Partial Oxidation Of Methane Research Articles

Quantifying the Hydration‐Dependent Dynamics of Cu Migration and Activity in Zeolite Omega for the Partial Oxidation of Methane

AbstractCopper‐exchanged zeolite omega (Cu‐omega) is a potent material for the selective conversion of methane‐to‐methanol (MtM) via the oxygen looping approach. However, its performance exhibits substantial variation depending on the operational conditions. Under an isothermal temperature regime, Cu‐omega demonstrates subdued activity below 230 °C, but experiences a remarkable increase in activity at 290 °C. Applying a high‐temperature activation protocol at 450 °C causes a rapid deactivation of the material. This behavioral divergence is investigated by combining reactivity studies, neutron diffraction and in situ high‐resolution anomalous X‐ray powder diffraction (HR‐AXRPD), as well as electron paramagnetic resonance spectroscopy, to reveal that the migration of Cu throughout the framework is the primary cause of these behaviors, which in turn is predominantly governed by the degree of hydration of the system. This work suggests that control over the Cu migration throughout the zeolite framework may be harnessed to significantly increase the activity of Cu‐omega by generating more active sites for the MtM conversion. These results underscore the power of in situ HR‐AXRPD for unraveling the behavior of materials under reaction conditions and suggest that a re‐evaluation of Cu‐zeolites priorly deemed inactive for the MtM conversion across a broader range of conditions and looping protocols may be warranted.

Integrated syngas biorefinery for manufacturing ethylene, acetic acid and vinyl acetate

The paper presents the design of an innovative process for manufacturing sustainable biochemicals, as acetic acid, ethylene and vinyl acetate monomer (VAM), in an integrated syngas biorefinery using renewable feedstock as biomethane and captured CO2. The work is supported by full design and simulation of six plants imbedded in a large process: syngas1 H2/CO 2:1 by catalytic partial oxidation of methane, syngas2 H2/CO 1:1 by dry methane reforming, methanol, acetic acid by carbonylation, ethylene and vinyl acetate. A key contribution is the development of a novel acetic-acid-to-ethylene process starting from syngas. This consists of catalytic hydrogenation of acetic acid (exothermic) followed by catalytic ethanol dehydration (endothermic). The thermal integration of reactors leads to low energy process and superior sustainability measures versus petrochemical and methanol-to-olefin processes. The comprehensive simulation of the integrated biorefinery allows getting consistent mass and energy balances, performing energy analysis and capital cost estimation, and finally delivering reliable sustainability measures. Based on syngas the carbon-yield, mass-yield, carbon footprint (kg CO2/kg product) and energetic requirement (MJ/kg) are 78.6%, 34.7%, 1.6 and 11.2 for ethylene, and 80.8%, 46.8%, 1.5 and 11.9 for VAM. At high biomethane price the ethylene may be costly but manufacturing the higher value VAM is fully profitable.

Synergistic enhancement of methane partial oxidation in heat-recirculating reactor with the composite catalytic effect of Co-based double perovskite and CeO2

Synergistic enhancement of methane partial oxidation in heat-recirculating reactor with the composite catalytic effect of Co-based double perovskite and CeO2

Low chemical-expansion and self-catalytic nickel-substituted strontium cobaltite perovskite four-channel hollow fibre membrane for partial oxidation of methane

In membrane reactors, the thermo-mechanical stability of the membrane determines the operability of the reaction, while the permeability and catalytic performance dictate the reaction process. A high chemical expansion coefficient can exacerbate the mismatch in the thermal expansion behaviour between the two sides of the membrane, potentially resulting in fracture. The low permeability and slow catalytic activity can slow the reaction process and result in an unsatisfactory product composition. Here, a Ba0.5Sr0.5Co0.7Fe0.2Ni0.1O3-δ (BSCFN) four-channel hollow fibre membrane with a low chemical-expansion and high oxygen permeation flux has been successfully fabricated by phase inversion and a one-step thermal process (OSTP). Reaction sintering during the OSTP forms an NiO in-situ exsolution phase on the membrane surface, and A-site stoichiometry excess occurs, improves the oxygen permeation flux, and provides the membrane with self-catalytic ability during the partial oxidation of methane (POM) reactions. Consequently, the BSCFN membrane shows excellent performance; exhibiting an oxygen flux of 11.75 mL cm−2·min−1 at 900 °C. Furthermore, the self-catalytic BSCFN membrane has a good hydrogen production of 10.1 mL cm−2·min−1 during the POM process, which is 7.5 times higher than that of Ba0.5Sr0.5Co0.8Fe0.2O3-δ membranes (1.87 mL cm−2·min−1). This offers a viable strategy for the development of membrane reactor applications.

