• Energy Research

Abstract Catalytic ethanol steam reforming (ESR) offers a sustainable and attractive route for hydrogen production, which can be utilized as a substitute for fossil fuels. ESR for hydrogen production involves complex reactions and yield of hydrogen depends upon several process variables such as temperature, molar feed ratio and pressure. In this study, a thermodynamics analysis coupled with experimentation for ESR toward hydrogen production has been investigated. The structured montmorillonite (MMT) nanoclay and TiO2 supported catalyst incorporated by nickel (Ni) was developed via a sol-gel and impregnation methods. The catalyst samples were characterized by XRD, FE-SEM, EDX, BET and TGA to understand crystallinity, surface morphology, pore structure and stability. Initially, thermodynamic analysis was employed to study the effect of reaction conditions on equilibrium product distribution of ESR. The equilibrium concentrations of different compounds were calculated by the method of direct minimization of the Gibbs free energy. Optimum conditions for ESR were found to be; atmospheric pressure, temperatures between 600 and 700 °C and steam to ethanol (S/E) feed molar ratio of 10:1, at which highest hydrogen can be produced with minimum coke formation. Next, catalytic performance of NiO/MMT-TiO2 catalyst for enhanced ESR for hydrogen production was conducted in a tubular fixed bed reactor at 500 °C and atmospheric pressure. Noticeably, Ni-promoted TiO2 NPs found efficient for selective hydrogen production, yet MMT-supported Ni/TiO2 gave much higher ethanol conversion with improved hydrogen yield. Using 12% Ni-10% MMT/TiO2 catalyst, ethanol conversion of 89% with H2 selectivity and yield of 61 and 55%, respectively were obtained. The stability test revealed MMT-supported catalysts maintained activity even after 20 h. By comparing results, it was possible to explain deviations between thermodynamic analysis and experimental results regarding carbon deposition and selective hydrogen production.

Abstract Global environmental concern and the diminishing of fossil fuel escalated the seek for the development of renewable alternative fuels such as biodiesel. Biodiesel can be produced via transesterification and esterification reactions, expedited with a suitable homogeneous or heterogeneous catalyst. Heterogeneous catalyst offers high activity and high selectivity; and this is due to the chemical and physical properties of the catalyst. Heterogeneous catalyst can be produced from various sources such as metal oxides and its derivatives; and bio-wastes containing carbon sources which are heterogeneous in nature. Lately, the utilization of sulfonated carbon acid catalyst becomes increasingly attractive due to its advantages and potential to replace homogeneous and heterogeneous catalysts in the biodiesel manufacturing industry. The catalyst is environmentally benign and can effectively convert free fatty acid to alkyl ester. Sulfonated carbon acid catalyst can be prepared by incorporating sulfonation agent which contains sulfonic group into the carbonaceous material. The performance of sulfonated carbon acid catalyst is highly dependent on the treatment condition and its starting material. This review focuses on the recent invention and use of the sulfonic group bearing porous carbon heterogeneous catalysts for biodiesel production.

Response surface methodology (RSM) and multi-objective genetic algorithm was employed to optimize the process parameters for catalytic conversion of glycerol, a byproduct from biodiesel production, to light olefins using Cu/ZSM-5 catalyst. The effects of operating temperature, weight hourly space velocity (WHSV) and glycerol concentration on light olefins selectivity and yield were observed. Experimental results revealed the data adequately fitted into a second-order polynomial model. The linear temperature and quadratic WHSV terms gave significant effect on both responses. Optimization of both the responses indicated that temperature favouring high light olefin formation lied beyond the experimental design range. The trend in the temperature profile concurred commensurately with the thermodynamic analysis. Multi-objective genetic algorithm was performed to attain a single set of processing parameters that could produce both the highest light olefin selectivity and yield. The turn-over-frequency (TOF) of the optimized responses demonstrated a slightly higher value than the one which was not optimized. Combination of RSM, multi-objective response and thermodynamic is useful to determine the process optimal operating conditions for industrial applications.

