Hydrogen Formation Rate Research Articles

Plastics-to-syngas photocatalysed by Co-Ga2O3 nanosheets.

ABSTRACTPlastics take hundreds of years to degrade naturally, while their chemical degradation typically requires high temperature and pressure. Here, we first utilize solar energy to realize the sustainable and efficient plastic-to-syngas conversion with the aid of water at ambient conditions. As an example, the commercial plastic bags could be efficiently photoconverted into renewable syngas by Co–Ga2O3 nanosheets, with hydrogen and carbon monoxide formation rates of 647.8 and 158.3 μmol g−1 h−1. In situ characterizations and labelling experiments unveil water is photoreduced into hydrogen, while non-recyclable plastics including polyethylene bags, polypropylene boxes and polyethylene terephthalate bottles are photodegraded into carbon dioxide, which is further selectively photoreduced into carbon monoxide. In-depth investigation illustrates that the efficiency of syngas production mainly depends on the carbon dioxide reduction process and hence photocatalysts of high carbon dioxide reduction activity should be designed to promote the efficiency of plastic-to-syngas conversion in the future. The concept for the photoreforming of non-recyclable plastics into renewable syngas helps to eradicate ‘white pollution’ and alleviate the energy crisis simultaneously.

Mg and Cu incorporated CoFe2O4 catalyst: characterization and methane cracking performance for hydrogen and nano-carbon production

The Cobalt ferrite (CoFe2O4) and cobalt ferrite incorporated with Cu (Cu–CoFe2O4) and Mg (Mg–CoFe2O4) have been synthesized by wet chemical route. In fixed-bed reactor, the CoFe2O4, Cu–CoFe2O4 and Mg–CoFe2O4 were used as catalysts for direct cracking of methane at temperature of 800 °C and 20 mL/min of feed gas flow rate for hydrogen and nano-carbon production. Different characterizations techniques namely XRD, FESEM, XPS, Raman spectroscopy, TGA, BET for fresh and spent catalysts have been executed. The X-ray powder diffraction and Raman spectra confirmed that the fresh catalysts possess a cubic spinel crystal structure. The FESEM images for spent catalysts displayed that filamentous carbons were not formed over catalysts surfaces except a few amount was observed over the spent CoFe2O4 catalyst. XPS results confirmed the purity of the synthesized catalysts and qualitatively evaluate the cation distribution between the tetrahedral and octahedral sites from Co 2p3/2 and Fe 2p3/2 spectra. BET surface area revealed no significant effects in surface area and pore size of CoFe2O4 catalyst by incorporation of Mg and Cu metals. Activity studies showed that incorporation Mg metal on CoFe2O4 improved methane conversion up to 40.03% and hydrogen formation rate of 79.90 mol H2 g−1 min−1 as compared to 31.61% and 66 mol H2 g−1 min−1 for CoFe2O4 catalyst. Whilst, Cu metal incorporation in CoFe2O4 catalyst led to decline the catalyst performance. Structure activity relationship was described in details.

Gamma rays mediated water splitting on nano-ZrO2 surface: Kinetics of molecular hydrogen formation

Hydrogen generation by water splitting is reported in nano-ZrO2+H2Oabs. and nano-ZrO2+H2Oflu. systems using gamma radiation at different ZrO2 particle sizes (50–70 nm) and temperatures (300–673K). The rates of molecular hydrogen (H2) formation in radiolysis process were studied in radiation-chemical process using γ-quanta (60Co, D = 0.26–0.22 Gy/s, T = 300–673K, 50–70 nm) with mZrO2 = 3 × 10−2 g, 0.5 mL water. The energy yield of molecular hydrogen in radiation-heterogeneous processes in both nano-ZrO2+H2Oabs. and nano-ZrO2+H2Oflu. systems increased as the particle size of nano-ZrO2 decreased. The temperature stimulated the process of heterogeneous radiolysis during radiation-heterogeneous processes in n-ZrО2+Н2Оabs. system in the range of 300–673K. The molecular hydrogen (H2) yield increased linearly with temperature from 1.57 to 19.6 molecules/100 eV for d = 50–70 nm of particle size. The contributions of thermal and radiation-thermal processes to the accumulation of molecular hydrogen (H2) in the contact of n-ZrO2 with water was revealed [1.57–19.6 molecules/100eV(50–70 nm)] and the activation energy of the processes of molecular hydrogen formation was 21.2 kJ/mol (50–70 nm) radiation-thermal processes and 28.8 (50–70 nm) kJ/mol thermal processes. Briefly, molecular hydrogen contents in the nano-ZrO2+H2Oflu. system; where nano-ZrO2 was in a water-soluble state, and the yield of molecular hydrogen for gamma rays (molecule/100eV) absorbed by 100 eV absorption; was 6.0–6.5 (50–70 nm) times higher than the n-ZrO2+H2Oabs. system. These results are promising for molecular hydrogen generation by water splitting in near future.

