双金属NiFe/γ-Al2O3催化月桂酸甲酯脱氧的研究

采用浸渍法制备Ni10/γ-Al₂O₃、Ni₅-Fe₅/γ-Al₂O₃和Fe₁₀/γ-Al₂O₃催化剂,研究各催化剂对月桂酸甲酯的加氢脱氧(HDO)性能。通过H₂程序升温还原(H₂-TPR)、X射线衍射(XRD)和H₂程序升温脱附(H₂-TPD)对制得的催化剂和前驱体进行表征,证实双金属催化剂中形成NiFe合金且其有助于提高催化性能,阐明Ni与Fe之间的相互协同作用。Fe物种对Ni催化剂的月桂酸甲酯加氢性能和产物选择性具有显著影响,在低反应温度下表现出明显优于单金属催化剂的催化性能。在反应温度为340℃时,Ni₅-Fe₅/γ-Al₂O₃催化剂的月桂酸甲酯转化率为86.79%,烷烃化合物选择性达90%以上。     

Ag/Al2O3(Li2O)/g-C3N4光催化乙醇制取环氧乙烷

本文制备了一系列Ag/Al₂O₃(Li₂O)/g-C₃N₄复合催化剂,考察了其可见光催化乙醇制取环氧乙烷的性能。Li₂O可调变Al₂O₃表面的酸性,从而降低了主要副产物乙醛的选择性。Ag/Al₂O₃(Li₂O) 在g-C₃N₄上的负载量对产物环氧乙烷的选择性有较大影响,当Ag/Al₂O₃(Li₂O) 负载量为5wt%时,乙醇具有较高的转换率,且环氧乙烷的选择性高达100%。     

Mo2C/Al2O3的制备及其催化二甲醚水蒸气重整性能研究

通过浸渍沉淀法结合程序升温碳化法制备了Mo₂C/Al₂O₃复合催化剂,并应用于二甲醚水蒸气重整催化体系的研究。考察了二甲醚水解催化载体、水解功能组分Al₂O₃与重整功能组分Mo₂C的比例、反应物浓度对复合催化剂活性的影响。结果表明,β-Mo₂C与γ-Al₂O₃载体以Mo/Al = 1/1耦合后能够高效催化二甲醚重整制氢,其最佳进料水醚比为5,最适反应温度为400℃。     

Ni-xFe/Mayenite促进CO2-CH4重整的稳定性调控实验研究

采用湿法混合-浸渍法制备了一系列 Ni-xFe/mayenite(Ca₁₂Al₁₄O₃₃)催化剂,并在 700 ℃、常压、CH₄/CO₂为 1 的条件下进行了干重整实验研究．系统考察了金属负载量、金属组分等对干重整活性和稳定性的影响．其中7.5% Ni-0.1Fe/mayenite 能够得到接近热力学平衡值的 CO₂和 CH₄转化率(分别为 90.1%、86.0%),氢碳比为0.94.Ni-x Fe/mayenite 的活性随着 Ni 负载量从 5%增加到 10%显著提高;进一步增加到 30%时,活性提升有限．Ni 负载量较高的 Ni/mayenite 更容易发生碳沉积,导致反应器堵塞,而 Ni-x Fe/mayenite 在干重整过程中稳定性显著提高．Fe 掺杂提高催化剂表面氧浓度,形成 Ni-Fe 合金有利于 Ni 位点分散,抑制 CH₄过快裂解;钙铝石作为载体,促进了 CO₂与金属之...     

