Low-temperature Hydrogen Production Research Articles

Low-temperature hydrogen production from waste polyethylene by nonthermal plasma (NTP)-assisted catalytic pyrolysis using NiCeOx/β catalyst

Conventional catalytic pyrolysis of waste plastics for H2 production faces challenges due to excessively high reaction temperatures. This study introduced a NiCeOx/β catalyst for low-temperature H2 production from polyethylene (PE), aiming to enhance H2 yield through nonthermal plasma (NTP) and catalytic active sites. Experimental results confirmed the efficacy of NTP in promoting collision between high-potential-energies active species and plasma-catalyst interactions, identifying acidic sites as primary catalytic active sites. Both experiments and density functional theory (DFT) calculations confirmed NiO and CeO2 particles as metallic active sites, exhibiting thermodynamic and kinetic benefits for primary products from PE pyrolysis. Under optimal conditions, the highest H2 yield and selectivity respectively reached 32.71 mmol/g and 82.10 % at a PE/(NiCeOx/β) ratio of 1:4, reaction temperature of 400 °C, and NTP discharge power of 210 W. The NiCeOx/β catalyst facilitated low-temperature pyrolysis of waste plastics, enhancing H2 selectivity and yield.

Low temperature hydrogen production from H2S with metal tin by cyclic two-step method

Hydrogen sulfide (H2S) is not only a highly toxic and corrosive gas commonly present in the natural gas reservoir, but also valuable resource rich in hydrogen and sulfur. The Claus process is commonly used in industry to handle H2S, but it has the disadvantages of generation of SO2 and waste of hydrogen resources. Alternatively, cyclic two-step decomposition of H2S can generate H2 at low temperatures, which has been testified recently. Herein we report a method of splitting H2S into H2 and S with Sn metal in two steps at a low temperature for the first time. The experimental results demonstrate that the maximum yield of H2 can reach 33% at temperatures as low as 300 °C, and the metal Sn could be regenerated at elevated temperature. This research presents a novel approach for the decomposition of H2S to produce H2 and sulfur under relatively mild conditions, thereby opening up further opportunities for future studies on the value-added utilization of H2S.

Low-temperature hydrogen production and consumption in partially-hydrated peridotites in Oman: implications for stimulated geological hydrogen production

The Samail Ophiolite in Oman, the largest exposed body of ultramafic rocks at the Earth’s surface, produces a continuous flux of hydrogen through low-temperature water/rock reactions. In turn, the scale of the subsurface microbial biosphere is sufficient to consume much of this hydrogen, except where H2 is delivered to surface seeps via faults. By integrating data from recent investigations into the alteration history of the peridotites, groundwater dynamics, and the serpentinite-hosted microbial communities, we identify feasible subsurface conditions for a pilot demonstration of stimulated geological hydrogen production. A simple technoeconomic analysis shows that the stimulation methods to be used must increase the rate of net hydrogen production at least 10,000-fold compared to the estimated natural rate to economically produce hydrogen from engineered water/rock reactions in the peridotite formations. It may be possible to meet this challenge within the upper 1–2 km, given the projected availability of reactive Fe(II)-bearing phases and the lower drilling costs associated with shallower operations. Achieving ≥10,000-fold increases in the H2 production rate will require a combination of stimuli. It will likely be necessary to increase the density of fracturing in the reaction volume by at least two orders of magnitude. Then, the H2-production rates must also be increased by another two orders of magnitude by increasing the water/rock ratio and modifying the chemistry of the injected fluids to optimize formation of Fe(III)-bearing secondary phases. These fluid modifications must be designed to simultaneously minimize microbial consumption of H2 within the stimulation volume. In contrast, preserving the high potentials for biological H2 consumption in the shallow groundwaters replete with oxidants such as nitrate, sulfate and dissolved inorganic carbon will reduce the potential for any inadvertent leaks of hydrogen to the atmosphere, where it acts as an indirect greenhouse gas.

