Feedstock For Hydrogen Production Research Articles

Advances in the Homogeneously Catalyzed Hydrogen Production from Biomass Derived Feedstocks: a Review.

Biomass‐derived feedstocks for hydrogen production are crucial as an alternative to fossil fuel especially in those areas where green electricity and clean water are scarce. In this framework the transformation of simple (formic acid, alcohols) and more complex (polyalcohols, sugars and cellulose) bio‐derivatives in pure hydrogen is recognized as a promising approach. Parallel to great effort in heterogeneous catalysis, milder molecular systems represent a more selective eye for alternative solutions and mechanistic insights. In the present review the introduction summarizes the challenges in the catalytic utilization of biomass‐derived feedstocks, followed by the advances in homogeneously catalyzed hydrogen production from different substrates which will cover formic acid, with oustanding efficiency with noble metals and promising results with earth abundant ones and alcohols and polyalcohols, with particular emphasis to the development of heterogenized systems, ligand assisted catalysts and bi‐catalytic synergistic solutions which allow to avoid base and to promote catalyst stability and recyclability. In the last part, description of hydrogen production from more complex substrates, such as sugars and cellulose, will show the role of molecular complexes in main and side reactions. Critical comments on the reported advances are provided along the whole discussion.

Microbial activity of lactic acid bacteria and hydrogen producers mediated by pH and total solids during the consolidated bioprocessing of agave bagasse

Lactic acid bacteria (LAB) coexist with Clostridium spp. in hydrogen production processes from complex substrates; however, the role of LAB is still unclear. This study analyzed the fermentation products in a wide range of initial pH (pHi, 5.5–6.9) and total solids (TS%, 8–22%) to determine the activity of these two microbial groups over time (from 24 to 120 h). Agave bagasse served as the feedstock for hydrogen production via consolidated bioprocess (CBP), while the inoculum source was the indigenous mature microbiota. In the early stage of the CBP, hydrogen production from lactic acid occurred only at pHi ≥ 6.0 (ρ = 0.0004) with no effect of TS%; lactic acid accumulated below this pHi value. In this stage, lactic acid production positively correlated with a first cluster of LAB represented by Paucilactobacillus (r = 0.64) and Bacillus (r = 0.81). After 72 h, hydrogen production positively correlated with a second group of LAB led by Enterococcus (r = 0.71) together with the hydrogen producer Clostridium sensu stricto 1 (r = 0.8) and the acetogen Syntrophococcus (r = 0.52) with the influence of TS% (ρ < 0.0001). A further experiment showed that buffering the pH to 6.5 increased and lengthened the lactic acid production, doubling the hydrogen production from 20 to 41 mL H2/gTSadded. This study confirmed the prevalence of distinct groups of LAB over time, whose microbial activity promoted different routes of hydrogen production.

Steam reforming of n-butanol and tetrahydrofuran: Influence of aliphatic carbon chain and furan ring on coking behaviors

Almost all small organics, in theory, could be potential feedstock for production of hydrogen via steam reforming (SR). Nevertheless, not all organics contain a linear carbon chain like ethanol or acetone. How do ring structure of an organic substrate impacted coking behaviors in SR were explored herein with n-butanol and tetrahydrofuran (THF) as the research objects over Ni/SiO2 catalyst, due to the same carbon number but distinct carbon chains in these two molecules. The results indicated that furan ring in THF lowered reactivity towards SR, as its adsorption on metallic sites was more difficult than n-butanol. The in-situ IR analysis for measuring reaction intermediates suggested that n-butanol and THF involved generation of intermediates with CO formed via dehydrogenation, CxHy formed via cracking and CC species that can be further gasified or aggregate to coke. However, more oxygenated intermediates generated in SR of n-butanol than in THF, rendering n-butanol more reactive towards SR. This, however, also formed substantially more coke of aliphatic nature in amorphous form, which led to the coke of thermally unstable and had higher tendency being oxidized. In converse, coke formed from SR of THF was more aromatic, showing less impact on catalytic activity, higher thermal stability, and larger crystal size with more carbon nanotube form of coke. This was closely connected with the ring structures that could dehydrogenated to form the unsaturated ring with capability to involve in Diels-Alder reactions, forming coke of aromatic nature.

