Steam Reforming Of Ethanol Research Articles

Ethanol steam reforming for hydrogen production over cobalt catalyst supported on the cerium oxide prepared via the one-step hard template method

This study describes a cobalt catalyst supported on highly porous cerium oxide beads (CeO2-XAD) prepared via the one-step hard template method (using resin Amberlite® XAD7HP as a template) for catalytic steam reforming of ethanol (SRE) for hydrogen production. For comparative purposes, Co catalyst supported on a commercial CeO2 is discussed (Co/CeO2-COM). Comprehensive studies, including TEM, XPS and H2-TPR analysis, reveal that the bare CeO2-XAD consists of tiny particles with highly damaged surfaces, which contain various forms of oxygen. The hierarchical structure of the support beads, fixed after calcination, ensures high mesoporosity favouring the formation of small, evenly dispersed Co3O4 crystallites on CeO2-XAD (∼3 times smaller than in Co/CeO2-COM), which then, after reduction, transformed into fine, homogenously dispersed Co particles that strongly interact with the support. Consequently, the Co catalyst supported on CeO2-XAD exhibits high catalytic activity in SRE (much higher than Co/CeO2-COM). Although both catalysts deactivate during SRE due to carbon deposition the process is less severe for the catalyst with smaller Co crystallites and nanostructured support. This study reveals the huge role played by the appropriate morphology and nanostructure of the catalyst support in SRE since they affect not only the ethanol conversion efficiency but also increase the selectivity of the process and thus limit the deactivation of the catalyst.

Influence of the Interaction of Nickel and Copper with Ceria on Ethanol Steam Reforming over Ni-Cu-CeO2 Catalysts

Catalysts of nickel-ceria, nickel-copper-ceria, and copper-ceria were explored with respect to their properties for hydrogen production through ethanol steam reforming (ESR). They were prepared by coprecipitation of the components within inverse microemulsions to achieve intimate contact between them, and the catalysts were characterized by N2 adsorption measurements, XRD, Raman spectroscopy, TPR, and XPS. The catalysts were tested for the ESR reaction, and they were regenerated with oxygen when significant deactivation took place, as occurred for the copper-containing systems. In contrast, the nickel–ceria catalyst exhibits a high activity and stability despite the formation of an important amount of carbon deposits during the course of the ESR test. The presence of nickel sites, which strongly interact with the ceria support, and which are affected by the presence of copper, and the limitation of copper for C-C bond breaking are invoked to explain the results obtained on the whole.

Atmospheric pressure microwave (915 MHz) plasma for hydrogen production from steam reforming of ethanol

This work presents experimental results on the energy efficiency in hydrogen production using atmospheric microwave plasma (915 MHz) through steam reforming of ethanol. Ethanol was chosen as a liquid hydrogen carrier due to its high hydrogen atom content, low cost, and wide availability. The experimental work began with the maximization of an energy efficiency of the used microwave plasma source. The process of maximization involved determining a position of a movable plunger that ensures the most efficient transfer of microwave energy from a microwave source to the generated plasma in the microwave plasma source. The aim of the investigations was to test the following working conditions of the microwave plasma source: absorbed microwave power PA by the generated plasma (up to 5.4 kW), the carrier gas volumetric flow rate (up to 3900 Nl/h), and the amount of the introduced ethanol vapours on the efficiency of hydrogen production (up to 2.4 kg/h). In the range of tested working conditions, the highest energy yield for hydrogen production achieved a rate of 26.9 g(H2)/kWh, while the highest hydrogen production was 99.3 g(H2)/h.

Effect of Support on Steam Reforming of Ethanol for H2 Production with Copper-Based Catalysts

Effect of Support on Steam Reforming of Ethanol for H2 Production with Copper-Based Catalysts

Hydrogen Production by Steam Reforming of Ethanol and Dry Reforming of Methane with CO2 on Ni/Vermiculite: Stability Improvement via Acid or Base Treatment of the Support.

