Controlled Synthesis of Titania using Water-soluble Titanium Complexes: A Review

The development of human society has led to the increase in energy and resources consumption as well as the arising problems of environmental damage and the toxicity to the human health. The development of novel synthesis method which tolerates utilization of toxic solvents and chemicals would fulfill the demand of the society for safer, softer, and environmental friendly technologies. For the past decades, a remarkable progress has been attained in the development of new water-soluble titanium complexes (WSTC) and their use for the synthesis of nanocrystalline titanium dioxide materials by aqueous solution-based approaches. The progress of synthesis of nanocrystalline titanium dioxide using such WSTCs is reviewed in this work. The key structural features responsible for the successfully controlled synthesis of TiO2 are discussed to provide guidelines for the morphology-controlled synthesis. Finally, this review ends with a summary and some perspectives on the challenges as well as new directions in this fascinating research

Catalytic Performance of La-Ni/Al2O3 Catalyst for CO2 Reforming of Ethanol

Bio-derived ethanol has been considered as an attractive and alternative feedstock for dry or steam reforming reactions to generate renewable hydrogen, which may be used for replacement of conventional fossil fuels. Ethanol dry reforming (EDR) is an environmentally-friendly process since it transforms greenhouse gas, CO2 to value-added products and ethanol can be easily obtained from biomass which is free of catalyst poisons (i.e. sulphur-containing compounds). However, there are currently limited studies regarding syngas production from EDR [1, 2]. Ni-based catalysts are commonly used for reforming reactions due to its capability of C-C bond rupture, relatively low cost and high availability compared to precious metals [2]. Nevertheless, carbonaceous deposition may considerably deteriorate catalytic activity and stability of Ni-based catalysts. La promoter reportedly hindered carbon deposition and improved catalytic activity [3]. Hence, the objective of this research was to investigate the effect of La promotion on 10%Ni/Al2O3 catalyst for EDR

Carbon Dioxide Dry Reforming of Glycerol for Hydrogen Production using Ni/ZrO2 and Ni/CaO as Catalysts

Glycerol, byproduct from the biodiesel production can be effectively utilized as the promising source of synthesis gas (syngas) through a dry reforming reaction. Combination of these waste materials with greenhouse gases which is carbon dioxide (CO2) will help to reduce environmental problem such as global warming. This dry reforming reaction has been carried out in a fixed bed batch reactor at 700 °C under the atmospheric pressure for 3 hours. In this experiment, reforming reaction was carried out using Nickel (Ni) as based catalyst and supported with zirconium (ZrO2) and calcium (CaO) oxides. The catalysts were prepared by wet impregnation method and characterized using Bruanaer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Thermo Gravimetric (TGA), and Temperature Programmed Reduction (TPR) analysis. Reaction studies show that 15% Ni/CaO give the highest hydrogen yield and glycerol conversion that peaked at 24.59% and 30.32%, respectively. This result is verified by XRD analysis where this catalyst shows low crystallinity and fine dispersion of Ni species resulted in high specific surface area which gives 44.93 m2/g that is validated by BET. 

Construction of dual Z-scheme g-C3N4/Bi4Ti3O12/Bi4O5I2 heterojunction for visible and solar powered coupled photocatalytic antibiotic degradation and hydrogen production: Boosting via I−/I3− and Bi3+/Bi5+ redox mediators

© 2020 Elsevier B.V. Inspired by waste to energy production, we report construction of dual Z-scheme advanced photocatalyst g-C3N4/Bi4Ti3O12/Bi4O5I2 heterojunction for coupled photocatalytic H2 evolution and degradation of antibiotics with high efficiency. The optimal CTBT-30 i.e (40 %g-C3N4/Bi4Ti3O12)/30 % Bi4O5I2 photocatalyst exhibited an excellent rate of H2 production under visible light (56.2 mmol g−1 h−1) along with simultaneous 87.1 % ofloxacin (OFL) removal. The H2 production rate is manifolds higher than in ultrapure water, sulfadiazine, rhodamine B and higher in hole scavenging triethanolamine. The interfacial intimate coupling with well-matched energy bands, foster the charge separation with effective Z-scheme transfer facilitated by I3−/I− and Bi3+/Bi5+ and redox mediators. The scavenging of majority of holes for direct oxidation or via [rad]OH radical formation leaves photogenerated electrons (at CB of g-C3N4 and Bi4O5I2) free for H2 evolution from H2O. Such work is promising for designing high photo-absorbing heterojunction photocatalysts for dual functionalities of clean energy production and environmental detoxification