Pd Supported on ZSM-5 with different ratios of Si/Al as catalysts for direct catalytic decomposition of methane

Hydrogen and filamentous carbon have been produced by direct catalytic decomposition of methane. ZSM-5 Zeolite with ratios of Si/Al (25, 140, and 750) was used as a support in 0.5 wt% Pd/ZSM-5 catalysts. Fresh and spent Pd/ZSM-5 catalysts were characterized by XRD, SEM, TGA and CHN analyses. The hydrogen formation rates for the catalysts were Pd/ZSM-5 (25) < Pd/ZSM-5 (140) < Pd/ZSM-5 (750). The CHN analysis showed wt% of the carbon that was deposited, over the catalysts, during the reaction run to be 15.6, 17.1, and 34.3 for Pd/ZSM-5 (25), Pd/ZSM-5 (140), and Pd/ZSM-5 (750), respectively. The SEM images revealed that filamentous carbon was produced. It appears that the zeolite support in different Si/Al ratios led to form different sizes of palladium particles and palladium dispersion over ZSM-5 support. It is suggested that the catalyst activity be ascribed to the palladium particles size and its dispersion over ZSM-5.

One-pot synthesis of supported Ni@Al2O3 catalysts with uniform small-sized Ni for hydrogen generation via ammonia decomposition

Nickel based materials are the most potential catalysts for COx-free hydrogen production from ammonia decomposition. However, the facile synthesis of supported Ni-based catalysts with small size Ni particles, high porosity and good structural stability is still of great demand. In this work, uniform small-sized Ni particles supported into porous alumina matrix (Ni@Al2O3) are synthesized by a simple one-pot method and used for ammonia decomposition. The Ni content is controlled from 5 at.% to 25 at.%. Especailly, the 25Ni@Al2O3 catalyst shows the best catalytic performance. With a GHSV of 24,000 cm3gcat−1h−1, 93.9% NH3 conversion is achieved at 600 °C and nearly full conversion of NH3 is realized at 650 °C. The hydrogen formation rate of 25NiAl catalyst reaches 3.6 mmol gcat−1min−1 at 400 °C and 7.8 mmol gcat−1min−1 at 450 °C. The enhanced activity observed on 25Ni@Al2O3 catalyst can be attributed to the structural characteristic that large amounts of uniform-sized small (7.2 ± 0.9 nm) Ni particles are highly dispersed into porous alumina matrix. The aggregation of active metallic Ni particles during the high temperature reaction can be effectively prevented by the porous alumina matrix due to the strong interaction between them, thus ensuring a good catalytic performance.

THE INFLUENCE OF MASS AND SIZE EFFECTS ON THE RADIOLYSIS PROCESS OF WATER IN THE BeO/H2O SUSPENDED SYSTEM BY THE GAMMA-QUANTA

The amount, formation rate and radiation-chemical yield of molecular hydrogen obtained from water radiolysis process within the system, have been defined according to both water and BeO by maintaining the water volume constant (V = 5 ml); by changing the mass (mBeO= 0.0 (pure water), 0.01; 0.02; 0.04; 0.08; 0.2 g) and particle size (d &lt; 4, d = 32…53 and 75…106 μm) of beryllium oxide in the porous BeO/H2O suspended systems by the influence of γ-quanta (60Co, P = 19.5 rad/s, T = 300 K). It has been established that the amount, formation rate and radiation-chemical yield of molecular hydrogen defined according to both water and BeO from radiation-heterogeneous transformation of water in these systems, change depending on mass and particle size of BeO added to water.