Performance of Anion Exchange Membrane Water Electrolysis with High Ionic Strength Electrolyte

Anion exchange membrane water electrolysis (AEMWE) provides the advantages of conventional alkaline water electrolysis and proton exchange membrane water electrolysis for low-temperature hydrogen production. This study investigates the effect of ionic strength in low hydroxide concentration anolyte on AEMWE performance. The anolyte was recirculated at the anode, and the cathode was operated dry. Different alkali cations in the high ionic strength anolyte improved the cathode overpotential by increasing the water transport from the anode to the cathode. Li+, Na+, K+, and Cs+ cations were tested with K+ providing the lowest electrolysis overpotential among the cations tested. The transference number of the alkali cations was measured by a modified Bruce-Vincent method using a membrane electrode assembly, composed of a hydrogen-evolving cathode and oxygen-evolving anode and anion exchange polymer membrane. The result shows that the cathode overpotential is influenced by the cation mobility, which is related to the hydration shell width. The electrolysis overpotential trend with different alkali cations in the anolyte scaled with the alkali dynamic ionic radius. Durable electrolysis was performed in 1,000 h test at 60 °C and 1 A cm−2.

A proposal for advanced supplementary technologies and a hybrid system with gas-cooled fast reactor concept ALLEGRO

A coupling of advanced reactors with high-capacity energy storage and other innovative non–nuclear energy technologies is a way to increase the flexibility and utilisation factor of the future nuclear systems and to diversify its energy outputs. In this paper, the basic layout of a hybrid system for a gas-cooled fast reactor is proposed. The system is composed of a high-temperature thermal energy storage unit coupled with a supercritical CO2 conversion cycle and both low-temperature and high-temperature hydrogen production and utilization. As a reference GFR reactor, the ALLEGRO concept is considered. The paper describes state-of-the-art and overviews potentially applicable technologies. Selection and justification of concepts of the individual parts of the hybrid system including operational conditions is also given. The R&D needs necessary for the potential implementation of the system are identified and the activities ongoing in the Czech Republic and especially in Centrum Výzkumu Řež are also described.

Investigation on environmental stability and hydrolytic hydrogen production behavior of Mg30La alloy modified by activated carbon/expandable graphite

In the process of hydrogen production, Mg-based alloy is easily poisoned by the environment to form an inert oxide layer. The effect of carbon catalysts (AC、EG) on the environmental stability of short time high energy ball milling Mg30La alloy is explored by simulating the real environmental toxic conditions. The toxicity of Mg30La alloy with oxygen and oxygen without water and the anti-toxicity ability after surface modification are reported. The results show that Mg30La alloy has the highest initial hydrogen production rate before exposure, and the average rate is 88.66 mL g−1·min−1 in the first 5 min. But Mg30La-EG has a higher yield, reaching 91% at 60 min, 18% higher than that of Mg30La alloy without catalysis. The yield of Mg30La-AC is only 55% at 60 min. After the sample is exposed, the hydrolyzed hydrogen production test show that Mg30La-EG has a higher initial hydrogen production rate than Mg30La, reaching 87.5 mL g−1·min−1 in the first 2 min. However, Mg30La alloy has the highest hydrogen production capacity, 21% higher than Mg30La-AC and 20% higher than Mg30La-EG. In summary, after adding AC, the adsorption of activated carbon will lead to the formation of an inert layer on the surface, thus affecting the hydrolytic hydrogen production performance. However, after adding EG, hydrogen can be rapidly produced at room temperature, and the yield of Mg30La alloy can be significantly improved. However, long-term contact with the environment should be avoided before hydrogen production to ensure low temperature, rapid and efficient hydrogen production.

Improved Low-temperature Hydrogen Production from Aqueous Methanol Based on Synergism Between Cationic Pt and Interfacial Basic LaO x.

Aqueous phase reforming of methanol (APRM) is simple, inexpensive and provides a high hydrogen gravimetric density of 18.8 wt%, and so is superior to traditional gas-phase reactions performed at relatively high temperatures. In the present work, the interface between Pt nanoparticles and a TiN support was modified using a highly dispersed amorphous LaO x phase. The resulting Pt/LaO x /TiO(N) exhibited enhanced activity and long-term stability during the APRM reaction under base-free conditions compared with Pt catalysts supported on unmodified TiN or crystalline La2O3. The interfacial amorphous LaO x phase promoted the deposition of small Pt nanoparticles having a narrow size distribution, and also generated electron-deficient Pt. An assessment of kinetic isotope data and theoretical investigations demonstrated that the cationic Pt nanoparticles facilitated the cleavage of O-H and C-H bonds in methanol while the amorphous LaO x enhanced the dissociation of water, thus enabling the water-gas shift reaction under mild conditions.