Design and exergy analysis of highly efficient chemical looping reforming processes of coking dry gas in double and triple reactors

Coking dry gas is a kind of refinery dry gas, which can be used as a feedstock for hydrogen production, but its steam reforming has the problems of high energy penalty and CO2 emissions. Therefore, novel processes of coking dry gas chemical looping reforming to produce CO and H2 using Fe-Cu as oxygen carrier were proposed in this study. Firstly, two processes of two-reactor for syngas production and three-reactor for syngas-high purity hydrogen production using external-heating were designed and the effects of the temperature difference between fuel and air reactor and the heat carrier addition were studied. When the temperature difference is increased to 150 °C, the exergy efficiencies of the two processes are 70.87 % and 77.13 % and the fuel reactors both produce 2.21 kmol syngas per kmol dry gas. While the inclusion of a steam reactor in the three-reactor system generates an additional 0.61 kmol high-purity hydrogen per kmol dry gas, thereby achieving higher efficiency compared to the two-reactor system. Heat carrier was used to fully transfer the heat from the air reactor to fuel reactor to obtain two auto-thermal systems. Their exergy efficiencies are as high as 84.39 % and 84.58 % and the fuel reactors both produce 3.02 kmol syngas/kmol dry gas, while the high-purity hydrogen production of three-reactor auto-thermal system is only 0.05 kmol/kmol dry gas. Obviously, the external-heating three-reactor process has notable advantages compared to the two-reactor. For auto-thermal systems, this work suggests developing high-temperature resistant Fe-Cu composite oxygen carriers and heat carriers with larger heat capacity to decrease the usage of heat carriers.

Valorization of microalgae oil via steam reforming for hydrogen-rich gas production over Ni/CeO2-ZrO2

This study investigated the steam reforming of microalgae oil in the existence of Ni/CeO2-ZrO2 catalyst to assess its potential for hydrogen production. For this purpose, the catalyst was synthesized by the impregnation-co-precipitation method and characterized using various techniques. Catalytic microalgae steam reforming was performed in a continuous flow quartz fixed bed reactor and the effects of reaction temperature, weight hourly space velocity, and steam to microalgae volume ratio on conversion and hydrogen selectivity were evaluated. The findings revealed that microalgae oil, especially with a high oleic acid content, showed promise as a feedstock for hydrogen production via steam reforming. Suitable conditions were identified as a reaction temperature of 850 °C, weight hourly space velocity of 29 h−1, and steam to microalgae oil volume ratio of 12:1, resulting in 99.79 % hydrogen selectivity and 100 % microalgae oil conversion. Furthermore, a characterization of the spent catalyst was conducted, and a coke deposition of 19.17 mgcarbon/gcat.h was observed following 15 h of reaction.

Modeling and analysis for enhanced hydrogen production in process simulation of methanol reforming

ABSTRACT Hydrogen has emerged as the most suitable fuel for a nation’s greener and sustainable development. In contrast, the feedstock and hydrogen production methods remain a concern for environmental pollution. This study uses methanol as the feedstock for hydrogen production via a low-temperature methanol-reforming process. A simulation model was developed in Aspen Hysys, where an equilibrium reactor is used in the reforming process, and examined the effects of parameters like temperature, pressure, and Methanol-to-Water (M-to-W) molar ratio. Hydrogen mole fraction and selectivity increase by roughly 18.5% and 10.5% when the reaction temperature increases from 100°C to 400°C. At the same time, the methanol conversion rate reaches 95% at 400°C. Reactor pressure shows inverse effects where pressure rises from 1 atm. to 7 atm. that reduces hydrogen mole fraction and selectivity by about 10% and 6%, and a similar reduction of 5% is noticed in the methanol conversion rate. M-to-W molar ratio plays a crucial role in the reaction pathway and the M-to-W ratio between 0.5 and 1.5 at 400°C and 1 atm. reactor pressure showed the highest hydrogen mole fraction (>0.57) and a maximum methanol conversion rate (>90%). Therefore, the present simulation model successfully determines the impacts of various parameters to help design a commercial plant for large-scale hydrogen production via the reforming process.