Influence of space velocity and catalyst pretreatment on COx free hydrogen and carbon nanotubes production over CoMo/MgO catalyst

The influence of catalyst pretreatment and space velocity in methane decomposition into COx-free hydrogen and carbon nanotubes were investigated over CoMo/MgO catalyst. The reduction of catalyst before methane decomposition leads to a hydrogen production without significant formation of COx (concentration lower than 5 ppm after 25 min of reaction) suitable for its use in fuel cells. However, a high hydrogen space velocity in the pretreatment increased the rate of catalyst deactivation. The CO and CO2 formation rates showed a common trend for all conditions tested: there was a high initial rate and, after 2 min of reaction, there was a lower stabilized rate. The increase in methane space velocity increased the hydrogen formation rate and the degree of carbon nanotubes graphitization. However, it strongly decreases methane conversion, as expected. The use of low hydrogen space velocity, 0.25 h−1, in catalyst pretreatment and high methane space velocity, 8 h−1, in reaction step, provided the highest hydrogen yield and well-structured carbon nanotubes.

Mechanism of Ethanol Conversion on a 5% CuO/ZrO2 Catalyst According to In Situ IR-Spectroscopic Data

Ethoxy groups, acetate complexes, and condensation products were detected on the surface of a 5% CuO/ZrO2 catalyst using in situ IR spectroscopy under conditions of ethanol conversion. Formate complexes were not observed under the reaction conditions. Acetaldehyde, acetone, CO2, and ethylene were detected as the main reaction products of ethanol conversion; hydrogen, butane, and toluene were also formed in small amounts. Acetaldehyde was formed by the interaction of ethoxy groups and surface hydroxyl groups. Acetone, butane, and toluene resulted from the conversion of condensation products. The low rate of hydrogen formation on this catalyst was due to the absence of a high-temperature formate complex from the catalyst surface.

Photocatalytic Decomposition of Water on S,N-Doped Semiconductor NiO–TiO2 Oxides

Three types of composite photocatalysts synthesized by the sol-gel method and doped with sulfur and nitrogen were considered. The factors influencing the structure formation and properties of active sites on the catalysts based on hybrid nickel-titanium oxide systems promoted by sulfur and nitrogen in the production of hydrogen from water were studied. The conditions of preparation were established to have an essential effect on the physicochemical and catalytic properties of the synthesized materials. The introduction of NiO into the structure of TiO2 was demonstrated to increase its photocatalytic activity in the production of hydrogen from a methanol–water mixture. Doping with nitrogen and sulfur also improved the catalytic activity of the synthesized catalysts. The mechanism of charge transfer in the photocatalytic Ti(IV)–O–Ni(II) system under visible light irradiation was revealed. The existence of so-called p–n junctions in these complex oxide systems was shown, and the limits of their application were determined. The dependence between the number of photocatalytic sites and their activity in the destruction reaction of water-soluble organic compounds was revealed. This process was controlled by such factors as the concentration of organic compounds, the catalyst amount, and pH of the reaction medium. The optimal concentration of a catalyst in the studied systems was estimated as 1 g/dm3. The highest hydrogen formation rate was observed at pH ~ 7 close to the pH value at the zero charge point of the titanium dioxide surface. A new approach to the synthesis of photocatalysts was proposed, thus opening up additional opportunities in the development of heterostructures for the photocatalytic conversion of solar energy and the production of hydrogen fuel.

NiMgAlMo catalyst derived from a guest-host MoO42- mediated layered double hydroxide: High performance for the methane decomposition reaction

The synthesis of highly active and stable Ni catalysts for the catalytic decomposition of methane (CDM) reaction is still a challenge. Herein, a MoO42− intercalated NiMgAlMo layered double hydrotalcite (LDH) was synthesized. After calcination and reduction, NiMo alloy particles with an average diameter of 7.4 nm were formed and showed good thermal stability. The NiMgAlMo-800 catalyst showed superior hydrogen formation rate of 56 mmol/gNi min compared with the NiMgAl-800 catalyst of 33 mmol/gNi min derived from NiMgAl-LDH. The stability of the NiMgAlMo-800 catalyst showed good catalytic stability under 10 times reaction-regeneration cycles. With the aid of multiple characterization techniques, we found that Mo addition could not only improve nickel dispersibility but also facilitate methane adsorption and hydrogen desorption through simulative electron transfer from Mo to Ni, thus enhancing the catalyst activity. The insights and methodology presented here may shed new light on the synthesis of highly dispersed and stable metal catalysts.

