Hydrogen Generation in Water Splitting Reaction Using Aluminum: Effect of NaOH Concentration and Reaction Modelling Using SCM

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Shyam P. Tekade ◽  
Diwakar Z. Shende ◽  
Kailas L. Wasewar
Keyword(s):  
Hydrogen Generation ◽  
Heterogeneous Reaction ◽  
Reaction Rate Constant ◽  
Average Value ◽  
First Order Kinetics ◽  
Controlling Mechanism ◽  
Metal Aluminum ◽  
Shrinking Core ◽  
Aluminum Effect ◽  
Average Size

Abstract The kinetics of the heterogeneous reaction of metal aluminum with water was studied in presence of NaOH as an activator for generating the hydrogen. Aluminum (Al) powder of average size of 100 µm and foil of thickness of 11 µm were utilized to study the effect of the shape of particles of aluminum on hydrogen generation. The hydrogen generation was reported at various concentrations of NaOH, ranging from 0.12 N to 0.67 N. The fractional conversion of Al was found to be 0.66 at 0.12 N and 1.0 at 0.185 N, 0.37 N, 0.54 N, 0.65 N NaOH concentration. The activation energy of the reaction has been determined at the stoichiometric concentration of 0.185 N NaOH at the temperature ranging from 298 to 323 K. An attempt was made to model the reaction using Shrinking Core Model (SCM) for determining the rate controlling mechanism for the heterogeneous reaction. The reaction was observed to follow the first order kinetics and the average value of reaction rate constant using Al power and foil was found to be 27.322 x 10-4 cm/min and 2.125 x 10-4 cm/min respectively.

Potassium Hydroxide Activated Hydrogen Generation Using Aluminum in Water Splitting Reaction

2018 ◽  
Vol 17 (3) ◽  
Author(s):  
Shyam P. Tekade ◽  
Diwakar Z. Shende ◽  
Kailas L. Wasewar
Keyword(s):  
Water Splitting ◽  
Potassium Hydroxide ◽  
Hydrogen Generation ◽  
Foil Thickness ◽  
Aluminum Particles ◽  
Controlling Mechanism ◽  
Different Temperatures ◽  
Shrinking Core ◽  
Alkaline Activator ◽  
Experimental Runs

Abstract The water splitting reaction using aluminum represents one of the best methods for on-demand hydrogen requirements. The present paper describes the hydrogen generation in water splitting reaction using aluminum in presence of potassium hydroxide as an alkaline activator. The effect of concentration of KOH, temperature, and shape of aluminum particles on the hydrogen generation in water splitting reaction was experimentally studied using various concentrations of aqueous KOH viz. 0.25 N, 0.50 N, 0.75 N and 1.0 N, at different temperatures of 30 °C, 40 °C, and 50 °C for Al powder (diameter: 200 mesh) and Al foil (thickness: 11 microns). The complete conversion of Al was recorded for all the experimental runs. The average hydrogen generation rate was found to vary between 3.40 ml/min to 21 ml/min per 0.1 g aluminum under considered concentrations and temperatures. The shrinking core model was applied to the experimental data for predicting the rate controlling mechanism.

Hydrogen Generation in an Annular Micro-Reactor: An Experimental Investigation and Reaction Modelling by Shrinking Core Model (SCM)

2018 ◽  
Vol 16 (7) ◽  
Author(s):  
Shyam P. Tekade ◽  
Diwakar Z. Shende ◽  
Kailas L. Wasewar
Keyword(s):  
Experimental Investigation ◽  
Water Splitting ◽  
Hydrogen Generation ◽  
Energy Requirement ◽  
Reaction System ◽  
Core Model ◽  
Shrinking Core Model ◽  
Flow Rates ◽  
Metal Aluminum ◽  
Shrinking Core

