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2019年  第47卷  第2期

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研究论文
摘要:
采用灰熔点仪、X射线荧光仪(XRF)研究了无机非金属P2O5对城市污水污泥与烟煤的混烧灰熔融特性的影响,利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)研究在各混烧温度下灰中含磷矿物在晶体和非晶体间的演变。结果表明,对于Al2O3含量较多且熔点较高的灰样,磷含量的增加可显著降低其灰熔点,P2O5含量在0-4%时影响最大,使其灰熔点降低126℃;但对碱性含量高的灰样的影响较小。低温灰中主要以磷酸铝(AlPO4)晶体为主,温度升高后,与硬石膏(CaSO4)等含钙矿物和赤铁矿(Fe2O3)反应生成晶体Ca3(PO42和玻璃相(Fe2O30.252(P2O50.748,磷含量增加可使灰中玻璃相(Fe2O30.252(P2O50.748增加,是磷降低灰熔点的主要原因。
摘要:
应用量子化学密度泛函理论B3LYP方法,研究了砷与氮氧化物(N2O、NO2和NO)的反应机理。全参数优化了各反应物、中间体、过渡态和产物的几何构型,通过频率分析证实中间体和过渡态的真实性,并通过内禀反应坐标(IRC)计算以进一步确定过渡态。为了得到更精确的能量信息,在B2PLYP水平下计算各结构的单点能,并通过动力学参数深入分析其反应机理。结果表明,砷与三种氮氧化物(N2O、NO2和NO)的反应能垒分别为78.45、2.58、155.85 kJ/mol。在298-1800 K,各反应速率随温度的升高而增大。由于砷与NO2的反应能垒较低,其反应速率大于1012 cm3/(mol·s),说明该反应容易发生且速率极快。砷与N2O和NO的反应,在298-900 K,反应速率随温度的升高明显增加;当温度进一步升高,其增加的趋势有所减缓。
摘要:
采用元素分析、13C NMR、XPS和TG-MS技术考察了氯化亚铬(CrCl2)脱除黄铁矿对桦甸油页岩有机质结构的影响。结果表明,CrCl2可有效脱除有机质中的黄铁矿,脱除率为96.19%。CrCl2对有机质的碳骨架结构影响较小,脱除黄铁矿前后有机质中脂碳、芳碳和羧基/羰基碳的相对含量以及有机质的热解特征温度基本保持不变,但CrCl2可破坏有机质中的C-O键,使C-O/C-OH和O=C-O的含量减少,造成0.98%的有机碳损失和12.54%的有机质损失。CrCl2处理后,有机质的C含量显著增加,H含量稍有增加,O含量显著降低,使得H/C略微降低,O/C明显降低。另外,CrCl2处理后,单位质量有机质中脂碳的含量增加了5.28%,使其热解过程中产生了更多的挥发分,残留的氧化铬对有机质的热分解可能也具有促进作用。
摘要:
This study presents a detailed analysis of the catalytic de-oxygenation of the liquid and gaseous pyrolytic products of two biomasses (beech wood and flax shives) using different catalysts (commercial HZSM-5 and H-Y, and lab-synthesised Fe-HZSM-5, Fe-H-Y, Pt/Al2O3 and CoMo/Al2O3). The experiments were all conducted in a semi-batch reactor under the same operating conditions for all feed materials. BET specific surface area, BJH pore size distribution and FT-IR technologies have been used to characterise the catalysts, while gas chromatography-mass spectrometry (GC-MS), flame ionisation detection (GC-FID) and thermal conductivity detection (GC-TCD) were used to examine the liquid and gaseous pyrolytic products. It was firstly seen that at higher catalyst-to-biomass ratios of 4:1, de-oxygenation efficiency did not experience any further significant improvement. Fe-HZSM-5 was deemed to be the most efficient of the catalysts utilised as it helped reach the lowest oxygen contents in the bio-oils samples and the second best was HZSM-5. It was also found that HZSM-5 and H-Y tended to privilege the decarbonylation route (production of CO), whilst their iron-modified counterparts favoured the decarboxylation one (production of CO2) for both biomasses studied. It was then seen that the major bio-oil components (carboxylic acids) underwent almost complete conversion under catalytic treatment to produce mostly unoxygenated aromatic compounds, phenols and gases like CO and CO2. Finally, phenols were seen to be the family most significantly formed from the actions of all catalysts.