梨木炭蒸汽气化制取富氢燃气的试验研究

生物质气化技术已得到广泛的应用,但气化过程产生的焦油会影响设备稳定运行。为了大幅减少焦油的干扰,以梨木的热解炭为原料,在管式炉中进行水蒸气气化制取富氢燃气试验研究,探究了反应温度、K₂CO₃添加量及利用次数对气化特性的影响。结果表明：900℃时H₂的产气量为2.19 L/g,合成气中H₂含量超过58%;K₂CO₃添加量为10%时产气效果最佳,此时合成气中H₂+CO含量达到了88.5%。当K₂CO₃催化剂在第三次利用时,仍有较好的催化效果。     

锰基UIO-66催化气化H2O2协同氧化甲苯的研究

利用原位沉积法制备了不同掺杂比例的Mn负载UIO-66材料并协同气化过氧化氢脱除甲苯气体．采用XRD、SEM、TEM、XPS、ICP等技术对Mn-UIO-66的物理化学特性进行了表征．催化实验确定了Mn-UIO-66/H₂O₂的最佳反应温度、过氧化氢浓度，同时还探究了质量空速变化对甲苯催化降解的影响．EPR测试揭示了Mn-UIO-66/H₂O₂体系中羟基自由基产量与催化剂中锰元素的负载量呈正比例关系．GC-MS分析了甲苯脱除过程中的中间产物，并提出甲苯脱除过程中可能的反应路径.     

中国南方典型农业生物质结渣特性实验研究

实验研究了广东省典型农业生物质稻杆、甘蔗渣/叶的燃烧结渣特性。采用GB/T212-2001和ASTM E1755标准进行灰化实验,采用角锥法和一步法检测生物质的熔融特性。实验结果证实ASTM的低温灰化标准更适合稻杆类高无机盐含量的生物质原料。稻杆中碱金属氧化物含量达20%以上,是导致灰渣粘结和熔融的主要因素。由于角锥法灰熔点检测法提前将部分碱金属和Cl元素转化和析出,导致检测结果远高于实际燃烧的熔融温度;相比而言,一步法更具有直观性和指导作用。通过一步法实验获得稻杆临界结渣温度为700℃ ~ 750℃,甘蔗渣为850℃ ~ 900℃,甘蔗叶为900℃ ~ 950℃。CaO和Al₂O₃添加剂对于生物质燃烧过程具有一定的抗结渣功能,CaO通过与SiO₂ (s) 反应生成高熔点的固态Ca₃Si₂O₇ (s) 和MgOCa₃O₃Si₂O₄ (s),因此能消耗物料周围的SiO₂ (s),抑制低温共融;Al₂O₃则通过生成高熔点温度的固态KAlSiO₄和固态KAlSi₂O₆,减少低温共熔现象的发生。     

添加生物质气化气的选择性非催化还原研究

提出利用生物质气化气为选择性非催化还原技术（SNCR）反应的添加剂,并进行相应的反应动力学计算。计算结果表明生物质气化气作为添加剂可以提高低温条件下SNCR反应的脱硝效率。生物质气化气主要成分为H₂、CH₄和CO,其中H₂和CH₄对温度窗的作用明显,CO的效果较小。各种气体成分主要通过促进OH基元生成来促进相对较低温度下脱硝反应过程的进行。     

联合CO2捕集的生物质化学链气化制备合成气系统分析

本文提出以Fe₂O₃为载氧体、以CaO捕集CO₂的生物质化学链气化系统,利用Aspen Plus软件对该系统进行了模拟,以合成气组成（干基）、合成气氢碳比、含碳产物的碳摩尔分布、冷气效率及收率等为系统性能评价指标,重点分析了燃料反应器温度（T_FR）、载氧体Fe₂O₃与生物质碳摩尔比（Fe₂O₃/C）、水蒸气与生物质碳摩尔比（Steam/C）、CaO与生物质碳摩尔比（CaO/C）等系统参数对固体生物质化学链气化系统的影响。结果表明,在T_FR = 825℃、Fe₂O₃/C = 0.5、Steam/C = 0.71和CaO/C = 0.26条件下,合成气制备系统性能较优,合成气中H₂和CO₂含量分别为55.2%和15.4%,氢碳比为1.93,冷气效率为78.2%,被CaCO₃捕集的生物质碳为18.2%,收率（湿气基）为1.95 Nm³/kg_biomass,其中合成气中H₂和CO收率为1.24 Nm³/kg_biomass。     

