共查询到20条相似文献,搜索用时 31 毫秒
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Mi-Sun Kim Jin-Sook Baek Young-Su Yun Sang Jun Sim Sunghun Park Sun-Chang Kim 《International Journal of Hydrogen Energy》2006
Chlamydomonas reinhardtii UTEX 90 accumulated 1.45 g dry cell weight and 0.77 g starch/L during photosynthetic growth using TAP media at 25 °C in presence of 2% CO2 for 3 days. C. reinhardtii biomass was concentrated and then converted into hydrogen and organic acids by anaerobic fermentation with Clostridium butyricum. Organic acids in the fermentate of algal biomass were consecutively photo-dissimilated to hydrogen by Rhodobacter sphaeroides KD131. In the concentrated algal biomass 52% of the starch was hydrolyzed to 37.1 mmol H2/L-concentrated algal biomass and 13.6, 25.5, 7.4 and 493 mM of formate, acetate, propionate, and butyrate, respectively by C. butyricum. R. sphaeroides KD131 evolved 5.72 mmol H2 per ml-fermentate of algal biomass under illumination of 8 klux at 30 °C. Only 80% of the organic acids, mainly butyrate, were hydrolyzed during photo-incubation. During anaerobic conversion, 2.58 mol H2/mol starch–glucose was evolved using C. butyricum and then 5.72 mol H2/L-anaerobic fermentate was produced by R. sphaeroides KD131. Thus, the two-step conversion process produced 8.30 mol H2 from 1 mol starch–glucose equivalent algal biomass via organic acids. 相似文献
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Tatyana V. Laurinavichene Alexander S. Fedorov Maria L. Ghirardi Michael Seibert Anatoly A. Tsygankov 《International Journal of Hydrogen Energy》2006
It was demonstrated that immobilized, sulfur-deprived algal cultures can photoproduce H2. After identifying the optimal material and procedures for immobilization of Chlamyodomonas reinhardtii at high cell density, we examined the effect of liquid mixing, sulfate content, acetate levels and light intensity on the H2-production activity of the culture. Our results indicate that (a) liquid mixing is important to provide homogeneous conditions for the immobilized culture; (b) sulfur deprivation is necessary for hydrogen production by immobilized cultures; and (c) high light intensity decreases H2 production. The maximum total volume of H2 produced by the system (160 ml of reactor volume) was 380 ml over 23 days, and the highest rate of H2 production observed was 45 ml day-1. Cell immobilization significantly increased the duration of the H2-photoproduction phase (up to 4 weeks), maintained specific rates of H2 photoproduction similar to those of suspension cultures and showed potential for large increases in H2 production. 相似文献
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Particular active sites, xM–yM′ (where x and y are the number of unsaturations, i.e. anionic vacancies, on each cation M and M′) involving reactive hydrogen are created during the activation of non-metallic catalytic materials. The anionic vacancies created in bulk and at the surface of the solid, by the loss of H2O or H2S, are able to receive hydrogen in a hydridic form according to a heterolytic dissociation (X2-Mn+□+H2→XH-Mn+H- with X=O or S). The non-metallic catalytic materials become catalytic hydrogen reservoirs. Besides a high reactivity, the hydrogen species, stored in the solid, present marked diffusion properties leading to a dynamic behavior of the solid and active sites. 相似文献
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Jong Hyun Yoon Ji Hae Shin Mi-Sun Kim Sang Jun Sim Tai Hyun Park 《International Journal of Hydrogen Energy》2006
Cyanobacteria provide an efficient system for producing H2 from water using solar energy. The energy conversion efficiency can be defined by the ratio of H2 produced to the light energy absorbed. An IR and opalescent plate method was used to measure the light energy absorbed. Since cyanobacteria absorb light in the visible range but not in the infrared range, the net amount of light energy absorbed by the cells can be estimated by measuring the IR and visible light intensities transmitted through the biochamber. A rectangular biochamber was used for measuring the conversion efficiency from light energy to H2 energy. A quantum meter and radiometer were used to measure the light intensity transmitted through the chamber. Anabaena variabilis was cultured in a BG11 medium with 3.6 mM NaNO3 and the light intensity was 40–50 μmol/m2/s in the growth phase and 120–140 μmol/m2/s in the H2 production phase. The maximum H2 production was 50 ml for 40 h and cell density was 1.2 g/l. The H2 production rate was 4.1 ml H2/g dry cell weight/h. Based on the light absorbed in the H2 production phase, the energy conversion efficiency from light to H2 was 1.5% on average and 3.9% at the maximum. Based on the light energy absorbed in the cell growth and H2 production phases, the energy conversion efficiency was 1.1% on average. 相似文献
