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Highlights: [•] A char-supported iron catalyst can effectively destroy NO x precursors during biomass gasification. [•] The catalyst speeds up the hydrolysis of HCN to form NH3. [•] At sufficiently long contact time, the catalyst can result in drastic reduction of NH3 to form N2. [Copyright &y& Elsevier]

Adaptive Huffman coding is preferred in communication systems due to its capability in real-time processing. An efficient algorithm for adaptive Huffman coding is presented. The new algorithm utilizes the similarity between the construction processes of the Huffman tree before and after symbol's arrival, and updates much less nodes than Algorithm V to accomplish the code processing. Consequently, the complexity is significantly reduced, the space and time consuming is saved, and hence hardware implementation is greatly simplified. [ABSTRACT FROM AUTHOR]

Three coal macerals with high purities were separated from Pingshuo gas coal. The formation rules of HCN and NH3 during macerals pyrolysis and gasification were investigated. Experiments were carried out in a tubular quartz reactor at atmospheric pressure. The reactor allowed coal particles to be heated up rapidly and held for a prespecified period of time at a peak temperature. The amount of HCN and NH3 were quantified by ion chromatography. The influence of temperature and macerals type on the formation rules of HCN and NH3 was discussed. Results showed that the formation of HCN was mainly due to the thermal cracking of volatile, and NH3 formed both from the thermal cracking of volatile and the cracking of nascent char. The HCN yield increased with an increase in pyrolysis temperature. For three coal macerals (liptinite, vitrinite and inertinite), the yield of HCN depended not only on their volatile contents but also nitrogen-containing functional groups, in which more pyrrole-type nitrogens would form more amount of HCN at lower temperature. The yield of NH3 depended on the ability of forming ‘H’ radical. Under the experiment condition in this study, inertinite could convert more nitrogen into NH3 than vitrinite and liptinite. The yield of HCN during gasification was almost the same as that during pyrolysis, the yield of NH3 during gasification was little higher than that during pyrolysis. [Copyright &y& Elsevier]

Ni/ZrO 2 catalysts with an added second metal were prepared by impregnation method and used in CO 2 methanation. X-ray diffraction, hydrogen temperature programmed reduction, hydrogen temperature programmed desorption, X-ray photoelectron spectroscopy, and in situ infrared spectroscopy measurements were taken to characterize the surface and bulk properties of the catalysts. Compared with Co and Cu, Fe could efficiently enhance the catalytic activity of Ni/ZrO 2 in CO 2 methanation at low temperatures. The optimal amount of Fe was 3 wt.%. CO 2 methanation over Ni–Fe/ZrO 2 catalysts may proceed through dissociation of CO 2 into CO and subsequent reaction of CO with hydrogen to generate methane. Addition of Fe not only can improve the dispersion and degree of reduction of Ni, but also can enhance the partial reduction of zirconia. These effects further promote adsorption and dissociation of H 2 and CO 2 , thus enhancing the activity of the catalyst in CO 2 methanation. [ABSTRACT FROM AUTHOR]

Understanding the conversion of coal-N during gasification is an important part of the development of gasification-based power generation technologies to reduce NO(x) emissions from coal utilization. This study investigated the conversion of coal-N in the presence of NO during the gasification of three rank-ordered coals and their chars in steam and low-concentration O(2). Our results show that NO can be incorporated into the char structure during gasification. The inherent char-N and the N incorporated into the char from NO-char reactions behave very similarly during gasification. During the gasification in steam, significant amounts of HCN and NH(3) can be formed from the incorporated N structure in char, especially for the relatively "aged" chars, mainly due to the availability of abundant H radicals on the char surface during the gasification in steam. During the gasification in 2000 ppm O(2), the formation of HCN or NH(3) from the N structures in char, including those incorporated into the char from the NO-char reactions, was not a favored route of reaction mainly due to the lack of H on char surface in the presence of O(2).