact polystyrene (HIPS) for the WEEE plastic. The temperature of 350 °C produced better results when considering acid value but presented lower bio-oil yields (38%) and high gas yields (42%). Catalytic upgrading experiments revealed the increased presence of polycyclic aromatic hydrocarbons (PAH) with an increase in viscosity of bio-oil, increase in char yield (from 11% to 24%), and decrease in gas yields (15% to 5%). Chemical composition showed presence of aromatic hydrocarbons such as styrene, methyl-styrene, and diphenyl-propane and nitrogenated compounds such as benzene-butane-nitrile, phenolic compounds, PAHs, and brominated compounds. WEEE plastic pyrolysis is a challenging subject due to contaminant presence and varying composition, and chemical composition evaluation according to reaction time provides interesting insights into the evolution of semi-batch pyrolysis/catalytic upgrading experiments. Standardization and reproducibility of the tool should be conducted to continue the evaluation of pyrolysis and catalytic upgrading of a wide range of feedstocks.

Depolymerization of PMMA-Based Dental Resin Scraps on Different Production Scales

“…Unlike on the technical and pilot scales, the reactor temperature thermocouple was situated outside of the reactor, and actual reactor temperatures were possibly lower, while for the technical and pilot scales, the thermocouple is situated in the center of the fixed bed, and temperatures at the edges of the reactors are higher than the setpoint of 450 • C, augmenting the production of side products in liquid and gaseous phases. The slower heating rates in the larger fixed bed of PMMAW also increased char yields with process scale, corroborating what is observed in academic literature for many types of materials [55][56][57]. Since pyrolysis process products are influenced by temperature and heating rates, it can be concluded that the characteristics of the feed such as specific heat, thermal conductivity and particle size and the characteristics of the process such as reactor geometry, heating mode and residence time are connected to temperature effects, influencing the yields of products.…”

“…All three fixed bed pyrolysis plants were accurately described in previous works [9,[55][56][57][58][59][60][61][62][63]. Basically, the three reaction systems are constructed based on a classic semibatch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water.…”

“…Basically, the three reaction systems are constructed based on a classic semibatch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water. The condensate and gases are separated in another vessel, where the liquid fraction is collected and the non- All three fixed bed pyrolysis plants were accurately described in previous works [9,[55][56][57][58][59][60][61][62][63]. Basically, the three reaction systems are constructed based on a classic semi-batch pyrolysis system (Figure 2) composed of a heated temperature-controlled fixed bed reactor coupled with a tube condenser operating with cooling water.…”

Improving the Antioxidant Activity, Yield, and Hydrocarbon Content of Bio-Oil from the Pyrolysis of Açaí Seeds by Chemical Activation: Effect of Temperature and Molarity

“…An overall mass balance was performed in order to calculate the quantity of gas formed. Basically, the weights of feed, bio-oil, aqueous phase, and coke formed are recorded, and a global integral mass balance calculation yields the quantity of gas formed by difference [85,86]. A differential mass balance of the considered system is described by Equation (1):…”

Improving the Antioxidant Activity, Yield and Hydrocarbon Content of Bio-Oil from Açaí Seeds Pyrolysis by Chemical Activa-Tion: Effect of Temperature and Molarity

“…An overall mass balance was done in order to calculate the quantity of gas formed. Basically, the weight of feed, bio-oil, aqueous phase and coke formed are recorded and a global integral mass balance calculation yields the quantity of gas formed by difference [54][55]. A differential mass balance of the considered system is described by the following equation ( 1):…”