Editorial

2 pages, 150 KiB

Open AccessEditorial

by Hyun-Seog Roh

Catalysts 2021, 11(2), 288; https://doi.org/10.3390/catal11020288 - 22 Feb 2021

Cited by 6 | Viewed by 2311

Rising concerns about the effects of global warming and climate change have led to a search for environmentally clean and energy efficient technologies. Hydrogen is one of the most popular new types of energy, which is considered as a clean energy carrier for [...] Read more.

Rising concerns about the effects of global warming and climate change have led to a search for environmentally clean and energy efficient technologies. Hydrogen is one of the most popular new types of energy, which is considered as a clean energy carrier for the future. Hydrogen is primarily produced by the steam reforming of natural gas. Other methods have also been developed, such as the gasification of coal/biomass/waste, water splitting by electrolysis, and so on. All the ways are using nanocatalysts to obtain a high efficiency of hydrogen production [...] Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

Research

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16 pages, 2356 KiB

Open AccessArticle

The Demonstration of the Superiority of the Dual Ni-Based Catalytic System for the Adjustment of the H₂/CO Ratio in Syngas for Green Fuel Technologies

by Suntorn Sangsong, Tanakorn Ratana, Sabaithip Tungkamani, Thana Sornchamni, Monrudee Phongaksorn and Eric Croiset

Catalysts 2020, 10(9), 1056; https://doi.org/10.3390/catal10091056 - 14 Sep 2020

Cited by 4 | Viewed by 2440

Abstract

A novel dual Ni-based catalytic process (DCP) to control the H₂/CO ratio of 2 in the syngas product within one step at temperature <700 °C was created and constructed. With the sequence of the catalysts located in the single reactor, the [...] Read more.

A novel dual Ni-based catalytic process (DCP) to control the H₂/CO ratio of 2 in the syngas product within one step at temperature <700 °C was created and constructed. With the sequence of the catalysts located in the single reactor, the endothermic combined steam and CO₂ reforming of methane (CSCRM) reaction and the exothermic ultra-high-temperature water–gas shift (UHT-WGS) reaction work continuously. During the process, the H₂/CO ratio is raised suddenly at UHT-WGS after the syngas is produced from CSCRM, and CSCRM utilizes the heat released from UHT-WGS. Due to these features, DCP is more compact, enhances energy efficiency, and thus decreases the capital cost compared to reformers connecting with shift reactors. To prove this propose, the DCP tests were done in a fixed-bed reactor under various conditions (temperature = 500, 550, and 600 °C; the feed mixture (CH₄, CO₂, H₂O, and N₂) with H₂O/(CH₄ + CO₂) ratio = 0.33, 0.53, and 0.67). According to the highest CH₄ conversion (around 65%) with carbon tolerance, the recommended conditions for producing syngas with the H₂/CO ratio of 2 as a feedstock of Fischer–Tropsch synthesis include the temperature of 600 °C and the H₂O/(CH₄ + CO₂) ratio of 0.53. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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16 pages, 4664 KiB

Open AccessArticle

Light Cycle Oil Source for Hydrogen Production through Autothermal Reforming using Ruthenium doped Perovskite Catalysts

by Yukwon Jeon, Hoi-Kyoeng Jung, Cho-I Park, Yonggun Shul and Joo-il Park

Catalysts 2020, 10(9), 1039; https://doi.org/10.3390/catal10091039 - 10 Sep 2020

Cited by 3 | Viewed by 3725

Abstract

As the hydrogen economy is coming soon, the development of an efficient H₂ production system is the first issue to focus on. In this study, a first attempt to utilize light cycle oil (LCO) feedstock is introduced for H₂ production through [...] Read more.

As the hydrogen economy is coming soon, the development of an efficient H₂ production system is the first issue to focus on. In this study, a first attempt to utilize light cycle oil (LCO) feedstock is introduced for H₂ production through autothermal reforming (ATR) using perovskite catalysts. From a careful characterization, it is found that LCO possesses a high content of C–H and S/N compounds with over 3–4 ring bonds. These various compounds can directly cause catalyst deactivations to lower the capability of H₂ extraction from LCO. To achieve a heteroatom resistance, two different perovskite micro-tubular catalysts are designed with a Ru substitution at the B-site. The activity and stability of the Ru doped perovskite were controlled by modifying the Ru electronic structure, which also affects the oxygen structures. The perovskite with a B-site of Cr reveals a relatively high portion of active Ru and O, demonstrating an effective catalyst structure with a comparable LCO reforming activity at the harsh ATR reaction conditions. The greater stability due to the Ru in the perovskite is investigated post-characterization, showing the possibility of H₂ production by LCO fuel through the perovskite catalysts. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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11 pages, 7581 KiB