摘要:
The spent residue hydrotreating catalysts were taken out from the different HDM bed axial position of a fixed-bed residue hydrotreating reactor of Petro-China. The coke on spent catalysts were studied by the technologies such as EA, TG, XPS, FT-IR and 13C NMR to get the structure characteristics and parameters. The results showed that the coke on spent residue hydrotreating catalysts located on different beds positions share some characteristics such as the kind of coke, the functional group, but the structure and composition were different from each other. Based on the result of each characterization technique, chemical structure models of coke were established. In order to ensure the accuracy of the structures, a software called gNMR helped to calculate the chemical shifts and predict the NMR spectra of the structure models. The model structures can be corrected to match the experimental results through comparing experimental spectra and the predicted ones.
摘要:
以1-丁基-3-甲基咪唑溴离子液体([Bmim]Br)、磷钨酸(H3PW12O40)和g-C3N4为原料,采用原位沉淀法合成了负载型[Bmim]3PW12O40/g-C3N4催化剂(BPWO/g-C3N4)。通过XRD、FT-IR、UV-vis、氮气吸附、TEM和XPS等手段对催化剂的形貌和结构进行了表征,并以二苯并噻吩(DBT)的正庚烷溶液为模拟油、过氧化氢为氧化剂,考察了各组分负载量、催化剂用量、氧/硫物质的量比(O/S)和反应温度变量等对其氧化脱硫效果的影响。结果表明,BPWO/g-C3N4具有Keggin型杂多阴离子结构特征,BPWO(20%)/g-C3N4催化剂具有最优的对DBT的氧化脱硫性能,在50℃、O/S物质的量比为6.0的条件下反应180 min,可以完全氧化浓度为800 μg/g的含DBT模拟油。同时,该BPWO/g-C3N4催化剂具有良好的重复使用性能,循环使用八次后其对DBT的氧化活性没有明显降低。
摘要:
通过一步水热合成法制备了大比表面积、高脱硫活性的磷钨酸(HPW)负载的金属有机框架HPW@MIL-101(Cr)催化剂,对其进行了FT-IR、XRD和氮吸附等表征,并研究了合成时间、合成温度、酸碱度及HPW负载量等参数对催化剂脱硫性能的影响。结果表明,随着合成时间的延长、合成温度的提高,HPW@MIL-101(Cr)孔道有序度提高;合成温度低于等于140℃时,不能形成MIL-101(Cr)晶体结构;酸性合成条件合成的HPW@MIL-101(Cr)的孔道有序度降低;随着HPW负载量的增加,HPW@MIL-101(Cr)的催化性能呈现先升高后降低的趋势。在12 h、220℃和中性条件下制备得到的负载量为3.5 g的HPW@MIL-101(Cr)催化剂具有最佳脱硫活性;在模拟油20 mL、催化剂用量0.24 g、氧硫比为8和50℃条件下反应120 min,对苯并噻吩、二苯并噻吩和4,6-二甲基二苯并噻吩脱硫率分别为99%、100%和99%;与HPW相比,苯并噻吩脱硫率提高了2.4倍。
摘要:
采用水热后合成法制备了BiVO4/SBA-15催化剂,利用XRD、SEM-EDS和N2吸附-脱附等手段对其进行表征分析,并在自制的光催化反应装置中对其静态光催化氧化脱硫性能进行了研究。结果表明,BiVO4/SBA-15催化剂具有SBA-15分子筛的介孔孔道结构,BiVO4均匀分布在SBA-15分子筛表面。BiVO4/SBA-15催化剂具有良好的催化氧化脱硫性能,在BiVO4负载量为15%、水热合成时间为18 h、530℃下焙烧3 h制备的BiVO4/SBA-15催化剂,对模拟柴油的脱硫率可达95.6%。
