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2018年  第46卷  第4期

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研究论文
摘要:
基于准东煤中Na/Ca的赋存形态,采用管式加热炉研究了准东煤中Na/Ca在惰性气氛下的释放特性和形态转变。结果表明,水溶态Naw在加热温度t ≤ 600℃时先转变成不可溶态Nare,随着温度升高,不可溶态Nare又重新转变成水溶态Naw,当加热温度t > 800℃时,Na大量释放。酸溶态Caac在加热温度t ≤ 700℃时先分解生成CaO并且与其他矿物组分反应转变成不可溶态Care,随着温度升高,不可溶态Care逐渐转变成酸溶态Caac和水溶态Caw。相同温度条件下,Ca的释放率低于Na的释放率,少量酸溶态有机Ca随挥发分释放而以气相形式释放。
摘要:
选取典型的准东煤五彩湾煤为研究对象,在马弗炉内制备400-1200℃的燃烧灰和再热灰,采用K型热电偶测量燃烧过程中样品表面温度,通过XRF、XRD分析获得灰的成分和结晶形式,取部分灰样逐级萃取,通过微波消解及电感耦合等离子体质谱仪(ICP-MS),获得灰中钠的赋存特性。结果表明,燃烧和再热灰在成分和晶体形式上差异显著,再热灰钠含量明显高于燃烧灰且灰熔点偏低;随着温度升高灰中钠盐总量明显减少,其中,水溶钠、醋酸铵溶钠迅速减少,而盐酸溶钠含量先增加后减少,不可溶钠增加,释放的钠以可溶钠为主;加热温度和时间影响钠的释放,燃烧反应放热导致煤粉表面温度超过环境温度200℃以上,是钠盐过多释放的主要原因。
摘要:
基于热重分析仪考察了神府烟煤焦、稻草焦和神府烟煤-稻草混合焦样气化反应活性及共气化过程协同行为。并借助电感耦合等离子体发射光谱仪和扫描电子显微镜-能谱仪联用装置探讨了共气化过程活性矿物组分的迁移转化特性,以关联解释共气化协同行为演变。结果表明,与煤焦单独气化相比,稻草焦掺混有利于提高煤焦整体气化反应活性。混合焦样共气化过程协同行为随碳转化率的提高呈先逐渐减弱的抑制作用,达到某一碳转化率(记为转折碳转化率)后呈不断增强的协同促进作用,且转折碳转化率随气化温度升高而提高。神府烟煤-稻草混合焦样共气化过程协同行为演变主要归因于共气化过程活性K和Ca转化特性的共同影响。神府烟煤-稻草混合焦样共气化整体协同行为呈协同促进作用,并随气化温度的升高而减弱。
摘要:
采用高分辨率透射电镜-数字图像分析技术HRTEM-DI研究了焦炭微晶结构。焦炭微晶结构参数中的长度、曲率和倾角,可分别用来表达焦炭微晶大小、微晶片层的有序度和微晶堆砌有序度。提出的表征焦炭微晶大小和有序度的结晶指数,能够很好地反映焦炭微晶结晶程度对反应性的影响。
摘要:
以某催化裂化油浆为原料,通过二烯值和溴价分析方法测定了其四组分和五个馏分中共轭烯烃(双键)和烯烃(双键)的含量;同时结合紫外光谱法、核磁共振氢谱法(1H-NMR)对其四组分和五个馏分中的烯烃类型和含量进行了表征和测定。结果表明,催化裂化油浆中的确存在烯烃(双键)和共轭烯烃(双键),其烯烃(双键)和共轭烯烃(双键)的含量高达21%和6%,四组分中的共轭烯烃(双键)含量依次增多,五个馏分中共轭烯烃(双键)的含量在5%左右,且四组分和五个馏分中烯烃(双键)的含量均呈现先减小后增大的趋势。同时,不同组分和不同馏分之间正构α-烯烃和内烯烃的含量也存在差异。
摘要:
采用水热晶化法制备了HUSY@MFI核壳结构复合分子筛。通过XRD、SEM、N2吸附-脱附、NH3-TPD及吡啶吸附红外等手段表征催化剂的结构和性质。结果表明,HUSY@MFI晶粒在形貌上呈椭球状,表面是鳞片状结构的MFI型分子筛,里面是光滑的HUSY型分子筛,焙烧模板剂前几乎没有或只有很少量的N2能进入其孔道结构,致密的壳层MFI覆盖在HUSY型分子筛表面,形成了新的弱酸位,而中强酸强度和酸类型并没有受到影响,复合分子筛的表面酸量及总酸量减少。将所制备的HUSY@MFI复合分子筛催化剂应用于以离子液体1-乙基-3-甲基咪唑氯盐([Emim]Cl)为溶剂的纤维素水解反应中,与HUSY催化的纤维素水解相比,HUSY@MFI复合分子筛催化纤维素水解反应的速率较慢,葡萄糖收率由30.9%提高到41.3%。
摘要:
In this work, series of Ni/γ-Al2O3 catalysts with or without Cu and Mo components were prepared, characterized and tested for the hydrodeoxygenation of fatty acid methyl esters (FAME) to hydrocarbons. The effects of Cu and Mo loading, impregnation sequence with sequential impregnation and co-impregnation involved and reaction conditions on catalytic performance were investigated. According to the TG data, the spent 20Ni-6Cu/γ-Al2O3 catalyst gives less weight loss than the spent 20Ni/γ-Al2O3 catalyst, which indicates that the addition of copper inhibits the carbon deposits behavior on catalyst surface during reaction. For 20Ni-6Cu/γ-Al2O3 and 20Ni-6Cu-nMo/γ-Al2O3(n=2, 5, 8 and 12) catalysts, NH3-TPD analysis shows that the addition of molybdenum phase has