Partial Oxidation Reforming Research Articles

H2 from biofuels and carriers: gas-phase and surface ethanol conversion pathways on Rh/Al2O3 investigated by annular microreactor coupled with Raman and FTIR spectroscopy

Catalytic Partial Oxidation (CPO) and Steam Reforming of ethanol are studied on Rh/Al2O3. The main goal of the work is the development of a comprehensive methodological approach coupling catalytic activity testing and surface characterization, in order to investigate both ethanol-to-H2 conversion pathways and C-deposits formation.Experiments are performed in an annular reactor and four reaction regimes in CPO are identified: ethanol oxidative dehydrogenation to acetaldehyde (T < 200 °C); total oxidation and initial ethanol O2-assisted ethanol decomposition (200 °C < T < 300 °C); early H2 and CO production for reforming of surface CHx fragments (300 °C < T < 500 °C); development of ethanol steam reforming (T > 500 °C).Adsorbed species and C-deposits are characterized via operando FTIR, ex-situ Raman and TPO. These analyses proved that the different reaction regimes are reflected in continuous changes of catalytic surface coverage, passing from the co-existence of ethanol and O2 at low temperature, to wide C-coverage when O2 is consumed. At 700 °C gasification is favoured and promotes surface cleaning.

Novel High-Performance Catalysts for Partial Oxidation and Dry Reforming of Methane to Synthesis Gas

Novel High-Performance Catalysts for Partial Oxidation and Dry Reforming of Methane to Synthesis Gas

Synthesis of NiO/MgO/ZrO2 catalyst for syngas production from partial oxidation and dry reforming of biogas

This work focuses on a facile NiO/MgO/ZrO2 synthesis protocol for syngas production via partial oxidation and dry reforming of biogas. Herein, performance of the developed catalysts with different amounts of MgO (0–40 %wt. of support) and NiO (10–50 %wt.) on %CH4 conversion, %CO2 conversion, H2/CO ratio, and carbon formation are studied. The results reveal the presence of monoclinic ZrO2 and tetragonal ZrO2 phases with 50%NiO/ZrO2 catalyst synthesized by surface modification technique using carbon derived from urea. Addition of MgO in the catalyst shows ability to stabilize tetragonal ZrO2 phase as well as enhance basic surface of the catalyst. These properties render the adsorption of CO2 molecules on the surface, which subsequently are reduced by carbon, leading to CO production. Appropriated amount of NiO and MgO, which is 30 %wt. NiO and 20 %wt. MgO (relative to ZrO2) can produce syngas having quality (H2/CO molar ratio) of ca. 2.

Enhancement of partial oxidation reformer by the free-section addition for hydrogen production

Hydrogen production by the partial oxidation combustion in porous media provides an efficient utilization for renewable biogas. In this paper, the free section with lengths of 0, 5, 10, 15 mm were designed in the middle of two-section porous media respectively. The effects of free section addition on the temperature distribution and methane conversion were investigated to determine the optimal burner parameters at the operating conditions of different velocities and equivalence ratios. Results indicate that the highest temperature appeared in the free length of 10 mm but the maximum of H2 energy conversion efficiency was in that of 15 mm. For the Al2O3 ceramic foam of 20 PPI, the better heat recirculation and preheating effect were shown between the gas and solid. However, the productions of H2 and CO at the 10 PPI burner reached the highest. With the increasing of equivalence ratio from 1.4 to 1.8, the energy conversion efficiency of syngas rose from 41% to 61% with the 15 mm free length. The appropriate free section addition contributes to improving the reforming efficiency, which provides a new way for the burner design.

Non-catalytic direct conversion of CH4 and CO2 into high-quality syngas

Both partial oxidation and CO2 reforming can theoretically be used to produce syngas from natural gas. In this work, the possibility of combining the two methods is explored by the use of computational fluid dynamics with detailed chemical reaction mechanisms. It is showed that methane partial oxidation reactor being used industrially can be directly used to transfer CH4 and CO2 into syngas. The effect of the ratio, feed velocity and preheating temperature of the reactants are examined. The optimal overall ratio of reactants is 5:4:1 for CH4 to O2 to CO2, and the optimal preheating temperature and inlet velocity is 923 K and 200–300 m/s, respectively. The conversions of CH4 and CO2 are 99.88% and 46.85%, respectively, and the yields of CO and H2 are 90.8% and 65.13%, respectively. Cooling down the product can easily obtain the target product (syngas) from water vapor. These results suggest an economically competitive way to use the two greenhouse gases for the production of syngas.

