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To develop earth-abundant and cost-effective catalysts for overall water splitting is still a major challenge. Herein, a unique “raisins-on-bread” Ni–S–P electrocatalyst with NiS and Ni2P nanoparticles embedded in amorphous Ni(OH)2 nanosheets is fabricated on Ni foam by a facile and controllable electrodeposition approach. It only requires an overpotential of 120 mV for HER and 219 mV for OER to reach the current density of 10 mA cm−2 in 1 M KOH solution. Employed as the anode and cathode, it demonstrates extraordinary electrocatalytic overall water splitting activity (cell voltage of only 1.58 V @ 10 mA cm−2) and ultra-stability (160 h @ 10 mA cm−2 or 120 h @50 mA cm−2) in alkaline media. The synergetic electronic interactions, enhanced mass and charge transfers at the heterointerfaces facilitate HER and OER processes. Combined with a silicon PV cell, this Ni–S–P bifunctional catalyst also exhibits highly efficient solar-driven water splitting with a solar-to-hydrogen conversion efficiency of 12.5%.

The experiments on microwave pyrolysis of soybean straw are studied to produce hydrogen-rich gas under CO2 atmosphere in this paper. The microwave power has an important effect on the temperature. ...

Bio-oil model compounds dry (CO2) reforming for hydrogen production over Ni/Al2O3 catalyst is presented in this paper. The research investigates the effects of reaction conditions such as temperature, weight hourly space velocity of the aqueous phase (WHSV), CO2 to carbon in bio-oil ratio (CO2/Bio-oil) on hydrogen yield and products distribution. And also study the coke formation rates versus different reaction temperature and different CO2/Bio-oil ratio. Meanwhile analyze the types of carbon deposited on Ni/Al2O3 catalyst. The experimental results show that, the optimum reaction temperature is 700 °C, CO2/Bio-oil is 0.75, WHSV is 0.9 h−1, under these conditions, hydrogen yield and bio-oil model compounds conversion reach 88.19% and 96.87% respectively, the molar ratio of H2/CO reaches 1.08. The coke formation rate exists a maximum at 600 °C, higher temperature (>600 °C) and higher CO2/Bio-oil (>0.75) are all good for carbon elimination of dry reforming. The forms of carbon deposit on Ni/Al2O3 catalyst are mainly filamentous carbon and graphitic carbon.

In the present work, hydrolysis of sweet sorghum bagasse residue using dilute acid was investigated. The sweet sorghum bagasse residue was from pretreatment. Process parameters investigated include reactor temperature, reaction time, and acid concentration in order to find suitable conditions for hydrolysis of the cellulose fraction. The effects of dilute acid hydrolysis were assessed by glucose yield and decomposition products concentration. The highest yield of glucose, 70.10%, was found at the temperature of 170°C, acid concentration of 1.0% (w/w), and a reaction time of 10 min. Meanwhile, 0.99 g/L of acetic acid, 0.22 g/L of furfural, 0.73 g/L of hydro-xymethyl furfural, and 1.60 g/L of levulinic acid were obtained under these conditions, which concluded that the decomposition of glucose was slight and confirmed the selectivity of this dilute acid hydrolysis of the sweet sorghum bagasse residue. The present work aims to take full advantage of the sweet sorghum bagasse residue and obtain glucose soluti...

Hydrolysis of hemicellulose and disruption of cellulose during pretreatment process are conducive to the following cellulase hydrolysis performance. In this work, bagasse pith was first pretreated by 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) solution containing 0–1.2% hydrochloric acid (HCl) and 30% water. The water (30%) added into the acidic ionic liquid (IL) solutions led to an increase in the biomass loading up to a biomass/IL solutions ratio of 1:10 (wt.%). Hemicellulose was hydrolyzed to reducing sugars by HCl and cellulose was dissolved by [BMIM]Cl. In this process, 76.9% of hemicellulose conversion and 95% of cellulose recovery were obtained. The pretreated bagasse pith was then followed by hydrolysis with commercially available enzymes. The effects of pretreatment temperature, reaction time and acid concentration on cellulase hydrolysis of pretreated bagasse pith were investigated. Pretreatment of bagasse pith with [BMIM]Cl solutions containing 1.0% HCl at 120 °C for 30 min resulted in the glucose concentration of 92.3 g/l and yield of 94.5% after 72 h of cellulase hydrolysis. The maximum total reducing sugars yield reached to 89.9% after pretreatment and cellulase hydrolysis.

