Combination of biodiesel-ethanol-diesel fuel blend and SCR catalyst assembly to reduce emissions from a heavy-duty diesel engine

In this study, the efforts to reduce NOx and particulate matter （PM） emissions from a diesel engine using both ethanol-selective catalytic reduction （SCR） of NOx over an Ag/Al2O3 catalyst and a biodiesel-ethanol-diesel fuel blend （BE-diesel） on an engine bench test are discussed. Compared with diesel fuel, use of BE-diesel increased PM emissions by 14% due to the increase in the soluble organic fraction （SOF） of PM, but it greatly reduced the Bosch smoke number by 60%-80% according to the results from 13-mode test of European Stationary Cycle （ESC） test. The SCR catalyst was effective in NOx reduction by ethanol, and the NOx conversion was approximately 73%. Total hydrocarbons （THC） and CO emissions increased significantly during the SCR of NOx process. Two diesel oxidation catalyst （DOC） assemblies were used after Ag/Al2O3 converter to remove CO and HC. Different oxidation catalyst showed opposite effect on PM emission. The PM composition analysis revealed that the net effect of oxidation catalyst on total PM was an integrative effect on SOF reduction and sulfate formation of PM. The engine bench test results indicated that the combination of BE-diesel and a SCR catalyst assembly could provide benefits for NOx and PM emissions control even without using diesel particle filters （DPFs）.     

催化臭氧化降解技术中的两个问题

探讨了有机物特性及中间产物H2O2在催化臭氧化中的作用。结果表明,有机物在自由基链反应过程中的特性直接影响催化臭氧化的降解效率。当目标有机物是对链反应具有促进作用的甲酸时,自由基引发反应可以明显提高甲酸的臭氧化效率。当目标有机物是对自由基链反应具有抑制剂作用的乙酸时,O3和Fe^2＋/O3对乙酸有着相似的降解效率。以上结果表明,自由基引发反应并不是臭氧化降解效率提高的充分条件。另外,当臭氧化过程有H2O2产生时,必须考虑类Fenton反应对臭氧化效率的影响。     

生物质催化气化制氢技术研究

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。     

石化废水深度处理用臭氧催化氧化体系的研究＊

文章就臭氧催化氧化体系在石化废水处理中的作用进行了深入研究,对催化剂载体、催化剂配伍体系以及臭氧的投加方式进行了优化筛选。根据实验,多元催化掺杂体系较一元催化体系氧化效果好,CODCr的去除率可由一元催化时的20%提高到多元催化时的33%;在臭氧的投加方式上,分段投加要优于单级投加,臭氧投加分配比例为6∶3∶1时,CODCr的去除率可由单一投加时的9%提高到分级投加时的19%。     

链状高分子金属配合物催化氧化苯乙烯

利用链状Salen型高分子希夫碱金属配合物PLSBM(M:CoⅡ,MnⅡ,ZnⅡ,CuⅡ)作为催化剂,催化分子氧氧化苯乙烯.结果表明,在不添加任何助剂和共还原剂的条件下,氧化产物以苯甲醛(Ⅰ)和环氧苯乙烷(Ⅱ)为主,PLSBCuⅡ具有最佳的催化活性和产物选择性.考察了影响氧化反应的因素,发现在反应温度为90℃、反应时间为9h和催化剂与苯乙烯用量比为1mg∶2mL时,苯乙烯具有最优的转化率(61％)和产物选择性(Ⅰ:57％,Ⅱ:36％).     

钙钛矿型催化剂La_（0.8）M_（0.2）CoO_3（M=Sr、Ce、Ba、Ca）催化燃烧VOCs的活性与抗硫性研究

用柠檬酸溶胶-凝胶法制备了La0.8M0.2CoO3（M=Sr、Ce、Ba、Ca）4种钙钛矿型复合氧化物催化剂.甲苯催化燃烧活性测试表明,4种催化剂均具有很好的催化活性,转化率达到90%时反应温度都在340℃以下,比LaCoO3下降20℃—70℃,催化性能依次为：La0.8Sr0.2CoO3〉La0.8Ce0.2CoO...     

Promotional catalytic activity and reaction mechanism of Ag-modified Ce0.6Zr0.4O2 catalyst for catalytic oxidation of ammonia

Ce_1-xZr_xO₂ 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/Ce_0.6Zr_0.4O₂ 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 Ce_0.6Zr_0.4O₂ 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 NH_x-species and also internal selective catalytic reduction (i-SCR) reactions were proposed.     

La-M-Co-O/堇青石催化剂的制备及催化氧化氯苯

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.     

钒基催化剂同步去除燃煤烟气中甲苯与NOx研究

采用不同工艺制备V₂O₅-WO₃-MoO_x/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.     

Efficient degradation of Rhodamine B by magnetically recoverable Fe3O4-modified ternary CoFeCu-layered double hydroxides via activating peroxymonosulfate

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.