Silicate glass matrix@Cu\u3csub\u3e2\u3c/sub\u3eO/Cu\u3csub\u3e2\u3c/sub\u3eV\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e p-n heterojunction for enhanced visible light photo-degradation of sulfamethoxazole: High charge separation and interfacial transfer

© 2020 Elsevier B.V. Focusing on the treatment of pharmaceuticals contaminated water by advanced oxidation processes, a novel three dimensional silicate glass matrix (3-DG) coupled Cu2O/Cu2V2O7 p-n heterojunction was constructed by in-situ hydrothermal technique. The optimal Cu2O/Cu2V2O7 with 30 wt % Cu2V2O7 (CV-30) degrades 90.1 % sulfamethoxazole (SMX) in 60 min and nearly 100 % removal in 45 min via coupling with 3-DG. Under natural sunlight ∼ 80 % SMX removal was observed. The internal electric field of the p-n junction facilitates the electron flow via the interface. 3-D silicate glass increases the visible light absorption dramatically via internal reflection which facilitates higher exposure for the junction and shortens the diffusion length of charge carriers. The effect of reaction parameters suggests that HCO3− and CO32− ions substantially escalate the SMX removal rate. Scavenging experiments and ESR probe suggest [rad]O2− as the main active species followed by [rad]OH radicals. The degradation products were detected by LC–MS analysis and a degradation mechanism was also predicted. The photocatalytic mechanism was explained in terms of the electron transfer facilitated by conventional transfer and Z-scheme. This strategy to construct such highly visible and solar active p-n heterojunctions will pave way for future opportunities for the degradation of recalcitrant pharmaceutical pollutants

Chapter 11 - Sequestration of carbon dioxide into petroleum reservoir for enhanced oil and gas recovery

This chapter presents a detailed and important study of the effectiveness of enhanced oil/gas technology in an unconventional petroleum reservoir. To meet the challenges of ever-increasing amount of greenhouse gas emissions and the long-term need for energy supplies, enhanced oil/gas recovery (EOR/EGR) techniques, which are the most appropriate approach to be used for both scientific and industrial benefits, are systematically explored. Owing to the decline of fossil energy, the global demand for energy could not be fulfilled by oil and natural gas. Generally, EOR/EGR is used to maintain critically regulated pore strength where gases (e.g., CO2, CO, N2, etc.) are injected into the petroleum reservoir through a vertical well. These techniques for oil recovery are more efficient, while primary and secondary techniques for oil recovery are inconvenient. The use of CO2 storage or EOR/EGR in oil or gas reserves is more complicated due to their significant variations in porosity and permeability. This chapter concludes with an important debate on the prospects and problems of CO2 sequestration in oil and gas reservoirs for EOR/EGR and future avenues for study

Hydrogen-rich Syngas Production from Ethanol Dry Reforming on La-doped Ni/Al2O3 Catalysts: Effect of Promoter Loading

Ethanol dry reforming has been studied over La-promoted Ni catalysts supported on Al2O3 with different promoter loadings at varying CO2 partial pressure of 20-50 kPa. Catalysts were prepared via co-impregnation technique and characterized using BET surface area, X-ray diffraction measurement, temperature-programmed calcination and scanning electron microscopy. Doped and undoped catalysts possessed high surface area of about 86-108 m2 g-1 and La promoter was well-dispersed on support surface. Xray diffraction measurements indicated the formation of La2O3, NiO and NiAl2O4 phases in line with temperature-programmed calcination results. La-addition enhanced the dispersion of NiO particles and reduced the agglomeration of metal oxides. Both C2H5OH and CO2 conversions improved with increasing CO2 partial pressure rationally due to the growing secondary CO2 reforming of CH4 reaction. The ratio of H2/CO produced from ethanol dry reforming varied from 1.1 to 1.4 favored for usage as feedstocks of Fischer-Tropsch synthesis. The yield of H2 and CO also enhanced with increasing CO2 partial pressure whilst the optimal La loading in terms of C2H5OH conversion was observed at 3%La and catalytic activity increased with promoter addition reasonably owing to the redox properties of La promoter. CO2 reforming of ethanol reaction appeared via ethanol decomposition to CH4 intermediate product, which was subsequently converted to CO and H2 mixture through CH4 dry reforming reaction