Reforming Reaction Research Articles

Exploring the Challenges of Calcium Looping Integrated with Methane Bireforming for Enhanced Carbon Capture and Utilization.

The urgent need to mitigate greenhouse gas emissions and combat climate change has driven research in carbon capture and utilization (CCU) technologies. Among these, calcium looping (CaL) has emerged as a prominent candidate for CO2 capture. This study aimed to explore the novel integration of CaL with methane bireforming (BRM) using CaO-Ni/CeO2 as dual-function material (DFM) and investigated the challenges and opportunities associated with the process. Implementing a calcium looping-bireforming (CaL-BRM) process revealed distinct differences compared to methane dry reforming (DRM). Notably, methane conversion occurred at higher temperatures, likely due to competition with the formation of Ca(OH)2. Meanwhile, the conversion of CO2 was delayed, possibly because hydroxide species on the CaO surfaces hindered the availability of CO2 for methane reforming. To address these challenges, Ni/CeO2 and CaO-Ni/CeO2 catalysts were employed in conventional catalytic gas-phase BRM and methane steam reforming (SRM) reactions. The results demonstrated that the presence of CaO significantly influenced BRM efficiency due to the Ca(OH)2 formation, as was evident by the results of the characterization on the postreaction catalysts and the parallel study of SRM. This study contributes valuable insights into the feasibility and potential of CaL-BRM, advancing the development of sustainable CCU technologies.

Simulation And Optimization Of Hydrogen Production By Steam Reforming Of Natural Gas

Hydrogen (H2) production through natural gas steam reforming is widely adopted due to its cost-effectiveness and energy efficiency. A simulation and optimization study was performed on an industrial natural gas steam reforming system using Aspen Hysys V12 software to optimize this process. The study focused on optimizing various parameters, including the Reformer Reactor, Water Gas Shift Reactor, and purification units such as the Separator and Pressure Swing Adsorption (PSA). The Reformer and Water Gas Shift reactors were set at 900 °C and 300 °C, respectively, to maximize hydrogen production. Under specific conditions of 5 atm pressure and a steam-to-carbon ratio (S/C) of 2.5, the process achieved a hydrogen production rate of 402.2 kg/h. The treatment zone effectively eliminated ~ 100% of undesirable CO2 and CO gases, with only trace amounts of CH4 and H2 remaining in the waste gases. Additionally, the PSA unit efficiently removed ~ 100% of the water from the separator, ensuring water-free dry gases were sent to the PSA unit. The integration of heating and cooling heat exchange units reduced energy consumption by approximately 51.6%. After the removal of undesired gases in our PSA unit, the production yield for the final product (H2, based on dry gas inlet to PSA) is 77.83%, resulting in 100% pure dry H2. In the waste gas outlet (tail gas) of PSA a composition (22.17%), includes CO, CO, H2O, and CH4. Resulting high-quality hydrogen is well-suited for a wide range of applications, including fuel cells, petroleum refining, natural gas refineries, and petrochemical processes.

ZnFexAl2-xO4 spinel supported PdZnβ bifunctional catalyst for methanol steam reforming

PdZnβ alloy catalysts, long regarded as a very promising copper replacement, not only possess copper-like reactivity, but also have superior thermal and chemical stability as well as non-pyrophoric nature that copper catalysts lack. In this contribution, we successfully synthesized the ZnFexAl2-xO4 (x = 0.05–0.2) spinel support, i.e., by replacing Al with a small amount of Fe in ZnAl2O4 spinel. The synthesized support, featuring a high surface area and superior stability, enabled the PdZnβ alloy formation at extremely low Pd loadings (e.g., 1000 ppm Pd), which shows high reactivity and CO2 selectivity toward methanol steam reforming (MSR) reaction. Moreover, it has the unique advantage of constructing bi-functional sites with a specific interfacial structure like PdZn/Fe2O3, the latter of which can effectively enhance water dissociation. Thanks to the synergetic effect, the 0.1 wt% Pd/ZnFe0.1Al1.9O4 catalyst exhibits a much higher ATOF value during the MSR reaction than the 0.1 wt% Pd/ZnAl2O4 counterpart, demonstrating excellent atomic utilization efficiency of noble metal and great potential in the practical application.