基于Ni/Al2O3整体式催化剂的生物质气化合成气甲烷化研究

以生物质气化模拟合成气H2/CO/N2为原料气,以堇青石蜂窝陶瓷为基体制备Ni/Al2O3整体式催化剂,通过扫描电镜(SEM)、比表面积(BET)、X射线衍射(XRD)、程序升温反应法(TPR)、热重分析(TG)等表征分析手段,考察催化剂制备方法(浸渍法和溶胶-凝胶法)、温度(250~550℃)及空速GHSV(6000~14000 mL/(g·h))对催化剂甲烷化性能的影响。结果表明:浸渍法制备的Ni/Al2O3催化剂(DIP-Ni/Al2O3)与溶胶-凝胶法制备的Ni/Al2O3催化剂(SGNi/Al2O3)相比,前者甲烷化性能较好。在H2、CO、N2物质的量之比为3∶1∶1且空速为10000 mL/(g·h)条件下,浸渍法制备的Ni/Al2O3催化剂在400℃时甲烷化性能最佳,且该条件下CO转化率为98.6%,CH4选择性为90.9%。当H2、CO、N2物质的量之比为3∶1∶1且温度为400℃时,在实验空速范围内,浸渍法制备的Ni/Al2O3催化剂CO转化率和CH4选择性均基本稳定在90%,甲烷化性能较好。     

Hydrogen production from sorption enhanced steam reforming of ethanol using bifunctional Ni and Ca-based catalysts doped with Mg and Al

This work evaluated the performance of nickel-based catalysts supported on CaO and CaO–MgO–Al₂O₃ in the sorption enhanced steam reforming of ethanol (SESRE) aiming the production of high purity H₂. The catalysts were prepared by sol-gel method and characterized by different methods: Temperature programmed reduction (TPR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with chemical element mapping, N₂ physisorption and CO₂ capture capacity determined by thermogravimetric analysis (TGA). XRD analysis showed that the predominant phases were CaO, MgO, CaCO₃, Ca(OH)₂ and NiO in the calcined samples and Ni⁰ in the reduced and passivated samples. TPR profiles indicated that all catalysts presented a high degree of reduction (Ni/CaMgAl-68 > Ni/CaMgAl-79 > Ni/Ca), although Ni/CaMgAl-X samples presented high reduction temperatures indicating the formation of NiAl₂O₄. The addition of MgO and Al₂O₃ to CaO was very beneficial since the deactivation coefficients, calculated by the TGA data modeling, decreased by a factor of 3.8 for Ni/CaMgAl-79 and by a factor of 4.3 for Ni/CaMgAl-68 when compared to the Ni/Ca catalyst. The catalytic tests in the SESRE showed that Ni/CaMgAl-79 catalyst had the best performance since it had the longest high purity hydrogen production time. In the pre-breakthrough period, the H₂ mole fractions were close to 90% for all samples during all reaction cycles. After the reaction-regeneration cycles, the average crystallite size of CaO estimated by XRD increased around 38, 6 and 35% for Ni/Ca, Ni/CaMgAl-79 and Ni/CaMgAl-68, respectively. Thus, adding a dopant to the sorbent material proved to be an effective strategy to obtain a more stable catalyst capable to produce hydrogen of high purity.     

Multi-size distributed Ni catalyst embedded in SiCxOy film by inverse microemulsion-precipitation method for ethanol steam reforming

Ni/SiC_xO_y catalysts with multi-size distribution of Ni particles, were prepared and supported on porous SiC ceramics by a combination of inverse microemulsion and precipitation methods, as reaction microchannels for ethanol steam reforming (ESR). The microstructure, phase composition, reduction performance, hydrogen production performance of ESR, and the type and growth of carbon deposition were investigated for Ni/SiC_xO_y catalysts. The Ni catalysts embedded in SiC_xO_y film with the appropriate amount of precipitant exhibited multi-size distribution and minimal particle size. The initial ethanol conversion rate and H₂ selectivity of Ni/SiC_xO_y catalysts during ESR reaction were 100% and 75%, respectively, remaining 95% and 69.2% after 20 h, respectively. Raman and SEM results indicate that Ni/SiC_xO_y catalysts with appropriate amounts of precipitant tended to grow more loosely arranged carbon nanowires. The combination of inverse microemulsion and precipitation methods produced smaller and multi-size distributed Ni/SiC_xO_y catalysts with superior durability and hydrogen production performance in ESR reaction.     

