Ecological and Economic Evaluation of Hydrogen Production by Different Water Electrolysis Technologies

The economic and ecological production of green hydrogen by water electrolysis is one of the major challenges within Carbon2Chem® and other power-to-X projects. This paper presents an evaluation of the different water electrolysis technologies with respect to their specific energy demand, carbon footprint and the forecast production costs in 2030. From a current perspective alkaline water electrolysis is evaluated as the most favorable technology for the cost-effective production of low-carbon hydrogen with fluctuating renewables.     

Biogas Plant Upgrade to CO2-Free Technology: A Techno-Economic Case Study

A techno-economic analysis was performed for a biogas plant with in-built algae production. Degradation in the fermenter occurs under mesophilic conditions, to produce 605 Nm³t⁻¹_TS of biogas and 343 Nm³t⁻¹_TS of methane after 50 days. The biogas was combusted in a combined heat-and-power unit to produce heat and electricity. Cultivation of Chlorella vulgaris was done in co-annular photo-bioreactors, with an annual productivity of 107.5 t. For cultivation, both autotrophic and mixotrophic growth were assumed. Detailed mass and energy balances were done. For both conditions of algae growth, the results are approximately the same after a 30-year payback period.     

Techno‐Economic Analysis of Methane Pyrolysis in Molten Metals: Decarbonizing Natural Gas

Methane pyrolysis using a molten metal process to produce hydrogen is compared to steam methane reforming (SMR) for the industrial production of hydrogen. Capital and operating cost models for pyrolysis and SMR were used to generate cash‐flow and production costs for several different molten pyrolysis systems. The economics were most sensitive to the methane conversion and the value obtained for the solid carbon by‐product. The pyrolysis system at 1500 °C is competitive with a carbon tax of $78 t^?1; however, if a catalytic process at 1000 °C were developed using a conventional fired heater, it would be competitive with SMR without a carbon dioxide cost penalty. Several pyrolysis alternatives become competitive with increasing carbon dioxide taxes.     

锂基CO2吸附剂在吸附强化甲烷水蒸汽重整制氢中的应用研究进展

简介了吸附强化甲烷水蒸汽重整制氢的研究背景,重点介绍了新型锂基CO2吸附剂(包括Li2ZrO3、Li4SiO4、Na2ZrO3)在吸附强化甲烷水蒸汽重整制氢中的应用研究进展,对新型吸附剂在吸附强化制氢中的应用研究进行了展望。     

Pure H2 Production by Decomposition of Methane Over Ni Supported on Hydroxyapatite Catalysts

The catalytic decomposition of CH₄ for the production of pure H₂ is carried out over Ni supported on hydroxyapatite [Ca₅(PO₄)₃(OH)] catalysts at 650 °C and atmospheric pressure. CH₄ decomposition activity is decreased with time on stream and finally deactivated completely. The physicochemical properties of the fresh catalysts are characterized by XRD, DTA/TG, TPR and SEM techniques along with CHNS analyses of the used samples. It is found that the 30 wt% Ni/HAp displayed higher H₂ production rates over the other Ni loadings, which is correlated with Ni metal surface area measured by O₂ pulse chemisorption. IICT communication number: 051211.     

以捕集CO_2、风电制氢和CO_2加氢反应构建绿色煤化工之探讨

分析了煤化工和风电产业发展面临的问题,指出应转换角度来看待产业发展中的瓶颈制约,提出了把捕集CO2、风电制氢和CO2加氢反应研究相结合的绿色煤化工的发展思路,供业界参考、探讨。     

NHD用于甲醇生产脱硫脱碳的技术进展

阐述了甲醇生产中NHD法脱硫脱碳的技术进展,脱硫工序针对原料气含硫量不同,分别采用三塔流程配两级闪蒸和二塔流程配两级闪蒸,脱碳工序采取设计节能流程工艺、新型常解气提塔及改变气提方式等措施。实践证明,NHD工艺用于甲醇生产,更具高效节能的特点。     

Dual-phase membrane reactor for hydrogen separation with high tolerance to CO2 and H2S impurities