Improved Catalytic Partial Oxidation of Methane via Lattice Oxygen Modification on Supported Copper Oxide Catalyst System

AbstractThirteen kinds of supported copper oxide catalysts (Cu/MOx, MOx: La2O3, Al2O3, SiO2, TiO2, CeO2, ZrO2, SnO2, SrCO3, BaCO3, Ta2O5, Nb2O5, WO3, and MoO3), which form Cu−O−M sites at the interface between CuOx and MOx or within the complex oxides (CuMOx), were tested for CH4 partial oxidation to find out catalytically active Cu−O−M combinations for production of CH3OH and HCHO. Among the thirteen Cu/MOx tested, Cu/WO3 exhibited the highest total yield of CH3OH and HCHO in a CH4‐O2‐H2O flow reaction at 400 °C. The structural and property analysis of Cu/WO3 revealed the formation of CuWO4, of which the lattice oxygen is active for the partial oxidation of CH4.

Oxygen vacancy induced defect dipoles in BiVO4 for photoelectrocatalytic partial oxidation of methane

A strong driving force for charge separation and transfer in semiconductors is essential for designing effective photoelectrodes for solar energy conversion. While defect engineering and polarization alignment can enhance this process, their potential interference within a photoelectrode remains unclear. Here we show that oxygen vacancies in bismuth vanadate (BiVO4) can create defect dipoles due to a disruption of symmetry. The modified photoelectrodes exhibit a strong correlation between charge separation and transfer capability and external electrical poling, which is not seen in unmodified samples. Applying poling at −150 Volt boosts charge separation and transfer efficiency to over 90%. A photocurrent density of 6.3 mA cm−2 is achieved on the photoelectrode after loading with a nickel-iron oxide-based cocatalyst. Furthermore, using generated holes for methane partial oxidation can produce methanol with a Faradaic efficiency of approximately 6%. These findings provide valuable insights into the photoelectrocatalytic conversion of greenhouse gases into valuable chemical products.

Polydopamine-Mediated Contact-Electro-Catalysis for Efficient Partial Oxidation of Methane.

The direct conversion and efficient utilization of methane pose a critical scientific challenge. Indirect activation via reactive oxygen species (ROS) offers a high probability of contact with methane and conversion efficiency under mild conditions. However, reported product yields are suboptimal due to challenges in activating oxygen and facilitating mass transfer in suspension systems. We propose the use of contact-electro-catalysis (CEC), employing polydopamine (PDA) as a catalyst that undergoes electron transfer with oxygen under ultrasound, generating ROS that drives the partial oxidation of methane (POM). Corresponding experimental results indicate that CH3OH and most HCHO are produced directly from CH4. Furthermore, through in situ characterizations, we have shown that light pretreatment of the catalysts in an oxygenated atmosphere facilitates the forming of more C=O functional groups with strong electron-withdrawing properties, thereby significantly enhancing overall product yields, particularly for CH3OH. Within two hours, product yields reach 1.5 mmol·gcat-1 for HCHO and 0.9 mmol·gcat-1 for CH3OH. This work introduces a novel approach for efficient POM, while highlighting the distinctive catalytic properties of PDA.

Polydopamine‐Mediated Contact‐Electro‐Catalysis for Efficient Partial Oxidation of Methane

The direct conversion and efficient utilization of methane pose a critical scientific challenge. Indirect activation via reactive oxygen species (ROS) offers a high probability of contact with methane and conversion efficiency under mild conditions. However, reported product yields are suboptimal due to challenges in activating oxygen and facilitating mass transfer in suspension systems. We propose the use of contact‐electro‐catalysis (CEC), employing polydopamine (PDA) as a catalyst that undergoes electron transfer with oxygen under ultrasound, generating ROS that drives the partial oxidation of methane (POM). Corresponding experimental results indicate that CH3OH and most HCHO are produced directly from CH4. Furthermore, through in situ characterizations, we have shown that light pretreatment of the catalysts in an oxygenated atmosphere facilitates the forming of more C=O functional groups with strong electron‐withdrawing properties, thereby significantly enhancing overall product yields, particularly for CH3OH. Within two hours, product yields reach 1.5 mmol·gcat−1 for HCHO and 0.9 mmol·gcat−1 for CH3OH. This work introduces a novel approach for efficient POM, while highlighting the distinctive catalytic properties of PDA.

