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Solar thermo-photocatalytic methanation using a bifunctional RuO2:TiO2/Z13X photocatalyst/adsorbent material for efficient CO2 capture and conversion

Publication . Paulista, Larissa O.; Ferreira, Alexandre F.P.; Rodrigues, Alírio; Martins, Ramiro; Boaventura, Rui; Vilar, Vítor J.P.; Silva, Tânia F.C.V.

A novel bifunctional photocatalyst/adsorbent material based on the RuO2:TiO2/zeolite 13X (Z13X) composite was developed to enhance solar-driven methanation through simultaneous carbon dioxide (CO2) capture and thermo-photoconversion. The activity/stability of the hybrid material towards methane (CH4) production was assessed by varying the (i) photocatalyst composition (Ru load and semiconductor type), (ii) bifunctional material composition (photocatalyst-to-zeolite ratio) and impregnation method, (iii) illumination source and power (simulated sunlight and UVA/Visible LEDs), (iv) temperature, and (v) catalyst reuse. Additionally, adsorption equilibrium isotherms were determined to characterize the adsorption ability of the bifunctional material for both CO2 and CH4 gases. The hybrid RuO2(4.0%):TiO2(26.3%)/Z13X material (30 mg), synthesised by the solid-state impregnation method, showed the best results under simulated sunlight (0.75 W) at 150 ºC, achieving a 88% CO2 thermo-photoreduction after 100 min, corresponding to a specific CH4 production of 29.2 mmol gactive_cat−1 h−1 (309 mmol gRu−1 h−1) and apparent quantum yield of 20.7%. In adsorption equilibrium isotherms, the bifunctional material's adsorption was about 2.6-fold higher than the photocatalyst at 150 ºC, suggesting that enhanced methanation performance can be attributed to the synergistic action of CO2 capture and thermo-photoconversion.

2024Journal article

Open access

A novel ceramic tubular membrane coated with a continuous graphene-TiO2 nanocomposite thin-film for CECs mitigation

Publication . Presumido, Pedro Henrique; Santos, Lucrécio F. dos; Neuparth, Teresa; Santos, Miguel M.; Feliciano, Manuel; Primo, Ana; Garcia, Hermenegildo; B- Đolić, Maja; Vilar, Vítor J.P.

This work presents a ceramic tubular membrane coated with a continuous graphene-TiO2 nanocomposite thinfilm for contaminants of emerging concern (CECs) removal from synthetic and real matrices in single-pass flow-through operation. Microfiltration ceramic membranes were coated in situ with graphene (G)-TiO2-P25 nano-composite using two different methods: Membrane type A - TiO2-P25 incorporated in the G preparation stage (1% [MA-1], 2% [MA-2] and 3% [MA-3] [w/v]), and Membrane type B - TiO2-P25 thin-film uniformly coated over the G film surface (coating layers: 3 [MB-1], 6 [MB-2], and 9 [MB-3]). After the catalyst deposition and before the pyrolysis step, air was forced to pass through the membranes pores (inside-outside mode), providing a porous film. The CECs solution (diclofenac-DCF, 17β-estradiol-E2, 17α-ethinylestradiol-EE2 and amoxicillin-AMX) was prepared using Ultrapure water (UPW) or an urban wastewater after secondary treatment (UWW) fortified with 500 μg L􀀀 1 of each CEC. Membranes were characterized by the following techniques: Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier-Transform Infrared spectroscopy (FTIR), Diffuse Reflectance UV-Visible spectroscopy (DR UV-Vis) and Raman spectroscopy. The membranes coated with MA-3 and MB-2 catalyst films, irradiated by UVA light, showed the highest ability for CECs removal. Furthermore, the Relative flux reduction ratio (RFR) decreased around 45% in the absence of UVA light, owing to membrane fouling. The combination of filtration and oxidation (G-TiO2-UVA) provided a permeate with higher quality and minimized membrane fouling. Although membrane type B allowed for a permeate with higher quality, membrane type A provided a higher permeate flux.

2022Journal article

Open access