铁基载氧体煤化学链制氢的强化反应

为促进铁基载氧体的深度还原提高氢气产量,通过优化反应过程形成强化煤化学链制氢(强化煤CLHG)工艺。采用浸渍法制备铁基载氧体;以梅花井烟煤为原料,在固定床上研究煤与铁基载氧体的质量比对强化煤CLHG的影响;对比了三反应器煤CLHG和强化煤CLHG的制氢过程,对不同阶段的铁基载氧体进行XRD表征;对比二反应器、三反应器以及强化煤CLHG在6次循环实验中的碳转化率和氢气产量。结果表明:当煤与载氧体质量比为1:15时,氢气产量最高达1.74 L/g;强化煤CLHG中的铁基载氧体更多地被还原为FeO或Fe,还原程度加深,同时还原阶段的残炭在蒸汽氧化阶段进一步反应,使得氢气产量比三反应器煤CLHG的高18.4%;在6次循环实验中,强化煤CLHG的碳转化率与三反应器煤CLHG的相差不大,远高于二反应器煤CLHG的;强化煤CLHG的氢气产量始终高于二反应器煤CLHG和三反应器煤CLHG的;强化煤CLHG的单次最高氢气产量为1.76 L/g,循环累计氢气产量为9.54 L。强化煤CLHG缩短制氢时间,制氢能力更优异。     

Bimetallic Fe-Mo sulfide/carbon nanocomposites derived from phosphomolybdic acid encapsulated MOF for efficient hydrogen generation

To tackle the energy crisis and achieve more sustainable development,hydrogen as a clean and renew-able energy resource has attracted great interest.Searching for cheap but efficient catalysts for hydrogen production from water splitting is urgently needed.In this report,bimetallic Fe-Mo sulfide/carbon nanocomposites that derived from a polyoxometalate phosphomolybdic acid encapsulated metal-organic framework MIL-100(PMA@MIL-100)have been generated and their applications in electrocatalytic hydrogen generation were explored.The PMA@MIL-100 precursor is formed via a simple one-pot hydrothermal synthesis method and the bimetallic Fe-Mo sulfide/carbon nanocomposites were obtained by chemical vapor sulfurization of PMA@MIL-100 at high temperatures.The nanocomposite samples were fully characterized by a series of techniques including X-ray diffraction,Fourier-transform infrared analysis,thermogravimetric analysis,N2 gas sorption,scanning electron microscopy,transmission elec-tron microscopy,X-ray photoelectron spectroscopy,and were further investigated as electrocatalysts for hydrogen production from water splitting.The hydrogen production activity of the best performed bimetallic Fe-Mo sulfide/carbon nanocomposite exhibits an overpotential of-0.321 V at 10 mA cm-2 and a Tafel slope of 62 mV dec-1 with a 53％reduction in overpotential compared to Mo-free counterpart composite.This dramatic improvement in catalytic performance of the Fe-Mo sulfide/carbon composite is attributed to the homogeneous distribution of the nanosized iron sulfide,MoS2 particles,and the for-mation of Fe-Mo-S phases in the S-doped porous carbon matrix.This work has demonstrated a potential approach to fabricate complex heterogeneous catalytic materials for different applications.     

High temperature removal of hydrogen sulfide using an N-150 sorbent

In this study, an N-150 sorbent was used as a high temperature desulfurization sorbent for the removal of hydrogen sulfide from coal gas in a fixed bed reactor. The results indicate that the N-150 sorbent could be used for H(2)S removal in the tested temperature ranges. Regeneration test also reveals that utilization of the N-150 sorbent maintains up to 85% compared to the fresh sorbent. No significant degeneration occurs on the N-150 sorbent. In addition, various concentrations of H(2)S, H(2) and CO were also considered in the performance test of the N-150 sorbent. Except for H(2)S, H(2) and CO act the important roles in the high temperature desulfurization. By increasing the H(2) concentration, the sulfur capacity of the sorbent decreases and an adverse result is observed in the case of increasing CO concentration. This can be explained via water-shift reaction. On the basis of the instrument analysis, X-ray powder diffraction determination and SEM images with EDS spectrum characterization, residual sulfur is found in the regenerated N-150 sorbent and this sulfur species is sulfate which resulted by incomplete regeneration. The sulfate formation and sintering effect are major reasons to cause activity loss in the sulfidation/regeneration cycles.     

Evaluation of small hydrogen sulfide concentrations in calibrating commercial gas analyzers for hydrogen sulfide

Conclusions Small concentrations (10^–5–10^–2 by volume) of hydrogen sulfide in gas mixtures can be analyzed by means of the photocolorimetric method based on the formation of molybdenum blue by the interaction of hydrogen sulfide with ammonium molybdate in an acidic medium.The optimum conditions for reducing molybdate by hydrogen chloride are provided by a content of 50 mg/ml of ammonium molybdate in the absorbing solution, a sulfuric solution with an acidity of 0.6 N, and a coloration ripening time of 15–20 min.     

