Luqman Buchori

The renewable energy transition demands efficient energy storage, where lithium-ion batteries (LiBs) are crucial for battery energy storage systems (BESS). This study reports the hydrothermal synthesis and characterization of nitrogen-doped graphene (NDG) from puspa wood biomass for anode applications. Puspa wood contains approximately 43.98% carbon with a low ash content of 1.256%, indicating its suitability as a carbon precursor. Through carbonization and graphitization, amorphous carbon was successfully transformed into an ordered graphite structure, as confirmed by the disappearance of –OH groups (3400–3600 cm−1) in Fourier-transform infrared (FTIR) spectra and by X-ray diffraction (XRD) peak shifts from 23.50° to 26.50°. Subsequent oxidation produced graphene oxide (GO) characterized by carbonyl (C=O) groups at 1704 cm−1, while nitrogen doping introduced C–N (1200 cm−1) bonds, resulting in the formation of NDG. Nitrogen doping is known to enhance electrochemical properties. These findings highlight puspa wood as a promising precursor for NDG synthesis and provide a foundational material characterization that supports its further electrochemical investigation. This study demonstrates the promise of puspa wood biomass as a sustainable carbon source for advanced anode materials, contributing to eco-friendly battery technology.

Biodiesel is one of the products resulting from the initiation of energy diversification which can overcome the energy crisis both in Indonesia and in the world. Biodiesel can reduce combustion emissions. The purpose of this study was to produce biodiesel from waste cooking oil (WCO). The study was conducted using the simultaneous esterification-transesterification method with the help of a catalyst. The catalyst used was a bifunctional catalyst, namely CaO/Fe2O3. Waste cooking oil raw materials and biodiesel products were analyzed by GC-MS, while the catalyst was analyzed by SEM-EDX and XRD. The catalyst calcination temperature was varied at 750-950°C and the esterification-transesterification reaction time was varied at 1-5 hours. The results of the study showed that the highest biodiesel yield was obtained at 82% at a catalyst calcination temperature of 800°C and a reaction time of 4 hours. The methyl ester composition formed was 97.61%. The research results show that the biodiesel products produced comply with SNI 7182-2015 standards. This finding proves that waste cooking oil can be used as a raw material for biodiesel so that it will reduce the impact of environmental pollution.

Biodiesel is a renewable liquid fuel that can be produced through the transesterification reaction of biomass. The objective of this research was to examine the effect of comparative composition of CaO and Fe2O3 on CaO/Fe2O3 catalysts from eggshells and Fe2O3 in the production of biodiesel from waste cooking oil. In addition, it was also studied the effect of the ratio of oil and methanol on the yield and characteristics of the biodiesel produced. Catalysts were prepared through impregnation. The esterification-transesterification process was carried out with the conditions WCO:methanol molar ratio of 1:3, 1:6, 1:9, 1:12 and 1:15, catalyst (3%wt oil), heated at 65°C for 3 hours with a stirring scale of 1200 rpm. The results showed biodiesel production using CaO: Fe2O3 catalyst with the ratio of CaO: Fe2O3 70:30 and WCO:methanol molar ratio of 1:9 obtained higher yield (84.5%) compared to others. The best biodiesel yield produced is the CaO:Fe2O3 catalyst ratio of 70:30 and the WCO:methanol molar ratio of 1:9 with a biodiesel yield of 84.50% with a methyl ester content of 99.63% and a FAME yield of 84.14%. The biodiesel produced has met the requirements of the Indonesian National Standard (SNI) in terms of density and viscosity.

Kaolin is a natural ingredient that is in abundance and has not been widely used. Kaolin is a source of silica (SiO2) and alumina (Al2O3) so that it can be used as a heterogeneous catalyst in biodiesel production. This research aims to examine the influence of using impregnated kaolin as a heterogeneous catalyst on production of biodiesel. Research methods include calcination of natural kaolin, impregnation of kaolin using KI, KIO3, and preparation of kaolin-methoxide in various concentrations, as well as biodiesel production using an impregnated kaolin catalyst. The catalyst was characterized using XRD and SEM. The catalyst was tested for basicity using the Hammet indicator method with acid-base titration. The biodiesel product obtained was analyzed using GCMS. The results of XRD analysis showed that 8% kaolin-methoxide catalyst had the highest crystallinity among the others. The crystallinity obtained was 87.84% with a composition of 15.79% SiO2 and 78.86% Al2O3. SEM image results also show a more visible crystal shape. The highest basicity of the catalyst obtained was 0.240 mmol. The highest biodiesel yield using 8% kaolin-methoxide catalyst is 99.48%.

