Special Issue "Catalysts for Syngas Production"

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Environmental Catalysis".

Deadline for manuscript submissions: closed (31 May 2019).

Special Issue Editor

Dr. Javier Ereña
E-Mail Website
Guest Editor
Department of Chemical Engineering, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain
Interests: Catalysis; CO2 transformation; Fuels and Chemicals from CO2; Syngas
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Synthesis gas (or syngas) is a mixture of hydrogen and carbon monoxide, with different chemical composition and H2/CO molar ratios, depending on the feedstock and production technology used. Syngas may be obtained from alternative sources to oil, such as natural gas, coal, biomass, organic wastes, etc. Syngas is a very good intermediate for the production of high value compounds at the industrial scale, such as hydrogen, methanol, liquid fuels, and a wide range of chemicals. Accordingly, efforts should be made on the co-feeding of CO2 with syngas, as an alternative for reducing greenhouse gas emissions. In addition, more syngas will be required in the near future in order to satisfy the demand for synfuels and high value chemicals.

New research for syngas production is essential for reducing operating costs, improving the thermal efficiency of the process, and preserving the environment. Advances should be made on the following aspects:

  • Development of new catalysts and catalytic routes for syngas production.
  • Optimization of the reaction conditions for the process.
  • Use of biomass, as a promising raw material for syngas production due to its renewable character and potentially zero CO2 emission 
  • Steps further on catalytic processes for saving energy and capital cost, and for optimizing the quality and properties of syngas, such as H2/CO molar ratio and absence of contaminants.

Dr. Javier Ereña
Guest Editor

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Keywords

  • Catalytic processes for synthesis gas production
  • Syngas
  • Hydrogen
  • CO2
  • Water gas shift reaction
  • Natural gas
  • Coal
  • Biomass
  • Reforming
  • Partial oxidation
  • Gasification

Published Papers (9 papers)