Vine shoots pre-treatment strategies for improved hydrogen production and metabolites redistribution in Clostridium butyricum

This work deals with the use of vine shoots, a renewable, largely available, lacking of alternatives lignocellulosic material as a feedstock for hydrogen production. Physical pre-treatments by steam explosion (SE), chemical by organosolv (OS) and biological by laccase (LAC) were carried out in vine shoots to disrupt the cell fiber and increase the biomass hydrolysis and fermentation into hydrogen (H2). After SE, there was a slight decrease in cellulose and hemicellulose contents in biomass fibers, while a decrease in lignin content occurred after OS pre-treatment. There were no quantifiable changes after laccase pre-treatment, however the enzyme-substrate oxidative reactions were favorable for hydrolysis and fermentation since an increase in soluble sugars and H2 production was observed with LAC vine shoots as substrate. 300.1 mL H2/L were obtained from raw material vine shoots, while 649.4, 399.8 and 749.7 mL H2/L were obtained from biomass pre-treated by SE, OS and LAC, respectively. Furthermore, the hydrolysis of pre-treated biomass by addition of cellulase was evaluated to improve H2 production. Higher amounts of H2 were obtained from hydrolyzed biomass in relation to non-hydrolyzed ones (154.2%, 602.0% and 167.1% more with SE, OS and LAC hydrolyzed, respectively). In all cases, the mixed acid pathway was carried out by Clostridium butyricum, since acetic and butyric acids were produced.

Comment on “Climate consequences of hydrogen emissions” by Ocko and Hamburg (2022)

Abstract. In this commentary, we provide additional context for Ocko and Hamburg (2022) related to the climate consequences of replacing fossil fuels with clean hydrogen alternatives. We first provide a tutorial for the derivations of underlying differential equations that describe the radiative forcing of hydrogen emissions, which differ slightly from equations relied on by previous studies. Ocko and Hamburg (2022) defined a metric based on time-integrated radiative forcing from continuous emissions. To complement their analysis, we further present results for temperature and radiative forcing over the next centuries for unit pulse and continuous emissions scenarios. Our results are qualitatively consistent with previous studies, including Ocko and Hamburg (2022). Our results clearly show that for the same quantity of emissions, hydrogen shows a consistently smaller climate impact than methane. As with other short-lived species, the radiative forcing from a continuous emission of hydrogen is proportional to emission rates, whereas the radiative forcing from a continuous emission of carbon dioxide is closely related to cumulative emissions. After a cessation of hydrogen emissions, the Earth cools rapidly, whereas after a cessation of carbon dioxide emissions, the Earth continues to warm somewhat and remains warm for many centuries. Regardless, our results support the conclusion of Ocko and Hamburg (2022) that, if methane were a feedstock for hydrogen production, any possible near-term consequences will depend primarily on methane leakage and secondarily on hydrogen leakage.

Steam reforming of ethanol, acetaldehyde, acetone and acetic acid: Understanding the reaction intermediates and nature of coke

The small aliphatic organics like ethanol, acetaldehyde, acetone and acetic acid are frequently used as feedstocks for hydrogen production via steam reforming. These organics have distinct functionalities, which might result in formation of different reaction intermediates and coke. This was investigated in this study with Ni/KIT-6 as a catalyst under normalized conditions. The results indicated that dehydration to ketene but not cracking was major route for dissociative adsorption of acetic acid on Ni/KIT-6 from 100 °C. Thermally stable CH and CC in alkenes, formed via dehydration of ethanol and aromatization of acetone/intermediates via bimolecular Aldol-condensation, were important precursors of coke in ethanol and acetone reforming. Although acetone strongly adsorbed on Ni/KIT-6, it did not polymerize to heavy oxygen-containing organics that were difficult to be gasified with steam. In comparison, the similar strong adsorption of acetaldehyde led to rapid polymerization even at 100 °C, forming the polymeric coke of highly aliphatic nature. The coking tendency in reforming followed the order: acetone > acetic acid > ethanol > acetaldehyde. Nevertheless, the amorphous form of coke in acetaldehyde reforming led to the rapid deactivation of Ni/KIT-6. The coke in ethanol, acetone and acetic acid reforming were mainly the catalytic type with the highly aromatic nature, high carbon crystal crystallinity, high thermal stability, high resistivity towards oxidation and the carbon nanotube morphology. Nevertheless, the varied reaction intermediates involved in reforming of these varied feedstock also formed the coke of some unique features.

