甲烷水蒸气重整制氢研究进展

氢气由于燃烧发热量高、储量丰富、环境友好,被誉为“21世纪绿色清洁能源”,近年来,甲烷水蒸气重整制氢方法备受关注。但是甲烷重整反应的复杂性及反应机理的不确定性是制约甲烷水蒸气重整制氢工业生产的重要因素。从甲烷水蒸气重整制氢过程、反应机理、热力学分析、催化剂种类以及反应器选择5个方面对重整过程进行了归纳与分析;阐述了甲烷水蒸气重整制氢过程中吉布斯自由能的变化趋势、工况参数对重整反应的影响规律、重整过程反应器的选择、重整反应过程的微观机理以及不同催化剂对重整反应的影响程度;全面总结了甲烷水蒸气重整制氢过程的变化规律;展望了甲烷水蒸气重整制氢的发展前景与研究方向。

基于5kW非共轴聚光型模拟器性能数值研究

文章采用Tracepro软件对一个5 kW小型非共轴聚光型太阳能模拟器建立数学模型,通过实验验证了模型的准确性,并计算得到了太阳能模拟器中聚光镜的结构参数(旋转角度θ、后端开口直径、前端开口直径)和氙灯光源的安装误差(光源离焦、偏转角)对太阳能模拟器焦平面热流密度峰值和辐照不均匀度的影响规律。研究结果表明:太阳能模拟器焦平面热流密度峰值与辐照不均匀度随聚光镜旋转角度呈现逐渐下降的趋势;热流密度峰值与辐照不均匀度随聚光镜后端开口直径增加分别呈下降和上升趋势;热流密度峰值与辐照不均匀度随前端开口直径增加分别呈上升和下降趋势;光源离焦对焦平面热流密度峰值有负影响;光源偏转角度对热流密度峰值和辐照不均匀度几乎无影响。文章研究结果对太阳能模拟器聚光镜结构及汇聚光斑性能优化提供了理论指导。

Current technology development for CO2 utilization into solar fuels and chemicals:A review

The continuous consumption of fossil fuels causes two important impediments including emission of large concentrations of CO2 resulting in global warming and alarming utilization of energy assets.The conversion of greenhouse gas CO2 into solar fuels can be an expedient accomplishment for the solution of both problems,all together.CO2 reutilization into valuable fuels and chemicals is a great challenge of the current century.Owing to limitations in traditional approaches,there have been developed many novel technologies such as photochemical,biochemical,electrochemical,plasma-chemical and solar thermochemical.They are currently being used for CO2 capture,sequestration,and utilization to transform CO2 into valuable products such as syngas,methane,methanol,formic acid,as well as fossil fuel consumption reduction.This review summarizes different traditional and novel thermal technologies used in CO2 conversion with detailed information about their working principle,types,currently adopted methods,developments,conversion rates,products formed,catalysts and operating conditions.Moreover,a comparison of these novel technologies in terms of distinctive key features such as conversion rate,yield,use of earth metals,renewable energy,investment,and operating cost has been provided in order to have a useful review for future research direction.

Analysis of CO_2 utilization into synthesis gas based on solar thermochemical CH_4-reforming

In this study, the solar thermochemical reactor performance for CO_2 utilization into synthesis gas(H_2+ CO) based on CH_4 reforming process was investigated in the context of carbon capture and utilization(CCU) technologies. The P1 radiation heat transfer model is adopted to establish the heat and mass transfer model coupled with thermochemical reaction kinetics. The reactor thermal behavior with direct heat transfer between gaseous reactant and products evolution and the effects of different structural parameters were evaluated. It was found that the reactor has the potential to utilize by ～60% of CO_2 captured with 40% of CH_4 co-fed into syngas(72.9% of H_2 and 27.1% of CO) at 741.31 k W/mof incident radiation heat flux. However, the solar irradiance heat flux and temperature distribution were found to significantly affect the reactant species conversion efficiency and syngas production. The chemical reaction is mainly driven by the thermal energy and higher species conversion into syngas was observed when the temperature distribution at the inner cavity of the reactor was more uniform. Designed a solar thermochemical reactor able to volumetric store concentrated irradiance could highly improve CCU technologies for producing energy-rich chemicals. Besides, the mixture gas inlet velocity, operating pressure and CO_2/CH_4 feeding ratio were crucial to determining the efficiency of CO_2 utilization to solar fuels. Catalytic CO_2-reforming of CH_4 to chemical energy is a promising strategy for an efficient utilization of CO_2 as a renewable carbon source.