Propane-fuelled microtubular solid oxide fuel cell stack electrically connected by an anodic rectangular window

A current collecting window (0.4 cm2), without an electrolyte and cathode, is located in the middle of an anode and connected electrically to the cathode of another microtubular solid oxide fuel cell (MTSOFC) when building a short stack. No apparent open-circuit voltage (OCV) drops were observed during 31 thermal cycles for an 8-cell stack using H2 and syngas. Furthermore, 24.1, 53.6 and 103.5 W power levels are achieved employing this current collecting mode at 700 °C for an 8, 10 and 20-cell stack, respectively. The propane-fuelled 8-cell stack has a maximum power density (MPD) of 0.30 W cm−2 when integrated with a catalytic partial oxidation (CPOX) reformer, at a flow rate of 0.32 g min−1 of propane. A Pt-Ru nanoparticle is fabricated by impregnation treatment of the alumina honeycomb ceramic support. The Pt-based catalyst, with an average size of ∼10.0 nm, is well distributed on the surface of the honeycomb ceramic channel. Moreover, Pt-Ru/Al2O3, as a CPOX catalyst, exhibits high propane conversions (94.2%) at 700 °C.

A Critical and Systematic Review of Sustainable Hydrogen Production from Ethanol/Bioethanol: Steam Reforming, Partial Oxidation, and Autothermal Reforming

A Critical and Systematic Review of Sustainable Hydrogen Production from Ethanol/Bioethanol: Steam Reforming, Partial Oxidation, and Autothermal Reforming

Electrochemical promotion of ethanol partial oxidation and reforming reactions for hydrogen production

The electrochemical activation of a Pt-KβAl2O3 catalytic system is studied for hydrogen production from ethanol. The in-situ intercalation of potassium ions onto the catalyst surface under negative polarization leads to hydrogen activation and an increase in the production rate under all explored conditions, observing a reproducible, controllable and reversible effect. Under ethanol partial oxidation conditions, the ions migration promotes oxidation dehydrogenation route vs. ethanol dehydration one. Moreover, the steam addition is evaluated through different reaction conditions: steam reforming, partial oxidation and autothermal reforming. The steam reforming reaction exhibits the highest initial catalytic activity; although a strong deactivation of the catalyst occurs due to carbonaceous species deposition. Comparing partial oxidation and autothermal reforming, the latter one presents the highest catalytic activity and the strongest electrochemical activation effect. These findings contribute to the Electrochemical Promotion of Catalysis phenomenon application to operando tuning the catalyst conversion towards hydrogen production, therefore expanding its application to hydrogen technology.

Numerical prediction of operating characteristics of micro-gas turbine combustor with on-board reformed EGR system using co-simulation model and 1D reduced model

In this study, an on-board reforming gas turbine system was proposed to expend the combustion stability and operating points of as gas turbine combustor aiming for fuel lean condition. On-board reforming does not store the syngas unlike the existing conventional reforming device, but formed syngas as the operating load changes and participates in combustion. In previous research conducted for this study, a concept single nozzle combustor was designed that satisfies the thermal output of 150 kW and the turbine inlet temperature of 1200 K. In addition, by designing a non-catalytic partial oxidation-based concept reformer, syngas formation was confirmed in various operation points. In previous research, closed-loop analysis was performed to analyze the independent effects of combustor and reformer. However, in this study, open-loop analysis that simulates the combustor and reformer simultaneously was performed to analyze the effect of the combined system at various operating points. As a result, improved combustion was confirmed by the generation of OH radicals when the oxidizing agent was diluted with increasing hydrogen content. This is similar to the lean OH radical distribution in a low-oxidizing environment, which is the basic characteristics of moderate or intense low-oxygen dilution combustion. The reformer analyzed the reaction by changing the reformate fuel inlet velocity. Through this, it was confirmed that the mixedness inside the reformer improved as the reformate fuel inlet velocity. Finally, to calculate the efficiency of the hydrogen addition operating points under various conditions, suitable operating points were derived by comparison with conventional partial oxidation reforming. The operating range of moderate or intense low oxygen dilution combustion in an on-board reforming gas turbine system was numerically predicted. This is expected to greatly contribute to the study to improve the stability of moderate or intensive low oxygen dilution combustion in the future.