摘要:
Dry reforming of methane (DRM) with CO2 is of great significance in the environmental protection and the utilization of natural gas. SiO2 and Al2O3 are two typical catalyst supports used in DRM. To elucidate the effect of these two supports on the catalytic performance, in this work, Ni/SiO2 and Ni/Al2O3 catalysts are prepared by the incipient wetness method and characterized by BET, TEM, H2-TPR, XRD, TG and Raman technologies. The results indicate that the performance of Ni-based catalyst is closely related to the properties of support and the Ni/SiO2 and Ni/Al2O3 catalysts are rather different in their DRM performance. Ni/SiO2 catalyst exhibits higher initial activity but poor stability; its catalytic activity decreases rapidly in 15 h for DRM at 800℃. Because of the weak metal-support interaction, Ni species on the Ni/SiO2 catalyst is present as large Ni particles, which may promote the formation of coke precursors, viz., the multi-carbon Cn species, leading to the fast carbonaceous deposition and catalyst deactivation. In contrast, the Ni/Al2O3 catalyst displays a lower activity but a much higher stability; its activity in DRM keeps stable in 50 h. Although Ni particles in the Ni/Al2O3 catalyst is much smaller, the strong metal-support interaction promotes the formation of NiAlxOy species during the catalyst preparation process, which may lead to a decrease in the content of active Ni species and give the Ni/Al2O3 catalyst a relatively low catalytic activity in DRM; however, the strong metal-support interaction between Ni and Al2O3 is also of benefit to the formation and stabilization of small Ni particles, which can alleviate the carbanceous deposition and afford the Ni/Al2O3 catalyst a better stability.
摘要:
通过调控共沉淀中钼酸铵溶液的酸度制备了系列铁钼催化剂,采用N2吸附-脱附、Raman、XRD、SEM、H2-TPR等方法对催化剂的结构进行了表征,并考察了不同酸度条件下制备的铁钼催化剂的甲醇氧化制甲醛催化活性。结果表明,钼酸铵溶液酸度影响催化剂的粒径、形貌及表层铁、钼物种的分布与富集。恰当的钼酸铵溶液酸度范围,优化了催化剂表层MoO3和Fe2(MoO43物种的比例,改善了催化剂的催化氧化性能,有利于甲醇氧化制甲醛收率和选择性的提高。
