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Fluidized bed biomass gasifiers can be employed to produce hydrogen-rich gas. A non-premixed combustion model is used for biomass air-steam gasification in the gasifier, and the simulations were carried out by using the FLUENT 6.0 software. The simulation results are compared with the experimental data. The effects of the steam to biomass ratio (S/B), the equivalence ratio (ER), and the size of biomass particles on the hydrogen yield were studied. Meanwhile, the distributions of hydrogen inside the gasifier at different conditions are also described. 相似文献
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辅酶NAD(P)H在生物氧化还原反应中起着重要作用[1].1-苄基-1,4-二氢尼古丁酰胺(BNAH)作为其模型物,被广泛用于物理有机和生物化学的研究之中[2].虽然绝大多数的研究都集中于还原反应机理方面[3,4],BNAH作为还原剂在有机合成中的应用也是值得注意的.我们曾用BNAH还原2-溴-1-苯亚乙基丙二腈及其类似物合成取代环丙烷[5~7],方法简便.五元环结构广泛存在于萜类和甾体等天然产物中.对于茚等苯并五元环结构的合成已有许多方法[8~11]. 其中,2,2-双取代1,2-二氢茚(1)(吸电子取代基)是用邻-二溴甲基苯与丙二腈等活泼亚甲基化合物在DMSO中,NaH存在下双分子缩合制备的[12]. 相似文献
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It is demonstrated that in all types of hydrogen bonds (X—H…Y) there is a balance between the long-range attractive orbital interactions and short-range Pauli/nucleus repulsions. When the proton acceptor approaches the proton donor from distance, the hydrogen bonding energy becomes more negative at relatively large distance, goes through a minimum, and then starts to become less negative when the short-range repulsive forces come into effect.Meanwhile, the X--H bond length increases at relatively large distances, goes through a maximum and starts to shorten when the short-range repulsive forces come into effect. Whether the hydrogen bond is red or blue shifted is dictated by the energy minimum position. If at the energy minimum position the X—H bond length is shorter than that for the free monomer, the hydrogen bond is blue shifted and vice versa. Further studies demonstrate that the recent report about the correlation of C—H bond lengths with proton donor-acceptor distance in F3C—H…OH2 and F3C—H…Cl^- is not fully correct because the authors conducted an inappropriate comparison. Furthermore, it is shown for the first time that the Pauli/nucleus repulsion theory is applicable to the blue-shifted hydrogen bonds in the X—H…π complexes and the blue-shifted lithium bonds in the X—Li…Y complexes. 相似文献
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采用脉冲辐解瞬态吸收光谱法研究了水溶液中水合电子引发cis-syn型1, 3-二甲基尿嘧啶环丁烷型二聚体(DMUD)裂解、生成嘧啶单体和嘧啶阴离子自由基, 以及在核黄素(RF)和黄素腺嘌呤二核苷酸(FAD)存在下, 尿嘧啶阴离子自由基和RF及FAD之间的电子转移反应过程, 测定了电子转移反应的速率常数. 当没有RF或FAD作为电子受体时, 尿嘧啶阴离子自由基可能继续和DMUD反应, 以链反应形式进行. 相似文献
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Theoretical Study of Remote Substituent Effects on X-H (X=CH2, NH,O) Bond Dissociation Energies of Azulene 总被引:1,自引:0,他引:1
In the study, the X-H (X=CH2, NH, O) bond dissociation energies (BDE) of para-substituted azulene (Y-C10H8X-H) were predicted theoretically for the first time using Density Functronal Theory (DFT) methods at UB3LYP/6-311 + +g(2df,2p)//UB3LYP/6-31 +g(d) level. It was found that the substituents exerted similar effects on the X-H BDE of azulene as those on benzene, except for 6-substituted 2-methylazulene. Owing to the substituent-dipole interaction, the reaction constants (ρ^+) of 2- and 6-Y-CIoHsX-H (X=NH and O only) varied violently. The origin of the substituent effects on the X-H BDE of azulene was found, by both GE/RE and SIE theory, to be directly associated with variation of the radical effects, although the ground effects also played a modest role in determining the net. substituent effects. 相似文献