In this study, vermiculite was explored as a support material for nickel catalysts in two key processes in syngas production: dry reforming of methane with CO2 and steam reforming of ethanol. The vermiculite underwent acid or base treatment, followed by the preparation of Ni catalysts through incipient wetness impregnation. Characterization was conducted using various techniques, including X-ray diffraction (XRD), SEM-EDS, FTIR, and temperature-programmed reduction (H2-TPR). TG-TD analyses were performed to assess the formation of carbon deposits on spent catalysts. The Ni-based catalysts were used in reaction tests without a reduction pre-treatment. Initially, raw vermiculite-supported nickel showed limited catalytic activity in the dry reforming of methane. After acid (Ni/VTA) or base (Ni/VTB) treatment, vermiculite proved to be an effective support for nickel catalysts that displayed outstanding performance, achieving high methane conversion and hydrogen yield. The acidic treatment improved the reduction of nickel species and reduced carbon deposition, outperforming the Ni over alkali treated support. The prepared catalysts were also evaluated in ethanol steam reforming under various conditions including temperature, water/ethanol ratio, and space velocity, with acid-treated catalysts confirming the best performance.

Mesoporous silica encapsulated core-shell NiRh@NiO nanocatalyst for performance-enhanced ethanol steam reforming

A novel mesoporous SiO2 encapsulated core-shell NiRh@NiO nanostructure was constructed to enhance the activity and stability of ethanol steam reforming (ESR). At 550 °C and ethanol-WHSV = 21 h−1, the specific activity and conversion loss (17 h) of NiRh@NiO@m-SiO2 were 0.42 molethanol/(gcat.·h) and 10.9 %. The alloying of NiRh core, dominated NiO in shell, and abundant mesopore of SiO2 were confirmed by systematic characterization techniques. The in situ DRIFTS results indicated that alloying Ni and Rh boosted ethoxide dehydrogenation to acetaldehyde and acetate demethanation to carbonate. ReaxFF molecular dynamics (MD) simulations suggested that NiO shell was conducive to water activation, which, in turn, promoted the conversion of CHxOy species. The SiO2 encapsulation derived confinement effect inhibited both metal core sintering and leaching caused by the filamentous carbon. The abundant mesopores of SiO2 ensured the facile in-diffusion of water and out-diffusion of carbonaceous products, suppressing carbon deposition within the SiO2 encapsulation and the destruction of core-shell structure.

Coupling phyllosilicate and NiCo alloy nanoparticles on sepiolite to enhance stability for hydrogen production by ethanol steam reforming

For hydrogen production from ethanol steam reforming (ESR), The NiCo alloy immobilized on sepiolite (SEP) support by a phyllosilicate precursor was deemed as an effective strategy to improved catalyst stability. The Ni/Co ratio was regulated to optimized the ESR reactivity of the bi-metallic catalysts prepared by the NH4F assisted urea hydrothermal method. The synergy effect of NiCo alloy with a Ni-rich surface on ESR reactivity and anti-deactivation was investigated. The 5Ni10Co/SEP catalyst presented the highest conversion (99.4 %) and H2 yield (68.2 %) at 700 °C, which was benefited from the downsized nanoparticle size and strong metal-support interaction. The proposal structure-activity relationship suggested that the NiCo alloy was exsolved from the phyllosilicate precursor grafted on SEP framework, providing an excellent mitigation for metal sintering. In addition, the synergy of NiCo alloy was elaborated by a combination of enhanced ethanol adsorption/dissociation on Ni sites and restrained methanation on Co sites, offering a 50 h catalyst stability during ESR consisting of the ethanol dehydration route. The developed NiCo alloy catalyst based on SEP support with phyllosilicate precursor provided a prospect on the application to H2 production from ESR over the bimetallic catalysts with simple preparation, high economy and structure stability.

Global Vision of the Reaction and Deactivation Routes in the Ethanol Steam Reforming on a Catalyst Derived from a Ni-Al Spinel.

