Decomposition Of Hydrous Hydrazine Research Articles

Editorial Expression of Concern: Visible light assisted hydrogen generation from complete decomposition of hydrous hydrazine using rhodium modified TiO2 photocatalysts.

Editorial Expression of Concern: Visible light assisted hydrogen generation from complete decomposition of hydrous hydrazine using rhodium modified TiO2 photocatalysts.

Hydrous hydrazine decomposition over Rh/Al2O3 catalyst: Experimental and CFD studies

Addressing challenges associated with fossil fuels emissions and contributing to a sustainable energy future is the main objective of the science community. Hydrogen (H2) is emerging as a promising future fuel promoting clean energy production. In this work, the catalytic decomposition of hydrous hydrazine was evaluated using a commercial 0.5 wt% Rh/Al2O3 catalyst for H2 generation. The reaction conditions for the catalyst were optimised in a batch reactor, and computational fluid dynamics (CFD) simulations were performed, accurately validating the results. CFD studies were also conducted on velocity and temperature magnitude and, reactant concentration and catalytic particles distribution in the reactor area, highlighting the key role of the systems’ uniformity on maximum H2 generation. This work is the first, to our knowledge, which uses computational simulation on hydrous hydrazine decomposition, contributing to better understand the reaction kinetics, providing insights for practical hydrogen applications.

Ultrafine nickel-rhodium nanoparticles anchored on two-dimensional vanadium carbide for high performance hydrous hydrazine decomposition at mild conditions

The development of heterogeneous supported nanocatalysts with a high kinetics combined with low cost is off importance but remains still challenged for hydrazine hydrate served as a promising hydrogen storage material. Herein, by virtue of surficial functional groups, ultrafine NiRh NPs were monodispersed on the two-dimensional V2C surface via a conventional wet chemical co-reduction. The optimized NiRh/V2C system demonstrates an excellent catalytic performance toward selectively catalyzing dehydrogenation of hydrazine hydrate, affording 100% H2 selectivity with the turnover frequency (TOF) value of 987.5 h−1 at 323 K. Such an enhancement is mainly attributed to synergistic effect of nanosystem, which will optimize local surface energy and promote electron transfer in NiRh/V2C system, thereby improving the kinetic selectivity of catalytic hydrazine hydrate decomposition. This work has provided a facile strategy for developing nanocatalysts with high kinetics that could enable huge industrial applications in the future.

Hydrogen Production from Hydrous Hydrazine Decomposition Using Ir Catalysts: Effect of the Preparation Method and the Support

Herein, Ir/CeO2 catalysts were prepared using the deposition–precipitation method with NaOH or urea as the precipitating agent or using sol immobilization with tetrakis(hydroxymethyl)phosphonium chloride (THPC) as the protective and reducing agent. The effect of the preparation method on Ir catalyst activity was evaluated in the liquid-phase catalytic decomposition of hydrous hydrazine to hydrogen. Ir/CeO2 prepared using sol immobilization and DP NaOH showed the best activity (1740 h−1 and 1541 h−1, respectively) and yield of hydrogen (36.6 and 38.9%). Additionally, the effect of the support was considered, using TiO2 and NiO in addition to CeO2. For this purpose, the sol immobilization of preformed nanoparticles technique was considered because it allows the same morphology of the immobilized particles to be maintained, regardless of the support. Ir deposited on NiO resulted in the most selective catalyst with a H2 yield of 83.9%, showing good stability during recycling tests. The catalysts were characterized using different techniques: X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with an X-ray detector (EDX) and inductively coupled plasma–mass spectroscopy (ICP-MS).

Recent progress for hydrogen production from ammonia and hydrous hydrazine decomposition: A review on heterogeneous catalysts

In response to the growing trend of greenhouse gas emissions from the production and use of conventional fuels, COx free hydrogen generation is introduced as an alternative and efficient energy carrier. Due to hydrogen’s storage challenges, is more efficient to be produced on-site by other chemical compounds for fuel cell applications. This work outlines the production of hydrogen (H2) from ammonia (NH3) and hydrous hydrazine (N2H4·H2O) catalytic decomposition. Both substances are giving nitrogen (N2) as a by-product, which is not toxic. Moreover, heterogeneous catalysts that were studied through the years are presented. Lastly, a reactoristic view of the ammonia decomposition is provided with different reactors such as catalytic membrane reactors (CMRs), fixed-bed reactors (FBRs) and micro-reactors (MRs) for the evaluation of their performance.

