Ethanol steam reforming for hydrogen production: Latest and effective catalyst modification strategies to minimize carbonaceous deactivation
TL;DR: In this article, the authors made an attempt to summarize the recent strategies used to reduce the carbonaceous deactivation of catalyst during ESR on the basis of available literature survey, and the role of operating conditions such as water and ethanol feed ratio and temperature with carbon generation were interrelated.
Abstract: Hydrogen is being contemplated as the future fuel in view of the abundant availability of hydrogen bearing substances in nature, its high energy content (120.7 kJ/g), and its combustion without creating any environmental pollution. Pollution free sources for hydrogen generation and efficient conversion to useful energy are the two important factors controlling the development of hydrogen economy. Out of various liquid hydrogen sources, ethanol is a sustainable candidate because of its renewable nature, increasing availability, biodegradable nature, low toxicity, and ease of transport. It can be easily converted to a hydrogen rich mixture through catalytic steam reforming process. Further, ethanol steam reforming (ESR) is thermodynamically feasible and does not cause catalyst poisoning due to complete absence of S-impurities. However, the carbonaceous deposition during ESR is still an issue to make it sustainable for hydrogen generation. This review contains all parallel possible reactions besides the desired reactions, which can promote carbonaceous deposition over catalyst surface with respect to temperature. The role of operating conditions such as water and ethanol feed ratio and temperature with carbon generation were interrelated. The characterization of different carbon forms synthesized during ESR and the possible role of active catalyst into carbon synthesis mechanism was also considered. The contribution of precursor used for catalyst preparation, the role of active metals, the interaction between active metals for bimetallic catalyst, different kind of support prominently studied for ESR and their structural behaviors were also correlated. This review makes an attempt to critically summarize the recent strategies used to reduce the carbonaceous deactivation of catalyst during ESR on the basis of available literature survey. The focus of the review is catalyst deactivation due to carbonaceous deposition during reforming and possible strategies used to control the deactivation process during ESR.
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TL;DR: In this paper, a review of the dark fermentation process utilizing waste materials as substrates is presented, with an emphasis on the most important issues regarding operating parameters of dark fermentation and their effect on the yield.
Abstract: Hydrogen applicability in the power, chemical and petrochemical industries is constantly growing. Efficient methods of hydrogen generation from renewable sources, including waste products, are currently being developed, even though hydrogen is mainly produced through steam reforming or thermal cracking of natural gas or petroleum fractions. In paper alternative methods of hydrogen production with a particular emphasis on dark fermentation are discussed. The review compiles essential information on strains of bacteria used in the production of hydrogen from waste products in the agroindustry and from lignocellulosic biomass. The effect of such parameters as kind of raw material, method of processing, temperature, pH, substrate concentration, partial pressure of hydrogen, hydraulic retention time, method of inoculum preparation and the type and operating parameters of a reactor on the yield of dark fermentation is discussed. The review aims at presentation of current state of knowledge on the dark fermentation process utilizing waste materials as substrates. The results of investigations with emphasis on the most important issues regarding operating parameters of dark fermentation are also included.
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122 citations
TL;DR: In this article, a review summarizes the most recent three years works related to ESR for hydrogen production over non-noble transition metal catalysts, exploring their catalytic performance, coke formation and reaction mechanisms, to provide direction for the development of high-performance catalysts.
114 citations
TL;DR: In this article, a comparative study of Ni catalysts supported on commercially available alumina and lanthana-alumina carriers was undertaken for the glycerol steam reforming reaction (GSR).
90 citations
TL;DR: In this article, different amounts of praseodymium (Pr) were doped into ceria using a sol-gel strategy compared with the traditional impregnation method, and various CeO2 supported Ni catalysts were developed for efficient steam reforming of ethanol.
Abstract: Catalytic steam reforming of ethanol has drawn great attention for sustainable hydrogen production. This paper describes the development of various CeO2 supported Ni catalysts for efficient steam reforming of ethanol. Different amounts of Pr were doped into ceria using a sol-gel strategy compared with the traditional impregnation method. The physicochemical properties of the fresh and spent catalysts, e.g., Ni dispersion, oxygen vacancies, and metal-support interaction, were well characterized by various techniques, including X-ray diffraction, N2 adsorption-desorption, H2 temperature-programmed reduction, H2 chemisorption, Raman, electron paramagnetic resonance, X-ray photoelectron spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Highly dispersed Ni nanoparticles, abundant oxygen vacancies and enhanced metal-support interaction have been achieved by properly doping of praseodymium (Pr) and the sol-gel preparation. The origin of abundant oxygen vacancies in Pr-doped CeO2 supported Ni catalyst has been revealed by density functional theory (DFT) calculations. Active and stable steam reforming of ethanol have been achieved on CeO2 supported Ni with suitable Pr doping. Complete conversion of ethanol has been maintained for more than 7200 min without any activity loss at 600 °C and atmospheric pressure with H2O/C2H5OH of 4 and C2H5OH-H2O gas hourly space velocity (GHSV) of 44,240 ml/gcat h−1 when Ni was loaded on 20%-Pr doped ceria (10Ni-CePr0.20). The rate of coke deposition on the optimal catalyst was as low as 0.00056 gc/gcat·h.