Steam reforming of alcohols and carboxylic acids: Importance of carboxyl and alcoholic hydroxyl groups on coke properties

Alcohols and carboxylic acids have been used intensively as feedstock for production of hydrogen via steam reforming. They have different functionalities and might exhibit the distinct coking behaviors. In this study, ethanol, n-propanol, acetic acid and propionic acid were chosen as the representatives of alcohols/carboxylic acids and their reaction characteristics in steam reforming over Ni/SBA-15 catalyst were comparatively investigated with the focus on understanding the difference of the properties of the coke formed. The results indicated that although the steam reforming of the alcohols generated more coke than that of the carboxylic acids, the catalyst showed the higher catalytic stabilities, due to different properties of the coke formed. The steam reforming of the alcohols produced the coke of higher aromaticity with a higher content of carbon, more large defective aromatic rings, higher crystallinity, higher thermal stability and resistivity towards the oxidation than that from steam reforming of the carboxylic acids. The coke in the carbon nanotube form in steam reforming of the alcohols and the carboxylic acids also differed in terms of wall thickness and length of the carbon nanotubes, as the reaction intermediates were different. The encapsulating coke was more abundant in steam reforming of carboxylic acids, as carboxylic acids are prone to form the amorphous thermal coke via cracking, which led to rapid deactivation of the catalyst. The types or properties of the coke, not only the amount, play important roles in determining stability of the catalyst.

Green hydrogen from microalgal liquefaction byproducts with ammonia recovery and effluent recycle for developing circular processes

Hydrothermal liquefaction is a promising technology for microalgae-based biofuel production. However, hydrothermal liquefaction’s aqueous wastes have little established reuse, and contain significant fractions of toxic ammoniacal nitrogen. Careful reuse of this waste can assure microalgae-based biofuels are produced with less environmental impact and larger energy efficiency. Microbial electrolysis cells were investigated to valorize this waste product by converting the leftover organics into hydrogen and remove ammonia. Waste hydrothermal liquefaction aqueous phase from two microalgal strains, Tetraselmis sp. and Chlorella sp. were used as feedstocks for hydrogen production in microbial electrolysis cells. Chlorella and Tetraselmis aqueous phase-fed microbial electrolysis cells reach an average current density of 5.1 ± 0.19 A/m2 and 3.8 ± 0.08 A/m2. Compound removal rates and mass removal percentages were also investigated for each feedstock. Acetic acid, propionic acid, ethanol, and glycerol were effectively removed from the aqueous byproduct. Further, microbial electrolysis cells separated up to 34.3% of ammoniacal nitrogen present in the aqueous phase. Charge transfer analysis indicated that proton transfer, not ammonium transfer, contributed to the majority of the hydrogen production in the cathode. Finally, the microbial electrolysis cell effluent was reused to grow the same microalgal strains, leading to the development of a circular biofuel production system. Microalgae regrowth studies using microbial electrolysis cell effluent showed nearly complete removal of total organic carbon, but significantly less removal of total nitrogen. Tetraselmis sp. growth occurred with the Tetraselmis-derived MEC effluent, however, the control medium without effluent produced the most growth. These findings support the possibility of a circular biofuel framework using MECs, but additional constraints, including the removal of inorganic contaminants, are necessary to realize the circular processes.

Upgrading biogas with novel composite carbon molecular sieve (CCMS) membranes: Experimental and techno-economic assessment

The use of biogas as feedstock for hydrogen production was widely proposed in the literature in the last years as a strategy to reduce anthropogenic carbon emissions. However, its lower heating value compared to natural gas hampers the revamping of existing reforming plants. The use of composite carbon molecular sieve membranes for biogas upgrading (CO2 removal from biogas) was investigated experimentally in this work. In particular, ideal perm-selectivities and permeabilities above the Robeson plot for CO2/CH4 mixtures have been obtained. These membranes show better performances compared to polymeric membranes, which are nowadays commercialized for CO2 separation in natural gas streams. Compared to polymeric membranes, carbon membranes do not show deactivation by plasticization when exposed to CO2, and thus can find industrial application. This work was extended with a techno-economic analysis where carbon membranes are installed in a steam methane reforming plant. Results have been first validated with data from literature and show that the use of biogas increases the costs of hydrogen production to a value of 0.25 €/Nm3 compared to the benchmark technology (0.21 €/Nm3). On the other hand, the use of biogas leads to a decrease in carbon emissions up to 95%, thus the use of biogas for hydrogen production is foreseen as a very interesting alternative to conventional technologies in view of the reduction in the carbon footprint in the novel technologies that are to be installed in the near future.

