In this work, the catalytic deoxygenation of waste cooking oil (WCO) over acid–base bifunctional catalysts (NiLa, NiCe, NiFe, NiMn, NiZn, and NiW) supported on activated carbon (AC) was investigated. A high hydrocarbon yield above 60% with lower oxygenated species was found in the liquid product, with the product being selective toward n-(C₁₅ + C₁₇)-diesel fractions. The predominance of n-(C₁₅ + C₁₇) hydrocarbons with the concurrent production of CO and CO₂, indicated that the deoxygenation pathway proceeded via decarbonylation and decarboxylation mechanisms. High deoxygenation activity with better n-(C₁₅ + C₁₇) selectivity over NiLa/AC exposed the great synergistic interaction between La and Ni, and the compatibility of the acid–base sites increased the removal of oxygenated species. The effect of La on the deoxygenation reaction performance was investigated and it was found that a high percentage of La species would be beneficial for the removal of C–O bonded species. The optimum deoxygenation activity of 88% hydrocarbon yield with 75% n-(C₁₅ + C₁₇) selectivity was obtained over 20% of La, which strongly evinced that La leads to a greater enhancement of the deoxygenation activity. The NiLa/AC reusability study showed consistent deoxygenation reactions with 80% hydrocarbon yield and 60% n-(C₁₅ + C₁₇) hydrocarbon selectivity within 6 runs.

In Asian countries, the primary palm oil producers, used cooking oil (UCO) is the primary feedstock for biodiesel production. It can be converted into an eco-fuel for application in heavy machinery and diesel engine vehicles due to its low carbon emissions and low global warming potential. However, the illegal dumping of UCO containing triglyceride into flowing water bodies (resulting in wastewater treatment and purification complications) has prompted the design of smart UCO collection systems. This study aims to investigate the heterogeneous catalytic performance of biochar as a support catalyst derived from woodchips calcined at 400 °C and 800 °C under nitrogen gas flow. The catalyst was synthesized through the wet impregnation method using two metal oxides (5 wt.%, nickel and molybdenum) via transesterification to enhance the biodiesel yield. High biodiesel yield was obtained through the controlled parameters: 65–95 °C temperature, 10:1 methanol to oil ratio, and 2 h reaction time. The synthesized catalyst was characterized through X-ray Diffraction (XRD) and Field Emission Scanning Electron (FESEM). The biodiesel production was confirmed by Fourier Transform Infra-Red (FTIR) Spectroscopy. The results showed that the highest biodiesel yield was produced by the catalyst calcined at 800 °C, which shows a consistent trend in the yields obtained at temperatures in the order 75–85–95–65 °C. In conclusion, calcination at 800 °C resulted in a higher yield (74.66%) and catalyst reusability (≥5 cycles).

Waste cooking oil (WCO) from palm oil is one of the most prospective biodiesel feedstock when compared to other oil seeds. Thus, WCO has great potential as a green source of diesel fuel for engines in motor vehicles and machinery. This project aimed to study the potential of three randomly selected types of WCO, namely; sample A (used 1× once to fry an egg), sample B (used 3–5× to fry salted fish), and sample C (used repeatedly to fry banana fritter) for the production of green diesel fuel over Ni-Mo/AC (nickel and molybdenum oxides incorporated with activated carbon) catalyst through the deoxygenation (DO) process. The prepared catalyst was characterized through X-ray diffraction (XRD), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). The DO process was performed at 350 °C to remove oxygen from the WCO samples. The liquid products were analysed by gas chromatography-mass spectrometer (GC-MS) and gas chromatography-flame ionization detector (GC-FID), to measure the yields of straight-chain hydrocarbons and fractions in the range C₈‒C₂₀. Results showed that the highest n-(C₈‒C₂₀) hydrocarbon fractions were produced in the order of sample B (89.93%) > C (88.84%) > A (82.81%).

CO₂ capture on NiO supported imidazolium-based ionic liquid, NiO/[emim][HSO₄]/SiO₂ as an adsorbent was investigated using gas adsorption analyzer and physicochemical properties of the adsorbent were characterized using X-ray powder diffraction (XRD), surface area analyzer (BET method) and temperature-program-desorption analysis (TPD). Immobilization of ionic liquid on silica, [emim][HSO₄]/SiO₂ slightly decreased the surface area compared to bare silica from 266 to 256 m²/g due to the pore blocking by the confinement of IL in SiO₂ pore. Interestingly, introduction of NiO on supported ionic liquid, NiO/[emim][HSO₄]/SiO₂ was increased the surface area as well as pore volume from 256 to 356 m²/g and 0.14 to 0.38 cm³/g, respectively. The enhancement of surface area and pore volume was significantly increased the CO₂ adsorption performance with capacity of 48.8 mg CO₂/g adsorbent compared to [emim][HSO₄]/SiO₂ 27.3 mg CO₂/g adsorbent).