Analysis and Experiment on Dynamic Prediction in Magnesium Hydride Hydrolysis as Hydrogen Generator

2013 ◽  
Author(s):  
Chung-Hsing Chao ◽  
Tien-Chien Jen ◽  
Yen-Hsi Ho
Keyword(s):  
Citric Acid ◽  
Reaction Rate ◽  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Paper Analysis ◽  
Hydrolysis Reaction ◽  
Molar Ratio ◽  
Dynamic Prediction ◽  
Geometrical Effect ◽  
Acid Catalyzed

In this paper, analysis and experimental verification for dynamic modeling of an acid-catalyzed magnesium hydride hydrolysis was used to predict the hydrogen generation yield, rate, and gravimetric hydrogen storage capacity. The result shows that the ratio citric acid to magnesium hydride, the geometric forms of MgH2, and the water handling are crucial to this reaction, while the higher temperatures tend to have faster rates of reactions. Furthermore, the zero-order prediction gives a good result only at a relatively low citric acid to magnesium hydride ratio or low hydrolysis reaction rate. The reaction order is approximately one while the citric acid/magnesium hydride molar ratio remains high or the rate of reaction is high. Finally, considering the geometrical effect on the acid-catalyzed MgH2 hydrolysis, the validated Langmuir equation was used to successfully predict the dynamic hydrogen generation fairly well for most hydrolysis reaction rate.

Hydrogen Generation From Acetic Acid Catalyzed Magnesium Hydride Using an On-Demand Hydrogen Reactor

2016 ◽  
Author(s):  
Tien-Chien Jen ◽  
Joshua Adeniran ◽  
Esther Akinlabi ◽  
Chung-Hsing Chao ◽  
Yen-Hsi Ho ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Organic Acid ◽  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction ◽  
Hydrogen Yield ◽  
Acetic Acid Concentration ◽  
External Temperature ◽  
On Demand ◽  
Acid Catalyzed

This study reports an acetic acid catalyzed hydrolysis reaction for hydrogen generation from magnesium hydride (MgH2) using an on-demand hydrogen reactor. Acetic acid, a weak and benign organic acid, has been reported as a single catalyst in hydrolysis reaction for hydrogen generation using other substrates, but this is the first study where acetic acid has been employed as a catalyst in a magnesium hydride hydrolysis reaction for hydrogen generation. In this study, the effects of MgH2 weight, acetic acid concentration and external temperature on hydrogen generation from MgH2 were examined. The results of the hydrolysis reaction indicated that the weight of MgH2 was the major factor influencing hydrogen generation, followed by the concentration of acetic acid while the effect of external temperature was insignificant. Similarly, hydrogen yield was proportional to the weight of MgH2 with a reported maximum hydrogen yield at each weight been: 0.4g (∼ 0.07 L); 0.8 g (∼ 0.125 L) and 1.2 g (∼1.285 L). The successful use of acetic acid in the study reinforced the versatility of the on-demand hydrogen reactor and as a scalable technology for hydrogen generation.

Hydrolysis of MgH2 in MgCl2 solutions as an effective way for hydrogen generation

2021 ◽  
pp. 38-52
Author(s):  
V. Berezovets ◽  
◽  
A. Kytsya ◽  
Yu. Verbovytskyy ◽  
I. Zavaliy ◽  
...  
Keyword(s):  
Hydrogen Generation ◽  
Strong Acid ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction ◽  
Hydrolysis Rate ◽  
Reaction Yield ◽  
Buffer Solution ◽  
Passivation Film ◽  
Products Of Reaction ◽  
Hydrolysis Of

Magnesium hydride (MgH2) has a high hydrogen storage capacity (7.6 wt%) and the Mg element is abundant on the earth. Due to its strong reduction ability, even at room temperature it can provide the hydrogen yield reaching 15.2 wt% H (1703 mL/g) when interacting with water, which makes it very attractive for the application in supplying hydrogen for autonomous H energy systems. However, the hydrolysis reaction is rapidly inhibited by the Mg(OH)2 passivation layer formed on the surface of MgH2. In order to remove the passivation film and improve the efficiency of the MgH2 hydrolysis process, several methods including alloying, ball milling, changing the aqueous solution, have been successfully utilized. In this paper the process of hydrolysis of magnesium hydride in aqueous solutions of MgCl2 used as a promotor of the interaction has been studied in detail. It was found that the initial hydrolysis rate, pH of the reaction mixture, and overall reaction yield are all linearly dependent of the logarithm of MgCl2 concentration. It has been shown that pH of the reaction mixture in the presence of MgCl2 is well described by considering a system “weak base and its salt with strong acid” type buffer solution. Reference data for this hydrolysis reaction were also carefully analyzed. The mechanism and the kinetic model of the process of MgH2 hydrolysis in water solutions involved passivation of the MgH2 surface by the formed Mg(OH)2 precipitate followed by its repassivation have been proposed. The obtained after the hydrolysis reactions precipitates were studied using XRD and EDS. It was found also that the final products of reaction consist of Mg(OH)2 (brucsite type) and remaining MgH2. This fact shows that the formation of solid species such as MgCl2 xMgO yH2O at the studied conditions is unlikely and decreasing of pH the reaction mixture has a different nature.