Continuous hydrogen production by dark and photo co-fermentation using a tubular multi-cycle bio-reactor with Paulownia biomass

Bio-hydrogen production from lignocellulosic biomass has shown significant potential for helping to meet future energy demand. In the present work, we have utilized the Paulownia lignocellulosic biomass as feedstock for hydrogen production which has great potential for sustainable supply over the year due to its high growth rate. A dark and photo co-fermentative mechanism was adopted in a newly proposed tubular multi-cycle bioreactor and a 30-day continuous hydrogen production trial was conducted in the reactor. The key factors such as hydraulic retention time and organic loading rate associated with hydrogen production and substrate degradation were regulated to optimize the bioprocess. Our experimental findings show that with increase in hydraulic retention time and organic loading rate, hydrogen yield decreases and increases respectively. We have observed hydrogen yield, hydrogen concentration and substrate conversion ratio of 0.54 L/h, 53.84%, and 89.93% at optimized parameters of hydraulic retention time of 40 h, OLR of 1.0 g/L h, and light–dark interval time of 1:4 respectively. Our experimental finds may help to further explore the hydrogen production potential from lignocellulosic biomass of Paulownia.

Hydrogenation of plasma-excited nitrogen over an alumina catalyst for ammonia synthesis

Ammonia (NH3) is a potential hydrogen carrier as alternative fuel and feedstock for hydrogen production. In this study, plasma synthesis of NH3 was conducted in a packed-bed dielectric barrier discharge (DBD) reactor using Al2O3 as the catalyst. In order to explore the mechanism of hydrogenation of plasma-excited nitrogen for NH3 synthesis, the whole NH3 synthesis process was divided into three steps including N2 activation, hydrogenation of plasma-excited N(a), and desorption of NH3(a) from catalyst. The effects of reaction conditions on the three steps and corresponding NH3 production were examined. Results showed that more plasma-excited nitrogen species were formed through N2 activation at higher N2 flow rate, discharge time and discharge power for N2 activation. Hydrogenation of plasma-excited N(a) to form NH3(a) was improved by more discharge time at the second step. Higher discharge temperature for N(a) hydrogenation favored NH3(a) desorption from catalyst and increased NH3 production at the second step, with the total NH3 yield slightly changed. In addition, one-step NH3 synthesis in plasma was investigated and compared with the three-step process. The results will provide reference for catalyst and reactor design in plasma synthesis of ammonia.

Investigating the applicability of Athabasca bitumen as a feedstock for hydrogen production through catalytic supercritical water gasification

Supercritical water gasification has been a promising technique for hydrogen production using several lignocellulosic biomasses and organic wastes. Various organic wastes such as sewage sludge, lignocellulosic biomass, municipal solid waste, industrial effluents and cattle manure that have been used as feedstocks for supercritical water gasification. With the objective of hydrogen production from alternative and less explored resources, Canadian Athabasca bitumen was used as a feedstock for supercritical water gasification in this study. Bitumen was gasified in supercritical water to examine the impacts of temperature (550–700°C), feedstock concentration (20–35wt%) and reaction time (15–60min) at the reactor pressure of 23MPa. The improvements in hydrogen yields with the use of four different heterogeneous catalysts such as FeCl3, ZnCl2, Ni/Si-Al2O3 and Ru/Al2O3 at 5wt% loading were targeted. Prior to gasification in a tubular batch reactor, bitumen was characterized for determining its ultimate composition (carbon-hydrogen-nitrogen-sulfur-oxygen, CHNSO analysis), surface organic functional groups (Fourier-transform infrared spectroscopy, FTIR) and devolatilization behavior (thermogravimetric analysis, TGA). In non-catalytic gasification, the highest hydrogen yields (2.26mmol/g) and total gas yields (4.68mmol/g) were obtained at 700°C in 60min of reaction time with 20wt% feed concentration. 5wt% ZnCl2 enhanced the gasification rate with hydrogen yields up to 3.57mmol/g. The overall catalyst activity towards maximizing hydrogen yields was in the order of ZnCl2>FeCl3>Ru/Al2O3>Ni/Si-Al2O3. This study is an initial attempt to determine the candidacy of bitumen as a possible resource for hydrogen generation.

Economic analysis and optimization for bio-hydrogen production from oil palm waste via steam gasification

ABSTRACTBiomass steam gasification with in situ carbon dioxide capture using CaO exhibits good prospects for the production of hydrogen-rich gas. In Malaysia, due to abundance of palm waste, it is a good candidate to be used as a feedstock for hydrogen production. The present work focuses on the mathematical modeling of detailed economic analysis and cost minimization of the flow sheet design for hydrogen production from palm waste using MATLAB. The influence of the operating parameters on the economics is studied. It is predicted that hydrogen cost decreases by increasing both temperature and steam/biomass ratio. Meanwhile, the hydrogen cost increases when increasing sorbent/biomass ratio. Cost minimization solves to give optimum cost of 1.9105 USD/kg with hydrogen purity, hydrogen yield, hydrogen efficiency, and thermodynamic efficiency are 79.9 mol%, 17.97 g/h, 81.47%, and 79.85%, respectively. The results indicate that this system has the potential to offer low production cost for hydrogen production from palm waste.