Optimization of MxOy (La2O3 or Gd2O3) content in Rh/MxOy-Al2O3 catalyst formulation for the propane steam reforming reaction

Heading full speed towards the extensive use of H2 for humanity's energy needs, blue hydrogen production from light hydrocarbons is one of the most promising alternatives. In this study the production of hydrogen through propane steam reforming (PSR) reaction is investigated over Rh nanoparticles dispersed on MxOy-Al2O3 supports of variable MxOy (M: La, Gd) content towards optimizing catalytic performance. The intrinsic activity and the formation of intermediate CH4 are markedly affected by varying MxOy content passing through a maximum for 10 wt% La2O3 or Gd2O3. Up to 8- and 3.5-fold increases in turnover frequency (TOF) at 400 °C are achieved on these optimally loaded with La2O3 and Gd2O3 catalysts, respectively, accompanied by more than two-fold higher H2 yields. The reducibility of both rhodium species and the MxOy-Al2O3 support strongly depends on the MxOy content, which then determines the catalytic activity. In situ diffuse reflectance infrared furrier transform spectroscopy (DRIFTS) experiments revealed that CHx species generated by the dissociative adsorption of propane interact either with H2 yielding CH4 and/or with hydroxyl groups producing formate species and eventually COx and H2 in a manner which depends on MxOy content. However, the latter path is over-favored for samples with 20 wt% MxOy possessing excessive reducibility, and in combination to an over-strengthening of formates adsorption, the conversion rate to COx and H2 is strongly inhibited. Scaling-up the fabrication of the most active Rh/10%La2O3-Al2O3 catalyst at higher application readiness (structured as pellets) and testing under realistic conditions revealed its suitability for propane reformers.

Renewable Hydrogen Production with Steam Reforming of Ethanol Using Siliceous Mesocellular Foam‐Supported Nickel Catalysts

Nickel (Ni) catalysts loaded on siliceous mesocellular foam (MCF‐S) are synthesized via the wet impregnation method with 3, 5, 10, and 15 wt% NiO loadings and different aging levels (no, partial, and full ageing) to determine how both factors affect the progress of the ethanol steam reforming (ESR) reaction. After extensive material characterization testing to determine material porosity, crystallinity, and Ni metal particle size and spatial location, as well as reaction testing at 300–700 °C and 4 H2O: 1 EtOH molar ratio, the fully aged 10 wt% Ni/MCF‐S possesses the strongest structural stability and catalytic activity, reaching 100% EtOH conversion and 68% H2 selectivity at 700 °C. The aging disperses and embeds more Ni nanoparticles within the walls of the mesopores, which promote the ESR reaction from easier diffusion and more active site contact within the pores. Furthermore, the catalyst reveals little signs of deactivation, as the structure remains virtually unchanged, and any coke formed is on the silica support and not over the Ni nanoparticles after the ESR reaction. Such results have demonstrated a proven applicability for ESR and a further need to research about aging effects toward improving structural properties and the catalytic reaction activity.

Numerical study on effects of CH4–CO2 internal reforming on electrochemical performance and carbon deposition of solid oxide fuel cell