Zr–Ce-incorporated Ni/SBA-15 catalyst for high-temperature water gas shift reaction: Methane suppression by incorporated Zr and Ce

SBA-15 supports with incorporated Zr and/or Ce were synthesized using direct hydrothermal synthesis, followed by ammonia evaporation to prepare Ni–phyllosilicate-derived catalysts. The effect of zirconium and cerium ions present in the silica framework in catalyzing the high-temperature water–gas shift (WGS) reaction and circumventing the undesired methanation reaction was investigated over the temperature range from 250 to 500 °C. Diffuse-reflectance infrared Fourier transform spectroscopy revealed that surface hydroxyl species on silica were involved in promoting WGS activity for all catalysts. Furthermore, the presence of Zr and Ce in the silica framework could minimize the formation of Ni subcarbonyl species and enhance the adsorption of CO on Ni. At 375 °C, the Ni/Zr–Ce-SBA-15 catalyst achieved excellent catalytic activity in the WGS reaction in terms of turnover frequency (4.57 s−1) and hydrogen formation rate (534 μmol H2 g−1s−1). A dual-site carboxyl mechanism was proposed to be the plausible pathway over the Ni/Zr–Ce-SBA-15 catalyst.

Prevention of substrate and product inhibitions by using a dilution strategy during dark fermentative hydrogen production from molasses

Substrate and product inhibitions have a significant effect on dark fermentative hydrogen gas production. Particularly, rapid formation of volatile fatty acids leads to fast pH decreases shifting the metabolic pathway. Therefore, controlling volatile fatty acid accumulation has great importance in maintaining effective hydrogen production. In this context, a dilution strategy was applied to regulate volatile fatty acids levels within the desired concentration range. A three-factor Box-Behnken statistical experiment design was established to assess the effects of dilution time, dilution percentage and initial COD concentration on hydrogen formation yield and rate. Highest hydrogen yield (7.7 mL H2/mLreactor) and rate (21. 47 mL H2/h or 9.38 mmol/Lreactor.h) were achieved when 85 gCOD/L containing fermentation media was diluted with a percentage of 130 of the initial working volume at the 3rd hour of the fermentation period. Moreover, this strategy enabled to start fermentation with 55 g glucose/L.

Reactive metal-support interaction in the Cu-In2O3 system: intermetallic compound formation and its consequences for CO2-selective methanol steam reforming

ABSTRACT The reactive metal-support interaction in the Cu-In2O3 system and its implications on the CO2 selectivity in methanol steam reforming (MSR) have been assessed using nanosized Cu particles on a powdered cubic In2O3 support. Reduction in hydrogen at 300 °C resulted in the formation of metallic Cu particles on In2O3. This system already represents a highly CO2-selective MSR catalyst with ~93% selectivity, but only 56% methanol conversion and a maximum H2 formation rate of 1.3 µmol gCu −1 s−1. After reduction at 400 °C, the system enters an In2O3-supported intermetallic compound state with Cu2In as the majority phase. Cu2In exhibits markedly different self-activating properties at equally pronounced CO2 selectivities between 92% and 94%. A methanol conversion improvement from roughly 64% to 84% accompanied by an increase in the maximum hydrogen formation rate from 1.8 to 3.8 µmol gCu −1 s−1 has been observed from the first to the fourth consecutive runs. The presented results directly show the prospective properties of a new class of Cu-based intermetallic materials, beneficially combining the MSR properties of the catalyst’s constituents Cu and In2O3. In essence, the results also open up the pathway to in-depth development of potentially CO2-selective bulk intermetallic Cu-In compounds with well-defined stoichiometry in MSR.

Studying the Mechanism of the Low-Temperature Oxidation of Microsized Aluminum Powder by Water

The mechanism of the oxidation of disperse aluminum (powder of ASD-4 grade) by liquid water was studied including the use of different process activation methods (thermal, ultrasonic, and chemical in the presence of small CaO amounts). For this purpose, the complex study of the aluminum oxidation process was performed at its different stages by analyzing the kinetic dependences of the hydrogen formation rate and the reaction medium pH change and using the instrumental methods of scanning electron microscopy and X-ray diffraction analysis. It has been demonstrated that the shape of kinetic hydrogen release curves, the oxidation process completeness, and the structure of formed hydroxides are interrelated. An essential role is played by the mass transfer of formed solid oxidation products from the surface of particles to the crystallization nuclei of aluminum hydroxide and the localization of crystallization areas. This work is topical because of the broad interest in the use of metallic aluminum as an energy-accumulating substance.