Effect of Ni/Co ratio on Ce-Sc-ZrO2 catalysts for selective H2 production via methane partial oxidation

Partial oxidation of methane (POM) is a promising route for hydrogen production, and achieving a high H2 yield with an H2/CO ratio >3 is highly appealing. Optimization of Ni/Co ratios over Ce-Sc-ZrO2 (CSZ) is investigated for POM reaction and characterized by X-ray diffraction, Raman spectroscopy, temperature-programmed reduction/oxidation/desorption, and transmission electron microscopy. The active site derived from the reduction of “strongly interacted NiO” is responsible for the dissociation of C–H (of CH4), resulting high activity towards POM. 5Ni/CSZ has the highest amount of such active sites and attains the highest activity. 5Co/CSZ catalyst has cobalt-based active sites, and there is an inert carbon deposit during the reaction, causing the least activity. 3.75 wt% Ni and 1.25 wt% Co combination over CSZ support surges the highest density of basicity, oxide vacancy, and adequate amount of active sites derived from “strongly interacted NiO”. The active sites with enhanced metal-support interaction are further grown under exposure to oxidizing gas (O2) and reducing gas (H2) during the POM reaction. The highest density of basicity and oxide vacancy involves more CO2 and H2O in the sequential oxidation of CH4 under indirect pathways. The exclusive involvement of indirect pathways of POM and inhibition of hydrogen consuming reaction (like reverse water gas shift reaction) over 3.75Ni1.25Co/CSZ results into 48 % H2 yield and 3.26 H2/CO ratio up to 24 h time on stream at 600 °C. The H2 yield doubles to ∼97 %, and the H2/CO ratio comes close to 2 over 3.75Ni1.25Co/CSZ catalyst at 900 °C.

Uncertainty Quantification of Linear Scaling, Machine Learning, and Density Functional Theory Derived Thermodynamics for the Catalytic Partial Oxidation of Methane on Rhodium.

Accurate and complete microkinetic models (MKMs) are powerful for anticipating the behavior of complex chemical systems at different operating conditions. In heterogeneous catalysis, they can be further used for the rapid development and screening of new catalysts. Density functional theory (DFT) is often used to calculate the parameters used in MKMs with relatively high fidelity. However, given the high cost of DFT calculations for adsorbates in heterogeneous catalysis, linear scaling relations (LSRs) and machine learning (ML) models were developed to give rapid estimates of the parameters in MKM. Regardless of the method, few studies have attempted to quantify the uncertainty in catalytic MKMs, as the uncertainties are often orders of magnitude larger than those for gas phase models. This study explores uncertainty quantification and Bayesian Parameter Estimation for thermodynamic parameters calculated by DFT, LSRs, and GemNet-OC, a ML model developed under the Open Catalyst Project. A model for catalytic partial oxidation of methane (CPOX) on Rhodium was chosen as a case study, in which the model's thermodynamic parameters and their associated uncertainties were determined using DFT, LSR, and GemNet-OC. Markov Chain Monte Carlo coupled with Ensemble Slice Sampling was used to sample the highest probability density (HPD) region of the posterior and determine the maximum of the a posteriori (MAP) for each thermodynamic parameter included. The optimized microkinetic models for each of the three estimation methods had quite similar mechanisms and agreed well with the experimental data for gas phase mole fractions. Exploration of the HPD region of the posterior further revealed that adsorbed hydroxide and oxygen likely bind on facets other than Rhodium 111. The demonstrated workflow addresses the issue of inaccuracies arising from the integration of data from multiple sources by considering both experimental and computational uncertainties, and further reveals information about the active site that would not have been discovered without considering the posterior.

Synthesis, Characterization, and Attrition Resistance of Kaolin and Boehmite Alumina-Reinforced La0.7Sr0.3FeO3 Perovskite Catalysts for Chemical Looping Partial Oxidation of Methane

Synthesis, Characterization, and Attrition Resistance of Kaolin and Boehmite Alumina-Reinforced La0.7Sr0.3FeO3 Perovskite Catalysts for Chemical Looping Partial Oxidation of Methane

The impact of transition metals (Cr, Mn, and Co) on the performance of the 10%Ni/Al2O3-10%CeO2 catalysts in combined CO2 reforming and partial oxidation of methane