Tuning the metal-support interaction of methane tri-reforming catalysts for industrial flue gas utilization

This study investigates the role of metal-support interaction (MSI) in the performance of Ni/TiO₂, Ni/SBA-15, Ni/MgO, and Ni/Al₂O₃ catalysts for the tri-reforming of methane (TRM) reaction. To impart weak metal-support interaction (WMSI), the catalysts were calcined at 400 °C. While calcination at 850 °C or above temperature generated strong metal-support interaction (SMSI) in each catalyst. The experimental results reveal that Ni/TiO₂ and Ni/MgO catalysts having WMSI displayed high initial activity due to the higher extent of reduction and Ni dispersion. However, these catalysts deactivated during 10 h reaction run. On the other hand, the performances of Ni/TiO₂ and Ni/MgO catalysts having SMSI were unsatisfactory. For Ni/SBA-15 catalyst system, catalysts having weaker MSI were more active than the catalyst having stronger MSI. However, the stability of Ni/SBA-15 catalysts was governed by Ni confinement in the pores of SBA-15 rather than the strength of MSI. Ni/Al₂O₃ having SMSI had monodispersed Ni atoms in close association with Al₂O₃, which resulted in higher reforming activity compared to that of Ni/Al₂O₃ having WMSI. Overall, the present study asserts that the strength of MSI has a significant influence on the activity and stability of methane tri-reforming catalysts; however, the suitability of either strong or weak MSI is subject to catalyst composition.     

Carbon dioxide reforming of methane over nickel catalysts supported on TiO2(001) nanosheets

As we all know, the critical problem of nickel catalysts for carbon dioxide reforming of methane is the deactivation of catalysts due to the carbon deposition and sintering of the active components under high temperature. It was reported that anatase TiO₂ nanosheets with high-energy (001) facets had strong interaction with nickel, which was probably beneficial to resist sintering of nickel nanoparticles and to eliminate deposited carbon via oxygen migration. In this study, Ni nanoparticles were supported on TiO2 nanosheets with exposed high-energy (001) facets. The Ni/TiO₂(001) catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, physisorption of N₂, X-ray photoelectron spectroscopy and H₂ temperature-programmed reduction, and the spent catalysts were characterized by Roman and thermogravimetry analysis. The catalytic performance of Ni/TiO₂(001) catalysts were measured for carbon dioxide reforming of methane reaction. It was found that the prepared Ni/TiO₂(001) catalysts showed reasonably higher catalytic activity and stability compared with the nickel catalyst supported on commercial titanium oxide (P25). The high dispersion of nickel nanoparticles of Ni/TiO₂(001) catalysts was helpful to the resistance towards carbon deposition and the strong metal-support interaction was helpful to the resistance towards nickel sintering on account of the unusual surface properties of TiO₂(001).     

Effect of CaO addition on acid properties of Ni–Ca/Al2O3 catalysts applied to ethanol steam reforming

Ni/Al₂O₃ catalysts containing 5 wt% of Ni and modified by addition of CaO (0–5 wt%) were tested in ethanol steam reforming reaction in order to reduce the dehydration ethanol reaction, which produces ethylene that may polymerize and produce coke. The catalysts were prepared by impregnation (I) and co-precipitation (C) methods. All catalysts were investigated for ethanol steam reforming and the catalytic performance was compared in terms of additive addition. The catalysts 5Ni–5Ca/Al (I) and 5Ni–5Ca/Al (C) were less selective to ethylene production and therefore were characterized by the following techniques: energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), temperature programmed reduction (TPR), X-ray absorption near edge structure (XANES), specific surface area by the BET method, scanning electron microcopy (SEM) and isopropanol decomposition reaction. By comparing the catalysts, the 5Ni–5Ca/Al (I) catalyst presented the lowest acidity and carbon deposition, and also presented no deactivation in 24 h of catalytic test.     