Hydrogen generation by hydrolysis reaction of magnesium hydride

2004 ◽  
Vol 39 (6) ◽  
pp. 2227-2229 ◽  
Author(s):  
Y. Kojima ◽  
K.-I. Suzuki ◽  
Y. Kawai
Keyword(s):  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Hydrolysis Reaction

Reaction of Magnesium Hydride with Water to Produce Hydrogen

2013 ◽  
Vol 302 ◽  
pp. 151-157 ◽  
Author(s):  
Chung Hsing Chao ◽  
Tien Chien Jen
Keyword(s):  
Citric Acid ◽  
Magnesium Hydroxide ◽  
Direct Contact ◽  
Room Temperature ◽  
Hydrogen Generation ◽  
Magnesium Hydride ◽  
Hydrogen Gas ◽  
Hydrolytic Reaction ◽  
The Cost ◽  
Water Hydrogen

In this paper, magnesium hydride was used to react with water to produce the hydrogen gas. Magnesium hydride is the chemical compound MgH2, which contains 7.66% by weight of hydrogen. Although the concept of reacting chemical hydride with water to produce hydrogen is not new, there have been a number of recent published papers which might be employed to power fuel cell devices for portable applications. Under the room temperature, the hydrolytic reaction between magnesium hydride and water to form a thin-layer of magnesium hydroxide on the outer surface impedes water from coming into direct contact with the magnesium hydride. The key to continual removal of the coherent magnesium hydroxide layer by adding a citric acid has the following conclusions. First, using this approach can reach the 6.4wt% of hydrogen. Finally, the cost of producing hydrogen from magnesium hydride-water hydrogen generation approach would cost approximately $15 per kg hydrogen.

Cyclization and acid-catalyzed hydrolysis of O-benzoylbenzamidoximes

1986 ◽  
Vol 51 (12) ◽  
pp. 2786-2797
Author(s):  
František Grambal ◽  
Jan Lasovský
Keyword(s):  
Reaction Rate ◽  
Kinetic Isotope ◽  
Acid Base Equilibrium ◽  
Mineral Acids ◽  
Kinetics Of Formation ◽  
Acid Catalyzed ◽  
Ph Scale ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Derivatives Of

Kinetics of formation of 1,2,4-oxadiazoles from 24 substitution derivatives of O-benzoylbenzamidoxime have been studied in sulphuric acid and aqueous ethanol media. It has been found that this medium requires introduction of the Hammett H0 function instead of the pH scale beginning as low as from 0.1% solutions of mineral acids. Effects of the acid concentration, ionic strength, and temperature on the reaction rate and on the kinetic isotope effect have been followed. From these dependences and from polar effects of substituents it was concluded that along with the cyclization to 1,2,4-oxadiazoles there proceeds hydrolysis to benzamidoxime and benzoic acid. The reaction is thermodynamically controlled by the acid-base equilibrium of the O-benzylated benzamidoximes.

scholarly journals Promising Immobilization of Industrial-Class Phospholipase A1 to Attain High-Yield Phospholipids Hydrolysis and Repeated Use with Optimal Water Content in Water-in-Oil Microemulsion Phase

2021 ◽  
Vol 11 (4) ◽  
pp. 1456
Author(s):  
Yusuke Hayakawa ◽  
Ryoichi Nakayama ◽  
Norikazu Namiki ◽  
Masanao Imai
Keyword(s):  
Water Content ◽  
Reaction Rate ◽  
Enzyme Reaction ◽  
Initial Reaction Rate ◽  
Industrial Applications ◽  
Molar Ratio ◽  
High Yield ◽  
Initial Reaction ◽  
Phospholipase A1 ◽  
Repeated Use