Solar-driven photothermal catalytic CO_(2) conversion:a review

It is highly desirable to seek green and sustainable technologies,such as employing photo thermal effects to drive energy catalysis processes to address the high energy demand and associated environmental impacts induced by the current methods.The photothermocatalysis process is an emerging research area with great potential in efficiently converting solar energy through various catalytic reactions.However,achieving simultaneously high conversion efficiency,cyclability,and durability is still a daunting challenge.Thus,tremendous work is still needed to enhance solar photo thermal catalytic conversion and promote its large-scale applications.This review developed the principles of coupling solar photon and thermal fields underlying the photothermal effect,exploration of efficient nanocatalysts,development of optofluidic reactor model,and photo thermal synergistic-driven CO_(2) reduction mechanisms.The ultimate goal was to provide an effective approach that can effectively convert solar energy into photocarriers/hot-electrons and heat,and importantly,can couple them to regulate catalysis reaction pathways toward the production of value-added fuel and chemical energy.

Corrosion evaluation and resistance study of alloys in chloride salts for concentrating solar power plants

Thermal energy storage(TES)systems based on molten salt are widely used in concentrating solar power(CSP)plants.The investigation of the corrosion behavior of alloy materials in molten salt is crucial for the correct selection of alloy materials and the design of TES systems.In this study,the corrosion behavior of 304,310S,316,and In625 alloys in molten chloride salts(27 mol%NaCl-22 mol%KCl-51 mol%MgCl,)was investigated.The evolution of mass loss of the alloy samples with corrosion time and temperature and the analysis of the experimental results by scanning electron microscopy(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD)revealed the corrosion mechanism of the alloy samples in molten chloride salts.The main factors affecting the corrosion of the alloy samples were further analyzed.It was found that the loose multi-layer corrosion was formed on the surface of the corroded alloy samples with the increase in corrosion degree.Moreover,the experimental results.showed that Mo played a positive role in improving the corrosion resistance of the alloy samples because the presence of Mo could inhibit the outward diffusion of alloying element Cr.This work enriches the molten salt corrosion database and provides a reference for the selection of alloy materials for TES systems with potential application in CSP plants.

Self-supported copper-based gas diffusion electrodes improve the local CO_(2)concentration for efficient electrochemical CO_(2)reduction

Electrochemical CO_(2)reduction is a sustainable approach in green chemistry that enables the production of valuable chemicals and fuels while mitigating the environmental impact associated with CO_(2)emissions.Despite its several advantages,this technology suffers from an intrinsically low CO_(2)solubility in aqueous solutions,resulting in a lower local CO_(2)concentration near the electrode,which yields lower current densities and restricts product selectivity.Gas diffusion electrodes(GDEs),particularly those with tubular architectures,can solve these issues by increasing the local CO_(2)concentration and triple-phase interface,providing abundant electroactive sites to achieve superior reaction rates.In this study,robust and self-supported Cu flow-through gas diffusion electrodes(FTGDEs)were synthesized for efficient formate production via electrochemical CO_(2)reduction.They were further compared with traditional Cu electrodes,and it was found that higher local CO_(2)concentration due to improved mass transfer,the abundant surface area available for the generation of the triple-phase interface,and the porous structure of Cu FTGDEs enabled high formate Faradaic efficiency(76%)and current density(265 mA¸cm^(−2))at–0.9 V vs.reversible hydrogen electrode(RHE)in 0.5 mol·L^(−1)KHCO3.The combined phase inversion and calcination process of the Cu FTGDEs helped maintain a stable operation for several hours.The catalytic performance of the Cu FTGDEs was further investigated in a non-gas diffusion configuration to demonstrate the impact of local gas concentration on the activity and performance of electrochemical CO_(2)reduction.This study demonstrates the potential of flow-through gas-diffusion electrodes to enhance reaction kinetics for the highly efficient and selective reduction of CO_(2),offering promising applications in sustainable electrochemical processes.

Analysis of radiation heat transfer and temperature distribu- tions of solar thermochemical reactor for syngas production

This paper investigated radiation heat transfer and temperature distributions of solar thermochemical reactor for syngas production using the finite volume discrete ordinate method （fvDOM） and P1 approximation for radiation heat transfer. Different parameters including absorptivity, emissivity, reflection based radiation scatter- ing, and carrier gas flow inlet velocity that would greatly affect the reactor thermal performance were sufficiently investigated. The fvDOM approximation was used to obtain the radiation intensity distribution along the reactor. The drop in the temperature resulted from the radiation scattering was further investigated using the P1 approx- imation. The results indicated that the reactor temperature difference between the P1 approximation and the fvDOM radiation model was very close under different operating conditions. However, a big temperature difference which increased with an increase in the radiation emissivity due to the thermal non-equilibrium was observed in the radiation inlet region. It was found that the incident radiation flux distribution had a strong impact on the temperature distribution throughout the reactor. This paper revealed that the temperature drop caused by the boundary radiation heat loss should not be neglected for the thermal performance analysis of solar thermochemical reactor.