Fine-tuning catalytic performance of ultrafine bimetallic nickel-platinum on metal-organic framework derived nanoporous carbon/metal oxide toward hydrous hydrazine decomposition

Heterogeneous catalysts with a high performance as well as low cost is pivotal but still challenging for hydrous hydrazine (N2H4·H2O) as a hydrogen storage material. Herein, bimetallic PtNi nanoparticles are well dispersed on nitrogen doped porous carbon/zirconia support (PtNi/NC-ZrO2). PtNi/NC-ZrO2 nanocatalysts could be responsive and completely for catalyzing hydrous hydrazine decomposition with a H2 selectivity of 100% as well as a turnover frequency of 1716 h−1 measured at 323 K, outperforming most heterogeneous metal catalysts. This is mainly attributed that bi-support NC-ZrO2 can efficiently expedite the electron transfer to metallic NPs and re-construct the electronic structure bimetallic active sites for selectively catalyzing hydrous hydrazine decomposition.

Enhanced stability of sub-nanometric iridium decorated graphitic carbon nitride for H2 production upon hydrous hydrazine decomposition.

Stabilizing metal nanoparticles is vital for large scale implementations of supported metal catalysts, particularly for a sustainable transition to clean energy, e.g., H2 production. In this work, iridium sub-nanometric particles were deposited on commercial graphite and on graphitic carbon nitride by a wet impregnation method to investigate the metal-support interaction during the hydrous hydrazine decomposition reaction. To establish a structure-activity relationship, samples were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The catalytic performance of the synthesized materials was evaluated under mild reaction conditions, i.e. 323 K and ambient pressure. The results showed that graphitic carbon nitride (GCN) enhances the stability of Ir nanoparticles compared to graphite, while maintaining remarkable activity and selectivity. Simulation techniques including Genetic Algorithm geometry screening and electronic structure analyses were employed to provide a valuable atomic level understanding of the metal-support interactions. N anchoring sites of GCN were found to minimise the thermodynamic driving force of coalescence, thus improving the catalyst stability, as well as to lead charge redistributions in the cluster improving the resistance to poisoning by decomposition intermediates.

Effects of oxygen functionalities on hydrous hydrazine decomposition over carbonaceous materials.

Metal-free heterogeneous catalysis is promising in the context of H2 generation. Therefore, establishing structure-activity relationships is a crucial issue to improve the development of more efficient catalysts. Herein, to evaluate the reactivity of the oxygen functionalities in carbonaceous materials, commercial functionalized pyrolytically stripped carbon nanofibers (CNFs) were used as catalysts in the liquid-phase hydrous hydrazine decomposition process and its activity was compared to that of a pristine CNF material. Different oxygenated groups were inserted by treating CNFs with hydrogen peroxide for 1 h (O1-H2O2) and HNO3 for 1 h (O1-HNO3) and 6 h (O6-HNO3). An increase in activity was observed as a function of the oxidizing agent strength (HNO3 > H2O2) and the functionalization time (6 h > 1 h). A thorough characterization of the catalysts demonstrated that the activity could be directly correlated with the oxygen content (O6-HNO3 > O1-HNO3 > O1-H2O2 > CNFs) and pointed out the active sites for the reaction at carbon-oxygen double bond groups (CO and COOH). Systematic DFT calculations supported rationalization of the experimental kinetic trends with respect to each oxygen group (CO, C-O-C, C-OH and COOH).

Mn‐Modified Graphitic Carbon Nitride‐Supported Bimetallic PtNi Nanoparticles for Hydrogen Generation from Hydrous Hydrazine

AbstractMn‐modification, as a method of material element modification, has a vital efficacy on the structure of materials, providing abundant active sites for the loading of metal nanoparticles. Herein, highly dispersed PtNi nanoparticles deposited on Mn‐modified graphitic carbon nitride (g‐C3N4) was synergistically constructed by a facile and valid impregnation reduction method. Interestingly, among all the tested samples, the obtained Pt0.6Ni0.4/(MnOx)2‐C3N4 display perfect catalytic activity towards decomposition of hydrous hydrazine to produce hydrogen in alkaline solution, with the value of turnover frequency (TOF) is 2749 h−1 at 323 K. Simultaneously, the as‐synthetic catalyst remains outstanding hydrogen selectivity and stability after five recycles. This work proposes a novel strategy for structural modification catalysts to enhance the catalytic performance for dehydrogenation of hydrous hydrazine.