Ethanol steam reforming (ESR) over a Ni/Al2O3 catalyst prepared by reduction of a NiAl2O4 spinel is a promising alternative route to produce H2 from biomass. This work deepens into the effect of reaction conditions (450-650 °C, a steam/ethanol (S/E) ratio of 3-9, and a weight space time up to 1.3 h) and evaluates the time on stream evolution of the yields of H2, gaseous byproducts (CO, CO2, CH4, C2H4, C2H4O), and formed carbon/coke. The results are explained taking into consideration the thermodynamics, the extent of each individual reaction, and the catalyst deactivation. Up to 600 °C, the predominant intermediate in the H2 formation is C2H4 (formed by ethanol dehydration) with the preferential formation of nanostructured carbon (nanotubes/filaments) by C2H4 decomposition. The deposition of this type of carbon partially deactivates the catalyst, mainly affecting the extent of the C2H4 decomposition causing a sharp decrease in the H2 and carbon yields. Nevertheless, the catalyst reaches a pseudosteady state with an apparent constant activity for other reactions in the kinetic scheme. At 650 °C, C2H4O (formed by the ethanol dehydrogenation) is the main intermediate in the H2 formation, which is the precursor of an amorphous/turbostratic carbon (coke) formation that initially causes a rapid deactivation of the catalyst, affecting the ethanol dehydration and, to a lower extent, the reforming and water gas shift reactions. The increase in the S/E ratio favors the H2 formation, attenuates the catalyst deactivation due to the suppression of the ethanol dehydration to C2H4, and promotes the reforming, water gas shift, and carbon/coke gasification reactions. A H2 yield of 85% stable for 48 h on stream is achieved at 600 °C, with a space time of 0.1 h and an S/E ratio of 9.

Highly stable CuFe1.2Al.8O4 catalyst with low CO selectivity for hydrogen production in HT‐PEMFCs application

AbstractMethanol steam reforming (MSR) is considered as an effective way to provide on‐board hydrogen production technology for fuel cell applications. CuFe1.2Al.8O4 spinel catalyst was synthesized by sol–gel method and the chemical and physical properties were studied in‐depth. X‐ray diffraction, hydrogen‐temperature programmed reduction (H2‐TPR), BET, and scanning electron microscopy were used to characterize the catalysts with reaction times of 20, 50, and 100 h. The results of H2‐TPR showed that 90% of spinel Cu2+ was released after 100 h reaction. BET results show that the specific surface area and pore characteristics of the catalyst have not changed greatly after reaction for 20, 50, and 100 h. Furthermore, in the unsteady‐state test, CuFe1.2Al.8O4 exhibited excellent catalytic activity and thermal stability under long‐term repeated start‐up and stop cycles. At 275°C, the methanol conversion rate remained around 94% and the CO selectivity remained below 1%. Therefore, the catalyst synthesized in this study has excellent stability and low CO selectivity, making it a highly promising on‐board hydrogen production catalyst in the field of HT‐proton exchange membrane fuel cells (PEMFCs).

Ni-CaO-CaZrO3 bi-functional materials for high purity hydrogen production via sorption enhanced steam reforming of ethanol

Ethanol is an ideal hydrogen carrier, which can be converted to hydrogen-rich syn-gas via the steam reforming reaction. Sorption-enhanced steam reforming is a promising approach to produce high-purity hydrogen by mixing the sorbent and catalyst particles. The idea of bi-functional materials, loading both sorption and catalytic site in a single particle, could transform the inter-particle heat-mass transfer to intra-particle heat-mass transfer. This work studied the sorption-enhanced steam reforming of ethanol (SESRE) over Ni-CaO-CaZrO3 bi-functional catalysts containing sorption and catalytic sites. Bi-functional Ni-CaO-CaZrO3 catalysts were synthesized using a simple sol-gel technique. The influence of operating conditions including temperature, steam-to-carbon ratio (S/C) and weight hourly space velocity (WHSV) on Ni10-Ca90Zr10 bi-functional materials were discussed. The operating condition with a temperature of 600 °C, weight hourly space velocity of 0.34 h−1 and steam-to-carbon ratio of 3 was the most suitable reaction condition for hydrogen production in this study. Over the optimized operation conditions, the influence of Ni loadings on hydrogen production performance was further studied. The result indicated that 10 wt% is the best Ni loading in this study for Ni-CaO-CaZrO3, which enables >95% hydrogen purity in the gaseous product in the pre-breakthrough stage, with the longest breakthrough time (90 min). Furthermore, under the best operation conditions, the Ni10-Ca90Zr10 displayed excellent stability over 10 cyclic tests. In the 10th cycle, about 90% hydrogen purity was constantly obtained for at least 60 min during the pre-breakthrough stages. This study demonstrated that the Ni10-Ca90Zr10 bi-functional material is effective and stable for producing hydrogen from ethanol and has the potential to establish a method of generating clean energy with minimal carbon emission.