Energy demand will increase along with the increase in population. The current energy demand is dominated by non-renewable energy as it could reduce dependence on fossil energy sources; hence, it is imperative to be developed. Biodiesel with waste cooking oil as its raw material is one of the renewable energies currently being developed. Catalyst can be utilized to improve the quality of biodiesel product and process. The major content in solid waste of geothermal power plant is silica oxide, while dolomite contains magnesium oxide and calcium oxide. This study aims to test the MgO-CaO/SiO2 catalyst performance from geothermal waste and dolomite in biodiesel production. The results of catalyst characterization based on FTIR, SEM, and BET tests indicates a successful impregnation method in MgO-CaO/SiO2 catalyst production. The result shows that the best variable to produce biodiesel is at the ratio of MgO-CaO: SiO2 is 15:85. The conversion of biodiesel using this variable is 92.63%. The overall results of biodiesel obtained in this study have a good quality and is in accordance with SNI 7182-2015.

Energy consumption in the transportation sector steadily rises each year, requiring an effective solution to meet the demands present. In this study, biokerosene was produced through the hydrocracking process using NiMo-Al₂O₃ as a catalyst and dirty palm oil as raw material. The synthesised catalyst was characterised by scanning electron microscopy (SEM) and X-ray diffraction (XRD), while the biofuel product which was analysed by gas chromatography-mass spectrometry (GCMS). The results showed that in the hydrocracking process, the decarboxylation and decarbonylation reactions were the dominant pathways. The conversion of biokerosene increased with increasing catalyst concentration, temperature and reaction time. The highest biokerosene yield was found to be 56.38% with a catalyst concentration of 0.01 g-catalyst/g-oil, 3 h reaction time and 450°C reaction temperature. The optimum catalyst concentration was 0.04 g-catalyst/g-oil, while the optimum temperature was 550°C and the optimum reaction time was 3 h.

The synthesis of biodiesel from the used cooking oil with CaO catalyst from waste animal bones has been investigated. The content of free fatty acids (FFA) in the used cooking oil was reduced by adsorption using activated charcoal from a salak peel. Biodiesel synthesis was carried out via transesterification using CaO catalyst. The CaO catalyst was obtained from waste animal bones calcined in the Ney Vulcan furnace. The effect of calcination temperature was studied in the range of 873‒1273 K. The effect of catalyst loading was investigated by varying within the range of 1‒9 wt %. The methanol to oil molar ratio was investigated in the range from 6:1 to 18:1. The effect of the transesterification reaction time was studied with a time variation of 1‒5 h. The optimum operating conditions were determined. Under these conditions, the yield of biodiesel produced was 97.56 % with an ester content of 96.06 %. It was shown that the physicochemical properties of biodiesel produced meet the standards.

The design of this research consisted of four stages, that is manufacture of catalysts, cellulose hydrolysis process, glucose yield test and optimization process.The research data is plotted in a mathematical model that is optimized using software of Statistica 10 with Response Surface Methodology (RSM) and ANOVA methods. From the RSM method was obtained mathematical equation model for the relationship of the combination of temperature, time and amount of catalyst to glucose levels, that is: Y = -20, 0457 + 5,341x₁ -3, 245 x 2 1 + 6, 471x₂ -2,798 x 2 2 +4,697x₃ -2,965x² ₃ +1,241x₁x₂ -0,996x₁x₃ +0,675 x 2 3 . ANOVA method produces a value of determination coefficient (R²) as big 0.91545. In this research, the optimum temperature is at 70°C, the optimum time is at 2 hours, and the optimum amount of catalyst is at 11 grams. The results of glucose yield obtained from the optimal operating conditions is 31%.

Styrene is an organic compound used for the synthesis of polymers, co-polymers, and rubber. Generally, the reaction to form styrene comes from the dehydrogenation of ethylbenzene. This reaction occurs when the compound is in the vapor phase and is endothermic. One of the technologies for ethylbenzene dehydrogenation is Lummus/UOP Smart SM. This technology uses oxygen to heat the reaction and makes the hydrogen disappear, so the reacting reaches the highest ethylbenzene conversion. The focus of this research was pinch analysis on Lummus/UOP Smart SM. The first step in pinch analysis is data extraction. An alternative is to perform pinch analysis with a composite curve, problem table, shifted composite curve, and grand composite curve. Then is continued to create a design Heat Exchanger Network (HEN). The application of pinch analysis to evaluate heating duty, cooling duty, Maximum Energy Recovery (MER), and determine the exact HEN for optimal energy. In this research, the integration of the process showed not optimal results, especially in cooling duty, because the energy recovery was obtained small, and for heating duty saved about 14%.

The production of biodiesel using zeolite catalysts from geothermal solid waste has been studied. This study aims to make zeolite catalysts as catalysts in biodiesel production, assessing the effect of catalyst concentration, and temperature in the esterification–transesterification process on the biodiesel yield produced. The results showed that the synthesized zeolite catalyst was an analcime zeolite catalyst (Al_1.9Na_1.86O₁₂Si₄). The biodiesel yield of 98.299% with 100% fatty acid alkyl ester (FAAE) content was achieved at a catalyst concentration of 5%wt and a reaction temperature of 300 °C for one-hour reaction time. The yield of biodiesel decreased with repeated catalysts, which experienced morphological changes before and after three usage times. Consequently, in this case, the catalyst cannot be regenerated.