Analysis and recompilation of kinetic data about the hydrogen production by the catalytic decomposition of hydrous hydrazine

The kinetics of the catalytic decomposition of hydrous hydrazine was determined for the experimental data published in 23 articles. The acquired database contains 139 data sets having 2038 data points. The collected data were analyzed by the integral method, which revealed that hydrazine decomposition follows power-law kinetics. The calculated values of apparent activation energies ranges between 22 and 64 kJ/mol - average value 50.3 kJ/mol, while the reaction orders concerning hydrazine concentration range between 0 and 0.64 - average value 0.33. Analysis showed that the catalyst support significantly impacts the reaction mechanism and activation energy. On average, the catalyst durability was tested by 7.1 cycles, and catalysts retained 69% of their initial activity. The average value of turnover number (TON) is 142, while the estimated value of TON for automotive applications ranges from 105–106, far above the value evaluated on the basis of the reported durability tests.

Comments on: Noble-metal-free NiCu/CeO2 catalysts for H2 generation from hydrous hydrazine

The results of two previously published articles about the catalytic decomposition of hydrous hydrazine were analyzed. Experimentally it was shown that Ni0.5Cu0.5/CeO2 catalyst is more active than Ni/CeO2. However, the measured impact of external mass transport on the observed decomposition rate contradicts heterogeneous catalysis's fundamental chemical engineering principles. The observed deviation could be described only by the copper-induced homogeneous reaction.

Hydrous Hydrazine Decomposition for Hydrogen Production Using of Ir/CeO2: Effect of Reaction Parameters on the Activity.

In the present work, an Ir/CeO2 catalyst was prepared by the deposition–precipitation method and tested in the decomposition of hydrazine hydrate to hydrogen, which is very important in the development of hydrogen storage materials for fuel cells. The catalyst was characterised using different techniques, i.e., X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM) equipped with X-ray detector (EDX) and inductively coupled plasma—mass spectroscopy (ICP-MS). The effect of reaction conditions on the activity and selectivity of the material was evaluated in this study, modifying parameters such as temperature, the mass of the catalyst, stirring speed and concentration of base in order to find the optimal conditions of reaction, which allow performing the test in a kinetically limited regime.

Recent Progress on Catalysts for Hydrogen Evolution from Decomposition of Hydrous Hydrazine

Recent Progress on Catalysts for Hydrogen Evolution from Decomposition of Hydrous Hydrazine

Nitrogen-functionalized carbon nanotube-supported bimetallic PtNi nanoparticles for hydrogen generation from hydrous hydrazine.

Herein, ultrafine PtNi nanoparticles (NPs) supported on N-functionalized multi-walled carbon nanotubes (N-MWCNTs) were facilely obtained. The N species on N-MWCNTs not only benefit the formation of PtNi NPs but also accelerate the dehydrogenation of hydrous hydrazine, affording a high turnover frequency of 1595 h-1 with 100% H2 selectivity. In addition, the N species can be used as an "anchor" to stabilize the bimetallic NPs and efficiently restrain the aggregation, giving robust stability of the catalysts for decomposition of hydrous hydrazine over PtNi/N-MWCNTs.

Silica supported ternary NiRuPt alloy nanoparticles: Highly efficient heterogeneous catalyst for H2 generation via selective decomposition of hydrous hydrazine in alkaline solution

Hydrous hydrazine (H2NNH2.H2O, HH) is taken notice to be one of the promising hydrogen storage materials for the future due to its high hydrogen content of 7.9% wt. In this study, we develop a new catalytic material formed from trimetallic NiRuPt alloy nanoparticles decorated on silica support (NiRuPt/SiO2) for the hydrogen production via selective decomposition of HH under mild reaction conditions. NiRuPt/SiO2 catalyst was prepared by wet-impregnation technique in water at room conditions and characterized by the various spectroscopic/analytical tools. The sum of their results is revealing that the formation ternary NiRuPt alloy (dmean = 6.4 nm) nanoparticles on the surface of SiO2. The prepared new catalytic system eases the selective hydrogen production from decomposition of HH in aqueous alkaline solution with high activity (324.1 min−1) and conversion (>99%) at 333 K. Furthermore, painless recovery plus high durability of these supported NiRuPt nanoparticles against to agglomeration and leaching make them recyclable catalyst so that they retain >70% of their activity at 5th reuse and the ex-situ generated NiRuPt/SiO2 catalyst was found to provide total turnover number (TTON) 4181 in the complete decomposition of HH over 11.4 h before deactivation in the complete decomposition of HH. The studies addressed herein also includes the collection of kinetic records for NiRuPt/SiO2 catalyzed decomposition of HH in alkaline solution depending on catalyst [NiRuPt], substrate [H2NNH2.H2O], promoter [NaOH] concentrations and temperature to determine the rate expression and the activation parameters (Ea, ΔH#, and ΔS#) of the catalytic reaction.