Effect of calcination temperature on Co/sepiolite catalyst for hydrogen production by ethanol steam reforming: Co speciation from phyllosilicate to spinel

Hydrogen production via ethanol steam reforming (ESR) was conducted over amorphous sepiolite (SEP) supported Co based catalysts, deeming as a green and sustainable strategy for renewable energy. However, the subtle regulation to the ESR reactivity of Co/SEP catalysts still remains a challenge. Given the structure sensitive property of ESR, calcination temperature, as a vital regulation parameter, was used to control the key physicochemical properties of catalysts. By various characterization techniques, the results revealed that a calcination temperature mediated metal-support interaction was manifested in the form of Co speciation evolution. With increasing calcination temperature, the occurrence states of Co species change from Co oxides to Co-phyllosilicate then to Co-Al spinel. The ESR experiments indicated that Co/SEP-600 catalyst possessed a suboptimal activity via a dehydrogenation route and a 50 h stability due to a compromising among Co-phyllosilicate dominated MSI, texture, Co0 nanoparticle size and acid-base property. The further improvement of calcination temperature only brought about a poor stability of Co/SEP-700 with a phase transformation or a low activity of Co/SEP-800 with an irreducible Co-Al spinel. Hence, the interaction type of Co with SEP framework Si/Al atoms determined the ESR reactivity of the catalysts, which was modulated by the calcination temperature. Additionally, abundant graphitic coke deposition on the agglomerated Co0 grains was attributed the weak MSI, such as Co/SEP-400, while a slight coke deposition appeared at Co/SEP-800 with an irreducible Co-Al spinel phase.

Insight into role of Co species on NiCo/CeMgAl for ethanol steam reforming: Enhanced activity and resistance to coke

Bimetallic catalysts with unique geometric and electronic structure exhibit high performance compared to that of monometallic counterparts in the ethanol steam reforming (ESR). Herein, NiCo bimetals supported on CeO2 doped MgAl2O4 (NiCo/CeMgAl) with different ratio of Ni/Co were prepared for ESR. The synergies between Ni and Co in catalytic activities and ability to anti-coking were focused. The results demonstrate Co atoms trend to segregate toward the surface and are oxidized synchronously, forming the Ni-CoO hybrid surface. The reduced Ni particles are beneficial to maintain a stable catalytic activity for the C-C bonds scission, and the CoO particles formed by segregation and irreversible oxidation of Co0 are more conducive to activation of H2O, the resulting OH promotes the transformation of CHx species, which significantly reduces the selectivity of CH4 and prevents the formation of filamentous carbon. Controlling Co content and maintaining a stable M/Mδ+ are critical to balance the C-C bond scission reaction and the CH3* conversion reaction on the NiCo bimetallic catalysts. The optimal catalyst 9Ni1Co/CeMgAl shows the ethanol conversion of 93.9 % at TOS of 100 h, and the average rate of coke formation is 0.50 mgc·gcat-1·h−1.