High efficiency Al-based multicomponent composites for low-temperature hydrogen production and its hydrolysis mechanism

In this study, a series of multicomponent Al-based composites were prepared by mechanical ball milling of Al powder, low-melting-point metals (Ga, In, Sn), NaCl, g-C3N4 and carbon nanospheres. The composites were thoroughly analyzed using state-of-art characterization techniques with respect to morphologies, structures, chemical compositions, thermal, and electrochemical properties, etc. The hydrogen production performance of Al-based composites has been investigated under three low-temperature conditions, including deionized water (275.15 K), snow-melting agent aqueous solution (253.15–273.15 K), and aqueous electrolyte solutions (KOH, FeCl3, CaCl2, ethylene glycol) at 233.15 K. The best hydrogen production performance with a hydrogen yield of 1133 mL·gAl−1 at 275.15 K and 1095 mL·gAl−1 at 253.15 K was obtained. Especially, no induction time was observed in either condition. Even at 233.15 K in KOH solution, its reaction induction time was around 6 s and final hydrogen yield reached 1057 mL·gAl−1. The observed hydrogen production capabilities of composites have been analyzed and understood in depth, and a tentative multicomponent activation mechanism for low-temperature hydrogen production was proposed as well.

Dimethyl ether low-temperature catalytic oxidation over Rh/Al2O3 in a stagnation-flow reactor

Dimethyl ether (DME) is a promising fuel for use in low-temperature portable hydrogen production, domestic applications, or diesel engines. It burns with less emissions than conventional fuels and has properties similar to LPG in terms of storage and transport, rendering it effective in many strategies for combating climate change. In this study we investigated the partial and total oxidation of DME over 5 wt% Rh/Al2O3 at low temperatures (215 to 320 °C), relevant to portable and domestic energy applications as well as the after-treatment systems of DME-powered engines. We captured the effects of temperature, flow rate, and inlet feed composition on the reactivity. For partial oxidation, we utilized the stagnation-flow reactor geometry to isolate the oxidation zone from the reforming zone. We discuss the reaction order with respect to DME and O2 and provide activation energy values under kinetics control. We also provide data where internal and external mass transfer limitations are present to examine the diffusive-convective transport near the catalyst surface, not easily done in three-dimensional environments such as packed beds. The experimental data we provide here pave the way for accurate kinetic modeling of DME partial and total oxidation on Rh/Al2O3, for reactor design and optimization as well as rational catalyst design.

Non-thermal plasma-assisted steam methane reforming for electrically-driven hydrogen production

Plasma-assisted steam methane reforming (SMR) has become a promising approach for low temperature and small-scale hydrogen production. To increase H2 yields, water-gas-shift reactions are needed to drive the formed CO to CO2 and H2. In this study, bulk gas temperature, plasma power and water feed rate strongly impacted the CO and CO2 product selectivity at high methane conversions of 60–80% in the presence of a Ni-based catalyst. CO2-enriched hydrogen could be formed directly with H2O/methane ratios > 4. To further increase the CO2/CO product selectivity, a “one-pot” cascade design with a Cu/ZnO/Al2O3/MgO catalyst bed placed downstream of the plasma zone achieved substantially higher CO2/CO selectivity (>15) in the effluent gas at 60% methane conversion and 300 °C. Comparably, placing the Cu-based catalyst in the plasma zone does not alter the CO2/CO selectivity. This study highlights the use of plasma reactor systems to directly tune the catalytic SMR performance and lead to an electrified route for hydrogen production.

Low-Temperature Efficient Hydrogen Production from Raw Biomass on the Ni–Mo Catalyst

Low-Temperature Efficient Hydrogen Production from Raw Biomass on the Ni–Mo Catalyst

Enhanced hydrogen production properties of a novel aluminum-based composite for instant on-site hydrogen supply at low temperature