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TL;DR: Iijima et al. as mentioned in this paper reported the preparation of a new type of finite carbon structure consisting of needle-like tubes, which were produced using an arc-discharge evaporation method similar to that used for fullerene synthesis.
Abstract: THE synthesis of molecular carbon structures in the form of C60 and other fullerenes1 has stimulated intense interest in the structures accessible to graphitic carbon sheets. Here I report the preparation of a new type of finite carbon structure consisting of needle-like tubes. Produced using an arc-discharge evaporation method similar to that used for fullerene synthesis, the needles grow at the negative end of the electrode used for the arc discharge. Electron microscopy reveals that each needle comprises coaxial tubes of graphitic sheets, ranging in number from 2 up to about 50. On each tube the carbon-atom hexagons are arranged in a helical fashion about the needle axis. The helical pitch varies from needle to needle and from tube to tube within a single needle. It appears that this helical structure may aid the growth process. The formation of these needles, ranging from a few to a few tens of nanometres in diameter, suggests that engineering of carbon structures should be possible on scales considerably greater than those relevant to the fullerenes. On 7 November 1991, Sumio Iijima announced in Nature the preparation of nanometre-size, needle-like tubes of carbon — now familiar as 'nanotubes'. Used in microelectronic circuitry and microscopy, and as a tool to test quantum mechanics and model biological systems, nanotubes seem to have unlimited potential.
39,086 citations
TL;DR: Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.5.2.
Abstract: 5.1. Nanoalloys of Group 11 (Cu, Ag, Au) 865 5.1.1. Cu−Ag 866 5.1.2. Cu−Au 867 5.1.3. Ag−Au 870 5.1.4. Cu−Ag−Au 872 5.2. Nanoalloys of Group 10 (Ni, Pd, Pt) 872 5.2.1. Ni−Pd 872 * To whom correspondence should be addressed. Phone: +39010 3536214. Fax:+39010 311066. E-mail: ferrando@fisica.unige.it. † Universita di Genova. ‡ Argonne National Laboratory. § University of Birmingham. | As of October 1, 2007, Chemical Sciences and Engineering Division. Volume 108, Number 3
3,114 citations
TL;DR: In this paper, the authors examined various potential methods of hydrogen production using renewable and non-renewable sources and comparatively assessed them for environmental impact, cost, energy efficiency and exergy efficiency.
1,515 citations
TL;DR: A review of the biological and thermochemical methods that could be used to produce bioethanol is made and an analysis of its global production trends is carried out in this paper, where the authors evaluate the utilization of different feedstocks (i.e., sucrose containing, starchy materials, lignocellulosic biomass) is required considering the big share of raw materials in bio-ethanol costs.
1,379 citations
TL;DR: In this paper, the current state of the steam reforming process of ethanol, examines different catalysts, and makes a comparative analysis, and concludes that Co/ZnO, ZnO+Al2O3, Co/CeO2, Ni/La 2O3−Ni/La2O2−Al2E3, and Ni/E3−E2E2−E3 performed the best in terms of steam reforming of ethanol.
Abstract: Hydrogen is considered to be the most viable energy carrier for the future. Producing hydrogen from ethanol steam reforming would not only be environmentally friendly but also would open new opportunities for utilization of renewable resources, which are globally available. This paper reviews the current state of the steam reforming process of ethanol, examines different catalysts, and, finally, makes a comparative analysis. Different catalysts have been used for the steam reforming of ethanol. Depending on the type of catalysts, reaction conditions, and the catalyst preparation method, ethanol conversion and hydrogen production vary greatly. It was observed that Co/ZnO, ZnO, Rh/Al2O3, Rh/CeO2, and Ni/La2O3−Al2O3 performed the best, in regard to the steam reforming of ethanol. Currently, hydrogen production from ethanol steam reforming is still in the research and development stage.
1,255 citations