Catalytic performance of silica covered bimetallic nickel-iron encapsulated core-shell microspheres for hydrogen production

Supported nickel-iron catalysts with core/shell structures (Ni,Fe/SiO_2, and Ni/SiO₂, Fe (Imp.)) were synthesized by sol-gel microencapsulation and sol-gel microencapsulation-impregnation methods, respectively. Sol-gel microencapsulation resulted in the formation of Ni and Fe containing alloys, where both Fe and Ni were in the core (Ni,Fe/SiO₂). In the case of combined microencapsulation-impregnation Ni was placed in the center where Fe was on the shell side (Ni/SiO₂, Fe (Imp.)). BET, XRD, SEM, TGA and Raman Spectroscopy techniques were used for catalysts characterization. Catalysts were tested in dry reforming of methane (DRM) reaction which was specially selected to provide a comprehensive utilization of methane and carbon dioxide. The catalytic activity tests were carried out at 750 °C and atmospheric pressure, using stainless steel, temperature-controlled tube reactor. After 3 h of reaction, Ni,Fe/SiO₂ bimetallic core-shell microsphere catalysts with Ni/Fe ratio of 4/1 and 2/1 indicated the highest CH₄ conversions (74% and 68%, respectively) and H₂/CO (0,72 and 0,69) ratios. Ni,Fe/SiO₂ catalysts showed higher activity compared to Ni/SiO₂, Fe (Imp.) catalysts and an activity increase for both types of catalysts were observed due to increasing Ni amount in catalyst structure. Ni,Fe/SiO₂ catalysts were also determined to be highly resistant against coke formation. A significant resistance against coke formation on active sites was achieved via SiC formation during reaction. The catalyst with best performance (4Ni,1Fe/SiO₂) was regenerated after use and tested on following three successive cycles under identical experimental conditions. Results indicated similar activity values with negligible deactivation.     

Hydrogen production by steam reforming of liquefied natural gas (LNG) over ordered mesoporous nickel–alumina catalyst

An ordered mesoporous nickel–alumina catalyst (denoted as OMNA) was prepared by a single-step evaporation-induced self-assembly method, and it was applied to the hydrogen production by steam reforming of liquefied natural gas (LNG). For comparison, a nickel catalyst supported on ordered mesoporous alumina support (denoted as Ni/OMA) was also prepared by an impregnation method. Although both Ni/OMA and OMNA catalysts retained unidimensionally ordered mesoporous structure, textural properties of the catalysts were significantly affected by the preparation method. Nickel species were finely dispersed in the OMNA catalyst as a form of surface nickel aluminate with a high degree of nickel-saturation. On the other hand, both bulk nickel oxide and surface nickel aluminate phases were formed in the network of Ni/OMA catalyst. Nickel species in the OMNA catalyst exhibited not only high reducibility but also strong resistance toward sintering during the reduction process, compared to those in the Ni/OMA catalyst. Both Ni/OMA and OMNA catalysts showed a stable catalytic performance without catalyst deactivation during the steam reforming of LNG due to the confinement effect derived from well-developed ordered mesoporous structure in the catalysts. However, OMNA catalyst with small crystallite size of metallic nickel exhibited higher LNG conversion and hydrogen yield than Ni/OMA catalyst. Furthermore, OMNA catalyst was more active in the steam reforming of LNG than non-ordered mesoporous nickel–alumina catalysts prepared by common surfactant-templating methods using cationic, anionic, and non-ionic surfactants.     