Abstract Hydrogen can be one of the key elements as source of future energy requirement. Water splitting reaction is an important route for generation of hydrogen as maximum fraction of hydrogen constitute in water. The present work describes the experimental investigation for generation of hydrogen through water splitting reaction in flow conditions with the aid of metal aluminum and sodium hydroxide as an activator. The hydrogen generation through water splitting reaction at various concentrations of NaOH, viz. 0.5 N and 1 N and the flow rates ranging from 0.2 to 10 ml/min was studied. The yield of hydrogen generated is reported for each NaOH concentration and flow rate. The yield of hydrogen generated at all the considered concentrations and flow rates was found to be greater than 98 %. The shrinking core model has been modified and developed for predicting the conversion of aluminum in the reaction system as per the prevailing conditions and rate controlling mechanism. The RMSE value of predicted conversion of Al was found to be 0.0351 which signify that the model agrees well with the experimental data.

scholarly journals The Efficient Photocatalytic Degradation of Organic Pollutants on the MnFe2O4/BGA Composite under Visible Light

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1276
Author(s):  
Qian Li ◽  
Xiaoyu Jiang ◽  
Yongfu Lian
Keyword(s):  
Rhodamine B ◽  
Synergetic Effect ◽  
Reaction Rate Constant ◽  
Experimental Conditions ◽  
First Order Kinetics ◽  
Boron Doped ◽  
Fenton Catalyst ◽  
Aerogel Composite ◽  
Doped Graphene ◽  
Apparent Reaction Rate Constant

The MnFe2O4/BGA (boron-doped graphene aerogel) composite was prepared by hydrothermal treatment of MnFe2O4 particles, boric acid, and graphene oxide. When applied as a photo-Fenton catalyst for the degradation of rhodamine B, the MnFe2O4/BGA composite yielded a degradation efficiency much higher than the sum of those of individual MnFe2O4 and BGA under identical experimental conditions, indicating a strong synergetic effect established between MnFe2O4 and BGA. The catalytic degradation of rhodamine B was proved to follow pseudo first-order kinetics, and the apparent reaction rate constant on the MnFe2O4/BGA composite was calculated to be three- and seven-fold that on BGA and MnFe2O4, respectively. Moreover, the MnFe2O4/BGA composite also demonstrated good reusability and could be reused for four cycles without obvious loss of photocatalytic activity.

Hydrogen Generation in an Annular Micro-Reactor: an Experimental Investigation of Water Splitting Reaction Using Aluminum in Presence of Potassium Hydroxide

2018 ◽  
Vol 17 (2) ◽  
Author(s):  
Shyam P. Tekade ◽  
Diwakar Z. Shende ◽  
Kailas L. Wasewar
Keyword(s):  
Water Splitting ◽  
Potassium Hydroxide ◽  
Hydrogen Generation ◽  
Energy Content ◽  
Average Rate ◽  
High Energy ◽  
Low Flow ◽  
Flow Rates ◽  
Metal Aluminum ◽  
Micro Reactor

Abstract Hydrogen is one of the important non-conventional energy sources because of its high energy content and non-polluting nature of combustions. The water splitting reaction is one of the significant methods for hydrogen generation from non-fossil feeds. In the present paper, the hydrogen generation has been experimentally investigated with water splitting reaction using metal aluminum in presence of potassium hydroxide as an activator under flow conditions. The rate of hydrogen generation was reported in the annular micro- reactor of 1 mm annulus using various flow rates of aqueous 0.5 N KOH ranging from 1 ml/min to 10 ml/min. The complete conversion of aluminum was observed at all the flow rates of aqueous KOH. The hydrogen generation rate was observed to depend on the flow rate of liquid reactant flowing through the reactor. At 1 ml/min of 0.5 N KOH, hydrogen generates at an average rate of 3.36 ml/min which increases to 10.70 ml/min at 10 ml/min of aqueous KOH. The Shrinking Core Model was modified for predicting the controlling mechanism. The rate of hydrogen generation was observed to follow different controlling mechanisms on various time intervals at low flow rates of aqueous KOH. It was observed that chemical reaction controls the overall rate of hydrogen generation at higher flow rates of aqueous KOH.