Effect of Silica Content on Support-Iridium Active Phase Interactions on the Nanocatalyst Activity

To discuss the potential role of the support for iridium catalyst, we have proceeded to prepare a series of supported catalysts with the same active phase content, but different silica content, to elucidate the changes in surface structure and the reaction process of hydrous hydrazine decomposition on catalyst. The obtained iridium catalysts contained 20 wt% of nanoparticles dispersed on spherical mesoporous alumina and aluminosilicate supports for hydrogen generation from hydrous hydrazine. Iridium nanoparticles with different morphologies and diameters could be produced over the catalyst supports depending on its nature. The iridium catalysts were characterized by some techniques such as XRD, FESEM, BET, TGA, H2-TPR, and mechanical properties. The type of catalyst support played an important role in the effectiveness of the catalyst particles, leading to different activities for hydrazine monohydrate decomposition. Under the given test conditions, the performance of the catalyst was better when using alumina granular as the catalyst support than when using aluminosilicate granular. Since the aluminosilicate support was less reactive than the alumina, hydrogen selectivity was relatively small; consequently, the reaction rate was lower when using the aluminosilicate support than when using the alumina support.

Retraction: Mesoporous multiwalled carbon nanotubes as supports for monodispersed iron–boron catalysts: improved hydrogen generation from hydrous hydrazine decomposition

Retraction of ‘Mesoporous multiwalled carbon nanotubes as supports for monodispersed iron–boron catalysts: improved hydrogen generation from hydrous hydrazine decomposition’ by Dong Ge Tong et al., J. Mater. Chem. A, 2013, 1, 358–366.

Development of novel supported iridium nanocatalysts for special catalytic beds

In the present paper, an experimental study of the catalytic decomposition of hydrous hydrazine was investigated on the different structural forms of the catalyst. The synthesized iridium catalysts have been usually used directly and have not been evaluated in the laboratory reactor. This study includes the preparation of iridium-based catalysts supported on spherical (alumina), honeycomb monoliths (cordierite) and foams (alumina) for the evaluation of catalytic activity in the laboratory reactor. The characterizations of these catalysts were evaluated by the TGA, FESEM and BET analysis. The result of the catalytic characterization of monolithic support was shown a homogeneous distribution of active metal without any problem of sintering (average size 25 nm) on the support surface. While the surface of the spherical and foam supports were shown non-uniform distribution of nanoparticles on the support skeleton (average size 55 nm). The monolithic catalyst exhibits higher decomposition rate and H2 selectivity than other supports due to uniform in shape and particle size distribution.Graphic abstract

Noble Metal‐free Bimetallic Cobalt/Manganese Oxide Catalyst for Hydrogen Generation by Decomposition of Hydrous Hydrazine

Bimetallic cobalt and manganese oxide (Co/MnO) is prepared by annealing the spinel structure of CoMn2O4 under hydrogen environment. This noble metal‐free catalyst is applied for hydrogen generation from aqueous hydrazine solution. X‐ray powder diffraction, transmission electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy results indicated that the phase separation of metallic cobalt and manganese monoxide from CoMn2O4 occurs during annealing process. Co/MnO exhibits catalytic activity with the TOF value of 14.2 h−1 and 100% selectivity without generation of ammonia at 343 K. It is found that metallic cobalt plays role on the active site for hydrogen generation.

Au Based Ni and Co Bimetallic Core Shell Nanocatalysts for Room Temperature Selective Decomposition of Hydrous Hydrazine to Hydrogen

AbstractNickel and Cobalt bimetallic catalysts with Au as core metal has been synthesized and demonstrated for hydrazine decomposition reaction for producing hydrogen. Gold‐cobalt and gold nickel bimetallic system belonging to the class of strained structures with high lattice mismatch of approximately 14% are demonstrated for synergistic effects atypical of monometallic counterparts for the selective decomposition of hydrous hydrazine to H2 with N2 as the other product at room temperature.