Catalytic membrane reactors based on oxygen-permeable membranes are recently studied for hydrogen separation because their hydrogen separation rates and separation factors are comparable to those of Pd-based membranes. New membrane materials with high performance and good tolerance to CO₂ and H₂S impurities are highly desired. In this work, a new membrane material Ce_0.85Sm_0.15O_1.925–Sr₂Fe_1.5Mo_0.5O_6-δ (SDC–SFM) was prepared for hydrogen separation. It exhibits high conductivities at low oxygen partial pressures, which is benefit to electron transfer and ion diffusion. A high hydrogen separation rate of 6.6 mL cm⁻² min⁻¹ was obtained on a 0.5-mm-thick membrane coated with Ni/SDC catalyst at 900°C. The membrane reactor was operated steadily for 532 h under atmospheres containing CO₂ and H₂S impurities. Various characterizations reveal that SDC–SFM has good stability in the membrane reactor for hydrogen separation. All facts confirm that SDC–SFM is promising for hydrogen separation in practical applications. © 2018 American Institute of Chemical Engineers AIChE J, 65: 1088–1096, 2019     

Production of H2 for fuel cell applications: methanol steam reforming with sufficiently thorough cleaning of H2 from CO impurity

Methanol steam reforming (MSR) and preferential CO oxidation (PROX) were studied with the view of improving the generation of H₂-rich gases. In MSR, conventional catalysts of methanol synthesis were tested, various Cu-based catalysts were prepared and studied. A theoretic kinetic model (based on the reaction mechanism established using independent methods [1]) is developed and checked out. PROX was studied over various Ru/Al₂O₃ catalysts using a flow “quasi-adiabatic” reactor. On-line recording of gas temperature in the catalyst bed and CO residual concentration at varied reaction conditions allowed to observe ignition and extinction of the catalyst surface and the transition states of the process. It is shown that in the ignition mode a sharp decrease in CO residual concentration can be achieved. The combination of proposed catalyst and the control of the macrokinetic regime of PROX allows high degree of CO removal from gaseous mixtures produced by MSR. Residual CO content in a H₂-rich gaseous mixture can be lowered to < 15 ppm at GHSV∼100 m³/(kg cat)/h and O₂/CO ratio of 1. Obtained data show the possibility of designing a high-throughput set-up for generation of H₂-rich gases from methanol with one-step cleaning from the CO impurity.     

铁基化学链法调节合成气氢碳比及联产氢气的实验研究

利用固定床反应器考察了实验参数对调节用于费托合成的合成气中H2/CO及产氢的影响. 结果表明,500~800℃条件下,合成气(H2/CO为0.5)经过固定床反应器时,出口H2/CO可达0.87~0.53;通过在还原阶段通入适量水蒸汽,可有效提高调节H2/CO的能力,且能增加氧化阶段的产氢量. 此外,还原阶段加入水蒸汽还能有效抑制积碳生成,所制H2纯度接近100%. 在载氧体颗粒中加入石墨作为扩孔剂,可增强颗粒反应活性和稳定性,经过6个循环后,实际产氢量仍保持在理论产氢量的40%以上(不加石墨仅为20%)且仍保持一定的孔结构,而未加石墨的颗粒几乎完全烧结.     

Production of Synthesis Gas via Dry Reforming of Methane over Co‐Based Catalysts: Effect on H2/CO Ratio and Carbon Deposition

The effect of support type on synthesis gas production using Co‐based catalysts supported over TiO₂‐P25, Al₂O₃, SiO₂, and CeO₂ was investigated. The catalysts were prepared by the incipient wet impregnation method and characterized by various techniques for comparison. Experiments were performed in a micro tubular reactor. The results revealed that all Co‐supported catalysts produced synthesis gas ratios of 1 and below and, thus, proved to be well‐suited for methanol and Fischer‐Tropsch syntheses. Co catalysts supported over TiO₂‐P25 and Al₂O₃ provided better synthesis gas ratios and stability performances. The promotion of a Co/TiO₂‐P25 catalyst with Ce had a substantial influence on its catalytic activity and the amount of carbon deposit. A Ce‐promoted catalyst diminished markedly the extent of carbon deposition and thus boosted the performance towards better activity and stability.     