CH4–CO2 fueled solid oxide fuel cells (SOFCs) are the high-efficiency and low-carbon power generation technology. However, carbon deposition severely hinders its application. Here, the numerical model considering the complex anode CH4 internal reforming reactions, H2 electrochemical reaction, gas diffusion and charge transfer of SOFC using CH4–CO2 fuel has been established. The CH4–CO2 internal reforming and electrochemical reactions of SOFC under different CO2/CH4 ratios and temperatures are studied to reveal the optimal operating conditions. The distributions of different reaction rates, gas components and carbon deposition activity at the anode are analyzed. The results show that the increase of CO2 concentration can decrease the carbon activity but also cause the decrease of electrochemical performance. It is found that the good comprehensive performances including power density, carbon activity and methane conversion rate can be achieved under the CO2/CH4 molar ratio of 1. The thermodynamic calculation of three different methane reforming modes shows that CH4–CO2 reforming leads to the greatest carbon deposition risk compared with CH4–H2O and CH4–O2 reforming, implying the importance of anti-carbon for CH4–CO2 fueled SOFC.

Experimental investigation on in-situ hydrogen generation from depleted heavy oil reservoir by gasification

Fossil energy has been confirmed as the primary raw material for hydrogen generation in chemical factories. In-situ hydrogen generation from depleted oil reservoirs has been considered a prominent technology for hydrogen generation, accompanied by harmful gas storage, over the past few years. In this study, the effects of temperature, reaction time, distinct porous media, and oil/water ratio on hydrogen generation were investigated by simulating in-situ heavy oil gasification using high-temperature and high-pressure reactors. As indicated by the results, besides hydrogen, methane and carbon dioxide were also largely generated in the gasification process through water gas shift, oxidation, aquathermolysis, pyrolysis, and so forth. The result suggested that temperature and oil/water ratio exerted relatively significant effects on hydrogen generation due to the boosted forward reaction of water gas shift and steam reforming. Moreover, oxygen would prefer an oxidation reaction with oil instead of hydrogen. It was expressed that the hydrogen fraction decreased and remained constant as residence time went on due to less carbon monoxide generation, and arriving at equilibrium, whereas the gas yield tend to increase. The metallic oxides notably catalyzed hydrogen generation. Some novel insights gained in this study are conducive to achieving high-efficiency hydrogen generation through in-situ heavy oil gasification.

Direct steam reforming of the product gas from ethanol gasification with supercritical water

A continuous process for producing hydrogen from the gasification of ethanol with supercritical water (SCWG) is investigated, which involves a fixed bed steam methane reforming (SMR) reactor downstream of the SCWG reactor. Increasing temperature and decreasing space velocity in the SMR reactor resulted in increased hydrogen concentration and methane conversion. The catalyst activity was more affected at low than high pressures, presumably due to the kinetics of the SMR reaction. The significant increase in total hydrogen yield based on ethanol in the feed showed the importance of installing the reformer after gasification. The excessive steam from the SCWG reactor helped to prevent carbon formation, but it might have resulted in the sintering of the active metal. A long-time experiment proved the stability of the catalyst up to 49 h of time on stream (TOS) with a minor decrease in methane conversion from 84% to 78%.

Topology optimization of catalyst bed structure for a solar steam methane reforming reactor aiming at improved conversion efficiency and hydrogen yield

This study optimized the distribution of catalysts porosity for solar steam methane reforming (SMR) reactor using the topology optimization with different objective functions. The optimized structures were similar, wherein dense catalysts were filled in the high-temperature region at the front of the reactor which increased the contact area between reactants and catalysts, and sparse metal foam catalysts were filled at the rear, which was conducive to reducing the flow resistance and facilitating the collection of products. To facilitate the filling in the actual production process, the optimized structure was simplified, and the simplification structure improved the hydrogen production by 6.84%–22.33% and the methane conversion by 6.54%–11.49% under different working conditions compared with the uniform distribution structure. By adjusting the porosity distribution of the catalysts, the temperature field of optimized reactor conformed to the principle of minimum Gibbs free energy (Gmin) and provided guidance for improving the solar SMR reactor performance.