The present work uses the total Gibbs free energy minimization approach to analyze the thermodynamic equilibrium analysis of bio-oil model compounds to light hydrocarbons. A mixture of model compounds was subjected to co-cracking with methanol and ethanol, and at a range of temperatures (300–1200 °C) and pressures (1–50 bars), the equilibrium compositions were calculated as a function of the hydroxypropanone-acetic acid-ethyl acetate/methanol ratio (HAEM) and the hydroxypropanone-acetic acid-ethyl acetate/ethanol ratio (HAEE). Possible reactions were analyzed, revealing that methane is the predominant product, followed by hydrogen, carbon monoxide, carbon dioxide, and propionic acid. The production of light hydrocarbons, including ethylene, ethane, propylene, and propane, was minimal. Notably, the co-reactant ethanol (HAEE 1:12) in the co-cracking of bio-oil model compounds demonstrated a significant effect on the production of methane, ethylene, and propylene at 1 bar pressure and 300 °C (for methane production) and 1200 °C (for ethylene and propylene production).

AbstractThermodynamic equilibrium analysis of glycerol steam reforming to light olefins has been investigated based on the total Gibbs free energy minimization method. Equilibrium product compositions for glycerol steam reforming were determined according to the following range: temperature, 573–1273K; GWR (glycerol/water ratio), 1:12 - 2:1 and pressure, 1-12 bars. Analysis of the feasible reactions revealed hydrogen as the main product followed by carbon monoxide, methane and ethane. The equilibrium analysis indicated light olefins formation was not spontaneous. The amount of ethylene produced was very small, but improved at higher pressure and temperature between 873-1023K. Coking was also dependent on GWR and temperature. From Gibbs analysis, light olefin formation at equilibrium is thermodynamically not feasible, but experimental work involving catalyst proved that ethylene selectivity could be improved in a heterogeneous reaction.

The use of dual acidity ionic liquids for direct hexose sugars conversions aims to increase the yields and selectivity of biofuel additive, ethyl levulinate production.

Abstract The depletion of fossil fuel and the distressing environmental condition originated from the massive consumption of nonrenewable energy has urge towards the seeking for a cleaner and renewable energy source. Numerous forms of renewable energy have been developed over the past few decades and biodiesel emerged as one of the prospective candidate. The demand for global biodiesel production has been steadily growing. In line with that, researches around the world are racing towards making biodiesel technology more sustainable and economically viable process. In this investigation, the development of biodiesel from palm fatty acid distillate via the esterification process using sulfonated chicken bone and cow bone catalyst assisted by microwave irradiation was conducted (replacing the conventional oven heating). Subsequently the bones were calcined at 900 °C and then sulfonated. The synthesized catalysts were characterized using X-Ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscope, Brunauer–Emmett–Teller and temperature-programmed desorption. The reaction was prepared with a catalyst loading of 1 % to 6 % and a molar ratio of 2:1 to 25:1 for methanol:PFAD, while the reaction time was conducted for 30–240 mins and the reaction temperature was kept at 70 °C for each experiment set. In addition, a catalyst loading of 5 wt% and molar ratio of 20:1 for methanol:PFAD with the reaction time of 180 mins and reaction temperature of 70 °C were used as optimal condition parameters. For the sulfonated chicken bone catalyst, the percentage yield and conversion of biodiesel were 80.8% and 98.2%, respectively. In contrast, the percentage yield and conversion rate reached to 81.5% and 97.7%, respectively, for the the sulfonated cow bone catalyst. The biodiesel properties obtained were in accordance with ASTM standards. The percentage of FAME content was determined utilizing gas chromatography. The bones have been shown to be appropriate sustainable precursors for the synthesis of a novel, highly effective heterogeneous acid catalyst for biodiesel development.

AbstractThermodynamic properties of ethanol-glycerol dry reforming have been studied with the method of Gibbs free energy minimization for hydrogen production from ethanol-glycerol mixture. Equilibrium compositions were determined as a function of CO2/ethanol-glycerol molar ratios (CEG)(1:1-12:1) where ethanol-glycerol is 1:1; reforming temperatures (573-1273 K) at different pressures (1-50 bar). Optimum conditions for hydrogen production are temperatures between 1073 and 1273 K and CEG of 1:1 at 1 bar pressure, whereas temperatures above 1073 K and CEG ratio 1:1 and 1 bar are suitable for the production of synthesis gas. Higher pressure and higher CEG ratio does not encourage hydrogen formation. Under identified optimum conditions, carbon formation can be thermodynamically inhibited