This study explores the efficacy of Cr, Mn, and Co promoters in enhancing the performance of 10%Ni/Al2O3-10%CeO2 catalysts during methane combined reforming process, emphasizing improved metal dispersion and reduced carbon formation. The supports and catalysts were synthesized through mechanochemical and impregnation methods, respectively, and characterized using XRD, BET, TPR, TPO, and FESEM analyses. The synthesized catalysts exhibited a high BET surface area, ranging from 195 to 172 m2 g-1, along with a mesoporous structure characterized by pore sizes between 2 and 12 nm. The introduction of Cr significantly enhanced catalyst performance, resulting in 70.5 % CH4 and 69.1 % CO2 conversions in dry reforming. TPO analysis indicated reduced carbon deposition on promoted catalysts by enhancing Ni dispersion and carbon reactivity. The 10%Ni–3%Cr/Al2O3-10%CeO2 catalyst demonstrated stability over 440 min at 700 °C, achieving 84.9 % CH4 and 68.1 % CO2 conversions in combined reforming. The TPO analysis indicated an absence of carbon deposition on the catalyst surface during combined reforming, which was corroborated by the FESEM analysis. Furthermore, the influence of operating parameters on catalyst efficiency in both dry and combined reforming processes was investigated. As GHSV increased from 8000 to 24,000 ml/h.gcat, CH4 conversion declined in dry reforming and combined reforming, dropping from 77 % to 66 % and from 86 % to 84 %, respectively. Also, in both processes, increasing the oxidizer contents (CH4: CO2 from 2:1 to 1:2, CH4: CO2: O2 from 1:1:0 to 1:1:0.35) led to an increase in CH4 conversion, while CO2 conversion decreased.

Thermodynamic evaluation of solar energy-based methanol and hydrogen production and power generation pathways: A comparative study

This work presents a comparative evaluation of two distinct fuels, methanol and hydrogen, production and power generation routes via fuel cells. The first route includes the methanol production from direct partial oxidation of methane to methanol using solar energy, where the methanol is condensed, stored, and sent to a direct methanol fuel cell. The second route is hydrogen production from solar methane cracking (named as turquoise hydrogen), where heat is supplied from concentrated solar power, and hydrogen is stored and directed to a hydrogen fuel cell. This study aims to provide insights into these fuels' production conditions, storage methods, energy, and exergy efficiencies. The proposed system is simulated using the Engineering Equation Solver software, and a thermodynamic analysis of the entire system, including all the equipment and process streams, is performed. The methanol and hydrogen route’s overall energy and exergy efficiencies are 39.75 %, 38.35 %, 34.21 %, and 33 %, respectively. The highest exergy destruction rate of 1605 kW is observed for the partial oxidation of methane to methanol. The methanol and hydrogen routes generate 32.087 MWh and 11.582 MWh of electricity for 16-hour of fuel cell operation for the same amount of methane feedstock, respectively. Sensitivity analysis has been performed to observe the effects of different parameters, such as operating temperature and mass flow rate of fuels, on the electricity production and energy efficiencies of the systems.

Optimization of methane partial oxidation for hydrogen production with local free space addition: An efficient combination of porous media reactor and thermoelectric conversion system

Thermoelectric technology plays a pivotal role in the efficient conversion and utilization of exhaust heat. Abundant waste heat resources are present in the tail gas of hydrogen production, significantly influenced by combustion characteristics. To investigate the impact of combustion performance on hydrogen yield and power output, an efficient porous media reactor was designed and integrated with a thermoelectric conversion system. The combustion characteristics of a thermoelectric system incorporating unsteady porous media were examined. Furthermore, the effects of the porous media’s structural parameters on temperature distribution, gas concentration, and power generation were analyzed under various operating conditions. The results revealed that radial free space structures exhibited higher hydrogen and methane conversion efficiencies compared to axial free space structures at verge and toroidal positions. However, the height of the radial free space exerted a more substantial influence on temperature distribution and gas production than the size of the free space itself. At a height of 39 mm, hydrogen concentration and yield reached their peak values of 14.5 % and 53 %, respectively. Combustion was found to significantly impact power generation, with a downward shift of the flame resulting in decreased power output. The inlet velocity was observed to affect the thermoelectric generator power, with a maximum steady-state power of 3.95 W achieved at a velocity of 16 cm/s. These findings provide practical guidance for the efficient utilization of industrial waste heat.

Metal Incorporated Zeolites as Heterogeneous Catalysts in the Selective Partial Oxidation of Methane to Methanol: A Review

Metal Incorporated Zeolites as Heterogeneous Catalysts in the Selective Partial Oxidation of Methane to Methanol: A Review

Carbon Dioxide Origin during High-Yield Partial Oxidation of Methane to Protected Methyl Esters

Carbon Dioxide Origin during High-Yield Partial Oxidation of Methane to Protected Methyl Esters

Insights into the Phases Transformation of Copper and Nickel Catalysts during Partial Oxidation and Steam Reforming of Methane

AbstractThe paper shows the structural changes of copper and nickel catalysts in the presence of strong (O2) and weak (H2O) oxidizing agents and their influence on the course of methane conversion. The changes in oxidation states of investigated catalysts were studied during partial oxidation and steam reforming of methane using an X‐ray reactor chamber (XRD) coupled with an online mass spectrometer. Also, the susceptibility of these catalysts to oxidation and reduction by individual reaction components was investigated using TPR, TPO, and in situ XPS techniques. The obtained results indicated the distinct catalytic behavior of copper and nickel catalysts depending on their oxidation state and the importance of coke formation in the activation of the partial oxidation process. The mechanism of re‐reduction of catalysts under reaction conditions and a method to increase the activity of nickel catalysts are proposed.

