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A visible-light active N,S-codoped TiO2 incorporated with carbon nanotubes (CNTs) was synthesized by a multicomponent heterojunction scheme. The synthesized photocatalysts was examined by several analysis techniques. The conventional TiO2, N-doped TiO2, TiO2/CNT and N,S-codoped TiO2 were also synthesized, characterized, and integrated adsorptive-photocatalytic degradation rates were subsequently compared and assessed, for comparative purposes as reference photocatalysts. The parametric study was also carried out to investigate the effect of various operational factors, such as solution pH, the photocatalyst loading and initial concentration of dye solution, on the adsorptive-photocatalytic performance. The best activity performance was attained with the N,S-TiO2/CNTs nanocomposite due to the synergistic effect of ternary components caused by the incorporation of dopants and CNTs in TiO2 lattice, providing a high number of adsorption sites and facilitating the effective separation of photogenerated charge carriers and minimal recombination rates. N,S-TiO2/CNTs exhibited around three times higher photocatalytic performance than that of the binary composites, i.e., N-TiO2, TiO2/CNTs, N,S-TiO2, and about four times higher than the conventional TiO2. Furthermore, the superior nanocomposites were also investigated for their recyclability for five consecutive cycles.

The effect of catalyst structure, acidity, and Ga addition of zeolites on the pyrolysis of polypropylene (PP) was investigated by comparing PP cracking efficiency and product distribution properties in this study. Thermogravimetric analysis result indicated that HY(SiO2/Al2O3; 30) is the most effective catalyst lowering PP decomposition temperature, followed by Ga/HZSM-5(30), HZSM-5(30), HZSM-5(80), and HZSM-5(280). Meanwhile, Ga/HZSM-5(30) revealed the lowest apparent activation energy (Ea), 110 kJ/mol, than HY(30) (159 kJ/mol), and other HZSM-5 catalysts (122 ~ 172 kJ/mol), suggesting its high efficiency lowering Ea on PP pyrolysis. Py-GC/MS results also suggested that Ga/HZSM-5 produces the largest amount of aromatic hydrocarbons, followed by HZSM-5(30), HZSM-5(80), HY(30), and HZSM-5(280). The increase of Ga/HZSM-5(30) amount on PP pyrolysis led the further decrease of Ea value and increase of aromatics production efficiency.

Oxidative desulfurization (ODS) is a swiftly rising organosulfur compounds eradicating system, effective enough at a mild temperature and pressure, overwhelming the necessity of costly hydrogen in the traditional HDS systems. In this study, pure LaVO4 photocatalyst was prepared using the hydrothermal approach and employed for deep oxidative desulfurization application in the aerobic environment under visible-light irradiations. The as-prepared photocatalyst semiconductor material was characterized by FTIR, SEM, UV–vis DRS and Raman analyses. The examined photocatalyst presented a narrow bandgap, a small particle size, high photo-responsive monoclinic phase, high light photons capturability, plenteous active sites accessibility and reduced recombination of photogenerated charge carriers, ensuing a good visible-light-driven deep oxidative desulfurization ability. The photocatalytic material was tested for its performance over different petroleum refinery diesel pool fraction streams including hydrodesulfurization unit diesel rundown, mild hydrocracking unit rundown gas oil, heavy kerosene oil and the ultimate diesel oil blend, containing organosulfur compounds ranging from disulfides to the stringent organosulfur compounds, with the quantity lying between 57 and 863 ppm. The kinetic study was found in agreement with the pseudo-first-order kinetics. The conceivable desulfurization mechanism was also anticipated. Moreover, the recyclability of the photocatalytic material was also discussed.

Steam-gasification of linear low-density polyethylene (LLDPE) waste to hydrogen-rich gas has been studied systematically over nickel (10 wt.%) loaded on a variety of supports (Al2O3, CeO2, and CeO2-ZrO2) synthesized using a novel solvent deficient method (SDM). The hydrogen selectivity order of the catalysts was reported as Ni/CeO2-ZrO2>Ni/CeO2>Ni/Al2O3. The highest catalytic H2 selectivity of the Ni/CeO2-ZrO2 catalyst was reported to be ∼76 vol.%, and was attributed to the smaller nickel crystals that were finely dispersed on the support, and to formation of Ce1-xZrxO2-δ solid solutions. The Ce1-xZrxO2-δ solid solution in the Ni/CeO2-ZrO2 catalyst was observed to be bi-functional, thus reflecting the acceleration of the water gas shift and the oxidation of carbon to CO and CO2. The better resistance of the Ni/CeO2-ZrO2 catalyst towards coke deposition also indicated its potential for commercial-scale applications for the steam gasification of plastics. Therefore, this research provides an advanced route to recycle LLDPE plastic waste into hydrogen fuel, which presents both economical and environmental benefits.

In this study, conversion of n-propanal to produce 2-methyl-2-pentenal (C6 compound, a fuel range precursor) was carried out using AMW-SBA-15 catalyst synthesized from activated marble waste (AMW) consisting mainly of Ca2+ and Mg2+ ions. AMW-SBA-15 catalysts with different weight ratios of AMW/Si (6, 12, and 18 wt. %) were prepared using single step sol-gel method. The catalytic activities were examined using a fixed bed continuous reactor over temperature ranging from 350−425 °C under atmospheric pressure. The 12AMW-SBA-15 catalysts showed superior catalytic performance with n-propanal conversion of 75 % and C-6 compound selectivity of 81 % at 375 °C without the need of deactivation for 12 h. To elucidate the structure-activity relationship, all catalysts were characterized using a variety of techniques. The superior performance of 12AMW-SBA-15 was ascribed to the high surface area and smaller particle size as well as the high hydrophobicity, which controlled the hydration of Ca2+/Mg2+ ions during the reaction.