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In this study, biohydrogen production from glucose by two fermentative bacteria (Clostridium butyricum, a typical strictly anaerobic bacterium, and Klebsiella pneumoniae, a well-studied facultative anaerobic and nitrogen-fixing bacterium) are stiochiometrically analyzed according to energy (ATP), reducing equivalent and mass balances. The theoretical analysis reveals that the maximum yield of hydrogen on glucose by Clostridium butyricum is 3.26 mol/mol when all acetyl-CoA entering into the acetate pathway (α=1), which is higher than that by Klebsiella pneumoniae under strictly anaerobic conditions. In the latter case, the maximum yield by Klebsiella pneumoniae is 2.86 mol hydrogen per mol glucose when five sevenths of acetyl-CoA is transformed to acetate. However, under microaerobic condition the maximum yield of hydrogen on glucose by Klebsiella pneumoniae could reach 6.68 mol/mol if all acetyl-CoA entered into tricarboxylic acid (TCA) cycle (γ=1) and a quantity of 53% of the reducing equivalents generated in the metabolism were completely oxidized by molecular oxygen. On the other hand, the relationship between hydrogen production and biomass formation is distinct by Clostridium butyricum from that by Klebsiella pneumoniae. The former yield of hydrogen on glucose increases as biomass. In contrast, the latter one decreases as biomass in a certain range of molar fraction of acetate in total acetyl-CoA metabolism (5/7?β?0). Microaerobic condition is favorable for high hydrogen production with low biomass formation by Klebsiella pneumoniae in a certain range of the molar fraction of all reducing equivalents oxidized completely by molecular oxygen (0.53?δ?0.83). 相似文献
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Vibha R. Satsangi Saroj Kumari Aadesh P. Singh Rohit Shrivastav Sahab Dass 《International Journal of Hydrogen Energy》2008
With the advent of nanotechnology there has been a resurge of interest in α-Fe2O3, as suitable candidate for photoelectrochemical (PEC) splitting of water to generate hydrogen. This paper describes the enhanced PEC behaviour of nanostructured α-Fe2O3 thin films modified by various techniques. Nanostructured thin film/pellets of α-Fe2O3 prepared by various techniques and various dopants were investigated for their photoelectrochemical response. Thin films prepared by spray pyrolysis having particle size of 20–30 nm exhibited better photoresponse as compared to the films prepared by sol–gel methods, which further improved on doping with Zn. These films were further modified by (i) depositing Zn dots on the surface of α-Fe2O3 films using thermal evaporation method and (ii) irradiating it with 170 MeV Au13+ ions. When used as electrode in photoelectrochemical cell, a significant increase in the photoresponse of these modified films were observed, details of which are discussed. 相似文献
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This paper compares the performance of three different solar based technologies for a stand-alone power supply (SAPS) using different methods to address the seasonal variability of solar insolation—(i) photovoltaic (PV) panels with battery storage; (ii) PV panels with electrolyser and hydrogen (H2) storage; and (iii) photoelectrolytic (PE) dissociation of water for H2 generation and storage. The system size is determined at three different Australian locations with greatly varying latitudes—Darwin (12°S), Melbourne (38°S) and Macquarie Island (55°S). While the PV/electrolyser system requires fewer PV panels compared to the PV/battery scenario due to the seasonal storage ability of H2, the final number of PV modules is only marginally less at the highest latitude due to the lower energy recovery efficiency of H2 compared to batteries. For the PE technology, an upper limit on the cost of such a system is obtained if it is to be competitive with the existing PV/battery technology. 相似文献
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This paper presents experimental study on catalytic autothermal reforming (ATR) of natural gas (NG) for hydrogen (H2) production over sulfide nickel catalyst supported on gamma alumina. The experiments are conducted on a cylindrical reactor of 30 mm in diameter and 200 mm in length with “simulated” NG of different composition under thermal-neutral conditions and fed with different molar air to fuel ratio (A/F) and molar water to fuel ratio (W/F). The results showed that reforming performance is significantly dependent on A/F, W/F and concentration of C2+ hydrocarbons in inlet fuel. Fuels containing higher C2+ hydrocarbons concentration have optimum performance in terms of more H2 at higher A/F and W/F but lower conversion efficiency. Good performance for ATR of fuel containing 15%–20% C2H6 can be achieved at A/F=5–7 and W/F=4–6, much higher than that for optimum performance of ATR of methane (A/F=3,W/F=2–2.5). CO2 in the inlet fuel does not have significant effect on the reversed water–gas shift reaction. Its effect on reforming performance is mainly due to the dilution of inlet fuel and products. 相似文献