A mixture of several typical model compounds was chosen as the bio-oil model. Hydrogen production via catalytic steam reforming of model bio-oil in a two-stage reaction system was studied in this article. Quartz sand was used in the first-stage fluidized bed reactor for primary steam reforming, and Ni/modified dolomite was chosen as the catalyst in the second-stage fixed bed reactor for deep steam reforming. The main influential parameters, such as temperature, steam to carbon ratio, and weight hourly space velocity, were tested in this work. The optimum conditions on hydrogen production were obtained at 800°C; steam and carbon mole ratio, 12; and weight hourly space velocity, 1 h−1. In addition, there was a comparison between a two-stage reaction system and one-stage fixed bed reactor on the optimum condition. It was concluded that H2 yield decreased 5.6% in the two-stage reaction system and 9.9% in the one-stage fixed bed reactor after 3 h reaction time; the maximum carbon deposition ratio was 1 and 0.4...

In the present work, pretreatment of sweet sorghum stalk using dilute acid was investigated under mild conditions. Process parameters investigated include reactor temperature, reaction time, and acid concentration. Xylose concentration, xylose yield, and decomposition product concentrations are measured. The highest yield of xylose (77.5%) is achieved under optimum conditions. The optimal conditions selected are 0.75% (w/w) acid concentration, 140°C, and 10 min. Using theses conditions, 23.9 g/L of xylose concentration, 0.98 g/L of furfural, and 2.52 g/L of acetic acid are obtained. The decomposition product concentrations are low.

H2 production by steam reforming of fast pyrolyzed bio-oil over Ni/MgO-La2O3-Al2O3 catalyst was carried out in a fixed-bed reactor by using model compounds (acetic acid, furfural, cyclopentanone, and m-cresol) and real bio-oil as the starting materials. The carbon deposition mechanism was discussed and a model of carbon deposition was built based on the amount of coke formed under different reaction temperatures, reaction times, steam to carbon molar ratios (S/C), and liquid hourly space velocities. The activation energies in the carbon deposition reaction and in the carbon elimination reaction were calculated as 28 and 71 kJ/mol, respectively, in terms of the carbon deposition model employed.

Ni-Co/γ-Al2O3, Ni/γ-Al2O3, Co/γ-Al2O3, mechanical mixed Ni/γ-Al2O3, and Co/γ-Al2O3 catalyst (another name is Ni/γ-Al2O3|Co/γ-Al2O3) were prepared by the wet impregnation method, and the catalytic performance for hydrogen production by catalytic reforming of volatile from biomass pyrolysis over the four catalysts was compared under the condition of different temperatures and weight hourly space velocity. The experimental results show that the catalytic performance of the four catalysts from high to low is Ni-Co/γ-Al2O3 > Co/γ-Al2O3 > Ni/γ-Al2O3|Co/γ-Al2O3 > Ni/γ-Al2O3 within the studied temperature and weight hourly space velocity scope. Hydrogen selectivity of 94.83% and hydrogen yield of 120.81 g/kg biomass (dry basis) were obtained over Ni-Co/γ-Al2O3 under the condition of catalytic reforming temperature of 825°C and weight hourly space velocity of 0.71 h−1.

In this article, the integrated process technology is introduced for production of hydrogen, which incorporates pyrolysis of biomass and catalytic steam reforming. The process adopts a fluidized bed reactor for pyrolysis and a fixed bed reactor for steam reforming, in which technological parameters, such as pyrolysis temperature, ratio of steam over biomass, reforming temperature, gas hourly space velocity, catalyst size, and the life of the catalyst, were investigated in order to conclude their effects on the hydrogen production. Results from experiments indicate the concentration of hydrogen in the gaseous product and thus the hydrogen yield increases as both operation temperatures of pyrolysis and reforming increase while catalyst size reduces. The increase in steam over biomass, however, results in hydrogen yield varying from increase to decrease.