Hydrogen production by aqueous phase reforming of phenol derived from lignin pyrolysis over NiCe/ZSM-5 catalysts

Incipient wetness impregnation was used to synthesized the NiCe/ZSM-5 catalysts with different ratio of Ni:Ce, and CeO₂ was added as an assistant in the synthesis process. The physicochemical properties of the prepared catalysts were characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂-Sorption, H₂ temperature programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared Spectroscopy (FTIR) and ultraviolet–visible diffuse reflectance spectra (UV–Vis DR). The catalytic activities of the obtained catalysts were tested by using the reaction of aqueous phase reforming of phenol to produce hydrogen. Adding appropriate doze of Ce to the catalysts can increase the dispersion of nickel on the ZSM-5 support. The results showed that hydrogen selectivity was higher over 8Ni8Ce/ZSM-5 than using 8Ni/ZSM-5 as aqueous phase reforming catalysts. The content of carbon monoxide in the products after reaction over different catalysts was very low. However, the dispersion of carbon dioxide and hydrocarbons was significantly different over the two catalysts.     

Steam reforming of n-dodecane over mesoporous alumina supported nickel catalysts: Effects of metal-support interaction on nickel catalysts

Developing a highly active and stable Ni-based catalyst is still a challenge for the generation of on-site hydrogen through steam reforming of long-chained hydrocarbons, such as kerosene fuels. Ni nanoparticles (ca. 5 nm) on mesoporous alumina prepared by atomic layer deposition (ALD) were employed in steam reforming of n-dodecane, and exhibited a turnover frequency (TOF) of 477.6 h⁻¹, whereas Ni nanoparticles on commercial alumina support prepared by impregnation method exhibited a TOF of 100 h⁻¹. The high activity of ALD Ni catalysts was ascribed to high reduction degree, as confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and H₂-chemisorption. A deactivation was also observed on the ALD prepared catalysts, which was ascribed to the weak metal-support interaction, as confirmed by H₂ temperature-programmed reduction (TPR). The ALD Ni/Al₂O₃ catalysts were further modified with CeO₂ and they showed enhanced stability with 8% deactivation degree in steam reforming of n-dodecane. Further characterizations of spent catalysts showed that the presence of CeO₂ was favorable for stabilizing Ni nanoparticles by enhancing moderate metal-support interaction, and reducing the formation of coke on the interfaces of NiCeO₂.     

Hydrogen production from oxidative steam reforming of methanol: Effect of the Cu and Ni impregnation on ZrO2 and their molecular simulation studies

Cu and Ni were supported on ZrO₂ by co-impregnation and sequential impregnation methods, and tested in the oxidative steam reforming of methanol (OSRM) reaction for H₂ production as a function of temperature. Surface area of the catalysts showed differences as a function of the order in which the metals were added to zirconia. Among them, the Cu/ZrO₂ catalyst had the lowest surface area. XRD patterns of the bimetallic catalysts did not show diffraction peaks of the Cu, Ni or bimetallic Cu–Ni alloys. In addition, TPR profiles of the bimetallic catalysts had the lowest reduction temperature compared with the monometallic samples. The reactivity of the catalysts in the range of 250–350 °C showed that the bimetallic samples prepared by successive impregnation had highest catalytic activity among all the catalysts studied. These results were also confirmed by theoretical calculations. The reactivity of the monometallic and bimetallic structures obtained by molecular simulation followed the next order: Ni_shellCu_core/ZrO₂ ≅ Cu_shellNi_core/ZrO₂ > Ni/Cu/ZrO₂ > Cu/Ni/ZrO₂ > Cu–Ni/ZrO₂ > Cu/ZrO₂ > Ni/ZrO₂. These findings agree with the experimental results, indicating that the bimetallic catalysts prepared by successive impregnation show a higher reactivity than the Cu–Ni system obtained by co-impregnation. In addition, the selectivity for H₂ production was higher on these catalysts. This result could be associated also to the presence of the bimetallic Cu–Ni and core–shell Ni/Cu nanoparticles on the catalysts, as was evidenced by TEM–EDX analysis, suggesting that the OSRM reaction may be a structure–sensitive reaction.