Pure hydrogen production in a Pd-Ag multi-membranes module by methane steam reforming

An experimental test campaign has been carried out in order to investigate the performances in terms of pure hydrogen production of a multi-membrane module coupled with a methane reforming fixed bed reactor. The effect of operating parameters such as the temperature, the pressure, the water/methane feed flow rates and the feed molar ratio has been studied. The hydrogen produced into the traditional reformer has been recovered in the shell side of the membrane module by vacuum pumping. The membrane module consists of 19 Pd/Ag permeator tubes of wall thickness 150 μm, diameter 10 mm and length 250 mm: these dense permeators permitted to separate ultra-pure hydrogen.The experiments have been carried out with the reaction pressure of 100-490 kPa, the temperature of the reformer of 570-720 °C and the temperature of the Pd/Ag membranes module of 300-400 °C. A water/methane stream of molar ratio of 4/1 and 5/1 has been fed into the methane reformer at GSHV of 1547.6 and 1796.1 L_(STP) kg⁻¹ h⁻¹. Hydrogen yield value of about 3 has been measured at reaction pressure of 350 kPa, temperature reformer of 720 °C and methane feed flow rate of 6.445 × 10⁻⁴ mol s⁻¹.     

Performance study of a solid oxide fuel cell and gas turbine hybrid system designed for methane operating with non-designed fuels

This paper presents an analysis of the fuel flexibility of a methane-based solid oxide fuel cell-gas turbine (SOFC-GT) hybrid system. The simulation models of the system are mathematically defined. Special attention is paid to the development of an SOFC thermodynamic model that allows for the calculation of radial temperature gradients. Based on the simulation model, the new design point of system for new fuels is defined first; the steady-state performance of the system fed by different fuels is then discussed. When the hybrid system operates with hydrogen, the net power output at the new design point will decrease to 70% of the methane, while the design net efficiency will decrease to 55%. Similar to hydrogen, the net output power of the ethanol-fueled system will decrease to 88% of the methane value due to the lower cooling effect of steam reforming. However, the net efficiency can remain at 61% at high level due to increased heat recuperation from exhaust gas. To increase the power output of the hybrid system operating with non-design fuels without changing the system configuration, three different measures are introduced and investigated in this paper. The introduced measures can increase the system net power output operating with hydrogen to 94% of the original value at the cost of a lower efficiency of 45%.     

Effect of impregnation phases on the performance of Ni-based anodes for low temperature solid oxide fuel cells

Impregnated nanoparticles are very effective in improving the electrochemical performance of solid oxide fuel cell (SOFC) anodes possibly due to the extension of reaction sites and/or the enhancement of catalytic activity. In this work, samaria-doped ceria (SDC), pure ceria, samaria, and alumina oxides impregnated Ni-based anodes are fabricated to compare the site extending and the catalytic effects. Except for alumina, the impregnation of the other three nano-sized oxides could substantially enhance the performance of the anodes for the hydrogen oxidation reactions. Moreover, single cells with CeO₂ and Sm₂O₃ impregnated anodes could exhibit as great performance as those with SDC impregnated anodes. When the impregnation loading reached the optimal value, 1.7 mmol cm⁻³, these cells exhibit very high performance, with peak power densities around 750 mW cm⁻². The high performance of CeO₂ and Sm₂O₃ impregnated anodes demonstrates that the improved performance are mainly attributed to the significantly improved electrochemical activities of the anodes, but not to the extension of triple-phase-boundary, and wet impregnation is indeed an alternative and effective technique to introduce these nano-sized catalytic active oxides into the anode configuration of SOFCs to enhance cell performance, stability and reliability.     

硅铝配比对镍基催化剂催化废塑料裂解产物的影响

采用浸渍法制备了3种不同硅铝物质的量比的负载镍的催化剂,通过吡啶吸附傅里叶变换红外(FT -IR)和X-衍射(XRD)分别对催化剂的酸性、酸量及晶体类型进行表征,同时考察该催化剂在混合废塑料催化裂 解制燃料油过程中的催化活性。结果表明,随着硅铝物质的量比的降低,催化剂的总酸量增加,产物中气体收率和 积碳收率增加,残渣收率降低,但酸量过高引起废塑料深度裂解,导致产物中汽油馏分收率下降。结果表明,最佳硅 铝物质的量比为1∶3,由此得到的负载镍的2# 催化剂可以使汽油馏份收率大于40%。实验还对催化裂解得到的汽 油馏分进行了气相色谱分析。通过调变催化剂的硅铝物质的量比,可以改变其酸性,从而有利于改善催化剂的选择 性,有利于得到辛烷值较高的汽油馏份。     

Performance of North American Bioreactor Landfills. II: Chemical and Biological Characteristics