scholarly journals Research on hydrogen generation from rapid hydrolysis of aluminum in sodium fluoride solution

2019 ◽  
Vol 118 ◽  
pp. 03048
Author(s):  
Changchun Li ◽  
Yuxin Wu
Keyword(s):  
Hydrogen Production ◽  
Kinetic Model ◽  
Sodium Fluoride ◽  
Hydrogen Generation ◽  
Hydrogen Yield ◽  
Shrinking Core Model ◽  
Fluoride Solution ◽  
Shrinking Core ◽  
Rapid Hydrolysis ◽  
Hydrolysis Of

Hydrogen generation from rapid hydrolysis of aluminum in sodium fluoride solution was investigated through a hydrolysis experiment. Rapid and instant hydrogen yield were observed using sodium fluoride as additive. The experimental results demonstrate that the increase of temperature and the amount of additives in a certain range will boost the hydrogen production. The amount of additives outside the range only has an effect on the rapid hydrolysis of the aluminum during the initial stage, but the total amount of hydrogen produced doesn’t increased significantly. Theoretical analysis of the effects of the mixing ratio and the temperature on the hydrogen production rates were performed using the shrinking core model and the kinetic model. The shrinking core model parameter a and k indicate the film change degree of porosity and thickness and the effect of time on the diffusion coefficient. the kinetic model is verified and the activation energy confirming hydrogen yield control by a molecular diffusion process. Correspondingly, mechanisms of Al corrosion in NaF solutions under low and high alkalinity were proposed, respectively.

Effect of homogeneous and heterogeneous reactions on the dispersion of a solute in the laminar flow between two plates

1972 ◽  
Vol 330 (1580) ◽  
pp. 59-63 ◽  
Keyword(s):  
Diffusion Coefficient ◽  
Rate Constant ◽  
Reaction Rate ◽  
Heterogeneous Reaction ◽  
Reaction Rate Constant ◽  
Heterogeneous Reactions ◽  
Parallel Plates ◽  
Homogeneous And Heterogeneous Reactions ◽  
First Order Chemical Reaction ◽  
Taylor Diffusion

The paper presents an analytical solution for the dispersion of a solute in a liquid flowing between two parallel plates in the presence of an irreversible first-order chemical reaction. The effects of both homogeneous and heterogeneous reactions on the dispersion are studied under isothermal conditions. It is found that for homogeneous reaction in the bulk of the liquid, the effective Taylor diffusion coefficient decreases with increase in the reaction rate constant. Further for heterogeneous reaction at the catalytic walls, Taylor diffusion coefficient is also found to decrease with increase in the wall catalytic parameter for fixed reaction rate constant corresponding to the bulk reaction.

scholarly journals The Influence of Spherical Nano-SiO2 Content on the Thermal Protection Performance of Thermal Insulation Ablation Resistant Coated Fabrics

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Guoyi Liu ◽  
Yuanjun Liu ◽  
Xiaoming Zhao
Keyword(s):  
Thermal Insulation ◽  
Thermal Protection ◽  
Radiant Heat ◽  
Total Heat Flow ◽  
Residual Mass ◽  
Average Value ◽  
Coated Fabrics ◽  
Average Size ◽  
In Fire ◽  
Protective Performance

In the high temperatures experienced in fire, radiant heat accounts for 80% of the total heat flow; therefore, improving the radiation protection is the best way to enhance the thermal protective performance of thermal insulation ablation resistant coated fabrics. To achieve this goal, the coating process and the ingredients used were optimized, spherical nano-SiO2 and other particles were added, and thermal insulation ablation resistant coated fabrics with high radiant heat reflectivity were prepared. The influence of the spherical nano-SiO2 content on the thermal protection performance of the prepared coated fabrics was investigated. Research showed that (1) the radiant heat reflectivity of the prepared coated fabrics improves significantly with increasing content of spherical nano-SiO2; when the mass fraction of spherical nano-SiO2 is 15%, the reflectivity of coated fabrics is at its largest, and its average value was 74.30%. At present, the average size of grains in samples increased 1.9 times; (2) after adding the spherical nano-SiO2, the thermal stability of the thermal insulation ablation resistant coated fabrics is significantly improved; the residual mass is as high as 88.49% at 1200°C, which is 18.77% higher than the residual mass of the coated fabrics with no spherical nano-SiO2 added at the same temperature.