significant impact on the acid sites of γ-Al2O3. When the loading of molybdenum is 5%, a new acid site is observed corresponding to the medium strength acid site. The Cu and Mo modified catalysts demonstrate better catalytic performance than Ni/γ-Al2O3 catalysts. Based on XPS results, Cu in the catalysts exists in the Cu2+ and Mo in the catalysts has two states:Mo4+ and Mo6+, and different impregnation sequences may influence the actual element composition of active phase on the surface of catalysts. In addition, the conversion of FAME and yield of alkane are related to the catalysts prepared with different impregnation sequence. Among all the catalysts, the trimetallic 20Ni-6Cu-5Mo/γ-Al2O3 prepared by sequential impregnation (the former Ni and Cu impregnation, the latter Mo impregnation) exhibits optimal catalytic performance. Under appropriate reaction conditions 350℃, 2.5 MPa, WSHV=2.0 h-1, H2/oil ratio=1250 mL/mL, the conversion of FAME and yield of alkane are 98.4% and 94.2%.
摘要:
The essential role of Co on the MoS2 catalyst in selective hydrodesulfurization (HDS) of FCC gasoline was investigated with ammonium tetrathiomolybdate supported on alumina modified with various amount of Co sulfide. According to the data obtained by XRD, HRTEM, XPS, H2-TPR and Py-FTIR analysis, the Co species could significantly affect the microstructure and composition proportion of the active phase, and thus induced the enormous differences in catalytic properties. The evaluation results demonstrated that the Co atoms tending to form the CoMoS phase as Co/Mo(atomic ratio) < 0.2 could greatly improve the HDS activity, but slightly improve the hydrogenation (HYD) activity of olefins. The spillover hydrogen produced by the formation of Co9S8 phase as 0.2 < Co/Mo(atomic ratio) < 0.6 greatly improved the HDS activity, but showed almost no effect on the HYD of olefins. The excess Co could inevitably form some large size Co9S8 phase as Co/Mo(atomic ratio) > 0.6, which would hinder the mutual contact of the reactants and the active sites, and thus lead to the decrease of the HDS activity and selectivity. The obtained results were useful for developing highly effective hydrotreating catalyst.
摘要:
以液相离子交换法制备了一系列不同Cu负载量的CuNaY分子筛;采用XRD及N2吸附-脱附表征分子筛的微观结构和织构性质,采用动态吸附法考察其对噻吩模拟油的吸附脱硫性能,结合NH3-TPD和Py-FTIR方法对CuNaY分子筛的酸量和有效Cu+物种进行定量分析,研究了CuNaY分子筛的表面酸性和铜物种形态结构对其吸附脱硫性能的影响机制。结果表明,通过改变铜负载量可有效调控改性Y分子筛的表面酸性以及铜物种化学形态;适量铜物种的引入可以最大限度的形成有效吸附位,从而获得最优吸附脱硫性能,而过量的Cu物种会在Y分子筛笼内形成多核铜物种结构,导致有效吸附位点的减少,影响其对噻吩的吸附能力。
摘要:
采用CO与金属钴在温度280℃,压力2 MPa的条件下反应48 h后制备得到单相Co2C催化剂。通过XRD、H2-TPR、TEM和XAS对催化剂的结构和组成进行表征并考察了单相Co2C催化剂在费-托合成反应中的稳定性与催化性能。结果表明,随着费-托合成反应的进行,Co2C催化剂的活性缓慢上升,同时伴随着产物中甲烷的选择性逐渐降低,C5+的选择性逐渐升高。对比反应前后催化剂发现,反应后的催化剂为Co2C和少量金属Co的混合相,表明在费-托合成反应条件下,单相Co2C会发生部分分解,生成的金属Co会导致CO的转化率和产物的选择性发生变化。
摘要:
通过水热合成法制得不同硅镓比的GaZSM-5分子筛,经酸交换后压片成型,得到甲醇转化制烃类的GaZSM-5催化剂。采用XRD、SEM、FT-IR、XPS、ICP、低温氮气吸附-脱附、NH3-TPD和Py-FTIR技术对其进行了表征,并在连续流动固定床反应器上进行MTH反应性能评价。结果表明,分子筛中Ga物种主要以骨架Ga和骨架外表面游离态的Ga2O3两种状态存在。凝胶SiO2/Ga2O3配比为60合成所得GaZSM-5分子筛催化剂酸性适中,酸量为0.62 mmol NH3/g,B酸和L酸比值为4.88,形成较大的晶间介孔孔容,达到0.51 cm3/g;具有高的MTH活性稳定性,在相同评价条件下,催化剂寿命最高可达到456 h。与AlZSM-5相比,GaZSM-5的酸性弱,能够抑制积炭生成;纳米GaZSM-5的晶间介孔改善了扩散性能,进一步提高反应活性稳定性,催化剂寿命延长120 h。
摘要:
Amorphous alloy NiP and its carbon composite catalysts NiP/C and NiP/reduced graphene oxide (RGO) were successfully one-pot synthesized using NaH2PO2 and NiSO4 as phosphorus and nickel source, respectively. The electrocatalysts were characterized with transmission electron microscope (TEM), X-ray diffraction spectrometer (XRD), inductively coupled plasma analysis (ICP) and thermogravimetric analysis (TG), respectively. The hydrogen evolution reactions (HER) performance of the electrocatalysts was evaluated with a linear sweep voltammetry method in both acidic and alkaline solution. Among them, NiP/RGO elctrocatalyst exhibited 89.0 mV onset overpotential and Tafel slope 135.1 mV/decade in acidic solution, as well as 116.1 mV onset overpotential and Tafel slope 122.4 mV/decade in alkaline solution with excellent long-term stability. Results indicated that the NiP/RGO was a very active catalyst.
摘要:
采用原位合成法在γ-Al2O3载体上合成了锌铝水滑石,再经浸渍法制备了Cu/Zn-Al、Ce/Cu/Zn-Al、Cu/Ce/Zn-Al和Cu-Ce/Zn-Al催化材料,使用XRD、XRF、SEM、氮吸附,XPS、H2-TPR和N2O滴定等手段对其进行了表征,探讨了Ce的浸渍顺序对Cu/Zn-Al水滑石衍生材料甲醇水蒸气重整制氢反应催化性能的影响。结果表明,Ce的浸渍顺序主要影响催化剂的还原性质,进而影响了其催化性能。其中,Ce/Cu/Zn-Al催化剂的催化性能最佳,在250℃、水醇物质的量比为1.2、甲醇气体空速为800 h-1的条件下,甲醇转化率达到100%;与Cu/Zn-Al催化剂相比,甲醇转化率提高了近40%。
摘要:
提出了电催化作用下甲烷水蒸气催化重整的新工艺。基于工业常规Ni基催化剂,采用等体积浸渍法,以Ni为活性组分,γ-Al2O3为载体,MgO、CaO为助剂,制备了Ni/γ-Al2O3、Ni-MgO/γ-Al2O3和Ni-CaO/γ-Al2O3催化剂,考察了电流强度、重整温度、水蒸气与甲烷的物质的量比(水碳比,S/C)对不同催化剂的CH4转化率、H2产率、CO选择性和催化剂稳定性的影响。结果表明,电催化工艺有着良好的普适性,电流的引入能够提升CH4转化率、增加H2产率,尤其在低温下电流的促进作用显著。在三种催化剂中,Ni-CaO/γ-Al2O3催化效果最佳,在电流为4.5 A、S/C为3、重整温度为700℃时,CH4转化率就高达95%以上。稳定性测试表明,电流的通入还能显著提高催化剂的稳定性,延缓催化剂的积炭失活。通过对催化剂的分析表征,发现电流的通入提升了催化剂中NiO的还原程度,同时抑制了反应过程中NiCx向石墨炭的转化,从而可延缓催化剂因积炭覆盖反应活性位点而造成的失活。
摘要:
采用松木热解生物炭为模板构筑Fe-Ni复合载氧体(Fe-Ni/BC),并与溶胶-凝胶法制备的NiFe2O4载氧体(NiFe2O4/SG)对比,采用SEM、XRD、XPS、BET、H2-TPR、TG-redox循环等表征方法考察载氧体的物理、化学性质,并在固定床上进行化学链制氢循环实验。结果表明,Fe-Ni/BC载氧体为Ni0.6Fe2.4O4与Fe2O3的混合晶体,保留了生物炭骨架并形成了大孔结构。与NiFe2O4/SG相比,Fe-Ni/BC平均粒径更小,比表面积更大,吸附氧含量更高,更有利于氧的释放。在固定床实验过程中,Fe-Ni/BC表现出更强的化学链制氢与抗积炭性能,其最大产氢速率是NiFe2O4/SG的1.58倍,制取H2的相对浓度可达到99.5%以上。