Non‐dispersive absorption for CO2 capture: from the laboratory to industry

Research on capture and recovery of CO₂ has become a critical topic in the development of technological answers to the greenhouse effect. Conventional industrial processes do not fit into the philosophy of process intensification in which a radically new approach should lead to environmentally friendly methods with minimal use of natural resources and production of secondary waste. Conventional processes involve the use of large amounts of toxic organic solvents, such as diethylamine, and large equipment (e.g. absorption columns). Although CO₂ recovery began in industrial operation more than fifty years ago and, in spite of the clear potential for intensified processes demonstrated in the scientific literature, there is no real evidence that new processes for CO₂ recovery will achieve industrial implementation in the short term. In this perspective, the main limitations of membrane systems based on non‐dispersive absorption using porous membranes are outlined, in order to identify the main challenges that still have to be solved to achieve an industrially attractive process for CO₂ recovery. Copyright © 2011 Society of Chemical Industry     

Numerical modelling of rotating packed beds used for CO2 capture processes: A review

Over the last decades, renewable and clean energy sources are being rigorously adopted along with carbon capture technologies to tackle the increasing carbon dioxide (CO₂) concentration level in the environment. CO₂ capture is a quintessential option for tackling global warming issues. In this context, the present paper has reviewed the process intensification equipment called a rotating packed bed (RPB), which is highly industry applicable due to high gravity (HiGee) force. This facilitates strong mass transfer characteristics, a compact design, and low energy consumption. In this review, the current research scenario of RPBs using numerical, computational fluid dynamics (CFD), and mathematical modelling, along with different machine learning approaches in the CO₂ capture process, has been reviewed. The different geometry designs, hydrodynamic characteristics, performance parameters, research methods, and their effects on CO₂ removal efficiency have been discussed. Furthermore, the latest experimental studies are also summarized, especially in the absorption and adsorption domain. Finally, recommendations have been given to support the RPBs in different industrial and commercial applications of CO₂ removal.     

New method of kinetic modeling for CO2 absorption into blended amine systems: A case of MEA/EAE/3DEA1P trisolvent blends

In order to establish an accurate kinetic model for the aqueous amine blends, monoethanolamine (MEA), 2-(ethylamino) ethanol (EAE), and 3-(diethylamino)-1-propanol (3DEA1P) have been chosen as a typical CO₂ absorption trisolvents. The reaction kinetics of aqueous amine blends with carbon dioxide have been investigated first combining experiments and molecular simulations. The stopped-flow technology has been used to obtain the observed reaction rate constant of the overall reactions over the temperature range of 293 to 313 K and at different amine concentrations. A theoretical kinetic model, based on the first-principles quantum-mechanical simulations, has been put forward to interpret the reactions between CO₂ and the aqueous trisolvent amine blends systems. The proposed model, based on the zwitterion mechanism and the base-catalyzed mechanism, shows good prediction with an acceptable absolute average deviation (AAD) of 6.32%, and has been found to be satisfactory in determining the kinetics of the involved complicated reactions.     

Supported Rh catalysts for methane partial oxidation prepared by OM-CVD of Rh(acac)(CO)2

The organometallics chemical vapour deposition (OM-CVD) technique, using Rh(acac)(CO)₂ as a precursor, was employed for the preparation of heterogeneous Rh catalysts supported on low surface area refractory oxides (α-Al₂O₃, ZrO₂, MgO and La₂O₃). Prepared systems were tested in the methane catalytic partial oxidation (CH₄-CPO) reaction in a fixed bed reactor and compared to a reference catalyst prepared from impregnation of Rh₄(CO)₁₂.Catalysts supported on Al₂O₃, ZrO₂ and MgO show better or comparable performances with respect to the reference system.Complete decomposition of Rh precursor during formation of the metal phase under reductive conditions was investigated by TPRD and confirmed by infrared and mass spectrometry data.Supported Rh phase was characterized by CO and H₂ chemisorption, CO-DRIFT spectroscopy and HRTEM microscopy in fresh and aged selected samples. Rh(I) isolated sites and Rh(0) metal particles were found on fresh catalysts; after ageing an extensive reconstruction occurs mainly consisting in a sintering of Rh isolate sites to metal particles but without large increase in mean particles size.Catalytic performances and Rh species balance were found to be dependent on the support material.