Si4Al2O2N6 regulating chemical states of Co catalyst for improved hydrogen production from ethanol steam reforming

Tuning the metal-support interaction is a general strategy of regulating the chemical state of catalytic active site for high-efficiency hydrogen production from ethanol steam reforming (ESR) reaction. In this work, a Co catalyst supported on the Si4Al2O2N6 solid solution of Si3N4 and Al2O3 (Co/Si4Al2O2N6) has been developed to effectively catalyze ESR reaction. Our results demonstrate that the Co/Si4Al2O2N6 catalyst exhibits remarkably improved performances as compared with the Co/Si3N4 and Co/Al2O3 catalysts. In the Co/Si4Al2O2N6-catalyzed ESR reaction, ethanol conversion of 97 % has been achieved with hydrogen yield reaching 73 %. Long-time catalytic experiment manifests the Co/Si4Al2O2N6 catalyst possesses excellent durability. X-ray photoelectron spectroscopy (XPS) studies reveal that the enhanced metal-support interaction (MSI) and charge transfer from Si4Al2O2N6 support to Co species in the Co/Si4Al2O2N6 catalyst confer lower valence state on the Co catalyst supported on Si4Al2O2N6, thus promoting the C–C bond cleavage capability, leading to high C1 product yield and boosting the hydrogen-production efficiency. The catalytic mechanism studies explored by in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveal that the Co/Si4Al2O2N6 exhibits a remarkable preference for C1 products over the Co/Si3N4 and Co/Al2O3 catalysts at low reaction temperature, thus resulting in high hydrogen-production efficiency with excellent catalytic durability.

Modeling and simulation of an integrated bioethanol-hydrogen production process

Hydrogen (H2) production from renewable feedstocks such as bioethanol represents one of the sustainable and environmentally benign methods of making the proposed utilization of H2 as energy carrier of the future a reality. However, successful implementation of this technology depends on several factors which include understanding of the technicality, as well as process design and modelling. Generally, this area of research has not received adequate attentions. In this article, an integrated process for producing H2 through starch hydrolysis, fermentation, and ethanol steam reforming (ESTR) process has been proposed. Enzymatic hydrolysis of starch was performed to obtain the fermentable sugar (hydrolysate). In addition, batch fermentation experiments were carried out using a laboratory scale fermenter with yeast (Saccharomyces cerevisiae) culture adapted for anaerobic conversion of the hydrolysate to bioethanol. Subsequently, kinetic data obtained from these experiments was employed to guide thermodynamic modeling of fermentation process which was coupled with the ESTR model and was implemented in the Aspen HYSYS simulator. The results ultimately revealed pertinent information which could find applications in the implementation of the proposed integrated process for bioethanol and H2 production.

Ethanol steam reforming over Ni/ZSM-5 nanosheet for hydrogen production

Ethanol steam reforming over Ni/ZSM-5 nanosheet for hydrogen production

Influence of Ru-substitution on the performance of pyrochlore catalysts in oxidative steam reforming of ethanol

This study reveals that La2Zr2−xRuxO7−δ optimizes hydrogen production and ethanol conversion, particularly at a 2.66% Ru concentration, outperforming traditional 5 wt% Ru catalysts through superior long-term stability and efficiency.

Operando DRIFT-MS study of oxidative steam reforming of ethanol (OSRE) on Ni-Co mixed oxides under non-equilibrium conditions

The oxidative steam reforming of ethanol (OSRE) reaction to produce hydrogen under non-equilibrium conditions was successfully achieved using mixed oxides (MO) of Ni and Co. The catalysts were synthesized with hydrotalcite (HT) type as a precursor by simultaneous coprecipitation assisted by microwaves. The solids were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), transmission electron microscopy (TEM), N2 adsorption–desorption isotherms, and X-ray photoelectron spectroscopy (XPS). The OSRE reaction was also implemented under operando conditions by diffuse reflectance infrared spectroscopy with Fourier transform coupled to mass spectrometry (DRIFT-MS) to study the path of molecules on the surface of these solids. The results confirmed the presence of the reduced phases of Ni and Co for all the systems and revealed that the OII/OI ratio increased for the samples containing Co, indicating that the greatest number of oxygen vacancies is present in these solids, which explains their high capacity to oxidize CO to CO2 in the catalytic test. It was possible to show that the NiCo bimetallic phase presents better catalytic performance for the production of hydrogen by effectively breaking the C-C bond and oxidizing the CHx species on the surface, which is reflected in the complete conversion of ethanol and a high selectivity to CO2 and H2 over other products such as CO, CH4, and acetaldehyde.