Open AccessArticle

Beta-Cyclodextrin-Assisted Synthesis of Silver Nanoparticle Network and Its Application in a Hydrogen Generation Reaction

by Clay Huff, Julia M. Long and Tarek M. Abdel-Fattah

Catalysts 2020, 10(9), 1014; https://doi.org/10.3390/catal10091014 - 03 Sep 2020

Cited by 21 | Viewed by 3280

Abstract

The unsustainable nature of carbon-based fuels has prompted scientists and engineers to investigate alternative sources of energy. Silver nanoparticle networks (AgNPNs) were synthesized using beta-cyclodextrin for applications in hydrogen evolution reactions from sodium borohydride (NaBH₄). The identities of the AgNPNs were [...] Read more.

The unsustainable nature of carbon-based fuels has prompted scientists and engineers to investigate alternative sources of energy. Silver nanoparticle networks (AgNPNs) were synthesized using beta-cyclodextrin for applications in hydrogen evolution reactions from sodium borohydride (NaBH₄). The identities of the AgNPNs were confirmed using ultraviolet–visible spectroscopy, X-ray diffraction, and Transmission electron microscopy (TEM). The catalytic activity of the hydrogen evolution reactions was measured using a gravimetric water displacement system. The data collected show an increase in the efficiency of the hydrogen generation reaction with the addition of AgNPN. The silver nanoparticle network catalyst performed best at 22 °C with an increased concentration of NaBH₄ producing hydrogen at a rate of 0.961 mL∙min⁻¹∙mL_cat⁻¹. The activation energy was calculated to be 50.3 kJ/mol. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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16 pages, 6664 KiB

Open AccessArticle

Regeneration of Pt-Sn/Al₂O₃ Catalyst for Hydrogen Production through Propane Dehydrogenation Using Hydrochloric Acid

by Yi Sun Choi, Kyeongseok Oh, Kwang-Deog Jung, Won-Il Kim and Hyoung Lim Koh

Catalysts 2020, 10(8), 898; https://doi.org/10.3390/catal10080898 - 07 Aug 2020

Cited by 12 | Viewed by 5018

Abstract

Compared with dehydrogenation in conventional petroleum refinery processes, relatively pure hydrogen can be produced by propane dehydrogenation (PDH) without innate contaminants like sulfur and metals. Among the existing catalysts for PDH, Pt catalysts are popular and are often used in conjunction with Sn [...] Read more.

Compared with dehydrogenation in conventional petroleum refinery processes, relatively pure hydrogen can be produced by propane dehydrogenation (PDH) without innate contaminants like sulfur and metals. Among the existing catalysts for PDH, Pt catalysts are popular and are often used in conjunction with Sn as a co-catalyst. Coke formation is a major concern in PDH, where catalyst regeneration is typically achieved by periodic coke burning to achieve sustainable operation. In this study, Pt-Sn/Al₂O₃ catalysts were regenerated after coke burning in three stages: mixing the catalyst with liquid hydrochloric acid, drying, and calcining under air atmosphere. In this process, the optimum concentration of hydrochloric acid was found to be 35% w/w. HCl treatment was effective for enhancing redispersion of the metal catalysts and aiding the formation of the Pt₃Sn alloy, which is considered to be effective for PDH reaction. HCl treatment may provide oxychlorination-like conditions under the calcination atmosphere. The characteristics of the catalysts were examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS), and CO chemisorption. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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14 pages, 5006 KiB

Open AccessArticle

Effect of Mg Contents on Catalytic Activity and Coke Formation of Mesoporous Ni/Mg-Aluminate Spinel Catalyst for Steam Methane Reforming

by Hyunjoung Kim, Young-Hee Lee, Hongjin Lee, Jeong-Cheol Seo and Kyubock Lee

Catalysts 2020, 10(8), 828; https://doi.org/10.3390/catal10080828 - 23 Jul 2020

Cited by 12 | Viewed by 3330

Abstract

Ni catalysts are most suitable for a steam methane reforming (SMR) reaction considering the activity and the cost, although coke formation remains the main problem. Here, Ni-based spinel catalysts with various Mg contents were developed through the synthesis of mesoporous Mg-aluminate supports by [...] Read more.

