Computational Studies on Microreactors for the Decomposition of Formic Acid for Hydrogen Production Using Heterogeneous Catalysts

Sustainable alternatives to conventional fuels have emerged recently, focusing on a hydrogen-based economy. The idea of using hydrogen (H2) as an energy carrier is very promising due to its zero-emission properties. The present study investigates the formic acid (FA) decomposition for H2 generation using a commercial 5 wt.% Pd/C catalyst. Three different 2D microreactor configurations (packed bed, single membrane, and double membrane) were studied using computational fluid dynamics (CFD). Parameters such as temperature, porosity, concentration, and flow rate of reactant were investigated. The packed bed configuration resulted in high conversions, but due to catalyst poisoning by carbon monoxide (CO), the catalytic activity decreased with time. For the single and double membrane microreactors, the same trends were observed, but the double membrane microreactor showed superior performance compared with the other configurations. Conversions higher than 80% were achieved, and even though deactivation decreased the conversion after 1 h of reaction, the selective removal of CO from the system with the use of membranes lead to an increase in the conversion afterwards. These results prove that the incorporation of membranes in the system for the separation of CO is improving the efficiency of the microreactor

Review on recent progress and reactor set-ups for hydrogen production from formic acid decomposition

Hydrogen is a clean and efficient energy carrier, and a hydrogen-based economy is an alternative solution for sustainability. The present work reviews the recent progress for hydrogen's production from various technologies including the generation from fossil fuels, from biomass through biological and thermochemical processes and from water splitting. Although hydrogen is a zero-emission energy when it is used, its cleanness depends on the production pathway that preceded. Hydrogen's storage and transportation has been costly and an unsafe procedure; formic acid (FA; CH2O2), on the other hand, can be generated, transported, and decomposed easily to hydrogen. Formic acid is generated from the hydrogenation of atmospheric carbon dioxide (CO2) and can easily be provided with energy portable devices, vehicles, and other applications. In addition, the most widely known homogeneous and heterogeneous catalysts and reactors for the formic acid reaction are presented. Different types of reactors like, fixed-bed reactors (FBRs), batch reactors, continuously stirred tank reactors (CSTRs) and microreactors were assessed for their performance and reaction's efficiency during formic acid's decomposition

Review on recent progress and reactor set-ups for hydrogen production from formic acid decomposition

Hydrogen is a clean and efficient energy carrier, and a hydrogen-based economy is an alternative solution for sustainability. The present work reviews the recent progress for hydrogen's production from various technologies including the generation from fossil fuels, from biomass through biological and thermo- chemical processes and from water splitting. Although hydrogen is a zero-emission energy when it is used, its cleanness depends on the production pathway that preceded. Hydrogen's storage and transportation has been costly and an unsafe procedure; formic acid (FA; CH2O2), on the other hand, can be generated, transported, and decomposed easily to hydrogen. Formic acid is generated from the hydrogenation of atmospheric carbon dioxide (CO2) and can easily be provided with energy portable devices, vehicles, and other applications. In addition, the most widely known homogeneous and heterogeneous catalysts and reactors for the formic acid reaction are presented. Different types of reactors like, fixed- bed reactors (FBRs), batch reactors, continuously stirred tank reactors (CSTRs) and microreactors were assessed for their performance and reaction's efficiency during formic acid’s decomposition

Different reactor configurations for enhancement of CO2 methanation

Greenhouse gas emissions are a massive concern for scientists to minimize the effect of global warming in the environment. In this study, packed bed, coated wall, and membrane reactors were investigated using three novel nickel catalysts for the methanation of CO2. CFD modelling methodologies were implemented to develop 2D models. The validity of the model was investigated in a previous study where experimental and simulated results in a packed bed reactor were in a good agreement. It was observed that the coated wall reactor had poorer performance compared to the packed bed, approximately 30% difference between the results, as the residence time of the former was lower. In addition, two membrane configurations were proposed, including a membrane packed bed and membrane coated wall reactor. Additional studies were performed in the coated wall reactor revealing that lower flow rates lead to higher conversion values. As for the bed thickness the optimum layer was found to be 1 mm. In both membrane reactor configurations, the effect of the thickness of M1 membrane, which indicates the membrane for the removal of H2O, didn't show difference while the reduction of the thickness of M2 membrane, which indicates the membrane for the removal of CO2, H2 and H2O, showed better results in terms of conversion