Biogas dry reforming over nickel-silica sandwiched core–shell catalysts with various shell thicknesses

A series of nickel-silica sandwiched catalysts were synthesized to investigate the effect of shell thicknesses on the reaction of dry reforming. The thicknesses of the silica shell were adjusted by TEOS content and coating time of the silica shell. The outcomes exhibited that encapsulating the Ni-SiO2 catalyst by mesoporous silica shell effectively decreased carbon formation. Higher carbon resistance property of the nickel-silica sandwiched catalyst was related to the confined nickel particles by silica shell, which immobilizes metal particles, hampers the agglomeration and prevents uprooting Ni particles by the growing filamentous carbon. The results revealed that the amount of carbon deposition gradually decreased with the augment of TEOS content. The sandwiched catalyst with 2 ml TEOS exhibited high methane and CO2 conversions of 71.5% and 91.5% under CH4/CO2 = 1.5 and T = 700 °C for 20 h, respectively. Also, negligible carbon was observed on the surface of the catalyst and the original structure of the catalyst was well preserved after the stability test. The results revealed that with an increase in coating time, the catalytic activity improved and carbon deposition decreased.

An InOx Surface Enrichment on the Cu Nanoparticles for the Methanol Steam Reforming

AbstractIn the realm of heterogeneous catalysts promoted by indium, indium often covers other active metals, thereby compromising catalytic activity. However, the inhibition mechanism remains poorly understood. In this study, we investigate the interaction between copper (Cu) and indium oxide (InOx), focusing on the role of the Cu−In interface during the methanol steam reforming (MSR) reaction. Utilizing a series of (quasi) in situ characterization techniques, we observe a decrease in intrinsic catalytic activity for MSR on the CuIn/Al2O3 catalyst, which can be attributed to the surface enrichment of InOx on Cu nanoparticles. Moreover, our findings reveal that the enrichment suppresses both the dehydrogenation of *CH3O and the dissociation of H2O, ultimately leading to a reduction in catalytic activity. This discovery has the potential to guide the rational design of enhanced indium‐based catalysts in the future.

Palladium-copper catalyzed decarboxylation/de-cycloalkanonylative coupling reaction to synthesize 9,9-diaryl-xanthenes

An efficient palladium-copper catalyzed regioselective C–C bond cleavage/C–H bond activation/C–C bond reformation reaction to synthesize 9,9-diaryl-xanthenes has been developed. A variety of 9,9-diaryl-xanthenes were synthesized in moderate to good yields by 9H-xanthene-9-carboxylic acid/2-(9H-xanthen-9-yl)-cycloketones and aromatics bearing electron-donating functional groups through the decarboxylation/de-cycloalkanonylative coupling reactions.

Effect of spent fluid catalytic cracking (FCC) catalyst on syngas production from pyrolysis and CO2-assisted gasification of waste tires

With growing demands for improved energy recovery from waste tires, incorporating waste catalysts from different sectors can provide synergistic solution. This paper investigates the effect of using spent fluid catalytic cracking (FCC) catalyst on evolutionary behavior and yield of syngas (CO, H2, and light hydrocarbons), and char and energy yields during pyrolysis and CO2-assisted gasification of waste tires at 900 °C in a fixed-bed semi-batch reactor. The effect of catalyst position (in-situ and quasi-in-situ catalytic modes) and temperature was also examined during catalytic CO2-assited gasification for energy and chemicals production. The results reveal that the presence of spent FCC catalyst resulted in higher syngas and energy yields. The CO2-assisted gasification provided CO-rich syngas with higher yields than pyrolysis. The quasi-in-situ gasification provided increased syngas and energy yields by 24% and 23% respectively, as compared to in-situ catalytic gasification, which revealed that quasi-in-situ catalytic gasification to be more efficient and effective for increased syngas yields. Increasing temperature to 950 °C increased the yields syngas and energy owing to improved reforming and cracking reactions. This viability of utilizing spent FCC catalyst offers improved waste management economics for FCC plants while simultaneously improving the energy recovery from waste tires.