Experimental Study on the Hydrogen Storage Properties of LaNi5 Alloy in Repeated Hydriding/Dehydriding Cycles

2013 ◽  
Vol 815 ◽  
pp. 25-30 ◽  
Author(s):  
Xin Xin Cao ◽  
Fu Sheng Yang ◽  
Zhen Wu ◽  
Yu Qi Wang ◽  
Zao Xiao Zhang
Keyword(s):  
Hydrogen Storage ◽  
Reaction Rate ◽  
Plateau Pressure ◽  
Reaction Rate Constant ◽  
Oxidation Products ◽  
Equilibrium Pressure ◽  
Hydrogen Storage Properties ◽  
Jma Model ◽  
Controlling Mechanism ◽  
Storage Properties

LaNi5 alloy is one of the promising materials for hydrogen storage. It has good activation property, fast reaction rate and moderate plateau pressure. However, some of its hydrogen storage properties will change after repeated hydriding/dehydriding cycles, which limits its practical application. Therefore, this paper investigated the cycling properties of LaNi5 alloy by volumetric method. The results showed that the reaction rate increased with cycling. The hydriding/dehydriding hydrogen content decreased with cycling. For hydriding reaction, the equilibrium pressure increased with cycling, while it decreased for dehydriding at 40°C and 60°C. After 100 cycles, the LaNi5 alloy has been severely pulverized and oxygenated. The oxidation products include LaNiO2, La2NiO4, La2NiO4.18 and LaNiO3. The JMA model was found to fit the kinetic data well, suggesting a nucleation and growth controlling mechanism. The intrinsic reaction rate constant ka increases from 21.87 s-1to 24.81 s-1, while the activation energy decreases from the initial value of 19459 to 19373 J/mol after 100 cycles.

scholarly journals Sulfonated Hydrothermal Carbon-Based Catalyzed Esterification under Microwave Irradiation: Optimization and Kinetic Study

2020 ◽  
Vol 15 (2) ◽  
pp. 514-524
Author(s):  
Laddawan Tumkot ◽  
Armando T. Quitain ◽  
Tetsuya Kida ◽  
Navadol Laosiripojana ◽  
Artiwan Shotipruk ◽  
...  
Keyword(s):  
Microwave Irradiation ◽  
Reaction Rate Constant ◽  
Molar Ratio ◽  
Catalyst Loading ◽  
Esterification Reaction ◽  
Good Prediction ◽  
Molar Ratios ◽  
First Order Kinetics ◽  
A Value ◽  
Carbon Based

In this study, the esterification reaction of oleic acid (OA) with methanol was investigated in the presence of a sulfonated hydrothermal carbon-based catalyst under microwave irradiation. The reaction conditions were optimized using response surface methodology based on a central composite design. Three following variables were studied: methanol to OA molar ratios (2.5:1–7.5:1), reaction time (50–70 min) and catalyst loading (2–5 wt.%) to provide a statistical model with the coefficient of regression (R2) of 0.9407. Based on the model, the optimum OA conversion of 95.6% was predicted at 5.8:1 methanol to OA molar ratio, 60 min and 3.05 wt.% catalyst loading. The experimental validation indicated that the model gave a good prediction of OA conversion (2.8% error). Furthermore, the reaction was found to be reasonably described by the pseudo-first order kinetics. The dependency of the reaction rate constant on temperatures gave a value of the activation energy of 64 kJ/mol. Copyright © 2020 BCREC Group. All rights reserved 

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