An equilibrium analysis of hydrogen production from ethanol-gasoline fuel blends reforming

A hydrogen concentration from ethanol-gasoline blends reforming processes plays a role in exhausted gas recirculation (EGR) that enhanced engine performance and aftertreatment system of gasoline direct injection (GDI) engine. An equilibrium model is widely used as a primary tool to determine a level of hydrogen content from reforming process. Thus, in this work, the equilibrium analysis of hydrogen production is investigated using STANJAN program. Three main reactions (Partial Oxidation Reforming (POx), steam reforming (SRM) and autothermal reforming (ATR)) are studied here. Three commercial ethanol-gasoline blends are studies here (E10, E20 and E85). The effect of reaction temperature, steam to fuel ratio (S/F) and oxygen to fuel ratios (O2/F) are investigated. The results show that the optimum condition for POx is achieved at O2/F ratio of 3 for E10 and E20 and 0.75 for E85. For SRM, the optimum condition for H2 production at temperature 200–500 °C are achieved with S/F ratio of 10–12 for E10 and E20, while E85 can be obtained at S/F ratio of 6–8. Under these conditions, the maximum hydrogen yield (∼30 vol%) are reached with temperature 500 °C. In case of ATR, the highest H2 yield (approximately 25 vol%) is achieved at temperature 500 °C with S/F ratio of 8 for E10 and E20 fuels and 4 for E85 fuel. The highest H2 yields from real exhausted gas reforming are 42 to 55 % vol. Thus, this possibility of on-board hydrogen production via gasoline - ethanol fuel blends reforming operates in GDI engine.

Comparison and optimization of different fuel processing options for biogas-fed solid-oxide fuel cell plants

The biogas needs to be reformed before electro-chemical conversion in the solid-oxide fuel cell, which can be promoted efficiently with wise thermal management and reforming conditions. To ensure the system safety and catalysts durability, additional mineral-bearing water and carbon deposition should be avoided. This paper conducted a detailed biogas-SOFC CHP system analysis considering four layouts, featuring hot and cold recirculation of the anode off-gas, partial oxidation and complete internal reforming. The process optimization and sensitivity analysis are performed with the design variables including the recirculation ratio, and external reformer temperature. The anode supported SOFC operates at 800 °C and 0.4 A/cm2 current density. The results show that pre-reforming with hot recirculation and cold recirculation schemes achieve the highest system efficiency between 56% and 63%. The pre-reforming with hot recirculation scheme has a broader self-sufficient water range eliminating the carbon deposition risk at the recirculation ratio of 42–78% and reforming temperature of 400–650 °C. The no pre-reforming with hot recirculation scheme achieves maximum system efficiency of 58% due to the fuel dilution. Moreover, the partial oxidation with hot recirculation scheme maximum efficiency is limited to 58.9%, given that the partial oxidation reaction is less efficient than steam and dry reforming reactions. The proposed system layout could demonstrate the feasibility of biogas-SOFC with different reforming options especially on small scale with high efficiency and optimal thermal integration opportunities.

Exploring the Effects of Piston Bowl Geometry and Injector Included Angle on Dual-Fuel and Single-Fuel RCCI

Abstract Reactivity control compression ignition (RCCI) is a low-temperature combustion technique that has been proposed to meet the current demand for high thermal efficiency and low engine-out emissions. However, its requirement of two separate fuel systems (i.e., a low-reactivity fuel system and a high-reactivity fuel system) has been one of its major challenges in the last decade. This leads to the single-fuel RCCI concept, where the secondary fuel (reformates of diesel) is generated from the primary fuel (diesel) through catalytic partial oxidation reformation. Following the in-depth analysis of the reformate fuel (reformates of diesel) and its benefit as the low-reactivity fuel with diesel, the effects of the start of injection (SOI) timing of diesel and the energy-based blend ratio were also studied in detail. In this study, the effects of piston profile and the injector included angles were experimentally examined using both conventional fuel pairs (gasoline—diesel and natural gas—diesel) and reformate RCCI. A validated computational fluid dynamics (CFD) model was also used for a better understanding of the experimental trends. Comparing a reentrant bowl piston with a shallow bowl piston at a constant compression ratio and SOI, the latter showed better thermal efficiency, regardless of the fuel combination, due to its 10% lower surface area for the heat transfer. Comparing the 150-degree included angle and 60-degree included angle on the shallow bowl piston, the latter showed better combustion efficiency, regardless of the fuel combination, due to its earlier combustion phasing (at constant SOI timing). The effect was particularly prominent on reformate RCCI because of its incredibly high diluent concentration, which retards the combustion further for the 150-deg injector. Later, using convergecfd, seven different injector included angles were studied at a constant SOI. With the change in injector included angle, the region of the cylinder targeted by the fuel spray varies significantly, and it was found to have a significant impact on the combustion efficiency and the engine-out emissions. As the injector included angle changed from 60-deg to 150-deg, the combustion efficiency increased by 15% and the CO, NOx, and HC emissions decreased by 96%, 70%, and 86%, respectively.