Structural understanding of IrFe catalyst for renewable hydrogen production from ethanol steam reforming

Ethanol steam reforming (ESR) is an attractive way to produce renewable H2 and has been intensely studied. An iron promoted Ir catalyst IrFe/Al2O3 is reported for the first time to show better performance than Ir/Al2O3 in ESR and the structural change in the IrFe/Al2O3 catalyst under realistic ESR conditions is investigated. IrFe alloy is observed after reduction in H2. However, the IrFe alloy is disrupted during ESR because of an adsorption-induced structural change. Ir appears in metallic-like state while Fe exists as partially reduced FexOy under the reaction condition. The active center is therefore IrFexOy instead of IrFe alloy. The discovery of the transformation of IrFe alloy to IrFexOy during ESR deepens the understanding of the dynamic behaviour of IrFe catalyst and provides a correlation between the catalyst structure and catalytic performance.

Cu-promoted Ni-LaCeOx/SBA-15 catalysts for ethanol steam reforming

Hydrogen is a globally recognized high-energy, clean, and ecofriendly fuel that is currently produced by means of electrocatalysis, biomass conversion, coal gasification, and thermal decomposition of hydrocarbons, with the steam reforming showing high potential. The present work is focused on Cu-promoted SBA-15-supported Ni-LaCeOx catalysts for ethanol steam reforming (ESR). The catalysts were prepared by incipient wetness impregnation and characterized by XRF, N2 adsorption-desorption, IR spectroscopy, SAXS, XRD, H2-TPR, Raman, and STA methods. The support features caused by the distribution of LaCeOx NPs and Cu promoter in proper ratios affect the conditions of formation of active dispersed Ni species to determine the catalyst performance and its reducibility. At 800 оС, the NiСu-LaCeOx/SBA-15 (1:1) catalyst demonstrates a 100 % ethanol conversion and 55 % hydrogen yield. Thus, the role of the Cu-containing promoter comprises both a significant decrease of carbon deposits on the catalyst surface and redirecting of the intermediate interactions towards the formation of the desired gaseous products.

The role of various preparation techniques and nickel loadings in ethanol steam reforming over mesoporous nanostructured Ni–Al2O3 catalysts

This study involved the preparation of Al2O3 support and Ni/Al2O3 catalysts through different methods such as mechanochemical, impregnation, and co-precipitation. These prepared samples were then assessed for their performance in the ethanol steam reforming (ESR) process. The results indicated that the 10Ni/Al2O3 catalyst, which was created using the impregnation method and exhibited a high BET surface area of 200.8 m2/g along with well-dispersed nickel, displayed exceptional performance in the ethanol steam reforming reaction. When compared to other catalysts, it exhibited greater activity and stability. A series of Ni/Al2O3 catalysts were prepared with nickel contents ranging from 2.5 to 20 wt%. The study showed that increasing the amount of nickel from 2.5 to 12.5 wt% led to a boost in the catalysts' ability to be reduced, which in turn resulted in improved catalytic performance. However, increasing the nickel content beyond 12.5 wt% led to a decline in catalytic performance. This decrease could be attributed to weaker Ni–Al2O3 interactions, an increase in particle size from 2.7 to 7.8 nm, and a significant reduction in the BET surface area from 198.3 m2/g to 166.4 m2/g. Temperature-programmed oxidation (TPO) profiles revealed that the carbon deposits on the catalyst's surface exhibited a whisker-like structure, and higher nickel contents correlated with increased oxidation peak temperatures and intensities. Moreover, the 12.5Ni/Al2O3 catalyst demonstrated remarkable stability over a 550-min reaction period. The study's findings indicated that as the Tcal. rose from 500 to 700 °C, the catalytic activity gradually lessened. The 12.5Ni/Al2O3 catalyst calcined at 500 °C, characterized by a small particle size and moderate Ni–Al2O3 interaction, exhibited the most favorable catalytic activity.