Mathematical Modelling for Hydrogen Production from Steam Gasification of Cellulose

In Malaysia, due to its abundance, oil palm is a good candidate to be used as a feedstock for hydrogen production. Oil palm biomass generally consists of cellulose, hemicellulose and lignin. Steam gasification, coupled with CO2 removal has been shown to be one of the promising methods for hydrogen production. This work focuses on the mathematical modeling of hydrogen production from cellulose via steam gasification and steam gasification with in-situ CO2 capture using CaO. The results are compared and rationalized against published data on steam gasification of pure cellulose and good agreement is observed. The model predicts an increase in hydrogen output from 48 to 56 mol% with the addition of CaO into the system. By increasing temperature and steam/biomass ratio the cold gas efficiency decreases, however, temperature have higher impact compared to steam/biomass ratio.

Evaluation of hydrogen production from corn cob with the mesophilic bacterium Clostridium hydrogeniproducens HR-1

Corn cob is a promising hydrogen fermentation substrate, not only because of its abundant and low cost, but also because of its high cellulose and hemicellulose content. However, little information is available on the use of corn cob as a feedstock for hydrogen production. In this study, corn cob was hydrolyzed by cellulase after acid steam-explosion, alkali soaking, or steam-explosion pretreatment. The liquid products of pretreatment and the enzymatic hydrolysates were then used as carbon sources for hydrogen production by Clostridium hydrogeniproducens HR-1. Pretreatment followed by enzymatic hydrolysis yielded 720, 670, and 530 mg reducing sugars/g corn cob, and the hydrogen yield from corn cob reached 119, 100, and 83 ml H2/g corn cob, which is 55.9%, 46.7%, and 38.8% of the theoretical hydrogen yield from corn cob using C. hydrogeniproducens HR-1, respectively.

Using a food and paper-cardboard waste blend as a novel feedstock for hydrogen production: Influence of key process parameters on microbial diversity

In this study, fermentation of a thermally treated simulated organic solid waste into hydrogen (H2) was examined using a pretreated anaerobic mixed culture. The culture was fed a steam exploded food waste plus paper-cardboard waste blend liquor with and without linoleic acid (LA). The individual and interaction effects of the initial pH, LA concentration and the initial chemical oxygen demand (COD) concentration on H2 and methane (CH4) production was assessed using a Box–Behnken design (BBD). The BBD model predicted a maximum H2 yield of 87 mL g−1 COD or 98 mL H2 g−1 VS with 1.6 g L−1 LA, an initial pH of 5.93 and an initial COD of 9.34 g COD L−1. The major microbial populations detected in cultures at pH 5.5 with and without LA included Clostridium sp., Enterococcus asini, Enterococcus faecalis, and Lactobacillus gallinarum. The dendrogram for the 16S rRNA gene T-RFs profiles showed four major groups with a similarity index of 72–75% for Clade III. The major H2-producing populations were grouped in Clade I with a similarity index range of 55–75%.

Characterization of cellulolytic enzymes and bioH 2 production from anaerobic thermophilic Clostridium sp. TCW1

A thermophilic anaerobic bacterium Clostridium sp. TCW1 was isolated from dairy cow dung and was used to produce hydrogen from cellulosic feedstock. Extracellular cellulolytic enzymes produced from TCW1 strain were identified as endoglucanases (45, 53 and 70 kDa), exoglucanase (70 kDa), xylanases (53 and 60 kDa), and β-glucosidase (45 kDa). The endoglucanase and xylanase were more abundant. The optimal conditions for H 2 production and enzyme production of the TCW1 strain were the same (60 °C, initial pH 7, agitation rate of 200 rpm). Ten cellulosic feedstock, including pure or natural cellulosic materials, were used as feedstock for hydrogen production by Clostridium strain TCW1 under optimal culture conditions. Using filter paper at 5.0 g/L resulted in the most effective hydrogen production performance, achieving a H 2 production rate and yield of 57.7 ml/h/L and 2.03 mol H 2/mol hexose, respectively. Production of cellulolytic enzyme activities was positively correlated with the efficiency of dark-H 2 fermentation.