Ni catalysts are most suitable for a steam methane reforming (SMR) reaction considering the activity and the cost, although coke formation remains the main problem. Here, Ni-based spinel catalysts with various Mg contents were developed through the synthesis of mesoporous Mg-aluminate supports by evaporation-induced self-assembly followed by Ni loading via incipient wetness impregnation. The mesoporous Ni/Mg-aluminate spinel catalysts showed high coke resistance under accelerated reaction conditions (0.0014 g_coke/g_cat·h for Ni/Mg30, 0.0050 g_coke/g_cat·h for a commercial catalyst). The coke resistance of the developed catalyst showed a clear trend: the higher the Mg content, the lower the coke deposition. The Ni catalysts with the lower Mg content showed a higher surface area and smaller Ni particle size, which originated from the difference of the sintering resistance and the exsolution of Ni particles. Despite these advantageous attributes of Ni catalysts, the coke resistance was higher for the catalysts with the higher Mg content while the catalytic activity was dependent on the reaction conditions. This reveals that the enhanced basicity of the catalyst could be the major parameter for the reduction of coke deposition in the SMR reaction. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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13 pages, 2277 KiB

Open AccessArticle

Enhanced CO₂ Methanation Reaction in C1 Chemistry over a Highly Dispersed Nickel Nanocatalyst Prepared Using the One-Step Melt-Infiltration Method

by Eui Hyun Cho, Woohyun Kim, Chang Hyun Ko and Wang Lai Yoon

Catalysts 2020, 10(6), 643; https://doi.org/10.3390/catal10060643 - 08 Jun 2020

Cited by 7 | Viewed by 2701

Abstract

The Paris Agreement requires the world to put the best efforts to reduce CO₂ emissions, due to the global warming problems. As a promising technology corresponding to this greenhouse gas treatment, the CO₂ methanation process a.k.a power to gas (PtoG), which [...] Read more.

The Paris Agreement requires the world to put the best efforts to reduce CO₂ emissions, due to the global warming problems. As a promising technology corresponding to this greenhouse gas treatment, the CO₂ methanation process a.k.a power to gas (PtoG), which catalytically converts CO₂ into methane, has been in the limelight. To develop an efficient catalytic process, it is necessary to design a low-cost and high-efficiency catalyst for high CO₂ conversion and CH₄ selectivity. In this study, we have developed Ni/γ-Al₂O₃ catalysts by the one-step melt-infiltration method, where both aging and calcination are done in one pot. For enhancement of the catalytic activity and selectivity, sufficient Ni content (>25 wt %) and a high dispersion (<10 nm) are simultaneously required. Thus, the aging conditions of the melt-infiltration methods, e.g., time and temperature, were optimized for the high dispersion with sufficient Ni content (15–50 wt %). The catalytic performance tests were carried out under atmospheric pressure, 275 to 400 °C and gas hourly velocity (GHSV) = 25,000 h⁻¹. And the various characteristic analyses (Brunauer–Emmett–Teller (BET), X-ray diffraction (XRD), H₂-chemisorption, temperature programmed reduction (TPR), etc.) were performed to confirm the effects on the catalytic performance. As a result, based on the experiments and the characterization data, the 30 wt %-Ni catalyst (Ni particles size = 11 nm) showed the best CO₂ conversion at 300 °C and the 20 wt % one having the highest Ni dispersion (Ni particles size = 8.8 nm), which showed the best intrinsic reaction rate and CH₄ selectivity in the entire temperature range. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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14 pages, 2011 KiB

Open AccessArticle

Efficient Waste to Energy Conversion Based on Co-CeO₂ Catalyzed Water-Gas Shift Reaction

by Kyoung-Jin Kim, Yeol-Lim Lee, Hyun-Suk Na, Seon-Yong Ahn, Jae-Oh Shim, Byong-Hun Jeon and Hyun-Seog Roh

Catalysts 2020, 10(4), 420; https://doi.org/10.3390/catal10040420 - 12 Apr 2020

Cited by 25 | Viewed by 3433

Abstract

Waste to energy technology is attracting attention to overcome the upcoming environmental and energy issues. One of the key-steps is the water-gas shift (WGS) reaction, which can convert the waste-derived synthesis gas (H₂ and CO) to pure hydrogen. Co–CeO₂ catalysts were [...] Read more.