Photocatalytic evolution of H2 from aqueous solutions of two-component electron-donor substrates in the presence of g-C3N4 activated by heat treatment in the KCl + LiCl melt

It has been shown that post-synthetic heat treatment of g-C3N4 in the melt of potassium and lithium salts leads to a significant increase of photocatalytic activity in the hydrogen formation from aqueous solutions of electron-donor compounds compared to the initial g-C3N4. This could be explained in terms of formation more crystalline graphitic carbon nitride (CGCN) with enhanced ability for absorption of higher amounts of visible light. Simultaneously, this treatment significantly decreases level of electron-hole recombination. It has been established that coincident use of two donors of different nature (organic acid and alcohol) with CGCN significantly increases rate of hydrogen formation. The possible explanation to this phenomenon could be find within acidic activation of CGCN. The influence of a number of factors on the efficiency of photocatalytic hydrogen production under visible light in systems based on the received carbon nitride has been investigated. The apparent quantum yields of the hydrogen evolution process with use of CGCN were determined as 23.6 and 5.6% at 405 and 435 nm, respectively.

Mechanistic study of liquid phase glycerol hydrodeoxygenation with in-situ generated hydrogen

The mechanism of the liquid phase glycerol hydrodeoxygenation–methanol reforming tandem reaction cycle over a Cu:Zn:Al catalyst is investigated. The hydrogen needed is provided in-situ via methanol reforming. In–situ DRIFTS of adsorbed methanol proved that methanol reforming proceeds via sequential methanol dehydrogenation to CO and further conversion to CO2 via water gas shift reaction. High hydrogen formation rate is achieved by increasing methanol to glycerol molar ratio. The elucidation of reaction pathways using mechanistic tests and in-situ IR spectroscopy showed that the first step of glycerol hydrodeoxygenation depends on hydrogen availability. Glycerol hydrodeoxygenation proceeds mainly via dehydration-hydrogenation route with hydroxyacetone as the main intermediate product. However at low methanol/glycerol molar ratio, the simultaneous formation of 1,2-propanediol via glyceraldehyde route cannot be excluded. 1,2-propanediol is stable product with low rate of further hydrodeoxygenation to 1-propanol. Though at low selectivities, ethylene glycol is the main degradation byproduct formed via direct hydrogenolysis of glycerol.

A Novel Shewanella Isolate Enhances Corrosion by Using Metallic Iron as the Electron Donor with Fumarate as the Electron Acceptor.

The involvement of Shewanella spp. in biocorrosion is often attributed to their Fe(III)-reducing properties, but they could also affect corrosion by using metallic iron as an electron donor. Previously, we isolated Shewanella strain 4t3-1-2LB from an acetogenic community enriched with Fe(0) as the sole electron donor. Here, we investigated its use of Fe(0) as an electron donor with fumarate as an electron acceptor and explored its corrosion-enhancing mechanism. Without Fe(0), strain 4t3-1-2LB fermented fumarate to succinate and CO2, as was shown by the reaction stoichiometry and pH. With Fe(0), strain 4t3-1-2LB completely reduced fumarate to succinate and increased the Fe(0) corrosion rate (7.0 ± 0.6)-fold in comparison to that of abiotic controls (based on the succinate-versus-abiotic hydrogen formation rate). Fumarate reduction by strain 4t3-1-2LB was, at least in part, supported by chemical hydrogen formation on Fe(0). Filter-sterilized spent medium increased the hydrogen generation rate only 1.5-fold, and thus extracellular hydrogenase enzymes appear to be insufficient to explain the enhanced corrosion rate. Electrochemical measurements suggested that strain 4t3-1-2LB did not excrete dissolved redox mediators. Exchanging the medium and scanning electron microscopy (SEM) imaging indicated that cells were attached to Fe(0). It is possible that strain 4t3-1-2LB used a direct mechanism to withdraw electrons from Fe(0) or favored chemical hydrogen formation on Fe(0) through maintaining low hydrogen concentrations. In coculture with an Acetobacterium strain, strain 4t3-1-2LB did not enhance acetogenesis from Fe(0). This work describes a strong corrosion enhancement by a Shewanella strain through its use of Fe(0) as an electron donor and provides insights into its corrosion-enhancing mechanism.IMPORTANCEShewanella spp. are frequently found on corroded metal structures. Their role in microbial influenced corrosion has been attributed mainly to their Fe(III)-reducing properties and, therefore, has been studied with the addition of an electron donor (lactate). Shewanella spp., however, can also use solid electron donors, such as cathodes and potentially Fe(0). In this work, we show that the electron acceptor fumarate supported the use of Fe(0) as the electron donor by Shewanella strain 4t3-1-2LB, which caused a (7.0 ± 0.6)-fold increase of the corrosion rate. The corrosion-enhancing mechanism likely involved cell surface-associated components in direct contact with the Fe(0) surface or maintenance of low hydrogen levels by attached cells, thereby favoring chemical hydrogen formation by Fe(0). This work sheds new light on the role of Shewanella spp. in biocorrosion, while the insights into the corrosion-enhancing mechanism contribute to the understanding of extracellular electron uptake processes.

