Reviews on Fuel Cell Technology for Valuable Chemicals and Energy Co-Generation

This paper provides a review of co-generation process in fuel cell type reactor to produce valuable chemical compounds along with electricity. The chemicals and energy co-generation processes have been shown to be a promising alternative to conventional reactors and conventional fuel cells with pure water as a byproduct. This paper reviews researches on chemicals and energy co-generation technologies of three types of promising fuel cell i.e. solid oxide fuel cell (SOFC), alkaline fuel cell (AFC), and proton exchange membrane fuel cell (PEMFC). In addition, the research studies on applications of SOFCs, AFCs, and PEMFCs with chemical production (i.e. nitric oxide, formaldehyde, sulfur oxide, C2 hydrocarbons, alcohols, syngas and hydrogen peroxide) were also given. Although, it appears that chemicals and energy co-generation processes have potential to succeed in commercial applications, the development of cheaper catalyst materials with longer stability ,and understanding in thermodynamic are still challenging to improve the overall system performance and enable to use in commercial market

A review of the methanol economy:The fuel cell route

This review presents methanol as a potential renewable alternative to fossil fuels in the fight against climate change. It explores the renewable ways of obtaining methanol and its use in efficient energy systems for a net zero-emission carbon cycle, with a special focus on fuel cells. It investigates the different parts of the carbon cycle from a methanol and fuel cell perspective. In recent years, the potential for a methanol economy has been shown and there has been significant technological advancement of its renewable production and utilization. Even though its full adoption will require further development, it can be produced from renewable electricity and biomass or CO2 capture and can be used in several industrial sectors, which make it an excellent liquid electrofuel for the transition to a sustainable economy. By converting CO2 into liquid fuels, the harmful effects of CO2 emissions from existing industries that still rely on fossil fuels are reduced. The methanol can then be used both in the energy sector and the chemical industry, and become an all-around substitute for petroleum. The scope of this review is to put together the different aspects of methanol as an energy carrier of the future, with particular focus on its renewable production and its use in high-temperature polymer electrolyte fuel cells (HT-PEMFCs) via methanol steam reforming

Modeling of a microfluidic electrochemical cell for the electro-reduction of CO2 to CH3OH

This study focuses on developing a mathematical model for the electrochemical reduction of CO2 into CH3OH in a microfluidic flow cell. The present work is the first attempt to model the electro-reduction of CO2 to alcohols, which is a step forward toward the scale up of the process to industrial operation. The model features a simple geometry of a filter press cell in which the steady state isothermal reduction takes place. All significant physical phenomena occurring inside the cell are taken into account, including mass and charge balances and transport, fluid flow and electrode kinetics. The model is validated and fitted against experimental data and shows an average error of 20.2%. The model quantitatively demonstrated the dominance of the hydrogen evolution over the CH3OH production and the limitations imposed on the process due to the mass transfer of the reactants to the cathode, especially CO2. Also, the model shows that based on the flow pattern of CH3OH, more conductive membrane materials could be used to decrease the potential drop around the membrane in order to improve the process performance

Green synthetic fuels: Renewable routes for the conversion of non-fossil feedstocks into gaseous fuels and their end uses

Innovative renewable routes are potentially able to sustain the transition to a decarbonized energy economy. Green synthetic fuels, including hydrogen and natural gas, are considered viable alternatives to fossil fuels. Indeed, they play a fundamental role in those sectors that are di cult to electrify (e.g., road mobility or high-heat industrial processes), are capable of mitigating problems related to flexibility and instantaneous balance of the electric grid, are suitable for large-size and long-term storage and can be transported through the gas network. This article is an overview of the overall supply chain, including production, transport, storage and end uses. Available fuel conversion technologies use renewable energy for the catalytic conversion of non-fossil feedstocks into hydrogen and syngas. We will show how relevant technologies involve thermochemical, electrochemical and photochemical processes. The syngas quality can be improved by catalytic CO and CO2 methanation reactions for the generation of synthetic natural gas. Finally, the produced gaseous fuels could follow several pathways for transport and lead to different final uses. Therefore, storage alternatives and gas interchangeability requirements for the safe injection of green fuels in the natural gas network and fuel cells are outlined. Nevertheless, the effects of gas quality on combustion emissions and safety are considered

High Temperature Polymer Electrolytes for Hydrogen Fuel Cells and Electrochemical Pumps