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Research

Open AccessArticle
Methane and Ethane Steam Reforming over MgAl2O4-Supported Rh and Ir Catalysts: Catalytic Implications for Natural Gas Reforming Application
Catalysts 2019, 9(10), 801; https://doi.org/10.3390/catal9100801 - 25 Sep 2019
Abstract
Solar concentrators employed in conjunction with highly efficient micro- and meso-channel reactors offer the potential for cost-effective upgrading of the energy content of natural gas, providing a near-term path towards a future solar-fuel economy with reduced carbon dioxide emissions. To fully exploit the [...] Read more.
Solar concentrators employed in conjunction with highly efficient micro- and meso-channel reactors offer the potential for cost-effective upgrading of the energy content of natural gas, providing a near-term path towards a future solar-fuel economy with reduced carbon dioxide emissions. To fully exploit the heat and mass transfer advantages offered by micro- and meso-channel reactors, highly active and stable natural gas steam reforming catalysts are required. In this paper, we report the catalytic performance of MgAl2O4-supported Rh (5 wt.%), Ir (5 wt.%), and Ni (15 wt.%) catalysts used for steam reforming of natural gas. Both Rh- and Ir-based catalysts are known to be more active and durable than conventional Ni-based formulations, and recently Ir has been reported to be more active than Rh for methane steam reforming on a turnover basis. Thus, the effectiveness of all three metals to perform natural gas steam reforming was evaluated in this study. Here, the Rh- and Ir-supported catalysts both exhibited higher activity than Ni for steam methane reforming. However, using simulated natural gas feedstock (94.5% methane, 4.0% ethane, 1.0% propane, and 0.5% butane), the Ir catalyst was the least active (on a turnover basis) for steam reforming of higher hydrocarbons (C2+) contained in the feedstock when operated at <750 °C. To further investigate the role of higher hydrocarbons, we used an ethane feed and found that hydrogenolysis precedes the steam reforming reaction and that C–C bond scission over Ir is kinetically slow compared to Rh. Catalyst durability studies revealed the Rh catalyst to be stable under steam methane reforming conditions, as evidenced by two 100-hour duration experiments performed at 850 and 900 °C (steam to carbon [S/C] molar feed ratio = 2.0 mol). However, with the natural gas simulant feed, the Rh catalyst exhibited catalyst deactivation, which we attribute to coking deposits derived from higher hydrocarbons contained in the feedstock. Increasing the S/C molar feed ratio from 1.5 to 2.0 reduced the deactivation rate and stable catalytic performance was demonstrated for 120 h when operated at 850 °C. However, catalytic deactivation was observed when operating at 900 °C. While improvements in steam reforming performance can be achieved through choice of catalyst composition, this study also highlights the importance of considering the effect of higher hydrocarbons contained in natural gas, operating conditions (e.g., temperature, S/C feed ratio), and their effect on catalyst stability. The results of this study conclude that a Rh-supported catalyst was developed that enables very high activities and excellent catalytic stability for both the steam reforming of methane and other higher hydrocarbons contained in natural gas, and under conditions of operation that are amendable to solar thermochemical operations. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Highly Active Catalysts Based on the Rh4(CO)12 Cluster Supported on Ce0.5Zr0.5 and Zr Oxides for Low-Temperature Methane Steam Reforming
Catalysts 2019, 9(10), 800; https://doi.org/10.3390/catal9100800 - 25 Sep 2019
Abstract
Syngas and Hydrogen productions from methane are industrially carried out at high temperatures (900 °C). Nevertheless, low-temperature steam reforming can be an alternative for small-scale plants. In these conditions, the process can also be coupled with systems that increase the overall efficiency such [...] Read more.
Syngas and Hydrogen productions from methane are industrially carried out at high temperatures (900 °C). Nevertheless, low-temperature steam reforming can be an alternative for small-scale plants. In these conditions, the process can also be coupled with systems that increase the overall efficiency such as hydrogen purification with membranes, microreactors or enhanced reforming with CO2 capture. However, at low temperature, in order to get conversion values close to the equilibrium ones, very active catalysts are needed. For this purpose, the Rh4(CO)12 cluster was synthetized and deposited over Ce0.5Zr0.5O2 and ZrO2 supports, prepared by microemulsion, and tested in low-temperature steam methane reforming reactions under different conditions. The catalysts were active at 750 °C at low Rh loadings (0.05%) and outperformed an analogous Rh-impregnated catalyst. At higher Rh concentrations (0.6%), the Rh cluster deposited on Ce0.5Zr0.5 oxide reached conversions close to the equilibrium values and good stability over long reaction time, demonstrating that active phases derived from Rh carbonyl clusters can be used to catalyze steam reforming reactions. Conversely, the same catalyst suffered from a fast deactivation at 500 °C, likely related to the oxidation of the Rh phase due to the oxygen-mobility properties of Ce. Indeed, at 500 °C the Rh-based ZrO2-supported catalyst was able to provide stable results with higher conversions. The effects of different pretreatments were also investigated: at 500 °C, the catalysts subjected to thermal treatment, both under N2 and H2, proved to be more active than those without the H2 treatment. In general, this work highlights the possibility of using Rh carbonyl-cluster-derived supported catalysts in methane reforming reactions and, at low temperature, it showed deactivation phenomena related to the presence of reducible supports. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Recent Advances in Industrial Sulfur Tolerant Water Gas Shift Catalysts for Syngas Hydrogen Enrichment: Application of Lean (Low) Steam/Gas Ratio