Rapid mapping of alloy surface phase diagrams via Bayesian evolutionary multitasking

Surface phase diagrams (SPDs) are essential for understanding the dependence of surface chemistry on reaction condition. For multi-component systems such as metal alloys, the derivation of such diagrams often relies on separate first-principles global optimization tasks under different reaction conditions. Here we show that this can be significantly accelerated by leveraging the fact that all tasks essentially share a unified configurational search space, and only a single expensive electronic structure calculation is required to evaluate the stabilities of a surface structure under all considered reaction conditions. As a general solution, we propose a Bayesian evolutionary multitasking (BEM) framework combining Bayesian statistics with evolutionary multitasking, which allows efficient mapping of SPDs even for very complex surface systems. As proofs of concept, we showcase the performance of our methods in deriving the alloy SPDs for two heterogeneous catalytic systems: the electrochemical oxygen reduction reaction (ORR) and the gas phase steam methane reforming (SMR) reaction.

Zn-incorporated joule-heated carbon nanofiber aerogel-supported Cu catalyst for hydrogen production via methanol steam reforming

Conventional Cu-based catalysts are affected by disadvantages, such as uneven temperature distribution, non-uniformity of mass and heat transfer, slow heating rate, and difficult replacement. To address these, a three-dimensional (3D) Zn-incorporated Joule-heated carbon nanofiber aerogel (CNFA)-supported Cu catalyst, was prepared via a facile one-pot method. The optimized catalyst, Cu10–Zn10/CNFA, exhibited an 83.1% conversion of CH3OH and 0.01% selectivity of CO at 250 °C. This improvement was due to Zn species acting as both an isolating agent, which inhibited thermal transmigration and aggregation of Cu-containing nanoparticles during heat treatment, and a combining agent, which provided numerous Cu–ZnO interfaces that enabled strong interactions between Cu and ZnO, which improved the activity and stability of the methanol steam reforming (MSR) reaction. This study reveals the feasibility of utilizing Joule-heated CNFA-supported catalysts for MSR reactions and opens a new avenue for designing and fabricating 3D-ordered porous catalysts related to this transformation.

Dynamic modeling, simulation and optimization of the partially-autothermal reforming of biogas in coated monolith channels

A dynamic model is proposed describing a catalyst-coated SiSiC monolithic structure taking as a case study the autothermal reforming of biogas (SCR=3; OCR=0.66) in an adiabatic mode of operation. A single channel 2-D representation is assumed including dimensionless mass and energy transport equations solved in gPROMS platform resembling the performance of the whole monolith by breaking down the channel topology into three computational layers, namely the channel, the porous catalytic washcoat, where catalytic reforming and oxidation reactions take place, and the supporting wall. The model is verified using literature kinetics data in comparison with thermodynamic equilibrium analysis in HSC Chemistry software, which hints an optimization scheme for the optimal washcoat thickness to maximize H2 formation. The optimal values are applied to the three-layer model in order to track the dynamic evolution of the dependent variables of temperature and compositions from start-up of the monolith to the introduction of the biogas-O2 feed at the desired temperature to the response of the system to any disturbances being imposed after steady-state is reached. The overall dynamic model can interpret various aspects of the combined combustion and reforming of biogas in catalytic monolithic structures and can be used as an assistance for experiment design and process optimization.

Thermodynamic and economic analysis of a multi-energy complementary distributed CCHP system coupled with solar thermochemistry and active energy storage regulation process

