1,721,359 research outputs found
Aqueous-phase catalytic process for production of pentane from furfural over nickel-based catalysts
No full textSupported nickel catalysts for aqueous-phase catalytic hydrogenation/dehydration of furfural were prepared using impregnation method with different supporting materials. Effects of supporting materials, nickel loading and reaction temperature on conversion rate of furfural as well as selectivity for desired product C(5) were systematically studied. Experiments showed that catalytic activity of Ni/SiO(2)-Al(2)O(3) was obviously higher than that of Ni/gamma-Al(2)O(3). The conversion of furfural over 14 wt.%Ni/SiO(2)-Al(2)O(3) catalyst was 62.99% under the temperature of 140 degrees C and the cold pressure of H(2) 3.0 MPa, while that was 19.19% over 14 wt.%Ni/gamma-Al(2)O(3) under the same conditions. Conversion rate of furfural increased with temperature, but selectivity for desired product decreased with temperature. Tentative reaction mechanisms of hydrogenation/dehydration were proposed. In order to investigate catalyst recyclability, a batch of Ni/SiO(2)-Al(2)O(3) was reused three times and analyzed by Thermogravimetry (TG). It was found that considerable amount of coke formed on Ni/SiO(2)-Al(2)O(3) surface and deteriorated its activity dramatically after second use. (C) 2010 Elsevier Ltd. All rights reserved
Biodiesel production from different feedstocks in pilot scale system
No full textIn this study, the preparations of biodiesel from three different feedstocks, including rapeseed oil, high acidified Chinese wood oil and trap grease, were carried out in a pilot scale of 200 t yr-1 biodiesel production system. The optimum operating conditions for transesterification of rapeseed oil in plug flow reactor were found to be as follows: the catalyst dosage is 1.2 wt%the retention time is about 17 minthe bed temperature is 65oCthe oil/methanol ratio is 1:
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Steam reforming of biomass raw fuel gas over NiO-MgO solid solution cordierite monolith catalyst
No full textThe NiO-MgO solid solution cordierite monolith catalyst was prepared by impregnation. 60 h steam reforming tests were carried out at 1023 K TC was used to analyze the carbon deposition on the catalyst. GC and GC-MS were used to analyze the component of biomass fuel gas and tar. The results show that steam reforming can effectively improve the quality of fuel gas, H(2)/CO ratio can be adjusted by steam reforming, The addition of steam can also increase the activity and stability of the catalyst dramatically. The CH(4) conversion reached 94%. TG shows that the addition of steam can decrease the carbon deposition on the catalyst. GC-MS result shows that most of the tar was converted to H(2), CO and trace lighter component. Steam reforming can eliminate the biomass tar species more deeply than dry reforming. (C) 2009 Elsevier Ltd. All rights reserved
Upgrading of fast pyrolysis liquid fuel from biomass over Ru/gamma-Al2O3 catalyst
No full text
Biomass is one of the important renewable energy. More attention has been paid on conversion of biomass and the upgrading of its products. In this paper, the bio-oil was prepared by pyrolysis of pine sawdust in fast pyrolysis installation. A series of ruthenium catalysts were prepared for the upgrading of bio-oil. The catalytic activity was evaluated by the reaction of the model compound (acetic acid) under 3 MPa hydrogen pressure. The effects of Ru-loading and second metal addition on the catalytic activity were investigated. The 0.5Ru/gamma-Al2O3 catalyst with 0.5%Co addition exhibited the highest activity, giving the highest conversion of acetic acid (30.98%). After upgrading over this catalyst, the properties of the pyrolysis bio-oil were improved. The content of the esters increased by 2-fold in the upgraded oil than in the raw one. The GC-MS spectrometry analysis showed that not only the hydrogenation but also the esterification happened in the bio-oil over the CoRu/gamma-Al2O3 catalyst. Results indicate that it is possible to improve the properties of bio-oil by hydrotreating and esterifying carboxyl groups. (C) 2011 Elsevier Ltd. All rights reserved.</p
A review of thermal-chemical conversion of lignocellulosic biomass in China
No full text
Biomass, a renewable, sustainable and carbon dioxide neutral resource, has received widespread attention in the energy market as an alternative to fossil fuels. Thermal-chemical conversion of biomass to produce biofuels is a promising technology with many commercial applications. This paper reviewed the state-of-the-art research and development of thermal-chemical conversion of biomass in China with a special focus on gasification, pyrolysis, and catalytic transformation technologies. The advantages and disadvantages, potential of future applications, and challenges related to these technologies are discussed. Conclusively, these transformation technologies for the second-generation biofuels with using non-edible lignocellulosic biomass as feedstocks show prosperous perspective for commercial applications in near future. (C) 2012 Elsevier Inc. All rights reserved.</p
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