Sizing Design and Simulation of an SOFC Propulsion System for Unmanned Aerial Vehicles

The short flight endurance is one of the key obstacles for the application of unmanned aerial vehicles (UAVs). Appling the fuel cells as the propulsion system of UAVs instead of batteries can increase the energy density and further lead to a longer cruise duration. Compared to other kinds of fuel cells, the solid oxide fuel cell (SOFC) is advantageous for its ability to use hydrocarbon fuels with a much higher energy storage density than hydrogen. In this paper, a SOFC propulsion system is sized and designed for UAV applications. A system model was developed, including a SOFC stack, a catalytic partial oxidation (CPOx) reformer, an after burner, heat exchangers, lithium batteries, etc. The design parameters of the SOFC stack and other components were selected to meet the power and energy demand of the UAV. The power allocation between the SOFC and energy storage components was further studied. The model is proved to be a useful tool for the design and simulation of the UAV-SOFC systems.

Sizing Design and Simulation of an SOFC Propulsion System for Unmanned Aerial Vehicles

The short flight endurance is one of the key obstacles for the application of unmanned aerial vehicles (UAVs). Applying the fuel cells as the propulsion system of UAVs instead of batteries can increase the energy density and further lead to a longer cruise duration. Compared to other kinds of fuel cells, the solid oxide fuel cell (SOFC) is advantageous for its ability to use hydrocarbon fuels with a much higher energy storage density than hydrogen. In this paper, a SOFC propulsion system is sized and designed for UAV applications. The power allocation between the SOFC and energy storage components was further studied. A system model was developed, including an SOFC stack, a catalytic partial oxidation (CPOx) reformer, an after burner, and heat exchangers, etc. The design parameters of the SOFC stack and other components were selected to meet the power and energy demand of the UAV. The model is proved to be a useful tool for the design and simulation of the UAV-SOFC systems.

Heptane dry reforming and coupling with partial oxidation in gliding arc discharge plasma for H2 production

Dry reforming (DR) of n-heptane and coupling of DR with partial oxidation reforming (POR) were investigated through experiments and simulations in a gliding arc discharge (GAD) plasma reactor. The effects of the input power, the molar ratio of oxygen to carbon, and the residence time on the DR process were evaluated according to the conversion rate, product selectivity and the energy yield of hydrogen. The highest CO2 conversion was 42.6%, which was higher than other CO2 splitting technologies in the gliding arc discharge plasma. The coupling of DR and POR achieved better results by adding air to the DR of n-heptane to form a thermal coupling process. Optical emission spectra of n-heptane DR and coupling DR with POR of n-heptane were investigated, respectively. Different reactive species including C2(A3Πg-X3Πu), CO2+(A2Πu-X2Πg), CO(a’3Σ+-a3Π), CO(d3Δ-a3Π) and O+(4P-4S0) were detected. A zero-dimension (0-D) model of heptane DR containing 163 reactions was established in Chemkin to describe the effect of O/C. The 0-D model of coupling DR with POR with 193 reactions was also established.