The objective of this research was to examine the performance of five North American bioreactor landfills. This paper represents the second of a two-part series and addresses biological and chemical aspects of bioreactor performance including gas production and management, and leachate chemistry. The data support accelerated methane generation at several landfills (k = 0.08–0.21?1/year) relative to the AP-42 default decay rate (k = 0.04?1/year). While the data indicate that gas collection increases at bioreactor landfills, a general relationship between decay rate and moisture added or wet weight water content could not be identified. There was no indication that gas collection increases appreciably when the water content reaches 40%. Most of the leachates at the landfills in this study were commingled from cells operating as a bioreactor and conventionally. Nevertheless, trends in pH and BOD:COD in the bioreactor leachates were consistent with the impacts of enhanced biological activity. Ammonia concentrations also increased over time but remained below levels reported to be inhibitory. For both heavy metals and speciated organic chemicals, there was no indication that bioreactor landfill leachate is significantly different from leachate generated at conventional landfills.     

Macroporous TiO2/carbon composites prepared via a simple soaking process

A new-type composite photocatalyst of three-dimensional ordered macroporous (3DOM) TiO₂/C was prepared and tested in this paper. 3DOM carbon materials were first prepared by colloidal crystal templating process, and then the sols of TiO₂ from tetrabutyl titanate were infiltrated in the macroporous structures via capillary force. After calcinations at nitrogen flow, TiO₂/C composite materials were prepared. The obtained samples were analyzed by SEM, TEM, XRD and BET. The results indicated that macroporous TiO₂/C can remain the three-dimensional ordered structure and TiO₂ nanoparticles distributed in the interior of macropores uniformly. Eventually, 3DOM TiO₂/C materials were used as a new-type photocatalysts to decompose the methyl orange solution under ultraviolet light, which displayed excellent catalytic activity and regenerative ability.     

Investigation of visible light photocatalytic behavior of Bi4V2O11−δ and BIMEVOX (ME = Al, Ga) oxides

A study of photocatalytic properties of Bi₄V₂O_11−δ for the degradation of common organic dyes such as methylene blue (MB) under visible light was carried out. Other identified bismuth based visible light photocatalysts such as Bi₂GaVO₇, Bi₂YVO₈ and Bi₂AlVO₇ were reinvestigated to understand their structural, and photocatalytic properties. Our experiments involving the synthesis of Bi₂YVO₈ indicated merely a mixture of BiYO₃ and BiVO₄, instead of the reported oxide containing bismuth in +3 and +5 oxidation states (J. Luan, et al., Mater. Res. Bull. 43 (2008) 3332). We have further shown the similarity of Bi₂AlVO₇ and Bi₂GaVO₇ photocatalysts with that of the metal ions substituted Bi₄V₂O_11−δ (BIMEVOX; ME = Al, Ga) based on the results of powder X-ray diffraction, UV-vis diffuse reflectance and photocatalytic studies. In general, photocatalytic behavior of Bi₄V₂O_11−δ and Bi₄V_2−xM_xO_11−δ (M = Al, Ga; x = 0.4) were found to be moderate for the decomposition of MB under visible light irradiation.     

废旧不饱和聚酯树脂裂解工艺

对不饱和聚酯树脂(UPR)废料裂解制燃料油技术进行了研究, 系统地考察了热裂解和催化裂解反应工艺条件。试验结果表明, 催化裂解所需反应温度比热裂解反应温度降低了100 ℃, 液相产品收率提高了20 %。试验确定催化裂解反应温度为400 ～ 450 ℃, 反应时间为70 ～ 80 min;剂油质量比为1∶5。试验对4 种催化剂的催化性能进行了评价, 研究表明, 单独使用YB-2 催化剂, 液相产品收率为58 .22%～ 59.14 %;YB-1 和YB-2 混合使用, 最高液相产品收率为68.76%。通过试验证明, 应用催化裂解技术是解决废旧不饱和聚酯树脂对环境污染问题的最佳方案。     

Promotion of active nickel catalysts in methane dry reforming reaction by aluminum addition

Mixed LaNi_xAl_1−xO₃perovskite oxides have been prepared by a sol–gel related method and characterized by X-ray diffraction (XRD), specific surface area measurements and scanning electron microscopy (SEM) coupled to an energy dispersive X-ray spectrometer (EDS) shows the possibility to obtain a solid solution of LaNi_xAl_1−xO₃ (0.1x0.9) with propionic acid as solvent. These systems are highly efficient catalysts for syngas production in dry reforming of methane.     

FCC 汽油馏分在改性HZSM -5 催化剂上的芳构化

采用多种方法对HZSM -5 进行改性, 以沸程75 ～ 120 ℃的催化裂化汽油馏分为原料, 在实验室连续固定床反应装置上考察了采用不同方法改性的HZSM -5 催化剂的芳构化反应性能。实验结果表明, 催化剂的稳定性顺序为HZSM -5相似文献