This study investigated an efficient catalyst configuration to enhance the recycling of waste electrical and electronic equipment (WEEE) fractions into aromatic hydrocarbons. Two engineered WEEE fractions, low-grade (LGEW) and medium-grade (MGEW), were used as feedstock in an ex situ catalytic pyrolysis process conducted in a two-stage lab-scale reactor. The first stage involved a batch pyrolyzer, followed by a fixed-bed catalytic reactor. The interaction between catalyst active sites and pyrolysis vapors played a key role in determining the chemical functionality of the surface intermediates. Five catalytic modes were tested: CaO, HZSM-5, Fe/HZSM-5, and a combination of CaO and HZSM-5 in mixed and separate bed configurations, with a catalyst-to-feedstock ratio of 0.15 w/w. The iron-loaded zeolite favored gas production, while CaO effectively converted acids into ketones. The dual-catalyst mixed bed of CaO and HZSM-5 exhibited the best catalytic synergy, enhancing the production of aromatic hydrocarbons and decarbonizing the process. However, metal doping increased catalyst coke formation due to more Lewis acid sites and the production of polycyclic aromatic hydrocarbons. Overall, this study provides a comparative analysis of catalyst activity during the thermochemical conversion of WEEE.

Pyrolysis of biomass plus catalytic reforming of its pyrolysis volatiles is a green alternative to produce solid (biochar) and gaseous (syngas) fuels that have several valuable applications; however, this catalytic process suffers from fast deactivation, and its energy consumption is yet to be studied, factors that determine the process's feasibility in industrialisation. To address these issues, the direct electrification of a 3D-printed FeCrAl heater coated with 15.5 % Ni/Al2O3 was tested in a parametric study in the catalytic steam reforming of biomass pyrolysis volatiles, in order to investigate the effect of the S/B ratio and space–time on the syngas yield and composition. Complete bio-oil reforming was obtained at a biomass feed rate of ≤ 1 g min−1 and a S/B ratio of ≥ 2, and stability close to 100 % was estimated after over four hours of operation. Nonetheless, the produced syngas is rich in C1 – C3 gases and moderately low in H2 (≈ 2 wt %). The effect of the catalyst's structure on the bio-oil reforming and heat efficiency was complemented using CFD simulations and compared to a simple geometry based on commercial extruded monoliths. Finally, the biomass-derived syngas upgrading to H2 production was assessed using different process simulations and compared to existing H2-producing technologies in terms of energy efficiency and emissions.

Waste electrical and electronic equipment (WEEE) has become a critical environmental problem. Catalytic pyrolysis is an ideal technique to treat and convert the plastic fraction of WEEE into chemicals and fuels. Unfortunately, research using real WEEE remains relatively limited. Furthermore, the complexity of WEEE complicates the analysis of its pyrolytic kinetics. This study applied the Fraser-Suzuki mathematical deconvolution method to obtain the pseudo reactions of the thermal degradation of two types of WEEE, using four different catalysts (Al2O3, HBeta, HZSM-5, and TiO2) or without a catalyst. The main contributor(s) to each pseudo reaction were identified by comparing them with the pyrolysis results of the pure plastics in WEEE. The nth order model was then applied to estimate the kinetic parameters of the obtained pseudo reactions. In the low-grade electronics pyrolysis, the pseudo-1 reaction using TiO2 as a catalyst achieved the lowest activation energy of 92.10 kJ/mol, while the pseudo-2 reaction using HZSM-5 resulted in the lowest activation energy of 101.35 kJ/mol among the four catalytic cases. For medium-grade electronics, pseudo-3 and pseudo-4 were the main reactions for thermal degradation, with HZSM-5 and TiO2 yielding the lowest pyrolytic activation energies of 75.24 and 226.39 kJ/mol, respectively. This effort will play a crucial role in comprehending the pyrolysis kinetic mechanism of WEEE and propelling this technology toward a brighter future.

Ex situ catalytic pyrolysis of engineered waste electrical and electronic equipment (WEEE) was conducted in a two-stage reactor using HZSM-5 catalyst. The effect of the catalysis temperature and the catalyst-to-feedstock (C/F) ratio on products yield, gas and oil composition, and products characterization were investigated in this study. Results indicated that lower reforming temperature and C/F ratio favored organic fractions production. The highest yield of organic fraction was obtained at a catalysis temperature of 450 °C and at a C/F ratio of 0.15, corresponding to 28.5 and 27.4 wt %, respectively. The highest selectivity toward aromatic hydrocarbons and the lowest TAN value of the organic fraction were obtained at a catalysis temperature of 450 °C and a C/F ratio of 0.2, respectively. Most of the alkali and transition metals and 23 % of Br remained in the solid residue after the catalytic pyrolysis of low-grade electronic waste (LGEW).

Non-catalytic and catalytic pyrolysis of two waste electrical and electronic equipment (WEEE) fractions, with two different copper contents (low-and medium-grade WEEE named as LGE and MGE, respectively), were performed using micro-and lab-scale pyrolyzers. This research aimed to fundamentally study the feasibility of chemical recycling of the WEEE fractions via pyrolysis process considering molecular interactions at the interfaces of catalyst active sites and WEEE pyrolyzates which significantly influence the chemical functionality of surface intermediates and catalysis by reorganizing the pyrolyzates near catalytic active sites forming reactive surface intermediates. Hence, Al2O3, TiO2, HBeta, HZSM-5 and spent FCC catalysts were used in in-situ micro-scale pyrolysis. Results indicated that HBeta and HZSM-5 zeolites were more suitable than other catalysts for selective production of aromatic hydrocarbons and BTX. High acidity and shape selectivity of zeotype surfaces make them attractive frameworks for catalytic pyrolysis processes aiming for light hydrocarbons like BTX. Meanwhile, the ex-situ pyrolysis of LGE and MGE were carried out using HZSM-5 in micro-and lab-scale pyrolyzers to investigate the effect of pyrolysis configuration on the BTX selectivity. Although the ex-situ pyrolysis resulted in higher formation of BTX from LGE, the in-situ configuration was more efficient to produce BTX from MGE.

An ex-situ catalytic fast pyrolysis lab-scale setup consisting of a fluidized bed pyrolyzer and a fixed bed catalytic reactor was experimentally evaluated. The effect of weight hourly space velocity was investigated in the range of 0.35-0.77 h-1 during 260 min of operation. A lower biomass feed rate over a fixed amount of catalyst results in a higher degree of vapor deoxygenation (from 71 to 79.5 wt%) as well as higher concentrations of aromatic hydrocarbons. The carbon conversion from biomass to upgraded liquids is negatively correlated with the aromatic concentrations. Online gas analysis present no significant changes in the catalytic performance during the operational time. The results of this study indicate that the difference in liquid deoxygenation observed when varying the biomass feed rate is dependent on the vapor concentration in the gas stream over the catalytic bed rather than being significantly affected by catalyst deactivation during operation.