Many oxygen compounds were contained in bio-oil, such as acids, alcohols, ketones, aldehydes, phenols, and sugar. Acetic acid, ethylene glycol, butanone, furfural, and m-cresol were selected as bio-oil model compounds in this article. Hydrogen production was carried out via catalytic steam reforming under the conditions of the mole ratio of steam and carbon = 6, liquid hourly space velocity = 5 h−1, and 600°C with catalyst Ni/MgO. Infrared gas analyzer was used to analyze gas concentration via catalytic steam reforming of model compounds on line, while the liquid products from a collection device were analyzed by gas chromatography/mass spectrum. Intermediates were formed under catalytic steam reforming through elimination and recombination reaction, etc. The intermediates reacted with steam to produce H2 and CO2, and then the reactions reached equilibrium in the end. The hydrogen yield of acetic acid, ethylene glycol, and butanone as materials were higher than that of furfural and m-cresol as materials a...

Pyrolysis kinetic characteristics of sawdust samples were studied at heating rates of 30, 40, and 50°C·min−1 by thermogravimetric analysis. The pyrolysis of sawdust could be divided into five stages, and Sestak's complex mechanism was used to study the mechanism of each stage. The thermal degradation mechanism, activation energy, and frequency factor of each stage were obtained by multi-linear regression using Microsoft Excel. The results showed that the Sestak-Berggren function is very suitable for the mechanism analysis of complex systems.

Biomass fast pyrolysis oil (bio-oil) is considered a promising renewable liquid energy. A feasible upgrading method is co-processing HHDO-oil, which is the heavy fraction of hydrodeoxygenated pyrolysis oil (HDO-oil), with paraffin oil. In this article, kinetic modeling for catalyst deactivation by coke was researched. The results show that the coke is lower by co-processing of HHDO with paraffin oil than other upgrading. Catalyst deactivation is a cascade reaction, the effect of HHDO concentration from 3.18 to 5.08 mol/m3 and the effect of temperature from 753 to 793 K were studied. The kinetic model equation of catalyst deactivation is −da/dt = 1.188 × 10−5 e 18914.85/RT · c 0.88 · a.

Biomass gasification to produce syngas was carried out in a fluidized bed reactor and a catalytic fixed bed reactor. The feedstock was sawdust and the cracking catalyst included the calcined dolomite, Ni/dolomite, Ni/modified dolomite, and reforming catalyst. The Ni/modified dolomite catalyst showed better performance and low cost. The optimum technological conditions were as follows: fluidized bed temperature, 1,073 K; catalytic fixed bed temperature, 1,073 K; the mass ratio of steam to biomass, 2.0.

Biomass fast pyrolysis oil (bio-oil) is considered to be a promising renewable liquid energy carrier. But it cannot be applied in stationary combustion engines, so upgrading is required. A considerable alternative upgrading method is hydrodeoxygenation; the heavy fraction of hydrodeoxygenated pyrolysis oil (HDO-oil) is called HHDO-oil. In this article, HHDO-oil co-processed with paraffin oil in a fixed-bed was studied under the conditions of different temperatures, different weight hourly space velocity, and also different co-processed ratio. It was found that co-processing of 20 wt% HHDO-oil with paraffin oil gave higher yields of liquid and better oil quality than that of the pure paraffin oil cracking. The optimum operating condition was at 520°C, the weight hourly space velocity was 4.0 h−1, and the co-processed ratio was 20%. In this operating condition, it produced the highest yield of liquid, which was 78.65 wt%, including gasoline fraction that was 8.48 wt%, diesel fraction was 37.37 wt%, lubrican...