Catalysts 2019, 9(9), 772; https://doi.org/10.3390/catal9090772 - 14 Sep 2019
Abstract
A novel sulfur tolerant water gas shift (SWGS) catalyst has been developed for the applications under lean (low) steam/gas ratio conditions, which has been extensively used for H2/CO adjustment of syngas and H2 enrichment in the world since 2000s with [...] Read more.
A novel sulfur tolerant water gas shift (SWGS) catalyst has been developed for the applications under lean (low) steam/gas ratio conditions, which has been extensively used for H2/CO adjustment of syngas and H2 enrichment in the world since 2000s with safer operation and lower steam consumption. Technology design and catalyst performances under different lean steam/gas conditions were comprehensively reported. Industrial data were collected from several large scale running plants with a variety of served catalysts characterized and precisely re-examined in the laboratory. It is shown that the developed Mo–Co/alkali/Al2O3 SWGS catalyst can operate very steadily even with the steam/gas ratio as low as 0.2–0.3, and the main deactivation factors are accidental caking, sintering, as well as poisoning impurities, such as As or Cl. The adoption of lean steam/gas SWGS catalyst can significantly improve the plant efficiency & safety and remarkably reduce the actual steam consumption for H2 production, which can decrease CO2 emission correspondingly. The work helps to evaluate how specially designed SWGS catalysts performed under applied lean steam/gas conditions, providing important references for researchers and industry. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Bench-Scale Steam Reforming of Methane for Hydrogen Production
Catalysts 2019, 9(7), 615; https://doi.org/10.3390/catal9070615 - 20 Jul 2019
Abstract
The effects of reaction parameters, including reaction temperature and space velocity, on hydrogen production via steam reforming of methane (SRM) were investigated using lab- and bench-scale reactors to identify critical factors for the design of large-scale processes. Based on thermodynamic and kinetic data [...] Read more.
The effects of reaction parameters, including reaction temperature and space velocity, on hydrogen production via steam reforming of methane (SRM) were investigated using lab- and bench-scale reactors to identify critical factors for the design of large-scale processes. Based on thermodynamic and kinetic data obtained using the lab-scale reactor, a series of SRM reactions were performed using a pelletized catalyst in the bench-scale reactor with a hydrogen production capacity of 10 L/min. Various temperature profiles were tested for the bench-scale reactor, which was surrounded by three successive cylindrical furnaces to simulate the actual SRM conditions. The temperature at the reactor bottom was crucial for determining the methane conversion and hydrogen production rates when a sufficiently high reaction temperature was maintained (>800 °C) to reach thermodynamic equilibrium at the gas-hourly space velocity of 2.0 L CH4/(h·gcat). However, if the temperature of one or more of the furnaces decreased below 700 °C, the reaction was not equilibrated at the given space velocity. The effectiveness factor (0.143) of the pelletized catalyst was calculated based on the deviation of methane conversion between the lab- and bench-scale reactions at various space velocities. Finally, an idling procedure was proposed so that catalytic activity was not affected by discontinuous operation. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Ni-Mo Sulfide Semiconductor Catalyst with High Catalytic Activity for One-Step Conversion of CO2 and H2S to Syngas in Non-Thermal Plasma
Catalysts 2019, 9(6), 525; https://doi.org/10.3390/catal9060525 - 12 Jun 2019
Abstract
Carbon dioxide (CO2) and hydrogen sulfide (H2S) ordinarily coexist in many industries, being considered as harmful waste gases. Simultaneously converting CO2 and H2S into syngas (a mixture of CO and H2) will be a [...] Read more.
Carbon dioxide (CO2) and hydrogen sulfide (H2S) ordinarily coexist in many industries, being considered as harmful waste gases. Simultaneously converting CO2 and H2S into syngas (a mixture of CO and H2) will be a promising economic strategy for enhancing their recycling value. Herein, a novel one-step conversion of CO2 and H2S to syngas induced by non-thermal plasma with the aid of Ni-Mo sulfide/Al2O3 catalyst under ambient conditions was designed. The as-synthesized catalysts were characterized by using XRD, nitrogen sorption, UV-vis, TEM, SEM, ICP, and XPS techniques. Ni-Mo sulfide/Al2O3 catalysts with various Ni/Mo molar ratios possessed significantly improved catalytic performances, compared to the single-component catalysts. Based on the modifications of the physical and chemical properties of the Ni-Mo sulfide/Al2O3 catalysts, the variations in catalytic activity are carefully discussed. In particular, among all the catalysts, the 5Ni-3Mo/Al2O3 catalyst exhibited the best catalytic behavior with high CO2 and H2S conversion at reasonably low-energy input in non-thermal plasma. This method provides an alternative route for syngas production with added environmental and economic benefits. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Combined Magnesia, Ceria and Nickel catalyst supported over γ-Alumina Doped with Titania for Dry Reforming of Methane
Catalysts 2019, 9(2), 188; https://doi.org/10.3390/catal9020188 - 18 Feb 2019
Cited by 2
Abstract
This study investigated dry reforming of methane (DRM) over combined catalysts supported on γ-Al2O3 support doped with 3.0 wt. % TiO2. Physicochemical properties of all catalysts were determined by inductively coupled plasma/mass spectrometry (ICP-MS), nitrogen physisorption, X-ray diffraction, [...] Read more.