Waste to energy technology is attracting attention to overcome the upcoming environmental and energy issues. One of the key-steps is the water-gas shift (WGS) reaction, which can convert the waste-derived synthesis gas (H₂ and CO) to pure hydrogen. Co–CeO₂ catalysts were synthesized by the different methods to derive the optimal synthetic method and to investigate the effect of the preparation method on the physicochemical characteristics of Co–CeO₂ catalysts in the high-temperature water-gas shift (HTS) reaction. The Co–CeO₂ catalyst synthesized by the sol-gel method featured a strong metal to support interaction and the largest number of oxygen vacancies compared to other catalysts, which affects the catalytic activity. As a result, the Co–CeO₂ catalyst synthesized by the sol-gel method exhibited the highest WGS activity among the prepared catalysts, even in severe conditions (high CO concentration: ~38% in dry basis and high gas hourly space velocity: 143,000 h⁻¹). Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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17 pages, 3970 KiB

Open AccessArticle

Numerical Simulation and Experimental Study on Commercial Diesel Reforming Over an Advanced Pt/Rh Three-Way Catalyst

by Hanyu Chen, Xi Wang, Zhixiang Pan and Hongming Xu

Catalysts 2019, 9(7), 590; https://doi.org/10.3390/catal9070590 - 07 Jul 2019

Cited by 6 | Viewed by 3056

Abstract

Hydrocarbon fuel reforming has been proven useful for producing hydrogen that is utilized on road vehicles, but it is associated with reaction mechanism and catalyst characterization. In this study, a reduced mechanism for n-heptane/toluene reforming over an advanced Pt/Rh TWC is adopted [...] Read more.

Hydrocarbon fuel reforming has been proven useful for producing hydrogen that is utilized on road vehicles, but it is associated with reaction mechanism and catalyst characterization. In this study, a reduced mechanism for n-heptane/toluene reforming over an advanced Pt/Rh TWC is adopted to investigate the effects of the reaction conditions on H₂ and CO concentrations. The physical and chemical properties of the advanced catalyst are examined using SEM, XRD and XPS analyses. The contrasted experiments are conducted to study the composition variation tendency of the reforming reactor gas product. The results show that the POX reaction is most likely to occur considering the stoichiometric ratio of H₂/CO, and other reactions are SR or ATR. The coke formation and carbon deposition occur on the catalyst surface, and the diffraction peaks corresponding to the metallic Pt are observed, while no obvious peaks characteristic of Rh are detected. The characteristics of the concentration trend of n-heptane/toluene reforming can represent H₂ and CO yield features of diesel reforming in a way; nevertheless, the difference of the average H₂ and CO concentration is remarkable. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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Review

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18 pages, 5168 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Catalytic Hydrogen Production from Methane: A Review on Recent Progress and Prospect

by Luning Chen, Zhiyuan Qi, Shuchen Zhang, Ji Su and Gabor A. Somorjai

Catalysts 2020, 10(8), 858; https://doi.org/10.3390/catal10080858 - 02 Aug 2020

Cited by 188 | Viewed by 17606

Abstract

Natural gas (Methane) is currently the primary source of catalytic hydrogen production, accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However, the SMR process [...] Read more.

Natural gas (Methane) is currently the primary source of catalytic hydrogen production, accounting for three quarters of the annual global dedicated hydrogen production (about 70 M tons). Steam–methane reforming (SMR) is the currently used industrial process for hydrogen production. However, the SMR process suffers with insufficient catalytic activity, low long-term stability, and excessive energy input, mostly due to the handling of large amount of CO₂ coproduced. With the demand for anticipated hydrogen production to reach 122.5 M tons in 2024, novel and upgraded catalytic processes are desired for more effective utilization of precious natural resources. In this review, we summarized the major descriptors of catalyst and reaction engineering of the SMR process and compared the SMR process with its derivative technologies, such as dry reforming with CO₂ (DRM), partial oxidation with O₂, autothermal reforming with H₂O and O₂. Finally, we discussed the new progresses of methane conversion: direct decomposition to hydrogen and solid carbon and selective oxidation in mild conditions to hydrogen containing liquid organics (i.e., methanol, formic acid, and acetic acid), which serve as alternative hydrogen carriers. We hope this review will help to achieve a whole picture of catalytic hydrogen production from methane. Full article

(This article belongs to the Special Issue Nanocatalysts for Hydrogen Production)

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