Steam reforming of biomass derived bio-oil liquid products was an available low carbon technology to produce sustainable hydrogen fuel. In this article, a series of nickel-based catalysts have been prepared. To examine the catalytic steam reforming behaviors over these catalysts in a fixed bed reactor system, several typical oxygen-containing chemicals, including acetic acids, furfural, cyclopentanone, and meta-cresol, that were proved to be contained in the bio-oil feedstock, were first selected as model starting materials. In these tests, yields for hydrogen were taken as an index of the catalyst activity and the catalyst that exhibited the maximum activity by hydrogen yields was then used for the bio-oil steam reforming studies. In this work, it was concluded that the catalyst activity reached a maximum hydrogen yield of 90.56% and decreased in an order of Ni/MgO-La2O3-Al2O3 > Ni/MgO-Al2O3 ≈ Ni/La2O3-Al2O3 > Ni/Al2O3. The yield of hydrogen for steam reforming of the whole fraction of the bio-o...

Four bifunctional catalysts were prepared by physical mixing of a commercial methanol synthesis catalyst (JC207 catalyst, a catalyst for methanol synthesis, which has been industrialized in China) with zeolite HZSM-5 (Si-Al ratios of 25, 38, 50, 150) as a methanol dehydration catalyst. The bifunctional catalyst (JC207/HZSM-5 [Si/Al = 38]) showed better performance, which can be attributed to more acidic sites with moderate strength of zeolite, and which can control methanol dehydration rate, which is a rate determining step.

HZSM-5 zeolites modified by MgO, CaO, and ZnO were prepared by impregnation and bifunctional catalysts were prepared by modified HZSM-5 zeolites and JC207 catalyst (a catalyst for methanol synthesis, which has been industrialized in China). Evaluation of catalytic activity was conducted in a fixed-bed reactor. Results show, with proper basic oxide-modified zeolite, a Br⊘nsted acid site (strong acid sites) shift to Lewis acid site (weak acid sites). Weak and less strong acid sites on HZSM-5 zeolite are activity centers for the formation of dimethyl ether (DME), whereas strong acid sites for by products such as hydrocarbons. Consequently, the selectivity of CO2 and hydrocarbons decrease, especially with zeolite modified by CaO.

Bio-oil reforming to produce hydrogen could be an attractive option for sustainable hydrogen. Hydrogen production via catalytic steam reforming of bio-oil in a fluidized-bed reactor was studied in this paper. The optimum conditions on hydrogen production were obtained at 700 °C, steam/carbon mole ratio (S/C) of 17, and weight hourly space velocity (WHSV) of 0.4 h−1. In addition, the reason for catalyst deactivation in a fluidized-bed reactor was investigated. The fresh and deactivation catalysts were analyzed by X-ray diffraction (XRD), Brunauer−Emmett−Teller (BET), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), which showed that the carbon deposition is not the main reason for catalyst deactivation. The main reason for fresh catalyst deactivation was the NiO grain sintered on the supporter surface.

In the technology of manufacturing fuel alcohol from biomass as feedstock, hydrolysis using dilute acid as catalyst is one way to produce fermentable saccharide. In this process, the yield of xylose is always low because of the degrading during the acid environment. In this paper, the degrading kinetics of xylose in the hydrolysate was investigated under the conventional process conditions of the hydrogen ion range from 0.05 to 0.2 mol L−1 and the temperature range from 150 to 200°C. Through the numerical calculation method, the kinetic parameters were estimated and the activation energy of xylose in the degrading reaction was obtained. The kinetic equations that correlated the effect of hydrogen ion concentration on the rate constants of the degrading reaction were established. Comparisons between calculated results and the experimental results have proved that the established kinetic model can satisfactorily predict the degradation behaviours of xylose in the acidic hydrolysate.

The apparent activation energy of transesterification of soybean oil with methanol was investigated by the use of magnesium methoxide as solid base catalyst. The effect of variations in reaction time and temperature (50-65°C) on the macro reaction rate were studied while the molar ratio of methanol to oil (9 : 1) and the mass ration of catalyst to oil (8 wt%) were held. The experimental data were curve-fitted by using Origin software, and the relationship of FAME concentration with the reaction time was given, and the apparent activation energy was calculated. The total apparent activation energy was 46.3878 kJ mol−1 and k0 was 5.9112 × 105 L mol−1 min−1. And the apparent activation energies of each fatty acid composition were 36.16, 39.54, 54.23, 43.50 and 32.15 kJ mol−1 for the palmitic acid, stearic acid, oleic acid, linoleic acid and linolenic acid, respectively.