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The objective of this research was to prepare low-cost catalyst for green diesel conversion from vegetable oil. The catalyst of nickel-dispersed biochar (Ni/BC) was prepared by direct pyrolysis of nickel precursor with palm leaves waste under N2 stream at 500 °C. The obtained catalyst was examined by using x-ray diffraction, scanning electron microscope-energy dispersive x-ray, transmission electron microscopy, gas sorption analysis, FTIR and surface acidity examination. The catalytic activity testing was performed on rice bran oil hydrodeoxygenation at varied temperature and time of reaction. Based on analyses, the results showed the successful preparation of Ni/BC with the characteristic of single nickel nanoparticles decorated on surface. The increasing specific surface area of material was conclusively remarked the surface area enhancement by nickel dispersion along with the increased surface acidity, suggesting that the material can be applied for acid catalysis applications. The Ni/BC exhibited excellent catalytic conversion of rice bran oil with the high selectivity toward diesel fraction with 85.3% yield and 92.6% selectivity. Copyright © 2023 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

The concern associated with the depletion of fossil fuel energy has opened up windows of opportunity for researchers to develop potential energy from renewable resources. The renewable green diesel with diesel range hydrocarbon structure has gained increasing popularity by removing oxygen molecule via direct or hydrodeoxygenation (HDO) and indirect or deoxygenation (DO) reaction. The catalyst design is an important key to achieve the high quality of diesel range hydrocarbon fuels. The different catalyst properties effect to the distribution of deoxygenated liquid product, the catalytic activity and coke formation during the reaction process. The interaction between metal and support catalyst causes electron transfer to give the synestistic effect. The acidity and basicity play important role in C-C and C-O breaking bond in triglyceride and prevent the coke formation. The pore structure and pore size catalyst provide the accessibility of active sites alleviates the diffusion limitation of reactants/ products.

Hydrodeoxygenation (HDO) is applied in fuel processing technology to convert bio-oils to green diesel with metal-based catalysts. The major challenges to this process are feedstock, catalyst preparation, and the production of oxygen-free diesel fuel. In this study, we aimed to synthesize Ni catalysts supported on silica-zirconia and alumina-zirconia binary oxides and evaluated their catalytic activity for waste cooking oil (WCO) hydrodeoxygenation to green diesel. Ni/Al2O3-ZrO2 and Ni/SiO2-ZrO2 were synthesized by wet-impregnation and hydrodeoxygenation of WCO was done using a modified batch reactor. The catalysts were characterized using X-ray diffraction (XRD), X-ray fluorescence (XRF), and scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDS), and N2 isotherm adsorption-desorption analysis. Gas chromatography - mass spectrometry (GC-MS) analysis showed the formation of hydrocarbon framework n-C15 generated from the use of Ni/Al2O3-ZrO2 with the selectivity of 68.97% after a 2 h reaction. Prolonged reaction into 4 h, decreased the selectivity to 58.69%. Ni/SiO2-ZrO2 catalyst at 2 h showed selectivity of 55.39% to n-C15. Conversely, it was observed that the reaction for 4 h increased selectivity to 65.13%. Overall, Ni/Al2O3-ZrO2 and Ni/SiO2-ZrO2 catalysts produced oxygen-free green diesel range (n-C14-C18) enriched with n-C15 hydrocarbon. Reaction time influenced the selectivity to n-C15 hydrocarbon. Both catalysts showed promising hydrodeoxygenation activity via the hydrodecarboxylation pathway. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Because of the significant demand for fuels in the transportation sector in Indonesia, as well as concerns about energy security and global warming, renewable, sustainable, and alternative energy sources such as biofuels are required to replace petroleum-based fuels. Promoting the production of green diesel from crude palm oil (CPO) using palm fatty acid distillate (PFAD) as its byproduct will make the overall process more efficient and environmentally friendly in Indonesia. As a result, CPO-based diesel production will be a green and high-value sector. By replacing fossil diesel with green diesel, a sustainable energy source can be assured without further depleting current fossil fuels, leading to cleaner and greener energy in the future and meeting the net-zero aim by 2060.

The Petroleum diesel-based fossil fuel remains the primary source of energy consumption in Indonesia. The utilization of this unrenewable fuel depletes fossil fuels; thus, an alternative, renewable fuel, such as one based on biohydrocarbon from biomass-green diesel-could be an option. In this work, green diesel was produced through the hydrodeoxygenation from palm oil and processed in a batch-stirred autoclave reactor over natural zeolite (NZ) and NZ modified with 3 wt.% Fe metal (Fe/NZ) as heterogeneous catalyst. NZ showed high crystallinity and suitability to the simulated pattern of the mordenite and clinoptilolite phases according to X-ray diffraction (XRD) analysis. The presence of Fe metal was further confirmed by XRD, with an additional small diffraction peak of Fe0 that appeared at 2θ = 44-45°. Meanwhile, NZ and Fe/NZ were also characterized by Scanning electron microscopy (SEM) with Energy Dispersive X-ray (EDX), X-ray Fluorescence (XRF), and Surface Area Analyzer (SAA). The obtained materials were tested for the conversion of palm oil into diesel-range hydrocarbons (C15-C18) under conditions of 375 °C and 12 bar H2 for 2 h. NZ and Fe/NZ produced a liquid hydrocarbon with straight-chain (C15-C18) alkanes as the most abundant products. Based on Gas Chromatography-Mass Spectrometry (GC-MS) measurement, a higher conversion of palm oil into diesel-like hydrocarbons reached more than 58% and 89%, when NZ and Fe modified NZ (Fe/NZ), respectively were used as catalysts.