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231.
生物质催化气化制氢技术研究 总被引:1,自引:0,他引:1
在人类面临严重的能源危机与环境污染的背景下,世界各国都在致力于对洁净能源氢的开发和研究,并取得了一定的研究成果。生物质气化制氢是一项富有前景的制氢技术,已引起了世界各国研究者的普遍关注。文章首先介绍了生物质气化制氢技术的国内外研究及应用现状,然后介绍了一种一体式生物质气化炉水蒸汽催化气化制氢的工艺流程,氢气体积的含量可达到50%以上。最后总结了这种工艺在各种制氢方法中,具有技术成熟、工艺简单,效率高等优点,有广阔的应用前景。 相似文献
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《环境科学学报(英文版)》2023,35(2):491-504
Ce1-xZrxO2 composite oxides (molar, x = 0-1.0, interval of 0.2) were prepared by a cetyltrimethylammonium bromide-assisted precipitation method. The enhancement of silver-species modification and catalytic mechanism of adsorption-transformation-desorption process were investigated over the Ag-impregnated catalysts for low-temperature selective catalytic oxidation of ammonia (NH3-SCO). The optimal 5 wt.% Ag/Ce0.6Zr0.4O2 catalyst presented good NH3-SCO performance with >90% NH3 conversion at temperature (T) ≥ 250°C and 89% N2 selectivity. Despite the irregular block shape and underdeveloped specific surface area (∼60 m2/g), the naked and Ag-modified Ce0.6Zr0.4O2 solid solution still obtained highly dispersed distribution of surface elements analyzed by scanning electron microscope-energy dispersive spectrometer (SEM-EDS) (mapping), N2 adsorption-desorption test and X-ray diffraction (XRD). H2 temperature programmed reduction (H2-TPR) and X-ray photoelectron spectroscopy (XPS) results indicated that Ag-modification enhanced the mobility and activation of oxygen-species leading to a promotion on CeO2 reducibility and synergistic Ag0/Ag+ and Ce4+/Ce3+ redox cycles. Besides, Ag+/Ag2O clusters could facilitate the formation of surface oxygen vacancies that was beneficial to the adsorption and activation of ammonia. NH3-temperature programmed desorption (NH3-TPD) showed more adsorption-desorption capacity to ammonia were provided by physical, weak- and medium-strong acid sites. Diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments revealed the activation of ammonia might be the control step of NH3-SCO procedure, during which NH3 dehydrogenation derived from NHx-species and also internal selective catalytic reduction (i-SCR) reactions were proposed. 相似文献
236.
采用柠檬酸络合法制备La-M-Co-O(M=Mn,Cr,Fe,Ni和Cu)/堇青石催化剂,运用BET,XRD,SEM,H2-TPR和XPS技术对催化剂性能及微观结构进行表征分析,研究考察过渡金属掺杂,掺杂量以及焙烧温度等对催化剂催化氧化性能的影响.结果表明,随着催化剂焙烧温度升高至650℃时,催化剂表面所负载的活性氧化物颗粒最为分散,其氧化活性最佳,且当反应温度为350℃时,催化剂催化氧化氯苯转化率可达96.4%,究其原因是高温焙烧致使催化剂形成LaCoO3钙钛矿型复合氧化物,其复合氧化物的晶体结构有利于催化剂催化氧化氯苯性能的提高. 相似文献
237.
采用不同工艺制备V2O5-WO3-MoOx/TiO2堇青石整体式催化剂,以甲苯和NO为探针分子,考察了Mo的负载量、涂覆方法、粘结剂的种类等制备工艺对整体式催化剂性能的影响,用XRD、SEM-EDS、FT-IR、BET等技术对催化剂进行了表征分析.结果表明,采用涂敷法,以添加量为1%的甲基纤维素为粘结剂所制备的V1W6Mo3/TiO2堇青石蜂窝陶瓷整体式催化剂具有最优活性和稳定性(T90为307℃,负载率为28.26%,脱落率为6.81%),在燃煤烟气中具有优异的同步去除VOCs与NO性能,甲苯去除率可达99%,NO去除率为100%,N2选择性为99%.XRD、SEM-EDS表明V、W、Mo活性组分分布均匀且高度分散.FT-IR证明添加甲基纤维素的整体式催化剂具有优异的抗硫性能. 相似文献
238.
Tong Li Xiange Du Jieqiong Deng Kai Qi Jiandong Zhang Lili Gao Xiuping Yue 《环境科学学报(英文版)》2021,33(10):188-200
Environment-friendly nano-catalysts capable of activating peroxymonosulfate (PMS) have received increasing attention recently. Nevertheless, traditional nano-catalysts are generally well dispersed and difficult to be separated from reaction system, so it is particularly important to develop nano-catalysts with both good catalytic activity and excellent recycling efficiency. In this work, magnetically recoverable Fe3O4-modified ternary CoFeCu-layered double hydroxides (Fe3O4/CoFeCu-LDHs) was prepared by a simple co-precipitation method and initially applied to activate PMS for the degradation of Rhodamine B (RhB). X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), and vibrating sample magnetometer (VSM) were applied to characterize morphology, structure, specific surface area and magnetism. In addition, the effects of several key parameters were evaluated. The Fe3O4/CoFeCu-LDHs exhibited high catalytic activity, and RhB degradation efficiency could reach 100% within 20 min by adding 0.2 g/L of catalyst and 1 mmol/L of PMS into 50 mg/L of RhB solution under a wide pH condition (3.0-7.0). Notably, the Fe3O4/CoFeCu-LDHs showed good super-paramagnetism and excellent stability, which could be effectively and quickly recovered under magnetic condition, and the degradation efficiency after ten cycles could still maintain 98.95%. Both radicals quenching tests and electron spin resonance (ESR) identified both HO? and SO4?? were involved and SO4?? played a dominant role on the RhB degradation. Finally, the chemical states of the sample's surface elements were measured by X-ray photoelectron spectroscopy (XPS), and the possible activation mechanism in Fe3O4/CoFeCu-LDHs/PMS system was proposed according to comprehensive analysis. 相似文献
239.
通过共沉淀法制备了用于湿式氧化乐果农药废水的Cu/Mn复合氧化物催化剂,研究了沉淀剂种类、沉淀温度、焙烧温度和活性组分配比等因素对Cu/Mn复合氧化物催化剂的活性及稳定性的影响,确定了最佳制备条件,利用BET比表面积测定和XRD对催化剂进行了表征。结果表明:优化条件制备的Cu/Mn复合氧化物催化剂催化湿式过氧化氢氧化处理乐果农药废水时,具有较高的催化活性和稳定性。催化剂用量以6 g/L,反应温度80℃,过氧化氢加入量为12.0 g/L,反应时间60 min,COD去除率为89.5%,活性组分溶出量较小。 相似文献
240.
Cr/γ-Al_2O_3对乙酸乙酯的催化燃烧 总被引:1,自引:1,他引:0
使用浸渍法制备不同负载量的Cr/γ-Al_2O_3催化剂,研究乙酸乙酯的催化燃烧.BET,XRD结果表明,Cr在γ-Al_2O_3上负载存在分散阈值效应,负载量在阈值以下时呈单层分散形式,在超过阈值时Cr形成结晶,实验测得单层分散阈值与理论计算一致.Raman结果表明Cr在单层分散时为Cr~(6+),而在非单层分散时为Cr_2O_3.催化乙酸乙酯燃烧的活性研究显示,阈值效应对催化活性有显著影响:催化活性在单层分散阈值时最好,此时活化能最高,指前因子最大. 相似文献