Quantifying the Hydration-Dependent Dynamics of Cu Migration and Activity in Zeolite Omega for the Partial Oxidation of Methane.

Copper-exchanged zeolite omega (Cu-omega) is a potent material for the selective conversion of methane-to-methanol (MtM) via the oxygen looping approach. However, its performance exhibits substantial variation depending on the operational conditions. Under an isothermal temperature regime, Cu-omega demonstrates subdued activity below 230 °C, but experiences a remarkable increase in activity at 290 °C. Applying a high-temperature activation protocol at 450 °C causes a rapid deactivation of the material. This behavioral divergence is investigated by combining reactivity studies, neutron diffraction and in situ high-resolution anomalous X-ray powder diffraction (HR-AXRPD), as well as electron paramagnetic resonance spectroscopy, to reveal that the migration of Cu throughout the framework is the primary cause of these behaviors, which in turn is predominantly governed by the degree of hydration of the system. This work suggests that control over the Cu migration throughout the zeolite framework may be harnessed to significantly increase the activity of Cu-omega by generating more active sites for the MtM conversion. These results underscore the power of in situ HR-AXRPD for unraveling the behavior of materials under reaction conditions and suggest that a re-evaluation of Cu-zeolites priorly deemed inactive for the MtM conversion across a broader range of conditions and looping protocols may be warranted.

Ni-Sr/TiZr for H2 from methane via POM: Sr loading & optimization.

Achieving remarkable H2 yield with significantly high H2/CO over Ni-based catalysts through partial oxidation of methane (POM) is a realistic approach to depleting the concentration of CH4 and using H2 and CO as synthetic feedstock. This study examined Ni catalysts on titania-zirconia for methane conversion via POM at 600 °C and atmospheric pressure. The addition of strontium to the catalyst was explored to improve its performance. Catalysts were characterized by X-ray diffraction, Raman-infrared-UV-vis spectroscopy, and Temperature-programmed reduction-desorption techniques (TPR, TPD). 2.5 wt% Sr addition induced the formation of the highest concentration of extreme basic sites. Interestingly, over the unpromoted catalyst, active sites are majorly generated by hardly reducible NiO species whereas upon 2.5 wt% promoted Sr promotional addition, most of active sites are derived by easily reducible NiO species. 45% CH4 conversion and 47% H2 yield with H2/CO = 3.5 were achieved over 2.5 wt% Sr promoted 5Ni/30TiO2 + ZrO2 catalyst. These results provide insight into the role of basic sites in enhancing activity through switching indirect pathways over direct pathways for POM. Further process optimization was carried out in the range of 10 000-22 000 SV, 0.35-0.75 O2/CH4, and 600-800 °C reaction temperature over 5Ni2.5Sr/30TiO2 + ZrO2 by using central composite design under response surface methodology. The optimum activity as high as ∼88% CH4 conversion, 86-87% yield of H2, and 2.92H2/CO were predicted and experimentally validated at 800 °C reaction temperature, 0.35O2/CH4 ratio, and 10 000 space velocity.

(Invited) Tailored Electrochemical Interfaces for Renewable Fuels Production

Tailoring the structure of the electrified interface and the electrocatalytically active sites at the atomic and molecular levels is key to elucidating the design principles to develop advanced materials for sustainable energy conversion and storage. This talk will focus on recent strategies to tune the structure-activity-selectivity relationships for oxygen, carbon dioxide/carbon monoxide and methane electrocatalysis to produce renewable fuels.First, I will present our work toward understanding and tuning the structure-property relations for oxygen evolution for the production of green hydrogen in proton exchange membrane water electrolysers. Then, I will show our model studies on well-defined Cu-based surfaces to understand structure-properties relations for the electrochemcial CO2 reduction reaction. We have investigated the effect of electrolyte, pH, and potential dependence for CO reduction on Cu single crystals as well as methods to evaluate the facet distribution on Cu-based catalysts. Finally, I will discuss some strategies for selective oxidation reactions such as partial oxidation of methane to produce liquid fuels such as methanol.