摘要:
采用溶胶-凝胶法(sol-gel)制备了一系列具有不同RuO2含量的RuO2-Fe2O3催化剂,并将其应用于氨选择性催化氧化(NH3-SCO)研究中。结果表明,所有RuO2-Fe2O3催化剂都表现出较好的低温活性,且RuO2含量对催化剂的NH3催化氧化活性影响显著。此外,利用BET、XRD、H2-TPR和DRIFTS等表征手段研究了催化剂的物理化学性质和催化活性之间的关系。结果表明,RuO2的加入增大了催化剂的比表面积。RuO2与Fe2O3之间存在的协同效应提高了催化剂的氧化还原能力,从而提高了催化剂的氨氧化活性。同时,RuO2含量对催化剂表面酸性影响很大,且催化剂表面主要存在Lewis酸性位点。
摘要:
通过低温燃烧法(LCS)制备了不同金属硝酸盐与柠檬酸物质的量比的系列Mn-CeOx(LCS)锰铈催化剂,将其与共沉淀法(CP)制备的Mn-CeOx(CP)锰铈催化剂相对比,结合XRD、XPS、FESEM和H2-TPR等技术表征,对其NH3-SCR脱硝催化性能进行了研究。结果表明,金属硝酸盐与柠檬酸的物质的量比是影响Mn-CeOx(LCS)催化剂脱硝性能的重要因素。虽然两种催化剂中的锰氧化物组分均为无定型,但相较于Mn-CeOx(CP),Mn-CeOx(LCS)表面具有较高的锰含量与Oα/(Oα+Oβ)比,其脱硝催化性能也较高;同时,Mn-CeOx(LCS)锰铈催化剂上有更多的多级孔,有利于气体在催化剂上的吸附和反应。硝酸盐与柠檬酸物质的量比为36:22的Mn-CeOx(LCS)锰铈催化剂在80-180℃下脱硝率可达75%-100%;即使通入SO2,180℃下的脱硝率仍可稳定于74%。
摘要:
在模拟水泥分解炉的实验台架上研究CO2浓度(体积分数0-35%)对污泥再燃还原性气体析出特性及其对污泥与污泥焦还原NO反应的动态变化规律的影响。结果表明,污泥再燃产生的还原性气体主要为HCN、NH3、CH4及CO;当CO2浓度从0增加到25%时,由于CO2与污泥焦气化作用增强,导致HCN、NH3及CH4的析出量缓慢下降,而CO析出量显著增加,最终促进NO还原率从51%增加至61%;继续增加CO2浓度至35%,由于CO2的辐射吸收导致局部热不稳定性增强,气化作用的减弱导致CO析出量下降,且HCN析出量有较大幅度下降,NH3析出量变化不大,CH4析出量有一定幅度上升,综合影响使得NO的还原率逐渐下降至55%。研究表明,实验室条件下污泥再燃能较高效地对烟气中NO进行还原;机理研究表明,污泥再燃过程中同时存在对NO的气气均相还原反应和气固异相还原反应,实验确定污泥焦对NO的气固异相还原率仅为18%,因此,污泥脱硝以气气均相还原反应为主。
摘要:
以三聚氰胺、间苯三酚和甲醛为原料,通过水热缩聚反应合成了三聚氰胺酚醛纤维(PMF),考察了温度对PMF合成的影响。以扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N2吸脱附和傅里叶变换红外(FT-IR)光谱等表征了PMF的形貌和结构,并采用体积法测定不同温度下CO2和N2在PMF上的单组分吸附平衡等温线。结果表明,在393 K下合成的PMF具有较大的比表面积(64 m2/g)和较高的CO2吸附量(1.83 mmol/g,298 K、118 kPa)。穿透柱实验表明,在298 K、200-600 kPa,CO2-N2混合气在PMF上均可实现有效分离。将PMF在873 K下,N2、H2及水蒸气等多种气氛中进行后处理,其比表面积和微孔孔容均显著增加,其中,在15% H2O气氛中处理后,样品CO2吸附量提高至2.83 mmol/g(298 K、118 kPa)。
摘要:
通过在锐钛矿TiO2载体表面上负载Cu-BTC(BTC,1,3,5-苯甲酸)前驱体,还原处理制备光催化剂CuO-Ti3+/TiO2(Cu-TiMB),对其在可见光条件下气相甲苯净化催化性能进行了研究。结果表明,该改良方法制备的CuO-Ti3+/TiO2(Cu-TiMB)催化剂的活性是浸渍法所得催化剂CuO-TiO2(Cu-TiD)的2.68倍。CuO-Ti3+/TiO2(Cu-TiMB)具有更大的比表面积(147 m2/g)和较小的颗粒粒径(0.45 μm),呈现多孔状,CuO的分散度较高;催化剂表面Ti3+提供了大量的氧缺位,在400-800 nm波段的光响应能力显著增强。CuO-Ti3+/TiO2(Cu-TiMB)催化剂中Cu2+、Cu+与Ti3+形成的异质结构进一步增多了氧缺位数量,延缓e--h+的复合时间;氧缺陷增强了捕获吸附氧能力,通过金属氧化物价态变化增强化学吸附能力,提高了光催化性能。