Al-water reaction for hydrogen production faces the problems of long induction time and low conversion efficiency at low temperature (below 273.15 K), which has seriously limited its applications. To realize the instant hydrogen production of Al composites at low temperature, low melting point metals (Ga, In, Sn) and additives (NaCl, g-C3N4, LiH) were selected to prepare Al composites with high reactivity. Compared with the other Al composites, Al alloy/NaCl/LiH/g-C3N4 composites exhibit the enhanced low temperature hydrogen production performance in 23 wt% NaCl aqueous solution at 253.15 K. For all Al alloy/NaCl/LiH/g-C3N4 composites, the induction time of Al-water reaction at 253.15 K has completely eliminated. The highest hydrogen generation volume of 1095 mL·gAl−1 and the maximum hydrogen generation rate of 120 mL·gAl−1·s−1 were obtained for Al alloy/NaCl/1.5%LiH/g-C3N4 composite. It is proposed that LiH can induce Al-water reaction instantly starting at 253.15 K. The released heat and micro alkaline environment further promote the Al-water reaction and enhance the hydrogen conversion efficiency. In particular, g-C3N4 additive can improve the antioxidant properties of Al composites. This study provides a novel way for the development and application of Al composites in real-time hydrogen production at low temperature.

(Invited) Catalysts for Low-Temperature Electrochemical Hydrogen Production and Hydrogenation Reactions

Electrochemical transformation of molecules is not only a low-carbon approach for producing valuable chemicals and fuels, but also a long-duration energy storage solution at scale for renewable power. Materials development especially electrocatalysts plays a critical role in enabling these processes with high efficiency. In this paper, we will present our recent progress on catalyst development for electrochemical hydrogen production and hydrogenation reactions. We will discuss hydrogen evolution reaction (HER) catalysts based on both platinum group metals (PGM) and earth abundant elements in various pH conditions, with a emphasis on the synergy between different components within certain catalysts in hope to reveal new mechanisms for catalyst design and development. We will also discuss electrocatalytic hydrogenation (ECH) of organic molecules from e.g., biomass. From these studies, we observed some correlation between different reactions which may be useful to bridge heterogenous and homogenous electrocatalytic reaction processes and promote catalyst design in both fields.

A stable Cu-polyatomic-cluster catalyst: Critical for methanol reforming deNOx at mild temperature

The practical application of traditional H2-SCR is hindered by its rare hydrogen supply (0.5-2%) and the safety risk of hydrogen transportation and storage. Therefore, this paper proposes a new process to reduce the hydrogen utilization threshold by coupling low-temperature inline hydrogen production and hydrogen deNOx. We synthesized a bifunctional catalyst: Cux/C-MnPdOy@Ni, which could achieve inline hydrogen production above uniformed-dispersion Cu-polyatomic-cluster Cux/C center and coupled with hydrogen deNOx over MnPdOy center. Online-GC monitored the generation of H2 during the process, which confirmed the coupling reaction's feasibility. The candidate Cu800/C-MnPdOy@Ni can maintain over 90% deNOx efficiency at 120 °C under GHSV = 22000 h−1 + water-alcohol ratio (ω) = 1.3 + 800 ppm NO and possessed good water resistance. Through the characterization of morphology and valence state of elements, uniform dispersion of the Cu-polyatomic clusters could directly visualize, which solved the defect of activity site agglomeration; therefore, a more low-temperature hydrogen-producing catalyst was obtained. This article provides a safer H2-SCR process on a coupling catalyst that simultaneously produces in-situ hydrogen and reduces NOx.

Solar-driven low-temperature reforming of methanol into hydrogen via synergetic photo- and thermocatalysis

Low temperature and efficient hydrogen production from methanol is crucial in development of energy technology. Here a synergetic approach of photo- and thermocatalysis of coupling photocatalysis and thermocatalysis within the full spectrum is proposed to achieve efficient conversion of methanol to hydrogen. The composite copper/zinc/zirconium (Cu/Zn/Zr) oxide nanocatalysts are prepared and firstly utilized in synergetic photo- and thermocatalysis. Combine with the effect of the catalyst component and mass ratio on optical absorption, Cu/Zn/Zr (70:23:7) oxide nanocatalysts with full-spectrum absorption have best performance of synergetic photo- and thermocatalysis. Meanwhile, the synergetic photo- and thermocatalysis not only has better performance than either single photocatalysis or thermocatalysis, but also takes place at a relatively low temperature (130 °C). Under irradiation of 16 suns, the solar-chemical conversion efficiency reaches 45.6%. Photo-generated carriers further promote thermocatalysis, which explains the reaction mechanism of the synergetic photo- and thermocatalysis. The catalytic route in full spectrum can provide some references for future energy storage and utilization. • A novel approach of synergetic reforming of methanol into hydrogen is proposed. • The synergetic photo- and thermocatalysis utilizes full-spectrum solar energy. • The synergetic catalysis is superior to single either photocatalysis or thermocatalysis. • The proposed solar-driven reforming approach can be realized at 130 ℃.