The combination of distributed energy systems (DES) and solar energy is considered a vital measure to save the usage of fossil energy. A new distributed combined cooling, heating and power (CCHP) system integrated with solar thermochemistry (STC) and energy storage (ES) units is proposed. The methane steam reforming (MSR) reaction is driven by solar energy to produce hydrogen-rich syngas, which is fed with high-efficiency solid oxide fuel cell (SOFC) – micro gas turbine (MGT) to produce electricity. The residual heat of the flue gas drives a double effect lithium bromide unit for cooling and a heat exchanger for heating, while a parabolic trough collector (PTC) is used to supplement cooling and heating supply. Under different weather conditions and user load demands, simulation analysis of the matching between system outputs and user loads is conducted, and the thermodynamic and economic performance are analyzed. The results show that through active energy storage regulation, the new system outputs can meet the hourly user loads with a matching degree of 1. The total exergy efficiencies of the system on typical summer, transition and winter days are 69.93%, 62.03%, and 52.28%, respectively, and the specific CO2 emission rates are 152.57 g/kWh, 191.75 g/kWh, and 234.16 g/kWh, respectively, indicating that the system has higher exergy efficiency and is more environmentally friendly under strong solar radiation. Economic analysis indicates that the capital investment cost is 779.34 k$, and the revenue begins in the 9-th year.

Techno-economic modeling of a novel poly-generation system based on biogas for power, hydrogen, freshwater, and ammonia production

In the current study, a new poly-generation energy system run by biogas steam reforming is proposed and assessed. To dissect the techno-economic feasibility of the offered system, energy, exergy, and sum unit cost of the products (SUCP) are considered as robust indicators for the system appraisal. Also, to acquire enhanced thermodynamic efficiencies, the system has benefited from the careful design of the biogas steam reforming unit, modified Rankine cycle, ammonia synthesis unit, hydrogen generation equipment as well as reverse osmosis unit. It is uncovered that the prepared poly-generation system is qualified to provide 687.4 kW of power, 0.9662 kg/s of freshwater, 0.15 kg/s of hydrogen, and 1.149 kg/s of ammonia. Besides, the energy and exergy efficiencies of the system have been calculated at about 18.9% and 16.9%, respectively with a total exergy destruction rate of 51020.78 kW. Also, following the results of the thermodynamic appraisals, the biogas steam reforming reactor and ammonia synthesis reactor have the highest contributions to inefficiencies happening in the system. Furthermore, from a sweeping sensitivity investigation, the optimum performance of the system appears in a biogas steam reforming reaction temperature of 1050K. Also, the SUCP decreases by about 21 $/GJ by increasing the Biogas Steam Reforming reactor pressure.

Ultra-flexible Al2O3 fibers: A novel catalyst support material for sustainable catalysis

Flexible aluminum oxide (Al2O3) fibers were prepared by the blow spinning method and their potential as a high-temperature catalyst support was investigated. The synthesized Al2O3 fibers exhibited remarkable flexibility in both mechanical compression and recovery tests, which remained intact in a wide temperature range from −196 °C to 1200 °C. Moreover, their low thermal conductivity of 0.030 W K−1∙m−1, demonstrated an outstanding thermal insulation. Subsequently, nickel nanoparticles were uniformly distributed on the surface of the Al2O3 fibers as a self-supporting catalyst using a conventional impregnation method. The resulting self-supporting Ni/Al2O3 catalyst demonstrated remarkable thermo-catalytic performance and re-activation capability at high temperatures for thermocatalytic reaction of dry reforming of methane (DRM). Our findings highlight the potential of pure Al2O3 flexible fibers as a versatile material for various industrial applications, including high-temperature catalysis.

Catalytic behaviour of transition metal carbides of group 5 in the methanol steam reforming

Transition metal carbides of group 5 (G5TMC=VC, NbC and TaC) with similar crystallite sizes were prepared by a sol-gel route. The catalysts were characterized and studied in the methanol steam reforming (MSR) reaction in the temperature range of 573–723 K at atmospheric pressure and using a stoichiometric CH3OH/H2O = 1/1 mole ratio mixture. Under the MSR reaction conditions used, the route of methanol transformation depends on the G5TMC used as catalyst. The catalytic behaviour of VC differs from that of NbC and TaC, which in turn show a similar behaviour. Over VC, methanol is mainly converted to a mixture of H2+CH4, whereas over NbC and TaC the major product obtained is HCHO, formed from the dehydrogenation of methanol.