Recent progress for hydrogen production from ammonia and hydrous hydrazine decomposition: A review on heterogeneous catalysts

In response to the growing trend of greenhouse gas emissions from the production and use of conventional fuels, COx free hydrogen generation is introduced as an alternative and efficient energy carrier. Due to hydrogen's storage challenges, is more efficient to be produced on-site by other chemical compounds for fuel cell applications. This work outlines the production of hydrogen (H2) from ammonia (NH3) and hydrous hydrazine (N2H4·H2O) catalytic decomposition. Both substances are giving nitrogen (N2) as a by-product, which is not toxic. Moreover, heterogeneous catalysts that were studied through the years are presented. Lastly, a reactoristic view of the ammonia decomposition is provided with different reactors such as catalytic membrane reactors (CMRs), fixed-bed reactors (FBRs) and micro-reactors (MRs) for the evaluation of their performance

Hydrogenation of carbon dioxide (CO2) to fuels in microreactors: a review of set-ups and value-added chemicals production

Climate change, the greenhouse effect and fossil fuel extraction have gained a growing interest in research and industrial circles to provide alternative chemicals and fuel synthesis technologies. Carbon dioxide (CO2) hydrogenation to value-added chemicals using hydrogen (H2) from renewable power (solar, wind) offers a unique solution. From this aspect this review describes the various products, namely methane (C1), methanol, ethanol, dimethyl ether (DME) and hydrocarbons (HCs) originating via CO2 hydrogenation reaction. In addition, conventional reactor units for the CO2 hydrogenation process are explained, as well as different types of microreactors with key pathways to determine catalyst activity and selectivity of the value-added chemicals. Finally, limitations between conventional units and microreactors and future directions for CO2 hydrogenation are detailed and discussed. The benefits of such set-ups in providing platforms that could be utilized in the future for major scale-up and industrial operation are also emphasized.</p

Hydrogenation of carbon dioxide (CO₂) to fuels in microreactors: a review of set-ups and value-added chemicals production

Climate change, the greenhouse effect and fossil fuel extraction have gained a growing interest in research and industrial circles to provide alternative chemicals and fuel synthesis technologies. Carbon dioxide (CO2) hydrogenation to value-added chemicals using hydrogen (H2) from renewable power (solar, wind) offers a unique solution. From this aspect this review describes the various products, namely methane (C1), methanol, ethanol, dimethyl ether (DME) and hydrocarbons (HCs) originating via CO2 hydrogenation reaction. In addition, conventional reactor units for the CO2 hydrogenation process are explained, as well as different types of microreactors with key pathways to determine catalyst activity and selectivity of the value-added chemicals. Finally, limitations between conventional units and microreactors and future directions for CO2 hydrogenation are detailed and discussed. The benefits of such set-ups in providing platforms that could be utilized in the future for major scale-up and industrial operation are also emphasized.Accepted Author ManuscriptChemE/Catalysis Engineerin

Enhancing CO2 methanation over Ni catalysts supported on sol-gel derived Pr2O3-CeO2: An experimental and theoretical investigation

Ni-based catalysts supported on sol-gel prepared Pr-doped CeO2 with varied porosity and nanostructure were tested for the CO2 methanation reaction. It was found that the use of ethylene glycol in the absence of H2O during a modified Pechini synthesis led to a metal oxide support with larger pore size and volume, which was conducive toward the deposition of medium-sized Ni nanoparticles confined into the nanoporous structure. The high Ni dispersion and availability of surface defects and basic sites acted to greatly improve the catalyst's activity. CFD simulations were used to theoretically predict the catalytic performance given the reactor geometry, whereas COMSOL and ASPEN software were employed to design the models. Both modelling approaches (CFD and process simulation) showed a good validation with the experimental results and therefore confirm their ability for applications related to the prediction of the CO2 methanation behaviour