Growth kinetics of hydrogen sulfide oxidizing bacteria in corroded concrete from sewers

Hydrogen sulfide oxidation by microbes present on concrete surfaces of sewer pipes is a key process in sewer corrosion. The growth of aerobic sulfur oxidizing bacteria from corroded concrete surfaces was studied in a batch reactor. Samples of corrosion products, containing sulfur oxidizing bacteria, were suspended in aqueous solution at pH similar to that of corroded concrete. Hydrogen sulfide was supplied to the reactor to provide the source of reduced sulfur. The removal of hydrogen sulfide and oxygen was monitored. The utilization rates of both hydrogen sulfide and oxygen suggested exponential bacterial growth with median growth rates of 1.25 d(-1) and 1.33 d(-1) as determined from the utilization rates of hydrogen sulfide and oxygen, respectively. Elemental sulfur was found to be the immediate product of the hydrogen sulfide oxidation. When exponential growth had been achieved, the addition of hydrogen sulfide was terminated leading to elemental sulfur oxidation. The ratio of consumed sulfur to consumed oxygen suggested that sulfuric acid was the ultimate oxidation product. To the knowledge of the authors, this is the first study to determine the growth rate of bacteria involved in concrete corrosion with hydrogen sulfide as source of reduced sulfur.     

Critical hydrogen concentrations and stresses of hydrogen sulfide cracking of steel

Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 24, No. 2, pp. 57–59, March–April, 1988.     

Photoluminescence of n-GaN: Influence of chemical treatment of the surface using sulfide solutions

Results are presented of the photoluminescence of n-GaN (T=300 K) after chemical treatment of the surface using solutions of inorganic sulfides (Na₂S and (NH₄)₂S) in water or isopropanol. It is shown that the maximum intensity of the photoluminescence spectrum of n-GaN increases after chemical treatment of the surface using alcohol solutions of sulfides and this increase is greater for solutions of the strong-base sulfide Na₂S compared with the weak-base sulfide (NH₄)₂S. Pis’ma Zh. Tekh. Fiz. 24, 90–93 (December 26, 1998)     

Trace detection of hydrogen peroxide vapor using a carbon-nanotube-based chemical sensor

The sensitive detection of hydrogen peroxide in the vapor phase is achieved using a nanochemical sensor consisting of single-walled carbon nanotubes as the sensing material. The interdigitated electrode-based sensor is constructed using a simple and standard microfabrication approach. The test results indicate a sensing capability of 25 ppm and response and recovery times in seconds. The sensor array consisting of 32 sensor elements with variations in sensing materials is capable of discriminating hydrogen peroxide from water and methanol.     

Ru-B催化剂催化NaBH4水解制氢研究

利用化学浸渍-还原法制备出了Ru-B催化剂,考察了催化剂的制备条件和反应条件对Ru-B催化剂催化NaBH4水解制氢性能的影响。结果表明:当活性组分前体RuCl3·6H2O和还原剂NaBH4的物质的量比为1∶7,还原温度为303K时,制得的Ru-B催化剂催化NaBH4水解制氢性能最佳。当催化剂浓度为0.17g/L,反应温度为303K,NaBH4浓度为0.22mol/L,NaOH浓度为0.01mol/L,转速为540r/min时,Ru-B催化剂催化NaBH4水解产氢的速率可达1740mL H2/(min·g)。还发现Ru-B催化剂催化NaBH4水解产氢的速率与催化剂用量呈线性关系,计算得到Ru-B催化剂催化NaBH4水解产氢反应的活化能为23.58kJ/mol。     

Special features of hydrogen embrittlement of structural steels in biogenous hydrogen sulfide

We study the effect of cathodic polarization with simultaneous action of biogenous hydrogen sulfide on the susceptibility of AB-2Sh and St3sp structural steels to hydrogen embrittlement in marine biological media of different activities. Uniform and concentrated components of the plastic deformation caused by stretching of smooth cylindrical specimens at the rate of =10^–1 s^–1 under hydrogen charging conditions are determined. We suggest a method for identification of processes occurring in the neck of a stretched specimen with respect to those that can take place near crack-type defects in submarine constructions.Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 29, No. 5, pp. 81–84, September–October, 1993.     

Selective detection of hydrogen sulfide using copper oxide-doped tin oxide based thick film sensor array

In this work, copper oxide-doped (1, 3 and 5 wt%) tin oxide powders have been synthesised by sol–gel method and thick film sensor array has been developed by screen printing technique for the detection of H₂S gas. Powder X-ray diffraction pattern shows that the tin oxide (SnO₂) doped with 3 wt% copper oxide (CuO) has smaller crystallite size in comparison to 0, 1 and 5 wt% CuO-doped SnO₂. Furthermore, field emission scanning electron microscopy manifests the formation of porous film consisting of loosely interconnected small crystallites. The effect of various amounts of CuO dopant has been studied on the sensing properties of sensor array with respect to hydrogen sulfide (H₂S) gas. It is found that the SnO₂ doped with 3 wt% CuO is extremely sensitive (82%) to H₂S gas at 150 °C, while it is almost insensitive to many other gases, i.e., hydrogen (H₂), carbon monoxide (CO), sulphur dioxide (SO₂) and liquefied petroleum gas (LPG). Moreover, at low concentration of gas, it shows fast recovery as compared to response time. Such high performance of 3 wt% CuO-doped SnO₂ thick film sensor is probably due to the diminishing of the p–n junction and the smallest crystallite size (11 nm) along with porous structure.     

The stability of 100 ppb hydrogen sulfide standards

An experimental study has been performed to determine the factors affecting the stability of hydrogen sulfide calibration mixtures at concentrations below 1 ppm. Quantitative data was obtained that illustrates that material selection and surface treatment are major factors affecting the shelf life of low concentration reactive gas mixtures. With the proper material selection and surface treatment, hydrogen sulfide and carbonyl sulfide standard mixtures on the order of 50-100 ppb can be maintained for at least 18 months.