A mathematical model of two-stage Solid Oxide Fuel Cell, SOFC, stacks for dynamic simulation of Combined Heat and Power system fed by natural gas

Abstract Zero-dimensional two-stage SOFC stacks dynamic model was developed to investigate the effect of operating parameters on stacks performance. The model resolves spatially thermal and thermo-electrochemical behaviour for electrochemical reactions, Catalytic Partial Oxidation and Steam Reforming processes. Design variables and thermo-electrochemical properties were obtained from in-house-fabricated SOFCs carried out by project partners. The completed SOFCs based Combined Heat and Power, CHP, system model was validated by data 18 and numerical results obtained at steady-state mode showing its high-fidelity. A parametric study with respect to key operating parameters including changes in fuel utilization, lambda number and current density values was conducted. The global CHP system dynamic response, in term of the current/voltage delivered by two-stage SOFC stacks, under a fixed fuel utilization, has been determined resulting in greater variations in the voltage of a single cell in the first stack in comparison to the corresponding values in the second stack.

NiO/κ-CeZrO4 functional oxygen carriers with Niδ+ and oxygen vacancy synergy for chemical looping partial oxidation reforming of methane

Chemical looping partial oxidation reforming (CLPOR) technology is an economically attractive, sustainable, and environmental-friendly process strategy of CH4 conversion. In this study, NiO-promoted κ-CeZrO4 functional oxygen carriers (OCs) were designed and synthesized for the CLPOR of methane, with excellent lattice oxygen (LO) transmission performance and structural stability, aiming to reduce the energy penalty and temperature required for methane conversion. The crystalline phase, reaction performance, surface properties and reaction mechanism of the OC were systematically analyzed. In-situ CH4-XPS analysis was further carried out to reveal the internal mechanism with NiO/κ-CeZrO4 and the reason for higher CO selectivity at a low temperature. The methane conversion rate (≥ 80%) and syngas selectivity (≥ 93%) can be obtained under the most of reported reaction conditions (over 850 °C). More importantly, a higher methane conversion rate (52–72%) with syngas selectivity (88–92%) was even able to be achieved at a relative low temperature range 700–800 °C. The excellent performance was attributed to the reducing transmission temperature of the LO and a synergetic effect of Niδ+ and the oxygen vacancies (existed on the surface), thereby inhibiting carbon deposition caused by the excessively fast methane cracking rate under high temperature atmosphere.

Methane conversion into synthesis gas over supported well-defined Pt, Rh or Ru nanoparticles: Effects of metal and support

Partial oxidation (POM) or dry reforming (DRM) of methane are alternatives to steam reforming of methane (SRM) yielding H2 and CO. This manuscript demonstrates the potential of catalysts containing tiny amounts (0.005 wt%) of well-defined Rh, Ru or Pt nanoparticles (NP) supported on Al2O3, La2O3-ZrO2, TiO2, SiO2, Al2O3-SiO2 or MgO-Al2O3 for POM, DRM, POM-DRM or DRM-SRM at 1073 K. Those containing Rh NP on Al2O3, Al2O3-SiO2 or MgO-Al2O3 reveal close to equilibrium conversion in POM/DRM at a contact time of 0.31 s⋅gcat⋅mL−1. Turnover frequency of CH4 conversion depends on the ability of metal to react with gas-phase oxygen. CO and CO2 are primary products of CH4 conversion in POM, with the rate of CO formation exceeding that of CO2. CO is further oxidized to CO2 until O2 is completely consumed. H2 is formed independently on CO in downstream-located catalyst layer where oxygen conversion is complete.

플라즈마-축열버너 부분산화 개질장치

플라즈마-축열버너 부분산화 개질장치

Synergistic catalysis of bi-metals in the reforming of biomass-derived hydrocarbons: A review

Biomass such as ethanol and glycerol has emerged as an alternative feedstock for hydrogen (H2) production in recent years. Ethanol, which is high in H2, can easily be derived from renewable biomass sources, whereas; glycerol is a by-product of biodiesel expected to be surplus in the coming years. Several catalytic reforming routes involving biomass such as steam, CO2, auto thermal, partial oxidation and aqueous-phase reforming can produce syngas or H2. Bimetallic catalysis is one of the potential solutions to reduce carbon formation and catalysts deactivation in reforming processes since it can produce more stable catalysts from the synergistic effect of the combined metals. There are many reviews on catalyst designs and reaction pathways reported in the literature; nevertheless, comparative literature is lacking on the metal configuration of bimetallic catalyst in biomass reforming particularly for ethanol and glycerol reforming reactions. Therefore, studies linked with the synergistic effects of various bi-metal combinations of catalysts used in biomass reforming processes have been reviewed in the paper. Moreover, the study provides data for the application of bimetallic catalyst for industrial biomass processes.