Hydrogen Production by Water Decomposition through Redox Reaction of Ce-based Metal Oxide Systems in Electric Field

We investigated a highly active hydrogen production system by decomposition of water through the redox reaction of metal oxide at 623 K in an electric field (EF). Although Ce0.67Cr0.33O2 oxide showed high activity in the EF for oxygen release with the formation of lattice oxygen defects, it showed no hydrogen production activity by the regeneration of lattice oxygen defects with water. However, addition of Pd into the Ce0.67Cr0.33O2 structure promoted the hydrogen formation rate while maintaining its oxygen release activity. Results of optimization of the doping Pd amount demonstrated that 5 mol% Pd-doped oxide (Ce0.62Cr0.33Pd0.05O2) had the highest oxygen release rate and hydrogen formation rate. Doped Pd contributes to lattice strain induction and thereby increases the reaction rates.

Enhanced photocatalytic hydrogen formation over Fe-loaded TiO2 and g-C3N4 composites from mixed glycerol and water by solar irradiation

Fe-doped TiO2 with various levels of Fe (0.5, 1, 2, 3, and 5 wt. %) was made via impregnation, and the Fe-doped TiO2 catalysts were modified with g-C3N4. These materials were studied using FE-SEM, Uv-DRS, TEM, Raman, FT-IR, and XPS techniques. The results show that the fine dispersed Fe3+ and g-C3N4 expanded the photoresponse of titania into the visible region on the introduction of ferric ions and fine dispersion of g-C3N4 on TiO2. The hydrogen formation rate from solar light-induced photocatalysis can be greatly increased by coupling g-C3N4 with the above Fe-doped TiO2, and the 1 wt. % Fe-modified TiO2 with the g-C3N4 composite has high photoactivity and shows excellent photostability for hydrogen production by solar irradiation. The stable hydrogen evolution of 1 wt. % Fe-doped TiO2 with g-C3N4 is some 17 times higher than that found with unmodified TiO2. The results show that the photogenerated electrons of g-C3N4 can directionally migrate to Fe-doped TiO2 due to intimate interfacial contacts and synergism operating between Fe-doped TiO2 and g-C3N4 where photogenerated electrons and holes are efficiently spatially separated. This separation retards the charge recombination rate and improves photoactivity.

Hydrogen Gas Production from Waste Peach Pulp by Natural Microflora

Dark fermentative hydrogen gas production from waste peach pulp was studied without external microbial culture inoculation. First, most suitable pulp concentration for hydrogen production was determined in bench scale serum bottles then a 140 L pilot scale reactor was operated at most convenient pulp concentration. During the bench scale experiments the pulp concentration was varied between 3.42 and 170.80 g TS/L and the highest cumulative hydrogen volumes were obtained at 102.5 and 170.8 g TS/L, respectively. The initial pulp concentration of 34.16 g TS/L showed the best performance in terms of hydrogen formation yield (180 mL H2/g COD) and rate (6.44 mL H2/h). Hydrogen yield and rate increased up to 34.16 g TS/L due to substrate limitation. However, higher pulp concentrations resulted in substrate inhibition. This result was in accordance with the kinetic analysis where the substrate inhibition constant was determined as 43.86 g TS/L. The pilot scale reactor operated at optimum 34.16 g TS/L pulp concentration resulted in 323.67 mL H2/g COD and 3900 mL H2/h hydrogen formation, respectively. Our results demonstrated that waste peach pulp could be used both as substrate and inoculum source for hydrogen gas production when the initial substrate concentration is adjusted properly.