Hydrogen fuel cell and separation technologies such as proton exchange membrane fuel cells (PEMFCs) and electrochemical hydrogen pump (ECHP) offer a profound advantage in the transition to a low-carbon economy. An imperative hitch in hydrogen fuel cells and ECHP technology has been the electrocatalyst poisoning by carbon monoxide (CO) and other contaminants in the reactant mixture. By operating, hydrogen fuel cells and ECHPs at high temperatures (\u3e200 °C), the effect of CO adsorption on the electrocatalyst surface could be curtailed. The high-temperature operation of devices necessitates a proton exchange membrane (PEM) to operate under anhydrous conditions. In this work, a new class of anhydrous high-temperature proton exchange membrane (HT-PEM) based on H3PO4 doped PC-PBI membrane blends were examined, and the optimal blend (50:50 ratio) exhibited remarkably high conductivity in a wide temperature range (-70 °C to 240 °C), while also displaying excellent thermal stability and resiliency to water vapor. The new class of HT-PEM enables the operation of hydrogen fuel cells and ECHPs under a wide temperature range, concurrently promoting a better performance by reducing the ASR. The newly developed HT-PEM yielded high-temperature proton exchange membrane fuel cells (HT-PEMFCs) operating with a peak power density of 680 mW cm-2 at 220 ºC. For further advancement in performance, the kinetic and mass transport resistances of the liquid H3PO4 electrode ionomer binders needed to be addressed, for which liquid H3PO4 free – phosphonic acid-functionalized high-temperature polymer electrolytes were explored. The thin-film characterization of the newly synthesized polymer electrolytes was carried on using interdigitated electrode (IDE) platforms decorated with nanoscale platinum electrocatalysts. The enhanced reaction kinetics and gas permeability of liquid H3PO4 free binder enabled an excellent ECHP performance of 1 A cm-2 at 55 mV under pure H2 anode feed and improved fuel cell performance of \u3e0.9 W cm-2 of power density with H2/O2 at 220 °C. The high-temperature operation of ECHP under varying anode hydrogen-hydrocarbon-contaminant mixtures yielded better tolerance to CO and other contaminants in the anode feed, revealing that the performance was driven by hydrogen concentration rather than the concentration of CO in the anode feed mixtures

Bioelectrochemical systems (BESs) towards conversion of carbon monoxide/syngas: A mini-review

Microbial conversion of carbon monoxide (CO)/syngas has been extensively investigated. The microbial conversion of CO/syngas offers numerous advantages over chemically catalyzed processes e.g. the specificity of the biocatalysts, the operation at ambient conditions and high conversion efficiencies. Bioelectrochemical systems (BESs) exploit the capacity of electrochemically active bacteria (EAB) to use insoluble electron acceptors or donors to produce electricity or added-value compounds. Electricity production from different organic sources in BESs has been broadly demonstrated, whereas electricity production from CO/syngas has been very little reported. Acetate oxidation by a consortium of carboxydotrophic and CO-tolerant EAB has been suggested to be the main pathway responsible for indirect electricity generation from CO/syngas. Although electricity production in BESs from several organic sources has been widely investigated, the interest on BESs research is currently moving to the production of added-value compounds by electro-fermentation (EF) processes. EF allows to modify redox balances by the use of electric circuits to fine tune metabolic pathways towards obtaining products with high economic value. Although EF has been widely studied, the potential of use CO-rich gas streams as substrate has been under explored. This review presents and discusses current advances on microbial conversion of CO/syngas in BESs.This study was supported by the Portuguese Foundation for Science and Technology (FCT), within the scope of the project “INNOVsyn - Innovative strategies for syngas fermentation” (POCI-01-0145-FEDER- 033177). This study was also supported by the FCT under the scope of the strategic funding of UIDB/04469/2020 unit and BioTecNorte oper-ation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

Electrochemical Hydrogen Separation via the Solid Acid Electrolyte Cesium Dihydrogen Phosphate

Abundant, inexpensive, high purity molecular hydrogen as a medium for energy distribution is potentially enabling for adoption of alternative electricity generation schemes. Steam reforming of natural gas remains the dominant method of producing large amounts of hydrogen. However, this process also creates by-products, most notably, carbon monoxide and carbon dioxide. Separation to ultra-high purity hydrogen from these syngas reformate streams by traditional methods, such as pressure swing absorption, has its disadvantages including long cycle times, contamination and a large equipment footprint. Alternative methods of hydrogen separation, such as electrochemical pumping, are a viable alternative to this separation dilemma due to their relative simplicity and potential efficiency. The solid-state proton conductor cesium dihydrogen phosphate has shown potential in electrochemical hydrogen separation devices operating on reformed hydrocarbons. In this work, we have synthesized a suite of nanoparticles, including Pt, Pd, Ru, Ni and Cu, supported on carbon for implementation in solid acid electrodes. We evaluate these materials at an intermediate temperature of 250 degrees Celsius for the hydrogen oxidation and reduction reaction, as well the electrooxidation of carbon monoxide. Functionally graded anodes are fabricated to balance CO conversion activity with hydrogen oxidation. These re-engineered anodes are implemented in conjunction with Ni-based cathodes to demonstrate efficient hydrogen separation using ultra low loadings of Pt from syngas-like inputs