Low-temperature hydrogen production from methanol over a ruthenium catalyst in water

Efficient conversion of methanol to hydrogen gas and formate with an appreciably high TOF and TON is achieved over the in situ generated ruthenium catalyst in water at low temperature.

An Al–Li alloy/water system for superior and low-temperature hydrogen production

A superior and low-temperature hydrogen supply technology based on the hydrolysis of an Al–Li alloy was developed.

Biomass-formic acid-hydrogen conversion process with improved sustainability and formic acid yield: Combination of citric acid and mechanocatalytic depolymerization

Sustainable and efficient hydrogen production from biomass resources have been highly desired. Here, we report a low-temperature hydrogen production process from lignocellulosic biomass passing through formic acid (the biomass-formic acid-hydrogen conversion process) with improved sustainability and formic acid yield. In the biomass oxidation/hydrolysis step, toxic sulfuric acid has been replaced by sustainable citric acid. In addition, mechanocatalytic depolymerization of biomass has been applied to the biomass pretreatment step, resulting in the remarkable improvement in formic acid yield. In the first step, the citric-acid-impregnated biomass was subjected to a mechanocatalytic depolymerization process for facilitating contact between the substrate and catalysts (MD-CIB). In the second step, the crude formic acid (CF) solution was obtained via combined hydrolysis-oxidation process of the MD-CIB in the presence of dimethyl sulfoxide (DMSO), and hydrogen peroxide (H2O2). The yield of formic acid were measured up to be 50.03%. In the third step, the lignin-free crude formic acid (LCF) solution was recovered by filtration, or distilled formic acid (DF) solution was obtained by distillation of the CF solution. In the final step, hydrogen was generated from LCF or DF solutions through dehydrogenation of formic acid over Pd catalysts supported on amine-functionalized mesoporous silica (KIE-6) with a sodium formate. The turnover frequency (TOF) at 10 min were measured up to be 279.24 mol H2 mol Pd-1h−1. The clean hydrogen, which is produced from biomass passing through formic acid, could be directly applied in fuel cell as an energy source. Our hydrogen production process is expected to be much more efficient, sustainable and economical process for hydrogen production from biomass. In addition, organic acids as a byproduct could be utilized as a platform chemical.

Low-temperature hydrogen production from methanol steam reforming on Zn-modified Pt/MoC catalysts

Methanol steam reforming (MSR) is a promising process to produce hydrogen suitable for polymer electrolyte membrane fuel cells, but the development of catalysts with high activity and selectivity at low temperature is highly needed. Here, a series of Zn-modified Pt/MoC catalysts with different Zn loadings were prepared and used to produce hydrogen by MSR at low temperature. The addition of small amounts of Zn to Pt/MoC not only favors the formation of α-MoC1-x phase, but also enhances the Pt dispersion and the interaction between α-MoC1-x and Pt active sites, leading to increased catalytic activity for MSR. The optimal 0.5Zn-Pt/MoC catalyst exhibits superior hydrogen production activity with exceptionally low CO selectivity at low temperatures (120–200 °C). Overall, this work offers insight into the structure-activity relationship and stability in Zn-modified Pt/MoC catalysts for MSR, which will be helpful to the design of MSR catalysts with high activity and stability at low temperature.

Low Temperature Hydrogen Production by Ethanol Steam Reforming over Supported Metal Catalysts in an Electric Field

The use of catalytic steam reforming for direct hydrogen production from biomass-derived ethanol is attracting much attention. Herein, we report a novel electrocatalytic reaction system, catalytic reaction in an electric field, for low-temperature catalytic ethanol steam reforming using low-grade waste heat. Application of an electric field to Pt/CeO2 catalyst enables the reaction to proceed even at 423 K, at which a conventional catalytic reaction only slightly proceeded. Results of activity tests conducted using isotopes indicate that the electric field contributed to activation of the adsorbed OHx species. In-situ DRIFTS measurements revealed that an electric field promoted the formation of reactive adsorbed intermediate acetate species and showed that the steam reforming reaction of the formed acetate species proceeded even at low temperatures. Results show that ethanol steam reforming proceeded efficiently in the electric field at low temperatures. In this electrocatalytic reaction system, hydrogen was produced efficiently from ethanol using less electricity, even at low temperature.