This study investigated dry reforming of methane (DRM) over combined catalysts supported on γ-Al2O3 support doped with 3.0 wt. % TiO2. Physicochemical properties of all catalysts were determined by inductively coupled plasma/mass spectrometry (ICP-MS), nitrogen physisorption, X-ray diffraction, temperature programmed reduction/oxidation/desorption/pulse hydrogen chemisorption, thermogravimetric analysis, and scanning electron microscopy. Addition of CeO2 and MgO to Ni strengthened the interaction between the Ni and the support. The catalytic activity results indicate that the addition of CeO2 and MgO to Ni did not reduce carbon deposition, but improved the activity of the catalysts. Temperature programmed oxidation (TPO) revealed the formation of carbon that is mainly amorphous and small amount of graphite. The highest CH4 and CO2 conversion was found for the catalyst composed of 5.0 wt. % NiO-10.0 wt. % CeO2/3.0 wt. %TiO2-γ-Al2O3 (Ti-CAT-II), resulting in H2/CO mole ratio close to unity. The optimum reaction conditions in terms of reactant conversion and H2/CO mole ratio were achieved by varying space velocity and CO2/CH4 mole ratio. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
A Facile Fabrication of Supported Ni/SiO2 Catalysts for Dry Reforming of Methane with Remarkably Enhanced Catalytic Performance
Catalysts 2019, 9(2), 183; https://doi.org/10.3390/catal9020183 - 15 Feb 2019
Cited by 3
Abstract
Ni catalysts supported on SiO2 are prepared via a facile combustion method. Both glycine fuel and ammonium nitrate combustion improver facilitate the formation of much smaller Ni nanoparticles, which give excellent activity and stability, as well as a syngas with a molar [...] Read more.
Ni catalysts supported on SiO2 are prepared via a facile combustion method. Both glycine fuel and ammonium nitrate combustion improver facilitate the formation of much smaller Ni nanoparticles, which give excellent activity and stability, as well as a syngas with a molar ratio of H2/CO of about 1:1 due to the minimal side reaction toward revserse water gas shift (RWGS) in CH4 dry reforming. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
In Situ Regeneration of Alumina-Supported Cobalt–Iron Catalysts for Hydrogen Production by Catalytic Methane Decomposition
Catalysts 2018, 8(11), 567; https://doi.org/10.3390/catal8110567 - 21 Nov 2018
Cited by 1
Abstract
A novel approach to the in situ regeneration of a spent alumina-supported cobalt–iron catalyst for catalytic methane decomposition is reported in this work. The spent catalyst was obtained after testing fresh catalyst in catalytic methane decomposition reaction during 90 min. The regeneration evaluated [...] Read more.
A novel approach to the in situ regeneration of a spent alumina-supported cobalt–iron catalyst for catalytic methane decomposition is reported in this work. The spent catalyst was obtained after testing fresh catalyst in catalytic methane decomposition reaction during 90 min. The regeneration evaluated the effect of forced periodic cycling; the cycles of regeneration were performed in situ at 700 °C under diluted O2 gasifying agent (10% O2/N2), followed by inert treatment under N2. The obtained regenerated catalysts at different cycles were tested again in catalytic methane decomposition reaction. Fresh, spent, and spent/regenerated materials were characterized using X-ray powder diffraction (XRD), transmission electron microscopy (TEM), laser Raman spectroscopy (LRS), N2-physisorption, H2-temperature programmed reduction (H2-TPR), thermogravimetric analysis (TGA), and atomic absorption spectroscopy (AAS). The comparison of transmission electron microscope and X-ray powder diffraction characterizations of spent and spent/regenerated catalysts showed the formation of a significant amount of carbon on the surface with a densification of catalyst particles after each catalytic methane decomposition reaction preceded by regeneration. The activity results confirm that the methane decomposition after regeneration cycles leads to a permanent deactivation of catalysts certainly provoked by the coke deposition. Indeed, it is likely that some active iron sites cannot be regenerated totally despite the forced periodic cycling. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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Open AccessArticle
Catalytic Performance and Characterization of Ni-Co Bi-Metallic Catalysts in n-Decane Steam Reforming: Effects of Co Addition
Catalysts 2018, 8(11), 518; https://doi.org/10.3390/catal8110518 - 05 Nov 2018
Abstract
Co-Ni bi-metallic catalysts supported on Ce-Al2O3 (CA) were prepared with different Co ratios, and the catalytic behaviors were assessed in the n-decane steam reforming reaction with the purpose of obtaining high H2 yield with lower inactivation by carbon [...] Read more.
Co-Ni bi-metallic catalysts supported on Ce-Al2O3 (CA) were prepared with different Co ratios, and the catalytic behaviors were assessed in the n-decane steam reforming reaction with the purpose of obtaining high H2 yield with lower inactivation by carbon deposition. Physicochemical characteristics studies, involving N2 adsorption-desorption, X-ray diffraction (XRD), H2-temperature-programmed reduction (H2-TPR), NH3-temperature-programmed desorption (NH3-TPD), SEM-energy dispersive spectrometer (EDS), and transmission electron microscope (TEM)/HRTEM, were performed to reveal the textural, structural and morphological properties of the catalysts. Activity test indicated that the addition of moderate Co can improve the hydrogen selectivity and anti-coking ability compared with the mono-Ni/Ce-Al2O3 contrast catalyst. In addition, 12% Co showed the best catalytic activity in the series Co-Ni/Ce-Al2O3 catalysts. The results of catalysts characterizations of XRD and N2 adsorption-desorption manifesting the metal-support interactions were significantly enhanced, and there was obvious synergistic effect between Ni and Co. Moreover, the introduction of 12% Co and 6% Ni did not exceed the monolayer saturation capacity of the Ce-Al2O3 support. Finally, 6 h stability test for the optimal catalyst 12%Co-Ni/Ce-Al2O3 demonstrated that the catalyst has good long-term stability to provide high hydrogen selectivity, as well as good resistance to coke deposition. Full article
(This article belongs to the Special Issue Catalysts for Syngas Production)
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