In this study, we maximized the reactivity of phospholipids hydrolysis with immobilized industrial-class phospholipase A1 (PLA1) at the desired water content in the water-in-oil (W/O) microemulsion phase. The optimal hydrophobic-hydrophilic condition of the reaction media in a hydrophobic enzyme reaction is critical to realize the maximum yields of enzyme activity of phospholipase A1. It was attributed to enzymes disliking hydrophobic surroundings as a special molecular structure for reactivity. Immobilization of PLA1 was successfully achieved with the aid of a hydrophobic carrier (Accurel MP100) combination with the treatment using glutaraldehyde. The immobilized yield was over 90% based on simple adsorption. The hydrolysis reaction was kinetically investigated through the effect of glutaraldehyde treatment of carrier and water content in the W/O microemulsion phase. The initial reaction rate increased linearly with an increasing glutaraldehyde concentration and then leveled off over a 6% glutaraldehyde concentration. The initial reaction rate, which was predominantly driven by the water content in the organic phase, changed according to a typical bell-shaped curve with respect to the molar ratio of water to phospholipid. It behaved in a similar way with different glutaraldehyde concentrations. After 10 cycles of repeated use, the reactivity was well sustained at 40% of the initial reaction rate and the creation of the final product. Accumulated yield after 10 times repetition was sufficient for industrial applications. Immobilized PLA1 has demonstrated potential as a biocatalyst for the production of phospholipid biochemicals.

scholarly journals Pd/C Synthesized with Citric Acid: An Efficient Catalyst for Hydrogen Generation from Formic Acid/Sodium Formate

2012 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhi-Li Wang ◽  
Jun-Min Yan ◽  
Hong-Li Wang ◽  
Yun Ping ◽  
Qing Jiang
Keyword(s):  
Citric Acid ◽  
Formic Acid ◽  
Hydrogen Generation ◽  
Sodium Formate ◽  
Efficient Catalyst

Synergistic effect of co-reactant promotes one-step oxidation of cyclohexane into adipic acid catalyzed by manganese porphyrins

2015 ◽  
Vol 93 (7) ◽  
pp. 696-701 ◽  
Author(s):  
Hui Li ◽  
Yuanbin She ◽  
Haiyan Fu ◽  
Meijuan Cao ◽  
Jing Wang ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Co Oxidation ◽  
Adipic Acid ◽  
Molar Ratio ◽  
Reaction Conditions ◽  
Catalyst Structure ◽  
Manganese Porphyrins ◽  
Co Oxidation Reaction ◽  
One Step ◽  
Acid Catalyzed

The synergistic effect of cyclohexane and cyclohexanone promoted synthesis of adipic acid catalyzed by [MnIIIT(p-Cl)PP]Cl with cyclohexane and cyclohexanone as co-reactants. The results showed that the conversions of cyclohexane and cyclohexanone were significantly enhanced because of the cyclohexanone synergistic effect, and the higher selectivity to adipic acid was obtained with dioxygen as an oxidant. The studies indicated that the co-oxidation of cyclohexane and cyclohexanone was influenced by the initial molar ratio of cyclohexanone and cyclohexane, catalyst structure, catalyst concentrations, and reaction conditions. The preliminary mechanism of the co-oxidation reaction of cyclohexane and cyclohexanone using [MnIIIT(p-Cl)PP]Cl as the catalyst was proposed.

Modified Technique for Measuring Platelet Aggregation

1997 ◽  
Vol 3 (3) ◽  
pp. 196-202 ◽  
Author(s):  
Alexander Kaplan ◽  
Svetlana Kaplan ◽  
Karen F. Marcoe ◽  
Lester R. Sauvage ◽  
William P. Hammond
Keyword(s):  
Platelet Aggregation ◽  
Citric Acid ◽  
Platelet Rich Plasma ◽  
Antiplatelet Agents ◽  
Current Approach ◽  
Molar Ratio ◽  
Maximum Height ◽  
Modified Technique ◽  
Aggregation Pattern

The turbidimetric method of Bom is the current approach for assessing the aggregation behavior of platelets. It has been of modest practical value, due to difficulty in standardizing laboratory techniques for plasma preparation and inadequate quantification of the aggregation process. We report a new technique of sedimented platelet rich plasma (SPRP) preparation that reduces the irregularities caused by factors associated with procuring and preparing blood samples and permits a more flexible protocol for laboratory practice. We quantified results with a platelet aggregation score, which is calculated by multiplying the ratio of the height of the initial wave of aggregation to the maximum height of the aggregation pattern by the total area under the aggregation curve and by the ratio of the whole blood platelet count and the number of platelets in the sample. Comparative analysis of platelet aggregation scores (n = 95) obtained with both plasma preparation techniques using a paired t test demonstrated no statistical differences ( t = 1.368, p = 0.174). To demonstrate the application of this modified method to evaluation of antiplatelet agents, the effects of aspirin and aspirin combined with citric acid on platelet aggregation were studied in vitro. The antiaggregatory effect of aspirin combined with citric acid was dependent on the pH and on their molar ratio, and was greater than the effect of aspirin alone. The SPRP protocol with platelet aggregation scoring methodology could be a valid alternative for measurement of the platelets' propensity to aggregate and the effect of antithrombotic treatments. Key Words: Platelet aggregation— Aspirin—Citric acid.

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